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Selected Papers from IMETI 2018
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Selected Papers from IMETI 2018

A special issue of Applied Sciences (ISSN 2076-3417).

Deadline for manuscript submissions: closed (31 December 2019) | Viewed by 164026

Special Issue Editors

Prof. Dr. Wen-Hsiang Hsieh

E-Mail Website
Guest Editor
Department of Automation Engineering, National Formosa University, Huwei, Yunlin 632, Taiwan
Interests: innovative applications of mechanisms; mechatronics; automatic machinery
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Jia-Shing Sheu

E-Mail Website
Guest Editor
Department of Computer Science, National Taipei University of Education, Taipei, Taiwan
Interests: signal processing; pattern recognition and image processing; real time face recognition; embedded system
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Minvydas Ragulskis

E-Mail Website
Guest Editor
Department of Mathematical Modelling, Kaunas University of Technology, LT-51368 Kaunas, Lithuania
Interests: development of numerical methods; modelling of optical effects; visual cryptography; nonlinear dynamical systems and chaos
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The 7th International Conference on of Engineering and Technology Innovation (IMETI 2018) will be held in Taoyuan, Taiwan, 2–6 November, 2018. It covers a wide range of fields in science and engineering innovation and aims to bring together engineering technology expertise. The professional from the industry, academia and government to discourse on research and development, professional practice, business and management in the science and engineering fields are welcome to the IMETI2018. IMETI2018 consists of the three sub-conferences and more than 30 regular and special sessions (http://imeti.org/IMETI2018/).

The main goal of this Special Issue, “Selected Papers from IMETII 2018”, is to present the latest advances in research and novel applications of Engineering and Technology, especially on Materials Science, Industry 4.0 and Automation Engineering, Intelligent Computing and System, Computer and Information Engineering, and Green Technology and New Energy. Potential topics include, but are not limited to:

  • Materials Science
  • Mechatronic and Robotics Engineering
  • Electrical and Electronic Engineering
  • Optical Engineering
  • Chemical and Biomedical Engineering
  • Computer and Information Engineering
  • Green Technology, New Energy, and Civil Engineering
  • Industry 4.0 and Automation Engineering
  • Control Engineering
  • Mechanical Engineering
  • Nanotechnology
  • Environmental, Food, Health Science and Technology
  • Intelligent Computing and System

Prof. Dr. Wen-Hsiang Hsieh
Prof. Dr. Jia-Shing Sheu
Prof. Dr. Minvydas Ragulskis
Guest Editors

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • IMETI, ICETI, ICBEI, ICECEI
  • Innovation
  • Materials Science
  • Industry 4.0
  • Intelligent Computing and System
  • Green Technology
  • New Energy

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Published Papers (38 papers)

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Research

14 pages, 6461 KiB  
Article
Laser Welding on Cerclage Wire Joining in Femur Surgery
by Nutchanat Thongchuea, Eakkachai Warinsiriruk and Yin-Tien Wang
Appl. Sci. 2020, 10(7), 2407; https://doi.org/10.3390/app10072407 - 1 Apr 2020
Cited by 1 | Viewed by 3837
Abstract
Stainless steel wires with fiber-laser welding on lap joints are first proposed in this study to be used as cerclage wire joints for modern femur surgery, because of their potentially larger joint strength and less loosening failure than traditional joint devices. In this [...] Read more.
Stainless steel wires with fiber-laser welding on lap joints are first proposed in this study to be used as cerclage wire joints for modern femur surgery, because of their potentially larger joint strength and less loosening failure than traditional joint devices. In this feasibility study, an experiment was set up to determine adequate parameters for the laser welding process in order to ensure that the wire joint of cerclage has good weld appearance, free oxidation, and suitable joint strength. A stainless steel wire 316L with a diameter of 1.6 mm, flare-welded on lap joint was used in the experiment as a specimen cerclage wire joint. Two major effective parameters were chosen for controlling a suitable fusion weld, including charge voltage and multiple frequencies of the laser irradiation. The adequate area of the laser parameters was determined from the experiment, including the ranges of charge voltage, multiple frequencies, and pulse width. The suitable welded lengths of specimens were also studied in the mechanical test to validate the joint strength. Suggested welded length has a better tensile strength than traditional cerclage joints. The paper concludes that the stainless wire joints with a fiber laser weld represents a promising alternative to traditional cerclage joint devices for modern femur surgery. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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11 pages, 3273 KiB  
Article
Wireless Epidermal Six-Axis Inertial Measurement Units for Real-Time Joint Angle Estimation
by Jae Keun Lee, Seung Ju Han, Kangil Kim, Yoon Hyuk Kim and Sangmin Lee
Appl. Sci. 2020, 10(7), 2240; https://doi.org/10.3390/app10072240 - 26 Mar 2020
Cited by 9 | Viewed by 3374
Abstract
Technological advances in wireless communications, miniaturized sensors, and low-power electronics have made it possible to implement integrated wireless body area networks (WBANs). These developments enable the applications of wireless wearable systems for diagnosis, health monitoring, rehabilitation, and dependency care. Across the current range [...] Read more.
Technological advances in wireless communications, miniaturized sensors, and low-power electronics have made it possible to implement integrated wireless body area networks (WBANs). These developments enable the applications of wireless wearable systems for diagnosis, health monitoring, rehabilitation, and dependency care. Across the current range of commercial wearable devices, the products are not firmly fixed to the human body. To minimize data error caused by movement of the human body and to achieve accurate measurements, it is essential to bring the wearable device close to the skin. This paper presents the implementation of a patch-type, six-axis inertial measurement unit (IMU) with wireless communication technology. The device comprises hard-electronic components on a stretchable elastic substrate for application in epidermal electronics, to collect precise data from the human body. Instead of the commonly used cleanroom processes of implementing devices on a stretchable substrate, a simple and inexpensive “cut-solder-paste” method is adopted to fabricate complex, convoluted interconnections. Thus, the signal distortions in the proposed device can be minimized during various physical activities and skin deformations when used in gait analysis. The inertial sensor data measured from the motion of the body can be sent in real-time via Bluetooth to any processing unit enabled with such a widespread standard wireless interface. For performance evaluation, the implemented device is mounted on a rotation plate in order to compare performance with the conventional product. In addition, an experiment on joint angle estimation is performed by attaching the device to an actual human body. The preliminary results of the device indicate the potential to monitor people in remote settings for applications in mobile health, human-computer interfaces (HCIs), and wearable robots. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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16 pages, 4576 KiB  
Article
Damping and Natural Period Evaluation of Tall RC Buildings Using Full-Scale Data in Korea
by Taehyu Ha, Seung-Hoon Shin and Hongjin Kim
Appl. Sci. 2020, 10(5), 1568; https://doi.org/10.3390/app10051568 - 25 Feb 2020
Cited by 13 | Viewed by 5129
Abstract
In recent years, the main usage of reinforced concrete (RC) structures in Korea has shifted from low-rise residential and commercial buildings to high-rise buildings. Because an increasing number of high-rise RC buildings are being built, especially in coastal cities, which are periodically hit [...] Read more.
In recent years, the main usage of reinforced concrete (RC) structures in Korea has shifted from low-rise residential and commercial buildings to high-rise buildings. Because an increasing number of high-rise RC buildings are being built, especially in coastal cities, which are periodically hit by typhoons, wind-induced motion and the corresponding serviceability issues have attracted considerable attention. Natural period and damping ratio are the most important factors for estimating the design wind load and wind-induced response in the design of tall buildings. However, the Korean Building Code (KBC 2009) does not specify empirical formulae for estimating the natural period and damping ratio for wind design, unlike seismic design. In this study, the damping ratio and natural period of existing concrete buildings in Korea are measured and compared to those obtained using the formulae provided in various codes and research works. Furthermore, design formulae for estimating natural frequency and damping ratio for wind design are proposed based on the measured data. For this purpose, ambient vibration measurement is performed for 58 RC buildings with heights of 24.2–305 m. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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16 pages, 3699 KiB  
Article
Detecting Mixed-Type Intrusion in High Adaptability Using Artificial Immune System and Parallelized Automata
by Fu-I Chou, Wen-Hsien Ho, Yenming J. Chen, Jinn-Tsong Tsai and Chia-Wen Chang
Appl. Sci. 2020, 10(5), 1566; https://doi.org/10.3390/app10051566 - 25 Feb 2020
Cited by 3 | Viewed by 2208
Abstract
This study applies artificial immune system and parallelized finite-state machines to construct an intrusion detection algorithm for spotting hidden threats in massive number of packets. Existing intrusion detections are mostly not focused on adaptability for mixed and changing attacks, which results in low [...] Read more.
This study applies artificial immune system and parallelized finite-state machines to construct an intrusion detection algorithm for spotting hidden threats in massive number of packets. Existing intrusion detections are mostly not focused on adaptability for mixed and changing attacks, which results in low detection rate in new and mixed-type attacks. Using the characteristics of artificial immune and state transition can address the attacks in evolutionary patterns and track the anomalies in nonconsecutive packets. The proposed immune algorithm in this study is highly efficient based on a selection step in multi-island migration. Result shows that the algorithm can effectively detect mixed-type attacks and obtains an overall accuracy of 95.9% in testing data. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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14 pages, 5607 KiB  
Article
Time-Varying Dynamic Analysis of a Helical-Geared Rotor-Bearing System with Three-Dimensional Motion Due to Shaft Deformation
by Ying-Chung Chen
Appl. Sci. 2020, 10(4), 1542; https://doi.org/10.3390/app10041542 - 24 Feb 2020
Cited by 6 | Viewed by 3552
Abstract
The rotordynamics of a helical-geared rotor-bearing system were investigated. A new dynamic model for a helical-geared rotor-bearing system, which takes into account three-dimensional (3-D) motion due to rotating shaft deformation, was proposed. The proposed model considers the time-varying effect, which in other models, [...] Read more.
The rotordynamics of a helical-geared rotor-bearing system were investigated. A new dynamic model for a helical-geared rotor-bearing system, which takes into account three-dimensional (3-D) motion due to rotating shaft deformation, was proposed. The proposed model considers the time-varying effect, which in other models, is considered constant. The system equations of motion were obtained by applying Lagrange’s equation, and the dynamic responses were computed by the fourth-order Runge–Kutta method. The time-varying dynamic responses of the helix angle, transverse pressure angle, gear pair center distance, and total contact ratio were investigated. The numerical results show that the time-varying effect is an important factor in gear vibration analysis and cannot be neglected when the helical geared rotor-bearing system has a lower stiffness. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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11 pages, 4522 KiB  
Article
Accuracy Evaluation of Geoid Heights in the National Control Points of South Korea Using High-Degree Geopotential Model
by Kwang Bae Kim, Hong Sik Yun and Ha Jung Choi
Appl. Sci. 2020, 10(4), 1466; https://doi.org/10.3390/app10041466 - 21 Feb 2020
Cited by 13 | Viewed by 3837
Abstract
Precise geoid heights are not as important for understanding Earth’s gravity field, but they are important to geodesy itself, since the vertical datum is defined as geoid in a cm-level accuracy. Several high-degree geopotential models have been derived lately by using satellite tracking [...] Read more.
Precise geoid heights are not as important for understanding Earth’s gravity field, but they are important to geodesy itself, since the vertical datum is defined as geoid in a cm-level accuracy. Several high-degree geopotential models have been derived lately by using satellite tracking data such as those from Gravity Recovery and Climate Experiment (GRACE) and Gravity Field and Steady-State Ocean Circulation Explorer (GOCE), satellite altimeter data, and terrestrial and airborne gravity data. The Korean national geoid (KNGeoid) models of the National Geographic Information Institute (NGII) were developed using the latest global geopotential models (GGMs), which are combinations of gravity data from satellites and land gravity data. In this study, geoid heights calculated from the latest high-degree GGMs were used to evaluate the accuracy of the three GGMs (European Improved Gravity model of Earth by New techniques (EIGEN)-6C4, Earth Gravitational Model 2008 (EGM2008), and GOCE-EGM2008 combined model (GECO)) by comparing them with the geoid heights derived from the Global Navigation Satellite System (GNSS)/leveling of the 1182 unified control points (UCPs) that have been installed by NGII in South Korea since 2008. In addition, the geoid heights derived from the KNGeoid models were compared with the geoid heights derived from the GNSS/leveling of the 1182 UCPs to assess the accuracy of the KNGeoid models in terms of relative geoid heights for further gravimetric geoid determination studies in South Korea. As a result, the EGM2008 model could be selected as the suitable GGM from among the three GGMs for determining a gravimetric geoid model for South Korea. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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18 pages, 2497 KiB  
Article
Inheritance Coding with Gagné-Based Learning Hierarchy Approach to Developing Mathematics Skills Assessment Systems
by Wei-Ling Tang, Jinn-Tsong Tsai and Ching-Ying Huang
Appl. Sci. 2020, 10(4), 1465; https://doi.org/10.3390/app10041465 - 21 Feb 2020
Cited by 7 | Viewed by 4750
Abstract
This study developed an inheritance coding with Gagné-based learning hierarchy approach to building systems for assessing mathematics skills and diagnosing student learning problems. The proposed Gagné-based learning hierarchy approach combines Gagné learning hierarchy theory with an inheritance coding approach. First, Gagné learning hierarchy [...] Read more.
This study developed an inheritance coding with Gagné-based learning hierarchy approach to building systems for assessing mathematics skills and diagnosing student learning problems. The proposed Gagné-based learning hierarchy approach combines Gagné learning hierarchy theory with an inheritance coding approach. First, Gagné learning hierarchy theory is used to generate test questions and learning path diagrams for a skills assessment system. To assess learning achievement, an inheritance coding approach is used to encode the test questions according to learning hierarchy paths. The analysis, design, development, implementation, and evaluation design model is used throughout the process of developing the assessment system. Statistical analyses of the test questions for assessing student learning achievement included expert validity, internal reliability, test–retest reliability, and parallel-form reliability. System performance questionnaires were also designed to survey the opinions of the students regarding the mathematics skills assessment system. The internal reliability of the overall questionnaire was also calculated. The experimental practical application of the assessment system, developed by the Gagné-based learning hierarchy approach, showed that it can accurately diagnose student learning barriers and provide learning suggestions for students and teachers. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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16 pages, 2427 KiB  
Article
Diversity Balancing for Two-Stage Collaborative Filtering in Recommender Systems
by Liang Zhang, Quanshen Wei, Lei Zhang, Baojiao Wang and Wen-Hsien Ho
Appl. Sci. 2020, 10(4), 1257; https://doi.org/10.3390/app10041257 - 13 Feb 2020
Cited by 19 | Viewed by 4169
Abstract
Conventional recommender systems are designed to achieve high prediction accuracy by recommending items expected to be the most relevant and interesting to users. Therefore, they tend to recommend only the most popular items. Studies agree that diversity of recommendations is as important as [...] Read more.
Conventional recommender systems are designed to achieve high prediction accuracy by recommending items expected to be the most relevant and interesting to users. Therefore, they tend to recommend only the most popular items. Studies agree that diversity of recommendations is as important as accuracy because it improves the customer experience by reducing monotony. However, increasing diversity reduces accuracy. Thus, a recommendation algorithm is needed to recommend less popular items while maintaining acceptable accuracy. This work proposes a two-stage collaborative filtering optimization mechanism that obtains a complete and diversified item list. The first stage of the model incorporates multiple interests to optimize neighbor selection. In addition to using conventional collaborative filtering to predict ratings by exploiting available ratings, the proposed model further considers the social relationships of the user. A novel ranking strategy is then used to rearrange the list of top-N items while maintaining accuracy by (1) rearranging the area controlled by the threshold and by (2) maximizing popularity while maintaining an acceptable reduction in accuracy. An extensive experimental evaluation performed in a real-world dataset confirmed that, for a given loss of accuracy, the proposed model achieves higher diversity compared to conventional approaches. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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17 pages, 3268 KiB  
Article
A Robust Levitation Control of Maglev Vehicles Subject to Time Delay and Disturbances: Design and Hardware Experimentation
by You-gang Sun, Si Xie, Jun-qi Xu and Guo-bin Lin
Appl. Sci. 2020, 10(3), 1179; https://doi.org/10.3390/app10031179 - 10 Feb 2020
Cited by 16 | Viewed by 4110
Abstract
Maglev vehicles have become a new type of transportation system with higher speed, lower noise, and commercial appeal. Magnetic-suspension systems, which have high nonlinearity and open-loop instability, are the core components of maglev vehicles. The high-performance control of maglev vehicles has been the [...] Read more.
Maglev vehicles have become a new type of transportation system with higher speed, lower noise, and commercial appeal. Magnetic-suspension systems, which have high nonlinearity and open-loop instability, are the core components of maglev vehicles. The high-performance control of maglev vehicles has been the focus of numerous studies. Encountering challenges in the levitation control of maglev vehicles in the form of uncertain time delays and disturbances is unavoidable. To cope with these problems, this study presents the design of an adaptive robust controller based on the Riccati method and sliding-mode technology, simultaneously taking into account the influence of time delays and disturbances. The asymptotic stability of the closed-loop system with the proposed control law is proved by the Lyapunov method. Control performances of the proposed controller are shown in the simulation results. Together with the consistently stabilizing outputs, the presented control approach can handle time delays and disturbances well. Finally, experiments were also implemented to examine its practical control performance of the robust levitation-control law. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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10 pages, 5587 KiB  
Article
A Novel Top-Down Fabrication Process for Vertically-Stacked Silicon-Nanowire Array
by Kangil Kim, Jae Keun Lee, Seung Ju Han and Sangmin Lee
Appl. Sci. 2020, 10(3), 1146; https://doi.org/10.3390/app10031146 - 8 Feb 2020
Cited by 17 | Viewed by 4310
Abstract
Silicon nanowires are widely used for sensing applications due to their outstanding mechanical, electrical, and optical properties. However, one of the major challenges involves introducing silicon-nanowire arrays to a specific layout location with reproducible and controllable dimensions. Indeed, for integration with microscale structures [...] Read more.
Silicon nanowires are widely used for sensing applications due to their outstanding mechanical, electrical, and optical properties. However, one of the major challenges involves introducing silicon-nanowire arrays to a specific layout location with reproducible and controllable dimensions. Indeed, for integration with microscale structures and circuits, a monolithic wafer-level process based on a top-down silicon-nanowire array fabrication method is essential. For sensors in various electromechanical and photoelectric applications, the need for silicon nanowires (as a functional building block) is increasing, and thus monolithic integration is highly required. In this paper, a novel top-down method for fabricating vertically-stacked silicon-nanowire arrays is presented. This method enables the fabrication of lateral silicon-nanowire arrays in a vertical direction, as well as the fabrication of an increased number of silicon nanowires on a finite dimension. The proposed fabrication method uses a number of processes: photolithography, deep reactive-ion etching, and wet oxidation. In applying the proposed method, a vertically-aligned silicon-nanowire array, in which a single layer consists of three vertical layers with 20 silicon nanowires, is fabricated and analyzed. The diamond-shaped cross-sectional dimension of a single silicon nanowire is approximately 300 nm in width and 20 μm in length. The developed method is expected to result in highly-sensitive, reproducible, and low-cost silicon-nanowire sensors for various biomedical applications. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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22 pages, 10727 KiB  
Article
Video-Based Parking Occupancy Detection for Smart Control System
by Lun-Chi Chen, Ruey-Kai Sheu, Wen-Yi Peng, Jyh-Horng Wu and Chien-Hao Tseng
Appl. Sci. 2020, 10(3), 1079; https://doi.org/10.3390/app10031079 - 6 Feb 2020
Cited by 34 | Viewed by 9427
Abstract
Street lighting is a fundamental aspect of security systems in homes, industrial facilities, and public places. To detect parking lot occupancy in outdoor environments, street light control plays a crucial role in smart surveillance applications that can perform robustly in extreme surveillance environments. [...] Read more.
Street lighting is a fundamental aspect of security systems in homes, industrial facilities, and public places. To detect parking lot occupancy in outdoor environments, street light control plays a crucial role in smart surveillance applications that can perform robustly in extreme surveillance environments. However, traditional parking occupancy systems are mostly implemented for outdoor environments using costly sensor-based techniques. This study uses the Jetson TX2 to develop a method that can accurately identify street parking occupancy and control streetlights to assist occupancy detection, thereby reducing costs, and can adapt to various weather conditions. The proposed method adopts You Only Look Once version 3 (YOLO v3, Seattle, WA, USA) based on MobileNet version 2 (MobileNet v2, Salt Lake City, UT, USA), which is area-based and uses voting to stably recognize occupancy status. This solution was verified using the CNRPark + EXT dataset, a simulated model, and real scenes photographed with a camera. Our experiments revealed that the proposed framework can achieve stable parking occupancy detection in streets. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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11 pages, 2702 KiB  
Article
Planetary-Gearbox Fault Classification by Convolutional Neural Network and Recurrence Plot
by Dan-Feng Wang, Yu Guo, Xing Wu, Jing Na and Grzegorz Litak
Appl. Sci. 2020, 10(3), 932; https://doi.org/10.3390/app10030932 - 31 Jan 2020
Cited by 32 | Viewed by 4083
Abstract
Recurrence-plot (RP) analysis is a graphical tool to visualize and analyze the recurrence of nonlinear dynamic systems. By combining the advantages of the RP and a convolutional neural network (CNN), a fault-classification scheme for planetary gear sets is proposed in this paper. In [...] Read more.
Recurrence-plot (RP) analysis is a graphical tool to visualize and analyze the recurrence of nonlinear dynamic systems. By combining the advantages of the RP and a convolutional neural network (CNN), a fault-classification scheme for planetary gear sets is proposed in this paper. In the proposed approach, a vibration is first picked up from the planetary-gear test rig and converted into an angular-domain quasistationary signal through computed order tracking to eliminate the frequency blur caused by speed fluctuations. Then, the signal in the angular domain is divided into several segments, and each segment is processed by the RP to constitute the training sample. Moreover, a two-dimensional CNN model was developed to adaptively extract faulty features. Experiments on a planetary-gear test rig with four conditions under three operating speeds were carried out. The results of measured vibration demonstrated the validity of CNN and recurrence plot analysis for the fault classification of planetary-gear sets. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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11 pages, 3662 KiB  
Article
Vessel Trajectory Reconstruction Based on Functional Data Analysis Using Automatic Identification System Data
by Myeong-Hun Jeong, Seung-Bae Jeon, Tae-Young Lee, Min Kyo Youm and Dong-Ha Lee
Appl. Sci. 2020, 10(3), 881; https://doi.org/10.3390/app10030881 - 28 Jan 2020
Cited by 5 | Viewed by 2866
Abstract
This study provides an automatic shipping-route construction method using functional data analysis (FDA), which analyzes information about curves, such as multiple data points over time. The proposed approach includes two steps: outlier detection and shipping-route construction. This study uses automatic-identification system (AIS) data [...] Read more.
This study provides an automatic shipping-route construction method using functional data analysis (FDA), which analyzes information about curves, such as multiple data points over time. The proposed approach includes two steps: outlier detection and shipping-route construction. This study uses automatic-identification system (AIS) data for the experiments. The effectiveness of the proposed method is demonstrated through case studies, wherein our approach is compared with the Mahalanobis distance method for trajectory-outlier detection, and the performance of vessel trajectory reconstruction is compared with that of a density-based approach. The proposed method improves understanding of vessel-movement dynamics, thereby improving maritime monitoring and security. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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10 pages, 6336 KiB  
Article
Evaluation of Long-Term Performance for Bonded Natural Stone Pavement Using Accelerated Pavement Test [Part Ⅱ: Skid Resistance, Response of Deflection and FEM Analysis]
by Junho Gong, Eui-Seok Han, Sun-Kyu Park and Dooyong Cho
Appl. Sci. 2020, 10(3), 879; https://doi.org/10.3390/app10030879 - 28 Jan 2020
Cited by 4 | Viewed by 2785
Abstract
Natural stone-paved roads have been generally used to preserve historical regions due to its architectural aesthetic aspect and environmental impact. However, there are limitations of travelling speed and traffic volume owing to the defects caused by the increased traffic loading and volume. To [...] Read more.
Natural stone-paved roads have been generally used to preserve historical regions due to its architectural aesthetic aspect and environmental impact. However, there are limitations of travelling speed and traffic volume owing to the defects caused by the increased traffic loading and volume. To deal with these hindrances, ultra-rapid-hardening cement for both jointing and laying course materials in rigid small element pavement was considered. The objective of the present study was to continuously evaluate and compare the long-term performance of the suggested bound stone pavement throughout the various test criteria such as skid resistance and Falling Weight Deflectometer tests. The skid resistance outcome was met to the requirement and the response of deflection was measured following by related test method. To compare rut depth, the Finite Element Method (FEM) analysis was performed by modelling with material properties and by creating the loading cycle for imitating the Accelerated Pavement Testing (APT). The maximum deflections of asphalt, concrete block, stone A and stone B were calculated to 17.7, 6.1, 6.3, and 3.6 mm, respectively. Compared to the final outcomes of APT and FEM analysis, there was a difference ranging from 2.1 to 2.3 mm in bound stone pavement B and A, respectively. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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14 pages, 3787 KiB  
Article
Effect of Mechanical Stimulation Applied to the Lower-Limb Musculature on Stability and Function of Stair Climbing
by Seunghun Ko, Kiyoung Kwak, Huigyun Kim and Dongwook Kim
Appl. Sci. 2020, 10(3), 799; https://doi.org/10.3390/app10030799 - 23 Jan 2020
Cited by 2 | Viewed by 2911
Abstract
Mechanical muscle-tendon vibration affects musculature and the nervous system. As the vibrations used in previous studies were varied, consistently determining the effect of mechanical vibration was challenging. Additionally, only a few studies have applied vibrations to dynamic motion. This study investigated whether the [...] Read more.
Mechanical muscle-tendon vibration affects musculature and the nervous system. As the vibrations used in previous studies were varied, consistently determining the effect of mechanical vibration was challenging. Additionally, only a few studies have applied vibrations to dynamic motion. This study investigated whether the vibration based on the sensorimotor response could affect the stability and function of stair climbing. Electroencephalogram (EEG) signals were recorded from the sensorimotor area, and mu rhythms, dependent on the vibration frequencies, were analyzed. Based on the analysis, the vibratory stimulus conditions were set and applied to the Achilles tendon of the lower limb during stair climbing. Simultaneously, electromyogram (EMG) signals from the gastrocnemius lateralis (GL), gastrocnemius medialis (GM), soleus (SOL), and tibialis anterior (TA) were recorded. Activations and co-activations of the shank muscles were analyzed according to the phases of stair climbing. When vibration was applied, the TA activation decreased in the pull-up (PU) phase, and calf muscle activations increased during the forward continuous (FCN) phase. These changes and their degrees differ significantly between stimulus conditions (p < 0.05). Co-activation changes, which differed significantly with conditions (p < 0.05), appeared mostly in the PU. These results imply that the vibration affects stability and function of stair climbing, suggesting that the vibration characteristics should be considered when they are applied to dynamic movement. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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10 pages, 4015 KiB  
Article
Development of a Structural Monitoring System for Cable Bridges by Using Seismic Accelerometers
by Seong-Hoon Jeong, Won-Seok Jang, Jin-Won Nam, Hohyun An and Dae-Jin Kim
Appl. Sci. 2020, 10(2), 716; https://doi.org/10.3390/app10020716 - 20 Jan 2020
Cited by 6 | Viewed by 3266
Abstract
In this study, a structural health monitoring system for cable-stayed bridges is developed. In the system, condition assessment of the structure is performed based on measured records from seismic accelerometers. Response indices are defined to monitor structural safety and serviceability and derived from [...] Read more.
In this study, a structural health monitoring system for cable-stayed bridges is developed. In the system, condition assessment of the structure is performed based on measured records from seismic accelerometers. Response indices are defined to monitor structural safety and serviceability and derived from the measured acceleration data. The derivation process of the indices is structured to follow the transformation from the raw data to the final outcome. The process includes, noise filtering, baseline correction, numerical integration, and calculation of relative differences. The system is packed as a condition assessment program, which consists of four major process of the structural health evaluation: (i) format conversion of the raw data, (ii) noise filtering, (iii) generation of response indices, and (iv) condition evaluation. An example set of limit states is presented to evaluate the structural condition of the test-bed cable-stayed bridge. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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19 pages, 4787 KiB  
Article
Evaluation of Condition of Concrete Structures Using Ultrasonic Pulse Velocity Method
by Seonguk Hong, Sangki Yoon, Jonghyun Kim, Changjong Lee, Seunghun Kim and Yongtaeg Lee
Appl. Sci. 2020, 10(2), 706; https://doi.org/10.3390/app10020706 - 19 Jan 2020
Cited by 48 | Viewed by 5726
Abstract
The purpose of this study is to estimate the compressive strength according to the age of the concrete structure using ultrasonic pulse velocity method. If the correlation between the ultrasonic pulse velocity and the compressive strength according to the age is derived, the [...] Read more.
The purpose of this study is to estimate the compressive strength according to the age of the concrete structure using ultrasonic pulse velocity method. If the correlation between the ultrasonic pulse velocity and the compressive strength according to the age is derived, the compressive strength of the early age of the concrete structure can be estimated at the new construction site and the compressive strength of the existing structure can be estimated at the remodeling construction site. Concrete structural specimens were constructed with 123 specimens by setting 9 parameters based on the design compressive strength of 24, 30, 40 MPa at 16, 20, 24, 48, 72, 120, 168, 360, 672 h. For the calculation of the average ultrasonic velocity according to the age of concrete, it is carried out according to KS F 2731, ASTM C597 and ACI 228-2R, and the concrete compressive strength is carried out according to KS F 2405. From correlation between ultrasonic pulse velocity and compressive strength, this experiment suggests compressive strength estimation equation. The proposed estimation equation confirmed that it is possible to estimate the compressive strength of concrete according to its age using nondestructive test methods. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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21 pages, 9485 KiB  
Article
Modeling Tide–Induced Groundwater Response in a Coastal Confined Aquifer Using the Spacetime Collocation Approach
by Cheng-Yu Ku, Chih-Yu Liu, Yan Su, Luxi Yang and Wei-Po Huang
Appl. Sci. 2020, 10(2), 439; https://doi.org/10.3390/app10020439 - 7 Jan 2020
Cited by 5 | Viewed by 2875
Abstract
This paper presents the modeling of tide–induced groundwater response using the spacetime collocation approach (SCA). The newly developed SCA begins with the consideration of Trefftz basis functions which are general solutions of the governing equation deriving from the separation of variables. The solution [...] Read more.
This paper presents the modeling of tide–induced groundwater response using the spacetime collocation approach (SCA). The newly developed SCA begins with the consideration of Trefftz basis functions which are general solutions of the governing equation deriving from the separation of variables. The solution of the groundwater response in a coastal confined aquifer with an estuary boundary where the phase and amplitude of tide can vary with time and position is then approximated by the linear combination of Trefftz basis functions using the superposition theorem. The SCA is validated for several numerical examples with analytical solutions. The comparison of the results and accuracy for the SCA with the time–marching finite difference method is carried out. In addition, the SCA is adopted to examine the tidal and groundwater piezometer data at the Xing–Da port, Kaohsiung, Taiwan. The results demonstrate the SCA may obtain highly accurate results. Moreover, it shows the advantages of the SCA such that we only discretize by a set of points on the spacetime boundary without tedious mesh generation and thus significantly enhance the applicability. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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12 pages, 4062 KiB  
Article
A 24.88 nV/√Hz Wheatstone Bridge Readout Integrated Circuit with Chopper-Stabilized Multipath Operational Amplifier
by Kwonsang Han, Hyungseup Kim, Jaesung Kim, Donggeun You, Hyunwoo Heo, Yongsu Kwon, Junghoon Lee and Hyoungho Ko
Appl. Sci. 2020, 10(1), 399; https://doi.org/10.3390/app10010399 - 5 Jan 2020
Cited by 9 | Viewed by 7801
Abstract
This paper proposes a low noise readout integrated circuit (IC) with a chopper-stabilized multipath operational amplifier suitable for a Wheatstone bridge sensor. The input voltage of the readout IC changes due to a change in input resistance, and is efficiently amplified using a [...] Read more.
This paper proposes a low noise readout integrated circuit (IC) with a chopper-stabilized multipath operational amplifier suitable for a Wheatstone bridge sensor. The input voltage of the readout IC changes due to a change in input resistance, and is efficiently amplified using a three-operational amplifier instrumentation amplifier (IA) structure with high input impedance and adjustable gain. Furthermore, a chopper-stabilized multipath structure is applied to the operational amplifier, and a ripple reduction loop (RRL) in the low frequency path (LFP) is employed to attenuate the ripple generated by the chopper stabilization technique. A 12-bit successive approximation register (SAR) analog-to-digital converter (ADC) is employed to convert the output voltage of the three-operational amplifier IA into digital code. The Wheatstone bridge readout IC is manufactured using a standard 0.18 µm complementary metal-oxide-semiconductor (CMOS) technology, drawing 833 µA current from a 1.8 V supply. The input range and the input referred noise are ±20 mV and 24.88 nV/√Hz, respectively. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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15 pages, 9187 KiB  
Article
Low-Noise Multimodal Reconfigurable Sensor Readout Circuit for Voltage/Current/Resistive/Capacitive Microsensors
by Donggeun You, Hyungseup Kim, Jaesung Kim, Kwonsang Han, Hyunwoo Heo, Yongsu Kwon, Gyungtae Kim, Woo Suk Sul, Jong Won Lee, Boung Ju Lee and Hyoungho Ko
Appl. Sci. 2020, 10(1), 348; https://doi.org/10.3390/app10010348 - 2 Jan 2020
Cited by 6 | Viewed by 4640
Abstract
This paper presents a low-noise reconfigurable sensor readout circuit with a multimodal sensing chain for voltage/current/resistive/capacitive microsensors such that it can interface with a voltage, current, resistive, or capacitive microsensor, and can be reconfigured for a specific sensor application. The multimodal sensor readout [...] Read more.
This paper presents a low-noise reconfigurable sensor readout circuit with a multimodal sensing chain for voltage/current/resistive/capacitive microsensors such that it can interface with a voltage, current, resistive, or capacitive microsensor, and can be reconfigured for a specific sensor application. The multimodal sensor readout circuit consists of a reconfigurable amplifier, programmable gain amplifier (PGA), low-pass filter (LPF), and analog-to-digital converter (ADC). A chopper stabilization technique was implemented in a multi-path operational amplifier to mitigate 1/f noise and offsets. The 1/f noise and offsets were up-converted by a chopper circuit and caused an output ripple. An AC-coupled ripple rejection loop (RRL) was implemented to reduce the output ripple caused by the chopper. When the amplifier was operated in the discrete-time mode, for example, the capacitive-sensing mode, a correlated double sampling (CDS) scheme reduced the low-frequency noise. The readout circuit was designed to use the 0.18-µm complementary metal-oxide-semiconductor (CMOS) process with an active area of 9.61 mm2. The total power consumption was 2.552 mW with a 1.8-V supply voltage. The measured input referred noise in the voltage-sensing mode was 5.25 µVrms from 1 Hz to 200 Hz. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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20 pages, 2968 KiB  
Article
Risk Quantification and Analysis of Coupled Factors Based on the DEMATEL Model and a Bayesian Network
by Jian Jiao, Mengwei Wei, Yuan Yuan and Tingdi Zhao
Appl. Sci. 2020, 10(1), 317; https://doi.org/10.3390/app10010317 - 31 Dec 2019
Cited by 22 | Viewed by 3666
Abstract
With the developing of high integrations in large scale systems, such as aircraft and other industrial systems, there are new challenges in safety analysis due to the complexity of the mission process and the more complicated coupling characteristic of multi-factors. Aiming at the [...] Read more.
With the developing of high integrations in large scale systems, such as aircraft and other industrial systems, there are new challenges in safety analysis due to the complexity of the mission process and the more complicated coupling characteristic of multi-factors. Aiming at the evaluation of coupled factors as well as the risk of the mission, this paper proposes a combined technology based on the Decision Making Trial and Evaluation Laboratory (DEMATEL) model and the Bayesian network (BN). After identifying and classifying the risk factors from the perspectives of humans, machines, the environment, and management, the DEMATEL technique is adopted to assess their direct and/or indirect coupling relationships to determine the importance and causality of each factor; moreover, the relationship matrix in the DEMATEL model is used to generate the BN model, including its parameterization. The inverse reasoning theory is then implemented to derive the probability, and the risk of the coupled factors is evaluated by an assessment model integrating the probability and severity. Furthermore, the key risk factors are identified based on the risk radar diagram and the Pareto rule to support the preventive measurements. Finally, an application of the take-off process of aircraft is provided to demonstrate the proposed method. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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12 pages, 5865 KiB  
Article
Low-Noise Chopper-Stabilized Multi-Path Operational Amplifier with Nested Miller Compensation for High-Precision Sensors
by Jaesung Kim, Hyungseup Kim, Kwonsang Han, Donggeun You, Hyunwoo Heo, Yongsu Kwon, Dong-il “Dan” Cho and Hyoungho Ko
Appl. Sci. 2020, 10(1), 281; https://doi.org/10.3390/app10010281 - 30 Dec 2019
Cited by 7 | Viewed by 6869
Abstract
This paper presents a low-noise multi-path operational amplifier for high-precision sensors. A chopper stabilization technique is applied to the amplifier to remove offset and flicker noise. A ripple reduction loop (RRL) is designed to remove the ripple generated in the process of up-modulating [...] Read more.
This paper presents a low-noise multi-path operational amplifier for high-precision sensors. A chopper stabilization technique is applied to the amplifier to remove offset and flicker noise. A ripple reduction loop (RRL) is designed to remove the ripple generated in the process of up-modulating the flicker noise and offset. To cancel the notch in the overall transfer function due to the RRL operation, a multi-path architecture using both a low-frequency path (LFP) and high-frequency path (HFP) is implemented. The low frequency path amplifier is implemented using the chopper technique and the RRL. In the high-frequency path amplifier, a class-AB output stage is implemented to improve the power efficiency. The transfer functions of the LFP and HFP induce a first-order frequency response in the system through nested Miller compensation. The low-noise multi-path amplifier was fabricated using a 0.18 µm 1P6M complementary metal-oxide-semiconductor (CMOS) process. The power consumption of the proposed low-noise operational amplifier is 0.174 mW with a 1.8 V supply and an active area of 1.18 mm2. The proposed low-noise amplifier has a unit gain bandwidth (UGBW) of 3.16 MHz, an input referred noise of 11.8 nV/√Hz, and a noise efficiency factor (NEF) of 4.46. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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9 pages, 3894 KiB  
Article
Fully Differential Chopper-Stabilized Multipath Current-Feedback Instrumentation Amplifier with R-2R DAC Offset Adjustment for Resistive Bridge Sensors
by Yongsu Kwon, Hyungseup Kim, Jaesung Kim, Kwonsang Han, Donggeun You, Hyunwoo Heo, Dong-il “Dan” Cho and Hyoungho Ko
Appl. Sci. 2020, 10(1), 63; https://doi.org/10.3390/app10010063 - 20 Dec 2019
Cited by 18 | Viewed by 5157
Abstract
A fully differential multipath current-feedback instrumentation amplifier (CFIA) for a resistive bridge sensor readout integrated circuit (IC) is proposed. To reduce the CFIA’s own offset and 1/f noise, a chopper stabilization technique is implemented. To attenuate the output ripple caused by chopper up-modulation, [...] Read more.
A fully differential multipath current-feedback instrumentation amplifier (CFIA) for a resistive bridge sensor readout integrated circuit (IC) is proposed. To reduce the CFIA’s own offset and 1/f noise, a chopper stabilization technique is implemented. To attenuate the output ripple caused by chopper up-modulation, a ripple reduction loop (RRL) is employed. A multipath architecture is implemented to compensate for the notch in the chopping frequency band of the transfer function. To prevent performance degradation resulting from external offset, a 12-bit R-2R digital-to-analog converter (DAC) is employed. The proposed CFIA has an adjustable gain of 16–44 dB with 5-bit programmable resistors. The proposed resistive sensor readout IC is implemented in a 0.18 μm complementary metal-oxide-semiconductor (CMOS) process. The CFIA draws 169 μA currents from a 3.3 V supply. The simulated input-referred noise and noise efficiency factor (NEF) are 28.3 nV/√Hz and 14.2, respectively. The simulated common-mode rejection ratio (CMRR) is 162 dB, and the power supply rejection ratio (PSRR) is 112 dB. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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18 pages, 327 KiB  
Article
Adaptive-Uniform-Experimental-Design-Based Fractional-Order Particle Swarm Optimizer with Non-Linear Time-Varying Evolution
by Po-Yuan Yang, Fu-I Chou, Jinn-Tsong Tsai and Jyh-Horng Chou
Appl. Sci. 2019, 9(24), 5537; https://doi.org/10.3390/app9245537 - 16 Dec 2019
Cited by 11 | Viewed by 2771
Abstract
An adaptive-uniform-experimental-design-based fractional particle swarm optimizer (AUFPSO) with non-linear time-varying evolution (NTE) is proposed. A particle swarm optimizer (PSO) is an excellent evolutionary algorithm due to its simple structure and rapid convergence. Nevertheless, PSO has notable drawbacks. Although many proposed methods and strategies [...] Read more.
An adaptive-uniform-experimental-design-based fractional particle swarm optimizer (AUFPSO) with non-linear time-varying evolution (NTE) is proposed. A particle swarm optimizer (PSO) is an excellent evolutionary algorithm due to its simple structure and rapid convergence. Nevertheless, PSO has notable drawbacks. Although many proposed methods and strategies have enhanced its effectiveness and performance, PSO is limited by its tendency to fall into local optima and its tendency to obtain different solutions in each search (i.e., its weak robustness). Introducing fractional-order calculus in PSO (FPSO) can correct the order of the velocity derivative for each particle, which enhances the diversity and algorithmic effectiveness. This study used NTE of the order of the velocity derivative, inertia weight, cognitive parameter, and social parameter in an FPSO used to search for a global optimal solution. To obtain the best combination of FPSO and NTE, an adaptive uniform experimental design (AUED) method was used to deal with this essential issue. The AUED method integrates a uniform layout with the best combination phase and a stepwise ratio to assist in selecting the best combination for FPSO-NTE. Experimental applications in 15 global numerical optimization problems confirmed that the AUFPSO-NTE had a better performance and robustness than existing PSO-related algorithms. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
11 pages, 2493 KiB  
Article
Investigation of Strain of Steel Reinforcement of Modular Flexural Member at Discontinuity Interface
by Jongho Park, Hae-Kyun Lee, Sun-Kyu Park, Jinwoong Choi and Sungnam Hong
Appl. Sci. 2019, 9(22), 4922; https://doi.org/10.3390/app9224922 - 15 Nov 2019
Viewed by 2260
Abstract
The modular structure has a discontinuity owing to the joint between the modules; thus, structural behavior verification is required. In this study, the tensile behavior of a steel reinforcement at the discontinuity interface was evaluated in the joint of a modular flexural member. [...] Read more.
The modular structure has a discontinuity owing to the joint between the modules; thus, structural behavior verification is required. In this study, the tensile behavior of a steel reinforcement at the discontinuity interface was evaluated in the joint of a modular flexural member. The modular specimen was fabricated with a 400 mm joint, and an integral specimen was fabricated with the same specifications as the modular specimen, without a joint. The largest crack width of the integral specimen was measured at the center of the beam, and that of the modular specimen was measured at the discontinuity interface. The maximum crack width of the modular specimen was greater than that of the integral specimen. The strain of the steel reinforcement was estimated using the measured crack width and six formulas for evaluating the crack width. The estimated strain of the modular specimen was higher than that of the integral specimen, and the deformation of the steel reinforcement at the discontinuity interface was accelerated with the increasing load. Therefore, the tensile load was concentrated at the discontinuity interface in the modular specimen, and the steel reinforcement at the discontinuity interface was likely to yield earlier than the integral specimen. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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19 pages, 8115 KiB  
Article
Traffic Light Cycle Configuration of Single Intersection Based on Modified Q-Learning
by Hung-Chi Chu, Yi-Xiang Liao, Lin-huang Chang and Yen-Hsi Lee
Appl. Sci. 2019, 9(21), 4558; https://doi.org/10.3390/app9214558 - 27 Oct 2019
Cited by 9 | Viewed by 4372
Abstract
In recent years, within large cities with a high population density, traffic congestion has become more and more serious, resulting in increased emissions of vehicles and reducing the efficiency of urban operations. Many factors have caused traffic congestion, such as insufficient road capacity, [...] Read more.
In recent years, within large cities with a high population density, traffic congestion has become more and more serious, resulting in increased emissions of vehicles and reducing the efficiency of urban operations. Many factors have caused traffic congestion, such as insufficient road capacity, high vehicle density, poor urban traffic planning and inconsistent traffic light cycle configuration. Among these factors, the problems of traffic light cycle configuration are the focal points of this paper. If traffic lights can adjust the cycle dynamically with traffic data, it will reduce degrees of traffic congestion significantly. Therefore, a modified mechanism based on Q-Learning to optimize traffic light cycle configuration is proposed to obtain lower average vehicle delay time, while keeping significantly fewer processing steps. The experimental results will show that the number of processing steps of this proposed mechanism is 11.76 times fewer than that of the exhaustive search scheme, and also that the average vehicle delay is only slightly lower than that of the exhaustive search scheme by 5.4%. Therefore the proposed modified Q-learning mechanism will be capable of reducing the degrees of traffic congestions effectively by minimizing processing steps. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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17 pages, 1783 KiB  
Article
Construction and Numerical Realization of a Magnetization Model for a Magnetostrictive Actuator Based on a Free Energy Hysteresis Model
by Zhen Yu, Chen-yang Zhang, Jing-xian Yu, Zhang Dang and Min Zhou
Appl. Sci. 2019, 9(18), 3691; https://doi.org/10.3390/app9183691 - 5 Sep 2019
Cited by 3 | Viewed by 2432
Abstract
Giant magnetostrictive actuators (GMA) driven by giant magnetostrictive material (GMM) has some advantages such as a large strain, high precision, large driving force, fast response, high reliability, and so on, and it has become the research hotspot in the field of microdrives. Research [...] Read more.
Giant magnetostrictive actuators (GMA) driven by giant magnetostrictive material (GMM) has some advantages such as a large strain, high precision, large driving force, fast response, high reliability, and so on, and it has become the research hotspot in the field of microdrives. Research shows there is a nonlinear, intrinsic relationship between the output signal and the input signal of giant magnetostrictive actuators because of the strong coupling characteristics between the machine, electromagnetic field, and heat. It is very complicated to construct its nonlinear eigenmodel, and it is the basis of the practical process of giant magnetostrictive material to construct its nonlinear eigenmodel. Aiming at the design of giant magnetostrictive actuators, the magnetization model based on a free-energy hysteresis model has been deeply researched, constructed, and put forward by Smith, which combines Helmholtz–Gibbs free energy and statistical distribution theory, to simulate the hysteresis model at medium or high driving strengths. Its main input and output parameters include magnetic field strength, magnetization, and mechanical strain. Then, numerical realization and verification of the magnetization model are done by the Gauss–Legendre integral discretization method. The results show that the magnetization model and its numerical method are correct, and the research results provide a theoretical basis for the engineering application of giant magnetostrictive material and optimized structure of giant magnetostrictive material actuators, which have an important practical application value. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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19 pages, 5449 KiB  
Article
Fiber Bragg Gratings Based Cyclic Strain Measuring of Weld Toes of Cruciform Joints
by Guoqian Wei, Shanshan Li, Yongxing Guo and Zhang Dang
Appl. Sci. 2019, 9(14), 2939; https://doi.org/10.3390/app9142939 - 23 Jul 2019
Cited by 5 | Viewed by 3873
Abstract
The real weld toe geometry is generally not mathematically perfect, resulting in obvious stress concentration effects, both on the weld section and along the longitudinal direction of the weld toe. The true stress-strain state at the local weld toe directly affects the fatigue [...] Read more.
The real weld toe geometry is generally not mathematically perfect, resulting in obvious stress concentration effects, both on the weld section and along the longitudinal direction of the weld toe. The true stress-strain state at the local weld toe directly affects the fatigue performance and behavior of the welded structure. Therefore, a Fiber Bragg Grating (FBG) sensor based method for testing the cyclic strain at the weld toe was proposed. Cruciform welded joints were fabricated as specimens on which FBG sensors were arranged at several characteristic points along the weld toe curve. Strains at all the characteristic points under cyclic tensile load were measured and recorded, which showed the proposed measuring method could accurately obtain the complete local strain time histories along the weld toe. The strain time histories clearly reflected the cyclic hardening phenomenon in the early stage and the plastic yielding phenomenon in the final stage. Furthermore, based on the cyclic stress-strain constitutive model of the weld material, the stress-strain response curves of all the characteristic points were drawn. Combined with the fatigue fracture morphology, the mechanism of the unsynchronized initiation of the multiple cracks in the weld toe was investigated. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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24 pages, 4714 KiB  
Article
Effective Assessment of Inelastic Torsional Deformation of Plan-Asymmetric Shear Wall Systems
by Taehyu Ha, Sung-Gul Hong, Bong-Ho Cho and Dae-Jin Kim
Appl. Sci. 2019, 9(14), 2814; https://doi.org/10.3390/app9142814 - 14 Jul 2019
Cited by 7 | Viewed by 3997
Abstract
Torsional deformation may occur in plan-asymmetric wall structures during seismic events. In most current seismic design codes, the torsional deformation is handled using the concept of design eccentricity, in which design loads may be excessively amplified. This approach has limitations in accurately estimating [...] Read more.
Torsional deformation may occur in plan-asymmetric wall structures during seismic events. In most current seismic design codes, the torsional deformation is handled using the concept of design eccentricity, in which design loads may be excessively amplified. This approach has limitations in accurately estimating the torsional deformation of the plan-asymmetric structures, mainly because it is based on linear elastic material behavior. In this paper, we propose a simple method that can accurately evaluate the inelastic lateral displacement and rotation of plan-asymmetric wall structures and is suitable for use in the displacement-based design method. The effectiveness of the proposed method is verified by comparing its predictions with the results of rigorous time history analyses for a model problem. The comparison shows that the proposed method is able to provide accurate estimates of the inelastic torsional deformation for the plan-asymmetric wall system, while requiring less computational cost than the time history analysis. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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21 pages, 11122 KiB  
Article
Structural Performance of a New Blind-Bolted Frame Modular Beam-Column Connection under Lateral Loading
by Bong-Ho Cho, Jae-Sub Lee, Hongjin Kim and Dae-Jin Kim
Appl. Sci. 2019, 9(9), 1929; https://doi.org/10.3390/app9091929 - 10 May 2019
Cited by 41 | Viewed by 6052
Abstract
This study proposes an effective steel frame modular system and evaluates the structural performance of its beam-column connection through experimental and analytical work. The new steel frame modular system utilizes the blind bolts, which allow free access to the structural members of the [...] Read more.
This study proposes an effective steel frame modular system and evaluates the structural performance of its beam-column connection through experimental and analytical work. The new steel frame modular system utilizes the blind bolts, which allow free access to the structural members of the closed cross-section. In addition, the new modular system is designed such that the strength of its beam members is considerably lower than that of its column members to implement the strong column-weak beam concept. In order to investigate the effectiveness of the proposed modular beam-column connection, two types of specimens were designed and tested. One of the two specimens has four knee brace members to increase the bending stiffness of the connection, while the other does not have these components. The applied load versus displacement curves are plotted for the two specimens, and their failure modes are identified. Finally, a simplified analytical model for the modular beam-column connection is proposed, and its effectiveness is validated by performing its push-over analysis and comparing its results with the test results. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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16 pages, 4206 KiB  
Article
Modeling a Dual-Mode Controller Design for a Quasi-Resonant Flyback Converter
by Ching-Chun Chuang, Chih-Chiang Hua, Chong-Yu Huang and Li-Kai Jhou
Appl. Sci. 2019, 9(9), 1860; https://doi.org/10.3390/app9091860 - 6 May 2019
Cited by 1 | Viewed by 3605
Abstract
The proposed system can overcome the disadvantage of a high peak current in quasi-resonant fly-back (QRF) converters when operated under heavy load conditions. The operating mode and control scheme of a QRF converter with dual-mode control were established and analyzed. The dual-mode control [...] Read more.
The proposed system can overcome the disadvantage of a high peak current in quasi-resonant fly-back (QRF) converters when operated under heavy load conditions. The operating mode and control scheme of a QRF converter with dual-mode control were established and analyzed. The dual-mode control scheme not only enabled a valley-switching detection technique that satisfied the zero-voltage switching condition but also provided a constant frequency mechanism to reduce the conduction loss in QRF converters when operated in a continuous conduction mode and under heavy load conditions. The small-signal equivalent circuit model of QRF converter circuits was constructed using an average approximation method. The technological advancement of a QRF converter with a dual-mode controller was presented in this study. The circuit simulation result of the proposed QRF converter with a mix control scheme proved that the derived circuit component parameters meet the requirements of the converter. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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10 pages, 1119 KiB  
Article
Inter-Sentence Segmentation of YouTube Subtitles Using Long-Short Term Memory (LSTM)
by Hye-Jeong Song, Hong-Ki Kim, Jong-Dae Kim, Chan-Young Park and Yu-Seop Kim
Appl. Sci. 2019, 9(7), 1504; https://doi.org/10.3390/app9071504 - 11 Apr 2019
Cited by 17 | Viewed by 6812
Abstract
Recently, with the development of Speech to Text, which converts voice to text, and machine translation, technologies for simultaneously translating the captions of video into other languages have been developed. Using this, YouTube, a video-sharing site, provides captions in many languages. Currently, the [...] Read more.
Recently, with the development of Speech to Text, which converts voice to text, and machine translation, technologies for simultaneously translating the captions of video into other languages have been developed. Using this, YouTube, a video-sharing site, provides captions in many languages. Currently, the automatic caption system extracts voice data when uploading a video and provides a subtitle file converted into text. This method creates subtitles suitable for the running time. However, when extracting subtitles from video using Speech to Text, it is impossible to accurately translate the sentence because all sentences are generated without periods. Since the generated subtitles are separated by time units rather than sentence units, and are translated, it is very difficult to understand the translation result as a whole. In this paper, we propose a method to divide text into sentences and generate period marks to improve the accuracy of automatic translation of English subtitles. For this study, we use the 27,826 sentence subtitles provided by Stanford University’s courses as data. Since this lecture video provides complete sentence caption data, it can be used as training data by transforming the subtitles into general YouTube-like caption data. We build a model with the training data using the LSTM-RNN (Long-Short Term Memory – Recurrent Neural Networks) and predict the position of the period mark, resulting in prediction accuracy of 70.84%. Our research will provide people with more accurate translations of subtitles. In addition, we expect that language barriers in online education will be more easily broken by achieving more accurate translations of numerous video lectures in English. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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12 pages, 5037 KiB  
Article
Integrated Inundation Modeling of Flooded Water in Coastal Cities
by Eun Taek Shin, Jaehyun Shin, Dong Sop Rhee, Hyung-Jun Kim and Chang Geun Song
Appl. Sci. 2019, 9(7), 1313; https://doi.org/10.3390/app9071313 - 29 Mar 2019
Cited by 10 | Viewed by 3067
Abstract
Climate change has increased the damage caused by subtropical rainfall and typhoons in coastal areas. Major flooding factors in coastal areas can be classified as storm surges, river inundation, and inland submergence. Because previous studies usually applied a linear sum of individual inundation [...] Read more.
Climate change has increased the damage caused by subtropical rainfall and typhoons in coastal areas. Major flooding factors in coastal areas can be classified as storm surges, river inundation, and inland submergence. Because previous studies usually applied a linear sum of individual inundation components to predict comprehensive flood phenomena, this approach does not consider weighted effects associated with the simultaneous occurrence of complex flooding. In this study, a series of comprehensive flood simulations were performed using two numerical models: HDM-2D and FLUval Modeling ENgine (FLUMEN). The results revealed that an integrated flood analysis considering the effects of inundation flooding, river flooding, and coastal flooding required evaluation of the risk of flooding in coastal cities. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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11 pages, 2738 KiB  
Article
Inundation Risk Assessment of Underground Space Using Consequence-Probability Matrix
by Yong-sik Han, Eun Taek Shin, Tae Soo Eum and Chang Geun Song
Appl. Sci. 2019, 9(6), 1196; https://doi.org/10.3390/app9061196 - 21 Mar 2019
Cited by 13 | Viewed by 3739
Abstract
Increases in the frequency and severity of extreme rainfall might cause catastrophic submergence of underground spaces. Therefore, it is essential to predict the flood risk for proactive design. This study presents the methodology of acquiring risk level considering both flood intensity and evacuation [...] Read more.
Increases in the frequency and severity of extreme rainfall might cause catastrophic submergence of underground spaces. Therefore, it is essential to predict the flood risk for proactive design. This study presents the methodology of acquiring risk level considering both flood intensity and evacuation difficulty. The flood momentum was computed by a 2D hydraulic flow model, and the flood intensity (FI) was employed to evaluate the consequence of flooding. To investigate the level of evacuation difficulty, the spatial layout of rooms, together with walking speed, were considered in the risk analysis process. If stormwater runoff enters an underground space, zones far away from the inlet usually have low risk levels. However, when the level of evacuation difficulty was considered, the risk level was dependent on the evacuation distance and location of the inlet and exit. If people are in zones with a risk level of 4 or 5, a rapid evacuation is necessary for preventing human casualties. The proposed methodology incorporated with the inundation model can be applied to any underground space regardless of the location of stairs, the number of exits, shape of rooms, or layout of the floor. Consequently, it will contribute to mitigating flood damage in an underground space. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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10 pages, 1798 KiB  
Article
A Web Service for Evaluating the Level of Speech in Korean
by Hye-Jeong Song, Ji-Eun Choi, Yoon-Kyoung Lee, Ji Hye Yoon, Jong-Dae Kim, Chan-Young Park and Yu-Seop Kim
Appl. Sci. 2019, 9(3), 594; https://doi.org/10.3390/app9030594 - 11 Feb 2019
Cited by 4 | Viewed by 3317
Abstract
Speaking is a way for humans to communicate with others using language. The ability to speak according to the speaker is very diverse. In general, language skills improve as intelligence improves. Therefore, it is known that the analysis of a speaker’s utterances is [...] Read more.
Speaking is a way for humans to communicate with others using language. The ability to speak according to the speaker is very diverse. In general, language skills improve as intelligence improves. Therefore, it is known that the analysis of a speaker’s utterances is a good tool to evaluate the intellectual maturity of the speaker. Until recently, these evaluations have been done manually based on the experience of a handful of experts, but this approach is not only time consuming and costly, but also highly subjective. In this paper, we propose a Korean automatic speech analysis system based on Natural Language Processing (NLP) and web service to solve this problem. For this study, we constructed a web service based on Django to respond to the requests of various users. When a user delivered a transcription file of utterances to the server via the web, the server analyzed the speech ability of the speaker based on various indicators. The server compared the transcription file with the language ability indicators of persons of the same age as the speaker and displayed the result immediately to the user. In this study, we used KoNLPy, a Korean language-processing tool. The automatic speech analysis service analyzed not only the overall language ability of the speaker but also individual domains such as sentence completion ability and vocabulary ability. In addition, a faster and immediate service was made possible without sacrificing accuracy as compared to human analysis. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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17 pages, 4877 KiB  
Article
Investigation of an Explosion at a Styrene Plant with Alkylation Reactor Feed Furnace
by Yao-Chang Wu, Bin Laiwang and Chi-Min Shu
Appl. Sci. 2019, 9(3), 503; https://doi.org/10.3390/app9030503 - 1 Feb 2019
Cited by 8 | Viewed by 9291
Abstract
To prevent and mitigate chemical risks in the petrochemical industry, such as fires and spillage, process safety management (PSM), is essential, especially where flammable, corrosive, explosive, toxic, or otherwise dangerous chemicals are used. We investigated process safety (PS) between man–machine (material equipment) and [...] Read more.
To prevent and mitigate chemical risks in the petrochemical industry, such as fires and spillage, process safety management (PSM), is essential, especially where flammable, corrosive, explosive, toxic, or otherwise dangerous chemicals are used. We investigated process safety (PS) between man–machine (material equipment) and environmental interfaces by using process hazard analysis (PHA) and fault tree analysis (FTA). By analyzing the data obtained through machinery and mechanical integrity (MI), pre-startup safety review (PSSR), current operating modes, and areal locations of hazardous atmospheres (ALOHA) simulations of the disaster’s aftermath, the cause of the styrene plant accident was found to be the fuel furnace (F101) switching process. Although the furnace had been extinguished, fuel continued to enter the furnace, and it was exposed to a high-temperature surface, resulting in the flashing ignition of the C4 fuel. The plan-do-check-act (PDCA) management model can be used to forestall the system from accident, and it is used to improve the proposal and develop countermeasures that would increase PSM performance and substantially lessen the impact of the thermal hazard. Disasters are often attributable to the unsafe state of machinery, equipment, or the environment, dangerous behaviors of the operator, and the lack of a thorough management system. It is anticipated that the investigation and analysis of the accident would not only find the real cause of the disaster but also lead to the establishment of better effective solutions for common safety problems. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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8 pages, 5338 KiB  
Article
Effects of Connection Type between Surface Vessel and Submersible Propeller on Motion Performance of Wave Glider
by Zhanxia Feng, Zongyu Chang, Zhongqiang Zheng and Panfeng Wang
Appl. Sci. 2018, 8(12), 2467; https://doi.org/10.3390/app8122467 - 3 Dec 2018
Cited by 7 | Viewed by 2919
Abstract
Wave Glider is an autonomous surface vehicle that directly uses wave energy to generate forward power and has been widely used in marine survey and observation. Wave Glider is composed of surface vessel, submersible propeller and the connection structure between them. Connection types [...] Read more.
Wave Glider is an autonomous surface vehicle that directly uses wave energy to generate forward power and has been widely used in marine survey and observation. Wave Glider is composed of surface vessel, submersible propeller and the connection structure between them. Connection types are thought to be related to the performance of Wave Glider closely. In this paper, the effects of the connection structure between the surface vessel and the submersible propeller on the motion performance of the Wave Glider are studied. Several connection types such as rigid rod, cable, multi-link chain and elastic rod are applied to connect the surface vessel and the submersible propeller. The models of connection structures are developed respectively. Among them, cable model is established with a finite number of small cylinders, which connected by spring and damping elements; multi-link chain can be seen as hinged by multiple rigid rods; elastic rod model can be looked on as several segments linked with elastic components. Considering the connection characteristics, the integrated dynamic models are established by applying multi-body dynamics software ADAMS (Automatic Dynamic Analysis of Mechanical Systems) with consideration of the hydrodynamic forces on different components of Wave Glider. The propulsion performance of the Wave Glider is calculated by using numerical method, and the simulation results showed that the difference of propulsion performance with different connection types of the Wave Glider is slightly. But serious impacts can occur on the connections of rigid rod and multi-link chain. They can lead to serious extra load on the structure of Wave Glider. From the engineering practice of Wave Glider application, the cable connection is more convenient to transport, deploy, recover and store. It is also the generous connection type for wave glider. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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24 pages, 7822 KiB  
Article
A Novel Hybrid Boundary-Type Meshless Method for Solving Heat Conduction Problems in Layered Materials
by Jing-En Xiao, Cheng-Yu Ku, Wei-Po Huang, Yan Su and Yung-Hsien Tsai
Appl. Sci. 2018, 8(10), 1887; https://doi.org/10.3390/app8101887 - 11 Oct 2018
Cited by 6 | Viewed by 2828
Abstract
In this article, we propose a novel meshless method for solving two-dimensional stationary heat conduction problems in layered materials. The proposed method is a recently developed boundary-type meshless method which combines the collocation scheme from the method of fundamental solutions (MFS) with the [...] Read more.
In this article, we propose a novel meshless method for solving two-dimensional stationary heat conduction problems in layered materials. The proposed method is a recently developed boundary-type meshless method which combines the collocation scheme from the method of fundamental solutions (MFS) with the collocation Trefftz method (CTM) to improve the applicability of the method for solving boundary value problems. Particular non-singular basis functions from cylindrical harmonics are adopted in which the numerical approximation is based on the superposition principle using the non-singular basis functions expressed in terms of many source points. For the modeling of multi-layer composite materials, we adopted the domain decomposition method (DDM), which splits the domain into smaller subdomains. The continuity of the flux and the temperature has to be satisfied at the interface of subdomains for the problem. The validity of the proposed method is investigated for several test problems. Numerical applications were also carried out. Comparison of the proposed method with other meshless methods showed that it is highly accurate and computationally efficient for modeling heat conduction problems, especially in heterogeneous multi-layer composite materials. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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