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Selected Papers from the ICMR 2019
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Selected Papers from the ICMR 2019

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

Deadline for manuscript submissions: closed (30 November 2019) | Viewed by 94054

Special Issue Editors

Prof. Dr. Sang-Jae Kim

E-Mail Website
Guest Editor
Department of Mechatronics Engineering, Jeju National University, Jeju, Jeju-si 63243, Republic of Korea
Interests: self-charging power cell; hybrid fuel cell; energy harvesting; nanogenerator; nanobiosensor
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Hyunseok Oh

E-Mail Website
Guest Editor
School of Mechanical Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
Interests: prognostics and health management (PHM); industrial artificial intelligence (AI); reliability assessment
Special Issues, Collections and Topics in MDPI journals
Dr. Sunghan Kim

E-Mail Website
Guest Editor
School of Mechanical Engineering, Chung-Ang University, Dongjak-gu, Seoul 06974, Republic of Korea
Interests: bionanocomposties; micro/nanomechanics; sensors; nanofluid; surface/interface engineering; tribology; finite element analysis; hydrogen energy
Special Issues, Collections and Topics in MDPI journals
Dr. Hoyong Lee

E-Mail Website
Guest Editor
Department of Defense & Science Technology, Gwangju University, Gwangju 61743, Korea
Interests: failure analysis; magnetic sensors; nondestructive testing and evaluation; mechanical reliability of electronics system
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Reliability is an important consideration across various industries, including electronics, automotive, heavy-chemical industries, and power plants. The international competitiveness of those industries in a globalized economy is closely tied to the high reliability of their technologies, products, and materials.

In this context, this special issue aims to showcase the latest reliability, and Prognostics and Health Management (PHM) research trends, including their applications, advanced technologies and processes for reliability assessment, advanced theoretical and experimental reliability analysis, and other related topics.

This special issue welcomes full article submissions from presenters, and speakers at the 5th International Conference on Materials and Reliability (ICMR 2019), held November 27-29, 2019 in Jeju, Republic of Korea.

Prof. Sang-Jae Kim
Dr. Hyunseok Oh
Dr. Sunghan Kim
Dr. Hoyong Lee
Guest Editors

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Keywords

  • Reliability
  • Prognostics and Health Management
  • Advanced Materials
  • Material Characterization
  • Risk Assessment
  • Big Data Analytics
  • Smart Manufacturing
  • Accelerated Life Testing

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Published Papers (22 papers)

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Research

16 pages, 3549 KiB  
Article
Study on the Shifting Quality of the CVT Tractor under Hydraulic System Failure
by Guangming Wang, Yue Song, Jiabo Wang, Wanqiang Chen, Yunlian Cao and Jinxing Wang
Appl. Sci. 2020, 10(2), 681; https://doi.org/10.3390/app10020681 - 18 Jan 2020
Cited by 12 | Viewed by 4007
Abstract
The failure of a hydraulic system will affect the shifting quality and driving safety of a CVT tractor. In order to reveal the response of the tractor under different hydraulic system failures without destroying the transmission, the following methods are proposed in this [...] Read more.
The failure of a hydraulic system will affect the shifting quality and driving safety of a CVT tractor. In order to reveal the response of the tractor under different hydraulic system failures without destroying the transmission, the following methods are proposed in this paper: firstly, building the simulation model of CVT; secondly, building a test bench to test and verify the transmission model to ensure that the simulation model can accurately predict the response of CVT under different clutch oil pressures; thirdly, obtaining the fault oil pressure data without starting the engine and taking the data of fault oil pressure as the input variable of the simulation model; finally, obtaining the response of the CVT tractor under different hydraulic system failures by simulation. It is found that the damage of the seal ring inside the rotary joint has little effect on shifting quality; oil way block can lead to greater shift impact; when seal ring damage and oil way block occur together, the clutch cannot reach the minimum working pressure; clutch piston jamming and oil leak can cause power interruption of the tractor. The results show that it is feasible to study the response of CVT in fault mode by simulation. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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13 pages, 2008 KiB  
Article
A Response-Adaptive Method for Design of Validation Experiments in Computational Mechanics
by Byung C. Jung, Yun-Ho Shin, Sang Hyuk Lee, Young Cheol Huh and Hyunseok Oh
Appl. Sci. 2020, 10(2), 647; https://doi.org/10.3390/app10020647 - 16 Jan 2020
Viewed by 2454
Abstract
For model verification and validation (V & V) in computational mechanics, a hypothesis test for the validity check (HTVC) is useful, in particular, with a limited number of experimental data. However, HTVC does not address how type I and II errors can be [...] Read more.
For model verification and validation (V & V) in computational mechanics, a hypothesis test for the validity check (HTVC) is useful, in particular, with a limited number of experimental data. However, HTVC does not address how type I and II errors can be reduced when additional resources for sampling become available. For the validation of computational models of safety-related and mission-critical systems, it is challenging to design experiments so that type II error is reduced while maintaining type I error at an acceptable level. To address the challenge, this paper proposes a new method to design validation experiments, response-adaptive experiment design (RAED). The RAED method adaptively selects the next experimental condition from among candidates of various operating conditions (experimental settings). RAED consists of six key steps: (1) define experimental conditions, (2) obtain experimental data, (3) calculate u-values, (4) compute the area metric, (5) select the next experimental condition, and (6) obtain additional experimental datum. To demonstrate the effectiveness of the RAED method, a case study of a numerical example is shown. It is demonstrated that additional experimental data obtained through the RAED method can reduce type II error in hypothesis testing and increase the probability of rejecting an invalid computational model. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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11 pages, 5863 KiB  
Article
Learning Collision Situation to Convolutional Neural Network Using Collision Grid Map Based on Probability Scheme
by Jun Hyeong Jo and Chang-bae Moon
Appl. Sci. 2020, 10(2), 617; https://doi.org/10.3390/app10020617 - 15 Jan 2020
Cited by 2 | Viewed by 2387
Abstract
In this paper, a Collision Grid Map (CGM) is proposed by using 3d point cloud data to predict the collision between the cattle and the end effector of the manipulator in the barn environment. The Generated Collision Grid Map using x-y plane and [...] Read more.
In this paper, a Collision Grid Map (CGM) is proposed by using 3d point cloud data to predict the collision between the cattle and the end effector of the manipulator in the barn environment. The Generated Collision Grid Map using x-y plane and depth z data in 3D point cloud data is applied to a Convolutional Neural Network to predict a collision situation. There is an invariant of the permutation problem, which is not efficiently learned in occurring matter of different orders when 3d point cloud data is applied to Convolutional Neural Network. The Collision Grid Map is generated by point cloud data based on the probability method. The Collision Grid Map scheme is composed of a 2-channel. The first channel is constructed by location data in the x-y plane. The second channel is composed of depth data in the z-direction. 3D point cloud is measured in a barn environment and created a Collision Grid Map. Then the generated Collision Grid Map is applied to the Convolutional Neural Network to predict the collision with cattle. The experimental results show that the proposed scheme is reliable and robust in a barn environment. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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8 pages, 940 KiB  
Article
Simplified Vibration PSD Synthesis Method for MIL-STD-810
by Jin Jang and Jong-Won Park
Appl. Sci. 2020, 10(2), 458; https://doi.org/10.3390/app10020458 - 8 Jan 2020
Cited by 10 | Viewed by 7074
Abstract
In MIL-STD-810, the environmental engineering consideration and laboratory tests by US military, the DP (damage potential) formula is used to calculate the fatigue damage by vibration environments which is a simplified version of a FDS (fatigue damage spectrum) formula. DP, however, was originally [...] Read more.
In MIL-STD-810, the environmental engineering consideration and laboratory tests by US military, the DP (damage potential) formula is used to calculate the fatigue damage by vibration environments which is a simplified version of a FDS (fatigue damage spectrum) formula. DP, however, was originally made for comparison between different test standards and is not an optimized formula for the synthesis of vibration environments. This paper presents the GRS (Gaussian Random Synthesis) formula for only vibration test synthesis featuring simplified DP formula and produce the same result as DP. Although the GRS provides insight into the synthesis of vibration tests, it must be used with care because it inherits the constraints of the original FDS formula. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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9 pages, 4355 KiB  
Article
Structural Colors Based on Amorphous Arrays Comprised Solely of Silica Particles
by Dae-San Choi, Ju-Hwan Choi and Chang-Yull Lee
Appl. Sci. 2020, 10(1), 420; https://doi.org/10.3390/app10010420 - 6 Jan 2020
Cited by 9 | Viewed by 4456
Abstract
In this study, structural colors were fabricated by producing an amorphous array with atypical silica particles. The colors were controlled by an array of silica particles with different sizes. In previous research, the process required inducement of the amorphous array, which was complex. [...] Read more.
In this study, structural colors were fabricated by producing an amorphous array with atypical silica particles. The colors were controlled by an array of silica particles with different sizes. In previous research, the process required inducement of the amorphous array, which was complex. Meanwhile, in this paper, we proposed a simple one-step process. First, spherical silica nanoparticles were synthesized using the sol-gel process of the Stöber method. Atypical silica particles that induced an amorphous array were produced by adding a small amount of phenol-formaldehyde resin. Subsequently, the colloidal silica was converted to a powder using a convection oven. The characteristics of the synthesized silica particles were confirmed using a scanning electron microscope (SEM). All the synthesized silica powders obtained structural colors. Finally, the silica powders were dispersed in deionized (DI) water and coated on a glass slide. We confirmed that the silica particles showed different structural colors depending on the size of the particles. We also found that the color was highly independent of the viewing angle. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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11 pages, 4614 KiB  
Article
Comparison of Tensile and Fatigue Properties of Copper Thin Film Depending on Process Method
by Hyeon-Gyu Min, Dong-Joong Kang and Jun-Hyub Park
Appl. Sci. 2020, 10(1), 388; https://doi.org/10.3390/app10010388 - 4 Jan 2020
Cited by 15 | Viewed by 6985
Abstract
In this study, tensile and fatigue tests were performed and analyzed to evaluate an influence of fabrication method on mechanical characteristics of copper thin film which widely used in flexible printed circuit board (FPCB). In general, manufacturing methods are known to affect the [...] Read more.
In this study, tensile and fatigue tests were performed and analyzed to evaluate an influence of fabrication method on mechanical characteristics of copper thin film which widely used in flexible printed circuit board (FPCB). In general, manufacturing methods are known to affect the mechanical properties of materials, especially for thin films. The copper thin film is manufactured by a rolling process or an electrodeposition process. Therefore, specimen for tensile and fatigue tests were fabricated using by etching process with the rolled and electrodeposited thin films. First, the tensile tests were performed to obtain the elastic modulus, 0.2% offset yield stress, and tensile strength of the rolled copper and the electrodeposited copper thin film. Second, the copper thin films in FPCB is most often subjected to mechanical or/and thermal cyclic loading. The fatigue tests were performed to compare the fatigue characteristics and to evaluate an influence of fabrication method. Tensile test results showed that the elastic modulus was similar for each process, but the 0.2% yield strength and ultimate tensile strength were greater in the rolling process. In addition, the fatigue test results show that the copper thin films by the rolling process are better than by the electrodeposition process in fatigue life in all region. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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15 pages, 2683 KiB  
Article
Active Vibration Suppression of Stiffened Composite Panels with Piezoelectric Materials under Blast Loads
by Chang-Yull Lee, Jin-Young Jung and Se-Min Jeong
Appl. Sci. 2020, 10(1), 387; https://doi.org/10.3390/app10010387 - 4 Jan 2020
Cited by 3 | Viewed by 2252
Abstract
Transient responses of stiffened panels with piezoelectric sensors and actuators are studied under normal blast loads. The air vehicles could be exposed to blast pulses generated by an explosion or shock-wave disturbances. Thus, active vibration suppression of the vehicles is important under blast [...] Read more.
Transient responses of stiffened panels with piezoelectric sensors and actuators are studied under normal blast loads. The air vehicles could be exposed to blast pulses generated by an explosion or shock-wave disturbances. Thus, active vibration suppression of the vehicles is important under blast loadings. The structural model is designed as a laminated composite panel with lead zirconate titanate (PZT) piezoceramic layers embedded on both top and bottom surfaces. A uniformly distributed blast load is assumed over the whole of the panel surface. The first-order shear deformation theory of plate is adopted, and the extended Hamilton’s principle is applied to derive the equations of motions. The numerical model is verified by the comparison with previous data. Using linear quadratic regulator (LQR) control algorithm, vibration characteristics and dynamic responses are compared. As piezoelectric patches are attached on the whole of the surface, the effect of the stiffener’s location is studied. Furthermore, the influences of the patch’s positions are also investigated through subjection to the blast wave. From various results, in order to get the best control performances, the research aims to find the optimum position of sensor and actuator pairs that is most effective under blast load environments. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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13 pages, 3995 KiB  
Article
Bulletproof Performance of Composite Plate Fabricated Using Shear Thickening Fluid and Natural Fiber Paper
by Hyeonho Cho, Jongsuk Lee, Sungjin Hong and Sunghan Kim
Appl. Sci. 2020, 10(1), 88; https://doi.org/10.3390/app10010088 - 20 Dec 2019
Cited by 12 | Viewed by 4741
Abstract
In the munitions industry, there have been considerable efforts spent to develop low-cost, simply fabricated, easily wearable, and biocompatible bulletproof armors. Recently, long fiber-reinforced composites and shear thickening fluids (STFs) were inceptively utilized to improve bulletproof performance with solid or fabric materials. In [...] Read more.
In the munitions industry, there have been considerable efforts spent to develop low-cost, simply fabricated, easily wearable, and biocompatible bulletproof armors. Recently, long fiber-reinforced composites and shear thickening fluids (STFs) were inceptively utilized to improve bulletproof performance with solid or fabric materials. In this study, Hanji, a cornstarch suspension, Korean traditional long fiber paper, and a well-known STF, respectively, were examined for bulletproof applications to evaluate their own effects on bulletproof performance; tests were carried out in the field and finite element analysis (FEA) was performed to evaluate the behavior of materials regarding with perforated clay areas from in-field tests. It was found that both Hanji and STF influenced the bullet penetration by two factors, namely the momentum of bullet and stress propagation. The cornstarch suspension, rather than Hanji, showed outstanding performance in decreasing the linear velocity of the bullet and minimized the stress propagation to the protecting object. Thus, although STF performed a key role in bulletproof performance, Hanji also proved to be a suitable material as an exterior covering for absorbing the initial impact stress and maintaining the durability and stability of the armor itself. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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22 pages, 12775 KiB  
Article
Development and Evaluation of Crack Band Model Implemented Progressive Failure Analysis Method for Notched Composite Laminate
by Donghyun Yoon, Sangdeok Kim, Jaehoon Kim and Youngdae Doh
Appl. Sci. 2019, 9(24), 5572; https://doi.org/10.3390/app9245572 - 17 Dec 2019
Cited by 12 | Viewed by 4712
Abstract
Progressive failure analysis (PFA) is widely used to predict the failure behavior of composite materials. As a structure becomes more complex with discontinuities, prediction of failure becomes more difficult and mesh dependence must be taken into account. In this study, a PFA model [...] Read more.
Progressive failure analysis (PFA) is widely used to predict the failure behavior of composite materials. As a structure becomes more complex with discontinuities, prediction of failure becomes more difficult and mesh dependence must be taken into account. In this study, a PFA model was developed using the Hashin failure criterion and crack band model. The failure initiation was evaluated using the Hashin failure criterion. If failure initiation occurred, the damage variables at each failure mode (fiber tension and compression; matrix tension and compression) were calculated according to linear softening degradation and they were then used to derive the damaged stiffness matrix. This matrix reflected a degraded material, and PFA was continued until the damage variables became “1,” implying complete material failure. A series of processes were performed using the finite element method program ABAQUS with a user-defined material subroutine. To evaluate the proposed PFA model, experimental results of open-hole composite laminate tests were compared with the obtained numerical results. The strain behaviors were compared using a digital image correlation system. The obtained numerical results were in good agreement with the experimental ones. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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11 pages, 3243 KiB  
Article
Effect of Corrosion Characteristics on Long-Term Aging of Austenitic 304 Steel
by Chaeeul Huh, Seongbin An, Minsuk Kim and Chungseok Kim
Appl. Sci. 2019, 9(24), 5557; https://doi.org/10.3390/app9245557 - 17 Dec 2019
Cited by 4 | Viewed by 3315
Abstract
The objective of this study is to investigate the effect of long-term aging on electrochemical corrosion characteristics of austenitic AISI 304 steel. AISI 304 steel was subjected to aging treatment for an extended period at 700 °C up to a maximum of 10,000 [...] Read more.
The objective of this study is to investigate the effect of long-term aging on electrochemical corrosion characteristics of austenitic AISI 304 steel. AISI 304 steel was subjected to aging treatment for an extended period at 700 °C up to a maximum of 10,000 h. The variation in the microstructure of aged specimens was observed with an optical microscope (OM) and a scanning electron microscope (SEM). The electrochemical polarization test was conducted to obtain the corrosion current density (Icorr) and corrosion potential (Ecorr). The metastable intermetallic M23C6 carbides generated in the vicinity of γ/γ grain boundaries and coarsened with aging time. The δ-ferrite island decomposed into σ-phase and M23C6 carbide with an aging time increase. As the aging time increased, the current density increased, but the corrosion potential of the austenitized specimen exhibited a minimum value of 0.04 μA/cm2. The highest pitting resistance exhibited at the austenitized specimen due to the absence of carbides. Consequently, the corrosion resistance of austenitic AISI 304 steel decreases with long-term aging time. The microstructural analyses well support this result. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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23 pages, 8660 KiB  
Article
Thermomechanical Performance of Bio-Inspired Corrugated-Core Sandwich Structure for a Thermal Protection System Panel
by Vinh Tung Le and Nam Seo Goo
Appl. Sci. 2019, 9(24), 5541; https://doi.org/10.3390/app9245541 - 16 Dec 2019
Cited by 23 | Viewed by 5698
Abstract
A skin structure for thermal protection is one of the most interesting components that needs to be considered in the design of a hypersonic vehicle. The thermal protection structure, if a dense structure is used, is heavy and has a large heat conduction [...] Read more.
A skin structure for thermal protection is one of the most interesting components that needs to be considered in the design of a hypersonic vehicle. The thermal protection structure, if a dense structure is used, is heavy and has a large heat conduction path. Thus, a lightweight, high strength structure is preferable. Currently, for designing a lightweight structure with high strength, natural materials are of great interest for achieving low density, high strength, and toughness. This paper presents bio-inspired lightweight structures that ensure high strength for a thermal protection system (TPS). A sinusoidal shape inspired by the microstructure of the dactyl club of Odontodactylus scyllarus, known as the peacock mantis shrimp, is presented with two different geometries, a unidirectionally corrugated core sandwich structure (UCS) and a bidirectionally corrugated core sandwich structure (BCS). Thermomechanical analysis of the two corrugated core structures is performed under simulated aerodynamic heating, and the total deflection and thermal stress are presented. The maximum deflection of the present sandwich structure throughout a mission flight was 1.74 mm for the UCS and 2.04 mm for the BCS. Compared with the dense structure used for the skin structure of the TPS, the bio-inspired corrugated core sandwich structures achieved about a 65% weight reduction, while the deflections still satisfied the limits for delaying the hypersonic boundary layer transition. Moreover, we first fabricated the BCS to test the thermomechanical behaviors under a thermal load. Finally, we examined the influence of the core thickness, face-sheet thickness, and emittance in the simulation model to identify appropriate structural parameters in the TPS optimization. The present corrugated core sandwich structures could be employed as a skin structure for metallic TPS panels instead of the honeycomb sandwich structure. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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10 pages, 2170 KiB  
Article
Spatial Monitoring of Wafer Map Defect Data Based on 2D Wavelet Spectrum Analysis
by Munwon Lim and Suk Joo Bae
Appl. Sci. 2019, 9(24), 5518; https://doi.org/10.3390/app9245518 - 15 Dec 2019
Cited by 2 | Viewed by 3363
Abstract
Since machine vision systems (MVS) lead to a wide usage of monitoring systems for industrial applications, the research on the statistical process control (SPC) of image data has been promoted as an automated method for early detection and prevention of unusual conditions in [...] Read more.
Since machine vision systems (MVS) lead to a wide usage of monitoring systems for industrial applications, the research on the statistical process control (SPC) of image data has been promoted as an automated method for early detection and prevention of unusual conditions in manufacturing processes. In this paper, we propose a non-parametric SPC approach based on the 2D wavelet spectrum (WS-SPC) to extract the feature that contains the spatial and directional information of each subspace in an image. Using the 2D discrete wavelet transform and spectrum analysis, the representative statistic, the Hurst index, is calculated, and a single matrix space that consists of estimated statistics is reconstructed into a spatial control area for SPC. When a control limit is determined by the density of statistics, real-time monitoring based on WS-SPC is available for time releasing images. In the application, an analysis of wafer bin maps (WBMs) is conducted at a semiconductor company in Korea in order to evaluate the performance of the suggested approach. The results show that the proposed method is effective in terms of its fast computation speed and spectral monitoring. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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12 pages, 4863 KiB  
Article
Failure Prediction for the Tearing of a Pin-Loaded Dual Phase Steel (DP980) Adjusting Guide
by Seokmoo Hong, Jinkyoo Kim and Taehwan Jun
Appl. Sci. 2019, 9(24), 5460; https://doi.org/10.3390/app9245460 - 12 Dec 2019
Cited by 2 | Viewed by 2956
Abstract
Owing to their outstanding strength, in recent years, there has been an increased use of advanced high-strength steel (AHSS) sheets in the automotive sector. Their low formability, however, poses a challenge to forming, and failure prediction requires accurate knowledge of its material behavior [...] Read more.
Owing to their outstanding strength, in recent years, there has been an increased use of advanced high-strength steel (AHSS) sheets in the automotive sector. Their low formability, however, poses a challenge to forming, and failure prediction requires accurate knowledge of its material behavior over a large strain range up to ultimate failure, in order to exploit their full capacity in forming, but also in crash events. For predicting the fracture of an adjusting guide loaded by a pin, first, the force–displacement data are extracted from tensile tests using DP980 specimens of diverse shapes, all of which represent a certain loading mode. Using digital image correlation (DIC), we determine the stress triaxialities corresponding to the diverse loading conditions and establish the triaxiality failure diagram (TFD), which serves as the basis for the generalized incremental stress state-dependent damage model (GISSMO). Then, the damage parameters (necking and failure strains) are determined for each loading mode by reverse engineering-based optimization. Finally, these damage parameters are applied to the adjusting guide, and the numerical results are compared with the experimental data. Comparisons of the external load–displacement curves and the local equivalent strain distributions show that using the damage model with the material parameters obtained in here allows for the accurate prediction of the guide’s failure behavior, and the applicability of GISSMO to complex loading cases. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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13 pages, 11974 KiB  
Article
Steel Surface Defect Diagnostics Using Deep Convolutional Neural Network and Class Activation Map
by Soo Young Lee, Bayu Adhi Tama, Seok Jun Moon and Seungchul Lee
Appl. Sci. 2019, 9(24), 5449; https://doi.org/10.3390/app9245449 - 12 Dec 2019
Cited by 60 | Viewed by 7859
Abstract
Steel defect diagnostics is considerably important for a steel-manufacturing industry as it is strongly related to the product quality and production efficiency. Product quality control suffers from a real-time diagnostic capability since it is less-automatic and is not reliable in detecting steel surface [...] Read more.
Steel defect diagnostics is considerably important for a steel-manufacturing industry as it is strongly related to the product quality and production efficiency. Product quality control suffers from a real-time diagnostic capability since it is less-automatic and is not reliable in detecting steel surface defects. In this study, we propose a relatively new approach for diagnosing steel defects using a deep structured neural network, e.g., convolutional neural network (CNN) with class activation maps. Rather than using a simple deep learning algorithm for the classification task, we extend the CNN diagnostic model for being used to analyze the localized defect regions within the images to support a real-time visual decision-making process. Based on the experimental results, the proposed approach achieves a near-perfect detection performance at 99.44% and 0.99 concerning the accuracy and F-1 score metric, respectively. The results are better than other shallow machine learning algorithms, i.e., support vector machine and logistic regression under the same validation technique. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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9 pages, 2202 KiB  
Article
Development of Zirconium-Based Alloys with Low Elastic Modulus for Dental Implant Materials
by Minsuk Kim, Seongbin An, Chaeeul Huh and Chungseok Kim
Appl. Sci. 2019, 9(24), 5281; https://doi.org/10.3390/app9245281 - 4 Dec 2019
Cited by 15 | Viewed by 4434
Abstract
The stress-shielding effect is a phenomenon in which the mutual coupling between bones and bio-materials of the human body is loosened due to the difference in elastic modulus, and bone absorption occurs due to the difference in density, which causes a shortening of [...] Read more.
The stress-shielding effect is a phenomenon in which the mutual coupling between bones and bio-materials of the human body is loosened due to the difference in elastic modulus, and bone absorption occurs due to the difference in density, which causes a shortening of the life of the material. The purpose of this study is to develop a zirconium-based alloy with low modulus and to prevent the stress-shielding effect. Zr–7Cu–xSn (x = 1, 5, 10, 15 mass%) alloys were prepared by an arc-melting process of pure zirconium, oxygen-free copper, and tin, respectively. The Zr–7Cu–xSn alloy has two phase α-Zr and Zr2Cu intermetallic compounds. Microstructure characterization was analyzed by microscopy and X-ray diffraction. Corrosion tests of zirconium-based alloys were conducted through polarization tests, and zirconium-based alloys had better corrosion characteristics than other metal bio-materials. In general, the elastic modulus value (14–25 GPa) of the zirconium-based alloy is very similar to the elastic modulus value (15–30 GPa) of the human bone. Consequently, the zirconium-based alloy is likely to be used as a bio-material that negates the effect of stress shielding on human bones. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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9 pages, 9721 KiB  
Article
Development of a Reflective 193-nm DUV Microscope System for Defect Inspection of Large Optical Surfaces
by Hong-Seung Kim, Dong-Ho Lee, Sangwon Hyun, Soon Kyu Je, June Gyu Park, Ji Yong Bae, Geon Hee Kim and I Jong Kim
Appl. Sci. 2019, 9(23), 5205; https://doi.org/10.3390/app9235205 - 29 Nov 2019
Cited by 4 | Viewed by 5341
Abstract
We developed a 193-nm deep ultraviolet (DUV) microscope system based on the reflection mode for a precise inspection of various types of defects/cracks on large optical surfaces of the order of one meter in size. Without preprocessing the sample at room temperature and [...] Read more.
We developed a 193-nm deep ultraviolet (DUV) microscope system based on the reflection mode for a precise inspection of various types of defects/cracks on large optical surfaces of the order of one meter in size. Without preprocessing the sample at room temperature and atmospheric pressure, which is commonly necessary for electron microscopy, the reflective 193-nm DUV microscope was used to directly observe optical surface defects in a manner similar to conventional optical microscopes. In addition, the limitations on the selection of materials and thickness of optical samples of transmittive DUV microscopes were overcome. DUV microscope imaging and the analysis on the spatial resolution were verified using a 1D grating structure with a 225-nm line width. This system could be widely applied as an inspection tool because it provides high resolution at the 200-nm scale that is close to the diffraction limit of a 193-nm DUV beam. In the near future, it is expected that our system would be extended to nano/bio imaging as well as the inspection of large optical surfaces. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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14 pages, 7784 KiB  
Article
Effect of Rotating Cylinder on Mixing Performance in a Cylindrical Double-Ribbon Mixer
by V.V.N. Harish, Migyung Cho and Jaesool Shim
Appl. Sci. 2019, 9(23), 5179; https://doi.org/10.3390/app9235179 - 29 Nov 2019
Cited by 7 | Viewed by 5417
Abstract
Uniform mixing is highly essential in the food manufacturing, pharmaceutical, chemical, and cement industries. However, based on the various process requirements, these industries use different mixers to achieve their commercial outputs. Most of these industries rely on sample-based verification of the mixing index, [...] Read more.
Uniform mixing is highly essential in the food manufacturing, pharmaceutical, chemical, and cement industries. However, based on the various process requirements, these industries use different mixers to achieve their commercial outputs. Most of these industries rely on sample-based verification of the mixing index, which may not produce accurate results. Adopting a non-sampling mixing index method is more accurate. In this study, we used the discrete element method (DEM) to simulate the mixing of multiple components contained in a typical commercial whey protein mixture. An effective non-sampling mixing index, the subdomain-based mixing index (SMI), was incorporated to assess the mixing levels. The main motivation for this study was to acquire a high mixing index in the least possible mixing time to boost the manufacturing rate. For this purpose, a half-filled cylindrical double ribbon mixer was simulated, and the SMI outputs are presented for the following four cases: (1) rotating ribbon, (2) rotating cylinder, (3) rotating cylinder with a static ribbon, and (4) rotating cylinder and ribbon. For the given simulation conditions, the SMI values ranged from 0 (segregation condition) to 0.91–0.94 (fully randomly mixed condition) within a time range of 0–60 s. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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11 pages, 5967 KiB  
Article
Flaw Classification Algorithm for Heat Exchanger Tubes Using a Bobbin-Type Magnetic Camera
by Sunbo Sim, Hoyong Lee, Heejong Lee and Jinyi Lee
Appl. Sci. 2019, 9(23), 5000; https://doi.org/10.3390/app9235000 - 20 Nov 2019
Cited by 1 | Viewed by 2765
Abstract
This paper presents an algorithm that estimates the presence, location, shape, and depth of flaws using a bobbin-type magnetic camera consisting of bobbin probes and a bobbin-type integrated giant magnetoresistance (GMR) sensor array (BIGiS). The presence of the flaws is determined by the [...] Read more.
This paper presents an algorithm that estimates the presence, location, shape, and depth of flaws using a bobbin-type magnetic camera consisting of bobbin probes and a bobbin-type integrated giant magnetoresistance (GMR) sensor array (BIGiS). The presence of the flaws is determined by the lobe path of the Lissajous curves obtained from bobbin coil with respect to the applied frequency. The location of the flaw, i.e., whether it is an inner diameter (ID) or outer diameter (OD) flaw, can be determined from the rotational direction of the lobe with respect to the frequency change. The shape of the flaw is then determined from the area of the lobe and the BIGiS image. At this stage, multi-site damage can be determined from the BIGiS image. The effectiveness of the flaw classification algorithm was evaluated using various types of artificial flaws introduced into small-bore tube test specimens made of austenitic stainless steel. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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13 pages, 5088 KiB  
Article
Fabrication of Stretchable Transparent Electrode by Utilizing Self-Induced Vacuum Force
by Chunghwan Lee, Jaesool Shim, Chulho Bae and Kisoo Yoo
Appl. Sci. 2019, 9(23), 4986; https://doi.org/10.3390/app9234986 - 20 Nov 2019
Cited by 1 | Viewed by 2817
Abstract
The key challenge in fabricating a stretchable transparent electrode is the effective transfer of an electric conductor to a stretchable substrate. To this end, we used vacuum force to fully permeate the elastomer substrate into the electric conductor. The vacuum force was self-induced [...] Read more.
The key challenge in fabricating a stretchable transparent electrode is the effective transfer of an electric conductor to a stretchable substrate. To this end, we used vacuum force to fully permeate the elastomer substrate into the electric conductor. The vacuum force was self-induced from the evaporation of the solvent in the electric conductor. Hence, a solvent, having a high evaporation rate, is postulated to exhibit superior fabrication quality. To demonstrate this, three different solvents were tested for preparation of the conductor slurry. In the test, the high-vapor-pressure solvents resulted in the superior quality of the fabricated stretchable electrode. Furthermore, the heating direction was changed during thermal curing to maximize the self-induced vacuum force. The plate-heating curing exhibited better transferring efficiency of the electric conductor because the evaporation of the solvent in the conductor slurry was accelerated faster than that of the thermal curing of the elastomer substrate. Besides the achieved high quality of the electrode, the fabrication cost can be drastically reduced because the extra process required to dry the electric conductor is omitted by simultaneous curing of the electric conductor and the stretchable elastomer substrate. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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14 pages, 4391 KiB  
Article
Measurement Enhancement on Two-Dimensional Temperature Distribution of Methane-Air Premixed Flame Using SMART Algorithm in CT-TDLAS
by Min-Gyu Jeon, Deog-Hee Doh and Yoshihiro Deguchi
Appl. Sci. 2019, 9(22), 4955; https://doi.org/10.3390/app9224955 - 18 Nov 2019
Cited by 10 | Viewed by 3430
Abstract
In this study, the temperature distribution of the Methane-Air premixed flame was measured. In order to enhance the measurement accuracy of the CT-TDLAS (Computed tomography-tunable diode laser absorption spectroscopy), the SMART (simultaneous multiplicative algebraic reconstruction technique) algorithm has been adopted. Further, the SLOS [...] Read more.
In this study, the temperature distribution of the Methane-Air premixed flame was measured. In order to enhance the measurement accuracy of the CT-TDLAS (Computed tomography-tunable diode laser absorption spectroscopy), the SMART (simultaneous multiplicative algebraic reconstruction technique) algorithm has been adopted. Further, the SLOS (summation of line of sight) and the CSLOS (corrective summation of line of sight) methods have been adopted to increase measurement accuracies. It has been verified that the relative error for the temperatures measured by the thermocouples and calculated by the CT-TDLAS was about 10%. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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13 pages, 3541 KiB  
Article
Experiment and Modeling on Macro Fiber Composite Stress-Induced Actuation Function Degradation
by Wei Wang, Zikuo Zhang and Zhichun Yang
Appl. Sci. 2019, 9(21), 4714; https://doi.org/10.3390/app9214714 - 5 Nov 2019
Cited by 5 | Viewed by 2561
Abstract
The effect of stress depolarization will cause actuation function degradation of a piezoelectric actuator, which can eventually trigger function failure of the piezoelectric smart structure system. In the present study, we experimentally demonstrate the degradation process of the actuation function of the Macro [...] Read more.
The effect of stress depolarization will cause actuation function degradation of a piezoelectric actuator, which can eventually trigger function failure of the piezoelectric smart structure system. In the present study, we experimentally demonstrate the degradation process of the actuation function of the Macro Fiber Composite (MFC) piezoelectric actuator. Actuation function degradation data of MFC actuators undergoing cyclic loads with four different stress amplitudes have been measured. Based upon the experimental results, the radial basis function (RBF) neural network learning algorithm was adopted to establish a neural network model, in order to predict the actuation function degenerative degree of the MFC actuator, undergoing arbitrary cyclic load within the concerned stress amplitude range. The maximum relative error between the predicted result and our experimental result is 4%. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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10 pages, 6858 KiB  
Article
Electromagnetic Testing of Rod Cluster Control Assemblies in Pressured-Water Reactor Power Plants
by Minhhuy Le, Sunbo Sim and Jinyi Lee
Appl. Sci. 2019, 9(19), 4013; https://doi.org/10.3390/app9194013 - 25 Sep 2019
Cited by 2 | Viewed by 3516
Abstract
This paper presents an electromagnetic testing system for rod cluster control assemblies used in pressurized-water reactors. The system uses several encircling-type magnetic cameras equivalent to a number of the control rods; each sensor probe composes of an encircling Hall sensor array (EHaS) and [...] Read more.
This paper presents an electromagnetic testing system for rod cluster control assemblies used in pressurized-water reactors. The system uses several encircling-type magnetic cameras equivalent to a number of the control rods; each sensor probe composes of an encircling Hall sensor array (EHaS) and a bobbin coil. The EHaS has 16 Hall sensor elements that measure the electromagnetic field distribution in the radial direction of the control rod induced by the bobbin coil for defects. Experiments are performed on artificial defects on the cladding tube of real control rods to simulate short-circumferential grooves (SCGs), sliding wears (SWs), and circumferential cracks (CCs). The system can inspect the artificial SCGs, SWs, and CCs with depths up to 20%, 30%, and 40% of the cladding tube thickness (0.47 mm), respectively. Furthermore, the shape and depth of the defects could be estimated. The standard deviations of depth estimation are 18%, 5.8%, and 6.0% for CCs, SCGs, and SWs. The SCGs and SWs have a small and similar estimation error, but the CCs have the highest error of estimation, and have a small width of 0.2 mm. Full article
(This article belongs to the Special Issue Selected Papers from the ICMR 2019)
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