Journal of the Korean Society for Precision Engineering

Tape-casting Process Electrochemical Characteristic Test for Fabrication of LST-GDC for Anode Supported SOFCs: Min Ji Kim, Chunghyun Kim, Young-Beom Kim; J. Korean Soc. Precis. Eng. 2025;42(11):937-942.
Published online November 1, 2025; DOI: https://doi.org/10.7736/JKSPE.025.073

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In this study, we developed a composite anode support composed of La-doped SrTiO₃ (LST) and Gd-doped CeO₂ (GDC) using a tape casting process for solid oxide fuel cells (SOFCs). By adjusting the pore former content in the slurry, we constructed a bilayered structure consisting of a porous anode support layer (ASL) and a dense anode functional layer (AFL) with the same material composition. The number of tape-cast sheets was controlled to tailor the overall thickness, and lamination followed by co-sintering at 1250^oC resulted in a mechanically robust bilayer. We characterized the microstructural evolution concerning sintering temperature and pore former content using SEM, while XRD confirmed the phase stability of LST and GDC. The measured electrical conductivity at 750^oC ensured sufficient electron transport. To enhance interfacial adhesion and suppress secondary phase formation, we introduced a GDC buffer layer and a pre-sintering treatment prior to electrolyte deposition. A full cell with a YSZ electrolyte and LSCF cathode achieved a stable open circuit voltage of approximately 0.7 V and demonstrated continuous operation at 750^oC. These findings highlight the suitability of LST-GDC composite anodes as thermochemically stable supports, potentially enabling direct hydrocarbon utilization in intermediate-temperature SOFCs.

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Detection Method for Island Regions in 3D Printing: A CPU-based Approach: Young Seok Kang, Yeun Seop Kim, Seung Chae Na, Sang Jo Han; J. Korean Soc. Precis. Eng. 2025;42(1):89-96.
Published online January 1, 2025; DOI: https://doi.org/10.7736/JKSPE.024.124

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Additive manufacturing, a key enabler of Industry 4.0, is revolutionizing the automatic landscape in manufacturing. The primary challenge in manufacturing innovation centers on the implementation of smart factories characterized by unmanned production facilities and automated management systems. To overcome this challenge, the adoption of 3D printing technologies, which offer significant advantages in standardizing production processes, is crucial. However, a major obstacle in complete automation of additive manufacturing is an inadequate placement of support structures at critical locations, which remains the leading cause of print failures. This study proposed a novel algorithm for accurate detection of island regions known to be critical areas requiring support structures. The algorithm can compare loops on two consecutive layers derived from STL files. In contrast to conventional GPU-based image comparison methods, our proposed CPU-based algorithm enables high-precision detection independent of image resolution. Experimental results demonstrated the algorithm's efficacy in enhancing the reliability of 3D printing processes and optimizing automated workflows. This research contributes to the advancement of smart manufacturing by addressing a critical challenge in the automation of additive manufacturing processes.

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Laser Pointing Control System based on Deep Reinforcement Learning Algorithm: Geemin Lee, Youngsu Park, Wonho Choi, Dae Gyu Choi, Chikyung Ahn, Yongeun Yoon; J. Korean Soc. Precis. Eng. 2024;41(12):949-955.
Published online December 1, 2024; DOI: https://doi.org/10.7736/JKSPE.024.088

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In the field of optical engineering, the laser position control system has important role in many applications, such as measurement, communication, fabrication. Traditional methods to solve laser position control system often face the problems of insufficient generalization, such as configuration or singular solution. In this study we proposed a novel model- free reinforcement learning approach based Proximal Policy Optimization (PPO) for laser position control system. To control the position of laser, we develop an efficient representation of environmental inputs and outputs. Position error of Position Sensing Detector (PSD), and three kinds of distance parameters are applied our environmental parameters. To overcome the challenges associated with training in real worlds, we developed training environment in simulation. The simulation to evaluate performance of our approach, we perform several times of experiments in both simulated and real world system.

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Performance Analysis according to Microstructure of Anode Function Layer based on Porous Metal Substrate for Solid Oxide Fuel Cells: Jisung Yoon, Young-Beom Kim; J. Korean Soc. Precis. Eng. 2024;41(10):777-781.
Published online October 1, 2024; DOI: https://doi.org/10.7736/JKSPE.024.002

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In this study, to improve the performance of a solid oxide fuel cell based on a porous metal support, a fuel cell using a multi-layered anode functional layer was fabricated and electrochemical performance analysis was performed. Surface and cross-sectional microstructures according to particle size control were confirmed through FE-SEM. The pore size of the multi-layer anode functional layer was gradually reduced compared to that of a single-structure anode functional layer. As a result, it was confirmed that the surface roughness was lower than that of the single structure. This led to a reduction in polarization resistance through smooth transmission of gas generated from the electrode. As a result, it was confirmed that electrochemical performance was improved by more than 1.25 times in fuel cells using a multi-layered anode functional layer compared to that with a single structure.

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Press Forming/Drawing Molding in the Radiator Support Mold Process of 440 MPa High Strength Steel Sheets: Dong-Hwan Park, Tae-Gil Lee, Hyuk-Hong Kwon; J. Korean Soc. Precis. Eng. 2024;41(1):71-78.
Published online January 1, 2024; DOI: https://doi.org/10.7736/JKSPE.023.110

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This study aimed to develop automotive radiator support parts by applying the press forming/drawing mold technology of 440 MPa high-tensile steel sheets. It is intended to develop a shape structure that does not generate shape and positional accuracy, deformation, wrinkles, or cracks by maintaining strong contact surface pressure on both sides of the blank material and freezing elastic recovery stress. Therefore, quality improvement and high productivity were secured by applying the forming/drawing method of high-strength steel sheets to the radiator support parts.

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Structural Integrity Improvement on Engine-Generator Support Structure for Hybrid Drone through Finite Element Analysis and Experimental Verification: Ki Beom Kim, Jae Nam Kim, Hyun Seock Lee, Hyun Cheol Kim, Tae-Wan Ku, Beom-Soo Kang; J. Korean Soc. Precis. Eng. 2022;39(12):913-921.
Published online December 1, 2022; DOI: https://doi.org/10.7736/JKSPE.022.076

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In this study, the structural integrity of an engine-generator support structure of hybrid drone is verified through finite element (FE) analysis and experimental investigation. From preliminary experiments, critical failures in four columns of the support structure were observed. Due to the repeated cyclic loads induced by the engine-generator operation, the results of the FE simulation pointed out that fatigue failure is the main cause. To improve the structural integrity, the geometric shape and the material of the structural members are modified and changed, and the safety factor is also reviewed using static structural analysis. The possibility of critical resonance is evaluated through FEM-associated modal analysis and a series of vibration tests. As result, it is confirmed that the re-designed support structure was structurally improved with enough safety margin through FE analysis and experimental investigation, and fatigue life by comparing the predicted value and S-N curve of the material used to the support structure was improved.

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Structural Design and Analysis of a Quadcopter Type CanSat for Diverse Launch Conditions
Yongseon Lee, Hyeongyu Lim, Hyeonchang Yang, Changbeom Choi, Jinsung Rho
Journal of the Korean Society for Precision Engineering.2026; 43(1): 29. CrossRef
A Study on Structural Integrity Improvement of Cargo Drone through FE Simulation and Topology Optimization
Jong Seop Seong, Ha-Young Shi, Beom-Soo Kang, Tae-Wan Ku
Journal of the Korean Society for Precision Engineering.2023; 40(9): 685. CrossRef

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Optimal Design for Strength Improvement of Support Bracket for Sanding Device of Railway Vehicle Using Topology Optimization: Yonho Cho, Woohyuck Yoon; J. Korean Soc. Precis. Eng. 2020;37(4):263-270.
Published online April 1, 2020; DOI: https://doi.org/10.7736/JKSPE.019.114

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The sanding device support bracket is part of the axle box and is one of the railway vehicles parts that must withstand extremely harsh environments. Conventional welded structure type brackets were cracked at welds during operation, requiring design changes. To minimize harsh environments and manufacturing errors, this review was conducted from the design stage, and design changes were made through several trial and error. In this paper, the optimal design was derived by performing topology optimization on the model designed and manufactured through trial and error and applied to the actual vehicle. The comparison of the existing model with the empirically designed model confirmed the improvement of the optimal design using the topology optimization. The optimized design was verified by the analysis and the vibration test of IEC 61373 was satisfied. The test parts based on the optimal design were applied to the actual vehicle and the performance was verified. In the optimum design process, the shape and material as well as the weight analysis were performed and finally the brackets were designed to be light in weight and improved in strength.

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Experimental study on the influencing factors of particles jetting behavior in train sanding adhesion enhancement
Z.H. Yue, S.Y. Zhang, H.H. Ding, X.X. Song, Q. Lin, J. Guo, W.J. Wang
Powder Technology.2024; 448: 120302. CrossRef
Study on the Optimal Design of Column Rib Structure of Horizontal Machine Tool Using Topology Optimization Technique
Ji-Sang Hwang, Sung-Jae Kim, Chul-Hoon Sung
Journal of the Korean Society of Manufacturing Technology Engineers.2023; 32(1): 1. CrossRef
Optimal Design and Experimental Validation of the Rib Structure of a Manufacturing Machine Bed Using Topology Optimization
Ji-Sang Hwang, Sung-Jae Kim, Jeong-Hyun Yoon, Chul-Hoon Sung
Journal of the Korean Society of Manufacturing Technology Engineers.2023; 32(6): 374. CrossRef

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Development of the Algorithm of Locomotion Modes Decision based on RBF-SVM for Hip Gait Assist Robot: Dong Bin Shin, Seung Chan Lee, Seung Hoon Hwang, In Hyuk Baek, Joon Kyu No, Soon Woong Hwang, Chang Soo Han; J. Korean Soc. Precis. Eng. 2020;37(3):187-194.
Published online March 1, 2020; DOI: https://doi.org/10.7736/JKSPE.019.117

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The purpose of this study was to suggest the method for automated locomotion modes (Level Walking, Stair Ascent, Stair Descent) detection based on the Radial Basis Function Support Vector Machine (RBF-SVM) for the hip gait assist robot. The universal hip gait assist robot had a limit in detection of the walking intention of users because of the limited sensors’ quantity. Through the offline training, using MATLAB, we trained the collected gait data of users wearing the hip gait assist robot and obtained the parameter of the RBF-SVM model. In the online test, using LabVIEW, we developed the algorithm for the locomotion modes decision of individuals using the optimized parameter of the RBF-SVM. Finally, we executed the gait test for three terrains through the walking environment’s test platform. As a result, the locomotion modes decision rate for three terrains was 98.5%, 99%, and 98% respectively. And the decision delay time of algorithm was 0.03 s, 0.03 s, and 0.06 s respectively.

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A fuzzy convolutional attention-based GRU network for human activity recognition
Ghazaleh Khodabandelou, Huiseok Moon, Yacine Amirat, Samer Mohammed
Engineering Applications of Artificial Intelligence.2023; 118: 105702. CrossRef
Locomotion Mode Recognition Algorithm Based on Gaussian Mixture Model Using IMU Sensors
Dongbin Shin, Seungchan Lee, Seunghoon Hwang
Sensors.2021; 21(8): 2785. CrossRef

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Back Support Exoskeleton Robot for Soldiers: Military Applicability Analysis: Yeo Hun Yoon; J. Korean Soc. Precis. Eng. 2018;35(10):925-931.
Published online October 1, 2018; DOI: https://doi.org/10.7736/KSPE.2018.35.10.925

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In this paper, we examine the exoskeleton robot which can support the muscular strength of the soldiers handling the front load and its applicability in the military field. In fact, in the questionnaire survey on the military applicability of exoskeleton robots, many soldiers reported that they felt immensely fatigued due to the heavy load on their back during the operation. Most of the exoskeleton robots in the military have been developed to reduce fatigue during the mobility and movement of soldiers. Research on the exoskeleton robots to support the waist has been carried out with emphasis on its role in assisting performance of repetitive work in the industrial field or the medical field. To examine the studies on conventional back support exoskeleton robots and to find out the functions required to apply a back-support exoskeleton robot to soldiers, we have classified the existing back support exoskeleton robots into power type, supported body, waterproof grades, and others based on weight, purpose, working time, etc. Apparently, the shape of the exoskeleton robot suitable for application in the military field and the required performance is presented in the present work.

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Muscle Strength Assistance of a Shape Memory Alloy Exoskeleton During Lifting and Lowering Tasks
Kwang Hee Lee, Mi Yu, Young Min Kim, Lae Hoon Jeong, Tae Kyu Kwon
International Journal of Precision Engineering and Manufacturing.2025; 26(4): 1013. CrossRef
Design of Exo-Suit for Shoulder Muscle Strength Support
Kwang-Woo Jeon, TaeHwan Kim, SeungWoo Kim, JungJun Kim, Hyun-Joon Chung
Journal of Korea Robotics Society.2023; 18(1): 110. CrossRef
Mapping of Human Contact Areas for Application Field of Wearable Robots
Ran-i Eom, Yejin Lee
International Journal of Costume and Fashion.2020; 20(2): 11. CrossRef

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Feature-Based Analysis for Fault Diagnosis of Gas Turbine using Machine Learning and Genetic Algorithms: Byung Hyun Ahn, Hyeon Tak Yu, Byeong Keun Choi; J. Korean Soc. Precis. Eng. 2018;35(2):163-167.
Published online February 1, 2018; DOI: https://doi.org/10.7736/KSPE.2018.35.2.163

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Fault diagnosis and condition monitoring of rotating machines are important for the maintenance of the gas turbine system. In this paper, the Lab-scale rotor test device is simulated by a gas turbine, and faults are simulated such as Rubbing, Misalignment and Unbalance, which occurred from a gas turbine critical fault mode. In addition, blade rubbing is one of the gas turbine main faults, as well as a hard to detect fault early using FFT analysis and orbit plot. However, through a feature based analysis, the fault classification is evaluated according to several critical faults. Therefore, the possibility of a feature analysis of the vibration signal is confirmed for rotating machinery. The fault simulator for an acquired vibration signal is a rotor-kit based test rig with a simulated blade rubbing fault mode test device. Feature selection based on GA (Genetic Algorithms) one of the feature selection algorithm is selected. Then, through the Support Vector Machine, one of machine learning, feature classification is evaluated. The results of the performance of the GA compared with the PCA (Principle Component Analysis) for reducing dimension are presented. Therefore, through data learning, several main faults of the gas turbine are evaluated by fault classification using the SVM (Support Vector Machine).

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A Study on Machine Learning-Based Feature Classification for the Early Diagnosis of Blade Rubbing
Dong-hee Park, Byeong-keun Choi
Sensors.2024; 24(18): 6013. CrossRef
Feature selection and feature learning in machine learning applications for gas turbines: A review
Jiarui Xie, Manuel Sage, Yaoyao Fiona Zhao
Engineering Applications of Artificial Intelligence.2023; 117: 105591. CrossRef
Simultaneous Fault Diagnostics for Three-Shaft Industrial Gas Turbine
Waleligne Molla Salilew, Syed Ihtsham Gilani, Tamiru Alemu Lemma, Amare Desalegn Fentaye, Konstantinos G. Kyprianidis
Machines.2023; 11(8): 832. CrossRef
A Machine Learning-Based Signal Analytics Framework for Diagnosing the Anomalies of Centrifugal Pumps
Kang Whi Kim, Jihoon Kang, Seung Hwan Park
Journal of the Korean Society for Precision Engineering.2021; 38(4): 269. CrossRef
Performance Improvement of Feature-Based Fault Classification for Rotor System
Won-Kyu Lee, Deok-Yeong Cheong, Dong-Hee Park, Byeong-Keun Choi
International Journal of Precision Engineering and Manufacturing.2020; 21(6): 1065. CrossRef

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Design and Evaluation of the Control Performance of a Compliant Arm Support: Sang-Hun Kim, Useok Jeong, Daegeun Park, Inwook Koo, Kyu-Jin Cho; J. Korean Soc. Precis. Eng. 2017;34(2):115-123.
Published online February 1, 2017; DOI: https://doi.org/10.7736/KSPE.2017.34.2.115

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This paper presents the design and the control performance of a novel dynamic compliant-arm support with parallel elastic actuators that was developed to assist with the daily living activities of those whose arms are compromised by muscular disease or the aging process. The parallel elastic-arm support consists of a compliant mechanism with combined passive and active components for human interaction and to reach the user’s desired positions. The achievement of these tasks requires impedance control, which can change the virtual stiffness, damping coefficients, and equilibrium points of the system; however, the desired-position tracking by the impedance control is limited when the end-effector weight varies according to the equipping of diverse objects. A prompt algorithm regarding weight calibration and friction compensation is adopted to overcome this problem. A result comparison shows that, by accurately assessing the desired workspace, the proposed algorithm is more effective for the accomplishment of the desired activities.

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Calibration Algorithm of a Spring Static Balancer
Chang-Hyun Cho, Mun-Taek Choi
International Journal of Precision Engineering and Manufacturing.2018; 19(10): 1477. CrossRef

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