Journal of the Korean Society for Precision Engineering

Lightweight Design and Dynamic Verification of Multi-layer Sarrus Deployable Structures for Rotor-sail under Centrifugal Loading: Chan Kim, Sun-Pill Jung, JangGil Kim, Kyu-Jin Cho; J. Korean Soc. Precis. Eng. 2025;42(12):1099-1106.
Published online December 1, 2025; DOI: https://doi.org/10.7736/JKSPE.025.109

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This study presents a vertically deployable rotor-sail structure utilizing multi-layer Sarrus linkages. The structure fully extends during sailing to maximize Magnus lift and compresses to less than half its length for docking. An analytical beam model integrates link thickness, mid part spacing, and centrifugal loading to predict deflection and mass. Parametric comparisons of two-layer, six-layer, and twelve-layer configurations reveal that the twelve-layer design reduces structural mass by 90% while meeting an L/1000 deflection limit. Dynamic simulations using RecurDyn confirm that mid part segmentation decreases damping time and reduces peak stress, thus enhancing deployability and mechanical reliability. The findings offer quantitative design guidance for high-speed rotating deployable structures.

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Comparative Study of CO₂ Diffusion in Multiple Metal-organic Frameworks via Neural Network Potential Molecular Dynamics Simulation: JeongMin Shin, Sangbaek Park, JinHyeok Cha; J. Korean Soc. Precis. Eng. 2025;42(12):1057-1063.
Published online December 1, 2025; DOI: https://doi.org/10.7736/JKSPE.025.00016

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Carbon capture and storage is a vital strategy for mitigating rising atmospheric carbon dioxide, and metal–organic frameworks (MOFs) have gained attention as promising sorbents. Numerous simulations have examined factors governing CO₂ capture in MOFs—such as diffusion in MOF-74 under varying temperatures and process modeling of MOF-5—but most were limited to specific structures or conditions, hindering a systematic understanding of diffusion across diverse MOFs. Conventional computational methods also face constraints: density functional theory mainly provides static energy evaluations, while molecular dynamics relies on fixed force fields with poor transferability and an inability to describe reactive events. To overcome these limitations, this study employs molecular dynamics simulations driven by neural network potentials to evaluate CO₂ diffusivity in 17 types of MOFs. Results reveal significant variation in transport behavior, with zeolitic-imidazolate framework-3 showing the highest diffusivity and MOF-74 the lowest—an approximately 19-fold difference. These findings highlight the capability of neural-network-based molecular dynamics to deliver consistent and quantitative assessments of CO₂ transport in MOFs, providing a reliable framework for the rational design of next-generation capture materials.

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A Numerical Investigation on Heat Transfer Enhancement of a Dual-impeller Heat Exchanger for Electro-optical Tracking System Cooling via System Structural Modification: Sungbin Lee, Manyul Jeon, Hyungpil Park, Donghyeok Park, Hoonhyuk Park, Jongin Bae, Heesung Park; J. Korean Soc. Precis. Eng. 2025;42(10):871-877.
Published online October 1, 2025; DOI: https://doi.org/10.7736/JKSPE.025.071

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This study presents a dual-impeller air-cooled heat exchanger aimed at improving thermal management in electro-optical tracking systems operating under high power density. Two geometric modifications were introduced to enhance flow characteristics and heat transfer performance: the curvature of the center plate and the integration of a pin-fin structure at the outlet. Through numerical simulation, the improved model demonstrated more efficient internal flow compared to the original model, achieved through enhanced inflow characteristics and reduced flow separation. The pin-fin structures induced localized turbulence and recirculation zones, contributing to an increased thermal exchange surface area and longer effective heat transfer time. Consequently, the outlet temperature of the internal system decreased by an average of 1.4°C across various rotational speeds, resulting in a 5.9% increase in heat exchanger efficiency compared to the original model. Overall, this study shows that structural enhancements in heat exchanger design can significantly improve the cooling performance of high-power electronic systems, suggesting practical applicability for advanced thermal management solutions.

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Optimization of Manufacturing Layout Using Deep Reinforcement Learning and Simulation: Ye Ji Choi, Minsung Kim, Byeong Soo Kim; J. Korean Soc. Precis. Eng. 2025;42(3):253-261.
Published online March 1, 2025; DOI: https://doi.org/10.7736/JKSPE.024.137

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Facility Layout Problem (FLP) aims to optimize arrangement of facilities to enhance productivity and minimize costs. Traditional methods face challenges in dealing with the complexity and non-linearity of modern manufacturing environments. This study introduced an approach combining Reinforcement Learning (RL) and simulation to optimize manufacturing line layouts. Deep Q-Network (DQN) learns to reduce unused space, improve path efficiency, and maximize space utilization by optimizing facility placement and material flow. Simulations were used to validate layouts and evaluate performance based on production output, path length, and bending frequency. This RL-based method offers a more adaptable and efficient solution for FLP than traditional techniques, addressing both physical and operational optimization.

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imulation Study on Line-of-sight Stabilization Controller Design for Portable Optical Systems: Jae Woo Jung, Sang Won Jung, Jae Hyun Kim, Seonbin Lim, Youngjin Park, Onemook Kim, Jaehyun Lim, Jae Ho Jin, No-Cheol Park, Jun Young Yoon; J. Korean Soc. Precis. Eng. 2025;42(2):175-183.
Published online February 1, 2025; DOI: https://doi.org/10.7736/JKSPE.024.126

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This paper presents a line-of-sight (LOS) stabilization control method for portable optical systems by analyzing fast steering mirror, image sensor, and gyro sensor system. To compensate for LOS errors caused by hand tremors in portable optical systems, we present the configuration of an image sensor-based LOS stabilization control system and a control strategy considering the phase delay effect caused by low sampling frequency of the image sensor. The phase delay effect of the image sensor caused restricted bandwidth, which limited the stabilization performance. To overcome such limitations, we present disturbance feedforward control using the gyro sensor and controller design method considering characteristics of the gyro sensor. Through overall system modeling, we constructed a control simulation model. The LOS stabilization performance against hand tremor disturbances was analyzed based on the proposed controller design. Simulation results demonstrated that integrating a gyro sensor-based disturbance feedforward control with the image sensor-based LOS stabilization control significantly enhanced the stabilization performance.

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Development of Simulation Model for a 40 kW Electric Tractor based on Dual Motors and Single Planetary Gear: Gang Hyun Kim, Kyeong Dae Kim, Si Yeong Lee, Dae Cheol Kim, Won Gun Kim; J. Korean Soc. Precis. Eng. 2024;41(12):939-948.
Published online December 1, 2024; DOI: https://doi.org/10.7736/JKSPE.024.084

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The purpose of this paper was to develop a simulation model for a 40 kW electric tractor using a powertrain based on dual motors and a planetary gear. To select motor capacity and reduction gear ratio based on the power flow for agricultural work, load data for various gear conditions were acquired and analyzed using a 42 kW engine tractor of similar capacity. Modeling was conducted using MATLAB/Simulink/Simscape. Load data acquired through actual field tests were applied as load conditions for the simulation. Simulation results confirmed that the power was transmitted through the planetary gear as the clutch and brake operated according to the work mode. The developed simulation model is expected to be used for electric tractor development.

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Optical Performance Using the Surface Form Error Modeling based on A Monte-Carlos Simulation of An Optical Window: Kwang-Woo Park, Ji-Hun Bae, Chi-Yeon Kim; J. Korean Soc. Precis. Eng. 2024;41(9):725-729.
Published online September 1, 2024; DOI: https://doi.org/10.7736/JKSPE.024.076

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As system performance continues to improve at higher resolutions, it becomes increasingly important to establish standards for imaging degradation caused by optical windows. In this study, random surface shapes were simulated on large area optical windows with peak-to-valley (P-v) values of 0.25, 0.5, and 1.0 λ. Modulation Transfer Function (MTF) values were derived for 1,000 cases per P-v value using Monte-Carlo simulations. The specifications achieved a surface accuracy of 0.5 λ and a parallelism of 0.01 mm. MTF measurements showed that the system MTF was 13.5% prior to the installation of the optical window, and 13.1% after installation. This indicates a degradation rate of approximately 3%.

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Prediction of Image Quality according to Environmental Changes in a Reflective Aerospace Optical System: Kisoo Kim, Ji-Hun Bae, Jongbok Park; J. Korean Soc. Precis. Eng. 2024;41(7):581-587.
Published online July 1, 2024; DOI: https://doi.org/10.7736/JKSPE.024.051

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The use of reflective optical systems is essential to acquiring high-resolution image quality in aerospace applications that observe distant objects. The geometric shapes of large-aperture reflective optical systems can be deformed depending on various operating and space environments, which deformation consequently affects optical performance. In this study, we predict the image quality of a reflective aerospace optical system according to various environmental changes. In particular, the shape deformation due to vibration and heat generated from the launch vehicle was mainly observed, and the effect on gravity was also considered. The variations of image quality, such as Modulation Transfer Function (MTF) and wave-front error (WFE), were also observed by importing the deformed shapes into the optical simulation tool. This study is intended to provide approaches to reduce the cost and lead time to develop aerospace optical systems.

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A Study on Numerical Analysis for Determination of Glass Molding Process Conditions for Glass Lenses: Jaehun Choi, Sajan Tamang, Heesung Park; J. Korean Soc. Precis. Eng. 2024;41(3):207-214.
Published online March 1, 2024; DOI: https://doi.org/10.7736/JKSPE.023.136

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The Glass Molding Process (GMP) produces large quantities of glass optical parts and provides the advantages of high molding accuracy, short production cycle, low cost, and little pollution. Developments in different sectors, such as cameras and telescopes, are prompting studies on the design of aspherical optical components. Modeling heat transfer and deformation at high temperatures are crucial aspects of studying glass because its properties are significantly influenced by temperature-induced phase changes. In this study, temperature changes and geometric deviations of lenses were studied with respect to heating, pressing, and cooling times and the heat capacity of the heater used. A 3D model was designed for the heating, pressing, and cooling steps, and heat transfer was subjected to numerical analysis considering the specific heat of glass and the temperature dependence of thermal conductivity. Lens molding temperature conditions were then analyzed with the heat capacity of the lens molding heating system. Lens molding conditions were derived by analyzing lens temperatures with respect to heating and cooling capacities at each process step.

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Precision glass aspherical lens manufacturing by compression molding: a review
Xiaohua Liu, Jian Zhou, Bo Tao, Yang Shu, Zexin Feng, Shih-Chi Chen, Yingying Zhang, Allen Y. Yi
Light: Advanced Manufacturing.2026; 7: 1. CrossRef
A Study on Temperature and Stress Distribution in a Lens under Multi-Stage Cooling Conditions in Progressive Glass Molding Processes
Ji Hyun Hong, Jeong Taek Hong, Dong Yean Jung, Young Bok Kim, Keun Park, Chang Yong Park
Journal of the Korean Society for Precision Engineering.2025; 42(2): 157. CrossRef

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Implementation and Verification of Fresnel Zone Plate Patterns Designed by Optimization of Surface Phase: Huy Vu, Joohyung Lee; J. Korean Soc. Precis. Eng. 2024;41(1):79-84.
Published online January 1, 2024; DOI: https://doi.org/10.7736/JKSPE.023.124

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In this study, we present a numerical simulation approach for designing Fresnel zone plate (FZP) patterns. By optimizing surface phase parameters using desired merit functions in ray-tracing software, the obtained surface phase was converted into an FZP pattern through a 5-step procedure. A comparison between our numerical simulation approach and the traditional analytical method showed a negligible zone size difference of 0.606 nm and nearly absolute agreement of 17.549 μm in focal spot size. The FZP pattern was experimentally verified by an expected focal spot size of 18.55 μm. Our approach demonstrated design flexibility and has potential applications in simulating various functionalities in FZP patterns and refractive-diffractive hybrid lenses to address specific optical challenges. The surface phase can be freely modified based on optimization objectives that cannot be achieved using the analytical approach, ensuring high-precision design for accurate extraction.

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Mechanistic evaluations of radial fiber tip for circumferential laser ablation
Minh Duc Ta, Jiho Lee, Seonho Jung, Van Gia Truong, Hyun Wook Kang
Optics & Laser Technology.2025; 192: 113660. CrossRef
Quantitative investigations on light emission profiles for interstitial laser treatment
Minh Duc Ta, Yeongeun Kim, Hwarang Shin, Van Gia Truong, Hyun Wook Kang
Biomedical Optics Express.2024; 15(12): 6877. CrossRef

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Reflective Optical Systems for Aerospace Applications: Kisoo Kim, Ji-Hun Bae, Jongbok Park; J. Korean Soc. Precis. Eng. 2023;40(11):899-906.
Published online November 1, 2023; DOI: https://doi.org/10.7736/JKSPE.023.080

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The utilization of aerospace technology is growing to meet various requirements of climate change sensing, communications, and the military. Large aperture and precise reflective optical systems such as mirrors are needed to acquire high-quality data, and the requirements of lightness, low cost, and low deformation should also be met to operate in the space environment. In this review, we highlight the recent progress of reflective optical systems for aerospace applications. In particular, optical systems for artificial satellites and homing optics are mainly introduced, and optical and mechanical simulations are discussed according to operating environments. We also discuss various reflective optic designs, materials, and operating principles for aerospace applications, such as a homing head and optical payload. We hope that this review provides approaches for developing surveillance systems, exploring space, and addressing the climate crisis.

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Prediction of Image Quality according to Environmental Changes in a Reflective Aerospace Optical System
Kisoo Kim, Ji-Hun Bae, Jongbok Park
Journal of the Korean Society for Precision Engineering.2024; 41(7): 581. CrossRef

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A Study on Structural Integrity Improvement of Cargo Drone through FE Simulation and Topology Optimization: 성종섭 , 시하영 , 강범수 , 구태완; J. Korean Soc. Precis. Eng. 2023;40(9):685-693.
Published online September 1, 2023; DOI: https://doi.org/10.7736/JKSPE.023.065

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This study deals with the structural integrity of a co-axial octocopter cargo drone. Most unstable states in progress of various flight missions of the cargo drone are considered to be derived from take-off and landing operations. In order to evaluate the structural integrity of these states, three-dimensional FE (finite element) simulation using whole frame assembled with structural members and components is performed, and then the effective stress level and deflection degree are investigated. Also, topology optimization is adopted to improve the locally concentrated stress and large deflection around front and rear sections of the motor-support side member. From topology optimization, it is ensured that the shape and location of plate support have to be modified for improving the stress level and the deflection degree. Based on the optimized and modified feature, FE simulation is re-performed. Consequently, it is confirmed that the effective stress and the deflection are reduced to about 26.67% and 19.15% around the side member, respectively.

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Utilization of topology optimization and generative design for drone frame optimization
Michał Kowalik, Michał Śliwiński, Mateusz Papis
Aircraft Engineering and Aerospace Technology.2025; 97(7): 813. CrossRef

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A Study on the Characteristics of the Retainer applied to Taped Roller Bearings under High Speed Operating Condition: Kang Seok Kim, Kyoung Ku Lee, Deug Woo Lee; J. Korean Soc. Precis. Eng. 2023;40(7):563-570.
Published online July 1, 2023; DOI: https://doi.org/10.7736/JKSPE.023.007

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Factors such as weight reduction and improved fuel efficiency of vehicles interfere with the efficiency of roller bearings in automobiles under harsh conditions. In particular, studies are ongoing to increase the load capacity and rigidity under highspeed conditions. The development of tapered roller bearings that can be used under high-speed conditions is accelerating. In the case of high-speed bearings, factors such as centrifugal force, gyroscopic moment, and slippage have a greater influence on the performance of the bearing, unlike the traditional operating mechanisms. The resulting lubrication characteristics have a profound impact on the failure mode of the bearing. In particular, unlike traditional roller bearings, system failure due to damage to the retainer frequently occurs, suggesting the need for prompt investigation. In this study, the rotational characteristics and strength of three models, a steel cage and two plastic cages for tapered roller bearings with the same internal structure, were examined. A comparative analysis of retainers with different shapes and materials can reveal the factors contributing to optimal performance under high-speed operating conditions and the optimal design of bearings.

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Additive Manufacturing for Rapid and Precise Pattern Formation in Shoes Mold: Seok-Rok Lee, Eun-Ah Kim, Ye-Rim Kim, Dalgyun Kim, Sunjoo Kim, Soonho Won, Hak-Sung Lee; J. Korean Soc. Precis. Eng. 2023;40(3):211-216.
Published online March 1, 2023; DOI: https://doi.org/10.7736/JKSPE.023.005

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In this study, the design for additive manufacturing of shoe molds with complex and precise patterns was performed to achieve rapid prototyping. Low alloy steels such as AISI4340 and SAE1524 were selected to make shoe molds to apply to the conventional chemical etching process. A lattice-oriented design and optimization of toolpath was tested to reduce the processing time. A reduction of 60% in processing time and pattern precision of 0.3 ㎜ was been achieved. Moreover, to improve the reliability of pattern formation, single-layer image analysis with computer vision and machine learning was developed and non-destructive analysis by X-ray CT was been performed. It was found that the quality of shoe molds can be decreased with a single defective layer.

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Optimal Design of Microwave Shielding Door by Using of Design of Experiments: Ka Hee Lee, Kwang Kim; J. Korean Soc. Precis. Eng. 2023;40(1):13-19.
Published online January 1, 2023; DOI: https://doi.org/10.7736/JKSPE.022.104

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In the heating and drying system using microwaves, an optimal design method was presented to effectively shield microwaves leakage between the door and the cylindrical applicator. In order to protect the human body from leaking microwaves, it is necessary to keep the intensity of microwaves below 5 mW/cm². The door part adopts a choke structure and includes a number of design factors, such as, fin shape, slit shape, and a gap between the applicator and the door. The geometry was optimized by design of experiments, applying full factorial design and response surface method in a 4-factor, 2-level design. The results obtained by ANSYS HFSS analysis were applied to the intensity of microwave leakage according to the change of the design factors. The shape of the choke structure was optimized using Minitab, a statistical program. The microwave heating and drying system was manufactured based on optimal design value and the leakage of microwaves between the door and the applicator was measured. We confirmed that the experimental values were consistent with the simulation values.