Journal of the Korean Society for Precision Engineering

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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Development of an International Standards-based Energy Consumption Evaluation System for Enhancing Machine Tool Energy Efficiency: Gyungho Khim, Jeong Seok Oh, Sungcheul Lee, Jaehak Lee; J. Korean Soc. Precis. Eng. 2025;42(5):391-398.
Published online May 1, 2025; DOI: https://doi.org/10.7736/JKSPE.025.033

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As the global manufacturing industry moves toward carbon neutrality, improving energy efficiency of machine tools has become essential. Although machine tools contribute significantly to industrial energy consumption, systematic methods for evaluating their energy consumption remain insufficient. To address this issue, this study developed an energy consumption evaluation system based on ISO 14955, the international standard for machine tool energy efficiency. The proposed system enabled a detailed analysis of energy usage patterns in different operating states, identifying key areas for energy reduction. The developed system could measure energy consumption of individual machine tool components in various operating states using power meters and automatically generates reports. This allows users to identify which components and operating states consume the most energy. We tested and validated this system on three different machine tools and analyzed strategies for reducing energy consumption. The developed evaluation system can help machine tool manufacturers integrate it into their equipment, develop energy-efficient technologies, and contribute to sustainable manufacturing.

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Recent Advances in CNC Technology: Toward Autonomous and Sustainable Manufacturing
Jong-Min Lim, Wontaek Song, Joon-Soo Lee, Ji-Myeong Park, Hee-Min Shin, In-Wook Oh, Soon-Hong Hwang, Seungmin Jeong, Sangwon Kang, Chan-Young Lee, Byung-Kwon Min
International Journal of Precision Engineering and Manufacturing.2025; 26(9): 2311. CrossRef

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Development of Distributed Hybrid Type Heating System Having Heat-Pump Technic for Agriculture: Ju Min Lee, Goo Jo Kim, Eun Gi Ahn; J. Korean Soc. Precis. Eng. 2022;39(12):905-911.
Published online December 1, 2022; DOI: https://doi.org/10.7736/JKSPE.022.075

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Development of Advertising Accessory with Light Guide for Mobile Devices: Kihyun Kim, Je-Heon Han; J. Korean Soc. Precis. Eng. 2019;36(5):485-491.
Published online May 1, 2019; DOI: https://doi.org/10.7736/KSPE.2019.36.5.485

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This paper presents a development process of an advertising accessory including a light guide to be applied to mobile devices. At first, this research is to design an optical part as a light guide to transmit the light more than 10% of the LED light from mobile devices. Secondly, it presents the mechanical design of the part to be applicable to size changes of mobile devices and to enduring external forces. By using ANSYS and OPTISWORKS, a preliminary design including to tune the applied material properties is performed to prevent from the failure of the component, to maintain the proper pressure for holding mobile devices with different thickness, and to obtain enough optical transmission efficiency. In addition, this paper introduces a manufacturing process for the advertising accessory with a chemical and mechanical polishing. In order to measure the performance of the manufactured accessory, here, measurement devices such as measuring the pressing force, luminance, and illuminance are also designed and fabricated. Several modifications are made for the purpose of improving the measured performance.

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Design and Testing of a Compact Tattooing Mechanism for Capsule Endoscope: Seonggun Joe, Dongkyu Lee, Byungjeon Kang, Jong-Oh Park, Byungkyu Kim; J. Korean Soc. Precis. Eng. 2019;36(5):449-454.
Published online May 1, 2019; DOI: https://doi.org/10.7736/KSPE.2019.36.5.449

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The process of tattooing to mark the position of lesions in the colon is one of important functions of the conventional endoscope. However, commercial capsule endoscope (CE) devices cannot perform the tattooing procedure because they cannot accommodate the size of the tattooing device. In this paper, we propose a compact tattooing mechanism design which can be accommodated inside the CE. Two conical springs, two triggering modules and a needle that can be installed inside a volume of 840 mm3 are employed to perform the needle insertion/withdrawal and inject the ink. A triggering module to deploy the conical springs is designed to be activated by heating a Ni-Cr wire and melting Wood’s metal. In this study, the activation time of the triggering module is investigated based on a Wood’s metal heating simulation. In order to determine the proper conical springs to ensure the activation of the tattooing mechanism, the elastic force correlation between two conical springs is studied. Then, the components of the proposed tattooing mechanism are fabricated and assembled, and an ex-vivo test is performed. Conclusively, the proposed tattooing mechanism implements the correct needle stroke and the proper ink injection into the submucosal layer of a porcine colon.

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Robotic Localization Based on Planar Cable Robot and Hall Sensor Array Applied to Magnetic Capsule Endoscope
Min-Cheol Kim, Eui-Sun Kim, Jong-Oh Park, Eunpyo Choi, Chang-Sei Kim
Sensors.2020; 20(20): 5728. CrossRef

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Investigation of Penetration Depth and Efficiency of Applied Heat Flux in a Directed Energy Deposition Process with Feeding of Ti-6Al-4V Wires: Bih Lii Chua, Ho Jin Lee, Dong Gyu Ahn, Jae Gu Kim; J. Korean Soc. Precis. Eng. 2018;35(2):211-217.
Published online February 1, 2018; DOI: https://doi.org/10.7736/KSPE.2018.35.2.211

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Wire feeding type directed energy deposition (DED) process is able to produce metal parts with high density at high deposition rate. However, the parts are subjected to high residual stresses and distortion due to its large heat input. In order to simulate the thermal stress, a proper heat input parameter is required. The goal of this paper is to investigate the efficiency and penetration depth of the applied heat flux in the DED process. The estimation method for the penetration depth and efficiency of applied heat flux is proposed using the thermal finite element analyses (FEAs). A finite element model is developed according to the cross sectional profile of the actual deposited beads. A top-hat volumetric heat flux is adopted to simulate the transient thermal phenomenon of the laser based wire feeding type DED process. The estimated heat affected zone (HAZ) from the FEAs is compared with the experimental results in order to estimate the proper efficiency and penetration depth of the laser beam for each condition of DED process.

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Materials & Design.2025; 252: 113609. CrossRef
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Journal of the Korean Society of Manufacturing Process Engineers.2021; 20(10): 27. CrossRef
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Journal of the Korean Society of Manufacturing Process Engineers.2020; 19(8): 56. CrossRef
Estimation Method of Interpass Time for the Control of Temperature during a Directed Energy Deposition Process of a Ti–6Al–4V Planar Layer
Bih-Lii Chua, Dong-Gyu Ahn
Materials.2020; 13(21): 4935. CrossRef
A Study on Activation Algorithm of Finite Elements for Three-Dimensional Transient Heat Transfer Analysis of Directed Energy Deposition Process
Bih-Lii Chua, Ho-Jin Lee, Dong-Gyu Ahn, Yeqing Wang
International Journal of Precision Engineering and Manufacturing.2019; 20(5): 863. CrossRef
Influences of deposition strategies on thermo-mechanical characteristics of a multilayer part deposited by a wire feeding type DED process
Bih Lii Chua, Dong-Gyu Ahn, Jae-Gu Kim
Journal of Mechanical Science and Technology.2019; 33(12): 5615. CrossRef
Optimization of Manufacturing Conditions of Pressure-Sensitive Ink Based on MWCNTs
Sung-Chul Park, In-Hwan Lee, Yong-Hwan Bae, Ho-chan Kim
Journal of the Korean Society of Manufacturing Process Engineers.2019; 18(8): 1. CrossRef
Influence of process parameters on temperature and residual stress distributions of the deposited part by a Ti-6Al-4V wire feeding type direct energy deposition process
Bih Lii Chua, Ho Jin Lee, Dong-Gyu Ahn, Jae Gu Kim
Journal of Mechanical Science and Technology.2018; 32(11): 5363. CrossRef
Influence of Angle of Corner Deposition on Temperature and Residual Stress Distributions in the Vicinity of the Deposited Region by a Ti-6Al-4V Wire-Feeding Type of Direct Energy Deposition Process
Bih Lii Chua, Ho Jin Lee, Dong-Gyu Ahn, Jae Gu Kim
Journal of the Korean Society for Precision Engineering.2018; 35(9): 853. CrossRef