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Performance Study of Dielectric Elastomer Actuators with Varying Thickness of Carbon Nanotube Electrodes and Pre-stretch Ratios
Mingyu Kang, Joong-Hyun Park, Jong-An Choi, Jingu Jeong, Soonjae Pyo
J. Korean Soc. Precis. Eng. 2025;42(10):817-823.
Published online October 1, 2025
DOI: https://doi.org/10.7736/JKSPE.D.25.00004

This study examines how two key design parameters—the pre-stretch ratio and the thickness of the carbon nanotube (CNT) electrode—affect the actuation performance of dielectric elastomer actuators (DEAs). DEA samples are created with varying pre-stretch levels (50% and 125%) and different amounts of CNT spray coating (4 and 8 mg), and their threshold voltages and areal strains are quantitatively assessed. The experimental results indicate that higher pre-stretch ratios result in lower threshold voltages and greater areal deformations, while increased CNT thickness typically reduces actuator deformation due to enhanced mechanical stiffness. The combination of a high pre-stretch ratio and low CNT loading demonstrates improved electro-mechanical responsiveness at moderate voltages. These findings underscore the interconnected effects of structural and electrode design on DEA performance, offering practical design guidelines for optimizing soft actuator systems. This research lays a solid foundation for future applications of DEAs in haptic interfaces, wearable actuators, and soft robotics.

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Prediction of Steel Plate Deformation in Line Heating Process Using Conditional Generative Adversarial Network (cGAN)
Young Soo Yang, Kang Yul Bae
J. Korean Soc. Precis. Eng. 2025;42(6):411-420.
Published online June 1, 2025
DOI: https://doi.org/10.7736/JKSPE.025.010
This study proposed a conditional generative adversarial network (cGAN) model for predicting steel plate deformation based on heating line positions in a line heating process. A database was constructed by performing finite element analysis (FEA) to establish relationships between heating line positions and deformation shapes. Deformation shapes were converted into color map images. Heating line positions were used as conditional labels for training and validating the proposed model.
During the training process, generator and discriminator loss values, along with MSE and R² metrics, converged stably, demonstrating that generated images closely resembled the actual data. Validation results showed that predicted deformation magnitudes had an average relative error of approximately 3% and a maximum error of less than 7%. These findings confirm that the proposed model can effectively predict steel plate deformation shapes based on heating line positions in the line heating process, making it a reliable predictive tool for this application.
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Microfluidic chips have become a critical component in advanced applications such as biochemical analysis, medical diagnostics, drug development, and environmental monitoring because of their ability to precisely control fluid flow at the microscale. The functionality of these chips is highly dependent on the precision and dimensional stability of microchannel structures formed on them. While injection molding is an efficient method for a mass production of microfluidic chips, it is required to minimize undesirable deformation due to thermal and mechanical stresses, which can degrade the overall performance. This study investigated global (Macro-scale) and local (Micro-scale) deformation behaviors of injection-molded microfluidic chips. Effects of processing parameters, including mold temperature, melt temperature, filling time, and packing pressure, were investigated. The Taguchi-based design of experiments approach was employed to systematically analyze these effects and to determine optimal conditions to minimize deformation.
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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
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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Study on of Friction and Degradation Characteristics of TPV Glass Run Channel
Su-Bin Cha, Junho Bae, Koo-Hyun Chung
J. Korean Soc. Precis. Eng. 2023;40(11):891-897.
Published online November 1, 2023
DOI: https://doi.org/10.7736/JKSPE.023.078
Recently, the demand for electric vehicles is intensively increasing in accordance with environmental issues in automotive industries. Given that noise level from the electric vehicles is significantly lower than that from conventional vehicles with internal combustion engine, noise management has become more critical. Conventionally, glass run channel (GRC) is used to block the noise and contaminants from outside of vehicle. In this work, the friction and degradation characteristics of GRC with thermoplastic vulcanizate substrate were assessed. The tests were performed using the reciprocating tribo-tester developed to replicate the contact sliding between GRC and window glass. Also, the test conditions were determined in consideration of operating condition of GRC. As a result, the plastic deformation of the lips due to creep and wear of the slip coating deposited on the lip surface were found to be major degradation mechanisms. Furthermore, it was shown that the friction and degradation increased significantly due to the misalignment between GRC and window glass, associated with the significant increase in the reaction force. The results of this work provide fundamental understanding of the degradation characteristics of GRC, and therefore are expected to be useful for the design of GRC with improved performance.
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The design of a substrate greatly affects the residual stress distribution and the deformation behavior of the repaired region by a directed energy deposition (DED) process. The objective of the present study was to investigate effects of edge length and slope of the substrate on residual stress and deformation characteristics in the vicinity of the repaired region for the repair of the straight damaged region using a DED process. Two-dimensional finite element analysis (FEA) was carried out using SYSWELD. Materials of the substrate and deposited powders were AISI 1045. The maximum residual stress during the deposition decreased when the edge length of the substrate increased, but increased when the slope of the substrate increased. The residual stress after a cooling state increased when the edge length and the slope increased. The displacement of the specimen increased when the slope of the substrate augmented. Finally, the methodology to select a proper edge length and slope of the substrate are discussed in this study.

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  • Artificial Intelligence Technologies and Applications in Additive Manufacturing
    Selim Ahamed Shah, In Hwan Lee, Hochan Kim
    International Journal of Precision Engineering and Manufacturing.2025; 26(9): 2463.     CrossRef
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Analysis of Acoustic Emission (AE) Signal Characteristics of the Magnesium Alloy Sheet (AZ31B) in the Tensile Deformation
Yong Ho Song, So Chan An, Jae Hyeong Yu, Wan-Jin Chung, Chang-Whan Lee
J. Korean Soc. Precis. Eng. 2023;40(1):39-47.
Published online January 1, 2023
DOI: https://doi.org/10.7736/JKSPE.022.091
In this study, acoustic emission (AE) signals associated with the behavior of materials in the magnesium alloy (Mg AZ31B) tensile test were analyzed. The AE sensor was attached with the material to measure the AE signals. During the tensile experiment, the AE sensor measured the elastic waves generated inside the specimen. The AE parameters, such as, the signal energy, duration, and frequency centroid, were studied. We also analyzed the effect of the materials size and tensile speed on the AE signals. As a result, the lowest frequency centroid value occurred at the yield and fracture points. As the width and length of the specimen increased, the number of hit counts increased and the peak frequency occurred. Other AE parameters, such as, the duration and frequency centroid, were not affected. As the tensile speed increased, the hit decreased and the frequency centroid decreased in the elastic region. It was found that in the detection of the yield and fracture deformation, the number of counts, and frequency centroid were appropriate.
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Temperature and Strain Rate Controls of AISI 4340 based on a 3D Processing Map in a Hot Forging Process
Joon Hee Park, Dong Hwi Park, Sang Yun Shin, Naksoo Kim
J. Korean Soc. Precis. Eng. 2022;39(9):691-700.
Published online September 1, 2022
DOI: https://doi.org/10.7736/JKSPE.022.071
This paper investigated the hot deformation behavior of an AISI 4340 material through high-temperature compression experiments. The compression tests were performed to obtain stress-strain curves at processing temperatures of 900, 1,000, 1,100, and 1,200℃, and the strain rates of 0.01, 0.1, 1, and 10 s-1 up to a true strain of 1.0 in the high-temperature compression mode of Gleeble® 3,500. A novel 3D processing map, constructed through power dissipation efficiency and Ziegler"s instability criterion, is proposed. The deformation behavior was analyzed by observing changes in the microstructure from the high-temperature compression tests. Electron back scatters diffraction (EBSD) was used to characterize the microstructures for various processing parameters. The process workability of finite element analysis (FEA) was examined in the deformation flow instability map in the three-dimensional space for each strain. As a result, each particle"s strain rate and temperature of FEA data can be observed in a three-dimensional flow instability map to control the temperature and process speed to avoid unstable zones.
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Investigation of Planarization Using Real Contact Area Measurement in CMP Process
김민지 , Seonho Jeong, 신영일 , Youngwook Park, Haedo Jeong
J. Korean Soc. Precis. Eng. 2022;39(8):547-555.
Published online August 1, 2022
DOI: https://doi.org/10.7736/JKSPE.022.028
Chemical Mechanical Planarization (CMP) is an essential process for device integration and planarization in a semiconductor manufacturing process. The most critical function in the CMP process, is to predict and cover the geometrical characteristics of various sizes and densities, of patterned wafers for local and global planarization. To achieve the wafer-level and die-level planarization, it is necessary to understand the contact mechanism between the CMP pads and the macro-scale patterns. In the macro-scale pattern, pad deformation is divided into two layers: an asperity layer and a bulk pad layer. Through bulk pad deformation, asperity contact distribution within the pattern is predicted. In this paper, the distribution of asperity contact according to the pattern geometrical characteristics was analyzed, through large-area real contact area (RCA) measurement. Bulk pad deformation was predicted by analyzing RCA distribution according to pattern geometry such as pattern size and density, pattern shape and step height according to the polishing time, and applied pressure. Additionally, through the distribution of the contact area and the number of contact points, the rounding phenomenon and planarization characteristics in the pattern CMP were predicted.
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A Study on the Plastic Deformation by Collision of a Safety Coupling under Overload
Hyeon Jun Jung, Taek Jin Jang, Byung Ro Kim, Sungmuk Kim, Jong-Bong Kim
J. Korean Soc. Precis. Eng. 2021;38(3):187-193.
Published online March 1, 2021
DOI: https://doi.org/10.7736/JKSPE.020.101
Plastic deformation of balls in safety coupling by collision with V-Hole was investigated in the current study. Generally, when the applied torque is greater than the maximum allowable torque, balls in V-Hole get out from the holes and the coupling loses the torque transfer capability. After balls are out from the V-Holes, the balls and V-Hole rotate at a different velocity. When balls meet the next V-Hole, they collide into the wall of the V-Hole. Due to this collision, plastic deformation and wear take place. The plastic deformation and wear may reduce the torque transfer capability of the safety coupling. The reduction in torque transfer capability was observed in the experiment. In this study, plastic deformation of balls and flange was investigated through dynamic analysis of the safety coupling. Also, the effect of relative rotational velocity on the plastic deformation was investigated.
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A Study on the Optimum Design of the Spindle Taper Angle by Chucking Force of a 2-Head Simultaneous Grinding Machine
Choon-Man Lee, Jeong-Hak Lee, Ho-In Jeong, Jeong-Hun Lee
J. Korean Soc. Precis. Eng. 2021;38(2):139-144.
Published online February 1, 2021
DOI: https://doi.org/10.7736/JKSPE.020.079
In recent years, the machine industry has demanded high precision of the processed products and high efficiency of production due to the rapid development of technology. The grinding machine is being studied in many countries. The typical grinding machine is processed in the order of one side each. However, a 2-head simultaneous grinding machine processes both sides at the same time. Therefore, it has reduced processing time and improved precision. In this study, the overall structural analysis of a 2-head simultaneous grinding machine with high precision and high efficiency of productivity was performed. For high precision of the 2-head simultaneous grinding machine, the spindle taper angle was analyzed and optimized. When the spindle taper angle was 16 degrees, it had the highest chucking force. Therefore, the spindle had high precision as the spindle taper had the strongest force to chuck the collet. The analysis results can be applied to further develop the 2-head simultaneous grinding machine.

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  • Research on Stiffness Analysis and Technology of the Heavy Spidle Top
    Yongkang Wang, Bingwei Gao, Wenlong Han, Shilong Xue
    Current Materials Science.2024; 17(5): 540.     CrossRef
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Influence of the Deformation on the Microstructure and Mechanical Properties of TBF Steel
Nguyen Duong Nam, Tran Phap Dong, Tran The Nam, Nguyen Hong Hai, Pham Mai Khanh
J. Korean Soc. Precis. Eng. 2020;37(8):595-600.
Published online August 1, 2020
DOI: https://doi.org/10.7736/JKSPE.019.054
The article presents the influence of the deformation process on the microstructure and mechanical properties of low carbon alloy steel which heat treatment by TBF processing. When the samples are deformed at different levels: 20, 40, and 80%. The research results show that when the sample was deformed with the 80%, the highest strength was 800 MPa, the highest elongation was 36%, the product between the strength and the elongation (Rm*A) was the highest, 28774 MPa*%. This alloy deformed at a level of 80%, the content of austenite in this microstructure of this alloy was the highest about 16%. The content of ferrite was 52% with the average particle size of ferrite was 6.4 μm, the particle of residual austenite was 2 μm. The results of the microstructure have contributed to improving the mechanical properties of steel. The phase which was improved the mechanical properties of this alloy had grain size and dispersed.

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  • Elektrik direnç punta kaynağı ile birleştirilen TBF/DP600 çeliklerinin mikroyapı ve mekanik özelliklerinin incelenmesi
    Hakan AYDIN, İmren OZTURK YILMAZ, Abdullah BİLİCİ
    Gazi Üniversitesi Mühendislik Mimarlık Fakültesi Dergisi.2022; 37(2): 609.     CrossRef
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Finding Ways to Deform Fine Patterns Fabricated by UV Curable Resin
Woo Young Kim, Su Hyun Choi, Seonjun Kim, Young Tae Cho
J. Korean Soc. Precis. Eng. 2020;37(4):291-296.
Published online April 1, 2020
DOI: https://doi.org/10.7736/JKSPE.019.141
In this study, experiments were performed to determine if the pattern fabricated by the UV nano imprint process could be modified using additional processes such as surface treatment. We wanted to confirm the fabrication possibility of a special pattern such as the reverse trapezoidal shape difficult to produce because of the releasing problem. The UV ozone treatment (Hydrophilic Treatment) and OTS coating (Water Repellent Treatment) were used and shape modification occurred under controlled treatment time. As a result of performing the UV ozone treatment for 30 minutes or more on a micro pattern manufactured by UV curing resin of PUA series, the contraction phenomenon of the micro structure occurred and the shrinkage was dependent on treatment time. When the OTS treatment was performed, the surface of the microscale pattern could be roughened. When the nanoscale pattern was treated, the pattern change could be induced. It was possible to partially cure the resin by adjusting the UV absorption using dye material, and the deformation of the pattern was made by an additional pressing process. As a result of the experiment of the various methods causing the shape change of the cured pattern, the possibility of the methods was verified.
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Effects of Temperature and Humidity on Electrical Conductivity of Flexible Printed Electrodes with Static Mechanical Deformations
Jung Yeop Kim, Cheol Kim, Chung Hwan Kim
J. Korean Soc. Precis. Eng. 2019;36(7):611-616.
Published online July 1, 2019
DOI: https://doi.org/10.7736/KSPE.2019.36.7.611
Printed electronics is a technology which is used for manufacturing flexible electronic devices dubbed as next-generation electronics such as wearable applications. To commercialize them, it is important to guarantee their electrical performance under various environmental conditions such as temperature and humidity. Moreover, flexible electronic devices usually undergo mechanical deformations such as bending and twisting, hence, it is necessary to observe the electrical performance of flexible devices under mechanical deformation considering both temperature and humidity. The effects of temperature and humidity on flexible printed electrodes, as an example of the simplest flexible electronics, under static deformation of bending and twisting are studied. Electrodes that do not deform are also strongly affected by temperature and humidity, and the increase in resistances of the electrodes with deformation is highest when twisting. The magnitude of static deformation does not affect the conductivity. The effect of line width is important for the twisting deformation. To commercialize printed electronics devices, the effects of temperature and humidity should be considered, with further consideration of the effects of mechanical deformation on the design of the devices.

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  • Enhancements of Humidity and Gap-Sensing Properties of Coil-Shaped SnO2 Based on Layered Sputtering Method
    Yang Yang, Luheng Wang
    IEEE Transactions on Instrumentation and Measurement.2024; 73: 1.     CrossRef
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Electrochemical Performance Analysis of Heat Treatment of Metal-Air Battery
Ikwhang Chang, Nokeun Park, Guntae Kim
J. Korean Soc. Precis. Eng. 2018;35(12):1137-1140.
Published online December 1, 2018
DOI: https://doi.org/10.7736/KSPE.2018.35.12.1137
The objective of this study was to investigate the effect of heat treatment on electrochemical performance of aluminum (Al)-air battery. We prepared a pure Al and an annealed Al under an annealing environment [a mixture gas of Ar (97%) and H2 (3%)] of 400°C for 1 hr. Based on electron backscatter diffraction analysis of Al at the anode, the relative misorientation of the pristine Al was higher than that of the annealed Al. Electrochemical performances of the pristine Al-air and the annealed Al-air were also compared. The annealed Al-air battery showed slightly higher power density than the pristine Alair battery. These results suggest that annealing with heat treatment is an important process to improve the electrochemical performance of aluminum-air battery.
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