Journal of the Korean Society for Precision Engineering

Structural Analysis of a Cylindrical Superelastic Shape Memory Alloy Ligation Clip: Sang Wook Lee, Jae Hoon Kim, Jae Sung Cha, Ji Hoon Kang; J. Korean Soc. Precis. Eng. 2025;42(11):959-964.
Published online November 1, 2025; DOI: https://doi.org/10.7736/JKSPE.025.083

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This study outlines a structural design process for a cylindrical superelastic shape memory alloy (SMA) ligation clip. Although polymer-based clips are widely used, they face challenges related to long-term stability and limited radiopacity, highlighting the necessity for metal clips. By systematically modifying two key design variables—the hole offset ratio and the cut-off ratio—the proposed clip effectively reduces excessive stress concentration and enhances superelastic behavior. Finite element analyses indicate that the stress deviation in the two cross-sectional deformation regions decreased by 83.9%, and the martensitic transformation remained confined to a small area, demonstrating robust strain recovery within the superelastic range. In conclusion, the improved SMA clip successfully withstood internal pressures exceeding 15 psi without leakage, showcasing its superior ligation performance and potential for durable, reliable use in minimally invasive surgical procedures.

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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

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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 Elastic Modulus in Porous Structures Considering Materials and Design Variables Using Artificial Neural Network: Min Ji Ham, In Yong Moon; J. Korean Soc. Precis. Eng. 2024;41(11):897-903.
Published online November 1, 2024; DOI: https://doi.org/10.7736/JKSPE.024.093

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Predicting elastic modulus of a porous structure is essential for applications in aerospace, biomedical, and structural engineering. Traditional methods often struggle to capture complex relationships between material properties, design variables, and mechanical behavior. This study employed artificial neural networks (ANNs) to predict the elastic modulus of a porous structure based on various material and design parameters. An ANN model was trained on a dataset generated via finite element analysis (FEA) simulations, covering diverse combinations of material properties and design variables (e.g., porosity, structure types). The model demonstrated high accuracy in predicting the elastic modulus on a separate test dataset. Key findings included identification of significant design variables influencing the elastic modulus and the ANN model"s ability to generalize predictions to new data. This approach showcases that ANN is a powerful tool for designing and optimizing porous structures, providing reliable mechanical property predictions without extensive experimental testing or complex simulations. The proposed method can enhance design efficiency and pave the way for developing advanced materials with tailored mechanical properties. Future research will extend the model to predict other mechanical properties and incorporate experimental validation to verify ANN predictions.

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A Study on Creep Phenomenon after the Releasing of Injection Molded Articles: Yu Jung Kim, Hee-Seon Bang; J. Korean Soc. Precis. Eng. 2023;40(8):639-645.
Published online August 1, 2023; DOI: https://doi.org/10.7736/JKSPE.023.011

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Recently, with the expansion of application of polymer composite materials, high levels of deformation compensation actions have been developed. However, there is a problem of high-temperature viscoelasticity that occurs over time after completing the injection molding process. In this study, changes of mechanical properties of the Moldflow program for injection molding were analyzed to verify the viscoelasticity phenomenon through deformation analysis. In addition, deformation analysis of plastic injection molded products according to arrangement of three ribs was conducted and two products with different geometric shapes of the same function were compared. As a result, it was possible to reflect the viscoelastic effect by reducing the elastic modulus and shear modulus of the material. It was confirmed that the geometric shape with thick ribs formed in multiple longitudinal directions was mainly responsible. On the surface of the product where the rib arrangement was parallel and perpendicular to the flow direction, the orientation was orthogonal to the linear direction and the maximum residual stress was 81.17 MPa, which showed the largest value. It was judged that viscoelastic phenomena could be predicted and that an arrangement of parallel and perpendicular ribs that might intersect should be avoided.

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The Fabrication of a High-Aspect-Ratio Microfluidic Device for Microparticle Separation under Viscoelastic Fluid: Sung Woo Kim, Joo Yong Kwon, Jihong Hwang, Young Hak Cho; J. Korean Soc. Precis. Eng. 2022;39(10):725-730.
Published online October 1, 2022; DOI: https://doi.org/10.7736/JKSPE.022.053

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In this study, we propose a novel and simple fabrication method of the microfluidic device, with high-aspect-ratio (HAR) microchannel for microparticle separation under viscoelastic fluid flow. To fabricate the HAR (> 10) microfluidic device comprised of the Si channel and PDMS mold, basic MEMS processes such as photolithography, reactive ion etching and anisotropic wet etching of Si wafer were used, and then plasma bonding with mechanical alignment between the Si channel and PDMS mold was conducted. The width of the microchannels was determined by the difference between the Si channel width and the master width for the PDMS mold. On the other hand, the heights of the Si channel and PDMS mold could be controlled by the KOH etching time and spin-coating speed of SU-8, respectively. The HAR microfluidic device whose microchannel had 10 μm width and 100 μm height was successfully fabricated, and used to separate microparticles without other external forces. The effect on the particle focusing position and focusing width under viscoelastic fluid was investigated, depending on the flow rate and the microparticle size. It is expected that precise manipulation as well as high-throughput separation of microparticles, can be achieved using the microfluidic device with HAR microchannel.

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Process for the Fabrication of Nickel Material High Aspect-ratio Digital PCR Partition
GeeHong Kim, HyungJun Lim, SoonGeun Kwon, Hak-Jong Choi
Journal of the Korean Society for Precision Engineering.2024; 41(8): 663. CrossRef

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Application of Fractography and Finite Element Analysis Adopting Elastic Foundation Stiffness to Improve Fatigue Life of Main Shaft in Mechanical Press: Won-Jon Yang, Chung-Seog Oh; J. Korean Soc. Precis. Eng. 2022;39(5):363-369.
Published online May 1, 2022; DOI: https://doi.org/10.7736/JKSPE.022.011

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The main shaft of a mechanical press inevitably includes significant stress concentrations that can trigger severe mechanical damage and finally lead to failure under repetitive use. In this study, an efficient procedure to quantitatively evaluate the fatigue life of the shaft system including the main shaft and its support bearings, based on the macroscopic failure analysis of the main shaft broken during actual use, was investigated. For this purpose, the bearing support was modeled as an elastic foundation, and the elastic foundation stiffness value was varied to determine the optimal value that best simulates the failure behavior, especially with respect to the failure location and failure sequence, of an actual shaft. While the finite element mesh size was kept the same, only the effect of elastic foundation stiffness was investigated. The optimum value for the main shaft investigated in this study was approximately 60 N/mm³, and the fatigue life of the shaft was evaluated based on the conventional maximum principal stress theory. Based on this, two modified designs to enhance the fatigue life of the existing shaft are proposed.

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A Study on the Effect of Soft Wearable Suit Using Elastic Band: Eun Hye Cha, Seong Young Oh, Chul Un Hong, Mi Yu, Tae Kyu Kwon; J. Korean Soc. Precis. Eng. 2022;39(1):59-67.
Published online January 1, 2022; DOI: https://doi.org/10.7736/JKSPE.021.037

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Many of the workers are exposed to work that burdens the musculoskeletal system, and musculoskeletal diseases, such as low back pain, are increasing every year. Various muscle support systems, such as wearable robots, have been developed to prevent musculoskeletal diseases at industrial sites, but the system is bulky. Therefore, the total weight is high, it is inconvenient to wear, and the wearer cannot freely perform the activities when power is not supplied. In this paper, in order to compensate for the shortcomings of the hard-type wearable robot system, a soft-type wearable suit using an elastic band was manufactured so that it is light and portable, as it does not require an actuator. The experiment was conducted to verify the effect of muscle strength assistance through an experiment (Measurement of Maximum Waist Torque and Measurement of the Approximate Dose) on the effect of the soft wearable suit. In addition, by making two different types of elastic bands in the wearable suit, it was possible to classify the more effective types for the waist and lower extremities according to the elasticity by comparing the muscle strength assisting effect according to the elastic band.

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EMG and Usability Assessment of Adjustable Stiffness Passive Waist-Assist Exoskeletons for Construction Workers
Jung Sun Kang, Bo Ra Jeong, Eung-Pyo Hong, Bok Man Lim, Byung June Choi, Youn Baek Lee, Yun Hee Chang
International Journal of Precision Engineering and Manufacturing.2025; 26(1): 227. CrossRef
Development of lifting-assistive passive functional pants for construction works
Jin Zhi Chen, Jeong Eun Yoon, Zi Ying Liu, Sung Kyu Lee, Sumin Helen Koo
Textile Research Journal.2025;[Epub] CrossRef
Effects of the Wearable Assistive Suit on Muscle Activity during Lifting Tasks
Kwang Hee Lee, Chul Un Hong, Mi Yu, Tae Kyu Kwon
Journal of the Korean Society for Precision Engineering.2024; 41(1): 47. CrossRef
Design development and evaluation of arm movement-assistive suits for lifting and movement for industrial workers considering wearability
Jiwon Chung, Jung Eun Yoon, Soah Park, Hyunbin Won, Suhyun Ha, Sumin Helen Koo
International Journal of Industrial Ergonomics.2024; 103: 103616. CrossRef
Enhancing wearability: designing wearable suit platforms for industrial workers
Jiwon Chung, Hyunbin Won, Hannah Lee, Soah Park, Hyewon Ahn, Suhyun Pyeon, Jeong Eun Yoon, Sumin Koo
International Journal of Clothing Science and Technology.2024; 36(3): 526. CrossRef

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Frequency Related Verification of MPR Model of Elastomeric Bushing in Torsional Mode: Seong Beom Lee; J. Korean Soc. Precis. Eng. 2021;38(12):959-963.
Published online December 1, 2021; DOI: https://doi.org/10.7736/JKSPE.021.082

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Elastomeric bushings are structural elements that are used in automotive suspension systems. An elastomeric bushing is a hollow cylinder that is contained between an outer steel cylindrical sleeve and an inner steel cylindrical rod. The outer steel cylindrical sleeve is connected to the components of the suspension system and is used to transfer forces and moments from the wheel to the chassis. The elastomeric material reduces the shock and vibration in this connection. Dynamic simulations of the automotive suspension system involve the interaction between many components. The accurate determination of the transmitted forces and moments between the components, the motion of the components, stress in the components, and energy dissipation is affected by the quality of the bushing model. Several Pipkin-Rogers models have been proposed for the axial mode, radial mode, and torsional mode and modified Pipkin-Rogers models have been proposed for the axial mode and torsional mode. In this research, the modified Pipkin-Rogers model for the torsional mode was verified in a frequency-related rotational angle control test. The results showed that the moment outputs of the modified Pipkin-Rogers model were in very good agreement with those of the Pipkin-Rogers model in the sinusoidal rotational angle control test.

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Analysis on Material Behavior of Metal Additive Manufactured Lattice Structures under Quarter Compression Test: Qingye Jin, Simo Yeon, Yong Son, Sanghu Park; J. Korean Soc. Precis. Eng. 2021;38(9):667-673.
Published online September 1, 2021; DOI: https://doi.org/10.7736/JKSPE.021.061

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With the development of Additive Manufacturing process, lattice structures have recently been fabricated with fine quality. Lattice structures have unique performances which encompass various elastic responses. In this study, shear characteristics of the lattice structures (BCC and OTC) fabricated by SLM process, under optimized manufacturing conditions, were analyzed by 1/4 compression tests. As a result, several fracture modes and elastic configurations were found by comparing the compression test results of various lattice structures. In addition, the lattice structures possessed certain shear elasticity and normal elasticity among different types of lattices at elastic region when shearing. As the 1/4 compression test was simulating the lattice structure on concentrate load or shearing load, the test represented shock introspection characteristics of the lattice inner structure.

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Measurement of Mechanical Properties according to the Thickness of Anodic Aluminum Oxide through Nanoindentation Test: Jongseon Choi, Hyundo Hwang, Jonghyeon Jeong, Woonbong Hwang; J. Korean Soc. Precis. Eng. 2021;38(3):203-208.
Published online March 1, 2021; DOI: https://doi.org/10.7736/JKSPE.020.105

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Anodic aluminum oxide (AAO) is widely used in various industrial fields to increase the mechanical property or corrosion resistance of the product surface. In this study, mechanical properties were measured according to the thickness of AAO through the nanoindentation test. The maximum indentation load, elastic modulus, and hardness were measured for different thicknesses of AAO. It was confirmed that the majority of the mechanical property values increased with the thickness. Various fracture shapes based on the thickness were analyzed by observing pressure marks on the surface using FE-SEM equipment. Apparently, it is proposed that the optimum AAO thickness with desired mechanical properties can be obtained, which is expected to possess immense economic value as per the optimization of the production time of AAO based products.

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In-situ Wired and Wireless Material Testing System with Nanometer-level Displacement Control
Kyoung Seok Park, Pill Ho Kim, Chung-Seog Oh
Journal of the Korean Society for Precision Engineering.2024; 41(11): 881. CrossRef

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Design and Analysis of Variable Stiffness Joint for Railway Vehicles Using Magneto-Rheological Elastomer: Yujeong Shin, Dahoon Ahn; J. Korean Soc. Precis. Eng. 2021;38(2):131-137.
Published online February 1, 2021; DOI: https://doi.org/10.7736/JKSPE.020.069

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The magnetorheological material changes its characteristics according to the external magnetic field. Magnetorheological elastomer existing in the solid phase has micrometer-sized magnetically responsive particles inside. When a magnetic field is applied by a permanent magnet or electromagnet nearby, it can exhibit stiffness that changes according to the strength of the magnetic field. Many previous studies focused on verifying the variability of the material"s characteristics. However, this study newly proposed a variable stiffness joint for the suspension system of railway vehicles using a magnetorheological elastomer, as a basic study of magnetorheological elastomer for a mechanical component. Based on the characteristics test of the magnetorheological elastomer, the variable joint was designed to have the same structure as the conventional guide arm joint of a railway vehicle. Particularly, to overcome the low magnetic field strength, which may be a problem in the previous research, and to implement uniform magnetic field distribution, the electromagnet was designed to make direct contact with the magnetorheological elastomer. A mathematical model was established and a finite element method verified the model, resulting in an average magnetic flux density of 300 mT, which means 30% stiffness change at 15% shear strain.

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Investigation of wheel-rail wear reduction by using MRF rubber joints with bidirectional adjustable stiffness
Ning Gong, Jian Yang, Weihua Li, Shuaishuai Sun
Smart Materials and Devices.2025;[Epub] CrossRef

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Modified Pipkin-Rogers Modeling of Elastomeric Bushing in Torsional Mode: Seongbeom Lee; J. Korean Soc. Precis. Eng. 2020;37(12):905-910.
Published online December 1, 2020; DOI: https://doi.org/10.7736/JKSPE.020.076

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Elastomeric bushings are structural elements and used in automotive suspension systems. An idealized bushing is an elastomeric hollow cylinder between an outer steel cylindrical sleeve and an inner steel cylindrical rod. The outer sleeve is connected with the components of the suspension system and transfer forces and moments from the wheel to the chassis. The accurate determination of the transmitted forces and moments among autocomponents, the motion of the components, the stresses in the components, and energy dissipation are affected by the quality of the elastomeric bushing model. Force- Displacement relation, moment-rotational angle relation, and coupled relations for elastomeric bushings are imperative for multi-body dynamics simulations. The boundary value problem in the bushing response leads to force-displacement relation and moment-rotational angle relations which require extensive computation time for implementation. Herein, an explicit moment-rotational angle relation has been introduced for use in multi-body dynamics simulations, a modified Pipkin-Rogers model is proposed and a boundary value problem is formulated for torsional mode elastomeric bushing response. Lianis" experimental equation and Pipkin-Rogers model are used for numerical experimental research. The proposed method and the prediction of the proposed moment-rotational angle relation are observed to exhibit excellent agreement with the original results.

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Frequency Related Verification of MPR Model of Elastomeric Bushing in Torsional Mode
Seong Beom Lee
Journal of the Korean Society for Precision Engineering.2021; 38(12): 959. CrossRef

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Reliable Replication Molding Process for Robust Mushroom-Shaped Microstructures: Joon Hyung An, Ji Seong Choi, Seong Min Kang; J. Korean Soc. Precis. Eng. 2020;37(11):855-860.
Published online November 1, 2020; DOI: https://doi.org/10.7736/JKSPE.020.062

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In this paper, we present a simple and robust fabrication method for mushroom-shaped microstructures using diverse polymers with various modulus of elasticity. Through the repeated replica molding process, we fabricated the same PDMS mushroom structure negative mold as the prepared silicon master mold. To evaluate the fabricating stability of the fabricated PDMS negative mold, the mushroom-shaped structures were replicated from the mold using six types of polymer resins with different elastic modulus and we measured superhydrophobic properties on the samples. All the fabricated samples exhibited superhydrophobicity, and we proved the structural stability of the proposed replication method through the measured SEM images, contact angles on the samples, and theoretical analysis based on the structural shape.

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Mastering of NIL Stamps with Undercut T-Shaped Features from Single Layer to Multilayer Stamps
Philipp Taus, Adrian Prinz, Heinz D. Wanzenboeck, Patrick Schuller, Anton Tsenov, Markus Schinnerl, Mostafa M. Shawrav, Michael Haslinger, Michael Muehlberger
Nanomaterials.2021; 11(4): 956. CrossRef

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Method to Calculate the Maximum Elastic Displacement on Double Blast Reinforced Concrete Door Supported by 3 Sides: Kwan Bo Shim, Taek Sung Lee; J. Korean Soc. Precis. Eng. 2019;36(12):1165-1172.
Published online December 1, 2019; DOI: https://doi.org/10.7736/KSPE.2019.36.12.1165

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Displacement ductility and rotational ductility are used, to verify the performance of blast doors subjected to explosive loads. The values of these performance items are calculated by measuring the maximum elastic displacement in the laboratory, and the maximum displacement during the explosion test. To attain the maximum elastic displacement, the finite element analysis and the load distribution method are applied. In applying the load distribution method, the behavior of a blast door along a width direction is converted to a cantilever beam and along a height direction to a simply supported beam. The results by the load distribution method are verified by a finite element analysis and compared with those by a plate theory.

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Design of Frame Type Blast Door Reflecting Explosion Proof Test
Kwan Bo Shim, Taek Sung Lee
Journal of Korean Society of Steel Construction.2020; 32(2): 67. CrossRef
Optimized Design of Grid Type Explosion-Proof Door Using Load Distribution Method
Kwan Bo Shim, Byeong Jin Kim, Hyunjoo Koo
Journal of Korean Society of Steel Construction.2020; 32(6): 397. CrossRef
Design of Concrete Filled Steel Plate Door by Design of Experiment in Load Distribution Method
Kwan Bo Shim, Byeong Jin Kim, Taek Sung Lee
Journal of Korean Society of Steel Construction.2020; 32(6): 351. CrossRef

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Measurement of the Young’s Modulus of a Ceramic Thin-Film Using Gigahertz Longitudinal Bulk Waves: Yun Young Kim; J. Korean Soc. Precis. Eng. 2019;36(6):531-535.
Published online June 1, 2019; DOI: https://doi.org/10.7736/KSPE.2019.36.6.531

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Picosecond ultrasonic evaluation on the Young’s modulus of a ceramic thin-film was performed in the present study. A 100nm thick silicon nitride thin-film was deposited on a silicon wafer using the plasma enhanced chemical vapor deposition technique and gigahertz-frequency longitudinal bulk waves were excited in the film using a femtosecond laser setup. A thermoelastic equation was numerically solved using the finite difference method and compared to the experimental data to estimate the elastic property of the film. Results show that the present measurement technique can effectively evaluate the film’s Young’s modulus and it is recognized that the modulus is 60-70% lower than that of its bulk status. This study is expected to provide a way to characterize nanoscale ceramics with very high spatial and temporal resolutions for the design and analysis of microelectromechanical systems and thin-film based devices.