Journal of the Korean Society for Precision Engineering

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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Development of an EEG-based Gait Recognition Classification CNN-BiLSTM Model for Brain-Computer Interfaces (BCI): Seohyun Lee, Yoonsung Jang, Hyunju Lee, Kisik Tae; J. Korean Soc. Precis. Eng. 2024;41(6):481-488.
Published online June 1, 2024; DOI: https://doi.org/10.7736/JKSPE.024.040

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Brain-computer interface (BCI) is a technology used in various fields to analyze electroencephalography (EEG) signals to recognize an individual"s intention or state and control a computer or machine. However, most of the research on BCI is on motor imagery, and research on active movement is concentrated on upper limb movement. In the case of lower limb movement, most of the research is on the static state or single movements. Therefore, in this research, we developed a deep-learning model for classifying walking behavior(1: walking, 2: upstairs, 3: downstairs) based on EEG signals in a dynamic environment to verify the possibility of classifying EEG signals in a dynamic state. We developed a model that combined a convolutional neural network (CNN) and a bidirectional long short-term memory (BiLSTM). The model obtained an average recognition performance of 82.01%, with an average accuracy of 93.77% for walking, 76.52% for upstairs, and 75.75% for downstairs. It is anticipated that various robotic devices aimed at assisting people with disabilities and the elderly could be designed in the future with multiple features, such as human-robot interaction, object manipulation, and path-planning utilizing BCI for control.

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Real-time Environmental Virtualization Method for Telemanipulation of Dynamic Objects Using VR Interface: Jae Hoon Jeong, Jin Gang Lee, Dan Kim, Hae Gyeom Choi, Dong Hun Lee; J. Korean Soc. Precis. Eng. 2024;41(5):333-339.
Published online May 1, 2024; DOI: https://doi.org/10.7736/JKSPE.024.038

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With the evolution of robotic technology, the expansion of operations into challenging environments underscores the growing need for effective teleoperation systems. In such an environment, robots or machines can improve the efficiency and safety of tasks by delivering more detailed and accurate information to workers through virtual reality (VR). Current teleoperation systems have limitations in providing a comprehensive understanding of the work environment. Accordingly, this study proposes a technology that utilizes VR to provide a high level of telepresence to workers and enable intuitive control. To achieve this, we introduce a pregenerated computer-assisted design model for static objects beyond the viewing area of RGB-D cameras and a method to update the point cloud of the target objects, which are dynamic objects, in real-time. By incorporating this information, we created a 3D visual map and delivered it to the operator in real-time through HMD, enabling the operator to clearly recognize the robot’s current location and surroundings. In addition, we introduced hand motion recognition through HMD viewpoints and VR controllers, allowing the operator to intuitively control the robot. These techniques can improve the efficiency and safety of remote work.

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A Development of Data Interface Middleware for Building Smart Factory: Hong Jin Jeong, Ki Hyeong Song, Bo Hyun Kim; J. Korean Soc. Precis. Eng. 2021;38(12):935-942.
Published online December 1, 2021; DOI: https://doi.org/10.7736/JKSPE.021.058

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SMEs encounter many difficulties in integrating and operating various information systems introduced to build smart factories. The source of this difficulty comes from integrated management of data interface between information systems. This research proposes a data interface middleware that can operate and manage various data interfaces between information systems in an integrated manner. First, this study identifies the types of information systems and operational information needed to build smart factories and analyzes the ways of data interface and requirements suitable for the manufacturing environment of SMEs. Structure and detailed functions of the data interface middleware are designed based on the analysis results. The proposed data interface middleware consists of the function layer, engine layer, and DB layer. The function layer is a set of functions for operating the middleware, and the engine layer comprises core engines for executing the functions. The DB layer manages all information that gathers when the data interface is executed. We applied the proposed middleware to connect data between the existing ERP and newly introduced smart factory package software in SMEs. Application results show that the associated data types are consistent in the two systems, and accuracy of the data parsing process is reliable.

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A Review of Intelligent Machining Process in CNC Machine Tool Systems
Joo Sung Yoon, Il-ha Park, Dong Yoon Lee
International Journal of Precision Engineering and Manufacturing.2025; 26(9): 2243. CrossRef
Improvement of Manufacturing Industry Work Environment Using Signage: Root Industry
Kyungjin Oh, Nayoung Lee, Daekwon Chung, Jinho Woo, Haeyeon Shin, Hunseop Kim, Ho Seong Lee, San Kim, SangJun Moon, Won-Shik Chu
Academic Society for Appropriate Technology.2022; 8(3): 117. CrossRef

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Improvement of Interface Diffusion in Cu thin films using SiN/CoWB Passivation Layer: Jung Woong Kim, Sean Jhin Yoon, Hyun Chan Kim, Youngmin Yun, Jaehwan Kim; J. Korean Soc. Precis. Eng. 2018;35(12):1163-1168.
Published online December 1, 2018; DOI: https://doi.org/10.7736/KSPE.2018.35.12.1163

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Silicon nitride/cobalt tungsten boride (SiN/CoWB) passivation layer improves mass transport rate at copper thin film layers of semiconductor wafers after chemical mechanical polishing process. This study evaluates mass transport at the interface between copper and passivation layers by stress relaxation method, followed by deduction of interface diffusivity via a kinetic model. For comparison, SiN/CoWB, SiN, silicon carbon nitride (SiCN) and silicon carbide (SiC) passivation layers are introduced. A thin layer of SiN/CoWB demonstrates an outstanding performance as diffusion retarding material, especially at high temperature. The order of stress relaxation in terms of passivation layers is SiN/CoWB < SiN < SiCN < SiC, implying the order of mass transport at the interface. Using the kinetic model, the diffusivities and activation energies regarding passivation layers are calculated and reveal a good agreement with experimental results.

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Development of Unified Interface for Multi-Vendors’ CNC Based on Machine State Model: Joo Sung Yoon, Il Ha Park, Jin Ho Sohn, Hoen Jeong Kim; J. Korean Soc. Precis. Eng. 2018;35(2):151-156.
Published online February 1, 2018; DOI: https://doi.org/10.7736/KSPE.2018.35.2.151

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The Human Machine Interface (HMI) is dependent on the Computerized Numerical Control (CNC). As a result, the HMI software is developed according to the interface method of each CNC in duplicate. Even though the same function of HMI software module is developed using the same data item, it must be implemented separately in different development environments. This is because each CNC has a different address system and provides unique data interface method. In this study, we proposed a unified interface system that can standardize and integrate data interface method to support the development of HMI software module applicable to machine tools adopting multi-vendors’ CNCs. To clearly define this work, we developed new parameters, methods, and address system based on the machine state model, composed of data elements of machine tool structure, process, and status, provides the same interface by capsulizing existing CNC interfaces. The proposed interface system is designed to provide an API (Application Programming Interface) in the form of a library. The implementation architecture is designed and details of the operating logic within the detailed components and interfaces are elaborated. The implementation and test results are illustrated to verify an application example of the proposed unified interface system.

Citations

Citations to this article as recorded by

The Digital Thread Framework for Implementing Intelligent Machining Applications
Jeongin Koo, Soohyun Nam, Hoon-Hee Lee, Dong Yoon Lee
Procedia CIRP.2024; 130: 301. CrossRef
Platform Supporting Intelligent Human–Machine Interface (HMI) Applications for Smart Machine Tools
Il-Ha Park, Joo Sung Yoon, Jin Ho Sohn, Dong Yoon Lee
International Journal of Precision Engineering and Manufacturing.2024; 25(5): 1073. CrossRef
Toward cyber-physical systems for monitoring and analyzing energy consumption of machine tools
Hyoung Seok Kang, Ju Yeon Lee
International Journal of Computer Integrated Manufacturing.2024; 37(12): 1495. CrossRef
Development of Digital twin for Plug-and-Produce of a Machine tending system through ISO 21919 interface
Yong-Keun Park, Joungmin Park, Sujong Kim, Dongyoon Lee, Sangyoon Lee, Jumyung Um
International Journal of Computer Integrated Manufacturing.2023; 36(10): 1449. CrossRef
Development of an Integrated Operation Management System for Multi-Vendors’ CNC Machine Tools Based on Standardized Interfaces to Support Smart Manufacturing
Joo-Sung Yoon
Journal of the Korean Society of Manufacturing Technology Engineers.2022; 31(3): 169. CrossRef