Journal of the Korean Society for Precision Engineering

Suppression of Interfacial Side Reactions and Performance Enhancement of NCA Cathodes via LNO Deposition Using Particle ALD: Min-ji Kim, In-suk Song, Hyo-jun Ahn, Sun-min Kim, Young-Beom Kim; J. Korean Soc. Precis. Eng. 2025;42(10):851-859.
Published online October 1, 2025; DOI: https://doi.org/10.7736/JKSPE.025.025

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Improving the interfacial stability between cathode active material (CAM) and solid electrolyte (SE) is essential for enhancing the performance and durability of all-solid-state batteries (ASSBs). One promising method to achieve this is through surface coating with a chemically stable ion conductor, which helps suppress interfacial side reactions and improve long-term cycling stability. In this study, we deposited a uniform LiNbO3 (LNO) protective layer on NCA using particle atomic layer deposition (Particle ALD). This technique utilizes a self-limiting growth mechanism to ensure precise thickness control. We characterized the structural and chemical properties of the coated CAM with X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), confirming the successful formation of a uniform LNO layer. Electrochemical evaluations revealed that LNO@NCA exhibited significantly improved capacity retention, maintaining 68.1% after 50 cycles at a 1C rate, compared to just 56.5% for the uncoated sample. This enhancement is attributed to the LNO layer's effectiveness in mitigating electrochemical side reactions. These findings demonstrate that Particle ALD-derived LNO coatings are an effective strategy for stabilizing CAM|SE interfaces and extending the cycle life of high-energy ASSBs.

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Enhancing Chatter Vibration Analysis in Turning Processes through Advanced Multiple-denoising Wavelet Techniques: Chanikan Pomusa, Bandit Suksawat; J. Korean Soc. Precis. Eng. 2025;42(4):273-284.
Published online April 1, 2025; DOI: https://doi.org/10.7736/JKSPE.024.128

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This study investigated the natural frequency of a self-excited vibrating workpiece and cutting tool using a hammer impact test to acquire vibration data. Time-domain cutting vibration data were converted to the frequency domain using FFT. The workpiece signal exhibited a high amplitude, peaking at 392 Hz, while the cutting tool signal presented a peak at 930 Hz. Stability Lobe Diagrams were constructed to assess dynamic stability. Cutting experiments revealed an obvious relationship between spindle speed and signal amplitude, with higher speeds leading to larger amplitudes. Frequency analysis revealed a peak near the cutting tool's 900 Hz natural frequency. Smoother surface finishes were observed at 0.15 mm cutting depth, while 0.2 mm resulted in a wavy surface, indicating chatter. To investigate chatter frequency and reduce noise, a multiple-denoising method combined Bior 3.7 and DB10 wavelets to reduce amplitude and improve signal representation, especially for non-smooth features. The proposed method aimed to reduce the 900 Hz cutting tool’s natural frequency. Results showed a clear chatter frequency at 450-480 Hz for 0.2 mm depth cuts at spindle speeds of 500, 1,000, and 1,400 rpm. The proposed method exhibited high efficiency, achieving the higher signal-to-noise ratio and lower mean-square error than Bior 3.7 and DB10 wavelet denoising techniques.

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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

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Progresses in Pneumatic Temperature Control Technique for Ultra-Precise Control and Measurement of Thermal Environment: Bomi Nam, Wukchul Joung; J. Korean Soc. Precis. Eng. 2024;41(10):759-776.
Published online October 1, 2024; DOI: https://doi.org/10.7736/JKSPE.024.081

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In this paper, we introduce a new pneumatic temperature control technique and its application to precision thermometry. The method controls temperature by adjusting gas pressure through the unique thermohydraulic linkage of the pressure-controlled loop heat pipe (PCLHP). Due to this temperature-pressure linkage, the PCLHP-based pneumatic temperature control achieves exceptional control speed, stability, and precision. To fully understand this method, we systematically investigated the effects of various influencing parameters, such as heat load, sink temperature, and rate of pressure change, on the stability of temperature control. In addition, we successfully achieved closed-type pneumatic temperature control using a mechanically-driven gas pressure controller. We also developed a hybrid PCLHP that incorporates a heat pipe liner into the isothermal region to further improve the temperature uniformity of the pneumatically-controlled temperature field. With this technique, we significantly improved the accuracy of the fixed point of the International Temperature Scale of 1990 by using inside nucleation of the freezing temperature of tin and determining the liquidus temperature of tin. In this paper, we summarize the results of these diverse efforts in characterizing the pneumatic temperature control technique, along with theoretical analyses.

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Progresses in Ultra-Precise Temperature Control and Thermometry Techniques: Wukchul Joung; J. Korean Soc. Precis. Eng. 2021;38(12):905-915.
Published online December 1, 2021; DOI: https://doi.org/10.7736/JKSPE.021.053

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In this work, recent advances in temperature control techniques and the resulting contemporary progress in precision thermometry are addressed together with a broad review of traditional temperature control methods. Particular emphases are placed on clarification of the nature of temperature control and its classification, and the relevant technical issues are addressed based on this clarification and classification. Being a thermodynamic quantity having the same dimension as energy, temperature of an object is traditionally controlled by means of the changing rate of energy (Heat) transfer; however, this approach has led to a slow, less stable, and uneven temperature field due to inherent limits caused by finite properties of materials. To overcome this problem, thermodynamic characteristics of two-phase heat transfer devices, such as heat pipes and loop heat pipes, have been extensively employed where high-speed nature of fluid flow was exploited to realize a uniform temperature field, and unique thermodynamic linkage between saturation temperature and pressure was successfully applied to attain a fast, stable, and predictable temperature control of a finite-sized isothermal space. Representative examples and applications are provided in the context of unique features of the introduced contemporary temperature control techniques, which caused significant scientific strides in the related fields.

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Progresses in Pneumatic Temperature Control Technique for Ultra-Precise Control and Measurement of Thermal Environment
Bomi Nam, Wukchul Joung
Journal of the Korean Society for Precision Engineering.2024; 41(10): 759. CrossRef

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An Integrated Control System for Disaster Response Robot based on Multiple ROS Core considering Network Instability: Kyon-Mo Yang, Jin-Ho Suh, Ji-Won Lee, Jinhong Noh, Min-Gyu Kim, Kap-Ho Seo; J. Korean Soc. Precis. Eng. 2021;38(10):741-748.
Published online October 1, 2021; DOI: https://doi.org/10.7736/JKSPE.021.063

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This paper proposes an integrated control system for multi-disaster response robots based on Robot Operating System (ROS). The contributions of this paper were as follows: 1) A multi-score-based system concept was proposed in consideration of network instability issues which might frequently occur in compound disaster environments; 2) A detailed ROS based software structure was implemented to apply the proposed system to real robots; 3) Hardware cockpit and graphical user interface (GUI) for an operator were implemented; 4) through the experiment, the problem of the system based on common ROS structure, the out-of-control state, was confirmed and we verified the proposed system using the scenario.

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Comparative Study of Gait Stability Using COM-COP Inclination Angle Changes of Elderly: Byeong Chan Cho, Tae Soo Bae; J. Korean Soc. Precis. Eng. 2021;38(7):521-528.
Published online July 1, 2021; DOI: https://doi.org/10.7736/JKSPE.021.001

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The current method of gait analysis has several limitations for determining gait stability, such as a complicated preparation process, repeated experimental procedures that are time-consuming, and financial burden of experiments. This study investigated whether gait stability could be analyzed using only the COM-COP (Center of Mass-Center of Pressure) inclination angle connecting COM and COP. COM and COP coordinates were obtained from a motion analysis system for a total of 40 elderly and young subjects. The COM-COP inclination angle that changed in real time during level walking was then analyzed to obtain gait stability on each of sagittal and frontal planes using these coordinates. As a result, the gait symmetry index on the sagittal plane did not show a statistically significant difference between young and elderly subjects (First Step, p = 0.189; Second Step, p = 0.711). On the frontal plane, elderly subjects showed 0.39 degrees (p = 0.058) and 0.5 degree (p = 0.03) larger side-to-side sway angles in the first and second steps than young subjects, respectively. Gait stability can be analyzed using a more simplified experimental method with minimum amount of data in future gait analysis.

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Controlling the Fluid Induced Instability of a Supercritical CO₂ Compressor Supported by Magnetic Bearing: Sheng-He Jin, Jae-Eun Cha, Jee-Uk Chang, Sang-Hyun Choi, Hyeong-Joon Ahn; J. Korean Soc. Precis. Eng. 2020;37(10):737-742.
Published online October 1, 2020; DOI: https://doi.org/10.7736/JKSPE.020.049

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Since sCO₂ (Supercritical Carbon Dioxide) turbomachinery are generally small and operate at high rotational speed, the bearings remain a significant challenge to the design of the turbomachinery for the sCO₂ power cycles. However, a fluid induced instability similar to the oil whirl may occur even with the magnetic bearing under high pressure and high speed conditions of the sCO₂ turbomachinery. This paper presents experimental investigation on the instability of a sCO₂ compressor supported by the magnetic bearing. First, we introduce the sCO₂ compressor supported by the magnetic bearing. The procedure to guarantee the rotordynamic performance of the sCO₂ compressor supported by the magnetic bearing is provided. Then, the effects of the working condition such as the pressure and rotating speed on the fluid induced instability are investigated experimentally. Finally, a strategy to resolve the fluid-induced instability with conventional PID control is proposed and experimentally verified.

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Turbomachine Operation with Magnetic Bearings in Supercritical Carbon Dioxide Environment
Alexander Johannes Hacks, Dieter Brillert
International Journal of Turbomachinery, Propulsion and Power.2022; 7(2): 18. CrossRef
A Study on the Efficient Optimization of Controller for Magnetic Bearings Supporting Oil-Free Turbo-Chiller Compressor
Eunsang Kwon, Myounggyu Noh, Namsoo Lee, Seongki Baek, Young-Woo Park
Journal of the Korean Society for Precision Engineering.2022; 39(2): 123. CrossRef

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Experimental Research on Running Stability of Swing Motion Bogie System for a Freight Car: Jeong Hwan Choi, Hae Young Ji, Jin Kyu Park, Seung Gie Jeon; J. Korean Soc. Precis. Eng. 2020;37(5):321-330.
Published online May 1, 2020; DOI: https://doi.org/10.7736/JKSPE.019.161

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The swing motion bogie system for a freight car is more effective regarding the vibration damping effect than other freight car bogie systems while operating, and it is a bogie system that can travel up to 120 km/h despite being a freight car. Imported in 2006 in Korea and operated for more than 10 years in the domestic railway environment, the performance and maintenance efficiency have been proven compared to the existing welding bogies. As a result, the domestic demand will continue increasing in the future, but it is now dependent on overseas imports. In the long term, it is expected to cause problems such as loss of foreign currency and delay in procurement during maintenance. For this reason, development of the localization of the swing motion bogie system is underway, and it requires accurate performance analysis and validation of operating behavior characteristics because the bogie system is one of the main devices of the railway vehicles. Thus, in this study, we could confirm the suitability of the swing motion bogie system in the domestic operating environment based on the analysis of the operating behavior characteristics, the validation at the laboratory environment, and the operating test on the track.

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High-Stable RF-Frequency Generation Using a Microcontroller for Amplitude Modulation Based Absolute Distance Measurement: Yeongjin Yu, Joohyung Lee; J. Korean Soc. Precis. Eng. 2019;36(7):605-609.
Published online July 1, 2019; DOI: https://doi.org/10.7736/KSPE.2019.36.7.605

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In this paper, we describe high-stable RF-frequency generation using a low-cost 8-bit microcontroller for amplitudemodulation based distance measurement, which is one of the indispensable technologies for cost-effective Lidar application. The RF frequency generator using the microcontroller was implemented by externally referencing to an atomic clock and 8- bit timer/pulse width modulation (PWM) functions, which are embedded in a microcontroller. The microcontroller we used was ATmega128 of Microchip with 16 MHz clock and 8-bit timer, which generates the maximum frequency of up to 62.5 kHz, enabling 2.4-kilometer ranging without phase ambiguity. The stability of RF-frequency generated from the implemented system was evaluated in terms of Allan deviation using a commercial frequency counter. The stability indicated 10^-11 at 1-s averaging time and 10^-12 at 100 s averaging time, which represents a 1/10 degradation compared to the stability of the commercial function generator. Along with the stability evaluation, we interrogated frequency tunability, which extends a measurable range without phase ambiguity.

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Determination of the Gait Stability of the Lower-Limb Exoskeleton Robot Through the Stability Circle: Seung Hoon Hwang, Seung Chan Lee, Dong Bin Shin, Bum Soo Kim, Chang Soo Han; J. Korean Soc. Precis. Eng. 2019;36(6):537-542.
Published online June 1, 2019; DOI: https://doi.org/10.7736/KSPE.2019.36.6.537

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Patients with complete paralysis that only walk with the assistance of exoskeleton robots because they lost their ability to walk. However, robots do not allow the exoskeleton robot to grasp the current state before walking and change the walking pattern. A "Stability Circle Region" was proposed to determine the current state of the exoskeleton robot. The Stability Circle is an area that can determine the possibility of a fall situation before the next walk using the link parameters of the robot and the current center of gravity of the patients. This study verified the validity of "stability circle" by simulating the change in the center of mass. Simulation results can be used to determine the stability of walking depending on whether the position of the center of mass before the walking is included in the circle area.

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Design of Assistive Wearable System for Walking
Seong-Dae Choi, Sang-Hun Lee
Journal of the Korean Society of Manufacturing Process Engineers.2019; 18(12): 111. CrossRef

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The Development of Foldable Electric Wheelchair with Separable Power Module: Dae Jin Jang, Yong Cheol Kim, Shin Ki Kim, Je Cheong Ryu; J. Korean Soc. Precis. Eng. 2018;35(10):1007-1014.
Published online October 1, 2018; DOI: https://doi.org/10.7736/KSPE.2018.35.10.1007

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This study shows the 4 - Bar linkage design process and static/dynamic stability analysis of a foldable electric wheelchair that can be loaded into a vehicle for long-distance trips. Conventional foldable electric wheelchairs have been developed for indoor use because the safety of the disabled is not secure enough for outdoor use. However, the disabled have generally used foldable electric wheelchairs for outdoor use, potentially putting themselves in a dangerous situation. The body of a foldable electric wheelchair consists of a double 4 - Bar linkage system that shares one link. The architecture of the wheelchair’s four-bar linkage frame was synthesized using four finitely separated design positions. This simple method can design a planar four-bar mechanism through the use of four finitely separated poses (orientation and position). The power driving module includes a battery and controller, and can be separated to load into a car easily. An analysis of the tip-over measurement was performed using ADAMS and LifeMOD during a maneuver on the ground. by force-moment stability metric. Several elements, including the center of gravity position, rotational radius, and acceleration, were evaluated how to affect stability metric.

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A study on the formative usability testing for modular powered wheelchair
Jin Hong Kim, Yu Ri Kim, Mi Hyang Han, Soul Han, Eun hye Jeon, Eun Young Hwang, Jae Won Yang, Seon Yeong Lee, Gangpyo Lee
Disability and Rehabilitation: Assistive Technology.2025; 20(2): 452. CrossRef

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Analysis in the Change of Paraspinal Muscle Activities and Adjacent Disc Degeneration according to the Segmental Fusion: Hae Won Choi, Young Eun Kim; J. Korean Soc. Precis. Eng. 2018;35(7):721-727.
Published online July 1, 2018; DOI: https://doi.org/10.7736/KSPE.2018.35.7.721

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The incidence of adjacent segment degeneration (ASD) after lumbar spinal fusion have not been precisely verified. In the presence of mild degeneration in the proximal segment adjacent to the fused segment, selection of additional fusion is not agreed upon. Muscle activity change and ASD after fusion was analyzed with a developed three-dimensional finite element model of musculoskeletal system. The paraspinal muscle activities were calculated based on a hypothesis, the intervertebral disc was assumed to have a transducer function and the muscle is activated according to a sensor driven control mechanism to maintain the stability of the lumbar spine. Simulation was conducted for erect standing and 60° isometric forward flexed posture. Total muscle force produced in each deep muscle group was similar however activity of some muscle fascicles which inter-connected to the vertebrae above the fused segment showed increased value. In the presence of mild degeneration in the proximal adjacent segment, muscle activity across the degenerated segment was reduced. Despite changes in muscle activity, nucleus pressure at adjacent segment was increased in both cases. This change would eventually lead to the ASD.

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Chattering-Free Second Order Sliding Mode Based Finite-Time Control of a Robot Manipulator Considering Uncertainty and Disturbance: Yook Hyun Yoon, Jae Min You, Jahng Hyon Park; J. Korean Soc. Precis. Eng. 2018;35(4):421-426.
Published online April 1, 2018; DOI: https://doi.org/10.7736/KSPE.2018.35.4.421

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This paper presents a finite-time tracking control for a robot manipulator in the presence of a modeling uncertainty and an external disturbance. To solve the large chattering phenomenon that is caused by the high switching gain of the slidingmode control, a novel second-order sliding-mode controller that generates a continuous control input is designed with a robust differentiator. The finite-time stability of the closed-loop system is ensured using a constructive Lyapunov-stability analysis. Finally, a numerical simulation of the 2-Axis Pan-Tilt system is performed to verify the effectiveness of the proposed controller.

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Analysis of the Role of Thoracolumbar Fascia for Lumbar Spinal Stability: Hae Won Choi, Young Eun Kim; J. Korean Soc. Precis. Eng. 2017;34(11):823-828.
Published online November 1, 2017; DOI: https://doi.org/10.7736/KSPE.2017.34.11.823

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Spinal stability is controlled by two interrelated systems: the spinal column including ligaments and the muscular control system. In addition to these systems, the thoracolumbar fascia (TLF) also interacts with the muscular system to maintain the stability of the spine. The effects of the tensioning of TLF on the spinal stability was investigated using computational analysis. The stability of the spine was analyzed with a three-dimensional finite element model of musculoskeletal system including TLF. The paraspinal muscle activities were calculated based on a hypothesis: the intervertebral disc was assumed to have a transducer function and the muscle is activated according to a sensor driven control mechanism to maintain stability of the lumbar spine. Muscle forces were calculated in examining 40o isometric forward flexed and erect standing postures. As a result, the fascial tension induced a decrease in superficial muscle activity while maintaining the spinal stability.

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A Novel Wall Touch-Single Limb Stance Exercise for Dynamic Activation o f Gluteus Maximus - A Cross Sectional Study
Babina Rani, Shivam Sharma, Prerana Berwal, Ritu Shree, Mandeep S. Dhillon
Journal of Orthopaedics.2023; 41: 33. CrossRef
Analysis in the Change of Paraspinal Muscle Activities and Adjacent Disc Degeneration according to the Segmental Fusion
Hae Won Choi, Young Eun Kim
Journal of the Korean Society for Precision Engineering.2018; 35(7): 721. CrossRef

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Driving Stability Analysis of Shelter Vehicles Passing by Each Other: Jeongroh Yoon, Donghun Son, Euibong Jeong, Joon Kim, Inkab Jang; J. Korean Soc. Precis. Eng. 2017;34(11):781-787.
Published online November 1, 2017; DOI: https://doi.org/10.7736/KSPE.2017.34.11.781

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Tactical devices and equipment are usually loaded on a trailer vehicle within a shelter system. When the vehicle is moving fast and passing other vehicles, side panels of the shelter are deformed and tilted by pressure waves. Also, the vehicle is subjected to the effects of wind load and centrifugal force with the pressure waves at severe conditions. In this study, a theoretical analysis of overturn calculated by CFD (Computational Fluid Dynamics) and experiments is applied to the vehicle. Deformations of the side panel are measured for experimental validation of the CFD model. As a result, the safety factor of the driving stability of the vehicle is derived by theoretical analysis in the severe situation predicted by the validated CFD model.