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"Won Jae Lee"

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"Won Jae Lee"

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Correlation Analysis between Clinical Rating Scales and Inertial Signal Features in Parkinson’s Disease Patients
Tae Hee Kim, Ha Eun Jo, Hui Woo Choi, Pyoung-Hwa Choi, Won Jae Lee, Hee Seung Yang, Woo Sub Sim
J. Korean Soc. Precis. Eng. 2023;40(7):553-561.
Published online July 1, 2023
DOI: https://doi.org/10.7736/JKSPE.022.149
In this study, the Inertial Measurement Unit (IMU) signals and clinical evaluation scales for Parkinson"s disease were correlated. The study included 16 patients diagnosed with Parkinson"s disease. Each subject was evaluated based on Korean Mini-Mental State Examination (KMMSE), Unified Parkinson"s Disease Rating Scale (UPDRS) part 3, New Freezing of Gait Questionnaire (NFOGQ) parts 2 & 3, and Hoehn & Yahr Scale (H&Y). All subjects performed the Time Up and Go test by attaching IMU sensors to both ankles and torso. Based on the tilting angle of torso and the time of first step, the freezing and non-freezing windows were determined. Seven IMU features involving the ankle signals were calculated in the specific window. Spearman’s correlation analysis of clinical evaluation scales was performed. As a result, the freezing index and power of locomotion band (0.3-3 Hz) were recommended to determine UPDRS part 3. Also, the intensity of the locomotion band facilitated evaluation of NFOGQ part 3 regardless of freezing of gait.
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The Effects of Grid Shape on Flexibility and Durability of Flexible Transparent Metal Grid Films
Oh Young Kwon, Yo Sep Lee, Won Jae Lee, Young Moon Jang, Sung-Hoon Choa
J. Korean Soc. Precis. Eng. 2018;35(5):551-559.
Published online May 1, 2018
DOI: https://doi.org/10.7736/KSPE.2018.35.5.551
Recently, the metal grid electrode drew attention as a flexible transparent conductive electrode for touch screen panels. In metal grid electrodes, various shapes of grid patterns were used to avoid the moiré phenomenon. In this study, we investigated the effects of the metal grid shapes - such as the honeycomb, diamond, and square - on the flexibility and durability of the metal grid film using an experimental and numerical analysis. The flexibility of the metal grid film was evaluated via the following: bending, cyclic bending fatigue and stretching tests; it was compared with the numerical stress analysis. In the bending test, the resistance of the honeycomb grid sample increased by 10% at a bending radius of 10 mm. On the other hand, the diamond grid showed almost no change in resistance up to a bending radius of 6 mm. When the substrate was stretched to 5%, many cracks appeared on the surface of the honeycomb pattern sample. On the other hand, no cracks were found in the diamond pattern sample. Therefore, the diamond pattern exhibited superior flexibility and durability to the honeycomb pattern. The numerical stress analysis also showed that the honeycomb pattern had the highest stress and the diamond pattern had the lowest stress during bending and stretching, which corresponded with the experimental results.
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Performance Investigation of Rotary Discharge Machine by Analytical Method
Yeon Ho Jeong, Dae Man Jung, Kwon Jae Lee, Young Tae Cho, Yoon Gyo Jung
J. Korean Soc. Precis. Eng. 2016;33(12):965-970.
Published online December 1, 2016
Fuel used in the steel metallurgy industry is stored in huge stage systems called SILO. Fuel is released by RDM (Rotary Discharge Machine), at the place of utilization. RDM is located in the Silo, and is constituted of a main frame, driving part, discharging part and control part. RDM is combined to a direct motion on the rail in tunnel, having a rotary motion enabled by a motor. In this paper, we calculate the theoretical discharging capacity of RDM to confirm the correlation between design element and discharging capacity of RDM. Also, through structure analysis, we confirm the vulnerable point of RDM when it discharges the storage materials. We hope to apply these results to design a more efficient RDM.
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Development of Multi-functional Centerless Grinding System with 600 mm Wide Grinding Wheels
Jung Soo Oh, Chang Rae Cho, Tsukishima Hidehiro, Soon Joo Cho, Chung Hong Park, Jeong Seok Oh, In Bum Whang, Won Jae Lee, Seok Il Kim
J. Korean Soc. Precis. Eng. 2013;30(11):1129-1137.
Published online November 1, 2013
We report a centerless grinding machine which can perform multi-function with 600 mm wide grinding wheels. By increasing manufacturing area, long workpiece such as camshaft and steering shaft, is allowed to grind more quickly, compared with cylindrical grinding system. In this paper, the design of centerless grinding machine puts emphasis on symmetry to exploit the thermal stability. Results of finite element analysis shows that the difference of the structural deflection in the front and rear guideways is less than 1.5 μm due to symmetric design. The difference is less than 3.0 μm, even though the thermal deformation is considered. According to the performance evaluation, the radial error motion of the G/W spindle, which is measured by applying Donaldson Ball Reversal, is about 1.1 μm. The yaw error of the G/W slide is improved from 2.1 arcsec to 0.5 arcsec by readjusting the slide preload and ball screw.
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