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"Hyungseok Lee"

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"Hyungseok Lee"

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Prediction of Falls Risk Using Toe Strength and Force Steadiness based on Deep Learning: A Preliminary Study
Jin Seon Kim, Seong Un Choi, Chang Yeop Keum, Jaehee Lee, Woong Ki Jang, Kwang Suk Lim, Hyungseok Lee, Byeong Hee Kim, Tejin Yoon
J. Korean Soc. Precis. Eng. 2023;40(7):519-526.
Published online July 1, 2023
DOI: https://doi.org/10.7736/JKSPE.023.050
Falls are common among older people. Age-related changes in toe strength and force steadiness may increase fall risk. This study aimed to evaluate the performance of a fall risk prediction model using toe strength and force steadiness data as input variables. Participants were four healthy adults (25.5±1.7 yrs). To indirectly reproduce physical conditions of older adults, an experiment was conducted by adding conditions for weight and fatigue increase. The maximal strength (MVIC) was measured for 5 s using a custom toe dynamometer. For force steadiness, toe flexion was measured for 10 s according to the target line, which was 40% of the MVIC. A one-leg-standing test was performed for 10 s with eyes-opened using a force plate. Deep learning experiments were performed with seven conditions using long short-term memory (LSTM) algorithms. Results of the deep learning model were randomly mixed and expressed through a confusion matrix. Results showed potential of the model"s fall risk prediction with force steadiness data as input variables. However, experiments were conducted on young adults. Additional experiments should be conducted on older adults to evaluate the predictive model.
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Stacked Artificial Muscle Actuator Based on Dielectric Elastomer
Kwangjun Ahn, Hyeok Yong Kwon, Daegyeong Kim, Hyungseok Lee, Nguyen Canh Toan, Jachoon Koo, Hyungpil Moon, Jae-do Nam, Hyouk Ryeol Choi
J. Korean Soc. Precis. Eng. 2011;28(11):1234-1241.
Published online November 1, 2011
In this work the potential, and the perspectives of the dielectric elastomer actuator are overviewed briefly. As an exemplary work, we introduce a novel contractile artificial muscle actuator based on Synthetic Elastomer(SE). SE is the name of new dielectric elastomer material we have developed and its synthesis procedures and evaluations are described in the first. The contractile artificial muscle actuator is made by stacking the actuator unit one by one along the in thickness direction and finished up by bonding the multi-stacked actuator. Its possibility for the robotic actuator is discussed and demonstrated via experiments.
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Phase Peak Ambiguity According to Illumination in White-Light Phase-Shifting Interferometry
Geehong Kim, HyungSeok Lee
J. Korean Soc. Precis. Eng. 2008;25(1):85-91.
Published online January 1, 2008
White light scanning interferometry has gotten a firm position in 3D surface profile measuring field. Recently, the LCD industry gave a chance for this technology to enter into real industry fields. It is known that white-light phase¬shifting algorithm give a best resolution compare to other algorithms, but there are some problems to be resolved. One of them is 300㎚ jump in height profile, called bat-wing effect. The main reason of this problem is an ambiguity of phase¬peak detection algorithm, and some solution has been proposed, but it didn't work perfectly. In this paper, I will show the cases when these effects are occurred, and these height discrepancies will be almost disappeared when broad-band illuminators are used.
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