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Lee, Jinkyu,Song, Yongnam,Shin, Choongsoo S. Elsevier 2018 GAIT AND POSTURE Vol.62 No.-
<P><B>Abstract</B></P> <P><B>Background</B></P> <P>During landing, the ankle angle at initial contact (IC) exhibits relatively wide individual variation compared to the knee and hip angles. However, little is known about the effect of different IC ankle angles on energy dissipation.</P> <P><B>Research question</B></P> <P>The purpose of this study was to investigate the relationship between individual ankle angles at IC and energy dissipation in the lower extremity joints.</P> <P><B>Methods</B></P> <P>Twenty-seven adults performed single-leg landings from a 0.3-m height. Kinetics and kinematics of the lower extremity joints were measured. The relationship between ankle angles at IC and negative work, range of motion, the time to peak ground reaction force, and peak loading rate were analyzed.</P> <P><B>Results</B></P> <P>The ankle angle at IC was positively correlated with ankle negative work (r = 0.80, R<SUP>2</SUP> = 0.64, <I>p <</I> 0.001) and the contribution of the ankle to total (ankle, knee and hip joint) negative work (r = 0.84, R<SUP>2</SUP> = 0.70, p < 0.001), but the ankle angle was negatively correlated with hip negative work (r = −0.46, R<SUP>2</SUP> = 0.21, <I>p</I> = 0.01) and the contribution of the hip to total negative work (r = −0.61, R<SUP>2</SUP> = 0.37, <I>p <</I> 0.001). The knee negative work and the contribution of the knee to total negative work were not correlated with the ankle angle at IC. The ankle angle at IC was positively correlated with total negative work (r = 0.50, R<SUP>2</SUP> = 0.25, <I>p < </I>0.01) and negatively correlated with the peak loading rate (r = −0.76, R<SUP>2</SUP> = 0.57, <I>p </I>< 0.001).</P> <P><B>Significance</B></P> <P>These results indicated that landing mechanics changed as the ankle angle at IC increased, such that the ankle energy dissipation increased and redistributed the energy dissipation in the ankle and hip joints. Further, these results suggest that increased ankle energy dissipation with a higher IC plantar flexion angle may be a potential landing technique for reducing the risk of injury to the anterior cruciate ligament and hip musculature.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ankle angle at initial contact (IC) alter energy dissipation of lower limb joints. </LI> <LI> Higher plantar flexion at IC increases ankle energy dissipation during landing. </LI> <LI> Higher plantar flexion at IC decreases hip energy dissipation during landing. </LI> <LI> Higher plantar flexion at IC decreases peak loading (GRF) rates. </LI> <LI> Higher plantar flexion at IC may reduce injury risk to the ACL and hip musculature. </LI> </UL> </P>
안일철(Ilchul Ahn),박용남(Yongnam Park),송태헌(Taehun Song) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
The Ultra-High Voltage (UHV) Circuit Breaker (CB) is a protective device that applies power to the power system through close - open operations and ensures the stability of the system from breaking fault currents caused by ground fault, shortcircuit, and other accidents. During close - open operation, the circuit breaker operates at high speed and generates a large dynamic force. Also, it is important to accurately evaluate the dynamic characteristics at the design stage because the dynamic characteristics have a great influence on the breaking performance. However, it is difficult to analyze exactly the dynamic characteristics due to the multi-physics condition in which the drive part of the UHV circuit breaker works in combination with mechanisms and fluid-elements. In this study, a co-simulation model of 1D system analysis program was developed based on 3D multi-body dynamics analysis program in order to obtain more accurate results for dynamic characteristics analysis of the drive part of UHV circuit breaker. Using this technique, the dynamic characteristics of UHV circuit breaker products were analyzed and the accuracy was verified.
안일철(Ilchul Ahn),박용남(Yongnam Park),송태헌(Taehun Song) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
The Ultra-High Voltage (UHV) Circuit Breaker (CB) is a protective device that applies power to the power system through close - open operations and ensures the stability of the system from breaking fault currents caused by ground fault, shortcircuit, and other accidents. During close - open operation, the circuit breaker operates at high speed and generates a large dynamic force. Also, it is important to accurately evaluate the dynamic characteristics at the design stage because the dynamic characteristics have a great influence on the breaking performance. However, it is difficult to analyze exactly the dynamic characteristics due to the multi-physics condition in which the drive part of the UHV circuit breaker works in combination with mechanisms and fluid-elements. In this study, a co-simulation model of 1D system analysis program was developed based on 3D multi-body dynamics analysis program in order to obtain more accurate results for dynamic characteristics analysis of the drive part of UHV circuit breaker. Using this technique, the dynamic characteristics of UHV circuit breaker products were analyzed and the accuracy was verified.
김성옥(Sungok Kim),박상욱(Sangwook Park),신용남(Yongnam Shin),송주태(Jootae Song) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
A study on LPi fuel pump controller was analyzed the main failure mode by the accelerated stress test and presented predicting life of failure mode by the accelerated life test. According to the results of accelerated stress test, the failure of LPi fuel pump controller happened Capacitor failure due to the high temperature. And the failure mechanism of LPi fuel pump controller using the x-ray scanning system appeared to be electrolyte leak and dry out of capacitor. According to the results of accelerated life test for main failure, the life of product failure was predicated at each of temperature level and confirmed the reproducibility. The final results are follows; ⅰ) Experiment is designed by Arrhenius model. ⅱ) The failure data from the accelerated life test was reviewed Suitability and verified Acceleration of distribution of life. ⅲ) shape parameter, activation energy and characteristic life were suggested.