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발걸림 상황에서의 보행패턴 : 무게중심의 위치에 따른 무의식적인 회복전략 선택
김정민(Jeongmin Kim),곽문규(Moonkyu Kwak),황동환(Dongwhan Hwang),정지욱(Jiuk Jung),우현수(Hyunsoo Woo),이용구(Yongkoo Lee) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
The objective of this study was to find out what made differences in unconscious selection of recovery strategy when tripping over. Seven subjects, who did not have any lower extremity musculoskeletal disorder within one year prior to the study, participated in this study. Eight infrared cameras and one force plate were used to analyze the gait patterns. A remotely controlled pop-up obstacle to randomly trip over subjects was installed within pathway in front of the force plate. As a result, three types of recovery strategy were observed immediately after tripping over. An elevating strategy of lifting the tripped foot, was grouped into type-A₁ and type-A₂ with respect to swing phase time, maximum height of lower extremity, joint angle and moment, and joint angular velocity; meanwhile, a lowering strategy in which the tripped-foot was unable to surmount the obstacle was grouped as type-B. These three types were categorized in accordance with the COM position. The relative position between the supporting-foot and the COM was found to significantly impact the unconscious selection of recovery strategy when tripping over.
발목형 로봇의족의 발걸림 위험 제어를 위한 갑작스런 충돌 상황에서의 보행패턴 분석
김정민(Jeongmin Kim),곽문규(Moonkyu Kwak),황동환(Dongwhan Hwang),정지욱(Jiuk Jung),우현수(Hyunsoo Woo),이용구(Yongkoo Lee) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
This study was performed to analyze human gait strategy of tripping over in order to control the robotic ankle prosthetics under amputees tripping over. The subjects were 7 men, who had no serious foot musculoskeletal disease within 1 years prior to study. When tripping over, we found out there were three types of patterns of tripping over, which were classified into type A, type B and type C according to the distance from the obstacle to supporting foot. The distinction between type A and type C was also related to the position of center of mass. A situation of higher risk occurred when center of mass was forward to the supporting foot. At the moment the ankle of tripped foot rapidly acted dorsiflexion. Authors recommend that when an accidental collision with an obstacle occurs during walking, tripped robotic foots ankle should act dorsiflexion immediately.
발걸림 상황에서의 보행패턴 : 무게중심의 위치에 따른 무의식적인 회복전략 선택
김정민(Jeongmin Kim),곽문규(Moonkyu Kwak),황동환(Dongwhan Hwang),정지욱(Jiuk Jung),우현수(Hyunsoo Woo),이용구(Yongkoo Lee) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
The objective of this study was to find out what made differences in unconscious selection of recovery strategy when tripping over. Seven subjects, who did not have any lower extremity musculoskeletal disorder within one year prior to the study, participated in this study. Eight infrared cameras and one force plate were used to analyze the gait patterns. A remotely controlled pop-up obstacle to randomly trip over subjects was installed within pathway in front of the force plate. As a result, three types of recovery strategy were observed immediately after tripping over. An elevating strategy of lifting the tripped foot, was grouped into type-A₁ and type-A₂ with respect to swing phase time, maximum height of lower extremity, joint angle and moment, and joint angular velocity; meanwhile, a lowering strategy in which the tripped-foot was unable to surmount the obstacle was grouped as type-B. These three types were categorized in accordance with the COM position. The relative position between the supporting-foot and the COM was found to significantly impact the unconscious selection of recovery strategy when tripping over.
자동변속기 클러치 윤활 및 냉각해석을 통한 오일 홀 최적화
김학기(Hakki Kim),송경(Kyoung Song),박재인(Jaein Park),황동환(Dongwhan Hwang),김현석(Hyunsuk Kim) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
The flow rate of the automatic transmission fluid (ATF) from a input shaft to the clutch plates have been simulated as a three-dimensional and transient-state using the free surface method of commercial CFD code STAR-CCM+. During the disengagement of the wet clutch plates, amount of heat energy dissipated by the lubricating oil that flow the nominal gap between the plates which have relative rotating speed. To supply the oil equally into the nominal clearances among the friction plates, a lay out of the lubrication passage hole configuration is very important. Since the hole configurations can be changed by the hole number, shape and the position at the hub, the optimization of the oil hole configuration is necessary. It is difficult to estimate the flow rate of the lubricating oil exactly at each part of the automatic transmission because of its structural complexity under rotating conditions. This paper suggest the method that can estimate the optimal oil hole configurations which affect the temperature of the plates by using 1D ATF oil circuit simulation and the numerical thermal analysis program “clutchtherm” with the 3D CFD results. From this result, we can obtain various information about the lubricating state at every part of the plates and can help our judgment of whether lubrication is sufficient.