• 한국응용과학기술학회지
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• 제35권1호
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• pp.55-61
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• 2018

The purpose of this study was to analyze the biomechanical differences of lower extremity joints of the frontal plane during sidestep cutting in male and female Judo athletes. In the knee and hip joint, the female group showed a smaller angle than the male group at the time of IC(initial contact). But peak knee joint adduction moment of female group was greater than male group(p<.05). Therefore, female Judo athletes were more likely to injure their knees at the point where their initial foot contacted the ground than male athletes during sidestep cutting.

• 한국운동역학회지
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• 제23권1호
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• pp.85-90
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• 2013

Efficient gait is compensate for a lack of exercise, but the wrong walking can cause disease that joints, muscles, brain and body structure(Scott & Winter, 1990). Also many researchers has been studied gait of positive mechanism using analytical methods kinetic, kinematic. This study is to identify nature of knee adduction moment, depending on different foot progression angle and the movement of rotation of pelvis and body. Health study subject conducted intended walking with three different angles. The subjects of this study classified three types of walking; walk erect, pigeon-toed walk and an out-toed gait. Ten university students of K without previous operation and disease record selected for this study. For accuracy of this study, three types of walking carried out five times with 3D image analysis and using analysis of ground reaction force to analyze nature of knee adduction moment and the movement of rotation of pelvis and body. Firstly, the HC(heel contact) section value of intended walk erect, pigeon-toed walk and an out-toed gait was not shown statistically significant difference but TO(toe off) section value was shown that the pigeon-toed walk statistically significant. The value of pigeon-toed walk was smallest knee adduction moment(p< 0.005). Secondly, X axis was the change of rotation movement body and pelvis when walk erect, pigeon-toed walk and an out-toed gait. Shown statistically Y axis was not shown statistically significant but Z axis statistically significant(p<0.05). These result show the significant differences on TO section when walking moment reaches HC, it decides the walking types and rotates the foot.

• 제어로봇시스템학회논문지
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• 제12권9호
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• pp.926-934
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• 2006

This paper proposes intelligent control of a virtual walking machine that can generate infinite floor for various surfaces and can provide proprioceptive feedback of walking to a user. This machine allows users to participate in a life-like walking experience in virtual environments with various terrains. The controller of the machine is implemented hierarchically, at low-level for robust actuator control, at mid-level fur platform control to compensate the external forces by foot contact, and at high-level control for generating walking trajectory. The high level controller is suggested to generate continuous walking on an infinite floor for various terrains. For the high level control, each independent platform follows a man foot during the swing phase, while the other platform moves back during single stance phase. During double limb support, two platforms manipulate neutral positions to compensate the offset errors generated by velocity changes. This control can, therefore, satisfy natural walking conditions in any direction. Transition phase between the swing and the stance phases is detected by using simple switch sensor system, while human foot motions are sensed by careful calibration with a magnetic motion tracker attached to the shoe. Experimental results of walking simulations at level ground, slope, and stairs, show that with the proposed machine, a general person can walk naturally on various terrains with safety and without any considerable disturbances. This interface can be applied to various areas such as VR navigations, rehabilitation, and gait analysis.

• 한국운동역학회지
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• 제25권4호
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• pp.489-498
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• 2015

Objective : The purpose of this study was to analyze the effects of the windlass mechanism in trail-walking shoe prototypes that can effectively support arches. A study of these effects should help with the development of a first-rate trail-walking shoe development guide for the distribution of quality information to consumers. Methods : The subjects were ten adult males who volunteered to participate in the study. Shoes from three companies, which will be referred to as Company S (Type A), Company M (Type B), and Company P (Type C), were selected for the experiment. The subjects wore these shoes and walked at a speed of 4.2 km/h, and as they tested each shoe, the contact area, maximum pressure average, and surface force were all measured. Results : Shoe Type A showed a contact area of $148.78{\pm}4.31cm^2$, Type B showed an area of $145.74{\pm}4.1cm^2$, and Type C showed an area of $143.37{\pm}4.57cm^2$ (p<.01). Shoe Type A demonstrated a maximum average pressure of $80.80{\pm}9.92kPa$, Type B an average of $85.72{\pm}11.01kPa$, and Type C an average of $89.12{\pm}10.88bkPa$ (p<.05). Shoe Type A showed a ground reaction force of $1.13{\pm}0.06%BW$, Type B a force of $1.16{\pm}0.04%BW$, and Type C a force of $1.16{\pm}0.03%BW$ (p<.05). Conclusion : The Type A trail-walking shoe, which was designed with a wide arch from the center of the forefoot to the front of the rearfoot showed excellent performance, however, more development and analysis of the windlass mechanism for a variety of arch structures is still necessary.

• 한국운동역학회지
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• 제18권1호
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• pp.159-168
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• 2008

본 연구는 피겨스케이팅의 여자국가대표 선수 4명으로부터 고난도 스핀기술인 FSS과 FCS동작을 분석하였다. 이를 위하여 자세유형에 따른 스핀동작 간 족저압력변인 접지면적(CA), 최대힘(MF), 최대압력(PP) 그리고 인체무게중심(COG)에 의한 발바닥 9개 영역을 중심으로 압력변화를 고찰하였다. 본 회전구간에서 두 스핀기술 간 접지면적이 17.2%의 차이로 스핀축이 한 곳에 보다 잘 집중된 경우는 FCS인것으로 나타났다. 최대힘에서 FSS는 97%BW, FCS는 143%BW로서 20% 높았으며, 최대압력 또한 FCS가 FSS보다 20% 높은 수치를 보였다. 이러한 결과는 인체무게중심선과 압력중심점과의 상호관계로부터 FSS의 압력중심점이 인체무게중심선보다 발바닥 후면, 반대로 FCS는 발바닥 앞면에 위치하는 자세패턴에 의한 기능적 차이로 분석되었다. 위의 결과로부터 FCS가 상대적으로 FSS보다 스핀기술 시 높은 인체중심과 하지말단을 이용한 큰 회전반경으로부터 스핀속도를 보다 잘 통제하는 운동구조로 고찰되었다.

• 대한족부족관절학회지
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• 제8권2호
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• pp.117-120
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• 2004

저자에 의해 개선된 변형 Mau 절골술은 우수한 교정력과 견고한 고정이 가능하면서도 술기가 간단하고 중족골두의 상하 전위가 없고 조기 보행이 가능한 안전한 방법이라 할 수 있었다. 따라서 향후 장기 추시가 필요하긴 하지만 중족골간각이 큰 중증의 무지외반증에서 추천할만한 좋은 방법으로 사료된다.

• 대한기계학회논문집A
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• 제24권6호
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• pp.1513-1519
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• 2000

This paper proposes a hybrid control method of using impedance control and the computed-torque control for biped robot locomotion. Computed torque control is used for supporting (constrained) leg. For the free leg, the impedance control is used, where different values of impedance parameters are used depending on the gait phase of the biped robot. To reduce the magnitude of an impact and guarantee a stable footing when a foot contacts with the ground, this paper proposes to increase the damping of the leg drastically and to modify the reference trajectory of the leg. Computer simulations with a 3 -dof environment model for which a combination of a nonlinear and a linear compliant models is used, show that the proposed controller is superior to the computed-torque controllers in reducing impacts and stabilizing the footing.

• 대한인간공학회지
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• 제27권3호
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• pp.93-101
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• 2008

Wedged soles and rocker soles are widespread shoe designs used to prevent the disorders and reduce the pain of the lower extremity caused by arthritis or diabetic feet. In this study, the effect of a shoe with a laterally wedged sole and a rocker sole simultaneously was analyzed on the kinematics and kinetics of the ankle joint during normal walking. Eight male participants without a history of lower extremity disorders were recruited. Each participant performed twenty walking cycles for each of three walking conditions: bare foot, wearing normal shoes and wearing shoes with laterally wedged rocker soles. The differences between the three walking conditions were statistically investigated including spatio-temporal variables, angular displacements, joint moments and ground reaction forces. The results showed that the laterally wedged rocker sole decreased the sagittal variation of angular displacements as well as the frontal/sagittal average moment on the ankle joints compared to the flat sole. In addition, the rate of angular displacements and loading decreased during the heel contact phase.

• 대한기계학회논문집A
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• 제24권4호
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• pp.1007-1015
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• 2000

This paper proposes an adaptive trajectory generation strategy of using on-line ZMP information and an impedance control method for biped robots. Since robots experience various disturbances during their locomotion, their walking mechanism should have the robustness against those disturbances, which requires an on-line adaptation capability. In this context, an on-line trajectory planner is proposed to compensate the required moment for recovering stability. The ZMP equation and sensed ZMP information are used in this trajectory generation strategy. In order to control a biped robot to be able to walk stably, its controller should guarantee stable footing at the moment of feet contacts with the ground as well as maintaining good trajectory tracking performance. Otherwise, the stability of robot will be significantly compromised. To reduce the magnitude of an impact and guarantee a stable footing when a foot contacts with the ground, this paper. proposes to increase the damping of the leg drastically and to modify the reference trajectory of the leg. In the proposed control scheme, the constrained leg is controlled by impedance control using the impedance model with respect to the base link. Computer simulations performed with a 3-dof environment model that consists of combination of a nonlinear and linear compliant contact model show that the proposed controller performs well and that it has robustness against unknown uneven surface. Moreover, the biped robot with the proposed trajectory generator can walk even when it is pushed with a certain amount of external force.

• 한국운동역학회지
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• 제21권1호
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• pp.31-38
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• 2011

This study aimed to determine the effects of the blockage of visual feedback on joint dynamics of the lower extremity. Fifteen healthy male subjects(age: $24.1{\pm}2.3\;yr$, height: $178.7{\pm}5.2\;cm$, weight: $73.6{\pm}6.6\;kg$) participated in this study. Each subject performed single-legged landing from a 45 cm-platform with the eyes open or closed. During the landing performance, three-dimensional kinematics of the lower extremity and ground reaction force(GRF) were recorded using a 8 infrared camera motion analysis system (Vicon MX-F20, Oxford Metric Ltd, Oxford, UK) with a force platform(ORG-6, AMTI, Watertown, MA). The results showed that at 50 ms prior to foot contact and at the time of foot contact, ankle plantar-flexion angle was smaller(p<.05) but the knee joint valgus and the hip flexion angles were greater with the eyes closed as compared to with the eyes open(p<.05). An increase in anterior GRF was observed during single-legged landing with the eyes closed as compared to with the eyes open(p<.05). Time to peak GRF in the medial, vertical and posterior directions occurred significantly earlier when the eyes were closed as compared to when the eyes were open(p<.05). Landing with the eyes closed resulted in a higher peak vertical loading rate(p<.05). In addition, the shock-absorbing power decreased at the ankle joint(p<.05) but increased at the hip joints when landing with the eyes closed(p<.05). When the eyes were closed, landing could be characterized by a less plantarflexed ankle joint and more flexed hip joint, with a faster time to peak GRF. These results imply that subjects are able to adapt the control of landing to different feedback conditions. Therefore, we suggest that training programs be introduced to reduce these injury risk factors.