• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1157-1160
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• 1996

Control of a biped robot which has compliant ankle joints is dealt in this paper. Simulated version of a human ankle joint is built using springs and mechanical constraints, which gives a flexibility of joint and compliance against the touching ground. The biped robot with compliant ankle joints proposed here gives a good contact between its sole and the ground and makes foot landing soft. As a result, installing force sensors for measuring the center of gravity of the biped becomes easier. A motor to drive an ankle joint is not needed which makes legs light. However, the control problem becomes more difficult because the torque of the ankle joint to put the biped in a desired walking gait cannot be provided from the compliant ankle joint. To solve this problem, we proposed a dynamic gait modification method by adjusting the position of a hip joint. Simulation results for the mathematical model of the SD-2 biped in the Ohio State University are given to show the validity of the proposed controller.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.301-303
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• 2001

This paper deals with the biped robot gait on changing the initial postures. Gait of a biped robot depends on the constraints of mechanical kinematics and initial posture. Also biped robot's dynamic walking stability is investigated by ZMP(Zero Moment Point). The path trajectory. with the knee joint bent like a human, is generated and applied with the above considerations. To decrease trajectory tracking error, in this paper, a new initial posture similar to bird's case is proposed and realized with the real robot.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.959-964
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• 1992

This study treats the method for kinematic modeling of the biped walking robot, for synthesizing various gait trajectories, and for calculating adequate values of the joint torque inside the stable region. To synthesize various and anthropomorphic walking easily, the gait trajectory is specified by a set of ten walking prameters, and the trunk motion equation is derived by the zero moment point and the gait trajectory. By distributing ground reaction force and moment reduced at the zero moment point to the both feet, the joint torque equation can be derived readily, and according to this equation, the joint torque to stable walking can be computed.

• Structural Engineering and Mechanics
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• v.54 no.5
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• pp.937-953
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• 2015

This paper investigates the load model for single footfall trace of human walking. A large amount of single person walking load tests were conducted using the three-dimensional gait analysis system. Based on the experimental data, Fourier series functions were adopted to model single footfall trace in three directions, i.e. along walking direction, direction perpendicular to the walking path and vertical direction. Function parameters such as trace duration time, number of Fourier series orders, dynamic load factors (DLFs) and phase angles were determined from the experimental records. Stochastic models were then suggested by treating walking rates, duration time and DLFs as independent random variables, whose probability density functions were obtained from experimental data. Simulation procedures using the stochastic models are presented with examples. The simulated single footfall traces are similar to the experimental records.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.536-539
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• 1997

This paper presents a three dimensional modeling and a trajectory generation for minimized impact walking of the biped robot. Inverse dynamic analysis and forward dynamic analysis are performed considering impact force between the foot and ground for determining the actuator capacity and for simulating the proposed biped walking robot. Double support phase walking is considered for close to human's with adding the kinematic constraints on the one of the single support phase.

• The Journal of Korean Physical Therapy
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• v.23 no.4
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• pp.37-44
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• 2011

Purpose: The aim of this study was to investigate the effects of an exercise program using a virtual reality game and a gait exercise program using a treadmill on % maximum voluntary isometric contraction (%MVIC) and static and dynamic balancing capabilities. Methods: A total of 26 elderly women were included in the study. 13 women were assigned to an exercise program using a virtual reality game, and 13 to a gait exercise program using a treadmill. The subjects performed the exercise for 40 min per session, three sessions per week, for eight weeks. Results: The %MVIC of the vastus medialis was significantly increased from $28.91{\pm}2.03%$ to $32.98{\pm}2.6%$ in the virtual reality game exercise group (p<0.00). The %MVIC of the vastus lateralis was significantly increased from $27.17{\pm}1.93%$ to $31.50{\pm}2.18%$ (p<0.00) in the gait exercise program group. The whole path length with both feet on the floor and eyes open was significantly decreased from $1570.92{\pm}820.6mm$ to $1343.62{\pm}242.41mm$ (p<0.00). The whole path length with both feet on the floor and eyes closed was significantly decreased from $1819.85{\pm}361.14mm$ to $1581.05{\pm}285.11mm$ (p<0.00). The length of a functional reach was significantly increased from $25.2{\pm}4.23cm$ to $27.68{\pm}4.04cm$ (p<0.00). Conclusion: The exercise program using a virtual reality game is effective for improving the %MVIC and static and dynamic balancing capabilities in elderly women aged 65 years and more.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.1
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• pp.75-89
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• 2019

PURPOSE: This study measured the impact of a 12-week fall-prevention exercise program on balance, ambulatory ability, lower limb strength, and psychosocial characteristics in older adults diagnosed with dementia. METHODS: The participants comprised 31 older adults (9 men, 22 women) diagnosed with Alzheimer's or vascular dementia at a long-term care hospital located in Gunsan City. A fall-prevention exercise program was provided to the experimental group, while the control group was only provided with instruction and materials related to the fall-prevention exercise program. The participants were evaluated before the intervention, 6 weeks after the intervention, and 12 weeks after the intervention on static and dynamic balance abilities (using Timed Up and Go test: TUG, Tinetti-balance scale, one-leg standing test: OLS), gait (Tinetti-balance scale, 6-minute walk test: 6MWT), lower limb strength (sit to stand test; STS), and psychosocial characteristics (Short Form 36 Health Survey-Korean version, Korean Mini-Mental State Exam). RESULTS: An independent samples t-test and repeated measures analysis of variance were used for the statistical analysis. There were statistically significant improvements after the intervention (p<.05) in dynamic balance abilities (TUG and OLS using the left foot), gait (6MWT), and lower limb strength (STS) for the experimental group, but not for the control group. No difference was seen in psychosocial characteristics. CONCLUSION: Older adults with dementia who participated in the fall-prevention exercise program showed significant improvements in their static and dynamic balance abilities, lower limb strength, and ambulatory ability after the intervention.

• Proceedings of the ESK Conference
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• 1993.04a
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• pp.1-9
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• 1993

A human gait study is required for the biomechanical design of running shoes. A tow-dimensional dynamic model was developed in order to analyze lower extremity kinematics and loadings at the right ankle, knee, and hip joints. The dynamic model consists of three segments, the upper leg, the lower leg, and the foot. Each segment was assumed to be a rigid body with one or two frictionless hinge joints. The lower extremity motion was assumed to be planar in the sagittal plane. A young male subject was involved in the gait test and his anthropometric data were measured for the calculation of segement mass and moment of inertia. The experimental data were obtained from three trials of walking at 1.2m/s. The foot-floor reaction data were measured from a Kistler force plate. The kinematic data were acquired using a three-dimensional motion measurement system (Expert Vision) with six markers, five of which were placed on the right lower extremity segments and the rest one was attached to the force plate. Based on the model and experimental data for the stance phase of the right foot, the calculated vertical forces reached up to 492, 540, and 561 N at the hip, knee, ankle joints, respectively. The flexion-extension moments reached up to 155, 119, and 33 Nm in magnitude at the corresponding joints.

• Physical Therapy Korea
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• v.20 no.1
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• pp.74-80
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• 2013

We evaluated whether group locomotor imagery training-combined knowledge of performance (KP) lead to improvements in gait function in community dwelling individuals with chronic stroke. Ten adults who had suffered a hemiparetic stroke at least 6 months earlier participated in group locomotor imagery training-combined KP for 5 weeks, twice per week, with 2 h intensive training. Dynamic gait index scores increased significantly after the group locomotor imagery training-combined KP. However, times for the timed up-and-go test did not improve significantly after the training. Group locomotor imagery training-combined KP may be a useful option for the relearning of gait performance for community dwelling individuals with chronic hemiparetic stroke.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.4 s.247
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• pp.435-441
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• 2006

The anterior cruciate ligament(ACL) is an important stabilizer of knee joint. The ACL injury of knee is common and a serious ACL injury leads to ligament reconstruction surgery. Gait analysis is essential to identify knee condition of patients who display abnormal gait. The purpose of this study is to evaluate and classify knee condition of ACL deficient patients using a nonlinear dynamic method. The nonlinear method focuses on understanding how variations in the gait pattern change over time. The experiments were carried out for 17 subjects(l2 healthy subjects and five subjects with unilateral deficiency) walking on a motorized treadmill for 100 seconds. Three dimensional kinematics of the lower extremity were collected by using four cameras and KWON 3D motion analysis system. The largest Lyapunov exponent calculated from knee joint flexion-extension time series was used to quantify knee stability. The results revealed the difference between healthy subjects and patients. The deficient knee was significantly unstable compared with the contralateral knee. This study suggests an evaluation scheme of the severity of injury and the level of recovery. The proposed Lyapunov exponent can be used in rehabilitation and diagnosis of recoverable patients.