Torque and Power Outputs on Different Subjects during Manual Wheelchair Propulsion under Different Conditions

황선홍,김승현,손종상,김영호 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.3

Manual wheelchair users are at a high risk of pain and injuries to the upper extremities due to mechanical inefficiency of wheelchair propulsion motion. The kinetic analysis of the upper extremities during manual wheelchair propulsion in various conditions needed to be investigated. We developed and calibrated a wheelchair dynamometer for measuring kinetic parameters during propulsion. We utilized the dynamometer to investigate and compare the propulsion torque and power values of experienced and novice users under four different conditions. Experienced wheelchair users generated lower torques with more power than novice users and reacted alertly and sensitively to changing conditions. We expect that these basic methods and results may help to quantitatively evaluate the mechanical efficiency of manual wheelchair propulsion.

대퇴신경 손상 환아의 보행분석 : 사례연구

황선홍,박선우,손종상,박정미,권성주,최익선,김영호,Hwang, S.H.,Park, S.W.,Son, J.S.,Park, J.M.,Kwon, S.J.,Choi, I.S.,Kim, Y.H. 대한의용생체공학회 2011 의공학회지 Vol.32 No.2

The femoral nerve innervates the quadriceps muscles and its dermatome supplies anteromedial thigh and medial foot. Paralysis of the quadriceps muscles due to the injury of the femoral nerve results in disability of the knee joint extension and loss of sensory of the thigh. A child could walk independently even though he had injured his femoral nerve severely due to the penetrating wound in the medial thigh. We measured and analyzed his gait performance in order to find the mechanisms that enabled him to walk independently. The child was eleven-year-old boy and he could not extend his knee voluntarily at all during a month after the injury. His gait analysis was performed five times (GA1~GA5) for sixteen months. His temporal-spatial parameters were not significantly different after the GA2 or GA3 test, and significant asymmetry was not observed except the single support time in GA1 results. The Lower limb joint angles in affected side had large differences in GA1 compared with the normal normative patterns. There were little knee joint flexion and extension motion during the stance phase in GA1 The maximum ankle plantar/dorsi flexion angles and the maximum knee extension angles were different from the normal values in the sound side. Asymmetries of the joint angles were analyzed by using the peak values. Significant asymmetries were found in GA1with seven parameters (ankle: peak planter flexion angle in stance phase, range of motion; ROM, knee: peak flexion angles during both stance and swing phase, ROM, hip: peak extension angle, ROM) while only two parameters (maximum hip extension angle and ROM of hip joint) had significant differences in GA5. The mid-stance valleys were not observed in both right and left sides of vertical ground reaction force (GRF) in the GA1, GA2. The loading response peak was far larger than the terminal stance peak of vertical ground reaction curve in the affected side of the GA3, GA4, GA5. The measured joint moment curves of the GA1, GA2, GA3 had large deviations and all of kinetic results had differences with the normal patterns. EMG signals described an absence of the rectus femoris muscle activity in the GA1 and GA2 (affected side). The EMG signals were detected in the GA3 and GA4 but their patterns were not normal yet, then their normal patterns were detected in the GA5. Through these following gait analysis of a child who had selective injuries on the knee extensor muscles, we could verify the actual functions of the knee extensor muscles during gait, and we also could observe his recovery and asymmetry with quantitative data during his rehabilitation.

편마비 환자의 보행시작 시 총 압력중심 변화 : 사전연구

황선홍,박선우,최희석,김영호,Hwang, S.H.,Park, S.W.,Choi, H.S.,Kim, Y.H. 대한의용생체공학회 2010 의공학회지 Vol.31 No.1

Gait initiation is a transitional process from the balanced upright standing to the beginning of steady-state walking. Dysbalanced gait initiation often causes stroke patients to fall. The net center of pressure, measured by two triaxial force plates from twenty healthy subjects and two stroke patients, was investigated to assess asymmetry of gait initiation in hemiparetic subjects. The time interval and distance of the net center of pressure(CoP) moved from the initiation point to the toe off(S1) and from the toe off to the initial contact(S2) were calculated during gait initiation of normal and stroke patients. When the patient with right hemiplegia(A) initiated his gait with right foot, the time interval and the distance of the net CoP in S1 and S2 were smaller than that of normal subjects' values. However, he initiated the gait with left foot(unaffected side) the time interval and the distance of net CoP in S1 were larger than normative values. Differently, the patient with left hemiplegia(B) has shown that larger time interval and distance in S1 and smaller time interval and distance in S2 in both sides. His asymmetry(with which side the gait initiated) was not significant. It is too early to conclude that these results could be general characteristics of the stroke patients because the variations were large and moreover, the level of motor recovery of the patients was different. However, it is expected that these trials could help to set up the strategy of the therapy for the rehabilitation or prevention of fall in stroke patients.

진동 레그 프레스를 이용한 근력운동의 효과

황선홍,조영근,손량희,김영호,김한성,임도형,Hwang, S.H.,Cho, Y.G.,Sohn, R.H.,Kim, Y.H.,Kim, H.S.,Lim, D.H. 대한의용생체공학회 2009 의공학회지 Vol.30 No.3

The purpose of this study was to investigate the biomechanical effects of an application of whole body vibration during strengthening exercise. Every participant performed four weeks exercise program using general leg-press versus vibrating leg-press. Participants did legpress exercise three sets of 25 repetitions with the load of 25 percent of 1RM during first week, three sets of 20 repetitions with 40 percent of 1RM during second week, three sets of 15 repetitions with 60 percents of 1RM during third week, and three sets of 15 repetitions with 80 percent of 1RM during last fourth week. The vibration(25Hz, 5mm) was applied only to the vibration exercise group. A three dimensional virtual lower extremity model for one of subject and virtual leg-press model were generated. The knee extensor muscle forces were analyzed using the virtual model and the knee joint torque(maximum extension torque) was measured using an isokinetic device. Calculated muscle forces were smaller in vibrating leg-press exercise than in general leg-press exercise. An increase of the maximum knee extension joint torque was 2.14 times larger approximately after the four week vibration leg-press exercise program was performed.

Upper Limb Joint Motion of Two Different User Groups During Manual Wheelchair Propulsion

황선홍,김승현,손종상,김영호,이진복 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.4

Manual wheelchair users have a high risk of injury to the upper extremities. Recent studies have focused on kinematic and kinetic analyses of manual wheelchair propulsion in order to understand the physical demands on wheelchair users. The purpose of this study was to investigate upper limb joint motion by using a motion capture system and a dynamometer with two different groups of wheelchair users propelling their wheelchairs at different speeds under different load conditions. The variations in the contact time, release time, and linear velocity of the experienced group were all larger than they were in the novice group. The propulsion angles of the experienced users were larger than those of the novices under all conditions. The variances in the propulsion force (both radial and tangential) of the experienced users were larger than those of the novices. The shoulder joint moment had the largest variance with the conditions, followed by the wrist joint moment and the elbow joint moment. The variance of the maximum shoulder joint moment was over four times the variance of the maximum wrist joint moment and eight times the maximum elbow joint moment. The maximum joint moments increased significantly as the speed and load increased in both groups. Quick and significant manipulation ability based on environmental changes is considered an important factor in efficient propulsion. This efficiency was confirmed from the propulsion power results. Sophisticated strategies for efficient manual wheelchair propulsion could be understood by observation of the physical responses of each upper limb joint to changes in load and speed. We expect that the findings of this study will be utilized for designing a rehabilitation program to reduce injuries.

2015 AG Plenary in Perth

황선홍 전략물자관리원 2015 전략물자 focus Vol.- No.12

수동 휠체어 추진 속도에 따른 상지 관절 생체역학적 영향 분석

황선홍 대한의용생체공학회 2022 의공학회지 Vol.43 No.4

It is known that chronic pain and injury of upper limb joint tissue in manual wheelchair users is usually caused by muscle imbalance, and the propulsion speed is reported to increase this muscle imbalance. In this study, kinematic variables, electromyography, and ultrasonographic images of the upper limb were measured and analyzed at two different propulsion speeds to provide a quantitative basis for the risk of upper extremity joint injury. Eleven patients with spinal cord injury for the experimental group (GE) and 27 healthy adults for the control group (GC) par- ticipated in this study. Joint angles and electromyography were measured while subjects performed self-selected com- fortable and fast-speed wheelchair propulsion. Ultrasound images were recorded before and after each propulsion task to measure the acromiohumeral distance (AHD). The range of motion of the shoulder (14.35 deg in GE; 20.24 deg in GC) and elbow (5.25 deg in GE; 2.57 deg in GC) joints were significantly decreased (p<0.001). Muscle activation levels of the anterior deltoid, posterior deltoid, biceps brachii, and triceps brachii increased at fast propulsion. Spe- cifically, triceps brachii showed a significant increase in muscle activation at fast propulsion. AHD decreased at fast propulsion. Moreover, the AHD of GE was already narrowed by about 60% compared to the GC from the pre-tests. Increased load on wheelchair propulsion, such as fast propulsion, is considered to cause upper limb joint impingement and soft tissue injury due to overuse of the extensor muscles in a narrow joint space. It is expected that the results of this study can be a quantitative and objective basis for training and rehabilitation for manual wheelchair users to prevent joint pain and damage.

근속직원 소회

황선홍,조재일,채수홍,김소연,구재림,진종열,이경령,김현배,홍초롬,송민정 전략물자관리원 2017 전략물자 focus Vol.- No.16

과거와 미래 그 교차점에서 기적을 읽다

황선홍 전략물자관리원 2014 전략물자 focus Vol.- No.10

수동 휠체어 추진 중 방향전환 시 휠체어 추진 속도와 추진력과의 관계

황선홍(S. Hwang),Yen-Sheng Lin,Alicia M Koontz 한국재활복지공학회 2014 한국재활복지공학회 학술대회논문집 Vol.2014 No.11