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.

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.

수동 휠체어 추진 시 부하에 따른 상지 운동

황선홍(S. H. Hwang),김영호(Y. H. Kim),이희영(H. Y. Lee) 한국정밀공학회 2010 한국정밀공학회 학술발표대회 논문집 Vol.2010 No.5월

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

손가락 끝 힘 측정 시스템 개발 및 건강한 성인의 개별 손가락 끝 힘 분포

황지선(J. S. Hwang),황선홍(S. Hwang) 한국재활복지공학회 2021 한국재활복지공학회 학술대회논문집 Vol.2021 No.4

In this paper, we developed a fingertip force measurement system using force sensitive resistors (FSR) and evaluated the validity and reliability of the system. Moreover, we measured fingertip force distributions for healthy subjects when they gripped an elliptic object with their maximum effort. The systems root mean square error showed smaller than 0.06 for all five FSR sensors, and they showed good intra-class correlation coefficients and very small standard error measures less than 0.1. Mean-maximum fingertip forces for five fingers showed that 1st, 2nd, 3rd fingers have similar values with 1.3 kgf, and 4th and 5th fingers have 0.94 and 0.74 kgf respectively. We expect that this study results would be useful for rehabilitation diagnosis and therapy by comparison with those for spinal cord injury patients.

골프 스윙 시 경사면에 따른 지면 반력 분석에 관한 연구

문곤성,최희석,황선홍,김영호,Moon, G.S.,Choi, H.S.,Hwang, S.H.,Kim, Y.H. 대한의용생체공학회 2007 의공학회지 Vol.28 No.2

The purpose of this study is to determine the characteristics of ground reaction force(GRF) in golf swing for various slopes of flat lie and uphill lies of 5 and 10 degrees. Five right-handed professional golfers were selected for the experiment and the 7 iron club was used. We used four forceplates to measure GRF and synchronized with the three-dimensional motion analysis system. Results showed that slope did not affect the total time for golf swing, but the time until the impact had a tendency to slightly increase for the uphill lie(p<0.05). The medial-lateral GRF of the right foot increased toward the medial direction during back swing, but less increases were found with the angle of uphill lie(p<0.05). The GRF of the left foot increased rapidly toward the medial direction at the uncocking and the impact during down swing, but decreased with the increase in the angle of uphill lie(p<0.05). The anterior-posterior GRF of both feet showed almost the same for different slopes. With the slopes, the vertical GRF of the right foot increased, but the vertical GRF of left foot decreased(p<0.05). Uphill lies would have negative effect to provide the angular momentum during back swing, restricting pelvic and trunk rotations, and to provide the precise timing and strong power during down swing, limiting movements of body's center of mass. The present study could provide valuable information to quantitatively analyze the dynamics of golf swing. Further study would be required to understand detailed mechanism in golf swing under different conditions.

골프 스윙 시 경사도에 따른 지면 반력 변화에 관한 연구 : 오르막 경사를 중심으로

문곤성(G. S. Moon),최희석(H. S. Choi),황선홍(S. H. Hwang),김영호(Y. H. Kim) 한국정밀공학회 2006 한국정밀공학회 학술발표대회 논문집 Vol.2006 No.10월

건강한 노인과 파킨슨 환자의 정적 기립 자세에서 압력중심 궤적에 대한 정위검사 및 탈경향 변동분석

이재선(J. S. Ree),황선홍(S. Hwang) 한국재활복지공학회 2020 재활복지공학회논문지 Vol.14 No.1

본 연구는 압력중심(COP) 좌표를 이용하여 파킨슨 병 환자와 건강한 노인들의 정적기립 균형능력을 비교하고자 하였다. 파킨슨병 환자와 건강한 노인 각 13명이 4가지 검사 조건(딱딱한 바닥에서 눈을 뜨고 1, 눈을 감고 2, 균형패드 위 눈 뜨고 3, 균형패드 위 눈 감고 4)에서 정적기립 시 COP 좌표를 수집, 분석하여 전후(Rx), 내외(Ry)방향의 COP 동요, COP 총 이동거리(L), COP 동요면적(A), 탈경향 변동분석(DFA)을 통한 변동척도(α)를 계산하였다. 1~3번 조건에서 Rx, Ry, L, A는 모두 파킨슨 환자가 유의하게 큰 값을 보였다. 반면 균형패드 위에서는 시각 정보가 정상일 때는 파킨슨 환자의 내외 방향 α가 건강한 노인보다 컸고, 시각정보가 차단되었을 때는 파킨슨 환자의 전후 방향 α가 유의하게 낮은 값을 보였다. DFA 결과가 고유 수용성감각이 교란된 균형패드 위에서만 각 방향에서 집단 간 서로 다른 양상을 보인 것으로 미루어 파킨슨 병 환자는 일반 노인들과는 다른 고유수용성감각 통합의 기능의 변화가 있는 것으로 해석된다. 이러한 결과는 임상에서 노인군 균형능력 저하의 원인을 감별하는데 유용할 것으로 사료된다. 다만, 본 연구의 결과를 일반화하기 위해서는 더 많은 표본을 대상으로 한 연구가 추가되어야 할 것이다. The purpose of this study is to find quantitative scaling properties of the center of pressure(COP) trajectory by comparison between healthy and Parkinsonian people. Thirteen people with Parkinson’s disease (PD) and thirteen healthy elderly (HE) have participated in this study. Subjects were asked to stand quietly on a pressure mat with four different conditions – 1) eye open, 2) eye closed, 3) eye open on a balance pad, and 4) eye closed on a balance pad. The COP movements were recorded and analyzed for those conditions. Sway range in anterior-posterior (Rx) and medio-lateral (Ry) directions, a total length of the trajectory (L), and sway area (A) as well as scaling exponents (α) from DFA were calculated from measured data. All temporal behaviors of the COP (Rx, Ry, L, and A) from the PD were significantly larger than those of the HE in conditions 1, 2, 3. However, the PD showed different characteristics of α from those of the HE when the proprioception was distorted on the foam floor. The DFA scaling exponent might inform that the PD has differences to integrate proprioceptive signals than healthy elderly.

보행 장애인을 위한 능동형 보행훈련 시스템 개발 및 평가

황성재,태기식,강성재,김정윤,황선홍,김한일,박시운,김영호,Hwang, S.J.,Tae, K.S.,Kang, S.J.,Kim, J.Y.,Hwang, S.H.,Kim, H.I.,Park, S.W.,Kim, Y.H. 대한의용생체공학회 2007 의공학회지 Vol.28 No.2

Modem concepts of gait rehabilitation after stroke favor a task-specific repetitive approach. In practice, the required physical effort of the therapists limits the realization of this approach. Therefore, a mechanized gait trainer enabling nonambulatory patients to have the repetitive practice of a gait-like movement without overstraining therapists was constructed. In this study, we developed an active gait training system for patients with gait disorder. This system provides joint movements to patients who cannot carry out an independent gait. It provides a normal stance-swing ratio of 60:40 using an eccentric configuration of two gears. Joint motions of the knee and the ankle were evaluated with using the 3D motion analysis system and compared with the results from the multi-body dynamics simulation. In addition, clinical investigations were also performed for low stroke patients during the 6-week gait training. Results from the dynamics simulation showed that joint movements of the knee and the ankle were affected by the gear size, the step length and the length of the foot plate, except the radius of curvature of the foot guide plate. Also, the 6-week gait training revealed relevant improvements of the gait ability in all low subjects. Functional ambulation category levels of subjects after training were 2 in three patients and 1 in a patient. The developed active gait trainer seems feasible as an adjunctive tool in gait rehabilitation after stroke.