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한국 고령자의 일상생활 중 다양한 높이에서의 STS(sit-to-stand) 시 관절운동 특성 및 근길이 변화 분석
황성재,손종상,김정윤,김현동,임도형,김영호,Hwang, S.J.,Son, J.S.,Kim, J.Y.,Kim, H.D.,Lim, D.H.,Kim, Y.H. 대한의용생체공학회 2008 의공학회지 Vol.29 No.6
Sit to stand(STS) movement is one of the most common activity in daily life. In addition, Korean traditionally stand up from various sitting heights in one's daily life compared to other foreigners. As Korea enter rapidly to the aging society, needs of the elderly's independent life are increasing. Therefore the importance of research about the analysis of elderly's activity in daily life is rapidly increasing. In this study, we analyzed joint movements and changes of muscle length during STS(sit-to-stand) at various sitting heights(table seat, bath seat, bottom) in the Korean elderly's daily life by using the motion analysis and musculoskeletal modeling. Ten Korean elderly and young were participated in this experiment. Three heights of sitting posture which could represent typical sitting in Korean daily life were chosen as table seat(42cm), bath seat(21cm) and bottom(0cm). As the results, the elderly showed both smaller knee/hip flexion and larger trunk flexion relatively in comparison to the young during table seat STS. The elderly also showed larger dorsiflexion and smaller ROM of knee, hip, trunk compared to the young during bath seat STS. Additionally, the elderly showed larger plantarflexion, hip flexion, smaller knee flexion and trunk flexion during the first half of bottom STS and larger knee flexion, hip flexion and trunk flexion during the second half of bottom STS. In addition, we could know contraction and relaxation characters of major muscles in lower limb during various STS through the analysis of changes in muscle length by musculoskeltal modeling.
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.
당뇨발 환자의 보행 시 발바닥 전단응력 및 압력분포 분석
황성재(S. J. Hwang),박선우(S. W. Park),김영호(Y. H. Kim) 한국정밀공학회 2005 한국정밀공학회 학술발표대회 논문집 Vol.2005 No.10월
In this study, we analyzed the plantar shear stress and pressure of diabetic foot patients during walking by using in-shoe local shear force and plantar pressure measurement system. Twelve normal subjects and three diabetic foot patients with diabetic neuropathy in lateral heel were participated in this study. The center of pressure in diabetic foot patients moved more medially and directed toward 1st, 2nd metatarsal heads and hallux during late stance period, making pressure at the medial heel and 2nd metatarsal head significantly higher than in the normal. Shear stress at the heel were changed significantly in early stance and the magnitude of shear stresses in each metatarsal head were also changed. Further studies would be very helpful to design foot orthoses in patients with diabetic neuropathy or other diseases.
근육 파라미터 최적화를 통한 발목관절 모멘트 추정 모델 개발 및 평가
손종상,황성재,이진섭,김영호,Son, J.,Hwang, S.,Lee, J.,Kim, Y.H. 대한의용생체공학회 2010 의공학회지 Vol.31 No.4
Estimation of muscle forces is important in biomechanics, therefore many researchers have tried to build a muscle model. Recently, optimization techniques for adjusting muscle parameters, i.e. EMG-driven model, have been used to estimate muscle forces and predict joint moments. In this study, an EMG-driven model based on the previous studies has been developed and isometric and isokinetic contraction movements were evaluated to validate the developed model. One healthy male participated in this study. The dynamometer tasks were performed for maximum voluntary isometric contractions (MVIC) for ankle dorsi/plantarflexors, isokinetic contraction at both $30^{\circ}/s$ and $60^{\circ}/s$. EMGs were recorded from the tibialis anterior, gastrocnemius medialis, gastrocnemius lateralis and soleus muscles at the sampling rate of 1000 Hz. The MVIC trial was used to customize the EMG-driven model to the specific subject. Once the subject's own model was developed, the model was used to predict the ankle joint moment for the other two dynamic movements. When no optimization was applied to characterize the muscle parameters, weak correlations were observed between the model prediction and the measured joint moment with large RMS error over 100% (r = 0.468 (123%) and r = 0.060 (159%) in $30^{\circ}/s$ and $60^{\circ}/s$ dynamic movements, respectively). However, once optimization was applied to adjust the muscle parameters, the predicted joint moment was highly similar to the measured joint moment with relatively small RMS error below 40% (r = 0.955 (21%) and r = 0.819 (36%) and in $30^{\circ}/s$ and $60^{\circ}/s$ dynamic movements, respectively). We expect that our EMG-driven model will be employed in our future efforts to estimate muscle forces of the elderly.
명성식(S. S. Myeong),금영광(Y. G. Keum),황성재(S. J Hwang),김한성(H. S. Kim),김영호(Y. H. Kim) 한국정밀공학회 2004 한국정밀공학회 학술발표대회 논문집 Vol.2004 No.10월
Numerous studies have been performed to analyze various phenomena of human"s walking, gait. In the present study, unrecognized walking and recognized walking were analyzed by three dimensional motion capture system(VICON motion system Ltd., England) and simulated by computer program. Two normal males participated in measuring the motion of unrecognized and recognized walking. Six infrared cameras and four force plates were used and sixteen reflective markers were attached to the subject to capture the motion. A musculoskeletal model was generated anatomically by using ADAMS(MSC software corp., USA) and LifeMOD(Biomechanics Research Group Inc, USA). The inverse dynamic simulation and forward dynamic simulation were also performed. The result of simulation was similar to the experimental result. This study provides the base line for dynamic simulation of the falling walking. It will be useful to simulate various another pathologic gaits for old peoples.
보행속도에 따른 지면보행과 Treadmill 보행의 비교: 운동분석 및 에너지 소모
손량희,최희석,손종상,황성재,김영호,Sohn, R.H.,Choi, H.S.,Son, J.S.,Hwang, S.J.,Kim, Y.H. 대한의용생체공학회 2009 의공학회지 Vol.30 No.3
In this study, treadmill walking and overground walking were compared at the same condition based on kinematics and energy expenditures(EE). In addition, we compared the actual energy expenditure and calculated EE by treadmill. The kinematics of treadmill and overground walking were very similar. The values at each joint were significantly different(P<0.05), but magnitude of the difference was generally less than 4$^{\circ}$. In the EE using cardiopulmonary exercise, EE of treadmill walking was significantly greater when measured on the overground. It seemed to be the increased stress during the gait by the continuous movement of the belt. As the velocity increased, there was significant difference between actual EE and calculated EE by treadmill due to EE curve increasing exponentially. Therefore the further study would be required to find the correlation of the two methods and calibrate the values from them.