http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
개별검색 DB통합검색이 안되는 DB는 DB아이콘을 클릭하여 이용하실 수 있습니다.
통계정보 및 조사
예술 / 패션
<해외전자자료 이용권한 안내>
- 이용 대상 : RISS의 모든 해외전자자료는 교수, 강사, 대학(원)생, 연구원, 대학직원에 한하여(로그인 필수) 이용 가능
- 구독대학 소속 이용자: RISS 해외전자자료 통합검색 및 등록된 대학IP 대역 내에서 24시간 무료 이용
- 미구독대학 소속 이용자: RISS 해외전자자료 통합검색을 통한 오후 4시~익일 오전 9시 무료 이용
※ 단, EBSCO ASC/BSC(오후 5시~익일 오전 9시 무료 이용)
A patient-specific musculoskeletal model, whose parameters can be identified noninvasively, was developed for the automatic generation of patient-specific stimulation pattern in FES. The musculotendon system was modeled as a torque-generator and all the passive systems of the musculotendon working at the same joint were included in the skeletal model. Through this, it became possible that the whole model to be identified by using the experimental joint torque or the joint angle trajectories. The model parameters were grouped as recruitment of muscle fibers, passive skeletal system, static and dynamic musculotendon systems, which were identified later in sequence. The parameters in each group were successfully estimated and the maximum normalized RMS errors in all the estimation process was 8%. The model predictions with estimated parameter values were in a good agreement with the experimental results for the sinusoidal, triangular and sawlike stimulation, where the normalized RMS error was less than 17%, Above results show that the suggested musculoskeletal model and its parameter estimation method is reliable.
A computer model of the musculoskelotal system that provides accurate prediction of muscle force and body movement trom the stimulation input is desired for the effective control system design in FES. This paper aims to investigate the fundamental properties of the gradual muscle force potentiation that was not included in the previous muscle models, for future development of a model that provides vetter prediction of FES-induced muscle force and body movement. Specifically, hou the muscle length was investigated. The experimental results showed that both the force increment ratio and the time-to-peak during electrical stimulation decreased with stimulatino frequency. When the muscle potentiation state was saturated by preceding stimulation. the force did not increase any more during additive stimulation. Muscle length significantly affected the force potentiation in such a way that the force increment ratio decreased with muscle length. A new model of the muscle potentiation based on these results is desired in the future. 기능적 전기자극(FES)에 의한 사지운동의 효과적인 제어를 위해서는, 전기자극을 입력으로 하여 근력 및 운동을 정확히 출력하는 근골격모델이 요망된다. 이 연구에서는 FES에 의한 근력 및 운동을 보다 정확히 예측할 수 있는 모델을 작성하기 위하여, 기존의 근육모델에서는 포함되지 않았던 근력의 점진적 강화현상에 대한 기초적 성질을 조사하는 것을 목적으로 한다. 구체적으로는, 일정강도의 표면자극에 대한 근력의 강화현상이 주파수, 자극이력, 근육길이에 어떻게 의존하는지를 조사하였다. 실험결과로부터, 자극의 주파수가 높을수록 초기근력에 대한 자극중의 근력의 증가도는 작아지고 근력의 피크에 도달하는 시간이 짧아지는 것을 알 수 있었다. 선행 자극에 의해 근육의 내부적인 강화상태가 포화되면 근력은 추가적인 자극에 대해서도 더 이상 증가하지 않았다. 자극시의 근육의 길이는 근력강화에 큰 영향을 미쳤으며, 근육의 길이가 짧을수록 증가도가 컸다. 장래에는 이러한 결과를 토대로 한 새로운 근력강화의 모델이 요망된다.
Objective Compared to elderly men, elderly women have substantially reduced performance of postural balance and greater risk of falls. To investigate the effect of age and sex on electromyographic (EMG) reaction time of tibialis anterior muscle contraction. Method Fifty-nine elderly subjects and 29 young subjects participated in this study. Subjects were instructed to dorsiflex the ankle of the dominant leg as forcefully and quickly as possible in response to audible beeps. EMG activity was recorded over the tibialis anterior muscle and delays in initiation and termination of EMG signal were measured by two examiners. Mean and intrasubject variability of each delay were used as outcome measures. Results Both the intra-examiner and inter-examiner reliability of delay variables were above 0.97. Delays in initiation and termination of muscle contraction, as well as their intrasubject variability, were significantly greater in the elderly (p<0.01). However, there were no sex differences or interaction in all outcome measures. Conclusion These results demonstrate that the EMG reaction time and their variability increase in the elderly population with no sex difference.
The purpose of this study is to generate cycling motion for FES (functional electrical stimulation) using knee muscles only. We investigated the possibility by simulation. The musculoskeletal model used in this simulation was simplified as 5-rigid links and 2 muscles (knee extensor and flexor). For the improvement of the present feedforward control in FES, we included feedback path in the control system. The control system was developed based on the biological neuronal system and was represented by three sub-systems. The first is a higher neuronal system that generates the motion command for each joint. The second is the lower neuronal system that divides the motion command to each muscle. And the third is a sensory feedback system corresponding to the somatic sensory system. Control system parameters were adjusted by a genetic algorithm (GA) based on the natural selection theory. GA searched the better parameters in terms of the cost function where the energy consumption, muscle force smoothness, and the cycling speed of each parameter set (individual) are evaluated. As a result, cycling was implemented using knee muscles only. The proposed control system based on the nervous system model worked well even with disturbances.
The purpose of this paper is to suggest a practical and simple method for the identification of the joint mechanical properties and to apply it to human knee joints. The passive moment at a joint was modeled by three mechanical parts, that is, a gravity term, a linear damper term and a nonlinear spring term. Passive pendulum tests were performed in 5 fat and 5 thin men. The data of pendulum test were used to identify the mechanical properties of joints through sequential quadratic programming (SQP) with random initial values. The identification was successful where the normalized root-mean-squared (RMS) errors between the simulated and experimental joint angle trajectories were less than 10%. The parameter values of mechanical properties obtained in this study agreed with literature. The inertia, gravity and the damping constant were greater at fat men, which indicates more resistance to body movement and more energy consumption for fat men. The suggested method is noninvasive and requires simple setup and short measurement time. It is expected to be useful in the evaluation of joint pathologies.
The purpose of this paper is to develop a more precise damper model of the joint for the quantification of the joint mechanical properties. We modified the linear damper model of a knee joint model to nonlinear one. The normalized RMS errors between the simulated and measured joint angle trajectories during passive pendulum test became smaller with the nonlinear damper model than those of the linear one which indicates the nonlinear damper model is better in precision and accuracy. The error between the experimental and simulated knee joint moment also reduced with the nonlinear damper model. The reduction in both the trajectory error and the moment error was significant at the latter part of the pendulum test where the joint angular velocity was small. The nonlinearity of the damper was significantly greater at thin subject group and this indicates the nonlinearity is a useful index of joint mechanical properties.