관절계 역학적 특성의 정량화를 위한 비선형 댐퍼모델

엄광문(Gwang-Moon EOM),이창한(Chang-Han LEE),김철승(Chul-Seung KIM),허지운(Ji-Un Heo) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.4

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.

전기자극을 이용한 상실된 운동기능의 회복

엄광문(Gwang Moon Eom),강곤(Gon Khang),이정한(Jeong Han Yi),Nozomu HOSHIMIYA Korean Society for Precision Engineering 2003 한국정밀공학회지 Vol.20 No.1

인류 보행의 진화

엄광문(Gwang Moon EOM),하세 카즈노리(Kazunori HASE) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.5

This research was designed to investigate biomechanical aspects of the evolution based on the hypothesis of dynamic cooperative interactions between the locomotion pattern and the body shape in the evolution of human bipedal walking. The musculoskeletal model used in the computer simulation consisted of 12 rigid segments and 26 muscles. The nervous system was represented by 18 rhythmic pattern generators. The genetic algorithm was employed based on the natural selection theory to represent the evolutionary mechanism. Evolutionary strategy was assumed to minimize the cost function that is weighted sum of the energy consumption, the muscular fatigue and the load on the skeletal system. The simulation results showed that repeated manipulations of the genetic algorithm resulted in the change of body shape and locomotion pattern from those of chimpanzee to those of human. It was suggested that improving locomotive efficiency and the load on the musculoskeletal system are feasible factors driving the evolution of the human body shape and the bipedal locomotion pattern. The hypothetical evolution method employed in this study can be a new powerful tool for investigation of the evolution process.

진자운동검사를 이용한 슬관절 경직의 정량적 평가

엄광문(Gwang Moon Eom),김철승(Chul-Seung Kim),공세진(Se-Jin Kong),김종문(Jong-Moon Kim),이순혁(Soon-Hyuk Lee) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.11

관절계 역학적 특성의 정량적 평가방법

엄광문(Gwang-Moon EOM),김석주(Seok-Joo KIM),한태륜(Tai-Ryoon HAN) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.11

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.

슬관절 근육만을 이용한 FES 싸이클링

엄광문(Gwang-moon EOM),김철승(Chul-seung KIM),하세 카즈노리(Kazunori HASE) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.8

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.

파킨슨씨 병 환자와 정상인의 입각기시간과 상비율의 비교

김지원,엄광문,Kim, Ji-Won,Eom, Gwang-Moon 대한의용생체공학회 2006 의공학회지 Vol.27 No.6

The purpose of this study is to investigate the gait characteristics in Parkinson's disease patients. Specifically, the total stance time and the ratio of each stance phase (heel strike, mid-stance, propulsion) are analyzed from the foot-pressure measurement system which requires low cost and small space compared to the conventional gait analysis system. The gait characteristics were analyzed in 23 Parkinson's disease patients (before and after L-dopa medication), 34 elderly (sixties) normal subjects and 21 young (twenties) normal subjects. Bradykinesia global score (self-developed score of slowness of body movement) of patients before medication was determined to see the relationship between the score and the gait characteristics. The total stance time was greater in the erde. of patients, elderly, youngs (p<0.05). The phase ratio of heel strike and propulsion was smaller and that of mid-stance was greater in the order of patients, elderly, youngs (p<0.05). However, there was no significant difference in the above gait characteristics of patients before and after medication. There was a tendency, though statistically non-significant, that the total stance time is longer and the propulsion phase ratio is shorter in patients with greater Bradikinesia global scale, and this tendency was relieved after medication.

고령자의 족관절 근육 양측성 수축시의 전운동 반응시간

김지원,권유리,신재남,엄광문,김철승,박병규,홍정화,Kim, Ji-Won,Kwon, Yu-Ri,Shin, Jae-Nam,Eom, Gwang-Moon,Kim, Chul-Seung,Park, Byung-Kyu,Hong, Jung-Hwa 대한의용생체공학회 2010 의공학회지 Vol.31 No.3

The purpose of this study is to investigate the effects of sex and age and their interactions in premotor-time (PMT) of ankle muscle. Forty-eight elderly subjects (aged 65-90 years) and thirty young subjects (aged 19-27 years) participated in this study. Subject were instructed to perform maximal, voluntary, isometric, bilateral contraction of ankle muscle in reaction to auditory stimulus to determine PMT. As analysis variables, PMT, intrasubject variability of PMT and asymmetry of PMT between dominant and nondominant legs were used. As statistical analysis, two-way ANOVA was performed to assess the main effects of age group and sex and also their interactions. All variables showed significant age effects (p<0.01). However, no sex effect and interaction existed in all variables in both dominant and nondomiant legs. Theses results suggest that the PMT of ankle muscle is related to the age-related deterioration in postural control, however, not related to the sex-difference of fall incidence in the elderly population.

파킨슨병 환자의 경직에 대한 임상적 평가의 정량화

이재호,김지원,권유리,엄광문,고성범,김형식,이정한,이정환,Lee, Jae-Ho,Kim, Ji-Won,Kwon, Yu-Ri,Eom, Gwang-Moon,Koh, Seong-Beom,Kim, Hyung-Sik,Yi, Jeong-Han,Lee, Jeong-Whan 대한의용생체공학회 2010 의공학회지 Vol.31 No.4

The purpose of this study was to quantify the clinical assessment of rigidity at wrist in patients with Parkinson's disease. The experimental system was designed that the effect of gravity was negated by restricting motion at the horizontal plane and inertia was predetermined from a biomechanical measurement. Forty five patients with Parkinson's disease participated in this study. Viscoelastic properties were calculated from the experimental data acquired during intermittent passive movement of wrist. Viscoelastic constants correlated well with the rigidity scores of UPDRS, i.e., Spearman's r=0.733 and 0.905 for spring and damping constants, respectively. The results suggest that viscoelastic properties can be used as quantitative measures of rigidity.

FES 보행을 위한 휴대용 보행 이벤트 검출 시스템

孔世鎭(Se-Jin Kong),嚴光文(Gwang-Moon Eom),金哲承(Chul-Seung Kim),朴寬龍(Kwan-Yong Park) 대한전기학회 2006 전기학회논문지 D Vol.55 No.5

The purpose of this study is to develop a portable gait-event detection system which is necessary for the cycle-to-cycle FES(functional electrical stimulation) control of locomotion. To make the system portable, we made following modifications in the gait signal measurement system. That is, 1) to make the system wireless using Bluetooth communication, 2) to make the system small-sized and battery-powered by using low power consumption μP(ATmega8535L). The gait-events were analyzed in off-line at the main computer using ANN(Artificial Neural Network). The Proposed system showed no mis-detection of the gait-events of normal subject and hemiplegia subjects. The performance of the system was better than the previous wired-system.