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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.
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.
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.
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.
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.
파킨슨병 환자의 경직에 대한 약물과 DBS의 효과의 정량화
권유리(Yu-Ri Kwon),엄광문(Gwang-Moon Eom),박상훈(Sang-Hun Park),김지원(Ji-Won Kim),김민직(Min-Jik Kim),이혜미(Hye-Mi Lee),장지완(Ji-Wan Jang),고성범(Seong-Beom Koh) Korean Society for Precision Engineering 2013 한국정밀공학회지 Vol.30 No.5
This study aims to quantify the effects of medication (Med) and deep brain stimulation (DBS) on resting rigidity in patients with Parkinsons disease. We tested 10 limbs of five patients under each of four treatment conditions: 1) baseline, 2) DBS, 3) Med, 4) DBS + Med. Rigidity at the wrist joint was assessed using the Unified Parkinsons Disease Rating Scale (UPDRS). The examiner randomly imposed flexion and extension movement on patients wrist joint. Resistance to passive movement was quantified by viscoelastic properties. Not only rigidity score but also damping constant showed improvements in rigidity by DBS and Med treatments (p<0.05). This indicates that the viscosity can represent the change in rigidity due to DBS as well as Med, which was manifested by UPDRS score.
본태성 진전 환자의 진전특성에 대한 수행과제 및 부위의 영향
허재훈,김지원,권유리,엄광문,권도영,이찬녕,박건우,Heo, J.H.,Kim, J.W.,Kwon, Y.R.,Eom, Gwang-Moon,Kwon, D.Y.,Lee, C.N.,Park, K.W.,Manto, M. 대한의용생체공학회 2016 의공학회지 Vol.37 No.1
Essential tremor is a neurological disorder with a tremor of the arms and hands. It is well known that essential tremor is characterized by the postural tremor and the action tremor. There has been no report on the quantitative difference in the characteristics of two tremor types. The purpose of this study was to investigate the possible difference in tremor characteristics of postural and action tremors. Seventeen patients with essential tremor ($68.9{\pm}7.9years$, 7 men, 10 women) participated in this study. Patients performed the tasks of postural maintenance (arms outstretched) and daily actions (spiral drawing). Three-axes (pitch, roll and yaw) gyro sensors were attached on index finger, back of hand and forearm, from which the segment and the joint angular velocities were calculated. Outcome measure was the tremor amplitude defined as the root-mean-square mean of the vector-sum angular velocity at segments and joints. Two-way ANOVA showed that task and joint had main factor on the tremor amplitude (p < 0.05). Post-hoc analysis revealed that tremor amplitude at the metacarpo-phalangeal joint was not affected by task (p > 0.05). However, tremor amplitude at the wrist joint differed among the tasks (p < 0.05), and it was greater in the action tasks than in postural task. Tremor was greater at finger segments than at hand and forearm and it increased in action tasks. The results of this study would be helpful for the understanding and task-specific treatments of the essential tremor.