• Journal of Biomedical Engineering Research
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• v.22 no.2
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• pp.151-156
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• 2001

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.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1554-1559
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• 2003

This study validated the musculoskeletal model of the human lower extremity by comparative study between calculated muscle parameters through simulation using modified hill-type model and measured them through isokinetic exercise. And the relationship between muscle forces and moments participated in motion was quantified from the results of simulation. For simulation of isokinetic motion, a three-dimensional anatomical knee model was constructed using trials of gait analysis and the EMG-force model was used to determine muscle activation level exciting muscles. The modified Hill-type model was used to calculate individual muscle forces and moments in dynmaic analysis and the results were validated by comparing them of experiments on BIODEX. The results showed that there was a high correlation between calculated torques from simulation and measured them from experiments for isokinetic motion(R=0.97). Therefore we concluded that the simulation by using musculoskeletal model was so useful means to predict and convalesce musculoskeletal-related diseases, and analyze unrealizable experiment such as clash condition.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.2
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• pp.322-327
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• 2003

Based on dynamic muscle model to construct efficient face animation in this paper 30 face modelling techniques propose. Composed face muscle by faceline that connect 256 point and this point based on dynamic muscle model, and constructed wireframe because using this. After compose standard model who use wireframe, because using front side and side 2D picture, enforce texture mapping and created 3D individual face model. Used front side of characteristic points and side part for correct mapping, after make face that have texture coordinates using 2D coordinate of front side image and front side characteristic points, constructed face that have texture coordinates using 2D coordinate of side image and side characteristic points.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.8
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• pp.1187-1193
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• 2013

In this paper, we present realistic 3D head modeling and facial expression systems. For 3D head modeling, we perform generic model fitting to make individual head shape and texture mapping. To calculate the deformation function in the generic model fitting, we determine correspondence between individual heads and the generic model. Then, we reconstruct the feature points to 3D with simultaneously captured images from calibrated stereo camera. For texture mapping, we project the fitted generic model to image and map the texture in the predefined triangle mesh to generic model. To prevent extracting the wrong texture, we propose a simple method using a modified interpolation function. For generating 3D facial expression, we use the vector muscle based algorithm. For more realistic facial expression, we add the deformation of the skin according to the jaw rotation to basic vector muscle model and apply mass spring model. Finally, several 3D facial expression results are shown at the end of the paper.

• Journal of Biomedical Engineering Research
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• v.10 no.1
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• pp.11-16
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• 1989

This paper describes the AR model of EMG signal during maximum voluntary contraction. By comparing the AR coefficients and the reflection coefficients of the AR model with the median frequency of power spectrum, it is proved that muscle fatigue can be measured by the AR and the reflection coefficients. In the estimation procedure of AR model parameter, the autocorrelation method is superior to the covariance method, and it is determined that the optimal order is six. As the muscle becomes fatigue, the median frequency of power spectrum is declined, and the AR coefficient [$a_1$] and the reflection coefficient [$k_1$] are also decreased. Therefore the muscle fatigue can be measured by the AR parameter.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.130-136
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• 2010

For stability analysis of the lumbar spine, the hypothesis presented is that the disc has stress sensors driving feedback mechanism, which could react to the imposed loads by adjusting the contraction of the muscles. Fusion in the motion segment of the lumbar spinal column is believed to alter the stability of the spinal column. To identify this effect finite element (FE) models combined with optimization technique was applied and quantify the role of each muscle and reaction forces in the spinal column with respect to the fusion level. The musculoskeletal FE model was consisted with detailed whole lumbar spine, pelvis, sacrum, coccyx and simplified trunk model. Vertebral body and pelvis were modeled as a rigid body and the rib cage was constructed with rigid truss element for the computational efficiency. Spinal fusion model was applied to L3-L4, L4-L5, L5-S1 (single level) and L3-L5 (two levels) segments. Muscle architecture with 46 local muscles was used as acting directions. Minimization of the nucleus pressure deviation and annulus fiber average axial stress deviation was selected for cost function. As a result, spinal fusion produced reaction changes at each motion segment as well as contribution of each muscle. Longissimus thoracis and psoas major muscle showed dramatic changes for the cases of L5-S1 and L3-L5 level fusion. Muscle force change at each muscle also generated relatively high nucleus pressure not only at the adjacent level but at another level, which can explain disc degeneration pattern observed in clinical study.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.6
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• pp.433-439
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• 2022

Muscle fatigue models to predict maximum endurance time (MET) are broadly classified as either 'empirical' or 'theoretical'. Empirical models are based on fitting experimental data and theoretical models on mathematical representations of physiological process. This paper examines the effectiveness of dynamic muscle fatigue model as theoretical model to predict maximum endurance time during forearm isometric contraction. Forty volunteers (20 females, 20 males) are participated in this study. Empirical models (exponential model and power model) and theoretical model (dynamic muscle fatigue model) are used to compare. Mean absolute deviation (MAD), correlation coefficient (r) and intraclass correlation (ICC) are calculated between theoretical model and empirical models. MAD are below 3.5%p, r and ICC are above 0.93 and 0.87, respectively. This results demonstrate that dynamic muscle fatigue model as theoretical model is valid to predict MET.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.7 s.184
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• pp.152-158
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• 2006

The objective of this work is to develop the knee joint model for representing various pendulum motions and quantifying the spasticity. Knee joint model included the extension and flexion muscles. The joint moment consists of both the active moment from the stretch reflex and the passive moment from the viscoelastic joint properties. The stretch reflex was modeled as nonlinear feedback of muscle length and the muscle lengthening velocity, which is Physiologically-feasible. Moreover, we modeled the spastic reflex as having dynamic threshold to account far the various pendulum trajectories of spastic patients. We determined the model parameters of three patients who showed different pendulum trajectories through minimization of error between experimental and simulated trajectories. The simulated joint trajectories closely matched with the experimental ones, which show the proposed model can predict pendulum motions of patients with different spastic severities. The predicted muscle force from spastic reflex appeared more frequently in the severe spastic patient, which indicates the dynamic threshold relaxes slowly in this patient as is manifested by the variation coefficient of dynamic threshold. The proposed method provides prediction of muscle force and intuitive and objective evaluation of spasticity and it is expected to be useful in quantitative assessment of spasticity.

• Journal of Life Science
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• v.31 no.2
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• pp.137-143
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• 2021

Muscle atrophy refers to a decrease in muscle cells due to damage to muscle fibers. It is reported that muscle atrophy is caused by heart disease, diabetes, and other chronic diseases related to aging. The purpose of this study is to reveal the inhibitory effects of seaweed extracts, which are widely consumed in Korea, and alginic acid on muscle cell damage in muscle atrophy and regeneration models. We found that seaweed extracts (U) and alginic acid (A) attenuated TNF-α-induced muscle atrophy in differentiated C2C12 myoblast cells and inhibited muscle atrophy markers such as MuRF1 and MAFbx. In addition, U and A also regulated ubiquitination marker FoxO1 protein. To confirm the muscle regeneration effect in animal tissue, cardiotoxin (CTX) was used for the regeneration model. Six hours after CTX injection, gastrocnemius muscle volume was increased compared to control. Otherwise, the muscle volume of the U and A treatment groups was not changed. U and A also upregulated regeneration markers MyHC and PGC-1α in a CTX mouse model. These results indicate that seaweed extracts and alginic acid, a seaweed component, are applicable to senile sarcopenia by inhibiting muscle loss and promoting muscle regeneration.

• Journal of Biomedical Engineering Research
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• v.20 no.3
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• pp.315-321
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• 1999

The purpose of this study is to develop a mathematical model for system identification in order to predIct muscle force based on eledromyographic signal. Therefore, a finding of the relalionship between characteristics of electromyographic signal and the corre spondng muscle force should be necessiiry through dynamic, joint model. To develop the dynamic joint model, the upper limb mcludmg the wrist and elbow joint has been considered. The kinematic and dynamic data, such as joint angular displacement, velocity, deceleration along with the moment of inertla, required to establish the dynamic model has been obtained by electrical flexible goniometer which has two degree-of-frcedoms. ln this model, muscle force can be predicted only electromyographs through the relationship between the integrated lorce and the mtegrated electromyographic signal over the duration of muscle contraclion in this study.