• The Journal of Korean Academy of Prosthodontics
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• v.37 no.1
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• pp.71-92
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• 1999

This study is to analyze the stress and displacement on the jaws during the bilateral and unilateral clenching task on three dimensional finite element model of the dentated skull. For this study, the computed tomography(G.E.8800 Quick, USA) was used to scan the total length of human skull in the frontal plane at 1.9mm intervals. The CAD data were extracted from the tomograms through digitizer(Summa Sketch III, USA) and then reconstructed by means of the spline method in the CAD program. In this project, a commercial software I-DEAS(Master Series ver-sion 3.0, SDRC Inc, USA) was used for three-dimensional stress analysis on the finite element model. which consists of articular disc, maxilla, mandible, teeth, periodontal ligament and cranium. The results are as follows. ; 1. During the bilateral clenching, each major muscle forces caused high stresses on various areas of skull: masseter muscle on articular disc and teeth ; temporal muscle on mandible and periodontal ligament ; medial pterygoid muscle on the temporomandibular joint. During the unilateral clenching, masseter muscle induced the maximum stress ; medial pterygoid muscle the minimum stress. 2. During the bilateral clenching, higher compressive stresses on articular disc were generated by the masseter muscle and higher deformation occurred on the most front outer sites. And during the unilateral clenching, temporal muscle and medial pterygoid muscle exerted their forces to twist temporomandibular joint area of the balancing side and induced a higher compressive stresses on the front outer sites of articular disc. 3. During the bilateral clenching, the masseter muscle bended the mandible outwardly, and then caused tensile stresses on the lingual surface of mandibular symphysis. And the medial pterygoid muscle caused tensile stresses on the labial surface of mandibular symphysis. 4. When each muscles were simultaneously applied on jaws, a high stress and displacement took place on mandible rather than on the maxilla. Also, a high stress and displacement took place during the unilateral clenching rather than during the bilateral clenching.

• Journal of Microbiology and Biotechnology
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• v.33 no.7
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• pp.915-925
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• 2023

Sarcopenia is defined as loss of muscle mass and strength due to aging. Recent studies show that sarcopenia may improve via the gut-muscle axis, suggesting that gut health may affect muscle phenotypes. In this study, we aimed to investigate the ability of Lactobacillus rhamnosus JY02 as a probiotic strain isolated from kimchi to alleviate sarcopenia. L. rhamnosus JY02-conditioned medium (CM) reduced dexamethasone (DEX)-induced myotube diameter atrophy and expression of muscle degradation markers (MuRF1 and atrogin-1) in C2C12 cells. The amelioration of sarcopenia was investigated by measuring body composition (lean mass), hand grip strength, myofibril size (using histological analysis), and mRNA and protein expression of muscle-related factors in a DEX-induced mouse model. The results of these analyses showed that L. rhamnosus JY02 supplementation promoted the production of muscle-enhancement markers (MHC Iβ, MHC IIα, and Myo-D) and reduced both the production of muscle degradation markers and the symptoms of muscle atrophy (loss of lean mass and muscle strength). We also found decreased levels of pro-inflammatory cytokines (IL-6, IFN- γ) and increased levels of anti-inflammatory cytokines (IL-10) in the serum of DEX+JY02-administered mice compared to those in DEX-treated mice. Overall, these results suggest that L. rhamnosus JY02 is a potent probiotic supplement that prevents sarcopenia by suppressing muscle atrophy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.971-972
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1435-1436
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• 2011

• Journal of the Optical Society of Korea
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• v.18 no.1
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• pp.55-59
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• 2014

Sarcopenia, or reduced muscle mass and volume, is due to various factors such as senile change, neuronal degeneration, drug, malignancy, and sepsis. Sarcopenia with the aging process has been evidenced by the decline in muscle mass by 0.5 to 1% per year with 3-5% reduction in muscle strength for 10 years between the ages of 40 and 50, and a 1-2% of decline of mass every year in people aged 60-70. Therefore, early diagnosis and understanding the mechanism of sarcopenia are crucial in the prevention of muscle loss. However, it is still difficult to image changes of muscle microstructure due to a lack of techniques. In this study, we developed an animal model using denervated rats to induce a rapid atrophy in the tibialis anterior (TA) and imaged its structural changes using optical coherence tomography (OCT) along with histologic and ultrasound analyses. Ultrasound showed changes of overall muscle size. Histology revealed that the atrophic TA muscle displayed an increased size variability of muscle fiber and inflammatory changes. Three dimensional OCT imaged the changes of perimysial grid and muscle fiber structure in real time without sacrifice. These observed advantages of multimodal imaging using OCT and ultrasound would provide clinical benefits in the diagnosis of sarcopenia.

• Journal of the Ergonomics Society of Korea
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• v.28 no.3
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• pp.1-6
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• 2009

Recently, importance of the rehabilitation of hand pathologies as well as the development of high-technology hand robot has been increased. The biomechanical model of hand is indispensable due to the difficulty of direct measurement of muscle forces and joint forces in hands. In this study, a three-dimensional biomechanical model of four fingers including three joints and ten muscles in each finger was developed and a mathematical relationship between neural commands and finger forces which represents the enslaving effect and the force deficit effect was proposed. When pressing a plate under the flexed posture, the muscle forces and the joint forces were predicted by the optimization technique. The results showed that the major activated muscles were flexion muscles (flexor digitorum profundus, radial interosseous, and ulnar interosseous). In addition, it was found that the antagonistic muscles were also activated rather than the previous models, which is more realistic phenomenon. The present model has considered the interaction among fingers, thus can be more powerful while developing a robot hand that can totally control the multiple fingers like human.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.60
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• pp.37-46
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• 2000

A biomechanical model of lower extremity in seated postures was developed to assess muscular activities of lower extremity involved in a variety of foot pedal operations. The model incorporated four rigid body segments with the twenty-four muscles to represent lower extremity This study deals with quasi-static movement to investigate dynamic movement effect in seated foot operation. It is found that optimization method which has been used for modeling the articulated body segments does not predict the forces generated from biarticular muscles and antagonistic muscles reasonably. So, the revised nonlinear optimization scheme was employed to consider the synergistic effects of biarticular muscles and the antagonistic muscle effects from the stabilization of the joint. For the model validation, three male subjects performed the experiments in which EMG activities of the nine lower extremity muscles were measured. Predicted muscle forces were compared with the corresponding EMG amplitudes and it showed no statistical difference. For the selection of optimal seated posture, a physiological meaningful criterion was developed for muscular load sharing developed. For exertion levels, the transition point of type F motor unit of each muscle is inferred by analyzing the electromyogram at the seated postures. Also, for predetermined seated foot operations exertion levels, the recruitment pattern is identified in the continuous exertion, by analyzing the electromyogram changes due to the accumulated muscle fatigue.

• Journal of Biomedical Engineering Research
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• v.30 no.3
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• pp.241-246
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• 2009

Since inappropriate muscle forces mean that people cannot perform some activities related to roles of the muscle, muscle forces have been considered as an important parameter in clinic. Therefore, many methods have been introduced to estimate muscle forces indirectly. One of the methods is muscle tissue dynamics and it is widely used in commercial softwares including musculoskeletal model, such as SIMM. They, however, need motion data captured from 3-dimensional motion analysis system. In this study, we introduced an algorithm to estimate muscle forces in real-time by using joint angles. The heel-rise movements were performed for a normal with 3-dimensional motion analysis system, EMG measurement system, and electrogoniometers. Joint angles obtained from electrogoniometers and EMG signals were used to estimate muscle forces. Simulation was performed to find muscle forces using motion data which was imported into musculoskeletal software. As the results, muscle lengths and forces from the developed algorithm were similar to those from commercial software in pattern. Results of this study would be helpful to implement a tool to calculate reasonable muscle forces in real-time.

• Herbal Formula Science
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• v.29 no.1
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• pp.45-55
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• 2021

Objectives : This study was conducted to evaluate the anti-atrophic effect of polycan in dexamethasone-induced skeletal muscle atrophy in vitro model. Methods : C2C12 myoblast were differentiated into myotube by 2% horese serum medium for 6 days, and then treated polycan extract at different concentrations for 24h. The effect of dexamethasone on the induction of muscle atrophy and expression of atrophy-related genes in differentiated C2C12 myotubes using a GSH, ROS, real-time PCR, western blots analysis. Results : The results showed that Treatment with polycan (100 and 200 ㎍/㎖) noncytotoxic levels on both myoblast and myotube. Polycan decreased the ROS level overproduced with dexamethasone and improved the depletion of GSH level. Dexamethasone showed a decrease in myotube diameter, which was associated with up-regulation muscle-specific ubiquitin ligases markers, such as atrogin-1, FoxO3, myostatin and muscle RING finger-1 (MuRF1), and down-regulation of myogenin, MEF2, Myogenic regulatory factor 5, 6 and MyoD. The results showed that polycan treatment significantly dose-dependently inhibited it. Furthermore, decreased expressions of PI3K/Akt signal pathway by dexamethasone were reversed by treatment with polycan. Conclusions : Thus, polycan suppresses dexamethasone induced muscle atrophy in C2C12 myotube in vitro model through activation of PI3K/Akt pathway and protective effect of improve skeletal muscle function.

• Journal of Electrical Engineering and Technology
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• v.10 no.6
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• pp.2413-2419
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• 2015

Core spinal muscles are related to trunk stability and assume the main role of stabilizing the spine during daily activities; strengthening of core muscles around the spine can therefore reduce the chance of back pain. The objective of the study was to investigate the effect of core muscle strengthening in the spine during spine stabilization exercise using a whole body tilt device. To achieve this, a validated musculoskeletal (MS) model of the whole body was used to replicate the input motion from the whole body tilting exercise. An inverse dynamics analysis was executed to estimate spine loads and muscle forces depending on the tilting angles of the exercise device. The activation of long and superficial back muscles such as the erector spinae (iliocostalis and longissimus) were mainly affected by the forward direction (-40°) of the tilt, while the front muscles (psoas major, quadratus lumborum, and external and internal obliques) were mainly affected by the backward tilting direction (40°). Deep muscles such as the multifidi and short muscles were activated in most directions of the rotation and tilt. The backward directions of the tilt using this device could be carefully applied for the elderly and for rehabilitation patients who are expected to have less muscle strength. In this study, it was shown that the spine stabilization exercise device can provide considerable muscle exercise effect.