• 한국정밀공학회지
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• 제23권7호
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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.

• 한국정밀공학회지
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• 제24권12호
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• pp.20-28
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• 2007

• 한국산학기술학회논문지
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• 제13권3호
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• pp.1229-1237
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• 2012

본 연구는 파악력의 강도가 두 가지 팔 자세에서 어깨근육 근활성도에 어떠한 영향을 미치는지 알아보기 위하여 실시되었다. 건강한 성인 22명(남 11명, 여 11명)을 대상으로 실시하였고, 4가지 파악력(최대 파악력의 0%, 30%, 50%, 70%)을 팔의 중립 자세와 팔 $90^{\circ}$ 거상 자세에서 적용 했을 때 상승모근, 하승모근, 극하근, 전삼각근, 후삼각근의 근활성도를 표면 근전도를 이용하여 측정하였다. 팔 중립 자세에서는 파악력의 강도에 따라 극하근, 전삼각근, 후삼각근이 유의한 차이를 보였고(p<0.05), 팔 $90^{\circ}$ 거상 자세에서는 전삼각근, 후삼각근이 유의한 차이를 보였다(p<0.05). 본 연구의 결과, 2가지 팔의 자세에서 각각 파악력의 강도에 따라 어깨근육 근활성도가 변화됨을 확인하였다. 손 쥐기 과제를 중립자세에서 실시할 경우 어깨관절 안정근인 극하근이 활성화되고, 팔 $90^{\circ}$ 거상 자세에서는 삼각근을 억제된다는 점을 고려하여, 손을 사용하는 작업 시 인간공학적 접근으로 어깨 손상의 예방과 손상 후 재활 훈련 시 효율적인 전략으로 사용할 수 있을 것으로 여겨진다.

• 대한전기학회논문지:시스템및제어부문D
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• 제50권5호
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• pp.247-254
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• 2001

Silent period(SP) is transient stops of muscle activity that are induced by mechanical or electrical stimulus and the duration of silent period is a important parameter that have been associated with symptoms of masticatory dysfunction. Muscle fatigue is induced by sustained muscular contractions. It is associated with the external manifestations as the inability to maintain a desired force output, muscular tremor, and localized pain. Muscle fatigue is a parameter that have been measured or monitored the deterioration of a performance of muscles. On the study of relationship between SP and masticatory muscle fatigue, Nagasawa suggested that SP increases up to 3 min. from the beginning of clenching when the subjects performed sustained contractions at 50% maximum clenching level. In this paper, in order to evaluate a relationship between SP and muscle fatigue, 10 SPs per 1 minute are measured at 10%, 20%, 50% maximum clenching level. We used the median frequency in order to quantify the degree of muscle fatigue. However, the results shows that the duration of silent period was not significantly affected by differing levels of muscle fatigue. Therefore, we suggest that the SP is not increased or decreased as the results of muscle fatigue, also the origin of the SP generation mechanism is discussed.

• The Journal of Korean Physical Therapy
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• 제19권6호
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• pp.17-22
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• 2007

Purpose: To evaluate the quantitative isometric muscle strength of shoulder girdle and the test reliability using by the equipment, named 'IsoTrack', selected by authors in the former studies. Methods: Thirty healthy subjects (9 men, 21 women) were recruited in two sessions, one for intratester and intertester reliability tests and the other quantitative isometric muscle strength tests. The neck flexion, extension and scapular elevation muscle strength was measured using a force measuring device as IsoTract. Results: Intraclass correlation coefficients for intratester reliability of the all subjects ranging between 0.96 and 0.97. For intertester reliability, the ICC and Pearson correlation correspond to 0.84 and 0.78. We gauged muscle strength of shoulder girdle muscles based on it and indicated quantified isometric muscle strength of women and men in left and right side. Conclusion: We concluded that there were high reiliability of isometric muscle strength of neck and shoulder girdle. Also, we gauged muscle strength of shoulder girdle muscles based on it and indicated quantified isometric muscle strength in left and right side in women and men. So this findings may assist in the measure of whole body muscle strength.

• 드라이브 ㆍ 컨트롤
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• 제18권4호
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• pp.77-83
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• 2021

With the progress in virtual reality technology, various virtual objects can be displayed using head-mounted displays (HMD). However, force feedback sensations such as pushing against a virtual object are not possible with an HMD only. Focusing on force feedback, desktop-type devices are generally used, but the user cannot move in a virtual space because such devices are fixed on a desk. With a wearable force feedback device, users can move around while experiencing force feedback. Therefore, the authors have developed a wearable force feedback device using a magnetorheological fluid clutch and pneumatic rubber artificial muscle, aiming at presenting the elasticity, friction, and viscosity of an object. To date, we have developed a wearable four-degree-of-freedom (4-DOF) force feedback device and have quantitatively evaluated that it can present commanded elastic, frictional, and viscous forces to the end effector. However, sensory evaluation with a human has not been performed. In this paper, therefore, we conduct a sensory evaluation of the proposed method. In the experiment, frictional and viscous forces are rendered in a virtual space using a 4-DOF force feedback device. Subjects are asked to answer questions on a 1- to 7-point scale, from 1 (not at all) to 4 (neither) to 7 (strongly). The Wilcoxon signed rank test was used for all data, and answer 4 (neither) was used as compared standard data. The experimental results confirmed that the user could feel the presence or absence of viscous and frictional forces. However, the magnitude of those forces was not sensed correctly.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.974-979
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• 2004

The fluidic muscle cylinder consist of an air bellows tube, flanges and lock nuts. It's features are softness of material and motion, simplicity of structure, low production cost and high power efficiency. In this study, we carried out the finite element modelling and analysis about the main design variables such as contraction ration and force, diameter increment of fluidic muscle cylinder. On the basis of finite element analysis, the prototype of fluidic muscle cylinder was manufactured and tested. Finally, we compared the results between the test and the finite element analysis.

• 대한의용생체공학회:의공학회지
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• 제29권3호
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• pp.222-230
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• 2008

This paper introduces a method of estimating the knee joint moment developed during MVC. By combining the Hill-type muscle model and analytic results on moment arm and musculotendon length change as a function of hip and knee joint angle, the knee joint moment at a specific knee joint angle during MVC is determined. Many differences between the estimated results and the experimental data are noted. It is believed that these differences originate from inaccurate information on the muscle-tendon parameters. The establishment of exact values for the subject's muscle parameters is almost impossible task. However, sensitivity analysis shows that the tendon slack length is the most critical parameter when applying the Hill-type muscle model. The effect of a change of this parameter on the muscle length force relationship is analyzed in detail.

• 한국축산식품학회지
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• 제39권1호
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• pp.151-161
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• 2019

The objective of this study was to investigate the correlations of marbling characteristics, including marbling score, intramuscular fat (IMF) content, and fleck traits, with meat quality traits and histochemical characteristics of the longissimus thoracis muscle from Hanwoo steers. Marbling fleck characteristics, especially area, number, and fineness (F) index, measured by computerized image analysis were strongly correlated with marbling score and IMF content (p<0.05). However, coarseness (C) index and F/C ratio were somewhat limited relationships with marbling score. In contrast, the IMF content and the number of smaller white flecks increased with increasing lightness value (p<0.05). Moreover, beef with higher marbling scores showed lower cooking loss and Warner-Bratzler shear force value compared to beef with lower marbling scores (p<0.05). Regarding the muscle bundle traits, as number of bundle increased, number of marbling flecks increased (p<0.05), although most marbling characteristics did not have significant correlation with muscle fiber or bundle characteristics.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 추계학술대회 논문집
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• pp.169-170
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• 2007