• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1600-1602
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• 2008

Various applications of exoskeleton system are reported in the area of military, healthcare, and industries. More the user gets help from exoskeleton system, more power is consumed. To resolve this design conflict, we suggest an energy efficient exoskeleton system which compensates muscle fatigue in isotonic and isometric contraction conditions. Fatigue compensated exoskeleton significantly reduced muscle fatigue while consumed less operation power. In addition, the level of fatigue compensation can be managed by motor control using various input profile. It can make user customized exoskeleton system.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.1152-1162
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• 2011

This study was function experiment or inspection of diagnosis x-ray unit at the hospital. It's how many changes tube voltage, tube current, DOSE value through the experiment depending on temperature increasing. The study want to know whether which parameter shown out of range or not how about image quality and so on. Increasing tube current and DOSE were not only too many radiation to the patient and radiation workers and make bad images but also the tube should be damaged by heat. This study was recommended proper exposure at intervals of seconds because passed inspection, reduced radiations for patient and the tube used long term. This results in the hospital's finances will be very helpful.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.8
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• pp.870-877
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• 2013

There has been much recent research interest in developing numerous kinds of human-machine interface. This field currently requires more accurate and reliable sensing systems to detect the intended human motion. Most conventional human-machine interface use electromyography (EMG) sensors to detect the intended motion. However, EMG sensors have a number of disadvantages and, as a consequence, the human-machine interface is difficult to use. This study describes a muscle volume sensor (MVS) that has been developed to measure variation in the outline of a muscle, for use as a human-machine interface. We developed an algorithm to calibrate the system, and the feasibility of using MVS for detecting muscular activity was demonstrated experimentally. We evaluated the performance of the MVS via isotonic contraction using the KIN-COM$^{(R)}$ equipment at torques of 5, 10, and 15 Nm.

• The Korean Journal of Physiology
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• v.20 no.1
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• pp.31-41
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• 1986

The sufficient myoplasmic $Ca^{++}$ to react with the contractile proteins is necessary to induce contraction of a cardiac muscle. These $Ca^{++}$ for the production of muscle contraction are supplied from the three recognized $Ca^{++}$ sources; internal $Ca^{++}$ release via the sarcoplasmic reticulum(SR), $Ca^{++}$ influx through a gated Ca-channel in the membrane as a Isi, and $Ca^{++}$ transport by the mechanism of Na/ca exchange. However, it is still controversial which $Ca^{++}$ sources act as a main contributor for myoplasmic $Ca^{++}$, Therefore, this study was undertaken in order to examine the $Ca^{++}$ sources for the contraction of frog ventricle. There is evidence that the SR is sparse in frog ventricular fibers, and that T-tubules are absent. Isolated ventricular strips of frog, Rana nigromaculata, were used in this experiment. Isometric tension was recorded by force transducer, and membrane potentials of ventricular muscles were measured through the intracellular glass microelectrodes, which were filled with 3M KCI and had resistance of $30{\pm}50M{\Omega}$. All experiments were performed at room temperature in a tris·buffered Ringer solution which was aerated with 100% $O_2$. Isotonic high K, low Na solution was used to induce K-contracture, K-contracture appeared at the concentration of 20 to 30mM-KCI and was potentiated in parallel with the increase in KCI concentration. The contracture had two components: an initial rapid phasic and a subsequent slow tonic contractile responses. Membrane Potentials measured at normal Ringer solution(2.5mM KCI) was -90 to -100 mV, and decreased linearly as the KCI concentration increased; -55mV at 20mM.KCI, -45mV at 30 mM.KCI, -30 mY at 50 mM.KCI, and -12 mV at 100 mM.KCI. K-contracture was evoked firstly at the membrane potential of -45 mV. The contracture was potentiated by the increase of bathing extracellular $Ca^{++}$ concentration. However, in the absence of $Ca^{++}$ the contracture was almost not induced by 50 mM.KCI solution. Caffeine(20mM) in normal Ringer solution, which is known to release $Ca^{++}$ from SR without substantial effects on the $Ca^{++}$ fluxes across the surface membrane, did not affect membrane potential and also not initiate contracture, but the caffeine in 20 mM-KCI Ringer solution produced a contracture. Above results suggest that the main $Ca^{++}$ source for the K·contracture of frog ventricle is $Ca^{++}$ influx through the voltage-dependent Ca-channel, and that in the K-contracture at the concentration of 100 mM-KCI, the mechanism of Na/ca exchange also partly contributs, in addition to the $Ca^{++}$ influx.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.6
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• pp.650-657
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• 2013

This study uses a muscle activation sensor and elbow joint model to develop an estimation algorithm for human elbow joint torque for use in a human-robot interface. A modular-type MVS (Muscle Volume Sensor) and calibration algorithm are developed to measure the muscle activation signal, which is represented through the normalization of the calibrated signal of the MVS. A Hill-type model is applied to the muscle activation signal and the kinematic model of the muscle can be used to estimate the joint torques. Experiments were performed to evaluate the performance of the proposed algorithm by isotonic contraction motion using the KIN-COM$^{(R)}$ equipment at 5, 10, and 15Nm. The algorithm and its feasibility for use as a human-robot interface are verified by comparing the joint load condition and the torque estimated by the algorithm.

• Journal of Korean Physical Therapy Science
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• v.9 no.3
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• pp.77-87
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• 2002

The purpose of this study was to compare the changes of muscle activities in deltoid with those in supraspinatus using electromyography(EMG) while subjects abducted their shoulder to different angles with different resistance. Methods : 20 volunteers who were comprised of 10 males(mean age: $21.2{\pm}2.0$) and 10 females(mean age: $20.2{\pm}1.6$) were collected. Surface electrodes were attached on deltoid and supraspinatus muscle for recording. Each reference electrode was located 3 cm to the each recording electrode. Muscle action potentials were recorded with changing the angle of shoulder abduction, $30^{\circ}$, $60^{\circ}$, $90^{\circ}$. This procedure was repeated with different resistance 0 pound, 2 pounds, 4.5pounds. The angle of shoulder abduction was determined by clinical goniometer. SPSS(Statistical Program for Social Science)/WIN 10.0 was used for statistics. Analysis included ANOVA, T-test. Results : The following results were obtained in this study. 1. There was significant differences during isometric shoulder abduction $30^{\circ}$, $60^{\circ}$, $90^{\circ}$ comparing muscle activity in deltoid and supraspinatus muscles at 0 pound, 2pound, 4.5pound resistance(p<0.05). 2. There was no useful significant in the deltoid and supraspinatus muscles activity EMG compared by physical condition. 3. Their was significant in the deltoid EMG compared by gender t=-5.41, P<0.01, but no difference in the supraspinatus EMG(P=0.333 >a=0.05). Conclusions: There are many previous studies on influence of shoulder angles and speeds of muscle activity. However most of them placed the focus on isotonic or isokinetic exercise, or shoulder function. But this study was done during isometric exercise, which is better for early assessment and treatment for injured patients. There is strong relationship between the shoulder angle with resistance in deltoid supraspinatus muscle activity. We conclude that it is important to apply isometric shoulder abduction exercise with correct angle and resistance especially in early stage.

• Journal of Convergence for Information Technology
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• v.10 no.10
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• pp.143-149
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• 2020

This study tried to observe the ability to inhibit vasocontriction in phloretin - the primary ingredient of apple tree leaves and the Manchurian apricot - through ROCK(Rho-associdated, coiled-coil containing protein kinase) inactivation in rat aortae. A piece of artery that was separated from Sprague-Dawley male rats and retained or damaged the endothelium was suspended in myograph tank with two metal rings, the lower ring fixed to the bottom of the tank, and the upper ring connected to the isotonic force transducer. Interestingly, phloretin inhibited fluoride- or phorbol ester-provoked contraction implying that additional pathways dissimilar from endothelial nitric oxide synthesis such as ROCK or MEK (mitogen activated protein kinase kinase) inactivation might be involved in the vasorelaxation. Therefore, this study provides that phloretin participates in the reduction of ROCK or MEK activity in smooth muscle in addition to the endothelial-dependent action of the endotheliuim in complete blood vessels, and consequently inhibits actin-myosin interaction in smooth muscle. Furthermore, phloretin inhibited thromboxane A2-induced contraction suggesting the mechanism including inhibition of ROCK and MEK.