• Herbal Formula Science
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• v.25 no.4
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• pp.499-508
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• 2017

Objectives : Skeletal muscle atrophy occurs in response to a variety of conditions. The unloading to muscle occurs clinically in limb immobilization, bed rest, spinal cord injury and peripheral nerve damage, resulting in significant loss of muscle mass and force production. Muscle disuse is accompanied by an increase in apoptotic signaling, which mediates some of the responses to unloading in the muscle. In this study we tested the hypothesis that Daeyeoung-jeon extract would improve muscle recovery after reloading following disuse. Method : Twenty young male Sprague-Dawley rats were used for the studies. The hindlimb immobilization was performed with casting tape to keep the left ankle joint in a fully extended position. No intervention was performed on the right leg and used as intact region. The Rats in Daeyeoung-jeon treated group (DYJ) were orally administrated Daeyeoung-jeon water extract, and rats of Control group were given with saline only. After 2 weeks of immobilization, all animals were sacrificed, and the whole gastrocnemius muscles were dissected from both legs. The morphology of right and left gastrocnemius muscles in both DYJ and Control groups were assessed by hematoxylin and eosin staining. Moreover, to investigate the immobilization-induced muscular apoptosis, the immunohistochemical analysis of Bax and Bcl-2 was carried out. Results : Daeyeoung-jeon represented the significant protective effects against the reductions of the left gastrocnemius muscles weight and average cross section area to compared with Control group. The treatment with Daeyeoung-jeon extract significantly reduced the immunoreactivity of BAX and increased the immunoreactivity of Bcl-2 in gastrocnemius muscle compared with Control group. Conclusion : Daeyeoung-jeon has protective effects against immobilization-induced muscle atrophy by regulating the activities of apoptosis-associated BAX/Bcl-2 proteins in gastrocnemius muscle.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.9
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• pp.799-804
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• 2015

The purpose of this study is to analyse the dynamic disturbances(disturbed forces and disturbed torques) due to attitude control thruster's plume impingement on the solar arrays. To produce database of the dynamic disturbances a sweep analysis was done, in which the two parameters are used; the distance between the thruster and solar arrays and the thruster tilt angle. Based on the database, a third order polynomial approximation is computed to represent the characteristics of the disturbed forces and torques. The final results are the coefficients of the approximation for each solar array angle position. These results as input data are used to optimize the configuration of the attitude control thrusters. This analysis is appled to the two candidate solar arrays for Geo-Kompsat-2 satellite and the results of the disturbed forces and disturbed torques are compared and analysed.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.2
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• pp.105-110
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• 1990

In this paper, a compliance robot control algorithm using a PID adaptive controller is proposed. The compliance robot is suitable for the tasks in contact with environment, such as assembly operation or surface processing. A hybrid robot control method can control force and position simultaneously and two independant feedback closed loops are formed in this method. Because the compliance robot is operated in contact with environment, it is very difficult to obtain linear model of dynamics for this robot. In order to overcome this difficulty, a PID adaptive controller independant of robot dynamics is applied to the compliance robot. The proposed control algorithm for the compliance robot was analyzed and conformed by simulating the surface processing task by a two-joint robot.

• Physical Therapy Korea
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• v.19 no.2
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• pp.39-47
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• 2012

The purpose of this study is to examine the influence of a horse riding simulator and galvanic vestibular stimulation on improving the ability to balance posture and proprioception. Thirty healthy adults participated and were randomly assigned to a horse riding simulator group ($n_1$=10), galvanic vestibular stimulation (GVS) group ($n_2$=10), control group ($n_3$=10). Experiment groups were trained 3 times per week over 6 weeks. The ability to balance posture was measured by force plate and proprioception was measured by Joint position sense. The following results were obtained. the changes of balance index were significant interaction in each group in accordance with the experiment time in 0, 3 and 6 weeks (p<.05). All groups showed the most decreasing pattern compared with the control group. But was not statistically significant. Proprioception was significant interaction in each group in accordance with the experiment time (p<.05). All groups showed the most decreasing pattern compared with the control group. The above results indicated that the 6 weeks horse riding simulator and galvanic vestibular stimulation training demonstrated positive effects in the ability to balance posture and proprioception. These results suggest that the horse riding simulator and galvanic vestibular stimulation training could be therapeutic intervention that can improve balance and postural control.

• Korean Journal of Applied Biomechanics
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• v.28 no.4
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• pp.213-218
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• 2018

Objective: The purpose of this study was to examine the effect of the core muscle strength enhancement of the elderly on 8 weeks training using the core exercise equipment for the elderly on the ability to control the whole-body center of mass in posture stabilization. Method: 16 females (10 exercise group, 6 control group) participated in this study. Exercise group took part in the core strength training program for 8 weeks with total of 16 repetitions (2 repetitions per week) using a training device. External perturbation during standing as pulling force applied at the pelvic level in the anterior direction was provided to the subject. In a UCM model, the controller selects within the space of elemental variables a subspace (a manifold, UCM) corresponding to a value of a performance variable that needs to be stabilized. In the present study, we were interested in how movements of the individual segment center of mass (elemental variables) affect the whole-body center of mass (the performance variable) during balance control. Results: At the variance of task-irrelevant space, there was significant $test^*$ group interactions ($F_{1,16}=7.482$, p<.05). However, there were no significant main effect of the test ($F_{1,16}=.899$, p>.05) and group ($F_{1,16}=1.039$, p>.05). At the variance of task-relevant space, there was significant $test^*$ group interactions ($F_{1,16}=7.382$, p<.05). However, there were no significant main effect of the test ($F_{1,16}=.754$, p>.05) and group ($F_{1,16}=1.106$, p>.05). Conclusion: The results of this study showed that the 8 weeks training through the core training equipment for the elderly showed a significant decrease in the $Vcm_{TIR}$ and $Vcm_{TR}$. This result indicates that the core strength training affects the trunk stiffness control strategy to maintain balance in the standing position by minimizing total variability of individual segment CMs.

• Tribology and Lubricants
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• v.36 no.5
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• pp.253-261
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• 2020

In this paper, we present an experimental investigation of the frequency characteristics and a visual inspection of an oxidizer pump with a modified rear-floating ring seal for a 7-tonf turbopump. An oxidizer pump typically operates at high rotational speeds and under cryogenic conditions. Despite its low hydraulic efficiency, the floating ring seal is frequently employed as a leakage control solution for turbomachinery because it effectively reduces abrasion by friction. When the oxidizer pump starts up, the floating ring moves excursively but locks up stably against the pump casing when the contact pressure increases. The compressive force on the floating ring depends on the hydrodynamic forces induced by the flow through the floating ring. This force is controlled by the nose position of the floating ring. Based on a validation test for a 7-tonf turbopump with two types of floating rings, we concluded that the floating ring with a small diameter nose can move easily with a low contact pressure in the cooling path. This leads to instability of the pressure fluctuation around the floating ring. In contrast, a floating ring with a large diameter nose has a high contact pressure and attaches strongly to the casing, which causes wear and frictional oxidation between the contact surfaces of the impeller and the floating ring.

• Progress in Medical Physics
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• v.32 no.4
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• pp.153-158
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• 2021

Purpose: This study evaluated the features of a pressure mapping system for patient motion monitoring in radiation therapy. Methods: The pressure mapping system includes an MS 9802 force sensing resistor (FSR) sensor with 2,304 force sensing nodes using 48 columns and 48 rows, controller, and control PC (personal computer). Radiation beam attenuation caused by pressure mapping sensor and signal perturbation by 6 and 10 mega voltage (MV) photon beam was evaluated. The maximum relative pressure value (mRPV), average relative pressure value (aRPV), the center of pressure (COP), and area of pressure distribution were obtained with/without radiation using the upper body of an anthropomorphic phantom for 30 minutes with 15 MV. Results: It was confirmed that the differences in attenuation induced by the FSR sensor for 6 and 10 MV photon beams were small. The differences in mRPV, aRPV, area of pressure distribution with/without radiation are about 0.6%, 1.2%, and 0.5%, respectively. The COP values with/without radiation were also similar. Conclusions: The characteristics of a pressure mapping system during radiation treatment were evaluated on the basis of attenuation and signal perturbation using radiation. The pressure distribution measured using the FSR sensor with little attenuation and signal perturbation by the MV photon beam would be helpful for patient motion monitoring.

• The korean journal of orthodontics
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• v.22 no.2 s.37
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• pp.345-372
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• 1992

The purpose of this experiment was to study the effects of changes of mandibular position on temporomandibular joint in internal derangement patients Twenty-four female New Zealand White Rabbits, weighing over 3.5kg, were utilized in this study . Bilateral temporomandibular joint surgery was performed in twenty-one of the rabbits to displace disc anteriorly through incising the retrodiscal tissue 1-2mm posterior to the disc, thus inducing internal derangement. They were divided into three groups nine were left untreated after surgery, six were fitted with functional protrusive appliances 4 weeks after surgery, and six wore collar appliances to apply 4 ounces of mandibular refractive force per side 4 weeks after surgery. The remaining three served as the control group. Histologic examinations were performed after sacrificing them by threes at 4-week intervals. The results were as follows. 1. Histologic findings similar to internal derangement were observed in the rabbits whose retrodiscal tissues had been incised. 2. In the rabbits untreated after surgery, articular surface on condylar process and articular eminence showed severe erosion and deformation, and displaced disc manifested changes in both shape and internal architecture. 3. Functional protrusion after surgery resulted in progressive remodeling on postero-superior portion of condyle and glenoid fossa, while it also brought about erosion on articular eminence and anterior portion of condyle. 4. Mandibular retraction after surgery resulted in compression of retrodiscal tissue and regressive remodeling of posterior portion of condyle.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.2
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• pp.16-23
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• 2018

Postural instability can increase the likelihood of hazardous slip and fall accidents in workplaces. The present study intended to extend understanding of the effect of abnormal neck posture on postural control during quiet standing. The effect of body fatigue on the postural control was also of primary concern. Twelve healthy undergraduate students volunteered to participate in the experiment. Standing on a force platform with the neck neutral, flexed, extended, or rotated, subjects' center of pressures (COP) were measured under the two levels of body fatigue. For the fatigue condition, Subjects exercised in a treadmill to meet the predetermined level of body fatigue. Analyzing the position coordinates of COPs, the length of postural sway path was assessed in both medio-lateral (ML) axis and anterior-posterior (AP) axis. Results showed that, in AP direction, neck extension or rotation significantly increased the sway length as compared with neck neutral. Neck extension led to greater sway length compared to neck rotation. Neck flexion did not differ from neck neutral. The sway length in the AP direction also became significantly larger as the body fatigue accumulated after treadmill exercise. In ML direction, as compared to neutral posture, the neck extension, flexion, or rotation did not significantly affect the length of postural sway path. However, the sway length seemed to increase marginally with the neck extended during the fatigued condition. This study demonstrates that abnormal neck posture may interfere with postural control during standing. The ability to maintain postural stability decreases significantly with the neck extended or rotated. Body fatigue leads to postural instability further.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.5
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• pp.452-459
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• 2020

The electric actuator receives the user's command input signal (open/closed/stop), checks the status of various sensors (valve position, rotational force, motor status, etc.)in the actuator, and controls the motor forward/reverse to open and close the valve. It is a device that outputs the current state of an actuator (valve) and is used in various fields such as dams, power plants, water and sewage facilities, and oil pipeline facilities. If an electric actuator is installed in a power plant and a problem occurs during operation, it can cause a large economic loss, so system reliability is vert important. In this study, in order to increase the safety of the electric actuator, the development of an electric actuator control device capable of setting the ON/OFF time in hardware was conducted to solve the reliability problem that may occur in software. In addition, the electric actuator control device development environment was developed using Xilinx's Spartan7 FPGA and Altium tool.