• Journal of Power Electronics
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• 제17권2호
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• pp.368-379
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• 2017

In this paper, a direct torque control algorithm with novel duty cycle-based modulation is proposed for permanent magnet synchronous motor drives fed by neutral-point clamped three-level inverters. Compared with the standard DTC, the proposed algorithm can suppress steady-state torque ripples as well as ensure neutral-point potential balance and smooth vector switching. A unified torque/flux evaluation table with multiple voltage vectors and precise control levels is established and used in this method. This table can be used to evaluate the effects of duty-cycle vectors on torque and flux directly, and the elements of the table are independent of the motor parameters. Consequently, a high number of appropriate voltage vectors and their corresponding duty cycles can be selected as candidate vectors to reduce torque ripples by looking up the table. Furthermore, small vectors are incorporated into the table to ensure the neutral-point potential balance with the numerous candidate vectors. The feasibility and effectiveness of the proposed algorithm are verified by both simulations and experiments.

• 대한통합의학회지
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• 제1권2호
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• pp.47-57
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• 2013

Purpose : The purpose of this study was to compare the Effects of Knee Extensor, Flexor Muscle Strength and Joint Position Sense in Squat Exercise on Variety Surface. Method : Subjuects were consisit of 30 male and female who had non disorder knee joint. we had devided 3 group(control group, balance pad group, and togu group) and we measured that knee joint $15^{\circ}/45^{\circ}$proprioception(position sense) and Peak Torque of knee extensor, flexor muslce at $60^{\circ}/sec$, $180^{\circ}/sec$ angular velocity. Result : First, knee joint $15^{\circ}$proprioception(position sense) of balance pad and togu group was significantly different after exercise(p<.05), but only balance pad group was significantly different at knee joint $45^{\circ}$. Second, knee extensor Peak Torque of balance pad and togu group was significantly different at $60^{\circ}/sec$, $180^{\circ}/sec$ angular velocity(p<.05). Third, knee flexor Peak Torque of balance pad and togu group was significantly different at $60^{\circ}/sec$, $180^{\circ}/sec$ angular velocity(p<.05). Conclusion : Squat exercises on the balance pad and togu were affects knee joint proprioception and muscle strength improvement. These results suggest that squat exercise on the unstable surface is effective for prevention of knee joint injury and functional activity.

• 한국신뢰성학회지:신뢰성응용연구
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• 제13권1호
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• pp.11-18
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• 2013

For a reliability assessment of machinery parts, accurate performance test, environmental test, life test, etc. are required on the sample. In the performance test conditions of various machinery parts, some problems happen such as needs to rise temperature rapidly with large flow of oil having very low thermal conductivity and to measure very high torque or tiny torque, etc. This study brings out the method to apply heat to rise temperature for large flow of oil without chemical change in a performance test of oil cooler. To measure large scale of torque in a performance test of planetary gearbox of excavator, the method of torque measurement is proposed by replacing the large torque meter priced very expensive. To measure very small torque on lubricated friction, a methode of force balance type test mechanism is introduced for tests of piston assembly.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.801-806
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• 2008

Large quantity of bending deformation as well as rotating torque fluctuation at the balance shaft are main struggles during the operation in a high speed rotation and thereby, two issues should be cleared at the design process of balance shaft module. Since two issues are highly related with balance shaft itself and particularly much sensitive to the location of both supporting bearing and unbalance mass, the design strategy on balance shaft should be investigated at the aspect of controlling two critical issues at the early stage of balance shaft design. To tackle two main problems, the formulation of objective function that minimizes critical issues, both bending deformation as well as torque fluctuation, is suggested to derive the optimal information on balance shaft. Then, optimal informations are reviewed at the practical logics and the guideline at the selection of locations, both supporting bearing and unbalance mass, is addressed at the final chapter.

• 한국운동역학회지
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• 제21권4호
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• pp.411-420
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• 2011

The purpose of this investigation was to determine whether correlations exist between balance and impact velocity, angular position, and maximum velocity of a club during drive swing. Twelve skilled golfers were recruited in this study. They were asked to perform ten swing trials and two trials were selected for analysis. Balance parameters were calculated via the force platform while kinematic variables were determined by using the Qualisys system. The results of the present study demonstrated that the average of COP velocity was faster in the medio-lateral direction rather than the anterio-posterior direction. Also, left foot's COP velocity and free torque were greater than the right foot's before impact. The range of the right foot's COP in the anterio-posterior direction before impact were correlated with the club velocity and angular position at impact. There was a negative correlation between the left foot's COP velocity before the impact and the velocity at impact. Additionally, the range and RMS of the left foot's free torque affected on the club angular position at impact and the maximum velocity at release, respectively. Finally, a negative correlation existed between the range of the right foot's free torque after the impact and club's maximum velocity at release.

• 한국소음진동공학회논문집
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• 제18권3호
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• pp.277-283
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• 2008

Balance shaft module contributes to reduce the engine-born vibration by compensating it from a unbalance mass with opposite phase but practically, this device has some problems during the operation in a high speed owing to the considerable amount of unbalance mass that leads to the large quantity of bending deformation as well as torque fluctuation at the balance shaft. To tackle two main problems, the design strategy on balance shaft is suggested by addressing the optimal location of unbalance mass and supporting hearing based on the formulation of objective function that minimizes critical issues, both bending deformation as well as torque fluctuation. The boundary condition of balance shaft assumes to be free such that any external force or contact component is not taken into consideration in this study.

• The Journal of Korean Physical Therapy
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• 제27권6호
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• pp.392-399
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• 2015

Purpose: This study investigated whether the strength imbalance between two muscles can affect the score of EMG based biofeedback game, and whether the EMG based biofeedback game score can be used as predictable indicator of the degree of muscle balance alternating the conventional strength measuring equipment. Methods: 40 participated in this study. Biodex was used to measure the peak torque/weight in order to calculate the muscle strength balance index between plantar flexor and dorsiflexor of ankle joint. And muscle balance index (MBI) was calculated. The EMG biofeedback game scores of dorsiflexor and plantar flexor were acquired, so that the EMG electrodes were attached at tibialis anterior and gastrocnemius. The relationship between the game score and the muscle balance index were analyzed. Results: There was negative correlation between the muscle balance index between plantar flexor and dorsiflexor and the peak torque/weight of plantar flexor (r=-0.70). And there was negative correlation between the muscle balance index between plantar flexor and dorsiflexor and the game score of plantar flexor (r=-0.83). Conclusion: The EMG biofeedback game score had significant relationship with muscle imbalance at ankle joint, so it seems that the game score can be used for predicting the degree of muscle imbalance as a parameter.

• The Journal of Korean Physical Therapy
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• 제27권6호
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• pp.386-391
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• 2015

Purpose: This study investigated whether the strength imbalance between two muscles can affect the score of EMG based biofeedback game, and whether the EMG based biofeedback game score can be used as predictable indicator of the degree of muscle balance alternating the conventional strength measuring equipment. Methods: 40 participated in this study. Biodex was used to measure the peak torque/weight in order to calculate the muscle strength balance index between plantar flexor and dorsiflexor of ankle joint. And muscle balance index (MBI) was calculated. The EMG biofeedback game scores of dorsiflexor and plantar flexor were acquired, so that the EMG electrodes were attached at tibialis anterior and gastrocnemius. The relationship between the game score and the muscle balance index were analyzed. Results: There was negative correlation between the muscle balance index between plantar flexor and dorsiflexor and the peak torque/weight of plantar flexor (r=-0.70). And there was negative correlation between the muscle balance index between plantar flexor and dorsiflexor and the game score of plantar flexor (r=-0.83). Conclusion: The EMG biofeedback game score had significant relationship with muscle imbalance at ankle joint, so it seems that the game score can be used for predicting the degree of muscle imbalance as a parameter.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권1호
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• pp.38-44
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• 2003

In this study, the balance beam control subsystem, new type of construction machinery using the mechanism of CMG (control moment gyro), for the attitude control of an unstructured object such as a beam carried by a tower crane, is designed and implemented. The balance beam controller consists of a wheel spinning at high speed and an outer gimbal for controlling the attitude of the wheel. Two motors, one for the wheel and the other for the gimbal, are used. Applying force to the spin axis of the wheel, as an input of the system, leads the torque about the axis because of the gyro effects. This torque is used to control the attitude of the unstructured object in this study. For the stabilizer function, in addition, holding the load at the current position, the attitude of the wheel is freed by cutting the power applied to the gimbal motor of the balance beam controller, which result in the braking force to stop the load by gyro effect. The works presented here include the mechanical system of the balance beam controller, the remote controller, the servo controller and the control software for the system. We also present experimental results to show that the system we proposed is useful as a new construction machinery which can control the attitude of the beam hanging from a tower crane.

• 제어로봇시스템학회논문지
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• 제21권4호
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• pp.301-308
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• 2015

In this paper, we propose an LTBC (Low Tension and Load Balance Control) scheme to improve a coiling shape control by reduction the tension fluctuation by the torque disturbance in the down coiler process of hot strip mills. The proposed controller is a combination of an LTC to control the overload at load-on in the mandrel and an LBC to regulate the load balance of the upper and bottom pinch roll. A tension calculation model is suggested with the concept of the tension deviation. The effectiveness of the proposed control scheme is verified from simulation under a disturbance of the pinch roll torque. Using a field test, we show that the performance of the shape and tension control is improved by the LTBC control.