• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.4
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• pp.206-213
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• 2012

This paper propose a improved speed control system for five-phase squirrel-cage induction motor(IM) considering effects of 3rd. harmonic current components with field oriented control(FOC) A five-phase IM drives present unique characteristics due to the additional degrees of freedom and also drives possess many others advantage compared with the traditional three-phase motor drive system, such as reducing a amplitude of torque pulsation at low frequency and increasing the reliability. In order to maximize the torque per ampere, the proposed motor has concentrated windings. The produced back-electromotive force is almost trapezoidal, and the motor is supplied with the combined sinusoidal plus third harmonic of currents. There is necessary to controlled 3rd harmonic current. For presenting the superior performance of the proposed the speed control system, experimental results are presented using a 32-bit fixed point TMS320F2812 DSP with 1.5[KW] induction motor.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.977-980
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• 1993

The technique to design high performance small motors has been based on experimental data, which results from lots of cost, experience and time in manufacturing. Recently, as high-performance computer appears, many engineers use numerical methods to design and analyze electric machine. Since, the step motor which has very small air gap(0.02-0.05mm) is different from other electric machine in its structure. The shape of rotor teeth and stator teeth influence seriously on the torque characteristics. And it is operated over magnetic saturation point. Therefore, the design of step motor needs to solve nonlinear problem and to calculate magnetic field precisely. In this paper, we solve nonlinear problem by employing Finite Element Method and obtain torque-displacement characteristics for the design of step motor. We also manufacture VR step motor according to the obtained results, and measure some torque characteristics. Through comparing calculated results with experimental results, it is verified that FEM is very useful to design step motor, and the motor designed by our technique is improved in its step accuracy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.4
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• pp.748-757
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• 2007

This paper is intended to solve the technical problem that fails in large-capacity induction motor starting due to serious voltage drop during starting period. One induction motor that is established already can reach in steady-state using reactor starting method but the voltage magnitude of PCC (point of common coupling) has dropped down a little. When the same capacity induction motor is installed additionally in the PCC, where the existing induction motor is operating, voltage drop becomes more serious by starting of additional induction motor. As a result, the additional induction motor fails in starting. Therefore, voltage compensation method is proposed so that all of two induction motors can be started completely. First, modeling technique is described in order to implement starting characteristics of large induction motor. And then, this paper proposes strategic starting scheme by proper voltage compensation that use no-load transformer tap control (NLTC) and step voltage regulator (SVR) for starting of two large induction motors successfully and improving the feeding network voltage profile during the starting period. The induction motor discussed in this paper is the pumped induction motor of 2500kVA capacity that is operating by KOWACO (Korea Water Resources Corporation). Modeling and simulation is conducted using PSCAD/EMTDC software.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.11
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• pp.1528-1534
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• 2013

This paper proposes the optimal design of stator shape for cogging torque reduction of single-phase brushless DC (BLDC) motor with asymmetric notch. This method applied size and position of asymmetric notches to tapered teeth of stator for single-phase BLDC motor. Which affects the variation of the residual flux density of the permanent magnet. The process of optimal design included the extraction of the sampling point by using Latin Hypercube Sampling(LHS), and involved the creation of an approximation model by using kriging method. Also, the optimum point of the design variables were discovered by using the Genetic Algorithm(GA). Finite element analysis was used to calculate the characteristics analysis and cogging torque. As a result of finite element analysis, cogging torque were reduced approximately 39.2% lower than initial model. Also experimental result were approximately 38.5% lower than initial model. The period and magnitude of the cogging torque were similar to the results of FEA.

• Journal of Korean Medicine Rehabilitation
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• v.21 no.3
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• pp.45-55
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• 2011

Objectives : The main purpose of this study is to investigate the efficacy of Kyejibokryong-whan(Guizhifuling-wan) and examine the blood stasis for patients with motor vehicle accident. Methods : Of the patients who have visited Dong-Shin university oriental hospital for general pan due to motor vehicle accident from June 2010 to November 2010, we enrolled 29 patients and performed blood stasis diagnosis. Patients were divided into groups according to blood stasis findings. Patients who had more than twenty blood stasis diagnosis point were classified as blood stasis group. Patients who had under twenty blood stasis diagnosis point were classified as non blood stasis group. We administered Kyejibokryong-whan(Guizhifuling-wan) to all group. The effect was assessed by VAS(visual analogue scale), SF-MPQ(short form-McGill pain questionnaire) ODI(Oswestry disability index) & NDI(neck disability index). Results : The pain & function index decreased in both groups after treatment. Conclusions : The difference between blood stasis group and non blood stasis group were not significant at after treatment stage. This data suggested that the method of classifying blood stasis is useful and the Kyejibokryong-whan(Guizhifuling-wan) can be effective means that decrease pain caused by motor vehicle accident.

• Physical Therapy Rehabilitation Science
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• v.11 no.1
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• pp.8-15
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• 2022

Objective: Post stroke motor recovery is facilitated by the brain reorganization or the neuroplastic changes. The therapeutic approach mentioned in the current case is one of the approaches for enhancing motor recovery by stimulating the damaged neural networks directing the motor behaviour of a person. The aim of the present study was to establish the changes in the balance and gait pattern of an individual through multi target stimulation of areas of cerebral cortex by utilising multichannel trans cranial direct current stimulation (M-tDCS) in a sub-acute stroke survivor. Design: A Case Report Methods: The present patient was the participant of the trial (CTRI/2021/02/031044).The patient was intervened with M-tDCS (anodes over left primary motor cortex that is C3 point and left dorsolateral prefrontal cortex i.e., F3 point and cathodes over supraorbital areas, Intensity - 1.2mA) for the duration of 20 minutes along with turbo med extern - an AFO to facilitate ankle dorsi flexion and conventional physiotherapy rehabilitation. The Fugl-Meyer assessment lower extremity (FMA-LE), Berg Balance Scale (BBS), Wisconsin Gait Scale (WGS) and the Stroke Specific Quality of Life (SSQOL) measures were used for outcome assessment. Baseline assessment was done on day 0 followed by assessment on 10 and 20 post intervention. Results: Improvement was seen in all the tools i.e. (FMA -LE), BBS, SSQOL and WGS over the time period of 20 days. Conclusions: M-tDCS resulted in improvement in gait parameters, balance and motor functions of lower extremity of the patient.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.2
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• pp.193-199
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• 2015

This paper proposes a regeneration braking algorithm for Brushless DC (BLDC) motor system. The unipolar switching method has a limitation about the regeneration braking when the BLDC motor is operated in the low speed region. The proposed algorithm alternatively utilizes the unipolar and bipolar switching method to implement the regeneration braking for overall speed range. The bipolar switching method is used when the BLDC motor is operated in the low speed region. The switching transition point is determined by analyzing the unipolar and bipolar switching during the regeneration braking. The effectiveness of proposed algorithm is verified by using the experimental results.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.889_890
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• 2009

Design of high efficiency Switched Reluctance Motor (SRM) for Low Speed Electric Vehicle (LSEV) is presented in this paper. The design is made from point of view to save more used energy for operating LSEV. Focus on saving the energy gives more efficiency can be produced. Based on applying suitable driving cycles and investigates the frequently power used are foundation to design the proposed motor. Meanwhile through Finite Element Analysis (FEA) characteristic of the proposed motor such as inductance and torque profile can be obtained.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1115-1119
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• 2007

Five control methods (Speed Control, PID Gain Scheduling, Loop Time Control, Simple PID, Switching Control) have been applied to the control of an Inline Co-axial valve by the simulation of AMESim. The simulation results have shown that the speed control method is the most stable and the fastest way to reach to the set point in the simulation of the flow control. Moreover, It has been found that the five control methods have the almost same characteristics in the power consumption, the counter electromotive force, and the motor angular velocity. According to the analysis results, the fast and stable control characteristics of the speed control method is the most suitable for the flow control using a inline co-axial valve with a DC(BLCD) motor.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.9
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• pp.84-89
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• 2006

This paper presents the thickness effect of hysteresis ring of hysteresis motor using finite element method combined with a vector hysteresis model. From the magnitude and direction of the magnetic field intensity, the magnetization of each ring element is calculated by a vector hysteresis model. The developed torque can be obtained with the vector sum of individual torque of each element on the hysteresis ring. From these calculations, it can be found that the motor torque is not in proportion to the thickness of the ring. As a result, there exists a proper point of thickness and that can be determined using the proposed methoㅇ in this paper.