• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.838-840
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• 2002

Most adjustable-speed drives (ASDs) designed to operate 220[V] induction motors incorporate voltage-source inverters (VSIs), which create motor voltages at high switching frequencies. The motor leads used to connect an ASD to a motor can behave like transmission lines for voltage pulses, which can be reflected at the motor terminals. The resulting oscillatory transient, known as the long-lead effect, can stress and consequently degrade the stator insulation system of a motor. This paper describes the results of tests to 1) determine the correlation between peak motor voltage and the length of motor leads and 2) determine the correlation between peak motor voltage and the switching frequency of the ASD

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.918-923
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• 2011

On AC railway systems, the neutral sections are installed in front of substations and sectioning posts in order to avoid crash between power that have differing phases. In case railway vehicles pass through these neutral sections, it is necessary for them to switch to coasting driving by notch-off. This may reduce speed of the vehicles, resulting lowered train operation efficiency. The usage of automatic power switching systems makes it possible to pass neutral sections at notch-on, enhancing operation efficiency so that it is appropriate for high-speed railway applications. This paper introduces a simulator that assesses efficiency of automatic power switching systems in neutral sections. The is composed of a power supply system, electric railway vehicles, thyristor switches, and traction motors.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.190-198
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• 2002

In switched reluctance motor(SRM) drive, it is necessary to synchronize the stator phase excitation with the rotor position. Therefore the rotor position information is an essential. Usually optical encoders or resolvers are used to provide the rotor position information. These sensors are expensive and are not suitable for high speed operation. In general, the accuracy of the switching angles is dependent upon the resolution of the encoder and the sampling period of the microprocessor. But the region of high speed, switching angles are fluctuated back and forth from the preset values, witch are cause by the sampling period of the microprocessor. Therefore, the low cost linear encoder suitable for the practical and stable SRM drive is proposed and the control algorithm to provide the switching signals using the simple digital logic circuit is also presented in this paper It is verified from the experiments that the proposed encoder and logic controller can be a powerful candidate for the practical low cost SRM drive.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.482-484
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• 1994

In this paper, to realize high speed position control of LDM (Linear DC Motor), the minimum time control method is applied. But, In this control method, calculation of non-linear function is required Therefore, in order to avoid this complex calculation, optimum switching of the Bang-Bang control is done on parabola type switching function established in the plane of phase. But, the sliding mode is occurred due to the modeling error of LDM and the variation of parameters. Thereby, the optimum 'control is not realized. In order to realize optimum control, the algorithm to modify switching function is proposed

• Journal of Korean Society for Quality Management
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• v.33 no.3
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• pp.71-90
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• 2005

New high-speed rail service, the Korea Train Express(KTX), has been beginning service in Korea. We measured the service quality of the Korea Train Express and comparatively analyzed the service quality of domestic flight and express buses which are means of long distance transportation. Furthermore, by using the Kano model, the perception level of the service of customers is not only segmented in groups but also switching barriers are derived. As a result, the customers by group have a difference in the level of their perception. While in both high-speed bullet train service and flights dimensions significantly affect the customer satisfaction and retention excluding a responsiveness dimension, in the Train Express four dimensions(Reliability, Responsiveness, Assurance, Tangibles) with the exception of Empathy which significantly affect the customer satisfaction and retention.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.239-243
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• 2004

This paper presents a proper switching angle calculation method of Switched Reluctance Motor (SRM) for drill. The characteristic of SRM drive is very related to the scheduling of commutation angle and current waveforms. Therefore, a selection method of switching turn-on and turn-off angle is suggested for adaptational operation of SRM with varied rotor speed and load. Simulation and experimental results are presented for the validation of proposed method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.8
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• pp.1269-1275
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• 2002

This paper presents a new method for removing reaching phase in variable structure control systems using Bell type switching function. By proposed method, during the entire control process reaching phase is removed. For effective speed control of trapezoidal type brushless DC motor, a time varying switching function based speed controller is developed as illustration.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.163-166
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• 2001

Software controlled traffic management becomes more difficult with increasing switch size, because a huge number of connections are multiplexed in a high speed switching system and each ATM connections does not have a fixed bandwidth It is based on high-speed WDM(wavelength division multiplexed) links that can multiplex a huge number of connections on a statistical basis, and a self-load balancing technique. the Proposed switching system is scalable, and achieves the non-blocking capability without the use of complicated software control, using instead a hardware self-load balancing mechanism

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1779-1780
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• 2008

This paper presents a switching system of speed controller between PI (Proportional_Integrator) and P_LPF (Proportional_Low pass filter) to improve overshoot and slow settling time in DC motor. When the integrator is saturated in the PI controller, the error signal is integrated continuously. For preventing the state, the Anti-windup scheme is proposed. But the Anti-windup scheme dose not show stable characteristics in the whole speed command section after tuned a gain. By using P_LPF switching system these problems are improved and there is no need to tune of user hereafter, when the integrator is saturated. The proposed method is verified by the simulation results using MATLAB SIMULINK.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1182-1187
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• 2008

In this research, studied were performance improvements of the power conversion system for the high speed EMU. The object of this research is separated into two parts ; the one is the analysis of the designed transformer and the other is the switching improvement of a parallel PWM converter. The multi-outputs of a transformer must be balanced. However, the output of transformer is interfered and unbalanced in practical operation. To solve these problems, the electromagnetic analyzing model of a transformer is used to minimize the output interference. Also, the improvement of converter switching can reduce the unbalanced output and harmonics.