• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3124-3132
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• 2011

Scott transformers have widely used to convert three phases into two phases and compensate the unbalance. Theoretically, the loads of the two secondary phases are same, no unbalance appears in the PCC(point of common coupling). But Due to the uncertainty of traction load, the unbalance are generally presented at the PCC. In this paper The amount of the voltage unbalance is expressed in the ratio of the negative sequence voltages to the positive sequence voltage. We tried to compensate the unbalance using SVC(Static Var Compensator）in an unbalance traction loads state by modeling. The SVC are installed and controlled to provide different amounts of reactive power compensation.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.801-803
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• 2001

On this study the motor design method with fairly good characteristics and control capability as well as cooling capability is presented with considering the magnetic effect due to ventilation hole, which is installed to prevent the temperature rise. When the input voltage rises due to critical variation in traction power supply system, the final ventilation hole is presented by checking the inductance parameter with clarifying the relation between saturation of the motor core and the ventilation hole.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.424-426
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• 1999

In this paper, the design characteristics, the manufacturing process and the results of performance test on the AC traction motor for urban transit standard E.M.U which is newly developed with applying standardization specification will be introduced. It is reviewed that the design and performance analysis on conventional motors considering system correlation and design constraint and the design optimization through an analysis of electro-magnetic, thermal and dynamic properties. The properties of factory products manufactured by 200 Class VPI process exhibit a excellent performance with a lower noise and vibration, higher efficiency and power factor etc.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.500-501
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• 2007

The method of maintenance in railway is going to be changed to improve reliability on traction equipment. Partial discharge (PD) tests are useful to evaluate the insulation condition of stator winding. This paper describes the use of PD tests with 5 model coils which have the defects such as internal, slot discharge. The PD tests are performed with epoxy-mica coupler 500 pF at various AC voltages. The result of test shows PD pattern can correlate with the species of defects on 5 model coils.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1035-1047
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• 2015

Starting from a new dynamic system description novel synchronous machine deterministic observers are proposed. Reduced and full order adaptive observer variations are presented. Based on the feedback linearization control law and the use of deterministic observer a novel control system is built. It meets the requirements of high performance tracking system. Adaptivity to stator and rotor resistance and the torque sensorless application is included. The comparison of the proposed novel control with conventional linear and nonlinear control systems is discussed. The given simulational study includes complete drive system integration.

• Proceedings of the KSR Conference
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• 1998.05a
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• pp.349-358
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• 1998

This study was carried out about the design and the performance study of propulsion system for Korean High Speed Train of maximum operating speed of 350km/h. The propulsion system was studied to two parts the formation of power transmission and the performance of traction system base on Korean-TGV. For maximum operating speed of 350km/h at Seoul-Pusan high speed line, the power of train should be have the remaining acceleration of 0.058m/s/s and the slopeability of 6%o. This performance study of propulsion system would be continued for defining of adhesion factor, friction factor and aerodynamic factor assumed to analysis and simulation.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.398-401
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• 2000

This paper describes the design of optimal location and capacity of DC substation for Mass Transit System. Three factors are considered for the design i.e. substation arrangements, line configuration and substation power capacity. In this study, we considered all of them for capacity calculation of power supply system for MTS. At first, DC-fed-traction system is introduced on an outline, a characteristics of train and fed network, and design method of substation arrangements. Optimal design procedures are described, and program for capacity calculation of the system is presented. In addition, the computer simulated results are compared with the conventional simple calculation method.

• Journal of Power Electronics
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• v.15 no.3
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• pp.841-848
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• 2015

As a vital part of renewable energy and electrical traction, power converters are supposed to have high reliability and good performance. However, power semiconductors produce considerable heat when the power converter works, which results in high junction temperatures that lower the reliability and performance of the power semiconductors. Many studies show that ambient humidity has a significant effect on power devices, but the influence of high humidity on junction temperatures has yet to be studied. Therefore, this paper presents a thermal model for power converters in moist air to obtain the junction temperature increase, which is utilized for the power converter used in a Switched Reluctance Motor System. Simulation results show that the law of converter temperature distribution is independent of the relative humidity in the case of fixed ambient temperature, whereas the temperature in the power converter decreases as the ambient relative humidity increases. These simulation results are validated with the experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2125-2130
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• 2010

The neutral section on electric railway system is significant sector in order to prevent short circuit of two electric powers. However, while electric trains pass the neutral section, those speed is decreased and the accident of AC electric traction system and the electric train would be occurred. So the countermeasures are urgently needed. The automatic power switching technology system that is current being research and development is system to improve these problems. Because main object of this system is power change using static switch in the neutral section, it's expected to cause a variety of transients. Especially, onboard transformer inrush current for electric railway train can be occurred more than rated current according to switching time. Therefore, the analysis and improvement are needed to ensure the stability of this system. In this paper, we analyze the operating characteristics of the automatic power switching technology system. Especially, it reviews inrush current according to the closing phase angle. And we propose control plan of inrush current considering the case that voltage is maintained due to counter electromotive force and regenerative braking operation of electric railway train. Finally, the proposed control scheme was reviewed using the transient analysis program.

• Korean Journal of Agricultural Science
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• v.49 no.4
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• pp.845-855
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• 2022

The purpose of this study is to develop a self-propelled underground crop harvester and its performance was evaluated by measuring the load during actual potato harvesting operations. This study was conducted at a constant working speed of 1 km·h^-1. A load measurement system was installed to measure the actual load and the required working power was analyzed. A hydraulic pressure sensor was also installed to measure the hydraulic pressure. The required hydraulic power was calculated using the hydraulic pressure and flow rate. The results showed that the engine speed, torque, and power during harvesting operation were in the range of 845 - 1,423 rpm, 95 - 228 Nm, and 9 - 31 kW, respectively. Traction power, excluding the hydraulic pump of the tractor and power take-off (PTO) output, was in the range of 9 - 28 kW, and it was confirmed that it occupies a ratio of 16.2 to 50% of the engine rated output. The engine can supply the minimum required traction power to move the vehicle. This means that the engine used in this study could be down-sized to be suitable for an underground crop harvester. In this study, the gear stages of the tractor were not considered. This research thus shows the possibility of developing a self-propelled underground crop harvester.