• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.699-701
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• 2000

It leaves much room for improvement that UTM-01 is of practical use. Therefor we will design of UTM-02 system. The design of new magnet is based on light weight for bogie system. We used Maxwell-3D FEM for design of new magnet. The new magnet for UTM-02 that was reduced weight of magnet. 22kg, then it was increased ratio lift to weight is 9.87.

• Proceedings of the KIEE Conference
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• 2005.07e
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• pp.46-48
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• 2005

Wind-induced oscillations are known to cause damage to the conductors and related hardware through fatigue, clashing of the bundled conductors and bolt loosening. Wake-induced oscillations have been known since the advent of bundled conductors. they are caused by aerodynamically unstable forces acting on the leeward conductors in the wake of the windward conductors, In order to control it, spacer dampers are installed in transmission lines with bundled conductors. Spacer damper installation is very important, it can cause damage to the conductors and spaer damper itself. This paper suggests importance of spacer damper installation in bundled conductor systems.

• Proceedings of the KIEE Conference
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• 2005.07e
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• pp.88-90
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• 2005

There are a lot of troubles during the transfer of the source of electric power in UPS (uninterruptible power supply system) which is indispensable to the industrial equipments. They cause blackout accidents, resulting in a great economic loss. After measuring and analyzing the transient phenomena happening during the transfer, this paper presents the solution of the troubles. The solution can be used as a basic material for maintenance and it can minimize the troubles occurring in UPS and enhance the reliability of it.

• 전기의세계
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• v.17 no.1
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• pp.11-20
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• 1968

A typical type-1 positioning servomechanism is theoretically analyzed as a multirate sampled-data system which contains two or more signals sampled at different rates by the Z-transform method. And also it is analyzed as a continuous system by using the Younsei 101 Electronic Analog Computer. Comparing the solution of the multirate sampled data system with that of the continuous system to a step input, it is concluded that the response time of the output of the multirate sampled-data system is reduced by a multirate controller, the ripple between samples is lessened and all the transients are diminished within one period.

• 전기의세계
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• v.31 no.3
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• pp.226-234
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• 1982

DC choppers are usually used to control the DC motor by varying the average value of DC input voltage to the DC motors. In this paper, a chopper circuit is suggested and reconstructed by replacing the free-wheeling diode with the parallel capacitor in the conventional ones. It is demonstrated that this chopper circuit with capacitor can reduce the ripples of the output voltage and current in contrast to those of the chopper with diode, and it can be controlled the output waveforms smoothly at high power demand.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.7
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• pp.276-282
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• 1985

This study is concerned with the analysis of two-dimensional steady magnetic fields by the coupling of FEM and BEM. FEM(Finite Element Method)is most widely used as a method of numerical analysis and BEM (Boundary Element Method)is a newest method for it. And the results from this coupling method are compared and discussed with those of FEM only. Consequently, it is shown that to obtain the same accuracy of results the coupling method requires less calculating time and dimension than the FEM.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.7
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• pp.694-700
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• 1992

The digital computer control systems which are used in time sharing control or remote control may experience intermittent interruptions. Further it can be made unstable by the intermittent interruptions of a control computer. This paper presents a mathematical model with intermittent computer interruptions and an unstable output response through simulation. Also it presents to improve the control quality using extrapolation method in interrupt synchronizing feedback path.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.9
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• pp.521-527
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• 2003

This study presents the AC railway system modeled by EMTDC in detail. The ,model made by EMTDC have a lot of advantages. It could be available for the system change, simulated repeatedly and also applied regarding very complicated systems. EMTDC simulations to verify this model are compared with the hand calculations. It is confirmed that the model made by EMTDC is correctly designed.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.363-365
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• 2005

It describes a design analysis and test results of an energy transfer system which consists of two 0.5 MJ superconducting coil and three Inverter-Converter Bridges(hereinafter called ICB). A point of design is to satisfy the required stored energy capacity rather than magnetic field density with minimum energy transfer time using the calculation results of state-space averaging methods instead of Fourier series. It is proven that the considered methods are effectively through system experiments.

• 전기의세계
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• v.19 no.6
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• pp.1-7
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• 1970

In this paper, to determine process dynamic characteristics, the correlation method for measuring the impulse response of process using a pseudo-random binary signal as the test signal instead of white noise was studied. The error caused by using the signal of Mesquence signal generator which was built up by the authors was analysed. Experments were performed on the 1st and 2nd order lag systems and the results were in good coincidence with theoretical values. It is expected that applying these results, it may be possible to develop a continuous measuring method adaptable to modern control systems.