• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.7
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• pp.310-313
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• 2003

The purpose of this paper is to evaluate the effects of pre-formed space charges by DC stress on partial discharge(PD) characteristics in XLPE. We have suggested a modified pulsed electro-acoustic(PEA) method and successfully measured both space charge distribution and current simultaneously. It has been demonstrated that the PD patterns are strongly influenced by the pre-formed space charge distributions, which are hardly disappeared up to AC 8㎸ in electrode configuration including air gap between XLPE layer and electrode. From the results, it could be said that the pre-formed space charges by DC stress can play harmful and dangerous roles in insulating system under AC operating voltages because of the field distortion and localization due to the pre-formed space charge.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.12 no.1
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• pp.94-102
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• 1999

Ni/CGO cermets were fabricated as the anode for SOFC which uses CGO as the electrolyte. And their electrical conductivity, electrochemical reactivity, and thermal expansion coefficient were optimized through the variation of NiO/CGO particle size ration and their composition. The electrical conductivity of the cermet was increased abruptly at a certain Ni content and the percolation concentration was decreased with the decreasing particle size ratio. Anodic overpotential was also decreased with the decreasing particle size ratio. For a fixed ratio it showed a minimum value at 50 wt.%. Thermal expansion coefficient was increased monotonically with increasing Ni contents, however it did not depend on the size ratio. With three properties taken into account, the cermet of particle size ration of 0.03 and composition of 50 wt.% was judged to be optimal as the anode.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.5
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• pp.206-212
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• 2003

It is hard to expect excellent electrical, mechanical and chemical properties from most of the composite materials presently used as insulators due to insufficient wettability property caused by the difference of interfacial properties between the matrix material and the reinforcer. Therefore, various interfacial coupling agents have been developed to improve the interfacial properties of composite materials. But if the wettable coupling agents are used outdoor for a long time, change in quality takes place in the coupling agents themselves, bringing about deterioration of the properties of the composite materials. In this study, glass surface was treated by plasma to examine the effect of dry interface treatment without coupling agent. It was identified that the optimum parameters for the best wettability of the samples at the time of generation of plasma were oxygen atmosphere, 0.1 torr of system pressure, 100 W of discharge power, and 3 minutes of discharge time. Also, the surface resistance rate and dielectric property were improved.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.1995-1999
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• 2009

A partial discharge(PD) measurement is a very effective method to assess the insulation condition of high-voltage machines. It is necessary that the life time of the on-line PD measurement sensor is assessed. Therefore, the electrical life time assessment method of ceramic element was reviewed in order to estimate the life time of the on-line PD measurement sensor. The samples were prepared according to the reviewed method and were tested at 8kV, 9kV and 10kV. Based on the obtained results, the life time constant is shown above 59. Also, it is assumed that the estimated life time constant can be used to anticipate the life time and to assess the conformity of the on-line PD measurement sensor.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.1
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• pp.70-75
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• 2013

The electrical separation joint as a filter circuit distributes the track circuit frequency. The electrical separation joint is classified into the interval where reinforcing bars are insulated and not insulated through the length of track circuit. In case of incorrectly setting up the length of electrical separation joint, the amplitude of current on the track circuit is not over standard current which is the standard of current on the track circuit and it effects on the close frequency on track circuit. Then, it makes an accident or makes a train not receive information for train control. In this paper, the electrical separation joint model is suggested and parameters are numerically calculated in the model. Moreover, the length of electrical separation joint is analyzed and is demonstrated by uisng Matlab and PSpice program.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.2
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• pp.102-109
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• 1997

The width of fuzzy membership function and control rule has an effect on performance of the fuzzy controller for electric equipment systems. In this paper, the neuro-fuzzy controller is proposed to im¬prove the performance of fuzzy controller. It has the width of membership function, that is adapted to the electrical parameter using multi-layer neural network, it is applied to first order electric power system with dead time and various plant constant. The related simulation resolts show that the pro¬posed neuro fuzzy controller are superior characteristics of improved performance

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.8 no.1
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• pp.57-62
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• 1994

In this paper, a system for measuring of treeing degradation in organic dielectric material by using image processing technics, is discussed. Traditionally, treeing is measured by visual method. It made difficulty to understanding for features and changes in the configlEation of the tree growth. Using image processing system, it is made to describe the characters of the tree growth, specially length of tree and area of treeing degradation. From this image processing and visual measurement, the similar results were made, an automatic measurement system was made for configuration of the tree growth.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.429-433
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• 2004

Most utiltity systems are subject to frequent changes, often due to increased loads and demand to up-grade quality of service provided. Urban renewal, expressway construction and suburban growth have also caused significant changes in urban utility distribution systems. Recently, it is required that a guideline for planning of a complete system, the reasonable design and construction methods for the efficient installation common utility tunnels must be estabilished. It prompts drastic measures to guard cities and their inhabitants against the horror of massive fires in the future. Preparedness holds the key to safety.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.10
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• pp.126-133
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• 2008

Computer and communication of based IT technology use to das that remote control, monitoring, measuring automatic gas switch, recloser located far about $20{\sim}30[km]$. For increasing efficiency billing, metering of high voltage customer use to amr system. If between das and amr interface operate when generated fault in high voltage electric equipment of customer part, amr system serve to das quickly in fault information data, correct fault location.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.12
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• pp.1211-1217
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• 1991

A three dimensional magnetostatic probodm is analyzed using the boundary element method and the magnetic scalar potential are employed in order to reduce the size of system matrix. Although the total magnetic scalar potential gives very accurate solutions at inner and outer regions of magnetic materal, the method has limitation on application because the magnetic scalar potential due to applied magnetic field sources is hard to be obtained. The reduced magnetic scalar potential gives more or less inaccurate solutions inside the magnetic material but very accurate solutions outside. Hence it can be concluded that the reduced magnetic scalar potential is very useful when the magnetic fields of outside of magnetic fields of outside of magnetic material are interested. It is also shown, from the numerical example, that the linear shape function gives more efficient solutions than the constant shape functions.