• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1694-1696
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• 2001

Partial discharge(PD) tests are used to evaluate the insulation condition of stator windings in six 6.6kV motors. These tests were conducted using a conventional partial discharge detector (PDD), turbine generator analyzer(TGA) and partial discharge analyzer(PDA). Off-line PD measurements were performed on six 6.6kV motors. PD magnitudes ranged from 740 pC to 5,100 pC at the normal line-to-ground voltage. Six 6.6kV motors have been equipped with eighteen 80pF epoxy-mica couplers(one per phase) on the motor terminal boxs. The PD pulse from sensors were measured with the TGA and PDA instruments on a normally operating motors. The PDD, TGA and PDA test results showed that internal discharge was detected in voids of the groundwall insulation.

• The Korean Journal of Ceramics
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• v.5 no.1
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• pp.19-24
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• 1999

The influences of TiB2 additions to the β-sialon on mechanical propeties and electrical discharge machinability were investigated. Samples were prepared by adding 15, 30 and 45 vol.% TiB2 particles as a second phase to a β-sialon matrix. The β-sialon-TiB2 composites were sintered by hot pressing in a nitrogen atmosphere at 1800℃ with pressure of 30 MPa. The fracture toughness of the composites was increased with TiB2 content except 45 vol.% TiB2 composite. The crack propagation and crack deflection were observed with a SEM for etched samples after vicker's indentation. The composites containing more than 30 vol.% TiB3 had resistivity lower than 10-3 Ω㎝. The electrical discharge machining (EDM) of composited was conducted with two kind of machines such as die-sinker and wire cutter. The machinability was evaluated with the cutting rate surface roughness after machining.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.178-184
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• 1996

Electrical properties such as surface flashover discharge and discharge degradations of insulating materials for superconducting cable have been investigated. It is found that the surface voltage is proportional to /$\^$0.7/(/: discharge length) in LHe(Liquid Helium). V-t characteristic LHe were a n=5.5 that was less than liquid N$_2$. After applied AC voltage, the surface condition of polymer films were observed non-eroded area and eroded area. The eroded area is depending on the applied voltage. In case of LHe, the crack was observed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.91-92
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• 2018

A glassy thin film was formed on the surface of the blast furnace slag. When blast furnace slag is used as an admixture of concrete, addition of alkali activators were required. However, alkali activators are not only dangerous as chemical products, but they are also difficult to use as expensive materials. Therefore, it is necessary to study the way of removal of the glassy thin film of blast furnace slag without the risk and cost increase. In this study, to solve this problem, experiment was carried out to improve the hydration reactivity by treatment the surface of blast furnace slag using arc discharge. Experimental results show that when the surface of the blast furnace slag was tratmented by arc discharge, the glassy thin film was destroyed. And the hydration reactivity was improved, the compressive strength was increased.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.101-102
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• 2000

The performance of ac plasma display panels (PDP) is influenced strongly by the surface glow discharge characteristics on the MgO thin films. This paper deals with the surface glow discharge characteristics and some physical properties of MgO thin films prepared by reactive RF planar unbalanced magnetron sputtering in connection with ac PDP. The samples prepared with the de bias voltage of -10V showed lower discharge voltage, lower erosion rate by ion bombardment, higher optic transparency and higher crack resistance in annealing process than those samples prepared by conventional magnetron sputtering or E-beam evaporation.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.9
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• pp.883-892
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• 1991

This paper presnets the characteristics of electropolymerization and electrochemicla propoerties of polyaniline(PAn). From the morphology study on the PAn surface, it seems that coagulation of the fibrils on the surface proceeds as the PAn grows, resulting in fibril clusters with new branches and more extensive voids. While PAn/Li cell is cycled at potential range between 2.9V and 3.7V in which the first strong reduction peak of 2.75V does not appear, its oxidation reduction capacities were increased up to about tenth cycle. Electricity efficiency of stable charge-discharge to deep discharge in PAn/Li cell was 42.9%. Average charge potential, avergae discharge potential, energy density, and charge-discharge energy efficiency of the PAn/Li cell were 3.4V, 3.25V, 132.9Wh/kg, and 95.6%, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.8
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• pp.622-628
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• 2001

We developed 1- and 2-dimensional fluid model for the analysis of a capacitively coupled Ar RF(Radio Frequency) glow discharge. This discharge is in pure Ar gas at the pressure 100[mTorr], frequency 13.56[MHz] and voltage amplitude 120[V}. This model is based on the equations of continuity and electron energy conservation coupled with Poison equation. 2-dimensional model is simulated on the condition of GEC(Gaseous Electronic Conference cell). The geometry of the discharge chamber and the electrodes used in the model is cylindrically simmetric; tow cylinders for the electrodes are surrounded by the grounded chamber. It is shown that 1-dimensional model is very useful on the understanding of RF glow discharge property and of the movement of charged particles. 2-dimensional model predicts off-axis maximum structure as in the experiments and has the results in qualitatively and quantitatively good agreement with the experiments. Effects of dc self-bias voltage, guard ring and reactor geometry is discussed.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1346-1353
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• 2009

In this study, a numerical study was carried out to simulate the expansion of ground borehole by pulse discharge technology using finite element analysis. Considering the mortar in the borehole as an acoustic medium and the surrounding soil as an elasto-plastic material, the strong shock wave developed by the pulse discharge was modeled using the underwater explosion model. The ground expansion was simulated based on a coupled acoustic-structural analysis with varying properties of mortar and soil, and the behavior between acoustic-structural interface.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.50 no.3
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• pp.125-129
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• 2001

ln this paper, a ozone generator using superimposition of silent discharge has been designed and manufactured. This type ozone generator is equipped with three electrodes and two gaps. Ozone is generated by superimposition of silent discharge, which is respectively come from two gaps. The maximum values of ozone concentration, ozone generation flow and ozone energy field were obtained 4,750[ppm], 2.37[g/h], 102.3[g/kWh]. Also, the result of reaction of 1,8921ppm] ozone and the sampling water from the lake, the water quality was improved from IV grade to In grade, and obtained 100[%] sterilization rate of Escherichia coli within 5.0(min).

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1930-1932
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• 2000

PD in defects of solid insulation system is very harmful since it leads to deteriorate insulation system by. the discharge electrons and ions bombarding the insulation surface and the action of chemical products that are formed by discharges. PD is used to detect and recognize defects and degradation of insulation system However, there are still marked difficulties to recognize defects by PD methode. In this paper, we investigated properties of PD of defects in solid insulation by using statical methods and classified PD patterns of surface discharge, electrical tree and void discharge with source of discharge, we used specific distributions such as $H_n(q)$, $H_{an}(\phi)$, $H_n(\phi)$, $H_a(\phi)$ to recognize defects of solid insulation system.