• 조명전기설비학회논문지
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• 제26권4호
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• pp.82-87
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• 2012

In this paper, flashover characteristics of air in the vertical arrangement of cylinder-shaped rod and plane gap in the case of combustion flame on the plane electrode were examined under the application of a.c. and d.c. high-voltages. In order to investigate the effect of propane flame on the flashover characteristics of air, flashover voltages in accordance with the variation of the gap length and the horizontal distance between the flame and the high-voltage rod electrode were measured. As the result of the experiment, flashover voltages in the presence of the flame were substantially lowered than those in the absence of flame, and the polarity effects with the d.c. voltages on appeared owing to the flame. Flashover voltages of air were increased in the proportion of the gap length and the horizontal distance in the case of both a.c. and d.c. voltages, but the flame was extinguished by such corona wind that was produced from the rod electrode when the gap length and the horizontal distance reached to a certain degree.

• 조명전기설비학회논문지
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• 제27권8호
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• pp.83-89
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• 2013

In this paper, discharge characteristics of air in the vertical arrangement of three rods(dome-shaped, cylinder-shaped, and needle-shaped rod) and plane gap having propane flame on the plane electrode are examined under the application of a.c. and d.c. high-voltages. As the result of the experiment, flashover voltages in the presence of the flame are substantially lowered than those in the absence of flame, and relative a.c. flashover voltages in the dome-shaped, cylinder-shaped, and needle-shaped rod gaps are found 32.5%, 32.1%, and 26.4% respectively. The polarity effects with the d.c. voltages are shown, and flashover voltages in negative polarity are much lowered than those in positive one. The negative flashover voltages in the dome-shaped and cylinder-shaped gaps are found 18.3% and 18.7% respectively, but the positive ones are found 53.5% and 43.2% respectively. In the needle-shaped rod gaps, meanwhile, the flame is extinguished by corona wind, and the quenching voltages are found 28.4% under the application of a.c. voltages. The ion winds of corona and the reduction of air density are the main factors of flashover reduction owing to the flame in the case of a.c. voltages, but the electrifications of the positive ion by thermal ionization besides the above factors are remarkably found in the case of d.c. voltages.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기물성,응용부문
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• pp.208-212
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• 2001

In this paper, characteristics of the ac and do flashover voltages in the vertical air gap of a needle-plane, sphere-plane and rod-plane electrode system were investigated when the combustion flames were present near the high-voltage electrode. As the results of an experimental we found that the reduction of flashover voltages characteristics with the vertical distance caused, in comparison with the no-flame case were about 1/3 times when a short sap d=1[cm] and 2[cm] of the ac voltages were applied. Also, flashover voltages characteristics of the do negative polarity under sphere-plane and rod-plane electrode system with the combustion flame were increased about two times than those of the do positive polarity.

• 대한전기학회논문지
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• 제39권9호
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• pp.964-975
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• 1990

This paper aims at the design of high voltage electrode contour under specified field condition. Defining the contour with B-Spline curve, the number of contour variables can be reduced and very smooth electrode can be obtained. For the analysis of the electric field, Surface Charge Method which has advantages in practical model has been used. As an initial contour, the rod-plane gap has been used since the difference between maximum and minimum field value is relatively large. Various field conditions including uniform field condition are given to the end of the rod electrode. Under uniform field condition, authors designed an electrode whose field-deviation was under 0.5%. Finally, the relation between the curvature and field of the electrode has been checked, which showed that B-Spline curve is appropriate for the shape function.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1181-1187
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• 2015

Sulfur hexafluoride (SF₆) gas is used widely in electric power equipment such as Gas Insulated Switchgear (GIS), Gas Insulation transmission Line (GIL), and Gas Circuit Breaker (GCB). But applications of SF₆ should be restricted because SF6 gas is one of the greenhouse effect gases. To reduce use of SF₆ gas, a study on eco-friendly alternative insulation medium is needed. In this paper, we investigated lightning impulse (LI) breakdown of dry-air which is attracting attention as an ecofriendly alternative gas and the LI breakdown of hybrid insulation combined with dry-air and solid insulation (Room-Temperature Vulcanizing Silicone Rubber-RTV SIR) and dry-air in inhomogeneous fields according to gap distance and pressure. The experiment results showed that the LI breakdown strength of hybrid insulation system was higher than that of dry-air insulation system. It was verified that the development of technology related to eco-friendly power apparatus compact such GIS, GCB and GIL can be used as basic research data.

• 한국전기전자재료학회논문지
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• 제11권4호
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• pp.321-326
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• 1998

Electrical breakdown characteristics of liquid nitrogen($LN_2$) taking into consideration for application of high $T_c$ superconductor is very important. Also $LN_2$ will be used as both coolant and insulator in superconducting generator. In this paper, we investigated ac breakdown characteristics of cryogenic nitrogen gas above a $LN_2$ for rod-to plane electrode configuration. As result the breakdown mechanism of $LN_2$is dependence on bubble effect. And breakdown voltage is a ratio on bubble s size but electrodes arrangement is to make no difference. The breakdown voltage decreases slightly with increasing flow velocity, it again decreases abruptly with increasing flow velocity. These results were interpreted as the within pressure of rod electrode and Maxwell force.

• Transactions on Electrical and Electronic Materials
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• 제14권6호
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• pp.317-320
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• 2013

Partial discharge resistance for the epoxy systems with two diluents was investigated in the rod-plane electrodes arrangement, and the effect of electric frequency on the partial discharge resistance was also studied. Diglycidyl ether of bisphenol A (DGEBA) type epoxy was used as a base resin, and 1,4-butanediol diglycidyl ether (BDGE) or polyglycol (PG) as a reactive diluent was introduced to the DGEBA system, in order to decrease the viscosity of the DGEBA epoxy system. BDGE was acted as a chain extender, and PG acted as a flexibilizer, after the curing reaction. To measure the partial discharge resistance, 5 kV alternating current (ac) with three different frequencies (60, 500 and 1,000 Hz) was applied to the specimen in a rod-plane electrode arrangement, at $30^{\circ}C$. PG had a good effect, while BDGE had a bad effect on the partial discharge resistance of the DGEBA system, regardless of the electric frequency.

• 한국화재소방학회논문지
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• 제16권1호
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• pp.30-38
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• 2002

가공 전력선로 아래에서 화재가 발생되면 전력선은 예기치 않은 섬락사고가 세계 여러나라에서 관측되고 있다. 본 연구에서는 화재의 발생으로 연소화염이 존재할 때, 주변 공기의 절연내력에 미치는 화염의 영향을 알아보기 위해 모의된 조건에서 여러 가지 실험을 행하였다. 침대평판, 구대평판 및 봉대평판 전극을 수직배치한 경우, 교류 및 직류 섬락전압 특성을 조사하였다. 실험결과, 구대평판 갭의 경우, d=1 cm 및 2cm일 때 교류섬락 전압의 상대값은 23.5% 및 30.4%이며, d=4cm인 경우는 37.8%인 것으로 나타났으며, 화염이 없는 경우에 비해 평균 33.0%인 것으로 나타났다. 직류전압 인가시는 화염이 없는 경우, 부극성의 섬락전압이 정극성보다 높았으나, 화염이 존재할 경우는 반대로 정극성이 부극성 전압보다 높은 것으로 나타났다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권3호
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• pp.200-208
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• 1999

In this paper, the corona discharge is analyzed by Finite Element Method(FEM) combined with Flux-corrected Transport(FCT) algorithm. In the previous papers, Finite Difference Method(FDM) combined with FCT was used. Usually in the FDM, the regionof interest is discretized with structured grids. But to refine local regions with same resolution, much more grids are required for the structured grids than for unstructured grids than for unstructured grids. Therefore, we propose the FEM-FCT method to simulate the corona discharge. The proposed method has good flexibility in model shape and can reduce the computational cost by the local refinement where the physical quantities have steep gradients. Using the proposed method, we study the streamer growth of parallel plate electrodes which is initiated by the low and high perturbation density. We find that the varying the initial density of perturbation has very little effect on the streamer propagation. And the corona discharge of the rod-to-plane electrode is simulated. On the surface of the rod electrode, the high concentration of the electric field gives rise to many number of streamer seeds. The strong axial streamer propagate to the plane electrode. The weaker non-axial streamer repel each other and stop growing more. The results are very similar to those of the papers which used the FDM-FCT method on structured grids. Thus we can conclude that the proposed FEM-FCT method is more efficient than the conventional FDM-FCT method by virtue of the reduction in computational grids number.

• Korean Chemical Engineering Research
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• 제50권1호
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• pp.162-166
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• 2012

본 연구에서는 전해증착법과 열처리를 통하여 ITO 투명전극 위에 고밀도의 ZnO 막대구조를 형성하는 방법을 조사하였다. 증착과정에서 $Zn(OH)_2$와 ZnO가 함께 형성되는 것을 고려할 때 전기화학적 ZnO 증착효율은 33% 이하를 나타내었다. $500^{\circ}C$ 열처리 후 ZnO는 (002)를 선택적으로 갖는 결정구조를 형성하며, 나노막대 구조의 성장속도는 0.986 ${\mu}m/hr$로 측정되었다. 그리고 전기화학적으로 제조한 ZnO 막대를 염료감응 태양전지의 전극으로 사용시 측정된 전지효율은 0.21%로서 태양전지용 전극으로서의 가능성을 확인하였다.