• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권9호
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• pp.448-453
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• 2003

In this paper the controlled closing algorithm of the circuit breaker for isolated capacitor banks is proposed. The characteristics of circuit breakers such as RDDS(rate of decrease of dielectric strength) and a mechanical operating tolerance should be also taken into account to locate contact touch instants around voltage zero. The analysis results on the voltages across circuit breaker terminals upon closing operation play an important roles to describe the suggested method. The simulations carried out in order to verify the performance of this method show that the closing instants obtained from the proposed method provide a good suppression effect on the closing transients for both single and back-to-back capacitor banks.

• 전기학회논문지
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• 제61권4호
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• pp.601-605
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• 2012

The non-controlled closing of High-voltage SF6 gas circuit breaker can cause transient current and overvoltage in the field. The controlled closing technology is an effective way to reduce transient current and voltage, prevent equipment failures, and improve power quality. For the development of controlled closing, it is obviously necessary to determine the withstand voltage between arc contacts of High-voltage SF6 gas circuit breaker in making operation. This paper focuses on decrease of pressure and density of SF6 gas that can affect withstand voltage between arc contacts in making operation. The dielectric strength between arc contacts could be improved by minimizing the decrement of pressure and density of SF6 gas obtained by simulation and test and moreover the rate of decrease of dielectric strength (RDDS) of arc contacts could be foreseen.

• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3539-3543
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• 2012

Butacaine sulfate is an ester of p-aminobenzoic acid which has been widely used as a local anaesthetic and it is a long standing agent particularly for spinal anaesthesia. For this reason, a kinetic study of oxidation of butacaine sulfate by sodium N-chlorobenzenesulfonamide (chloramine-B or CAB) has been carried out in $HClO_4$ medium at 303 K in order to explore this redox system mechanistic chemistry. The rate shows a first-order dependence on both $[CAB]_o$, and $[substrate]_o$, and a fractional-order dependence on acid concentration. Decrease of dielectric constant of the medium, by adding methanol, increases the rate of the reaction. Variation of ionic strength and addition of benzenesulfonamide or NaCl have no significant effect on the rate. The reaction was studied at different temperatures and the activation parameters have been evaluated. The stoichiometry of the reaction has been found to be 1:2 and the oxidation products have been identified by spectral analysis. The observed results have been explained by plausible mechanism and the related rate law has been deduced.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권12호
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• pp.664-669
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• 2002

In this paper the method to determine tire optimal switching instants in order to reduce the transient surges during switching not relevant to the neutral treatment of shunt reactors is presented. This method consists of the following two steps. First, the instants of the voltage peaks between the contacts of each poles and the voltage magnitude as well as the moments of the current zero crosses were found out analytically. Next, the instants of the contact touches or separations were determined in consideration of the rate of decrease of dielectric strength or a circuit breaker and the variation of the its operating time. The results obtained from the EMTP(Electromagnetic Transient Program) analysis studies show that the making instants are established at the peak voltage of each three poles for any conditions of a neutral point and the possible upper limited values of inrush currents due to the variation of the mechanical operating time can be estimated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.774-776
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• 2003

In this paper the controlled closing algorithm to locate contact touch instants within the span in which the making voltage is minimized is proposed with the characteristics of circuit breakers such as RDDS(rate of decrease of dielectric strength) and a mechanical operating tolerance taken into account. The analytic results on the voltages across circuit breaker terminals upon closing operation play an important roles as references to describe the suggested method. Even though in the case of the isolated neutral capacitor banks, it is possible to decide the optimum contact instants without any dedicated procedures.

• 수산해양기술연구
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• 제21권1호
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• pp.75-81
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• 1985

직교이방향 이층 유리섬유 강화 Epoxy 수지를 사용하여 인장축에 대해 섬유방향이 0$^{\circ}$, 15$^{\circ}$, 25$^{\circ}$ 및 45$^{\circ}$인 시료로 인장시험 및 전기절연 강도시험을 통하여 얻은 결과는 다음과 같다. 1) 섬유방향이 인장축에 대해 0$^{\circ}$에서 45$^{\circ}$로 증가함에 따라 항복응력 및 파단응력은 감소하는 경향이고 특히 0$^{\circ}$와 15$^{\circ}$ 사이에서 급격한 변화율을 보인다. 2) 파단시 변화율은 인장방향에 대한 섬유방향이 45$^{\circ}$인 경우 최대치를 나타냈고 15$^{\circ}$~45$^{\circ}$ 범위에서 급격한 변화율을 보인다. 3)섬유의 방향이 동일할 경우 인장력을 많이 받은 시료일수록 최대절연강도 값은 낮아졌고 인장방향과 섬유방향의 교각이 증가할수록 최대절연강도 값을 나타내는 압축응력의 값은 낮은 점으로 이동하는 경향을 보였다. 4) 기계적 특성과 같이 섬유방향이 45$^{\circ}$인 경우의 시료가 가장 나쁜 전기적 절연강도 특성을 나타냈다.

• Carbon letters
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• 제25권
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• pp.1-13
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• 2018

Gold functionalized graphene oxide (GOAu) nanoparticles were reinforced in acrylonitrile-butadiene rubbers (NBR) via solution and melt mixing methods. The synthesized NBR-GOAu nanocomposites have shown significant improvements in their rate of curing, mechanical strength, thermal stability and electrical properties. The homogeneous dispersion of GOAu nanoparticles in NBR has been considered responsible for the enhanced thermal conductivity, thermal stability, and mechanical properties of NBR nanocomposites. In addition, the NBR-GOAu nanocomposites were able to show a decreasing trend in their dielectric constant (${\varepsilon}^{\prime}$) and electrical resistance on straining within a range of 10-70%. The decreasing trend in ${\varepsilon}^{\prime}$ is attributed to the decrease in electrode and interfacial polarization on straining the nanocomposites. The decreasing trend in electrical resistance in the nanocomposites is likely due to the attachment of Au nanoparticles to the surface of GO sheets which act as electrical interconnects. The Au nanoparticles have been proposed to function as ball rollers in-between GO nanosheets to improve their sliding on each other and to improve contacts with neighboring GO nanosheets, especially on straining the nanocomposites. The NBR-GOAu nanocomposites have exhibited piezoelectric gauge factor (${GF_{\varepsilon}}^{\prime}$) of ~0.5, and piezo-resistive gauge factor ($GF_R$) of ~0.9 which clearly indicated that GOAu reinforced NBR nanocomposites are potentially useful in fabrication of structural, high temperature responsive, and stretchable strain-sensitive sensors.