• KEPCO Journal on Electric Power and Energy
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• 제1권1호
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• pp.145-150
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• 2015

This paper described the medium voltage high temperature superconducting cable thermal simulation and its application. New simulation method for HTS cable modeling using PSCAD/EMTDC is introduced in this paper. The developed simulation method consists of electrical model part and thermal model part. In electrical model part, power loss and thermal capacitance can be calculated in each layer, then the temperature of each layer can be calculated by power loss and thermal capacitance in thermal model part. This paper also analyzes the electrical and thermal characteristic in the case of normal operating condition and transient including single line to ground fault and line to line ground fault using new simulation method.

• 설비공학논문집
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• 제9권1호
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• pp.1-13
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• 1997

This paper reports the dynamic analysis of energy consumption for an office building by heat resistance-capacitance method. If a building is divided into several wall components and the wall components is replaced by one thermal capacitance and several thermal resistances, the building becomes an electric circuit. By solving the simultaneous equations of the circuit, the dynamic heat transfer characteristics and the energy consumption rate of the building were predicted. Accuracy of modified BIN method was evaluated by the present resistance-capacitance method. The result shows that modified BIN method overpredicts the heating load of the office building 15%. Annual energy consumptions of equipments(fan, boiler, chiller) for various ventilating control system(CAV, VAV, FCU+VAV, FCU+CAV) were compared. FCU+CAV shows the minimum annual energy consumption.

• 조명전기설비학회논문지
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• 제24권12호
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• pp.171-176
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• 2010

This paper presents the electric field for 22.9[kV]/380[V], 2[MVA] mold transformer are analysed using FEM(finite element method). The electric field was calculated for the voltage applied to the transformer. Then, it is analysed that the maximum electric field occurred between high voltage turns. Capacitance is calculated with energy method. Surge impulse test simulation is studied by modeling circuit with capacitance and inductance. This paper obtain the result that is about influence of electric field in distribution mold transformer adopted.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2010-2012
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• 2005

Activated carbon was activated with chemical treatment to attain high surface area with porous structure. We have been considered activated carbon is the ideal material for high voltage electric double layer capacitor due to their high specific surface area, good conductivity and chemical stability. In this study we found that increase in electrochemical capacitance due to activated carbon. Also chemically activated carbon and water treatment have resulted larger capacitance and also exhibits better electrochemical behavior, and is about 15% more than in untreated state. The structural change in activated carbon through chemical treatment activation was investigated by using SEM and XRD. In this study, the dependence of the activation behavior with KOH in the micro structure of host materials will be discussed. Furthermore, the relation to the electric double layer capacitance, especially the specific capacitance per unit area, is also discussed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.399-402
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• 1999

In this paper, a new method for calculating capacitance in arbitrarily shape structure is Presented. This new approach based on divergence theorem of Gauss\`s law is acheive by Surface-Contacted Element(SCE) for Gaussian surface. To evaluate accurate capacitance value in nonuniform electric field. in two dimensional analysis the interpolation using the elements which contact one nod (PE: Point-Element) or two nod (FE: Face-Element) is employed. Because the elements contacted with surface are very small compared with total elements in analytic model, SCE method has shorter computing time to calculate capacitance. This proposed method is verified by comparing the simulated results with value obtained by analytic method.

• 대한기계학회논문집B
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• 제37권8호
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• pp.775-780
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• 2013

일반적으로 전기자동차(Electric Vehicle, EV)의 배터리로는 리튬-이온 전지가 많이 사용된다. 리튬-이온 전지는 충전이 가능한 이차 전지의 일종으로 마이크로 스케일의 극판과 분리막이 반복하여 적층된 구조를 가지고 있다. 이와 같은 미세구조로 인해 상세해석모형을 적용하는 것은 지나치게 많은 비용이 소모되는 일이다. 본 연구에서는 리튬-이온 전지를 하나의 등가물성으로 나타내는 방법을 제시하고 있으며, 185.3Ah 전지와 20Ah 전지에 이를 적용하여 그 결과를 이전자료와 비교하고 있다. 또한 집중용량법을 적용한 계산 결과를 함께 제시하여 유한요소법(FEM)이나 유한체적법(FVM)의 사용 없이 손쉽게 전지의 열적 거동을 확인할 수 있는 방법을 제시하였다.

• 전기화학회지
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• 제6권4호
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• pp.255-260
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• 2003

다공성 탄소전극의 전위에 짜른 EDLC(e)ectric double-layer capacitor)특성을 조사하기 위해 복소캐패시턴스분석(complex capacitance analysis)을 수행하였다. 하나의 원통형 기공에 대해 복소캐패시턴스를 이론적으로 유도하였고, 기공의 분포를 고려하여 다공성 전극에 대하여서도 계산하였다. 복소캐패시턴스의 허수부를 주파수에 대해 도시하면 피크 형태의 곡선이 얻어지는데, 이때 피크의 면적은 캐패시턴스 값의 크기와, 피크의 위치는 다공성전극의 전기화학 파라매터와 기공구조에 의해 결정되는 $\alpha_0$와 상관관계가 있음을 알 수 있었다. 이를 이용하면, 동일한 기공구조를 갖는 전극에 대해, 전위에 따른 캐패시턴스와 기공 내 이온전도도의 변화를 측정할 수 있다. 메조포러스 탄소전극에 대하여 전위를 변화시키며 electrochemical impedance spectroscopy를 측정하고 이를 복소캐패시턴스법에 의해 분석하였다. 피크 면적으로부터 구한 전위에 따른 캐패시턴스는 0.3V부근에서 최대값을 가졌는데, 이는 cyclic voltammetry 실험결과와도 일치하였다. 한편, 피크 위치로부터 구한 기공 내 이온전도도는 0.2V에서 최대 값을 가지고 전위가 증가할 수록 서서히 감소하였다. 이를 탄소 표면전하의 증가로 인해 이온/표면의 전기적 작용력이 커졌기 때문으로 해석하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.979-982
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• 1999

A new accurate as well as efficient multi-layer interconnect capacitance extraction method is presented. Since Multi-layer interconnects is too complicated to directly extract capacitances, it is simplified with virtual ground concept. To make the structure tractable, the shielding effects should be separately determined. Since the electric field shielding effects, and the solid-ground-based capacitance matrices can be readily determined from the layout geometry, the accurate as well as efficient quasi-3D capacitances concerned with an objective line can be readily determined. In order to demonstrate its efficiency and accuracy, the parameters and circuit responses were benchmarked with 3D-field-solver-based results.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.256-256
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• 2013

Carbon nanotubes (CNT) / polyvinylidene fluoride (PVDF) piezoelectric composite films for nanogenerator devices were fabricated by spray coating method. When the CNT/PVDF mixture solution passes through the spray nozzle with small diameter by the compressed nitrogen gas, electric charges are generated in the liquid by a triboelectric effect. Then randomly distributed ${\beta}$ phase PVDF film could be re-oriented by the electric field resulting from the accumulated electrical charges, and might be resulted in extremely one-directionally aligned ${\beta}$ phase PVDF film without additional electric field for poling. X-ray diffraction patterns were used to investigate crystal structure of the CNT/PVDF composite films. It was confirmed that they revealed extremely large portion of the ${\beta}$ phase PVDF crystalline in the film. Therefore we could obtain the poled CNT/PVDF piezoelectric composite films by the spray coating method without additional poling process. Charge accumulation and resulting electric field generation mechanism by spray coating method were shown in Fig. 1. The capacitance of the CNT/PVDF films increased by adding CNTs into the PVDF matrix, and finally saturated. However, the I-V curves didn't show any saturation effect in the CNT concentration range of 0~4 wt%. Therefore we can control the performance of the devices fabricated from the CNT/PVDF composite film by adjusting the current level resulted from the CNT concentration with the uniform capacitance value.

• Carbon letters
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• 제16권2호
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• pp.78-85
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• 2015

Activated carbons (ACs) were prepared by activation of coal tar pitch (CTP) in the range of $700^{\circ}C-1000^{\circ}C$ for 1-4 h using potassium hydroxide (KOH) powder as the activation agent. The optimal activation conditions were determined to be a CTP/KOH ratio of 1:4, activation temperature of $900^{\circ}C$, and activation time of 3 h. The obtained ACs showed increased pore size distribution in the range of 1 to 2 nm and the highest specific capacitance of 122 F/g in a two-electrode system with an organic electrolyte, as measured by a charge-discharge method in the voltage range of 0-2.7 V. In order to improve the performance of the electric double-layer capacitor electrode, various mixtures of CTP and petroleum pitch (PP) were activated at the optimal activation conditions previously determined for CTP. Although the specific capacitance of AC electrodes prepared from CTP only and the mixtures of CTP and PP was not significantly different at a current density of 1 A/g, the AC electrodes from CTP and PP mixtures showed outstanding specific capacitance at higher current rates. In particular, CTP-PP61 (6:1 mixture) had the highest specific capacitance of 132 F/g, and the specific capacitance remained above 90% at a high current density of 3 A/g. It was found that the high specific capacitance could be attributed to the increased micro-pore volume of ACs with pore sizes from 1 to 2 nm, and the high power density could be attributed to the increased meso-pore volume.