등가반경개념에 의한 코어링 접지공사의 고찰

김세호,김일환,양문길 한국조명전기설비학회 2003 조명·전기설비학회논문지 Vol.17 No.5

대지 저항률이 높은 암반, 사력층 지역에서의 접지 저항은 일반적인 봉형 접지 전극으로는 얻기가 거의 불가능 하며 원하는 저항값을 얻기 위해서는 깊이 매설한 접지 전극과 접지 저항 저감제를 충분하게 사용하는 코어링 접지 방식을 채택하여 시설하는 것이 적절하다고 판단된다. 본 연구는 둥가반경 개념을 이용하여 코어링 접지 전극의 반 경이 확장되는 것을 보였으며 이릎 토대로 낮은 접지 저항이 얻어지고, 제주지역과 같이 고저항 지대에서의 각 토 양의 대지 저항률을 추정함으로써 다른 고저항 지대에서의 접지공사시 개략적인 접지저항을 예측하여 기초 자료로 사용할 수 있도록 하였다. The grounding system is necessary to provide means to dissipate electric currents into the earth without exceeding any operating and equipment limits. The ground is composed of various soils and the resistivity of the soil depends on many parameters. It depends on the type of soil and varies with distance as well as with depth. Especially, soil resistivity of volcanic area such as Jeju is ve교 high and it is difficult to acquire necessary grounding resistivity. This paper introduces the efficient grounding construction using coring technique for proper grounding resistance in high resistivity area. Because it is difficult to measure the accurate resistivity of soils, their resistivities are estimated using measured value of ground resistance and equivalent radius method. Estimated resistivities are used for grounding resistance in scheduled construction region.

고저항 지대에서의 코어링 접지공사에 관한 연구

김세호,김일환,양문길 제주대학교 공과대학 첨단기술연구소 2002 尖端技術硏究所論文集 Vol.13 No.2

The resistivity of the soil depends on many parameters. It depends on the type of soil and therefore varies with distance as well as with depth. Especially soil resistivity of volcanic area is very high and it is difficult to acquire necessary grounding resistivity. This paper introduces the efficient grounding construction using coring technique for proper grounding resistance in high resistivity area. Because it is difficult to measure the accurate resistivity of soils, their resistivities are estimated using measured value of ground resistance and equivalent radius calculation method. Estimated resistivities are used for grounding resistance in scheduled grounding region.

반구형 전극계에서 물의 저항률을 이용한 접지시스템의 등가회로 구성

이복희(Bok-Hee Lee),최종혁(Jong-Hyuk Choi),배성배(Sung-Bae Bae) 한국조명·전기설비학회 2008 조명·전기설비학회논문지 Vol.22 No.8

현재 우리나라의 접지시스템의 설계기준은 낮은 주파수에서 측정된 저항값을 기반으로 한다. 고주파 성분을 포함하는 뇌서지가 접지시스템에 인가되면 접지임피던스는 정상상태의 저항과 매우 다르게 된다. 이 논문은 접지시스템의 고주파 성능에 대한 물의 저항률의 영향을 파악하기 위하여 대지를 모의하는 수조를 이용하여 물의 저항률에 따른 어드미턴스의 주파수 의존성을 기술하였다. 500[Ωㆍm] 이상의 높은 물의 저항률에서 용량성 효과에 의해 주파수가 증가함에 따라 어드미턴스와 컨덕턴스가 증가하는 것으로 나타났다. 반면에, 500[Ωㆍm] 미만의 낮은 저항률에서는 유도성 효과에 의해 주파수가 증가함에 따라 어드미턴스와 컨덕턴스가 감소하는 것으로 나타났다. 또한 200[㎑]에서 5[㎒]에 이르는 주파수 범위에서 전류와 전압의 위상차가 증가하는 것으로 나타났다. 결론적으로, 접지시스템의 주파수 의존성은 대지의 저항률과 밀접한 관계가 있으며, 주파수와 대지저항률이 접지시스템의 성능에 미치는 영향에 대한 고려가 필요하다. A design criterion of grounding systems is commonly based on the ground resistance measured with low frequency in Korea. When lightning grus which have high frequency components are injected into the grounding system, the grounding impedance is greatly different morf the static grounding resistance. In order to investigate the effect of water resistivity on the high frequency performance of grounding systems, this paper presents the frequency-dependent admittance using water tank simulating the grounding system in different water resistivities. As a result, because of capacitive effect admittances and conductance are increased with increasing frequency in higher water resistivity of greater than 500[Ωㆍm]. On the other hand, admittances and conductances are decreased with increasing frequency due to inductive effect in lower water resistivity of less than 500[Ωㆍm]. The phase difference between the current and voltage increases in the range of 200[㎑] to 5[㎒]. Consequently, frequency-dependent performance of grounding systems is closely taler to the soil resistivity, it is necessary to consider the effect of grounding system performance on the frequency and soil resistivity.

Development of the ANN for the Estimation of Earth Parameter and Equivalent Resistivity

Ji Pyeong-Shik,Lee Jong-Pil,Shin Kwan-Woo,Lim Jae-Yoon,Kim Sung-Soo The Korean Institute of Electrical Engineers 2005 KIEE International Transactions on Power Engineeri Vol.a5 No.4

Earth equipments are essential to protect humans and other types of equipment from abnormal conditions. Earth resistance and potential must be restricted within a low value. An estimation algorithm of earth parameters and equivalent resistivity is introduced to calculate reliable earth resistance in this research. The proposed algorithm is based on the relationship between apparent resistances and earth parameters. The proposed algorithm, which approximates the non-linear characteristics of earth by using the Artificial Neural Network (ANN), estimates the earth parameters and equivalent resistivity. The effectiveness of the proposed method is verified with case studies.

Equivalent-circuit Analysis of ITO/Alq3/AlOrganic Light-emitting Diode

Dong-Hoe Chung,Tae Wan Kim 한국전기전자재료학회 2007 Transactions on Electrical and Electronic Material Vol.8 No.3

An ITO/Alq3/Al structure was used to study complex impedance of Alq3 based organic light-emitting diodes. Equivalent circuit was analyzed in a device structure of ITO/Alq3/Al with a thickness layer of Alq3 of 100 nm. The obtained impedance was able to be fitted using equivalent circuit model of parallel combination of resistance Rp and capacitance Cp with a small series resistance of Rs.

Equivalent-circuit Analysis of ITO/Alq₃/Al Organic Light-emitting Diode

Chung, Dong-Hoe,Kim, Tae-Wan The Korean Institute of Electrical and Electronic 2007 Transactions on Electrical and Electronic Material Vol.8 No.3

An $ITO/Alq_3/Al$ structure was used to study complex impedance of $Alq_3$ based organic light-emitting diodes. Equivalent circuit was analyzed in a device structure of $ITO/Alq_3/Al$ with a thickness layer of $Alq_3$ of 100 nm. The obtained impedance was able to be fitted using equivalent circuit model of parallel combination of resistance $R_p$ and capacitance $C_p$ with a small series resistance of $R_s$.

Improved Conductance Method for Determining Interface Trap Density of Metal–Oxide–Semiconductor Device with High Series Resistance

Yang, Hyundoek,Son, Yunik,Choi, Sangmoo,Hwang, Hyunsang The Japan Society of Applied Physics 2005 Japanese journal of applied physics Vol.44 No.46

<P>The existence of series resistance in metal–oxide–semiconductor (MOS) devices can result in both the degradation of capacitance at a high frequency and the decrease in conductance. Using a conventional conductance method that does not consider the series resistance, the interface trap density can be underestimated. We propose an improved conductance method based on an equivalent circuit model including the series resistance. Compared with the conventional method, this new method enables the accurate determination of interface trap density.</P>

고출력 18650 리튬이온 배터리의 발열인자 해석 및 실험적 검증

강태우,유기수,김종훈 전력전자학회 2019 전력전자학회 논문지 Vol.24 No.5

This study shows the feasibility of the parameter of the 1st RC parallel equivalent circuit as a factor of the heat generation of lithium-ion cell. The internal resistance of a lithium-ion cell consists of ohmic and polarization resistances. The internal resistances at various SOCs of the lithium-ion cell are obtained via an electrical characteristic test. The internal resistance is inversely obtained through the amount of heat generated during the experiment. By comparing the resistances obtained using the two methods, the summation of ohmic and polarization resistances is identified as the heating factor of lithium-ion battery. Finally, the amounts of heat generated from the 2C, 3C, and 4C-rate discharge experiments and the COMSOL multiphysics simulation using the summation of ohmic and polarization resistances as the heating parameter are compared. The comparison shows the feasibility of the electrical parameters of the 1st RC parallel equivalent circuit as the heating factor.

다중물리모델 기반 이차전지 열거동 분석에 관한 연구

이수빈(Subin Lee),남윤정(Yoon-Jung Nam),유기수(Kisoo Yoo) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4

리튬이온 전지를 사용하는 전지 모듈/팩에서 열관리는 매우 중요한 문제이다. 이러한 관점에서 본 연구는 모듈/팩단위의 전지 열거동을 엄밀히 예측할 수 있는 발열 모델을 제시하고자 하였다. 이차전지의 열해석을 위하여 열 생성 및 소산에 관련된 리튬 전지 발열요소를 가역열과 비가역열로 구분하여 설명하였다. 비 가역 발열의 경우 등가저항을 기반으로 한 Joule-heating 으로 모델링 하게 되는데 이는 전기화학적반응 계산을 회피하기 위한 것으로 수치계산 부담을 현격히 줄일 수 있다. 이때 전기적인 등가저항은 전기화학분광법에 의하여 결정되는데 본 연구에서는 충전율(SOC)을 등간격으로 나누어 등가저항값의 변화를 살펴보았다. 추가적으로 Bultler-Volmer Equation, Ionic Conduction Equation의 해석적인 접근법을 통하여 등가저항값의 변화를 설명하였으며 실험적으로 구한 값과 비교 분석하였다. 이를 통하여 완전충전 /방전 근방에서 급격한 저항값의 변화는 전극으로의 리튬 삽입(Lithium-intercalation) 저항에 기인한다는 것을 밝혀 내었다. 또한 본 연구에서 개발된 단일 셀에 대한 전기발열모델을 IBC 기법을 적용한 발열량 측정값과 비교 검증하였으며 셀/모듈/팩 열 거동 분석을 수치적, 실험적으로 수행하였다 본 분석을 통하여 등가저항기반 발열모델의 신뢰성이 입증되었으며 리튬 전지 모듈/팩의 열설계시 해당모델의 적용 가능성이 확인되었다. Heat management is a critical issue during the operation of battery modules, packs, and trays. A full-scale analysis model for accurately predicting the thermal behavior of batteries is proposed herein. In this study, the heat generation and dissipation terms were classified for both irreversible and reversible heat. The irreversible heat was formulated according to the Joule-heating model with internal resistance in order to circumvent the calculation of electrochemical reactions that require significant computational loads. The internal resistance in the Joule-heating model was determined via electrochemical impedance spectroscopy (EIS). The electrical equivalent resistance is determined by EIS analysis and, in this study, the change of the value was investigated by equal intervals of SOC. Additionally, an analytical formulation of the resistance was derived from the electrochemical kinetic equations to explain the rapid changes. Analysis revealed that the rapid changes were due to the Li intercalation phenomenon in the electrodes. Thermal analyses were conducted according to the proposed model for Li-ion single cells, and the simulation results exhibited good agreement with the experimental data. In addition, the heat generation model developed in this study was compared and verified with the calorific value measured using the IBC technique, and the cell/module/pack open-air analysis was performed numerically and experimentally. Through this analysis, the reliability of the equivalent resistance-based heating model was verified, and the applicability of the corresponding model was confirmed in the thermal design of the lithium battery module/pack.

EIS를 이용한 아크 금속용사 표면처리기법이 적용된 강재의 콘크리트 내 부식 거동에 관한 실험적 연구

윤창복,박장현,이한승 한국구조물진단유지관리공학회 2020 한국구조물진단유지관리공학회 논문집 Vol.24 No.3

As an experimental study on the corrosion behavior of steel materials to which ATMS method using EIS was applied in concrete, immersion of Ca(OH)2 saturated aqueous solution and NaCl aqueous solution simulating the environment inside concrete The corrosion behavior was tested. The equivalent circuit was derived through the analysis of the Nyquist plot, and the interfacial resistance and the polarization resistance of the Ca(OH)2 aqueous solution were compared, and Al ATMS was the best interfacial resistance and Zn ATMS was the best polarization resistance. After burying ATMS steel material of cement mortar, the initial immersion impedance measurement value was the highest in the Zn ATMS test body in the impedance measurement by the immersion time by immersing it in the NaCl aqueous solution. , Al ATMS test piece has the highest impedance and is highly reliable. This is because Al, which has a high ionization tendency, is continuously oxidized in a strong alkaline environment to form a film and protect the steel from permeation of chlorine ions. EIS를 이용한 아크 금속용사 표면처리기법이 적용된 강재의 콘크리트 내 부식거동에 관한 실험적 연구로서 콘크리트 내부환경을 모사한 Ca(OH)2 포화수용액 침지 및, NaCl 수용액에서의 침지실험을 통해 부식거동을 실험하였다. Nyquist plot의 분석을 통하여 등가회로를 도출하였으며 Ca(OH)2 수용액에서의 계면저항과 분극저항을 비교한 결과 계면저항은 Al ATMS가 가장 우수하였으며 분극저항은 Zn ATMS가 가장 우수한 것으로 나타났다. 시멘트 모르타르에 금속용사 표면처리 된 강재를 매립후 NaCl 수용액에 침지하여 침지 시간에 따른 임피던스 측정에서는 초기 침지 임피던스 측정값은 Zn ATMS시험체가 가장 높았으나 침지 2주후에는 Al ATMS 시험체의 임피던스가 가장 높고 안정적으로 나타났다. 이는 이온화 경향이 높은 Al이 강알칼리 환경에서 지속적으로 산화하며 피막을 형성하였으며, 염소 이온의 침투로부터 강재를 보호하기 때문으로 판단된다.