• 전자공학회논문지S
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• 제34S권11호
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• pp.34-42
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• 1997

In this paper, we show an optimal structure of impedance control in high density layouts ina high multilayers PCB. The impedance control in a high multilayers FR-4 PCB is very portant isue because a dielectric layer's thickness is very thin. Especially, odd mode impedance control is more difficult than characteristic impedance control in high multilayers PCB. So, we show an optimal structure of odd mode impedance control in that dielectric thickness is about 0.1mm with limited state and discuss multilayers PCB's for swich circuti pack and backplane in developing algorith scale ATM witching system in next time.

• 전기학회논문지
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• 제62권7호
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• pp.937-942
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• 2013

Equivalent series impedance of high-voltage pulsed power capacitor is one of the important electrical characteristics both for users and for capacitor manufacturers because it may have serious effects on the performance of pulse forming circuits. In this paper, definition of equivalent series impedance and factors which generate equivalent series impedance are reviewed. Theoretical analysis for the calculation of equivalent series impedance based on differential measurement method is described and calculation program has been developed. In order to acquire data which are necessary to calculate equivalent series impedance from discharging current waveform, charging-dischargig controller has been manufactured. Measurement results of equivalent series impedance for high voltage pulsed power capacitor have been given.

• 대한전기학회논문지:전력기술부문A
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• 제48권1호
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• pp.16-21
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• 1999

The analysis of distribution line faults is essential to the proper protections of the power system. A high impedance fault test, which was carried in Korean electric power systems, it was found that a arcing phenomenon occurred during the high level portion of conductor voltage in each cycle. In this paper, we propose a new method for detection of high impedance faults, which uses the arcing fault current difference during high voltage and low voltage portion of conductor voltage waveform. To extract this difference, we diveded one cycle fault current into equal spanned four data windows according to the magnitude of voltage waveform and applied fast fourier transform(FFT) to each data window. The frequency spectrum of current wavefrom in each portion are used as the inputs of neural network and is trained to detect high impedance faults. The proposed method shows improved accuracy when applied to staged fault data and fault-like load.

• 대한전기학회논문지:전력기술부문A
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• 제48권12호
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• pp.1492-1497
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• 1999

High impedance fault(HIF) is defined as fault the general overcurrent relay can not detect or interrupt. Especially when HIF occur in residential areas, energized high voltage conductor results in fire hazard, equipment damage or personal threat. This paper proposes the model of the high impedance fault in transmission line using the ZnO arrester and resistance to be implemented within EMTP. The performance of the proposed model is tested on a typical 154[kV] korean transmission line system under various fault conditions. Wavelet transform is efficient and useful for the detection of high impedance fault in power system, because it uses variable windows according to frequency. In this paper, HIF detection method using wavelet transform can distinguish HIF form similar fault like arcfurance load, capacitor bank switching and line switching.

• KIEE International Transactions on Electrophysics and Applications
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• 제4C권5호
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• pp.207-214
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• 2004

This paper presents the characteristics of transient and effective impulse impedances for deeply driven grounding electrodes used in soil with high resistivity or in downtown areas. The laboratory test associated with the time domain performance of grounding piles subjected to a lightning stroke current has been carried out using an actual-sized model grounding system. The ground impedances of the deeply driven ground rods and grounding pile under impulse currents showed inductive characteristics, and the effective impulse ground impedance owing to the inductive component is higher than the power frequency ground impedance. Both power frequency ground impedance and effective impulse ground impedance decrease upon increasing the length of the model grounding electrodes. Furthermore, the effective impulse ground impedances of the deeply driven grounding electrodes are significantly amplified in impulse currents with a rapid rise time. The reduction of the power frequency ground impedance is decisive to improve the impulse impedance characteristics of grounding systems.

• 한국안전학회지
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• 제31권3호
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• pp.47-52
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• 2016

This paper describes the design and fabrication of high frequency ground impedance measuring system for assessment of grounding system for Lightning protection. The ground impedance measuring system has been designed and fabricated which makes it possible to assess the ground impedance by frequency ranges from 100 Hz to 1 MHz. The effective grounding systems having a very low impedance to electromagnetic disturbance such as lightning surges and noises in microelectronics and high-technology branches are strongly required. In order to analyze the dynamic characteristic of grounding system impedances in lightning and surge protection grounding systems, it is highly desirable to assess the ground impedances as a measure of performance of grounding system in which lightning and switching surge currents with fast rise time and high frequency flow. The measuring system is based on the variable frequency power supply and consists of signal circuit part, main control part, data acquisition and processing unit, and voltage and current probe system. The ground impedance measuring system can be used to assess grounding system during occurrence of lightning.

• 한국지능시스템학회논문지
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• 제9권4호
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• pp.426-435
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• 1999

A high impedance fault(HIF) is one of the serious problems facing the electric utility industry today. Because of the high impedance of a downed conductor under some conditions these faults are not easily detected by over-current based protection devices and can cause fires and personal hazard. In this paper a new method for detection of HIF which uses adaptive neuro-fuzzy inference system (ANFIS) is proposed. Since arcing fault current shows different changes during high and low voltage portion of conductor voltage waveform we firstly divided one cycle of fault current into equal spanned four data windows according to the mangnitude of conductor voltage. Fast fourier transform(FFT) is applied to each data window and the frequency spectrum of current waveform are chosen asinputs of ANFIS after input selection method is preprocessed. Using staged fault and normal data ANFIS is trained to discriminate between normal and HIF status by hybrid learning algorithm. This algorithm adapted gradient descent and least square method and shows rapid convergence speed and improved convergence error. The proposed method represent good performance when applied to staged fault data and HIFLL(high impedance like load)such as arc-welder.

• 한국조명전기설비학회지:조명전기설비
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• 제13권2호
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• pp.212-212
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• 1999

This paper proposed a high impedance fault detection method using a neural network on distribution lines. The v-I characteristic curve was obtained by high impedance fault data tested in various soil conditions. High impedance fault was simulated using EMTP. The pattern of High Impedance Fault on high density pebbles was taken as the learning model, and the neural network was valuated on various soil conditions. The average values after analyzing fault current by FFT of evenr·odd harmonics and fundamental rms were used for the neural network input. Test results were verified the validity of the proposed method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 추계학술대회 논문집 학회본부
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• pp.405-407
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• 1994

In order to provide reliable power service and to prevent a potentail hazard and damage, it is important to detect high impedance fault in power distribution line. This paper presents a neural network based approach for the detection of high impedance faults. A time delay neural network has been selected and trained for the fault currents obtained from field experiments. Detection experiments have been performed with the data from four different high impedance surfaces. Experimental results indicated the feasibility of using TDNN for the detection of high impedance faults.

• 전자공학회논문지SC
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• 제48권3호
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• pp.1-5
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• 2011

본 논문에서는 복수개의 단자를 가지는 고집적 센서 어레이의 임피던스 분석을 위한 임피던스 관계 행렬을 제안한다. 복수의 단자 전압과 전류간의 선형 관계는 임피던스 관계 행렬로 표현되고 이 행렬을 이용하면 임의의 단자간의 임피던스를 간편하게 구할 수 있다. 또한 2-port 임피던스 네트워크에 대해서도 임피던스 관계 행렬을 정의하여 구할 수 있다. 복잡한 임피던스 네트워크를 여러 개의 2-port 임피던스 네트워크로 분할하고 각각의 부 네트워크는 이 표현 관계에 의해 정의되고 해석할 수 있다. 제안된 방법은 많은 수의 임피던스 요소를 가지는 센서 어레이의 임피던스를 해석하는데 간편하고도 효과적으로 사용될 수 있고 이를 입증하는 예제를 제시한다.