• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.535-538
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• 2005

We report the influence of the threshold voltage and mobility fluctuation in TFT on current mode digital circuit performance. We found that the threshold voltage showed more serious circuit malfunction. We studied new circuit configuration for improvement.

• Journal of the Korean Institute of Telematics and Electronics
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• v.11 no.6
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• pp.16-24
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• 1974

In this paper the method of constructing short and open stable voltage inversion negative immittance converter (VNIC) circuits is proposed according to simplified equivalent models witch consist of a parameter control circuit, and a voltage or a current control circuit. VNIC characteristics can be obtained as gate voltage of common gate connection is controlled by the output of the parameter control circuit corresponding to its input. Constructed circuits are analysed, and the experimental results are compared and cheeked with the calculated results. Errors are found less than 11%. Oscillation behavior of constructed VNIC oscillator is compared with that of negative resistance oscillator.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.6
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• pp.1105-1110
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• 2007

This paper describes an equivalent circuit modeling of 4-port connector system. A coupled transmission line was designed and fabricated, mimicking a 4-port connector system, and then S-parameters were measured using 4 port VNA (Vector Network Analyzer). The S-parameters from measurement and from Full-wave simulator coincided quite nice. By using these S parameters, an equivalent circuit parameters for a 4-port system was obtained. The time domain response from the equivalent circuit model matched to the signals, which was measured using TDR(Time Domain Reflectometry) meter. We were also convinced that there should be enough bandwidth to get a meaningful time domain result from Fourier inverse transformation of the S parameters. In addition, we applied the conversion algorithm to the 4-port connector system, which calculates the S-parameters of a 4 port system using the data from a 2-port VNA with the other ports open. Comparison of the two data, one from measurement and the other one from the conversion algorithm, was made in this manuscript.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.6
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• pp.1103-1108
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• 2010

A grounding electrode has the transient grounding impedance characteristics against lightning surges. So the performance of grounding electrodes should be evaluated as a grounding impedance as well as the ground resistance. The frequency-dependent grounding impedance is varied with the shape and size of grounding electrode and is divided into both inductive and capacitive behaviors. This paper presents a theoretical analysis for the grounding impedance determined by the size of grounding electrode using the distributed parameter circuit model. EMTP and Matlab programs were used in calculating the frequency-dependent grounding impedances of vertical grounding electrodes. It was found that the frequency-dependent grounding characteristics of vertical grounding electrodes are characterized by the distributed parameters which are changed in the dimension of grounding electrodes.

• Journal of Electrical Engineering and Technology
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• v.4 no.4
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• pp.531-537
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• 2009

Lightning has a broad frequency spectrum from DC to a few MHz. Consequently, the high frequency performance of grounding systems for protection against lightning should be evaluated, with the distributed parameter circuit model in a uniform soil being used to simulate grounding impedances. This paper proposes a simulation method which applies the distributed parameter circuit model for the frequency-dependent impedance of vertically driven ground rods by considering multi-layered soil structures where ground rods are buried. The Matlab program was used to calculate the frequency-dependent ground impedances for two ground rods of different lengths. As a result, an increase of the length of ground rod is not always followed by a decrease of grounding impedance, at least at a high frequency. The results obtained using the newly proposed simulation method considering multi-layered soil structures are in good agreement with the measured results.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1077-1078
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• 2006

This paper presents circuit model of catenery in electrified railway system. Most of (a.c.)electrified railway system adopted as AT fed power supply system. This system is fed with twice voltage. It is that AT system can be fed through longer distance. Conventional circuit model of catenary is used T equivalent circuit with lumped parameter. This model may include some problem when traction power supply system is analyzed. In addition, the model with distributed parameter is good for analysis of harmonic and EMI.

• Proceedings of the KIEE Conference
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• summer
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• pp.1079-1081
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• 2004

Linear induction motors are characterized by a large air gap and, as a result, large leakage inductances. Moreover, due to its unslotted structure and the absence of end rings in the secondary part, the equivalent circuit parameter calculation is very difficult. Therefore this paper introduces the new method of equivalent circuit parameter and analyzes dynamics characteristic of single-sided LIM

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1171-1172
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• 2007

This Paper presents circuit model of catenery in electrified railway system. Most of (a.c.)electrified railway system adopted as AT fed power supply system. This system is fed with twice voltage. It is that AT system can be fed through longer distance. Conventional circuit model of catenary is used T equivalent circuit with lumped parameter. This model may include some problem when traction power supply system is analyzed. In addition, the model with distributed parameter is good for analysis of harmonic and EMI

• Proceedings of the KIEE Conference
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• summer
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• pp.412-414
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• 2004

In this paper, a novel algorithm of underground cable fault location based on the analysis of distributed parameter circuit is proposed. The proposed method makes voltage and current equations about core and sheath, and then establishes a function of the fault distance according to the analysis of fault conditions. Finally gets the solution of this function through Newton-Raphson iteration method. The effectiveness of proposed algorithm has been verified by Matlab program, and the cable parameters such as impedance and admittance are from EMTP simulation.

• Journal of information and communication convergence engineering
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• v.6 no.1
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• pp.43-46
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• 2008

This paper proposes an advanced test circuit for detecting the connectivity between a drum ring of laser printer and PCB. The detection circuit of charge sharing is proposed, which minimizes the influences of internal parasitic capacitances. The test circuit is composed of precharge circuit, analog comparator, level shifter. Its functional operation is verified using $0.6{\mu}m$ 3.3V/40V CMOS process parameter by HSPICE. Access time is100ns. Layout of the drum contact test circuit is $465{\mu}m\;{\times}\;117{\mu}m$.