• Journal of the Korean Institute of Telematics and Electronics
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• v.9 no.1
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• pp.17-24
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• 1972

A method utilizing vector representation is investigated for determining a faulty elenlent in passive and active networks by simple external measurements. A large system may be considered as an interconnection of a number of subnetlvorks. By utilizing the relationships between the magintudes of a transfer function at various frequencies and the deviations of a circuit element, the fault simulation curves can be drawn. The fault identification regions are defined from the fault simulation curves. A fault identlfication matrix is constructed corresponding the defined fault identification regions. The fault identification matrix, when premultiplied by a vector whose components are measured from a network, yieldg another vector whose components identify a network element which is faulty. A test procedure for the fault identification method is presented and verified by experiments.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.1
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• pp.45-54
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• 2011

A program aiming at predicting dynamic characteristics of a Liquid Rocket Engine(LRE) was developed and examined to trace entire LRE operation. In the startup period, transient characteristics of the propellant flows were predicted and validated with hydraulic tests data. An arrangement of each component for the pipelines was based on an operating circuit of open cycle LRE. The flow rate ratio for the gas generator and the main chamber was determined to mimic that of real open cycle LRE. Individual component modeling at its transient was completed and was integrated into the system prediction program. Essential parameters of the component dynamic characteristics were examined in an integrated fashion.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.3
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• pp.413-421
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• 2012

This paper proposes the design and implementation of fluid flow generation system by using polypropylene(PP) water capture, which harvests electric energy from the kinetic energy of tidal current or water flow and drives the desired load, and applies it to the discharge drain of Hadong thermal power plant. This experimental system is composed of water captures, driving wheel, gear trains, 10[kW] synchronous generator, and three phase rectifying circuit which drives lamp load for test. The proposed water capturing system which is composed of water captures, rope and driving wheel, rotates as caterpillar according to water flow. This system is very easy to manufacture and more economical than another type of tidal current turbines such as conventional propeller and helical type. Also, we estimated the available fluid flow energy that can be extracted from the cooling water in discharge drain based on drain's cross-sectional area. Therefore, this paper confirms the validity of proposed fluid flow generation system with water captures and the possibility of its application for renewable energy generation in discharge drain of thermal power plant, from the obtained performance characteristic of this energy conversion system.

• Journal of Electrical Engineering and Technology
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• v.3 no.4
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• pp.546-551
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• 2008

In this paper, a flux-lock type superconducting fault current limiter(SFCL) integrated with a voltage-controlled voltage source inverter(VC-VSI) is proposed. The suggested equipment, which consists of a flux-lock type SFCL and a VCVSI, can perform the fault current limiting operation from the occurrence of a short-circuit. In addition, it can compensate the reactive power that the non-linear load requires and also perform the uninterruptible power supply(UPS) as well as the load voltage stabilization by controlling the amplitude and the phase of the inverter's output voltage. The specification for a test model was determined and its various functions such as the fault current limiting and the power conditioning operations were presented and analyzed via computer simulation. Through the analytical results based on the computer simulation, the validity of the analysis was confirmed and its multi-operation was discussed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.6
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• pp.1277-1281
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• 2005

FPGA has been widely used in communication system. In this paper, we made 10 layers PCB on protection of signal noise and data lose with FPGA. We analyzed about change of the data transmission speed and length according to input frequency. The length of transmission line from FPGA's output-pin to output-port on PCB board is 13cm and extended lengths for test are 30cm, 60cm and 10cm. We knew that data can be stably transmitted to 100Mbps at transmission line length of 30cm.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.1012-1016
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• 1998

According to the adoption of inverter circuit topology for welding machine area, the improvement of welding performance can be achieved. However conventional CO2 inverter arc welding machine uses the constant voltage characteristics. So the metal transfer is performed under unoptimum condition in the sence of spatter generation. In this paper the new control algorithm is proposed for welding machine, which is the instantaneous output current control method using single chip microprocessor. But the optimum waveform of welding current is still uncertain, as a first step for figuring out the optimized waveforms, this study was performed. And as a result of performance test of the proposed system, it was demonstrated that all of the waveform variation parameter could be set individually and the generated spatter is reduced compared to conventional inverter arc welding machine.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.838-841
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• 2007

In this study, we implemented a $17^*17b$ binary digital multiplier using radix-4 Booth's algorithm. Two stage pipeline architecture was applied to achieve higher throughput and 4:2 adders were used for regular layout structure in the Wallace tree partition. To evaluate the circuit, several MPW chips were fabricated using Hynix 0.6-um 3M N-well CMOS technology. Also we proposed an efficient test methodology and did fault simulations. The chip contains 9115 transistors and the core area occupies about $1135^*1545$ mm2. The functional tests using ATS-2 tester showed that it can operate with 24 MHz clock at 5.0 V at room temperature.

• Journal of Power Electronics
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• v.18 no.3
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• pp.746-756
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• 2018

Harmonic resonance exists in grid-connected inverter systems. In order to determine the network components that contribute to harmonic resonance and the composition of the resonant circuit, sensitivity theory is applied to the resonance characteristic analysis. Based on the modal analysis, the theory of sensitivity is applied to derive a formula for determining the sensitivities of each network component parameter under a resonance circumstance that reflects the participation of the network component. The solving formula is derived for both parallel harmonic resonance and series harmonic resonance. This formula is adopted to a 4-node grid-connected test system. The analysis results reveal that for a certain frequency, the participation of parallel resonance and series resonance are not the same. Finally, experimental results demonstrate that the solving formula for sensitivity is feasible for grid-connected systems.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.9
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• pp.114-121
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• 2004

Thermal design changes and analysis on the engineering model of Command Telemetry Unit(CTU) for a geostationary communications satellite arc performed for the purpose of developing an engineering qualification model. A thermal model is developed by using power consumption measurement values of each functional board and thermal cycling test results. In modeling heat dissipated EEE parts, heat dissipation is imposed evenly on the EEE part footprint area which is projected to the printed circuit board. All the EEE parts of CTU meet the requirement of their allowable temperature range when placed on the engineering qualification level of thermal vacuum environments in accordance with the proposed thermal design changes.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.10
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• pp.469-475
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• 2003

Resistive leakage current flowing ZnO blocks increases with its ages, which is an important indicator of arrester deterioration. However, a complicated circuitry is essential to measure the resistive leakage current included in the total leakage current, and the difficult handling of the measurement makes few applications to the fields. In this paper, we propose a resistive leakage current measurement device which is composed of a current detection circuit and an analysis program operated on a microprocessor. The device samples the input leakage current waveform digitally, and discriminate the zero-cross and the peak point of the waveform to analyze the current amplitude vs. phase. The capacitive leakage current is then eliminated from the total leakage current by using an algorithm to extract the resistive leakage current only. Also, the device can be operated automatically and manually to analyze the resistive leakage current even when the leakage current waveform is distorted due to various types of arrester deterioration. To estimate the performance of the device, we carried out a test on ZnO blocks and lightning arresters. From the results, it is confirmed that the device could analyze most parameters needed for the arrester diagnostics such as total leakage current. resistive leakage current, and the $3^rd$ harmonic leakage current.