• 대한전기학회논문지
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• 제41권5호
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• pp.445-458
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• 1992

As one of the forced cooling method of the underground power transmission system, external water cooled system with trough in tunnel was investigated. This study is performed on thermal analysis for a standard condition to determine the cable transmission current of the underground power transmission system about the cooling facility. A parametric study was performed for the inlet water temperatures, flow rates, the inlet air velocities, flow rates and the cooling spans. This study shows that the cable transmission current varies within the allowable limitation in compliance with the variation of inlet water temperatures and flow rates. It exhibits little variations for the most intervals in compliance with the variation of inlet air temperatures and flows. But, the cable transmission current fast reduces for a specified interval and consequently affects the underground transmission system. As a result, when the actual forced cooling system is designed, the design conditions of inlet air have to be considered as the most important parameters in determination of the cable transmission current.

• Journal of Power Electronics
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• 제4권4호
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• pp.228-236
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• 2004

This paper describes the optimal current-control of a permanent magnet synchronous motor by the use of robust and simple current controllers, based upon the analytical procedure known as the inverse LQ (ILQ) design method. The ILQ design method is a strategy for finding the optimal gains based on pole assignment without solving the Riccati equation. It is very important to keep the motor in robust servo-lock. By experiments and simulations, we will show that the ILQ optimal servo-system with servo-lock is more insensitive at low speeds to variations in armature inductance than the standard PI servo-system. Variations in armature inductance have the greatest influence on the responses of a servo-system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.839-841
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• 2004

IEC 60044-6 (Requirements for protective current transformers for transient performance) was established to Korea Standard (KS C IEC 60044-6 ; Instrument transformers Part 6 ; Requirements for protective current transformers for transient performance) in December 11, 2003. In this paper, requirements, test items and test methods protective current transformers for transient performance.

• 자원ㆍ환경경제연구
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• 제1권1호
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• pp.115-149
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• 1991

In evaluating current environmental protection policy, economists often note that current regulations are more costly than necessary to meet environmental quality standards. While the a priori case can be made that current regulatory approaches entail higher-than-necessary costs to attain environmental standards, there is relatively little empirical evidence to support this claim in Korea. The purpose of this analysis is to supply some of the missing evidence by presenting the results of one study that assesses some of the potential savings associated with implementing economic, rather than command-and-control regulatory approaches to abate one type of air pollution in one region, in Korea, Specifically, the analysis examine the costs of meeting a long-term standard for TSP under the alternative control strategies for stationary sources of TSP in Ulsan Industrial Complex region. The alternative strategies that are considered are current command-and-control and various marketable permit designs. The analysis shows that the most efficient policy of emissions control is economic approaches, supporting results of previous empirical studies conducted in other countries.

• 대한임베디드공학회논문지
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• 제18권1호
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• pp.9-17
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• 2023

This paper relates to the development of a device for measuring the efficiency of a solar panel based on a variable constant current, and proposed a standard for reuse of the solar panel. By applying a variable constant current circuit to a solar panel efficiency measuring device, it was easy to apply a maximum power point tracking (MPPT) algorithm. In addition, a load dispersion method was applied to measure the efficiency of a high-capacity solar panel. and it is possible to solve a problematic thermal runaway during a MOSFET parallel operation by applying the load dispersion method. As a result of the experiment, the solar panel efficiency measuring device was able to accommodate a large solar panel of 350W, which is the maximum measurement goal. In this paper, the validity was confirmed through the 310W solar panel efficiency measurement experiment collected after removal.

• 한국초전도ㆍ저온공학회논문지
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• 제8권2호
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• pp.17-19
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• 2006

A novel clock distribution technique for pipelined-RSFQ logics using variable Bias Currents of JTLs as delay-medium is newly proposed. RSFQ logics consist of several logic gates or blocks connected in a pipeline structure. And each block has variable delay difference. In the structure, this clock distribution method generates a set of clock signals for each logic blocks with suitable corresponding delays. These delays, in the order of few to tens of pS, can be adjusted through controlling bias current of JTL of delay medium. While delays with resistor value and JJ size are fixed at fabrication stage, delay through bias current can be controlled externally, and thus, is heavily investigated for its range as well as correct operation within current margin. Possible ways of a standard delay library with modular structure are sought for further modularizing Pipelined-RSFQ applications. Simulations and verifications are done through WRSpice with Hypres 3-um process parameters.

• 전력전자학회논문지
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• 제18권2호
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• pp.178-183
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• 2013

The study of lightning surge have been conducted on information and communications equipment and power system. However, the research on SMPS itself is an inactive field. This paper analyzes surge current path of flyback converter with the combination wave generator by lightning surge. Also, this paper discloses that there exists the surge current with high-frequency component besides the low-frequency component based on the standard surge current. This high-frequency surge current is the major reason to damage the semiconductor devices such as FET and IC. To confirm the validity of the proposed issue, the analysis and experimental results are presented.

• 한국산업정보학회논문지
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• 제21권1호
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• pp.1-6
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• 2016

본 논문에서는 기생 트랜지스터를 억제하여 대기 전류를 낮춰 기동전류를 개선한 수직 PNP 트랜지스터의 특성을 소개한다. 기생 효과를 억제하기 위해, 회로 변경 없이 "DN+ 링크"를 사용하여 기생 PNP 트랜지스터를 억제 시킨 수직 PNP 트랜지스터를 설계하였으며, 표준 IC 프로세서를 이용한 LDO 레귤레이터를 제작했다. 제작된 기생 PNP 트랜지스터의 hFE 가 기존의 18에서 0.9로 감소하였다. 개선된 "DN+ 링크" 구조 수직 PNP 트랜지스터로 제작된 LDO 레귤레이터의 기동 전류는 기존의 기동 전류 90mA에서 32mA 로 감소되었다. 이로 인해 대기상태에서 저 소비전력을 구현한 LDO 레귤레이터를 개발하였다.

• 한국해양공학회지
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• 제29권2호
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• pp.199-206
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• 2015

Regular high-strength carbon steel is currently the most commonly used pipe material for onshore and offshore pipelines. The corrosion of offshore pipelines is a major problem as they age. The collapse of these structures as a result of corrosion may have a heavy cost is lives and assets. Therefore, their monitoring and screening is a high priority for maintenance, which may ensure the integrity and safety of a structure. Monitoring risers and subsea pipelines effectively can be accomplished using eddy current inspection to detect the average remaining wall thickness of corroded low-alloy carbon steel pipelines through corrosion scaling, paint, coating, and concrete. A test specimen for simulating the offshore pipeline is prepared as a standard specimen for an analysis and experiment with differential bobbin eddy current sensors. Using encircling coils, the signals for the defect in the simulated specimen are analyzed and evaluated in experiments. Differential bobbin eddy current sensors can diagnose the defects in a specimen, and experiments have been carried out using the developed bobbin eddy current sensor. As a result, the most optimum coil parameters were selected for designing differential bobbin eddy current sensors.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.908-910
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• 1998

Modern AC electric car has PWM(Pulse Width Modulation) -controlled converters, which give rise to higher harmonics. The current harmonics injected from AC electric car is propagated through power feeding circuit. As the feeding circuit is a distributed constant circuit composed of RLC, the capacitance of the feeding circuit and the inductance on the side of power system cause a parallel resonance and a magnification of current harmonics at a specific frequency. The magnified current harmonics usually brings about various problems. That is, the current harmonics makes interference in the adjacent lines of communications and the railway signalling system. Furthermore, in case it flows on the side of power system, not only overheating and vibration at the power capacitors but also wrong operation at the protective devices can occur. Therefore, the exact assessment of the harmonic current flow must be undertaken at design and planning stage for the electric traction systems. From these point of view, this study presents an approach to model and to analyse traction power feeding system focused on the amplification of harmonic current. The proposed algorithm is applied to a standard AT(Auto-transformer)-fed test system in which electric car with PWM-controlled converters is running.