• 한국컴퓨터정보학회논문지
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• 제25권12호
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• pp.55-61
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• 2020

유전자 알고리즘은 명료한 방식으로 답을 찾기 어려운 문제, 즉 NP 문제의 경우 효과적인 솔루션을 찾을 수 있다. 단 유전자 알고리즘의 실행 비용은 기존 프로그래밍 방식에 비하여 높은 비용을 요구하게 되므로, 높은 성능의 실행환경을 전제로 한다. 이러한 문제를 조금이나마 줄여보기 위하여 본 연구는 유전자 알고리즘의 돌연변이 연산자를 초점을 맞추고, 돌연변이 연산의 복잡한 실행을 위한 비용을 고려하여, 과연 해당 연산자가 모든 문제 영역에서 반드시 요구될까를 분석하기 위한 실험을 진행한다. 우리 실험 주체는 유전자 알고리즘을 적용하는 대표적인 문제 중의 하나인 TSP(Travelling Salesman Problem)으로 하였다. 돌연변이 연산을 적용하는 경우와 적용하지 않는 경우에 대한 결과값들을 세대수와 적합도 값을 수집하여 분석한다. 그 결과 돌연변이 연산자를 적용하는 경우가 세대수 감소와 적합도 향상의 효과적인 결과를 반드시 보이지는 않았다.

• Journal of Electrical Engineering and Technology
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• 제11권5호
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• pp.1305-1310
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• 2016

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.311-314
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• 2009

Recently by the development of the electronic engineering technology various mobile devices are developed. But their operation time need to be extended although capacity of the batteries are limited. We focused our attention to the portable SOFC system. Because SOFC has the high efficiency and a lot of strongness in comparison with other kinds of fuel cells, We evaluated hydrogen fed SOFC 50W system theoretically and got the results about the operating condition range from the comparison of the power efficiency, exhaust gas temperature, required heat for maintaining the operation temperature and operation time.

• 전력전자학회논문지
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• 제19권6호
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• pp.549-556
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• 2014

This study proposes a parallel operation strategy for small wind turbine systems. A small wind turbine system consists of blade, permanent magnet synchronous generator, three-phase diode rectifier, DC/DC buck converter, and the battery load. This configuration has reliability, simple control algorithm, high efficiency, and low cost. In spite of these advantages, the system stops when unexpected failures occur. Possible failures can be divided into mechanical and electrical parts. The proposed strategy focuses on the failure of electrical parts, which is verified by numerical analysis through equivalent circuit and acquired general formula of small wind power generation systems. Simulation and experimental results prove its efficiency and usefulness.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.1989-1992
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• 2009

Maintenance is classified preventive maintenance before performing equipment failure and corrective maintenance after performing equipment failure. In preventive maintenance, we may analyze the failure data to end from beginning of equipment and allocate maintenance method and calculate maintenance cycle quantitatively by the failure data analysis. So, it has a merit to reduce system maintenance cost and to operate effectively but, it require high cost in system introducing and continuous operation to end of system. In corrective maintenance, we may calculate MTTR(mean time to repair) quantitatively based on function failure time. it can be based on establishing maintenance system for operation efficiency. In this paper, we may reflect the MTTR for the onboard equipped in Tilting train to establish maintenance system for Tilting train operation efficiency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.2342-2344
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• 2000

Many years ago, most of thermal power plants built in this country were of subcritical pressure, of medium or small size, of constant pressure operation, of drum type steam generator. But, nowadays, almost all of them were of high efficiency, of supercritical pressure, of great capacity(about 500MW), of sliding pressure operation, of once through type steam generator. Presently built once through boiler introduces turbine bypass systems to variable pressure operation which eliminates unexpected materials in boiler tube during startup, minimizes fuel loss by short startup period, eventually improves total efficiency and power system stability

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 추계학술대회 논문집
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• pp.52-53
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• 2015

This paper introduces a novel hybrid converter combining a full-bridge soft switching converter and a full-bridge LLC converter. In this topology all the primary switches can achieve ZVS and ZCS all over the operation range. An additional switch and a diode are added in the secondary side of full-bridge converter to eliminate the circulating current and to provide a separate freewheeling path. The hybrid structure makes it possible to deliver the power to the secondary all the time of operation, thereby improving the efficiency. The proposed topology is suitable for the applications such as on-board chargers for electric vehicles and high power dc-dc converters. A 6.6-kW prototype converter was implemented and 97.5% efficiency was obtained through the experiments.

• 한국환경보건학회지
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• 제19권3호
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• pp.36-40
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• 1993

The objective of this research was to retrofit an on-site sewage treatment system suitable to current situation of Korea to reduce the pollution loading and preserve the invaluable water resources. Operation at the F/M ratio of 0.1 kg. BOD/kg MLSS day showed 87.1% BOD removal efficiency and 84.5% COD removal efficiency, and its effluent concentration was 6.4 mg/l as BOD and 21.7 mg/l as COD. Average removal of total nitrogen showed high removal efficiency of 80%.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.918-923
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• 2011

On AC railway systems, the neutral sections are installed in front of substations and sectioning posts in order to avoid crash between power that have differing phases. In case railway vehicles pass through these neutral sections, it is necessary for them to switch to coasting driving by notch-off. This may reduce speed of the vehicles, resulting lowered train operation efficiency. The usage of automatic power switching systems makes it possible to pass neutral sections at notch-on, enhancing operation efficiency so that it is appropriate for high-speed railway applications. This paper introduces a simulator that assesses efficiency of automatic power switching systems in neutral sections. The is composed of a power supply system, electric railway vehicles, thyristor switches, and traction motors.

• 전력전자학회논문지
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• 제22권1호
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• pp.44-52
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• 2017

This paper describes a 100 kW high-efficiency isolated DC-DC converter for DC distribution system. The DC-DC converter consists of two dual-active-bridge (DAB) converters in parallel. The operating principle of the DAB converter is explained, and the algorithm for parallel operation of the DAB converters is proposed. Simulation and experiments are conducted to verify the performance of the proposed system. Experimental results demonstrate that the developed converter excellently marks 97.4 percent of peak efficiency under its normal operating condition.