• 해양환경안전학회지
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• 제3권2호
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• pp.93-103
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• 1997

This paper develops a new heuristic, the Excursion Algorithm(EA), for constructing optimal designs for the experiments related with marine environment. The proposed EA consists of three parts: 1) construction of an initial feasible solution, 2) excursions over a bounded region, and 3) stopping rules. It is the second part that distinguishes the EA from the other existing heuristic methods. It turns out that excursions over a bounded feasible and/or infeasible region is effective in alleviating the risks of being trapped at a local optimum. Since this problem is formulated for the first time thesis, other heuristic algorithms do not exist. Therefore, global optimal solutions are obtained by complete enumeration for some cases, and the performance of the EA is evaluated in terms of solution quality. Computational results show that the proposed EA is effective in finding good(or, in many cases, global) solutions to the constrained optimal experimental design problems.

• 전기학회논문지P
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• 제63권2호
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• pp.61-68
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• 2014

Function of battery bank stores energy for DC load in general, and DC power system of the nuclear power plant is used to supply DC loads for safety- featured instrumentation and control such as inverter, class 1E power system control and indication, and station annunciation. Class 1E DC power system must provide a power for the design basis accident conditions, and adequate capacity must be available during loss of AC power and subsequent safe shutdown of the plant. In present, batteries of Class 1E DC power system of the nuclear power plant uses lead-acid batteries. Class 1E batteries of nuclear power plants in Korea are summarized in terms of specification, such as capacity, discharge rate, bank configuration and discharge end voltage, etc. This paper summarizes standards of determining battery size for the nuclear power plant, and analyzes duty cycle for the class 1E DC power system of nuclear power plant. Then, battery cell size is calculated as 2613Ah according to the standard. In addition, this paper analyzes performance test results during past 13 years and shows performance degradation in the battery bank. Performance tests in 2001 and 2005 represent that entire battery cells do not reach the discharge-end voltage. Howeyer, the discharge-end voltage is reached in 14.7% of channel A (17 EA), 13.8% of channel B (16 EA), 5.2% of channel C (6 EA) and 16.4% of channel D (19 EA) at 2011 performance test. Based on the performance test results analysis and size calculation, battery capacity and degradation by age in Korearn nuclear power plant is discussed and would be used for new design.

• 정보화정책
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• 제29권3호
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• pp.61-81
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• 2022

본 연구에서는 EA에서 제공하는 정보가 공공기관 정보화 사업수행 활동에 어떻게 영향을 주는지 살펴보았다. 분석 대상은 관세청 국가 관세망 및 관련 정보화 사업이며 설문 조사를 활용하였다. EA 정보 제공은 정보의 적절성, 충분성, 일관성으로 정의하고 사업수행 활동은 사업관리, 사업 참여, 의사소통, 요구사항 관리, 인력투입으로 정의하여 항목 간 상관분석을 통해 영향도를 제시하였다. EA에서 제공된 정보와 사업관리 툴의 활용도, 인력투입 적정성과는 유의미한 상관관계를 확인할 수 없었다. 담당 공무원은 제공된 정보가 충분하면 사업수행 중 의사 결정에 긍정적인 효과를 주고, 수행업체는 정보가 일관되게 제공된다면 사업에 필요한 자원을 효율적으로 활용할 수 있음을 확인하였다. 연구 결과는 정보화 사업의 성공적인 진행을 위해 사업이 가진 특성과 함께 발주처의 사업환경을 확인하고, 사업을 수행하는 주체별 핵심 역할에 집중하여 사업수행 전략을 수립하는 것이 사업의 성공에 중요하다는 것을 제시하였다.

• 한국산학기술학회논문지
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• 제14권4호
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• pp.2027-2036
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• 2013

소규모수도시설에서 수질기준을 자주 초과하는 질산성질소(NO3-N)와 불소(F-)를 제거하기 위해 역삼투(RO), 나노여과(NF), 전기흡착(EA), 전기응집(EC) 공정을 비교평가 하였다. RO는 질산성질소 72~92%, 불소 74~85%의 제거율을 나타내었고 NF는 질산성질소 5~15%, 불소는 1%의 제거율을 나타내었다. MWCNT를 코팅한 전극을 이용한 EA의 질산성질소는 99%, 불소는 44% 제거율을 보였다. 구리와 MWCNT 복합물 소결전극을 이용한 EA의 질산성질소는 82%, 불소는 77%의 제거율을 보였으나 구리가 용출되는 문제점이 발견되었다. EC의 질산성질소는 11~46%, 불소는 69~99%을 보였다. 결론적으로 RO는 질산성질소와 불소의 높은 제거율이 가능하나 에너지 비용이 부담된다. EC는 질산성질소와 불소의 효과적인 제거가 가능하나 슬러지 발생 부담이 있다. 반면 MWCNT를 활용한 EA는 전극 제조방법에 따라 제거율에 큰 차이를 보였으며 전극의 지속적 사용을 위한 안전성 확보가 시급한 개선점으로 나타났다.

• 제어로봇시스템학회논문지
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• 제19권10호
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• pp.867-872
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• 2013

Many practical processes in industry have nonlinearities of some forms. One commonly encountered form is actuator saturation which can cause a detrimental effect known as integrator windup. Therefore, a strategy of attenuating the effects of integrator windup is required to guarantee the stability and performance of the overall control system. In this paper, optimal tuning of a PID (Proportional-Integral-Derivative) controller with an anti-windup scheme is presented to enhance the tracking performance of the PID control system in the presence of the actuator saturation. First, we investigate effective anti-windup schemes. Then, the parameters of both the PID controller and the anti-windup scheme are optimally tuned by an EA (Evolutionary Algorithm) such as the IAE (Integral of Absolute Error) is minimized. A set of simulation works on two high-order processes demonstrates the benefit of the proposed method.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3270-3275
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• 2007

DME (Dimethyl Ether, $CH_3OCH_3$) has highly attracted attention as an alternative fuel for transportation, power generation and LPG substitute owing to its easy transportation and cleanliness. This study was conducted to verify the combustion performance and to identify potential problems when DME is fuelled to a gas turbine. GE7EA gas turbine of Pyong-Tak power plant was selected as a target to apply the DME. Combustion tests were conducted by comparing DME with methane, which is a major component of natural gas, in terms of combustion instability, $NO_X$ and CO emissions, and the outlet temperature of the combustion chamber. The results of the performance tests show that DME is very clean but has a low combustion efficiency in low load condition. From the results of the fuel nozzle temperature we have ascertained that DME is easy to flash back, and this property should be considered when operating a gas turbine and retrofitting a burner.

• 한국정밀공학회지
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• 제18권2호
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• pp.206-213
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• 2001

An overlapping decentralized robust EA(eigenstructure assignment) controller is designed for an active suspension system of a vehicle based on a full car model with 7-degree of freedom. Using overlapping decomposition, the full car model is decentralized by two half car models. For each half car model, an effective and disturbance suppressible controller can be obtained by assigning appropriately a left eigenstructure of the system. The performance of the proposed overlapping decentralized robust EA controller is compared with that of a conventional centralized EA controller through computer simulations.

• 한국IT서비스학회지
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• 제5권3호
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• pp.1-23
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• 2006

Today, Organizations should be equipped with flexibility in order to cope with rapidly changing environment in management. By doing so, they are able to grow and obtain their superior competitiveness in highly developed economic arena. Recently, Enterprise Architecture is actively constructed to perform such a change flexibly. In this regard, it is crucial to figure out some risk factors for the organizations that place an order. Besides, it is also important to find out the quality of EA and some risk factors caused by the organizations that receive an order. Lastly, it is absolutely important to verify the relationship between such factors and outcomes of EA. In this aspect, this study will verify risk factors made by the former organizations and investigate the quality of EA and its outcome by proving the said relationship. In doing so, it will suggest an appropriate direction for the companies that will build up or perform EA successfully.

• 한국표면공학회지
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• 제57권2호
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• pp.98-104
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• 2024

In order to overcome the urban heat island effect, highly functional paint is attracting attention as a promising means by shielding heat on the structure (building) surface. When a paint was prepared containing nano-sized silica particles, the heat-insulating performance was relatively higher than that of paints with other sizes. In addition, developed paints showed enhanced properties such as chemical resistance and abrasion resistance test because of the presence of nano-sized silica included in functional paint.

• 한국구조물진단유지관리공학회 논문집
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• 제18권5호
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• pp.34-40
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• 2014

HPFRCC는 물-결합재비 (W/B)가 20%로 상당히 낮고 굵은 골재를 사용하지 않으며, 고분말 혼화재료를 혼입하기 때문에 자기수축이 상당히 크게 발생하여 구조물 적용 시 균열저감대책이 필요하다. 따라서 이 연구에서는 HPFRCC의 수축을 효율적으로 저감시키기 위한 방법으로 수축저감제와 팽창재의 사용을 검토하기 위하여 이들의 단독 또는 병행 혼입률에 따른 역학적 특성과 구속 수축특성을 평가하였다. 구속수축 실험 중에서 링-테스트 (Ring-test)를 통하여 HPFRCC에 사용되는 시멘트에 대하여 중량비로 수축저감제 1%와 팽창재를 7.5%를 병행 사용하였을 경우 압축강도와 인장강도가 크게 저하되지 않으면서도 수축을 가장 효율적으로 저감시킬 수 있는 최적 배합임을 도출하였고 수정된 건조수축 균열실험을 통하여 이를 검증하였다.