• 한국화재소방학회논문지
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• 제31권4호
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• pp.52-58
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• 2017

본 연구에서는 급기가압에 따른 건축물 내부의 공기유동에 대한 수치해석을 수행하고 거실, 부속실 및 계단실 간의 차압분포 및 유동 특성을 분석하였다. 유동 해석은 유효누설면적을 측정하기 위해 제작된 누기율 시험설비에 대하여 수행하였으며, 급기가압에 따른 각 실의 압력 및 유속분포 등을 분석하였다. 본 해석에서 공기의 누설은 유효누설면적을 갖는 얇은 틈새를 방화문과 창문에 위치시키는 방법으로 모사하였다. 이러한 방법을 이용한 해석은 계단실과 부속실 간의 차압에 대한 기존 실험의 결과를 적절히 예측하였다. 해석 결과를 통해 국부적인 누설이 급기가압 제연 설비의 전체적인 유동 패턴 및 압력 분포에 큰 영향을 미치지 않음을 확인하였다. 거실-부속실 문 단면에서의 평균속도가 방연풍속에 대한 국가화재안전기준을 만족하였으나 문의 상부와 같은 국부적인 위치에서 부속실로의 유출이 발생할 수 있음을 확인하였다.

• 대한기계학회논문집A
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• 제41권3호
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• pp.225-232
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• 2017

런너, 흡출관 등 양수발전소 수차 부속기기들에 캐비테이션 침식과 피로 균열 등의 손상 발생과 관련하여 많은 정비 사례들이 보고되고 있다. 양수발전소는 급전, 전력계통 안정 등과 같은 부수적 서비스를 제공한다. 이러한 부수적 서비스는 가이드 베인을 작게 열고 운전하는 저개도율 운전을 반복적으로 자주 수행하게 한다. 이러한 저개도율 운전은 수차 부속기기의 손상을 가속시키는 것으로 경험적으로 알려져 있다. 본 연구에서는 양수발전소의 가이드 베인 저개도율 운전이 수차의 캐비테이션과 피로를 가속시키는 효과를 유한요소 유동/응력 해석 및 피로 해석을 통해 정량적으로 평가한다. 평가 결과, 가이드 베인 개도율이 작을수록 캐비테이션 발생 가능성과 수차 효율 저하 가능성이 증가하며, 런너 블레이드 루트부에 최대 응력값을 증가시킴에도 불구하고 저개도율 운전이 피로수명에 미치는 영향은 미미함을 확인하였다.

• ETRI Journal
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• 제37권2호
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• pp.273-282
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• 2015

Vehicle-to-grid presents a mechanism to meet the key requirements of an electric power system, using electric vehicles (EVs) when they are parked. The most economic ancillary service is that of frequency regulation, which imposes some constraints regarding the period and duration of time the vehicles have to be connected to the grid. The majority of research explores the profitability of the aggregator, while the perspective of the EV fleet owner, in terms of their need for usage of their fleet, remains neglected. In this paper, the optimal allocation of available vehicles on a day-ahead basis using queuing theory and fuzzy multi-criteria methodology has been determined. The proposed methodology is illustrated on the daily scheduling of EVs in an electricity distribution company.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.550-552
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• 2001

The vertically integrated power industry was divided into six generation companies and one market operator, where electricity trading was launched at power exchange. In this environment, the profits of each generation companies are guaranteed according to utilization of their own generation equipments. Especially, the electricity demand shows seasonal and weekly regular pattern, which the some capacity should be provided into ancillary service based on the past demand forecasting error and operating results of electricity market. Namely, if generation cost function is applied to SMP and BLMP as announced the previous day, the available generation capacity of the following day could be optimally distributed, and therefore contract capacity of ancillary service applied to CBP(Cost Based Pool) and TWBP(Two-Way Bidding Pool) is determined. Consequently, it is Possible to use the retained equipments optimally. This paper represents on efficient bidding strategies for generation equipments through the calculation of the contract and the application of each generator cost function based on the past demand forecasting error and market operating data.

• 대한전기학회논문지:전력기술부문A
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• 제51권1호
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• pp.37-44
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• 2002

This Paper suggests reasonable pricing mathod fur Reactive Power in Optimal Power Flow for the system analysis. Under restructuring, not only real power pricing but also reactive power pricing is important for the system analysis and operation. If people just focus on real power pricing, the Generators may no generate reactive power voluntarily, because the Generators may not recover the cost of the reactive power generation. So making a reasonable reactive power pricing is becoming more important than any other time. In this paper, the authors set a Proper Power factor and price the portion of the reactive power that exceeds the power factor using Interior Point Method. By applying this method, the System operator can use this strategy for the analysis of reactive power generation pricing and the Generator can get the motivation to generate reactive power. The author develops fully optimized fast Primal Dual Interior Point Method with sparsity technique and applies this method to Reliability Test System (RTS24) and KEPCO 674 bus system (684 buses. 1279 lines). It shows adaptability and usefulness.

• 한국전자파학회논문지
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• 제23권11호
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• pp.1288-1296
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• 2012

최근 기존의 MSS(Mobile Satellite Service) 대역에 지상망과 위성망의 하이브리드 형태인 ATC(Ancillary Terrestrial Component) 서비스 도입이 추진되고 있다. 새로운 MSS/ATC 서비스 주파수 할당을 위해서는 기존의 지상망에 의한 인접 채널 간섭뿐만 아니라 시스템 자체 내의 인접 채널 간섭 분석이 중요하다. 이에 본 논문에서는 인접 채널 간섭에 의한 ACIR(Adjacent Channel Interference Ratio), 지상 이동국 및 위성 이동 지구국의 수를 파라미터로 하여 업링크에서는 지상 기지국 최소 허용 전력 및 시스템 용량(capacity) 손실, 다운링크에서는 1 빔(beam) 당 1 셀(cell)을 가정하여 MSS/ATC 시스템 용량 손실에 대한 시스템 성능을 평가하였다. MSS/ATC 서비스 주파수 배치에 따른 주파수 공유를 위해 두 가지 시나리오 즉, 5 MHz 및 10 MHz 주파수 간격에 대한 ACIR 기준값을 평가하였으며, 향후 이 기준값에 따른 ATC 서비스 커버리지 및 수신 필터 설계 등이 요구된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.869-871
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• 2005

As deregulated electricity markets are being implemented in different countries, the remuneration of reactive power which contribute to ancillary services is one of the key issues, so it is necessary to evaluate the generator's reactive. In this paper, we focus on the evaluation of reactive power which contributes to reactive power balance. The idea is that the main usages of the reactive power of generator can be divided into two components. First one is physically required amounts for transmitting the real power and the second one is the amounts contributed to support the system, that is, to maintain the voltage profiles. In this paper, the second component is used to evaluate the effective amounts of the reactive power contributed to ancillary service.

• Journal of Forest and Environmental Science
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• 제24권3호
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• pp.127-135
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• 2008

The mission of the Forest Inventory and Analyis (FIA) program of the Forest Service, U.S. Department of Agriculture, is to conduct the national forest inventory of the United States of America for purposes of estimating the area of forest land; the volume, growth, and removal of forest resources; and the health of the forest. Users of FIA data, estimates, and related products include land managers, policy and decision-makers, forest industry, environmental organizations, and university researchers. To accomplish its mission, the FIA program has established a sampling design with an intensity of approximately one permanent plot per 2,400 ha across the entire country. Depending on the region of the country, each plot is remeasured at intervals of five or 10 years. The program releases data annually and reports estimates at the county level for each state every five years. Due to budgetary constraints and natural variability among plot observations, sufficient numbers of plots cannot be measured to satisfy precision guidelines for the estimates of many variables unless the estimation process is enhanced using ancillary data. Classified satellite imagery has been demonstrated to be a source of ancillary data that can be used with stratified estimation techniques to increase the precision of estimates with little corresponding increase in costs. A crucial factor restricting the utility of FIA data is that the exact locations of inventory plots cannot be released to the public. Thus, users are generally not able to obtain estimates for small areas or for their own areas of interest if exact plot locations are required. To compensate, satellite imagery, inventory plot data, and the k-Nearest Neighbors technique are being used to construct Internet-based maps of forest attributes from which estimates for arbitrary user-defined areas of interest may be obtained.

• 한국멀티미디어학회논문지
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• 제20권10호
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• pp.1628-1636
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• 2017

Such as closed caption, ancillary data, electronic program guide(EPG), data broadcasting, and etc, increased data for service convenience cause to degrade video quality of high definition contents. This article propose a method to transfer the closed caption data of video contents without video quality degradation. Video quality degradation does not cause in video compression by the block image insertion of caption data in DTV essential hidden area. Additionally the proposed methods have advantage to synchronize video, audio, and caption from preinserted script without time delay.

• KIEE International Transactions on Power Engineering
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• 제4A권4호
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• pp.262-267
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• 2004

With the advent of electric power systems moving from a vertically integrated structure to a deregulated environment, calculating reactive power service charges has become a new and challenging theme for market operators. This paper examines various methods for reactive power management adopted throughout various deregulated foreign and domestic markets and then proposes an innovative method to calculate reactive power service charges using a reactive power market in a wholesale electricity market. The reactive power market is operated based on bids from the generating sources and it settles on uniform prices by running the reactive OPF programs of the day-ahead electricity market. The proposed method takes into account recovering not only the costs of installed capacity but also the lost opportunity costs incurred by reducing active power output to increase reactive power production. Based on the result of the reactive OPF program, the generators that produce reactive power within the obligatory range do not make payments whereas the generators producing reactive power beyond the obligatory range receive compensation by the price determined in the market. A numerical sample study is carried out to illustrate the processes and appropriateness of the proposed method.