• 한국산림과학회지
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• 제98권3호
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• pp.297-304
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• 2009

본 연구는 국립공원 입장료 폐지 후 탐방수요가 급증한 북한산국립공원의 사회 심리적 수용력을 평가하고 생태적 수용력 관리를 위한 단계별 관리전략 마련을 위해 수행되었다. 현지 설문조사는 2008년 10월 북한산국립공원 탐방객 512명을 대상으로 이루어졌다. 한계효용이론 모델을 이용하여 분석한 결과 북한산국립공원의 1일 사회 심리적 수용력은 약 65,000명으로 추정되었다.

• 조명전기설비학회논문지
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• 제12권3호
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• pp.132-138
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• 1998

최근의 자가발전기를 보유한 대용량 수용가에서는 자체의 전력계통올 안정하게 유지하기 위한 명가 방법으로서 안정도 해석올 통한 계통의 문제점을 파악하는 것은 중요한 과제이다. 본 논문은 전력계통에 있어서 대전력계통(한전계통)측의 3상 단락고장시 고장 지속 시간에 따른 자가 발전을 보유한 수용가 전력계통의 전압에 미치는 영향을 조사 분석한 논문으로 한전계통측의 고장 지속 시간에 따라 수용가 계통의 발전기 및 동기기가 불안정하게 된다. 이러한 불안정현상은 후비보호 계전기(저전압 계전기)의 적절한 시간 설정으로 한전계통과 분리하고 수용가의 부하를 차단하므로써 안정도를 증진시킬 수 있다.

• 경영과학
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• 제32권4호
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• pp.97-108
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• 2015

This study proposes a mathematical model to estimate the economic value of weather forecast service, among which the precipitation forecast service is focused. The value is calculated in terms of users' satisfaction or dissatisfaction resulted from the users' decisions made by using the precipitation probabilistic forecasts and thresholds. The satisfaction values can be quantified by the traditional value score model, which shows the scaled utility values relative to the perfect forecast information. This paper extends the value score concept to a collective value score model which is defined as a weighted sum of users' satisfaction based on threshold distribution in a group of the users. The proposed collective value score model is applied to the picnic scenario by using four hypothetical sets of probabilistic forecasts, i.e., under-confident, over-confident, under-forecast and over-forecast. The application results show that under-confident type of forecasts outperforms the others as a measure of the maximum collective value regardless of users' dissatisfaction patterns caused by two types of forecast errors, e.g., miss and false alarm.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.30-30
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• 2010

The Angle Ring and Cap which is called pressboard are settled at primary and secondary coil winding of 154 kV transformer that can reduce effectively distance of insulation. As it has not manufactured pressboard of Angle Ring and Cap for high voltage grade, insulation components industry especially high voltage transformer has not participate in a competition with worldwide yet. That's why is difficult to make an specialized shape of insulation components of high voltage grade. At first, it is very important to make an utility of deformation manufacturing for high voltage transformer insulation components by itself. Therefore it has finally completed to make an deformation manufacturing utility using an special analysis tools. In this paper, developed insulation components was investigates in tensile strength is introduced.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제2B권3호
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• pp.133-139
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• 2002

In this paper, a prototype of an active auxiliary quasi-resonant DC link (QRDCL) snubber assisted voltage source bidirectional power converter (AC to DC and DC to AC) operating at zero voltage soft-switching (BVS) PWM nlode is presented for a Battery Energy Storage System (BESS). The operating principle of this QRDCL circuit and multifunctional control-based converter system, including PWM inverter mode in which energy flows from the battery bank to the three-phase utility-grid in addition to an active PWM converter mode in which energy flows from the utility-grid to the battery banks are described respectively by the control implementation on the basis of d-q coordinate plane transformation. The multifunctional operation characteristics of this three-phase ZVS PWM bi-directional converter with QRDCL is demonstrated fer a BESS under the power conditioning and processing schemes of energy supply mode and energy storage mode, and compared with a conventional three-phase hard switching PWM bi-directional converter for a BESS. The effectiveness of the three-phase ZVS PWM hi-directional converter with QRDCL is proven via the simulation analysis.

• 한국문헌정보학회지
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• 제36권3호
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• pp.133-153
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• 2002

이 연구는 우리 도서관이 생산해 내고 있는 목록의 현단계를 있는 그대로 조사하고 분석해 봄으로써, 우리 도서관목록의 문제점을 파악하고 향후 도서관목록의 유용성을 증대시킬 수 있는 방안을 모색해 보는데 목적이 있다. 이 과정에서 목록을 생산하는 사서의 관점은 물론이고 목록을 이용하는 최종이용자의 관점을 중시하여 목록의 유용성에 대해 중점적으로 논의하였다. 이를 통해, 과연 우리의 도서관목록이 도서관이용자들에게 지식정보자원에 대한 주요 접근의 경로로서 역할을 제대로 수행하고 있는지 가늠해보고, 목록생산자의 관점과 시각이 어떠한 방향으로 변화해야 하는지에 대한 기초 자료를 제공해 보고자 하였다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권5호
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• pp.278-285
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• 1999

This paper proposes new 12 and 24-pulse rectifier systems using an open-delta auto-connected transformer. This approach employs two static converters to operate it at higher than utility line frequencies and to provide multi-pulse operation. By operating magnetic components at a higher frequency, higher power density can be achieved. A unique feature of the proposed approach is that the magnetic components for the dc-side are also exposed to a higher frequency and these components too are reduced in size. The switching frequency and its harmonic components are absent in the utility input line current. The VA ratings of the transformer and static converter are 0.236/0.292 [pu] and 0.11/0.18 [pu] in 12 and 24-pulse rectifier system, respectively. A finer grade of steel or alternatives can be deployed to increase performance and reduce size further. Analysis, simulations, simulations, design example, and experimental results for a 480[V], 10{kVA] prototype system are presented.

• 전기학회논문지
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• 제61권9호
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• pp.1260-1268
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• 2012

Recently, lack of power reserve margin was observed quite often. In this paper, we studied the method to secure power source for a short time, to cut the utility power peak load, and to reduce the users electricity bills. Emergency diesel generator of an office building is to be converted into a dual-fuel engine generator which is responsible for a portion of the peak load. Compared to the conventional diesel fuel generator, the proposed dual-fuel engine is able to reduce the generation power cost by dual-fuel combustion, and it also mitigates the building's utility power peak load by charging the building's peak load. If the dead resources (a group of emergency dual-fuel engine generators), as a Virtual Power Plant, are operating in peak time, we can significantly reduce future large power development costs. We investigated the current general purpose electricity bills as well as the records of the building electric power usage, and calculated diesel engine generator renovation costs, generation fuel costs, driving conditions, and savings in electricity bills. The proposed dual-fuel engine generation method reduces 18.1% of utility power peak load, and turned out to be highly attractive investment alternative which shows more than 27% of IRR, 76 million won of NPV, and 20~53 months of payback periods. The results of this study are expected to be useful to developing the policy & strategy of the energy department.

• International journal of advanced smart convergence
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• 제10권3호
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• pp.41-50
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• 2021

The purpose of this study is to analyze various energy platforms using data in the US and to suggest directions and implications. Some of the leading energy platforms are selected and analyzed based on the opening platform model. We focus on the case analysis of the US utility companies. In case of the horizontal open platform, Green Button sponsor's 'Connect My Data (CMD)' driven by the government invites the utility companies to jointly develop the sponsor's data solution. In case of the vertical open platform, the certification program 'Share My Data (SMD)' allows backward compatibility, because the technical improvement is minimal. The utility companies benchmark Amazon's three-sided market mediation and prefer platform and category exclusivity. For the former, they have data analytics companies like Enervee, Opower and for the latter, they have electronics manufactures and energy service providers (ESPs) like Distributed Energy Resources (DERs). Based on this US case study, we suggest the energy platforms to open their platform for renewable energy supply, energy conservation, high-efficiency products, and residential DER dissemination. To successfully implement the government's energy transition policy, the US platforms should be benchmarked as a business model. Especially, it is needed for them to coordinate a platform ecosystem. To ensure trust in the products and services offered on the marketplace platform, platform's certification program is helpful.

• 한국터널지하공간학회 논문집
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• 제19권1호
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• pp.29-39
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• 2017

본 연구에서는 3면이 지중과 접하는 형태의 전력구에서 온도상승을 방지하기 위한 환기시스템 설계에 필요한 벽면에서 열전달계수 등 열설계 자료를 수치해석적인 방법으로 검토하였다. 수치해석 모델은 터널 벽체에서의 열전달을 고려하기 위해서 전력구의 터널의 라이닝을 포함하는 것으로 모델링하였으며, 전력구에 설치되는 전력케이블의 발열량(117~468 kW/km), 전력구내 풍속(0.5~4.0 m/s)에 따른 터널내 공기온도 및 벽체온도, 벽체를 통한 발열량을 CFD시뮬레이션에 의해서 구하였다. 또한 해석결과로부터 벽체열전달계수를 계산하고 환기구간의 터널내 공기온도를 유지하기 위한 한계거리를 검토하였다. 벽체표면에서 대류열전달계수는 입구영역에서는 불안정한 변화를 보이나 약 100 m정도의 이후에는 일정한 값에 수렴한다. 터널벽체열전달계수는 풍속에 따라 $3.1{\sim}9.16W/m^2^{\circ}C$정도이며, 이를 무차원식으로 표현하면 $Nu=1.081Re^{0.4927}({\mu}/{\mu}_w)^{0.14}$이 된다. 열저항 해석기법에 의해서 터널내 온도 예측방법을 제시하였으며, 약 3%이내의 편차로 예측이 가능한 것으로 평가되었다.