• 한국경영과학회지
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• 제20권3호
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• pp.105-122
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• 1995

Based on linear models, the inference about the true measurement x$_{f}$ and the optimal designs x (nx1) for the calibration experiments are considered via Baysian statistical decision analysis. The posterior distribution of x$_{f}$ given the observation y$_{f}$ (qxl) and the calibration experiment is obtained with normal priors for x$_{f}$ and for themodel parameters (.alpha., .betha.). This posterior distribution is not in the form of any known distributions, which leads to the use of a numerical integration or an approximation for the calculation of the overall expected loss. The general structure of the expected loss function is characterized in the form of a conjecture. A near-optimal design is obtained through the approximation nof the conditional covariance matrix of the joint distribution of (x$_{f}$ , y$_{f}$ $^{T}$ )$^{T}$ . Numerical results for the univariate case are given to demonstrate the conjecture and to evaluate the approximation.n.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 B
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• pp.488-490
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• 1995

This paper presents an optimization technique using genetic algorithms(GA) for loss minimization in the distribution network reconfiguration. Determining switch position to be opened for loss minimization in the radial distribution system is a discrete optimization problem. GA is appropriate to solve the multivariable optimization problem and it uses population, not a solution. For this reason, GA is attractive to solve this problem. In this paper, we aimed at finding appropriate open sectionalizing switch position using GA, which can lead to minimum transmission losses.

• Journal of the Korean Data and Information Science Society
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• 제25권6호
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• pp.1549-1555
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• 2014

Consider a p-variate normal distribution ($p-q{\geq}3$, q = rank($P_V$) with a projection matrix $P_V$). Using a simple property of noncentral chi square distribution, the generalized Bayes estimators dominating the James-Stein estimator shrinking towards projection vectors under quadratic loss are given based on the methods of Brown, Brewster and Zidek for estimating a normal variance. This result can be extended the cases where covariance matrix is completely unknown or ${\sum}={\sigma}^2I$ for an unknown scalar ${\sigma}^2$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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• pp.335-337
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• 1998

This paper presents a efficient algorithm for loss reduction of distribution system by automatic sectionalizing switch operation in distribution systems of radial type. Simulated Annealing can avoid escape from local minima by accepting improvements in cost, but the use of this algorithm is also responsible for an excessive computation time requirement. To overcome this major limitation of Simulated Annealing Algorithm, we may use advanced Simulated Annealing Algorithm. Numerical examples demonstrate the validity and effectiveness of the proposed methodology.

• 설비공학논문집
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• 제11권5호
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• pp.579-587
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• 1999

The flow distribution characteristics in a complex duct system have been investigated in this paper by three means, namely experimental measurement, numerical simulation and the Extended T-method analysis. While the exit flow rates predicted by the three-dimensional CFD calculation and those given by the experiment show a close agreement, the results from the one-dimensional Extended T-method are found to differ from the experiment by -22.2% to 26.3% for the various exits. These discrepancies may be attributed to the underlying limitation concerning the fitting loss coefficients, which assume that the flow in front of the fittings is fully developed. It is proposed that, in order to analyse the three-dimensional flow distributions in a complex duct system by one-dimensional analysis such as the Extended T-method, further Improvements to the fitting loss coefficients should be made.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권12호
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• pp.732-738
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• 2004

In this paper, we constructed 13 turns pancake coil and solenoid coil with HTS tape and measured AC losses of the pancake coil. The critical current of the pancake coil and the solenoid coil were 80A and 109A, respectively. To compare measured AC losses of the two coils, we carried out numerical analysis using 2-D FEM program for manufactured coils. This paper presents current density distribution, flux density distribution and AC losses of the pancake coil and the solenoid. As a result, we obtained that current density distribution was closely related to the orientation of magnetic field and distribution of AC losses were also closely related to the perpendicular component of flux density distribution in coil. The calculated AC losses of the two coils showed good agreement with measured AC losses and AC losses of the pancake coil was about 9 times bigger than that of the solenoid coil under the same turns and length.

• Transactions on Electrical and Electronic Materials
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• 제18권6호
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• pp.350-358
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• 2017

Recently, owing to increased interest in low-carbon energy supplies, renewable energy sources such as photovoltaics and wind turbines in distribution networks have received considerable attention for generating clean and unlimited energy. The presence of energy storage systems (ESSs) in the promising field of active distribution networks (ADNs) would have direct impact on power system problems such as encountered in probabilistic distributed generation (DG) model studies. Hence, the optimal procedure is offered herein, in which the simultaneous placement of an ESS, photovoltaic-based DG, and wind turbine-based DG in an ADN is taken into account. The main goal of this paper is to maximize the net present value of the loss reduction benefit by considering the price of electricity for each load state. The proposed framework consists of a scenario tree method for covering the existing uncertainties in the distribution network's load demand as well as DG. The collected results verify the considerable effect of concurrent installation of probabilistic DG models and an ESS in defining the optimum site of DG and the ESS and they demonstrate that the optimum operation of an ESS in the ADN is consequently related to the highest value of the loss reduction benefit in long-term planning as well. The results obtained are encouraging.

• 한국지리정보학회지
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• 제7권2호
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• pp.47-56
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• 2004

본 연구는 강우-유출 침식성 인자의 빈도별에 따른 토양유실량을 평가하고 이롤 바탕으로 유역의 토침칭식 위험지역을 분석하는 것을 목적으로 한다. RUSLE는 토양침식량을 분석하는데 이용하였다. 연구지역은 섬진강 수계의 관촌유역을 선정하였다. 빈도별 강우-유출 침식성인자를 얻기 위하여 39년간의 일일최대 강우량 자료를 이용하였다. 확률강우량은 Normal 분포, Log-Normal 분포, Pearson type III 분포, log-Pearson type III 분포 및 Extreme-I 분포를 이용하였다. 이 중 적합도가 가장 높은 것으로 판단되는 Log-Pearson type III 분포를 채택하였다. Log-Pearson type III 분포는 24시간 확률 강우량을 산정하는데 이용하였고, 빈도별 강우-유출 침식성 인자는 Huff 분포비로 평가하였다. 분석결과 2년빈도에서 200년 빈도까지 토양유실량은 평균 $12.8{\sim}68.0ton/ha{\cdot}yr$로 분석되었다. 유역의 토양유실량 분포를 4개 분류등급으로 구분하여 토양침식 위험지역을 분석하였으며, 침식발생 위험지역으로 판단되는 지역은 분류등급 IV로 하였다. 분류등급 IV의 면적은 $0.01{\sim}5.28km^2$로 전체 농경지 면적의 0.02~9.00%로 나타났다. 특히, 200년빈도의 경우 분류등급 IV에서 밭작물 재배지역이 전체 농경지 면적의 77.1%를 차지하는 것으로 나타났다. 농경지의 경작상태에 따라 토양유실이 큰 영향을 받는 것으로 판단된다.

• 대한기계학회논문집
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• 제15권6호
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• pp.2037-2047
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• 1991

본 연구에서는 재료 결정격자의 기본단위나 결정립의 형상등 가장 기본적인 형태가 6각형이라는 점에 착안하여 취성재료의 파손모델로 부재들의 결손을 이용하는 결손확률모델을 제안하여 부재결손에 따른 각각의 파손 해석모델과 결손확률을 구한다. 그리고 비결손모델에서 구한 기본인장하중을 기초로 하여 해석하고자 하는 하중하에서 각각의 파손해석모델을 모델링하여 유한요소법으로 부재결손에 따른 요소중심에서의 최대주응력을 구하여 이론극한인장강도와의 비와 결손확률로 취성재료의 파손확률을 구한다. 또한 취성정도에 따른 균열길이에 대한 치수 매개변수를 구함으로써 재료강 도 연구에 기초가 되게 한다.

• 한국농공학회논문집
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• 제50권1호
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• pp.13-21
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• 2008

Water losses in irrigation canals are mainly estimated as the sum of conveyance and delivery water loss. The losses occur via the evaporation, infiltration, gate operation and water distribution processing. Recently, the study regarding these water losses are not satisfactory enough, also delivery water loss has not been mainly considered on field design. The objective of this study is to investigate and analyze the volume of water loss in irrigation canals considering condition of actual farm land. A field measurement was performed at four research sites, which are managed by Korea Rural Community & Agriculture Corporation, to evaluate conveyance and delivery water loss for 2 years. The measurement was performed by canal type, size and designed flow using the inflow-outflow method at a major points such as start and end of each canal, derivation point of canal and inlet of paddy fields. Results of this study showed that water loss ratio in lateral canals was bigger than that of main canal unlike current design standard and the loss decrease as flow increase. The total of water loss ratio including conveyance and delivery water loss in several irrigation canals ranged between 33.25 and 45.0%.