• 대한수학회논문집
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• 제13권3호
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• pp.635-642
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• 1998

When an integrated communication system is congested, we may reserve some spaces for non-realtime traffic by discarding a part of realtime traffic. That is sensible because realtime traffic is insensitive to a few losses. Several discarding schemes have been developed including Separate Queue (SQ). Under such schemes, the block loss distribution, i.e., the distribution of the number of losses within a given block which consists of successive data of a type, is important. We derive the block loss distribution of the SQ scheme and modifies the SQ scheme with a threshold.

• 한국통신학회논문지
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• 제24권9A호
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• pp.1306-1313
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• 1999

본 논문은 CDMA PCS 이동통신 시스템의 망 설계를 위하여 거리에 따른 신호 감쇄 현상 분석 모델(변형된 Hata path loss model) 및 통계적 신호 강도 분포 모델(Log-Normal 분포)을 제시한다. 제시된 모델에 대구 산적동 및 수성동 지역의 측정 데이터를 적용하여 이들 지역에서 신호 강도의 세기가 임계치를 초과하는 지역의 백분율을 산출하여 망 설계의 기본 자료로 활용할 수 있도록 하였다.

• 대한전기학회논문지:전력기술부문A
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• 제50권5호
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• pp.241-247
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• 2001

Network reconfiguration in distribution systems is realized by changing the status of sectionalizing switches, and is usually done for loss reduction of load balancing in the system. This paper presents an effective heuristic based switching scheme to solve the distribution feeder loss reduction problem. The proposed algorithm consists of two parts. One is to set up a decision tree to represent the various switching operations available. Another is to apply a proposed technique called cyclic best first search. the proposed algorithm identify the most effective the set of switch status configuration of distribution system for loss reduction. To demonstrate the validity of the proposed algorithm, numerical calculations are carried out the 32, 69 bus system models.

• Journal of Biosystems Engineering
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• 제34권3호
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• pp.183-189
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• 2009

Environmental conditions may cause the quality change of fruits during distribution after harvest. In order to prevent the damage or quality change of fruits for distribution, the characteristic of fruits affected by the environmental conditions such as temperature, humidity under various distribution conditions should be known. This research was performed to analyze how the environmental conditions affect the factors such as weight loss rate and ethylene production of the peach under several distribution conditions. Environmental conditions of the actual distributed route were evaluated and the data obtained from the conditions were used for the simulated environmental tests. Regression models of the weight loss rate and the ethylene production of peach were developed and used in predicting peach quality. The weight loss rate of the peach estimated by the ASHRAE data was shown the higher value on the transportation temperature condition than on the low and room temperature conditions. The weight loss rate and the ethylene production of the peach on the simulated distribution conditions were measured and the measured weight loss rate of peach was the smaller than the theoretically estimated one. The regression models of the weight loss rate and the ethylene production were developed respectively.

• 조명전기설비학회논문지
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• 제21권3호
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• pp.117-124
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• 2007

요즈음과 같은 고유가 시대에 대두되고 있는 분야인 에너지 절감과 관련하여, 본 논문에서는 대단위 전력 수용가 내부의 저압배전 시스템을 특고압으로 변경할 때의 전기에너지의 손실절감에 대해 논하였다. 현재 대수용가에서는 특고압을 수전하여 저압으로 강압하여 각 부하에 전압선로로 전력을 공급하는데, 그 대신에 본 논문에서는 수전한 특고압을 수용가내의 개별 부하 근방까지 직접 가져오고 여기서 저압으로 변환하여 짧은 거리에 위치한 부하들에 전력을 공급할 때 소요되는 대략적인 설비비, 공사비의 증가금액과 선로의 전력손실 감소에 의한 절감 금액을 계산하였다. 또한 초기투자비의 회수 기간을 산정함으로 특고압 배전시스템의 경제성에 대하여 간략히 평가하였다.

• 대한전기학회논문지:전력기술부문A
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• 제48권9호
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• pp.1073-1080
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• 1999

Optimal routing of distribution networks can be attained by keeping the line power capacity limit to handle load requirements, acceptable voltage at customer loads, and the reliability indices such as SAIFI, SAIDI, CAIDI, and ASAI limits. This method is composed of optimal loss reduction and optimal reliability cost reduction. The former is solved relating to the conductor resistance of all alternative routes, and the latter is solved relating to the failure rate and duration of each alternative route. The routing considering optimal loss only and both optimal loss and optimal reliability cost are compared in this paper. The case studies with 10 and 24 bus distribution networks showed that reliability cost should be considered as well as loss reduction to achieve the optimal routing in the distribution networks.

• International Journal of Advanced Culture Technology
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• 제3권2호
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• pp.144-148
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• 2015

The paper presents the estimation of power losses in distribution transformer of Provincial Electricity Authority (PEA) distribution system at Muang district of Suphanburi province in Thailand. Data of 416 power distribution transformers composed of transformer (kVA), load current, no load loss and full load loss which were used for calculating energy losses. It was found that the total energy loss of all transformers is approximately 1,756,380 kWh/year.

• Journal of the Korean Data Analysis Society
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• 제20권6호
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• pp.2747-2757
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• 2018

We consider the MLE (maximum likelihood estimate) and Bayesian estimates of three-parameter bathtub-shaped lifetime distribution based on the progressive type II censoring with binomial removal. Jung, Chung (2018) proposed the three-parameter bathtub-shaped distribution which is the extension of the two-parameter bathtub-shaped distribution given by Zhang (2004). Jung, Chung (2018) investigated its properties and estimations. The maximum likelihood estimates are computed using Newton-Raphson algorithm. Also, Bayesian estimates are obtained under the balanced loss function using MCMC (Markov chain Monte Carlo) method. In particular, BSEL (balanced squared error loss) function is considered as a special form of balanced loss function given by Zellner (1994). For comparing theirs MLEs with the corresponding Bayes estimates, some simulations are performed. It shows that Bayes estimates is better than MLEs in terms of risks. Finally, concluding remarks are mentioned.

• 전기학회논문지P
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• 제66권4호
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• pp.219-223
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• 2017

In this paper, we calculated the losses in the high voltage lines of power distribution system. The losses caused by high voltage lines are calculated using maximum current, resistance, loss factor, and dispersion loss factor. The accurate extraction of these factors are very important to calculate the losses exactly. Thus, the maximum loads are subdivided to regions and calculated monthly for more accurate maximum current calculation. Also, the composite resistance is calculated according to the ratio of the used wire types. In order to calculate the loss factor, the load factors according to the characteristics of each region were calculated. Finally, the losses of the distribution system is calculated by adding the losses by the transformers and the low voltage lines.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.519-521
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• 2000

Network reconfiguration is an operation task, and consists in the determination of the switching operations such to reach the minimum loss conditions of the distribution network. In this paper, an effective heuristic based switch scheme for loss minimization is given for the optimization of distribution loss reduction and a solution approach is presented. The solution algorithm for loss minimization has been developed based on the two stage solution methodology. The first stage of this solution algorithm sets up a decision tree which represent the various switching operations available, the second stage applies a proposed technique called cyclic best first search. Therefore, the solution algorithm of proposed method can determine on-off switch statuses for loss reduction, with a minimum computational effort.