• 상하수도학회지
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• 제27권4호
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• pp.413-428
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• 2013

In this study, Ant Colony Algorithm(ACO) was used for optimal model. ACO which are metaheuristic algorithm for combinatorial optimization problem are inspired by the fact that ants are able to find the shortest route between their nest and food source. For applying the model to water distribution systems, pipes, tanks(reservoirs), pump construction and pump operation cost were considered as object function and pressure at each node and reservoir level were considered as constraints. Modified model from Ostfeld and Tubaltzev(2008) was verified by applying 2-Looped, Hanoi and Ostfeld's networks. And sensitivity analysis about ant number, number of ants in a best group and pheromone decrease rate was accomplished. After the verification, it was applied to real water network from S water treatment plant. As a result of the analysis, in the Two-looped network, the best design cost was found to $419,000 and in the Hanoi network, the best design cost was calculated to $6,164,384, and in the Ostfeld's network, the best design cost was found to $3,525,096. These are almost equal or better result compared with previous researches. Last, the cost of optimal design for real network, was found for 66 billion dollar that is 8.8 % lower than before. In addition, optimal diameter for aged pipes was found in this study and the 5 of 8 aged pipes were changed the diameter. Through this result, pipe construction cost reduction was found to 11 percent lower than before. And to conclusion, The least cost design model on water distribution system was developed and verified successfully in this study and it will be very useful not only optimal pipe change plan but optimization plan for whole water distribution system.

• Advances in Energy Research
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• 제4권1호
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• pp.47-68
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• 2016

A well designed hybrid power system (HPS) can deliver electrical energy in a cost effective way. In this paper, model for HPS consisting of photo voltaic (PV) module and wind mill as renewable energy sources (RES) and solar lead acid battery as storage device connected to unidirectional grid is developed for peak demand reduction. Life time energy cost of the system is evaluated. One year hourly site condition and load pattern are taken into account for analysing the HPS. The optimal HPS is determined for least life time energy cost subject to the constraints like state of charge of the battery bank, dump load, renewable energy (RE) generation etc. Optimal solutions are also found out individually for PV module and wind mill. These three systems are compared to find out the most feasible combination. The results show that the HPS can deliver energy in an acceptable cost with reduced peak consumption from the grid. The proposed optimization algorithm is suitable for determining optimal HPS for desired location and load with least energy cost.

• 대한전기학회논문지
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• 제41권1호
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• pp.9-17
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• 1992

Proper resource allocation is also a very important topic in power system problems, especially in operation and planning. One such is optimal maintenance problem in operation and planning. Least cost and highest reliability should be the subjects to be pursued. A probabilistic operation simulation model developed recently by authors is applied to the proboem of optimal maintenance scheduling. Three different methods are compared, marginal maintenance cost, levelized risk and maintenance space. The method by the marginal maintenance costs shows the least cost, the highest reliability and the highest maintenance outage rates. This latter characteristics may considerably influence the results of genetation planning, because the usual maintenance outages obtained from the other methods have shown to be lower.

• 한국국방경영분석학회지
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• 제25권1호
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• pp.1-12
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• 1999

The ratio of the nonscheduled air flight transportation is about 49% among the personnel transportation at the Korean Air Force from 1993 to 1997. If an appropriate nonscheduled air flight method is developed, it may considerably achieve a reduction of the transportation cost. The purpose of this paper is to propose the least cost transportation method using the optimization technique. The nonscheduled air flight for the personnel can be classified into three types. The proposed least cost transportation method is tested with a current air flight method for each of three types. It is shown that a proposed method can considerably reduce the transportation cost.

• Journal of Communications and Networks
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• 제18권1호
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• pp.8-18
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• 2016

In this paper, we propose a number of blind equalization approaches for time-varying andmulti-path channels. The approaches employ cost reference particle filter (CRPF) as the symbol estimator, and additionally employ either least mean squares algorithm, recursive least squares algorithm, or $H{\infty}$ filter (HF) as a channel estimator such that they are jointly employed for the strategy of "Rao-Blackwellization," or equally called "mixture filtering." The novel feature of the proposed approaches is that the blind equalization is performed based on direct channel estimation with unknown noise statistics of the received signals and channel state system while the channel is not directly estimated in the conventional method, and the noise information if known in similar Kalman mixture filtering approach. Simulation results show that the proposed approaches estimate the transmitted symbols and time-varying channel very effectively, and outperform the previously proposed approach which requires the noise information in its application.

• 한국전자통신학회논문지
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• 제7권1호
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• pp.53-60
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• 2012

본 논문에서는 실시간 네트워크에서 사용될 개선된 분산 QoS 알고리듬을 제안한다. 이 알고리듬은 DCUR(delay-constrained unicast routing) 알고리듬과 같이 LC(least-cost) 패스나 LD(least-delay) 패스를 사용하고 있지만, 루프를 처리할 때에 DCUR 알고리듬보다도 더 효율적으로 처리한다. 본 알고리듬은 모든 패스를 더욱 더 효율적으로 찾을 수 있다.

• 대한수학회지
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• 제56권2호
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• pp.311-327
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• 2019

The aim of this paper is to extend the applicability of Gauss-Newton method for solving underdetermined nonlinear least squares problems in cases not covered before. The novelty of the paper is the introduction of a restricted convergence domain. We find a more precise location where the Gauss-Newton iterates lie than in earlier studies. Consequently the Lipschitz constants are at least as small as the ones used before. This way and under the same computational cost, we extend the local as well the semilocal convergence of Gauss-Newton method. The new developmentes are obtained under the same computational cost as in earlier studies, since the new Lipschitz constants are special cases of the constants used before. Numerical examples further justify the theoretical results.

• 정보처리학회논문지A
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• 제13A권6호
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• pp.511-516
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• 2006

데이터 그리드는 대용량의 데이터 어플리케이션 처리를 위해 지리적으로 분산되어 있는 저장 자원을 제공한다. 대용량을 처리해야 하는 데이터 그리드 환경에서는 기존 웹 캐싱 정책이나 가상 메모리 캐쉬 교체 정책과는 다른 파일 교체 정책이 필요하다. LRU(Least Recently Used)나 LCB-K(Least Cost Beneficial based on K), EBR(Economic-based cache replacement), LVCT(Least Value-based on Caching Time) 같은 기존의 파일 교체 전략은 파일 교체를 위해 추가적인 자원이 필요하거나 미래를 예측해야한다. 본 논문은 이를 해결하기 위해 파일의 크기에 기반하여 파일 교체를 수행하는 SBR-k(Sized-based replacement-k)을 제안한다. 성능평가 결과 제안한 정책이 기존의 정책보다 더 나은 성능을 나타낸다는 것을 확인하였다.

• 가정과삶의질연구
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• 제15권4호
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• pp.103-124
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• 1997

The purpose of this study was to analyze marriage cost planning and marriage cost for the children. Data were obtained from 306 households with at least one child married within past 5 years in Seoul. There were significant differences in marriage cost planning. The average marriage cost was 46,410,000won. Earned income finance asset child's sex child's marriage type the length of planning whether debts were incurred or not and whether the property was sold for child's marriage were significantly associated with the marriage cost. Finally socio-economic variable and marriage cost planning variables played more imprtant role in determining child's marriage cost than child related variables.

• Nuclear Engineering and Technology
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• 제39권5호
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• pp.655-662
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• 2007

Most decision makers in the electricity industry plan their electric power expansion program by considering only a least cost operation, even when circumstances change with differing complexities. It is necessary, however, to analyze a long-term power expansion plan from various points of view, such as environmental friendliness, benefit of a carbon reduction, and system reliability, as well as least cost operation. The objective and approach of this study is to analyze the proper role of nuclear power in a long-term expansion plan by comparing different scenarios in terms of the system cost changes, $CO_2$ emission reduction, and system reliability in relation to the Business-As-Usual (BAU). The conclusion of this paper makes it clear that the Korean government cannot but expand the nationwide nuclear power program, because an increased energy demand is inevitable and other energy resources will not provide an adequate solution from an economic and sustainability point of view. The results of this analysis will help the Korean government in its long-term resource planning of what kinds of role each electric resource can play in terms of a triangular dilemma involving economics, environmental friendliness, and a stable supply of electricity.