• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1371-1374
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• 2002

This paper compares four network con-figurations for using as the logical topology in multi- hop wavelength division multiplexing (WDM) networks. The regular network configurations studied in this paper axe ShuffleNet, de Bruijn graph, hypercube, and Man-hattan street network. Instead of using the weight mean hop distance of node placement problem for comparing optimum logical topology, we introduce a new objective function that includes h and the network cost. It can be seen that the network cost strongly depends on the logical topology selected for the implementation of the network. The objective of this paper is to find an optimum logical topology for WDM networks that gives low as well as low network cost.

• 상하수도학회지
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• 제31권1호
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• pp.51-62
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• 2017

For the asset management of a water pipe network, it would be necessary to understand the extent of the maintenance cost required for the water pipe network for the future. This study would develop a method to draw the optimum cost required for the maintenance of the water pipe network in waterworks facilities to maintain the aim revenue water ratio and to achieve the target revenue water ratio, considering the water service providers' waterworks condition and revenue water ratio comprehensively. This study conducted a survey with 96 water service providers as of the early 2015 and developed models to estimate the optimum maintenance cost of the water pipe network, considering the characteristics of the water service providers. Since the correlation coefficient of all the developed models was higher than 0.95, it turned out that it had significant reliability, which was statistically significant. As a result of applying the developed models to the actual water service providers, it was drawn that increasing revenue water ratio to more than a certain level can reduce the maintenance cost of the water pipe network by a great deal. In other words, it is judged that it would be the most efficient to secure the reliability of waterworks management by increasing the short-term revenue water ratio to more than a certain level and gradually increase the revenue water ratio from the long-term perspective. It is expected that the proposed methodology proposed in this study and the results of the study will be used as a basic research for planning the maintenance of water pipe network or establishing a plan for waterworks facilities asset management.

• 한국경영과학회지
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• 제6권1호
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• pp.25-32
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• 1981

The optimum design problem of a proposed oil pipeline network has been formulated as a zero-one programming model to determine the optimum sizes of pipe and pump which minimize the sum of material costs and operating costs during the 20 years of life span. Applying to a real situation, the problem constitutes an assignment type zero-one programming with 372 zero-one variables and 13 constraints. A heuristic algorithm has been developed based on the modified Petersen algorithm utilizing the special form of the activity matrix. The results showed impressive cost savings of 37 percent of the total cost from the original proposal.

• Journal of Communications and Networks
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• 제9권4호
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• pp.438-445
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• 2007

In this paper, we consider the problem of optimum selection of quality-of-service(QoS) classes in interworking between the networks in a next-generation-network(NGN) environment. After introducing the delay-cost and loss-cost characteristics, we discuss the time-invariant(TI) and time-variant(TV) scenarios. For the TI case, we show that under nearly lossless transmission condition, each network can make its own optimization regardless of other networks. For the TV case, we present sufficient conditions under which the optimum QoS class of each network can be considered fixed with respect to time without considerable degradation in the optimization target. Therefore, under the conditions presented in this paper, the QoS of a flow in each network can be determined solely by considering the characteristics of that network and this QoS class can be held fixed during the flow period.

• Journal of Mechanical Science and Technology
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• 제18권11호
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• pp.1923-1931
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• 2004

Manufacturing of complex surface plates in stern and stem is a major factor in cost of a preliminary ship design by computing process. If these hull plate parts are effectively classified, it helps to compute the processing cost and find the way to cut-down the processing cost. This paper presents a new method to classify surface plates effectively in the preliminary ship design using neural network. A neural-network-based ship hull plate classification program was developed and tested for the automatic classification of ship design. The input variables are regarded as Gaussian curvature distributions on the plate. Various applicable rules of network topology are applied in the ship design. In automation of hull plate classification, two different numbers of input variables are used. By observing the results of the proposed method, the effectiveness of the proposed method is discussed. As a result, high prediction rate was achieved in the ship design. Accordingly, to the initial design stage, the ship hull plate classification program can be used to predict the ship production cost. And the proposed method will contribute to reduce the production cost of ship.

• Journal of applied mathematics & informatics
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• 제31권5_6호
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• pp.907-912
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• 2013

This paper focuses on the situation of optimizing the total cost with m given messages and n network nodes. Associated with each network node, a fixed cost is incurred to the receiver if at least one message is received. The mean and variance of the total costs are obtained. Normal approximation is used. Empirical results showed that the derived method reduces research work substantially.

• 경영과학
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• 제25권2호
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• pp.73-80
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• 2008

The location area planning is to assign cells to the location areas of a wireless communication network in an optimum manner. The two important cost components are cost of location update and cost of paging that are of conflicting in nature; i.e., minimizing the registration cost might increase the search cost. Hence, it is important to find a compromise between the location update and paging operations such that the cost of mobile terminal location tracking cost is a minimum. The complete mobile network is divided into location areas. Each location area consists of a group of cells. In fact this is shown to be an NP-complete problem in an earlier study. In this paper, we use an ant colony optimization method to obtain the best/optimal group of cells for a given a network.

• Water Engineering Research
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• 제1권1호
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• pp.63-74
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• 2000

This paper presents a two- phase search scheme for optimal pipe expansion of expansion of existing water distribution systems. In pipe network problems, link flows affect the total cost of the system because the link flows are not uniquely determined for various pipe diameters. The two-phase search scheme based on stochastic optimization scheme is suggested to determine the optimal link flows which make the optimal design of existing pipe network. A sample pipe network is employed to test the proposed method. Once the best tree network is obtained, the link flows are perturbed to find a near global optimum over the whole feasible region. It should be noted that in the perturbation stage the loop flows obtained form the sample existing network are employed as the initial loop flows of the proposed method. It has been also found that the relationship of cost-hydraulic gradient for pipe expansion of existing network affects the total cost of the sample network. The results show that the proposed method can yield a lower cost design than the conventional design method and that the proposed method can be efficiently used to design the pipe expansion of existing water distribution systems.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2002년도 추계종합학술대회
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• pp.126-131
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• 2002

초고속 통신망의 구축에 있어서 가장 많은 투자를 요구하는 부분이 가입자망의 광대역화이다. 본 논문에서는 가입자망의 구성방식을 조사한 다음, 각 구성방식을 분석한 후 경제성 비교방식을 통하여 최적가입자망을 추출하고자 하였다. 최적의 초고속 가입자망 구축을 위해 노드당 비용측면과, 격자형에서 성형과 링형을 여러 환경에서 측정, 비교ㆍ분석하여 경제적인 면에서 최적의 초고속망 구축방안을 제시하였다.

• 대한전자공학회논문지TC
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• 제47권7호
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• pp.51-58
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• 2010

무선 메쉬 네트워크 (Wireless Mesh Network)는 넓은 지역에 저렴한 비용으로 무선 인터넷 서비스를 제공할 수 있는 기술로 많은 관심을 받고 있다. 하지만 무선 메쉬 네트워크는 게이트웨이 주변 노드로 트래픽이 집중되는 병목현상이 발생하는 문제가 있다. 이러한 병목현상을 해결하기 위해서는 멀티 라디오를 사용하는 무선 메쉬 네트워크 구성이 필요하지만, 무분별한 안테나 설치는 전체 시스템 구축비용의 증가를 초래하게 된다. 이에 본 논문에서는 네트워크 트래픽 용량에 따라 최적화된 메쉬 클러스터 규모를 결정하고, 각 메쉬 라우터의 무선 채널 사용량에 따라 안테나 수의 차등적 배치를 통해 병목 현상 해소 및 시스템 구축비용의 최소화가 가능한 시스템 비용 최적화 모델을 제안한다. 제안 최적화 모델의 성능 분석을 위해 CPLEX를 사용해 사용자 트래픽과 게이트웨이 용량에 따른 네트워크 규모 및 최적의 안테나 수를 결정하는 최적해를 도출하였다. 그 결과 제안된 최적화 모델을 통해 멀티 라디오 무선 메쉬 네트워크 구성 시 병목 현상 해결 및 시스템 구축비용의 현저한 감소를 확인할 수 있었다.