• 제목/요약/키워드: Minimum cost flow

검색결과 88건 처리시간 0.022초

최소비용문제에서 치명호를 결정하는 방법 (A Method for Determining the Most Vital Arcs in Minimum Cost Flow Problem)

  • 안재근;정호연;박순달
    • 한국국방경영분석학회지
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    • 제25권2호
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    • pp.84-96
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    • 1999
  • The purpose of this paper is to find the most vital arc in the minimum cost flow problem. The most vital arc is the arc whose removal results in the greatest influence in the costs or the amount of demands in a given minimum cost flow network. This problem can be well applied to the conflict situations such as military logistics network or communications network. In this situation, network user wants to know which arcs are the most vital to him so that he can reinforce these arcs against attack, while interdictor wants to destroy these arcs which increase the distance of the shortest path most through the network. When one of arcs is removed from the network of the minimum cost flow problem, two kinds of situations can be occurred ; breaking feasibility and increasing cost. In case of breaking feasibility, the rank of arcs are determined using the amount of modified flow in a related network which is made of modifying the optimal alternative of the minimum cost flow problem. The rank of arcs with the increased costs are determined by using a method which finds the directed cycle with the minimum cost in a related network.

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PCB 설계를 위한 Auction 알고리즘의 수학적 등가와 $\varepsilon$-이완법에 관한 연구 (A Study on the Mathematical Equivalence and $\varepsilon$-Relaxation of Auction Algorithm for PCB Design)

  • 우경환;이용희;임태영;이천희
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2000년도 하계종합학술대회 논문집(2)
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    • pp.213-216
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    • 2000
  • Minimum-cost linear network flow problems could be transformed with equal to assignment problems. Traditional method to solve the linear network flow problems are improved source-cost by transform the simple cycle flow. Auction algorithm could be applied to same element using the initial target price and dispersion calculation. Also, each elements are obtained by $\varepsilon$-relaxation methods. In this paper we proposed; 1)minimum-cost flow problem, 2)minimum-cost flow problem by the mathematical equivalent and 3) extraction $\varepsilon$-relaxation & expand transfer problem with minimum-cost flow. It can be applicant to PCB design by above mentioned.

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분지한정법에 의한 전력계통의 최소비용에 관한 연구 (A Study on Minimum Cost Expansion Planning of Power System by Branch and Bound Method)

  • 송길영;최재석
    • 대한전기학회논문지
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    • 제33권1호
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    • pp.9-16
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    • 1984
  • This paper describes the minimum cost expansion planning which is based on the economical aspect under the various conditions on the power system expansion planning. It presents not only linear cost characteristics analysis but also stepwise cost characteristics analysis which satisfies practical condition in the power system. The latter analysis must be handled by integer programming (IP), because the relation between the cost and the capacity has stepwise characteristics. In order to proceed the latter analysis, the solving procedure is illustrated in detais by using branch and bound method which includes the network flow theory and maximum flow-minimum cut theorem.

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최소비용문제의 해법 효율화와 통합구현 (Performance Improvement and Integrated Implementation for Minimum Cost Flow Problem)

  • 정호연
    • 산업경영시스템학회지
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    • 제20권43호
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    • pp.67-79
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    • 1997
  • In this paper we develop the integrated software that can compare algorithms of the minimum cost flow problem using PC. The chosen algorithms are the network simplex method, dual network simplex method, and out-of-kilter method, which methods correspond to primal, dual, and primal-dual approach respectively. We also present the improved methods obtaining the initial solution to increase the efficiency of algorithms, and experiment results shown the difference between the entering(dropping) selection rules.

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다수상품 유통문제를 위한 내부점 방법에서의 Warm-Start (Warm-Start of Interior Point Methods for Multicommodity Network Flow Problem)

  • 임성묵;이상욱;박순달
    • 경영과학
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    • 제21권1호
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    • pp.77-86
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    • 2004
  • In this paper, we present a methodology for solving the multicommodity network flow problems using interior point methods. In our method, the minimum cost network flow problem extracted from the given multicommodity network flow problem is solved by primal-dual barrier method in which normal equations are solved partially using preconditioned conjugate gradient method. Based on the solution of the minimum cost network flow problem, a warm-start point is obtained from which Castro's specialized interior point method for multicommodity network flow problem starts. In the computational experiments, the effectiveness of our methodology is shown.

최소비용 최대유량 알고리즘에 기반한 구급차의 환자이송 병원 배정 기법의 설계 (Design of a hospital assignment scheme for ambulances based on minimum cost maximum flow algorithm)

  • 이정훈
    • 스마트미디어저널
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    • 제12권9호
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    • pp.72-80
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    • 2023
  • 본 논문에서는 다수의 환자가 발생하여 구급차를 통해 병원으로 이송하여야 하는 경우 최소비용 최대유량 알고리즘에 기반하여 병원을 배정 및 재배정하는 기법을 설계하고 성능을 평가한다. 환자의 증상과 병원들까지의 거리에 의해 플로우 그래프를 생성하는 과정, 링크 용량 수정 과정, 구급차와 병원 매칭 과정 등으로 구성되며 알고리즘 수행시간의 효율성으로 인해 추가환자의 발생이나 병원의 수용능력 변경에도 플로우 그래프 재구성에 의해 재배정을 수행할 수 있다. 프로토타입 구현에 의한 성능 평가 결과 주어진 실험 환경에 대해 제안된 기법은 순차 배정 방식에 비해 24%까지 이송요구시간 불만족을 감소시킬 수 있다.

콘벡스 비용함수를 갖는 점-대-다중점 최소비용 흐름문제 (Point-to-Multipoint Minimum Cost Flow Problem with Convex Cost Function)

  • 박구현;신용식
    • 한국경영과학회지
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    • 제25권4호
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    • pp.15-25
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    • 2000
  • In this paper, we introduce a point-to-multipoint minimum cost flow problem with convex and demand splitting. A source node transmits the traffic along the tree that includes members of the point-to-multipoint connection. The traffic is replicated by the nodes only at branch points of the tree. In order to minimize the sum of arc costs, we assume that the traffic demand can be splitted and transmitted to destination nodes along different trees. If arc cost is linear, the problem would be a Steiner tree problem in networks eve though demand splitting is permitted. The problem would be applied in transmitting large volume of traffic from a serve to clients in Internet environments. Optimality conditions of the problem are presented in terms of fair tree routing. The proposed algorithm is a finite terminating algorithm for $\varepsilon$-optimal solution. convergence of the algorithm is obtained under monotonic condition and strict convexity of the cost function. Computational experiences are included.

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공공차량 경로문제 해법연구 (Public Vehicle Routing Problem Algorithm)

  • 장병만;박순달
    • 한국경영과학회지
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    • 제14권2호
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    • pp.53-66
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    • 1989
  • The Public Vehicle Routing Problem (PVRP) is to find the minimum total cost routes of M or less Public-Vehicles to traverse the required arcs(streets) at least once, and return to their starting depot on a directed network. In this paper, first, a mathematical model is formulated as minimal cost flow model with illegal subtour elimination constraints, and with the fixed cost and routing cost as an objective function. Second, an efficient branch and bound algorithm is developed to obtain an exact solution. A subproblem in this method is a minimal cost flow problem relaxing illegal subtour elimination constraints. The branching strategy is a variable dichotomy method according to the entering nonrequired arcs which are candidates to eneter into an illegal subtour. To accelerate the fathoming process, a tighter lower bound of a candidate subproblem is calculated by using a minimum reduced coast of the entering nonrequired arcs. Computational results based on randomly generated networks report that the developed algorithm is efficient.

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Evolutionary Network Optimization: Hybrid Genetic Algorithms Approach

  • Gen, Mitsuo
    • 한국지능시스템학회:학술대회논문집
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    • 한국퍼지및지능시스템학회 2003년도 ISIS 2003
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    • pp.195-204
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    • 2003
  • Network optimization is being increasingly important and fundamental issue in the fields such as engineering, computer science, operations research, transportation, telecommunication, decision support systems, manufacturing, and airline scheduling. Networks provide a useful way to modeling real world problems and are extensively used in practice. Many real world applications impose on more complex issues, such as, complex structure, complex constraints, and multiple objects to be handled simultaneously and make the problem intractable to the traditional approaches. Recent advances in evolutionary computation have made it possible to solve such practical network optimization problems. The invited talk introduces a thorough treatment of evolutionary approaches, i.e., hybrid genetic algorithms approach to network optimization problems, such as, fixed charge transportation problem, minimum cost and maximum flow problem, minimum spanning tree problem, multiple project scheduling problems, scheduling problem in FMS.

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Sketch Recognition Using LSTM with Attention Mechanism and Minimum Cost Flow Algorithm

  • Nguyen-Xuan, Bac;Lee, Guee-Sang
    • International Journal of Contents
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    • 제15권4호
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    • pp.8-15
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    • 2019
  • This paper presents a solution of the 'Quick, Draw! Doodle Recognition Challenge' hosted by Google. Doodles are drawings comprised of concrete representational meaning or abstract lines creatively expressed by individuals. In this challenge, a doodle is presented as a sequence of sketches. From the view of at the sketch level, to learn the pattern of strokes representing a doodle, we propose a sequential model stacked with multiple convolution layers and Long Short-Term Memory (LSTM) cells following the attention mechanism [15]. From the view at the image level, we use multiple models pre-trained on ImageNet to recognize the doodle. Finally, an ensemble and a post-processing method using the minimum cost flow algorithm are introduced to combine multiple models in achieving better results. In this challenge, our solutions garnered 11th place among 1,316 teams. Our performance was 0.95037 MAP@3, only 0.4% lower than the winner. It demonstrates that our method is very competitive. The source code for this competition is published at: https://github.com/ngxbac/Kaggle-QuickDraw.