• 경영과학
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• 제20권1호
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• pp.141-148
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• 2003

Vehicle routing problem Is known to be a NP-hard problem, and is traditionally solved by some heuristic approaches. This paper investigates the application of the computer method COMSOAL to the optimal vehicle routing problem. This paper discusses the adaptation of the COMSOAL approach to the known set of simple vehicle routing example problem. The results show that the COHSOAL can be a good possible approach to solve the vehicle routing problem.

• 한국컴퓨터정보학회논문지
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• 제22권9호
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• pp.9-16
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• 2017

The course timetabling problem is a problem assigning a set of subjects to the given classrooms and different timeslots, while satisfying various hard constraints and soft constraints. This problem is defined as a constraint satisfaction optimization problem and is known as an NP-complete problem. Various methods has been proposed such as integer programming, constraint programming and local search methods to solve a variety of course timetabling problems. In this paper, we propose an iterative improvement search method to solve the problem based on constraint programming. First, an initial solution satisfying all the hard constraints is obtained by constraint programming, and then the solution is repeatedly improved using constraint programming again by adding new constraints to improve the quality of the soft constraints. Through experimental results, we confirmed that the proposed method can find far better solutions in a shorter time than the manual method.

• 한국멀티미디어학회논문지
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• 제19권2호
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• pp.443-450
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• 2016

This paper deals with a kind of packing problem of which the goal is to compose one or more templates which will be used to produce the items of different types. Each template consists of a fixed number of slots which are assigned to the different types of items and the production of the items is accomplished by printing the template repeatedly. The objective is to minimize the total number of produced items. This problem is known to be NP-hard. We present a polynomial time approximation algorithm which has a constant approximation ratio. The proposed algorithm is based on the well-known first-fit strategy.

• 대한산업공학회지
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• 제35권1호
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• pp.87-91
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• 2009

In the server disconnection problem, a network with m servers and their users is given and an attacker is to destroy a set of edges to maximize his net gain defined as the total disconnected utilities of the users minus the total edge-destruction cost. The problem is known to be NP-hard. In this paper, we study the server disconnection problem restricted to a ring network. We present an efficient combinatorial algorithm that generates an optimal solution in polynomial time.

• 한국멀티미디어학회논문지
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• 제2권4호
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• pp.451-458
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• 1999

본 논문은 다중 광 네트워크상에서 WDM(Wavelength Division Multiplexing)을 이용한 경로 설정 및 파장 할당문제 즉, RWA문제를 해결하는 새로운 알고리즘을 개발하는데 있다. 현재까지 다중 광 네트워크상의 임의 경로에 파장을 할당하는 문제는 NP-hard 문제[1]로 알려져 있으며 , 또한 다중 광 네트워크상에서 주어진 노드쌍들을 연결하는 각각의 링크에는 서로 다른 파장을 할당해야 한다는 기술상에 제약조건을 안고 있다. 따라서, 본 논문에서 는 주어진 네트워크의 유형을 트리 형태로 한정지어 생각하고, 트리 구조상에서 위의 제약조건을 만족하면서 논문 [7]에서 제안한 이론을 토대로 Divided & Conquer방법을 이용하여 실제 모든 경로에 파장을 할당하는 다항시간 알고리즘을 제안하였다 새롭게 제안한 알고리즘의 분석 결과는 $O(n^4log\; n)$이다.

• 한국인터넷방송통신학회논문지
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• 제19권2호
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• pp.221-227
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• 2019

무기 목표물 배정 문제는 지금까지 다항시간 알고리즘이 제안되지 않는 NP-hard 문제로 알려져 왔다. 그럼에도 불구하고, 본 문제에 대해 가능한 모든 경우수를 검증하는 Brute-Force 법이나 분기한정법으로 최적 해를 구하거나 유전자 알고리즘, 입자군 최적화 등의 인공지능 방법으로 근사 해를 구하는 방법들이 제안되고 있다. 본 논문에서는 단지 무기의 총 대수 k, 무기 종류 수 m, 목표물 개수 n에 대해 O(mn)을 k회 수행하는 O(kmn) 다항시간으로 최적 해를 구하는 알고리즘을 제안하였다. 제안된 알고리즘은 Brute-Force 법에 비해 수행횟수를 최소화 시킬 뿐 아니라 최적해도 구하는 장점을 갖고 있다.

• 한국산업정보학회논문지
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• 제27권2호
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• pp.61-69
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• 2022

다수 에이전트 시스템(Multi-agent system)은 에이전트 각자의 결정으로 최상의 조직화 된 결정을 달성하는 것을 목표로 하는 시스템으로 본 논문에서는 다수 에이전트-다수 작업의 할당 문제를 제시한다. 본 문제는 각 에이전트가 하나의 작업에 할당이 되어 수행하고, 작업 수행에 대한 작업 완료 확률(completion probability)이 있으며 모든 작업의 수행 확률을 최대화하는 할당을 결정한다. 비선형(non-linearity)의 목적함수와 조합 최적화(combinatorial optimization)로 표현되는 본 문제는 NP-hard로, 효과적이면서 효율적인 문제 해결 방법론 제시가 필요하다. 본 연구에서는 한계 이익(marginal gain)의 감소를 의미하는 하위모듈성(submodularity)을 활용한 근사 알고리즘(approximation algorithm)을 제안하고, 확장성(scalability)과 강건성(robustness) 측면에서 우수한 알고리즘임을 이론 및 실험적으로 제시한다.

• 한국철도학회논문집
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• 제9권2호
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• pp.206-211
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• 2006

This thesis presents railroad crew restoring problem, which is to determine the railroad plan allocation. This problem is constructed that determine the sequence of duties that railroad crews have to perform. We analyze characteristic of this problem and railroad industry. It's hard to consider many constraint conditions. We propose Integer Programming model and easy methodology to be considered all given operation rules. This problem is known to be NP-hard. We develop a genetic algorithm, which is proved to be powerful in solving optimization problems. We proposed the effective mathematical model and algorithm about making crew restoring in real industry.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1998년도 추계학술대회 논문집
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• pp.282-285
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• 1998

The purpose of this study is to present a method for determining the k most vital arcs in the maximum flow problem using a heuristic method. Generally, the problem which determine the k most vital arcs in maximum flow problem has known as NP-hard. Therefore, in this study we propose a method for determining all the k most vital arcs in maximum flow problem using a genetic algorithm. The proposed algorithm found all alternatives within shorter time than other heuristic methods. The method presented in this study can determine all the alternatives when there exists other alternative solutions.

• Management Science and Financial Engineering
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• 제19권1호
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• pp.25-28
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• 2013

Consider the inverse bin-packing number problem. Given a set of items and a prescribed number K of bins, the inverse bin-packing number problem, IBPN for short, is concerned with determining the minimum perturbation to the item-size vector so that all the items can be packed into K bins or less. It is known that this problem is NP-hard (Chung, 2012). In this paper, we investigate some special cases of IBPN that can be solved in polynomial time. We propose an optimal algorithm for solving the IBPN instances with two distinct item sizes and the instances with large items.