• 대한산업공학회지
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• 제31권1호
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• pp.10-19
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• 2005

The minimum spanning tree (MST) problem is one of the traditional optimization problems. Unlike the MST, the degree constrained minimum spanning tree (DCMST) of a graph cannot, in general, be found using a polynomial time algorithm. So, finding the DCMST of a graph is a well-known NP-hard problem of importance in communications network design, road network design and other network-related problems. So, it seems to be natural to use evolutionary algorithms for solving DCMST. Especially, when applying an evolutionary algorithm to spanning tree problems, a representation and search operators should be considered simultaneously. This paper introduces a new tree representation scheme and a genetic operator for solving combinatorial tree problem using evolutionary algorithms. We performed empirical comparisons with other tree representations on several test instances and could confirm that the proposed method is superior to other tree representations. Even it is superior to edge set representation which is known as the best algorithm.

• 경영과학
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• 제23권1호
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• pp.75-85
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• 2006

The rectilinear Steiner tree problem (RSTP) is to find a minimum-length rectilinear interconnection of a set of terminals in the plane. It is well known that the solution to this problem will be the minimal spanning tree(MST) on some set Steiner points. The RSTP is known to be NP-complete. The RSTP has received a lot of attention in the literature and heuristic and optimal algorithms have been proposed. A key performance measure of the algorithm for the RSTP is the reduction rate that is achieved by the difference between the objective value of the RSTP and that of the MST without Steiner points. A hybrid evolutionary strategy on RSTP based upon nodes set is presented. The computational results show that the hybrid evolutionary strategy is better than the previously proposed other heuristic. The average reduction rate of solutions from the evolutionary strategy is about 11.14%, which is almost similar to that of optimal solutions.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2006년도 추계학술대회
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• pp.589-598
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• 2006

The rectilinear Steiner tree problem is to find a minimum-length rectilinear interconnection of a set of terminals in the plane. It is well known that the solution to this problem will be the minimal spanning tree (MST) on some set Steiner points. A hybrid evolutionary algorithm is introduced based upon the Prim algorithm. The Prim algorithm for the fitness evaluation requires heavy calculation time. The fitness value of parents is inherited to their child and the fitness value of child is estimated by the inherited structure of tree. We introduce four alternative evolutionary algorithms, Experiment result shows that the calculation time is reduced to 25% without loosing the solution quality by using the fitness estimation.

• 한국정보과학회논문지:소프트웨어및응용
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• 제32권4호
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• pp.268-276
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• 2005

본 논문은 최적 통신 걸침 나무 문제(Optimum Communication Spanning Tree Problem OCST)를 다룬다. 일반적으로, OCST문제는 WP-hard 문제로 알려져 있으며 최근에 Papadimitriou 와 Yannakakis에 의해서 MAX SNP-hard로 밝혀졌다. 그럼에도 불구하고 OCST 문제를 해결하기 위한 기존의 주된 접근법은 polynomial time 알고리즘들 이었다. 본 논문에서는 OCST 문제를 해결하기 위한 진화 알고리즘을 소개한다. 특히, 진화 알고리즘을 어떤 문제에 적용할 때 가장 우선적으로 고려되어야 하는 사항은 해를 어떻게 표현할 것인가 하는 표현법(representation)에 관한 것이다. 따라서 본 논문에서는 기존에 차수 제약 걸침 나무 문제를 해결하기 위해 제안한 표현법의 단점을 개선하는 새로운 표현법을 제안하고 이 표현법을 이용해서 트리(tree)를 만들어 내는 decoding 방법 또한 소개한다. 그리고 제안하는 해 표현법에 맞는 유전 연산자를 찾기 위해 네트워크의 정보 및 부모세대가 지닌 유전 정보를 이용하는 3가지 방법을 실험하였다. 결론적으로, 다양한 실험을 통해서 제안하는 방법이 기존의 방법에 비해 우수한 결과를 보여 준다는 것을 확인할 수 있었다.

• 산업경영시스템학회지
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• 제24권68호
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• pp.21-30
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• 2001

The purpose of this study is to present methods for determining the k most vital arcs (k-MVAs) in the minimum spanning tree problem(MSTP) using evolutionary algorithms. The problem of finding the k-MVAs in MSTP is to find a set of k arcs whose simultaneous removal from the network causes the greatest increase in the total length of minimum spanning tree. Generally, the problem which determine the k-MVAs in MSTP has known as NP-hard. Therefore, in order to deal with the problem of real world the heuristic algorithms are needed. In this study we propose to three genetic algorithms as the heuristic methods for finding the k-MVAs in MSTP. The algorithms to be presented in this study are developed using the library of the evolutionary algorithm framework(EAF) and the performance of the algorithms are analyzed through the computer experiment.

• 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.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제2권1호
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• pp.20-25
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• 2002

This paper presents a genetic programming based evolutionary strategy for on-line adaptive learnable evolvable hardware. Genetic programming can be useful control method for evolvable hardware for its unique tree structured chromosome. However it is difficult to represent tree structured chromosome on hardware, and it is difficult to use crossover operator on hardware. Therefore, genetic programming is not so popular as genetic algorithms in evolvable hardware community in spite of its possible strength. We propose a chromosome representation methods and a hardware implementation method that can be helpful to this situation. Our method uses context switchable identical block structure to implement genetic tree on evolvable hardware. We composed an evolutionary strategy for evolvable hardware by combining proposed method with other's striking research results. Proposed method is applied to the autonomous mobile robots cooperation problem to verify its usefulness.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.254-254
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• 2000

This paper presents a genetic programming based evolutionary strategy for on-line adaptive learnable evolvable hardware. genetic programming can be useful control method for evolvable hardware for its unique tree structured chromosome. However it is difficult to represent tree structured chromosome on hardware, and it is difficult to use crossover operator on hardware. Therefore, genetic programming is not so popular as genetic algorithms in evolvable hardware community in spite of its possible strength. We propose a chromosome representation methods and a hardware implementation method that can be helpful to this situation. Our method uses context switchable identical block structure to implement genetic tree on evolvable hardware. We composed an evolutionary strategy (or evolvable hardware by combining proposed method with other's striking research results. Proposed method is applied to the autonomous mobile robots cooperation problem to verify its usefulness.

• Parasites, Hosts and Diseases
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• 제37권4호
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• pp.197-213
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• 1999

Phylogeny is the evolutionary history of a group or the lineage of organisms and is reconstructed based on morphological, molecular and other characteristics. The genealogical relationship of a group of taxa is often expressed as a phylogenetic tree. The difficulty in categorizing the phylogeny is mainly due to the existence of frequent homoplasies that deceive observers. At the present time, cladistic analysis is believed to be one of the most effective methods of reconstructing a phylogenetic tree. Excellent computer program software for phylogenetic analysis is available. As an example, cladistic analysis was applied for nematode genera of the family Acuariidae, and the phylogenetic tree formed was compared with the system used currently. Nematodes in the genera Nippostrongylus and Heligmonoides were also analyzed, and the validity of the reconstructed phylogenetic trees was observed from a zoogeographical point of view. Some of the theories of parasite evolution were briefly reviewed as well. Coevolution of parasites and humans was discussed with special reference to the evolutionary relationship between Enterobius and primates.

• 한국정보처리학회논문지
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• 제5권3호
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• pp.671-680
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• 1998

화상 회의, 원격 진료 및 교육 시스템, CSCW 등과 같은 그룹 응용을 지원하기 위해서는 망에 의해서 멀티캐스트 기능이 제공되어야 한다. 멀티캐스트 경로배정의 방법으로는 보통 최단 경로 트리 방식과 최소 비용 스타이너 트리를 찾기 위해 유전자 알고리즘을 사용하는 진화적 최적화 방법을 제안하고자 한다. 특히 스타이너 트리를 찾기 위해 유전자 알고리즘을 사용하는 진화적 최적화 방법을 제안하고자 한다. 특히 스타이너 트리의 표현에 있어, 일반적인 유전자 알고리즘에서 사용되는 이진 스트링의 개체 표현 대신 트리를 사용하여 개체를 표현하는 방법을 제안함으로써 최적화의 효율을 개선하는 방식을 보여주며, 또한 기존의 경험적 알고리즘과의 비교를 통하여 진화방식에 의한 최적화가 기존의 방법보다 최적해에 더 가까이 수렴할 수 있음을 보여준다.