• Journal of the Korean Operations Research and Management Science Society
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• v.29 no.2
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• pp.77-95
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• 2004

This paper deals with the process planning of flexible manufacturing systems (FMS) with various flexibilities and multiple objectives. The consideration of the manufacturing flexibility is crucial for the efficient utilization of FMS. The machine, tool, sequence, and process flexibilities are considered In this research. The flexibilities cause to increase the Problem complexity. To solve the process planning problem, an this paper an evolutionary algorithm is used as a methodology. The algorithm is named multiobjective competitive evolutionary algorithm (MOCEA), which is developed in this research. The feature of MOCEA is the incorporation of competitive coevolution in the existing multiobjective evolutionary algorithm. In MOCEA competitive coevolution plays a role to encourage population diversity. This results in the improvement of solution quality and, that is, leads to find diverse and good solutions. Good solutions means near or true Pareto optimal solutions. To verify the Performance of MOCEA, the extensive experiments are performed with various test-bed problems that have distinct levels of variations in the four kinds of flexibilities. The experiments reveal that MOCEA is a promising approach to the multiobjective process planning of FMS.

• Journal of Korean Institute of Industrial Engineers
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• v.27 no.3
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• pp.239-249
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• 2001

Competitive coevolution models, often called host-parasite models, are searching models that imitate the biological coevolution that is a series of reciprocal changes in two competing species. The models are known to be an effective method of solving complex and dynamic problems such as game problems, neural network design problems and constraint satisfaction problems. However, previous models consider only ectoparasites that live on the outside of the host when designing the models, not considering endoparasites that live on the inside of the host. This has a limitation to exploiting some information. In this paper, we develop an artificial adaptation model simulating the process in which hosts coevolve with both ectoparasites and endoparasites. In the model, the endoparasites play important roles as follows. By means of them, we can keep the history on results of previous competition between hosts and parasites, and use endogeneous fitness, not exogeneous. Extensive experiments are carried out to show the coevolution phenomenon and to verify the performance of the proposed model. Nim game problems and neural network problems are used as test-bed problems. The results are reported in this paper.

• Journal of Korean Institute of Industrial Engineers
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• v.28 no.1
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• pp.87-98
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• 2002

A competitive coevolutionary algorithm is a probabilistic search method that imitates coevolution process through evolutionary arms race. The algorithm has been used to solve adversarial problems. In the algorithms, the selection of competitors is needed to evaluate the fitness of an individual. The goal of this study is to compare and analyze several competition strategies in terms of solution quality, convergence speed, balance between competitive coevolving species, population diversity, etc. With two types of test-bed problems, game problems and solution-test problems, extensive experiments are carried out. In the game problems, sampling strategies based on fitness have a risk of providing bad solutions due to evolutionary unbalance between species. On the other hand, in the solution-test problems, evolutionary unbalance does not appear in any strategies and the strategies using information about competition results are efficient in solution quality. The experimental results indicate that the tournament competition can progress an evolutionary arms race and then is successful from the viewpoint of evolutionary computation.

• Journal of Korean Institute of Industrial Engineers
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• v.26 no.2
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• pp.101-109
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• 2000

A competitive coevolutionary algorithm is a probabilistic search method that imitates the biological process that two or more species competitively coevolve through evolutionary arms race. The algorithm has been used to efficiently solve adversarial problems that can be formulated as the search for a solution that is correct over a large space of test cases. We develop an efficient competitive coevolutionary algorithm to solve adversarial problems with high complexity. The algorithm developed in this paper employs three methods: tournament competitions, exchanging of entry fee, and localized coevolution. Analyzed in this paper are the effects of the methods on the performance of the proposed algorithm. The extensive experiments show that our algorithm can progress an evolutionary arms race between competitive coevolving species and then outperforms existing approaches to solving the adversarial problems.

• Korean Journal of Culture and Social Issue
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• v.18 no.1
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• pp.97-110
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• 2012

The sharp decline of fertility in industrialized countries since the 19th century constitutes a major problem for evolutionary approaches to human behavior. Why would people voluntarily reduce their total number of offspring, despite the fact that resources are so abundant in modern times? Here I review three evolutionary hypotheses for low fertility in modern societies, and discuss how the evolutionary perspective could shed new light on solving the problem of low fertility in Korea. Low fertility may be 1) a maladaptive outcome from the mismatch between our ancestral environments and evolutionarily novel environments, 2) a consequence of gene-culture coevolution where traits that reduce genetic fitness can still spread through a population as a result of imitation, especially if the traits are expressed by high-status people, or 3) an adaptation that maximize parents' long-term genetic fitness in knowledge-based industrialized societies where high parental investment is required for rearing competitive offspring. Based on these considerations, I suggest how the evolutionary explanations of low fertility can be applied to increasing the birth rate in Korea.