• Journal of Korean Institute of Industrial Engineers
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• v.24 no.1
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• pp.145-156
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• 1998

In a classical clustering problem, grouping is done on the basis of similarities or distances (dissimilarities) among the elements. Therefore, the objective is to minimize the variance within each group while maximizing the between-group variance among all groups. In this paper, however, a new class of clustering problem is introduced. We call this a laydown grouping problem (LGP). In LGP, the objective is to minimize both the within-group and between-group variances. Furthermore, the problem is expanded to a multi-dimensional case where the two-way minimization process must be considered for each dimension simultaneously for all measurement characteristics. At first, the problem is assessed by analyzing its variance structures and their complexities by conjecturing that LGP is NP-complete. Then, the simulated annealing (SA) algorithm is applied and the results are compared against that from others.

• Journal of the Korean Operations Research and Management Science Society
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• v.18 no.3
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• pp.35-49
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• 1993

The node coloring problem is a problem to color the nodes of a graph using the minimum number of colors possible so that any two adjacent nodes are colored differently. This problem, along with the edge coloring problem, has a variety of practical applications particularly in item loading, resource allocation, exam timetabling, and channel assignment. The node coloring problem is an NP-hard problem, and thus many researchers develop a number of heuristic algorithms. In this paper, we survey and classify those heuristics with the emphasis on how an algorithm orders the nodes and colors the nodes using a determined ordering.

• Bulletin of the Korean Mathematical Society
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• v.46 no.2
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• pp.245-253
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• 2009

A new hard problem called the vector decomposition problem (VDP) was recently proposed by Yoshida et al., and it was asserted that the VDP is at least as hard as the computational Diffie-Hellman problem (CDHP) under certain conditions. Kwon and Lee showed that the VDP can be solved in polynomial time in the length of the input for a certain basis even if it satisfies Yoshida's conditions. Extending our previous result, we provide the general condition of the weak instance for the VDP in this paper. However, when the VDP is practically used in cryptographic protocols, a basis of the vector space ${\nu}$ is randomly chosen and publicly known assuming that the VDP with respect to the given basis is hard for a random vector. Thus we suggest the type of strong bases on which the VDP can serve as an intractable problem in cryptographic protocols, and prove that the VDP with respect to such bases is difficult for any random vector in ${\nu}$.

• Korean Journal of Child Studies
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• v.23 no.2
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• pp.1-16
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• 2002

Path analysis was used to determine variables influencing the creativity of elementary school children. Participants were 213 dyads of 6th-grade children and their parents. the children and their parents responded to questionnaires on children's temperament, depression, self-esteem, self-efficacy, and problem-solving style. Children completed the Torrance Tests of Creative Thinking. Child's problem-solving style and self-efficacy directly affected child's creativity. Child's temperament, depression, self-esteem, self-efficacy, and problem-solving indirectly affected creativity such that child's temperament affected depression, which affected child's self-esteem. Then, child's self-esteem affected child's problem-solving which, in turn, affected child's self-efficacy that directly predicted child's creativity. Both problem-solving and self-efficacy were mediators of child's creativity.

• Journal of the Korean earth science society
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• v.23 no.2
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• pp.180-187
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• 2002

The aim of this study was to investigate the factors affecting earth science problem-solving performances of elementary school pre-service teachers. The participants of the study were 81 students attending an elementary school teacher education university. The instruments of the study were paper-and-pencil tests, questionnaires, and interviews. The tests mainly measured the participants' problem solving abilities in the motions of the moon and the planets. Correlation and multiple regression techniques were used for data analysis. The results demonstrated that the pre-service teachers' problem solving abilities were low. Problem-solving performances were affected by the procedural knowledge, the participants' perception of the past earth science performance, self-efficacy, and the prerequisite declarative knowledge. Contrary to our expectation, the spatial visualization ability was not found to be related to the problem-solving performances. Implications of the study are drawn, and suggestions are made for further research.

• Journal of The Korean Association For Science Education
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• v.15 no.1
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• pp.80-91
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• 1995

This study aims to identify the differences in chemical problem solving process of college students when the amount of information, problem context and the reasoning level were varied. Four students were participated and each student solved the problem by think-aloud method and then interviewed individually. Problem solving stage, ratio of time for each solving stage, solving strategy, misconceptions, and errors were identified and discussed related to the characteristics of problems. And, the relationships of students' belief system about chemistry & chemistry problem solving and problem solving characteristics were also identified.

• Journal of applied mathematics & informatics
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• v.20 no.1_2
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• pp.209-224
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• 2006

This paper presents an optimization model with performance constraints for two kinds of graph elements layout problem. The layout problem is partitioned into finite subproblems by using graph theory and group theory, such that each subproblem overcomes its on-off nature about optimal variable. Furthermore each subproblem is relaxed and the continuity about optimal variable doesn't change. We construct a min-max problem which is locally equivalent to the relaxed subproblem and develop the first order necessary and sufficient conditions for the relaxed subproblem by virtue of the min-max problem and the theories of convex analysis and nonsmooth optimization. The global optimal solution can be obtained through the first order optimality conditions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.5
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• pp.1069-1084
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• 2011

This paper considers an optimal base station clustering problem for designing a mobile (wireless) communication network. For a given network with a set of nodes (base stations), the problem is to optimally partition the set of nodes into subsets (each called a cluster) such that the associated inter-cluster traffic is minimized under certain topological constraints and cluster capacity constraints. In the problem analysis, the problem is formulated as an integer programming problem. The integer programming problem is then transformed into a binary integer programming problem, for which the associated linear programming relaxation is solved in a column generation approach assisted by a branch-and-bound procedure. For the column generation, both a heuristic algorithm and a valid inequality approach are exploited. Various numerical examples are solved to evaluate the effectiveness of the LP (Linear Programming) based branch-and-bound algorithm.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.20 no.3
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• pp.239-247
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• 2013

Purpose: This study was done to investigate the relationship between metacognition, learning flow, and problem solving ability in simulation learning of nursing students and to identify the factors influencing problem solving ability. Methods: The study sample was 136 nursing students. Data were collected from September to November, 2012 using a structured questionnaire on metacognition, learning flow and problem solving ability. Descriptive statistics, Pearson correlation and stepwise multiple regression analysis were used with the SPSS win 20.0 program to analyze the data. Results: There were significant positive correlations between metacognition, learning flow and problem solving ability. Learning flow was a significant factor affecting problem solving ability. These variables accounted for 33% of variance. Conclusion: These results suggest that simulation learning has a positive effect on nursing students' learning outcomes.

• Journal of Korean Elementary Science Education
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• v.19 no.1
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• pp.71-83
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• 2000

This study examined the influences of science project activities based on multiple intelligences on problem solving behaviors of elementary school children. Specifically, the influences of the project activities on the problem solving skills and propensities of the children were investigated. Forty-four fifth graders were selected for the study. They performed the projects and made their products of it during five months on the units of "Weather" and "Our Body" Criteria for assessment of problem solving abilities were determined. The patterns reflected in products of the project activities were examined, then the observation of the subjects' problem solving behaviors and the interviews were performed based on the criteria. The results were analyzed through both of qualitative and quantitative approaches. In these analyses, the implementation of the science projects was found to contribute to the improvement in all sub-factors of problem solving, specially, skills associated with the propensities of problem identification and of the collection, analysis, and synthesis of data significantly increased