• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.5
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• pp.325-331
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• 2004

The multiobjective optimization (MO) problem usually includes the conflicting objectives and the use of conventional optimization algorithms for MO problem does not so good approach to obtain an effective optimal solution. In this paper, genetic algorithm (GA) as an effective method is used to solve such MO problem of brushless DC motor (BLDCM). 3D equivalent magnetic circuit network (EMCN) method which enables us to reduce the computational burden is also used to consider the 3D structure of BLDCM. In order to effectively obtain a set of Pareto optimal solutions in MO problem, ranking method proposed by Fonseca is applied. The objective functions are decrease of cogging torque and increase of torque respectively. The airgap length, teeth width and magnetization angle of PM are selected for the design variables. The experimental results are also shown to confirm the validity of the optimization results.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.1
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• pp.10-15
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• 2012

This paper considers an economic design problem of a tree-based network which is a kind of computer network. This problem can be modeling to be an objective function to minimize installation costs, on the constraints of spanning tree and maximum traffic capacity of sub tree. This problem is known to be NP-hard. To efficiently solve the problem, a tabu list coupled genetic algorithm approach is proposed. Two illustrative examples are used to explain and test the proposed approach. Experimental results show evidence that the proposed approach performs more efficiently for finding a good solution or near optimal solution in comparison with a genetic algorithm approach.

• Journal of the Korea Safety Management & Science
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• v.13 no.1
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• pp.133-142
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• 2011

Overhead facility design problem(OFDP) is one of the shortest rectilinear flow network problem(SRFNP)[4]. Genetic algorithm(GA), artificial immune system(AIS), population management genetic algorithm (PM) and greedy randomized adaptive search procedures (GRASP) were introduced to solve OFDP. A path matrix formed individual was designed to represent rectilinear path between each facility. An exchange crossover operator and an exchange mutation operator were introduced for OFDP. Computer programs for each algorithm were constructed to evaluate the performance of algorithms. Computation experiments were performed on the quality of solution and calculations time by using randomly generated test problems. The average object value of PM was the best of among four algorithms. The quality of solutions of AIS for the big sized problem were better than those of GA and GRASP. The solution quality of GRASP was the worst among four algorithms. Experimental results showed that the calculations time of GRASP was faster than any other algorithm. GA and PM had shown similar performance on calculation time and the calculation time of AIS was the worst.

• Educational Technology International
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• v.19 no.2
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• pp.229-254
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• 2018

Universities in Korea have driven universities' new attempts to adopt more learner-centered and active learning in English. Problem-based Learning (PBL) is one of the well-known constructive teaching and learning methodologies in higher education. Our research goal was to design and develop the optimal PBL practices for a college physics course taught in English to promote learning and course satisfaction. For four semesters, we have tried and adjusted PBL components, and looked at the trend of the exam scores and group work achievement in each semester. We found that the number of problems and the duration of problem solving are the critical factors that influence the effect of PBL in a college physics course taught in English by going through iterative implementation. The iterative process of applying, designing, and constructing PBL to physics classes was meaningful not only in that we have found the optimal PBL model for learning a college physics course, but also in that we have been reflecting on the continuous interaction with learners during the course.

• Educational Technology International
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• v.20 no.1
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• pp.83-107
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• 2019

The aim of this study is to provide the values and descriptive implications of the Design Thinking (DT) method into the context of educational problems of practice in an undergraduate course. To achieve the research objective, both quantitative and qualitative studies were conducted. For the qualitative study, the student's productions and reflections on the experience of the application of the DT into educational problems were analyzed. For the quantitative research, one-group pre and post-test were designed to validate the effectiveness of the DT method into educational contexts in terms of creativity level to measure the student's Creativity Potential and Practiced Creativity, Academic Self-Efficacy Scale, and Problem-Solving Inventory. This study validated that the DT method had a statistically significant influence on those three competencies and also illustrated the detailed process from a qualitative viewpoint. The results and implications reflect the potential of the DT approach with the educational problem of practice, especially, in the ill-structured problem-solving contexts for student-centered instructional setting.

• Korean Journal of Computational Design and Engineering
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• v.4 no.3
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• pp.259-268
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• 1999

In order to reduce the cost of product and save the processing time, optimal nesting of two-dimensional part is an important application in number of industries like shipbuilding and garment making. There have been many studies on finding the optimal solution of two-dimensional nesting. The problem of two-dimensional nesting has a non-deterministic characteristic and there have been various attempts to solve the problem by reducing the size of problem rather than solving the problem as a whole. Heuristic method and linearlization are often used to find an optimal solution of the problem. In this paper, theoretical and practical nesting algorithm for rectangular, circular and irregular shape of two-dimensional parts is proposed. Both No-Fit-Polygon and Minkowski-Sum are used for solving the overlapping problem of two parts and the dynamic programming technique is used for reducing the number search spae in order to find an optimal solution. Also, nesting designer's expertise is complied into the proposed algorithm to supplement the heuristic method.

• Korean Journal of Computational Design and Engineering
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• v.9 no.3
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• pp.226-237
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• 2004

If the topology changes in the re-generation step of the history-based and feature-based CAD systems, it is difficult to identify an entity in the old model and find the same entity in the new model. This problem is known as 'persistent naming problem'. To exchange parametric CAD models, the persistent naming problem and the naming mapping problem must be solved among different CAD system, which use different naming scheme. For CAD model exchange the persistent naming has its own characteristics compare to that for CAD system development. This paper analyses previous researches and proposes a solution to the persistent naming problem for CAD model exchanges and to the naming mapping problem among different naming schemes.

• Journal of Applied Reliability
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• v.13 no.3
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• pp.153-163
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• 2013

QFD(Quality Function Deployment) is a very important tool to improve market share by reducing the gap between the voice of customer and the product's performance. But QFD is not a problem solving tool, although it is very useful in identifying what has to be solved or improved in order to meet the customer's desires. TRIZ has proved to be a very strong tool to solve the difficult problems that requires inventive thinking. QFD integrated with TRIZ becomes hot research recently. But merely linking between HOQ(House of Quality) in QFD and the contradiction matrix in TRIZ can not provide designers with a concrete method to solve the technical problem in the design process. Practically, the contradiction matrix and 40 inventive principles are not helpful for solving the technical problem. To solve the technical problem using TRIZ, a search for the tool and the object involved in the problem is made, from which the wanted result should be derived. A practical method to integrate QFD and TRIZ is proposed in this paper.

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.1
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• pp.13-22
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• 2008

This paper gives reviews on current research status in telecommunication network design. Two problems are identified as major research issues. One is the WDM network design problem, where traffic grooming, virtual topology design and routing and wavelength assignment problems are considered. The other is the OSPF weight setting problem which was proposed as a practical method to implement traffic engineering capability in IP networks. After presenting surveys on those problems, we discuss potential challenging research issues in telecommunication network design.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.141-145
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• 2000

A systematic method to find the optimal blank shape for sheet forming is proposed by coupling the numerical simulation technique. A weighted parameter was introduced in order to simplify the multi-variable optimization problem to a single-variable problem. The proposed method has been applied to the blank design of drawing processes to obtain the near-net shape within the required error bound after forming, Excellent results have been obtained between the numerical results and the target contour shapes. Through the investigation the proposed systematic method for optimal blank design is found to be effective in the practical forming processes