• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.55 no.2
• /
• pp.69-75
• /
• 2006

This paper deals with the optimum design solution on reduction of torque ripple for a Synchronous Reluctance Motor with concentrated winding using response surface methodology. The coupled Finite Elements Analysis (FEA) & Preisach model have been used to evaluate the nonlinear solution. Comparisons are given with characteristics of a SynRM according to the stator winding, slot number, open width of slot, slot depth, teeth width variation in concentrated winding SynRM, respectively. This paper presents an optimization procedure using Response Surface Methodology (RSM) to determine design parameters for reducing torque ripple. RSM has been achieved to use the experimental design method in combination with finite Element Method (FEM) and well adapted to make analytical model for a complex problem considering a lot of interaction of design variables. Moreover, Sequential Quadratic Problem (SQP) method is used to solve the resulting of constrained nonlinear optimization problem.

• Journal of the Korean Society of Combustion
• /
• v.22 no.4
• /
• pp.35-42
• /
• 2017

This case covers the issues related to the operation problem, cause analysis and improvement cases of the FGD that employed the non-leakage type GGH in coal-fired power plant for the first time in Korea. In the Cooler, there was a main problem that the tube is damaged by the ash cutting due to the high velocity of flue gas in the duct and by the weak wear resistance of material. In the Reheater, there was a main problem that the tube was corroded due to chlorine and sulfur in the circumstance of the low temperature. In order to solve those problems, we have improved the Reheater tube and tube fins by coating enamel to reduce corrosion rate.

• Korean System Dynamics Review
• /
• v.3 no.2
• /
• pp.93-112
• /
• 2002

Over the past ten years, a new knowledge-based information society is coming up with a new paradigm shifted from the Industrial Society. According to this paradigm, Korea's policies of informatization on public administration affairs are shaped and promoted by several responsible bodies, including the Ministry of Government administration and Home affairs, the National Computerization Agency, as well as central and local Governments. But most informatization actions, especially standard information system projects, have done separately by the Ministries of central government. Besides, because of the absence of informatization strategy in local governments such as cities, counties, etc., they pursue separately various informatization projects on administration affairs by divisions. It is a critical problem not to manage systematic and unified promotion of information systems policies on administration affairs in local government. As an initial attempt to tackle the problem listed above, by introducing systems thinking this paper puts an effort to find some tentative answers to solve the problem possibly raised about the impact by Standard Information System Policy on which little research has been conducted so far. The findings presented in the paper would perhaps provide some ideas and directions for further study.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.21 no.2
• /
• pp.71-93
• /
• 1996

Selection of appropriate knowledge acquisition and representation techniques is regarded as a major task in the development of expert systems. This depends on the characteristics of problem domains. Expert system builders have often adopted a technique without a formal analysis of application domains. The purpose of this paper is to provide the best knowledge aquisition and representation technique for use in human resource management problem domains. In an attempt to meet this purpose, the conceptual contingency model that suggests the best technique according to managerial decision categories is used as a guidance. In order to determine the priority of managerial decision categories, the Analytic Hierarchy Process and an extended method are proposed.

• Management Science and Financial Engineering
• /
• v.17 no.1
• /
• pp.95-116
• /
• 2011

This paper considers a flowshop scheduling problem where a customer orders multiple products (jobs) from a production facility. The objectives are to minimize makespan and to minimize the sum of order (batch) completion times. The order cannot be shipped unless all the products in the order are manufactured. This problem was motivated by numerous real world problems encountered by a variety of manufacturers. For the makespan objective, we develop an optimal solution procedure which runs in polynomial time. For the sum of order completion time objective, we establish the complexity of the problem including several special cases. Then, we introduce a simple heuristic and find an asymptotically tight worst case bound on relative error. Finally, we conclude the paper with some implications.

• Research in Mathematical Education
• /
• v.15 no.2
• /
• pp.181-196
• /
• 2011

In mathematical modeling tasks, where students are exposed to model-eliciting for real and open problems, students are supposed to formulate and use a variety of mathematical skills and tools at hand to achieve feasible and meaningful solutions using appropriate problem solving strategies. In contrast to problem solving activities in conventional math classes, math modeling tasks call for varieties of mathematical ability including mathematical creativity. Mathematical creativity encompasses complex and compound traits. Many researchers suggest the exhaustive list of criterions of mathematical creativity. With regard to the research considering the possibility of enhancing creativity via math modeling instruction, a quantitative scheme to scale and calibrate the creativity was investigated and the assessment of math modeling activity was suggested for practical purposes.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.6 no.9
• /
• pp.2017-2036
• /
• 2012

Based on the current solutions to the problem of energy hole, this paper proposed a nonuniform node distribution clustering algorithm, NNDC. Firstly, we divide the network into rings, and then have an analysis and calculation on nodes' energy consumption in each ring of the network when clustering algorithm is applied to collect data. We also put forward a scheme of nonuniform node distribution on the basis of the proportion of nodes' energy consumption in each ring, and change nodes' active/hibernating states under density control mechanism when network coverage is guaranteed. Simulation shows NNDC algorithm can satisfyingly balance nodes' energy consumption and effectively avoid the problem of energy hole.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.7 no.8
• /
• pp.224-232
• /
• 1999

Topology optimization has evolved into a very efficient concept design tool and has been incorporated into design engineering processes in many industrial sectors. In recent years, topology optimization has become the focus of structural design community and has been researched and applied widely both in academia and industry. There are mainly tow approaches for topology optimization of continuum structures ; homogenization and density methods. The homogenization method is to compute is to compute an optimal distribution of microstructures in a given design domain. The sizes of the micro-calvities are treated as design variables for the topology optimization problem. the density method is to compute an optimal distribution of an isotropic material, where the material densities are treated as design variables. In this paper, the density method is used to formulate the topology optimization problem. This optimization problem is solved by using an optimality criteria method. Several example problems are solved to show the usefulness of the present approach.

• Proceedings of the Korea Society of Mathematical Education Conference
• /
• 2006.05a
• /
• pp.1-16
• /
• 2006

The purpose of this study is to investigate how fifth and sixth graders recognize average and to find out suggestions for teaching/learning methods of average by examining which difference there is depending on the way of the word problem presentation. To solve these study questions, With the way of the word problem presentation set up as experimental treatment experiment was conducted to analyze these. In conclusion, since students who did not learn the regular course of average values had various informal concepts already, it is needed to consider handling more various concepts of average in order to enable students to expand flexible thoughts. And informal concepts of average students showed were the same or similar to types of formalized concepts and had logicality and propriety in their own way. Compared with fifth graders, sixth graders showed a wide difference in informal concepts of average depending on the way of the word problem presentation.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2018.05a
• /
• pp.328-329
• /
• 2018

The problem of imbalance between supply and demand of fine aggregates in the southeastern region due to the decrease in collection of EEZ(Exclusive Economic Zone) sea sand has been raised. In this paper, the possibility of securing alternative aggregate as a means to solve the problem of fine aggregate shortage in the southeast region was analyzed. As a result of the analysis, the alternative aggregate is easy to manufacture and its quality can be secured. And, it is suitable to use as an aggregate with less environmental burden. In addition, institutional improvement measures are needed for effective utilization and recycling of alternative aggregates.