• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.11
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• pp.542-548
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• 2000

In this paper, we proposed a new load flow analysis algorithm. In order to develop it, we converted typical power flow problem into optimal problem. This problem has the objective function that minimize the difference between calculated values and specified values of bus powers and subject to bus power equations of P and Q. Using it, we solved the divergence by singularity of Jacobian matrix, the divergence by initial value in the typical power flow study. In the study of a sample system, we verified the superiority of proposed algorithm.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.217-219
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• 1999

This paper presents a study of 2-dimensional(2-D) eddy current problem using boundary element method(BEM). When compared with finite element method(FEM), there are only a few unknown variables in BEM because it implements numerical analysis only for the surface or boundary of a model. As a result, a lot of computational memory and time can be saved. In order to analyze 2-D eddy current problem, potentials and its derivatives(flux) in a boundary are used as variables. The Mantel function of the second kind of the zero order is used here as a fundamental solution. In order to remove singularity and to solve the integral equations in a boundary, Subtracting Singularity Method and Gauss Quadrature Formula are adopted in this paper.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.10a
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• pp.377-386
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• 2000

Hybrid mass dampers consist of passive tuned mass dampers and active mass dampers. They have the advantage that passive tuned mass dampers are still operated even when active mass dampers are stopped by excessive disturbances or power failure. This paper begins first with the comparative analysis of tuned mass dampers, hybrid mass dampers, and active mass dampers. Next more detailed study is carried out on the hybrid mass dampers: cascade hybrid mass dampers (CHMD) and active tuned mass dampers (ATMD). CHMD is regarded as more reasonable device because of its lighter active mass than ATMD's. However CHMD can not neglect stroke saturation problem caused by the length limitation of active damper mass. We compensate the saturation problem with nonlinear restoring force. The restoring force is calculated based on the states and phases of active mass dampers and added to the control force. It is shown that the presented compensation method prevents CHMD from saturation behavior without apparent changes of control force and responses compared to those in case of not considering the saturation problem.

• Structural Engineering and Mechanics
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• v.42 no.1
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• pp.1-12
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• 2012

In this study, Pasternak foundation model, which is a two parameter foundation model, is used to analyze the behavior of laterally loaded beams embedded in semi-infinite media. Total potential energy variation of the system is written to formulate the problem that yielded the required field equations and the boundary conditions. Shear force discontinuities are exposed within the boundary conditions by variational method and are validated by photo elastic experiments. Exact solution of the deflection of the beam is obtained. Both foundation parameters are obtained by self calibration for this particular problem and loading type in this study. It is shown that, like the first parameter k, the second foundation parameter G also depends not only on the material type but also on the geometry and the loading type of the system. On the other hand, surface deflection of the semi infinite media under singular loading is obtained and another method is proposed to determine the foundation parameters using the solution of this problem.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.3-10
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• 2002

This study proposed a technique for inverse problem, linear approximation of contact position and loading in single and double meshing of spur gear, using 2-dimension model considered near the tooth by root stress. Determine root stress is carried out for the gear tooth by finite element method and boundary element method. Boundary element discretization near contact point is carefully performed to keep high computational accuracy. And from those estimated results, the comparing estimate value with boundary element method value was discussed.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.5
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• pp.85-95
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• 2001

This study proposed a technique for inverse problem, linear approximation of contact position and loading in single and double meshing of spiral bevel gear , using 2-dimension model considered near the tooth by root stress. Determine root stress is carried out far the gear tooth by finite element method and boundary element method. Boundary element discretization near contact point is carefully performed to keep high computational accuracy. And from those estimated results, the comparing estimate value with boundary element method value was discussed.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.5
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• pp.24-33
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• 2003

This study proposed a technique for inverse problem, linear approximation of contact position and loading in single and double meshing of transmission contact element using 2-dimension model considered near the tooth by root stress. Determination of root stress is carried out far the gear tooth by finite element method and boundary element method. Boundary element discretization near contact point is carefully performed to keep high computational accuracy. The predicted results of boundary element method are good accordance with that of finite element method.

• Korean Journal of Child Studies
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• v.21 no.2
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• pp.157-169
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• 2000

This study investigated the effects on interpersonal cognitive problem-solving skill of discussion with children of moral conflicts in traditional fairy tales. The subjects were forty 4-to 5-year-old children. The experimental group took part in discussion after hearing traditional fairy tales showing moral conflict, and the control group only listened to the fairy tales. Statistical analysis was by the SAS program. Conclusions were that discussion of moral conflicts found in traditional fairy tales brings about a positive result in children's interpersonal cognitive problem-solving skill.

• Journal of the Korea Society of Computer and Information
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• v.20 no.11
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• pp.119-126
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• 2015

CDSS provides clinical doctors with knowledge to be required when they diagnose or make decision about treatment strategy. Arden Syntax is one of the language with which we write MLM that is a component of CDSS. It was designated as a standard by HL7/ANSI. ArdenML is an XML version of Arden Syntax. In this paper we propose a tool which translates Arden Syntax MLMs into ArdenML MLM. To this end we first defines the corresponding relation between two languages. Next we presents a modified version of Arden Syntax grammar to improve performance of lexical analysis and minimize parsing conflicts. Finally we presents syntax and semantics gaps between the both languages, which are a structural representation problem, a data type problem, and a disrelation problem. Our translator resolves such issues and generates exact ArdenML codes for an arbitrary Arden Syntax MLM.

• Communications of Mathematical Education
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• v.20 no.4 s.28
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• pp.603-619
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• 2006

One of the most important aims in mathematics education is to enhance students' problem-solving abilities. To achieve this aim, in real school classrooms, many educators have examined and developed effective teaching methods, learning strategies, and practical problem-solving techniques. Among those trials, it is noticeable that Engel, Zeits, Shapiro and other not a few mathematicians emphasized 'Invariance Principle' as a mean of solving problems. This study is to consider the basic concept of 'Invariance Principle', analyze 'Invariance' concept in secondary Mathematics contents on the basis of framework of 'Invariance Principle' shown by Shapiro and discuss some instructional issues to occur in the process of it.