• Kyungpook Mathematical Journal
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• v.56 no.4
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• pp.1247-1257
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• 2016

In this paper, we discuss the crossing change operation along exchangeable double curves of a surface-knot diagram. We show that under certain condition, a finite sequence of Roseman moves preserves the property of those exchangeable double curves. As an application for this result, we also define a numerical invariant for a set of surface-knots called du-exchangeable set.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.97-101
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• 2003

In this paper, we propose a new diagnosis method of DC/UC converter aging. The method is based on parasitic resister change with aging process. we apply to on-line diagnosis of DC/DC converter because of observing not a device but a system. We present the mathematical analysis and experimental study.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.26-32
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• 2008

Middle Route Project, the largest water conveyance system in China delivers the water of Changjiang River to North China. In order to create canal operation simulation system, mathematical models are established based on the analysis of hydraulics about steady flow, unsteady flow, and check gate. By simulating the canal operation behavior, we improved the check gate control algorithm and predicted the change process of water surface and flow profile which is very valuable to actual canal operation.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.214-218
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• 1988

This paper suggests mathemathical engine model which can simulate generalized gasoline engine. Suggested engine model contains air/fuel inlet element, intake manifold, combustion, engine dynamics. In order to analyze a gasoline engine, physical characteristics of engine and steady state engine data should be controlled. In adaptation for abrupt change of circumstance or drive conditions, this model can analyze important physical phenomena in the intake manifold by computer simulation. This model can also evaluate statuses of drive under various working conditions precisely. Therfore, this model suggests basic datum to evaluate the engine system which are needed in designing and development of engine controller.

• Korean Journal of Mathematics
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• v.16 no.4
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• pp.471-480
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• 2008

As students with low basic knowledge of mathematics increase, they have had difficulties in studying statistics theory class. By using recent students' characteristics which prefer seeing directly and checking to thinking logically, we try to change the teaching method into teaching in the computer lab(SAS program). We investigate whether changing the teaching method has effects on students' achievements and interests or not. The purpose of this study is to grope for a better teaching and develop mathematics education's satisfaction and qualification.

• KSBB Journal
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• v.5 no.4
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• pp.377-382
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• 1990

The characteristics controlled drug release have been studied for biodegradable polymer matrix. Polymer matrix was prepared from glycerine, prednisolone and dextran. Mathematical analysis of the data showed that the release behavior actually conformed to the Higuchi's diffusion controlled model. The release time was increased as drug loading doses increased, whereas decreased as glycerine concentration increased. The release rate did not change by varying molecular weight of dextran.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1479-1482
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• 2002

In this work, a recursive parameter estimation algorithm estimates the mathematical model of steam generators every time step and a receding horizon controller is designed by using this estimated linear steam generator model of which parameters change as time goes on. It was shown through application to a linear model of steam generator that the proposed controller has good performance.

• The Pure and Applied Mathematics
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• v.14 no.2 s.36
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• pp.99-109
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• 2007

Being complicated in computation, iteration of a nonlinear 1-dimensional mapping makes many interesting problems, one of which is about the change of the number of vertices under iteration. In this paper we investigate iteration of polygonal functions which each have only one vertex and give conditions under which the number of vertices either does not increase or has a bound under iteration.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.7
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• pp.957-965
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• 2012

Korean government has been preparing the introduction of Emission Trading as part of the framework convention on Climate Change as a relief of negative downstream effect over electricity industry. This paper develops a mathematical model amenable to analyzing the economic impact of introduced emission trading system on the national generation expansion planning. The developed model was also employed with a case study to verify its applicability.

• The Pure and Applied Mathematics
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• v.10 no.2
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• pp.71-102
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• 2003

The purpose of this paper is to study the geometry of null curves in a 6-dimensional semi-Riemannian manifold $M_q$ of index q, since the general n-dimensional cases are too complicated. We show that it is possible to construct three types of Frenet equations of null curves in $M_q$, supported by one example. We find each types of Frenet equations invariant under any causal change. And we discuss some properties of null curves in $M_q$.