• Journal of the Korean Mathematical Society
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• v.33 no.4
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• pp.1039-1046
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• 1996

In the theory of partial differential equations with given initial values and boundary values one usually investigates to examine the well-posedness, that is, the unique existence of the solution as well as its continuous dependence on the data. This theory is strong enough for us to determine the situation anywhere and anytime provided that the initial data are actually given. However, in many cases the data are not completely known for us. Then in those situations arise the new problem to determine the unknown initial data by taking other conditions for the solutions.

• Bulletin of the Korean Mathematical Society
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• v.51 no.1
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• pp.13-27
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• 2014

The purpose of this paper is to derive a perturbation theory of evolution systems of the hyperbolic second order hyperbolic equations. We give an example of a partial functional equation as an application of the preceding result in case of the mixed problems for hyperbolic equations of second order with unbounded principal operators.

• International Journal of Control, Automation, and Systems
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• v.5 no.1
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• pp.93-98
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• 2007

A class of new observers in descriptor linear systems, proportional-derivative(PD) observers, are proposed. A parametric design approach for such observers is proposed based on a complete parametric solution to the generalized Sylvester matrix equation. The approach provides complete parameterizations for all the observer gains, gives the parametric expression for the corresponding left eigenvector matrix of the observer system matrix, realizes elimination of impulsive behaviors, and guarantees the regularity of the observer system.

• Journal of the Korean Mathematical Society
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• v.48 no.3
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• pp.585-597
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• 2011

We prove the existence and uniqueness of classical solutions for a quasilinear delay integrodifferential equation in Banach spaces. The result is established by using the semigroup theory and the Banach fixed point theorem.

• Journal of the Korean housing association
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• v.11 no.3
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• pp.9-18
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• 2000

The fuzzy theory is on the basis of understanding of the subjectivity and the ambiguity. The paradigm of the fuzzy theory is to explore a regularity from the subjectivity and the ambiguity. Nowadays, the fuzziness, the main concept of the fuzzy theory, is widely applied to a lot of fields as the theory which is positively accepted and actively interpreted. In the science, the fuzziness is officially called as multi-valence. On the other side, there exists the other theory called Han-ism which is presumed as a prototype of korean philosophy. The basic concept of the Han-ism - one, many, middle, same, about - includes the fuzziness. The purpose of this study is to unfold the interrelationship between the fuzzy theory and Han-ism, and furthermore, to interpretate the cultural phenomenon and architectural spaces in koreas traditional architecture with a viewpoint, the fuzziness of the Han-ism.

• Journal of applied mathematics & informatics
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• v.17 no.1_2_3
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• pp.623-631
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• 2005

The approximate controllability for the nonlinear control system with nonlinear monotone hemicontinuous and coercive operator is studied. The existence, uniqueness and a variation of solutions of the system are also given.

• Communications of the Korean Mathematical Society
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• v.12 no.4
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• pp.1039-1064
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• 1997

Existence and Uniqueness for Volterra equations (VE) with a weak regularity assumption on A, the relative closedness of A are investigaed by means of the Laplace transform theory. Also, (VE) are studied by means of the method of convoluted solution operator families.

• Journal of applied mathematics & informatics
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• v.7 no.3
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• pp.969-982
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• 2000

The approximate controllability for the nonlinear control system with nonlinear monotone hemicontinuous and coercive operator is studied. The existence, uniqueness and a variation of solutions of the system are also given.

• Journal of the Korean Mathematical Society
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• v.34 no.1
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• pp.13-21
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• 1997

In recent years M. Hochster and C. Huneke introduced the notions of tight closure of an ideal and of the weak F-regularity of a ring of positive prime characteristic. Here 'F' stands for Frobenius. This notion enabled us to play an important role in a commutative ring theory, and other related topics.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.05
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• pp.281-284
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• 1995

This paper describes a complexity measure algorithm based on nonlinear dynamics(chaos theory). In order to quantify complexity or regularity of biomedical signal, this paper proposed fractal dimension-1 and fractal dimension-2 algorithm with digital filter. Approximate entropy algorithm which measure a system regularity are also compared. In this paper investigate what we quantify of biomedical signal. These quantified complexity measure may be a useful information about human physiology.