• The Journal of Information Systems
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• v.6 no.2
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• pp.147-163
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• 1997

The usages of the relational database systems have been increased nowadays. However there is a constraint that the standard query language for a database system requests users to know the exact condition for a query. In this paper a FSQL(Fuzzy SQL) systems is proposed and implemented for the imprecise queries which do not include the exact condition. Moreover this system can supply the obvious results for the queries effectively. We define a simple fuzzy query language and use a method using the metadatabase to implement the FSQL system. This FSQL system can be combined with a relational database system without any painful effort.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.108.5-108
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• 2001

The research of friction compensation control system seeks the accuracy, the velocity increase of the table, and the settling time reduction. The friction is the disturbance which has the greatest influence, but the past research of control system doesn´t perform exact modeling of the friction. So this research aims at the friction compensation control system, the exact modeling of the friction, comparison between the model simulation and experimental data, and the design of observer for the friction estimation.

• Honam Mathematical Journal
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• v.30 no.4
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• pp.631-635
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• 2008

In this paper we discuss on the formal linearization and exact solution of Klein-Gordon's equation (1) $u_{tt}-au_{xx}+bu-cu^3=0 a,b,c{\in}R^+$ So that we know an efficient method for constructing of particular solutions of some nonlinear partial differential equations is introduced.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.609-612
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• 1997

This paper deals with in-plane vibration analysis of curved beams. The exact dynamic element method is applied to obtain the dynamic model for curved beams. Numerical examples are provided to validate the proposed modeling and analysis method. The numerical results show that the proposed method is useful for the dynamic analysis of curved beams.

• International Journal of Internet, Broadcasting and Communication
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• v.6 no.2
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• pp.1-9
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• 2014

This paper presents a study on nonlinear time varying systems based on differential geometry. A brief introduction about controllability and involutivity will be presented. As an example, the exact feedback linearization and the approximate feedback linearization are used in order to show some application examples.

• Journal of the Chungcheong Mathematical Society
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• v.28 no.4
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• pp.583-590
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• 2015

This paper deals with linear impulsive fractional differential equations involving the Caputo derivative with non-integer order q. We provide exact solutions of linear impulsive fractional differential equations with constant coefficient by mean of the Mittag-Leffler functions. Then we apply the exact solutions to improve impulsive integral inequalities with singularity.

• Journal of the Korean Operations Research and Management Science Society
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• v.4 no.1
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• pp.53-58
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• 1979

Production lot sizing problem for a system with exponentially decaying inventory is considered. From the exact cost function developed under conditions of constant demand and no shortages permitted, an approximate optimal solution is derived. The formula is compared with those of the exact solution obtained from numerical procedure and other existing approximate solution. Finally some notable properties of the formula are investigated and shown to be consistent.

• Journal of the Korean Mathematical Society
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• v.37 no.4
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• pp.593-611
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• 2000

For linear time-varying control systems with constrained control described by both differential and discrete-time equations in Banach spaces was give necessary and sufficient conditions for exact global null-controllability. We then show that for such systems, complete stabilizability implies exact null-controllability.

• Journal of the Korean Mathematical Society
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• v.43 no.1
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• pp.199-213
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• 2006

We compute the holomorphic derivative of the harmonic measure associated to a $C^\infty$bounded domain in the plane and show that the exact Bergman kernel function associated to a $C^\infty$ bounded domain in the plane relates the derivatives of the Ahlfors map and the Szego kernel in an explicit way. We find several formulas for the exact Bergman kernel and the Szego kernel and the harmonic measure. Finally we survey some other properties of the holomorphic derivative of the harmonic measure.

• Journal of the Korean Mathematical Society
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• v.54 no.5
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• pp.1623-1639
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• 2017

The generalized coGottlieb sets are not known to be groups in general. We study some conditions which make them groups. Moreover, there are actions on the generalized coGottlieb sets which are different from known actions up to now. We give related exact sequence of the generalized coGottlieb sets. Using them, we obtain certain results related to the maps which preserve generalized coGottlieb sets.