• Journal of applied mathematics & informatics
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• v.26 no.1_2
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• pp.299-306
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• 2008

Finite difference schemes are considered for a $Ca^{2+}$ diffusion equations, which discribe $Ca^{2+}$ buffering by using stationary and mobile buffers. Stability and $L^\infty$ error estimates of approximate solutions for the corresponding schemes are obtained using the extended Lax-Richtmyer equivalence theorem.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04b
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• pp.289-291
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• 2002

Host of source separation methods focus on stationary sources so higher-order statistics is necessary In this paler we consider a problem of source separation when sources are second-order nonstationary stochastic processes . We employ the natural gradient method and develop learning algorithms for both 1inear feedback and feedforward neural networks. Thus our algorithms possess equivariant property Local stabi1iffy analysis shows that separating solutions are always locally stable stationary points of the proposed algorithms, regardless of probability distributions of

• Journal of the Chungcheong Mathematical Society
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• v.35 no.4
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• pp.307-313
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• 2022

In this paper, we will consider the periodic stationary Stokes equations on Rⁿ. For the cube of the period, we set Ω = ∏ⁿ_i=1(0, L_i). And we will study the stability of the solutions on various functional spaces, for the Stokes equations on Rⁿ.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2623-2628
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• 2013

Three di-acyl chlolide reagents, adipoyl chloride, terephthaloyl chloride and isophthaloyl chloride, were used as spacer reagents to prepare bonded type of three cellulose (3,5-dimethylphenyl)carbamate (CDMPC) chiral stationary phases (CSPs). The CDMPC CSPs were prepared using these three acid chlorides as spacer agents at the 6-position of the primary hydroxyl group on the glucose unit of cellulose regioselectively. The chiral recognition ability of the prepared CSPs for five racemates was evaluated by normal-phase high-performance liquid chromatography (HPLC) with the following mobile phases: hexane/isopropanol (IPA), hexane/IPA/tetrahydrofuran (THF) and hexane/IPA/chloroform. The result showed that these prepared CSPs can be used in THF and chloroform solutions and the chiral recognition abilities of the CSPs were improved depending on the eluents and chiral samples.

• Journal of the Korean Mathematical Society
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• v.38 no.1
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• pp.1-23
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• 2001

This paper is concerned with an optimal shape control problem for the stationary Navier-Stokes system. A two-dimensional channel flow of an incompressible, viscous fluid is examined to determine the shape of a bump on a part of the boundary that minimizes the viscous drag. by introducing an artificial compressibility term to relax the incompressibility constraints, we take the penalty method. The existence of optima solutions for the penalized problem will be shown. Next, by employing Lagrange multipliers method and the material derivatives, we derive the shape gradient for the minimization problem of the shape functional which represents the viscous drag.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.6
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• pp.1294-1301
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• 2005

In this paper, we investigate the problems of existing solutions for intrusion detection and propose an agent network based on stationary and mobile agents on agent system to solve them. The proposed agent network can detect intrusions, collect their information and execute active responses against intruders by introducing various stationary and mobile agents. It will show a new approach of active responses against more intelligent and distributed intrusions.

• Structural Engineering and Mechanics
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• v.44 no.4
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• pp.487-499
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• 2012

Dynamic instability of beams subjected to periodic axial forces is studied using the discrete singular convolution (DSC) method with the regularized Shannon's delta kernel. The principal regions of dynamic instability under different boundary conditions are examined in detail, and the non-stationary vibrations near the stability-instability critical regions have been investigated. It is found that the results obtained by using the DSC method are consistent with the analytical solutions, which shows that the DSC algorithm is suitable for the problems considered in this study. It was found that there is a narrow region of beat vibration existed in the vicinity of one side (${\theta}/{\Omega}$ > 1) of the boundaries of the instable region for each condition.

• Bulletin of the Korean Chemical Society
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• v.17 no.4
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• pp.385-390
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• 1996

It has been well known that the Grad thirteen-moment equations have solutions only when the Mach number is less than a limiting value for the stationary plane shock-waves. The limit of Mach number has been re-examined by including successive terms in the series expansion of distribution function. The method employed is the linear analysis of moment equations near up-streaming and down-streaming flows. For the thirteen moment case, it has been confirmed that equations have solutions only when the Mach number is less than 1.6503, which is consistent with the literature value. For the case of twenty moments, the limit of Mach number is decreased to 1.3416.

• Journal of the Korean Mathematical Society
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• v.58 no.5
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• pp.1279-1298
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• 2021

The aim of this paper is to prove the existence of the global attractor of the Cauchy problem for a semilinear degenerate hyperbolic equation involving strongly degenerate elliptic differential operators. The attractor is characterized as the unstable manifold of the set of stationary points, due to the existence of a Lyapunov functional.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.141-146
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• 2013

This research investigates the stability analysis for the rotating and the stationary grooved journal bearing. The dynamic coefficients of the journal bearing are calculated by using FEM and the perturbation method. When journal bearing is in whirling motion, the dynamic coefficients have time-varying components as a sine wave due to the reaction force of oil film toward the center of journal even in the steady state. The solutions for the equations of motion can be assumed as the Fourier series expansion. The equations of motion can be rewritten as the linear algebraic equations with respect to the Fourier coefficients. Then, stability of the grooved journal bearing can be calculated by Hill's infinite determinant. The periodic function of dynamic coefficients is derived using Fourier Fast Transform(FFT).The stability of journal bearing is determined as rotating speed increases and the stability of rotating grooved journal bearing is compared and discussed with the stability of stationary grooved journal bearing.