• Journal of the Chungcheong Mathematical Society
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• v.7 no.1
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• pp.123-139
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• 1994

In this paper we are concerned with optimal control problems whose costs are quadratic and whose states are governed by linear delay differential equations and general boundary conditions. The basic new idea of this paper is to introduce a new class of linear operators in such a way that the state equation subject to a starting function can be viewed as an inhomogeneous boundary value problem in the new linear operator equation. In this way we avoid the usual semigroup theory treatment to the problem and use only linear operator theory.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.368-368
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• 2009

• Journal of the Korean Ceramic Society
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• v.27 no.8
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• pp.1020-1026
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• 1990

The effect of heating rate on the microstructural evolution during sintering of PZT ceramics has been investigated. In case of PZT powder compacts containing excess of PbO, fast heating caused incomplete rearrangement of solid grains in a liquid, resulting in lower density and inhomogeneous pore shape ; on contrary, slow heating resulted in better densification. In contrast, in case of compacts without excess PbO, the densification was enhanced by fast heating due to suppression of the grain growth.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.14 no.1_2
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• pp.143-145
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• 1992

Fourteen masses in the maxillofacial areas which are not diagnosised simply as abscess were studied with ultrasound to evaluate its diagnostic role. Benign mass showed homogeneous echopattern with smooth margin and cyst a few internal echo with smooth margin. But malignant mass showed irregular margin, inhomogeneous echotexture and deep extension. Ultrasonography considered as an initial noninvasive imaging modality for the evaluation of maxillofacial masses.

• Geomechanics and Engineering
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• v.7 no.1
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• pp.1-36
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• 2014

The effect of various parameters on the propagation of surface waves in electro-magneto thermoelastic orthotropic granular non-homogeneous medium subjected to gravity and initial compression has been studied. All material coefficients are obeyed the same exponent-law dependence on the depth of the granular elastic half space. Some special cases investigated by earlier researchers have also been deduced. Dispersion curves are computed numerically and presented graphically.

• Honam Mathematical Journal
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• v.24 no.1
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• pp.35-41
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• 2002

The solutions of a homogeneous system in state space form $\dot{x}=Ax$ are to the form $x=e^{At}x_0$ and the solutions of an inhomogeneous system $\dot{x}=Ax(t)+f(t)$ are to the form $x=e^{At}x_0+{{\int}_0^t}\;e^{A(t-{\tau})}f({\tau})d{\tau}$. In this note we show that the solution of descriptor systems under some conditions exists, and is unique, moreover it is interesting to know the solutions of descriptor system are schematically like the solutions as in the state space form. Also we will give some algorithms to compute these solutions.

• Bulletin of the Korean Mathematical Society
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• v.53 no.2
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• pp.615-640
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• 2016

We consider the fourth-order $Schr{\ddot{o}}dinger$ equation with focusing inhomogeneous nonlinearity ($-{\mid}x{\mid}^{-2}{\mid}u{\mid}^{\frac{4}{n}}u$) in high space dimensions. Extending Glassey's virial argument, we show the finite time blowup of solutions when the energy is negative.

• Bulletin of the Korean Chemical Society
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• v.20 no.11
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• pp.1340-1344
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• 1999

The electrochemical behavior of oxide layers on aluminium was studied using electrochemical impedance spectroscopy. Impedance spectra were taken at a compact and a porous oxide layer of Al. The anodic films on Al have a variable stoichiometry with gradual reduction of oxygen deficiency towards the oxide-electrolyte interface. Thus, the interpretation of impedance spectra for oxide layers is complicated, with the impedance of surface layers differing from those of ideal capacitors. This layer behavior with conductance gradients was caused by an inhomogeneous dielectric. The frequency response cannot be described by a single RC element. The oxide layers of Al are properly described by the Young model of dielectric constant with a vertical decay of conductivity.

• Bulletin of the Society of Naval Architects of Korea
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• v.24 no.2
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• pp.55-61
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• 1987

The wave system due to a moving submerged body is investigated both theoretically and numerically. Boussinesq equation, which is derived under the assumption that the effects of nonlinearity and wave dispersion are of the same order, is generalized to take the forcing agency into account. Furthermore, under the more restrive assumption that the disturbance is of higher order, inhomogeneous Korteweg-de Vries equation is derived. These equations are solved numerically to obtain the generated wave system and the wave-making resistance. These results are compared with those given by the linear theory.

• Journal of Magnetics
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• v.5 no.1
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• pp.9-12
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• 2000

Electron spin resonance and magnetization measurements were carried out on $La_0.7Ca_0.3MnO_3$ in the ferromagnetic as well as paramagnetic phases. Evidence of an inhomogeneous magnetic structure, consisting of ferro-magnetic microregions embedded in an antiferromagnetic matrix near $T_c$, as well as similar local magnetic structures above and below $T_c$, were found.