• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2003.11a
• /
• pp.69-73
• /
• 2003

In this paper, a synthesis method for the desired scattering pattern is presented when illuminating by TE-polarized and TM-polarized plane waves to arbitrary dielectric material. It is considered that the one-dimensional dielectric media are inhomogeneously distributed with continuously varying dielectric constants. Accordingly the desired patterns and the corresponding source distributions are inversely transformed by the proposed algorithm which are based on the one-dimensional inverse scattering problem. Some bandstop spatial filter are illustrated for applications.

• Proceedings of the KIEE Conference
• /
• 1996.07c
• /
• pp.1870-1872
• /
• 1996

This paper presents dielectric characteristics of $SF_6$ gas stressed by the non-oscillating and oscillating impulse voltages in inhomogeneous fields disturbed by metallic protrusion. The propose of this investigation is to present the predischarge development and dielectric characteristics of $SF_6$ gas under VFTOs. The experiments were carried out using a needle-to-plane and two needles-to-plane gap geometries in the gas pressure ranges from 0.1 to 0.5 MPa. The gap separation was 22 mm and the needle-shaped protrusions were made of stainless steel 10 mm in length and 1.0 mm in diameter. As a result, it was found that the breakdown mechanism and predischarge current are principally dependent on applied voltage waveform and polarity.

• Proceedings of the KIEE Conference
• /
• 1996.07c
• /
• pp.1747-1749
• /
• 1996

A method for calculating the electromagnetic scattering from arid internal field distribution of arbitrally, shaped, inhomogeneous dielectric bodies is presented. Tetrahedral volume elements are used to model a scattering body in which the electrical parameters are defined constant in each tetrahedron. Special basis functions are defined within the tetrahedral volume elements to satisfy the boundary condition at interfaces between different dielectric media. In order to test the accuracy of the solution by using the present method, it is applied to obtain the scattered field by the dielectric sphere. The accuracy of the fields calculated by using the tetrahedral cell method is found to be comparable to that of others.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.27 no.7
• /
• pp.867-876
• /
• 2003

The Lagrangian dispersion of fluid particles in inhomogeneous turbulence is investigated by a direct numerical simulation of turbulent channel flow. Four points Hermite interpolation in the homogeneous direction and Chebyshev polynomials in the inhomogeneous direction is adopted to simulate the fluid particle dispersion. An inhomogeneity of Lagrangian statistics in turbulent boundary layer is investigated by releasing many particles at several different wall-normal locations and tracking those particles. The fluid particle dispersions and Lagrangian structure functions of velocity are scaled by the Kolmogorov similarity. The auto-correlations of velocity and acceleration are shown at the different releasing locations. Effect of initial particle location on the dispersion is analyzed by the probability density function at the several downstreams and time instants.

• Journal of Korea Multimedia Society
• /
• v.18 no.7
• /
• pp.827-833
• /
• 2015

In this paper, we have compared three level set-based active contour (LSAC) methods on inhomogeneous MR image segmentation which is known as an important role of brain diseases to diagnosis and treatment in early. MR image is often occurred a problem with similar intensities and weak boundaries which have been causing many segmentation methods. However, LSAC method could be able to segment the targets such as the level set based on the local image fitting energy, the local binary fitting energy, and local Gaussian distribution fitting energy. Our implemented and tested the subcortical image segmentations were the corpus callosum and hippocampus and finally demonstrated their effectiveness. Consequently, the level set based on local Gaussian distribution fitting energy has obtained the best model to accurate and robust for the subcortical image segmentation.

• Journal of the Korean Mathematical Society
• /
• v.54 no.6
• /
• pp.1853-1878
• /
• 2017

Let $\{U(t,s)\}_{t{\geq}s}$ be a periodic evolutionary process with period ${\tau}$ > 0 on a Banach space X. Also, let L be the generator of the evolution semigroup associated with $\{U(t,s)\}_{t{\geq}s}$ on the phase space $P_{\tau}(X)$ of all ${\tau}$-periodic continuous X-valued functions. Some kind of variation-of-constants formula for the solution u of the equation $({\alpha}I-L)^nu=f$ will be given together with the conditions on $f{\in}P_{\tau}(X)$ for the existence of coefficients in the formula involving the monodromy operator $U(0,-{\tau})$. Also, examples of ODEs and PDEs are presented as its application.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.1004-1009
• /
• 2003

Electroosmotic flow induced by an applied electrostatic potential field in microchannel is analyzed in this study. The electroosmotic flow is an alternative to pressure driven flow in microchannels, but the usage has been limited to the simple cases. In this study, We analyze electroosmotic flow driven by inhomogeneous surface charge on the channel wall. The surface charge varies along a direction perpendicular to the electric field in order to generate the electroosmotic flow. A numerical results substantiate the highly efficient mixing performance. It is highly the beneficial to fabrication process since only straight microchannel rather than complex geometry is enough to yield efficient mixing.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.1085-1087
• /
• 2002

Deformation of soft tissue is known inhomogeneous and non-linear in general. In this study, we propose a measurement methodology of local/global strain during soft tissue elongation precisely using laser extensometer which has high accuracy, resolution and is possible to measure global/local strain. The mechanical tensile test are performed on tibialis cranialis, flexor hallucis longus, extensor digitorum longus of swine hindlimb. In order to measure target displacement, reflective marker is attached to detect elongation on specimen using surgical adhesive. The result of this study is to show that laser extensometer is valid to measure longitudinal elongation which is inhomogeneous and non-linear fur soft tissue.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.22 no.3
• /
• pp.84-90
• /
• 1985

A general procedure for finding the immittances of a general, uniformly coupled, n-line structure in an inhomogeneous medium is Presented. The expressions derived in terms of the normal modes of the system are in a convenient matrix form and can be used to compute or to derive the explicit expressions for the elements of the In-port immittance matrix. As an example, the closed form expressions for the elements of the admittance matrix of a sym-metrical four-line eight-port structure are given.

• Journal of the Optical Society of Korea
• /
• v.9 no.2
• /
• pp.74-78
• /
• 2005

With the fast Q-tensor method, which can model the defect dynamics in a liquid crystal director field, the nucleation and dynamical behavior of defects is modeled. In order to model the defect, hormeotropic aligned liquid crystal cell with step inhomogeneous electrode which has a height of $1\;{\mu}m$ is used. From the simulation, we can observe the nucleation and line of the defect from surface inhomogeneity and the experiment is performed for confirmation. The experimental result is compared with numerical modeling in order to verify the simulation of the defect nucleation.