• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.552-554
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• 1999

Phonon scattering and impact ionization models have been presented to analyze hot carrier transport in high energy region, using full band model and Fermi's golden rule. We have investigated temperature dependent properties for impact ionization process of Si using realistic energy band structures at 77K and look. The realistic full band model, obtained from the empirical pseudopotential method with local from factors, is used to calculate scattering rate. The accurate calculation of impact ionization rate requires the use of a wavevector- and frequency-dependent dielectric function ξ ( q,$\omega$). The empirical phonon scattering rate P$\sub$ph/, is given by deriving from linear function for P$\sub$ph/ versus D(E) since the phonon scattering rate is linearly depended on density of states D(E). Impact ionization rate p,, is calculated from the first principle's theory. and fitted by modified Keldysh formula having power of above 2.

• Journal of the Korean Society of Radiology
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• v.16 no.4
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• pp.395-403
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• 2022

Flat-panel detector (FPD) used in digital radiographic imaging systems was used to perform a quantitative power spectrum evaluation as a result of the thickness change of polymethyl methacrylate (PMMA), a tissue equivalent. As the PMMA thickness increases with the resolution-chart phantom image, the effect of the scattering line increases, indicating that the modulation characteristics decrease, and the image is bright. The results show that the noise of the image increases, and noise-power spectral images are obtained by Fourier transform to confirm by spatial frequency. Thus, it can be verified that the PMMA thickness and noise are proportional through the result of evaluating the change of resolution characteristics and representing the 2D noise-power spectrum as one-dimensional values by evaluating the change of scattering line with MTF as the PMMA thickness increases in the image.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.379-387
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• 2002

In this paper, we present a procedure to obtain the transient scattering response from three-dimensional arbitrarily shaped and closed conducting bodies using time-domain magnetic field integral equation (TD-MFIE) with triangular patch functions. This approach results in accurate and comparably stable transient responses from conducting scatterers. Detailed mathematical steps are included, and several numerical results are presented and compared with results from a time-domain electric field integral equation (TD-EFIE) and the inverse courier transform solution of the frequency domain results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.10
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• pp.811-816
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• 2018

When applying the MLFMM algorithm to a large scattering problem, the accuracy of the calculation of the transfer function has a crucial effect on the final simulation results. The numerical accuracy for the double integral on the unit sphere is strongly dependent on the sampling number. With an increasing the sampling points, the overall required memory and running time of the MLFMM simulation also increases. Hence, an optimal over-sampling rate for the number of the sampling points is numerically obtained, which is verified for a real large scattering problem.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.3
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• pp.68-74
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• 1995

In this paper, E-polarized electromagnetic scattering by a conducting strip grating with 2 dielectric layers is analyzed to calculate the geometrical reflected and transmitted power by applying the Fourier-Galerkin moment mothed. The induced current density is expanded in a Fourier series using a simple exponential func- tion, and we applied the boundary conditions to the electromagnetic fields at the boundary planes. The sca- ttered electromagnetic fields are expanded in a series of Floquet mode functions. To examine the accuracy of the present method, the geometrically reflected and transmitted power are evaluated and compared with those of the existing papers, and then the numerical results are found in good agreement with those of the existing paper.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.175-178
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• 2005

TM plane-wave scattering from finite rectangular grooves in a conducting plane is systematically analyzed with the overlapping T-block method. Multiple rectangular grooves are divided into several overlapping T-blocks to obtain the fast CPU time, CAD applicability, and wide versatility. The scattered fields are obtained in simple closed forms including a fast-convergent integral.

• Journal of the Korean Vacuum Society
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• v.8 no.1
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• pp.55-62
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• 1999

Monte Carlo ion scattering program is improved with the single scattering methods where the total cross section and the mean free path are calculated as a function of atomic density during ion scattering in matter. The relations among the parameters of incident ions and substrate materials are investigated to the sputtering phenomena. The sputtering yield has been analyzed with the dependence on the incident ion species and energy, incident angle, and surface binding energy. The energy distribution of sputtered particles is discussed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.4
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• pp.895-899
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• 2000

A method of measuring Q of a two port cavity by scattering parameters is proposed. The scattering parameters of a two port cavity resonator are derived by a lumped equivalent circuit model as a function of cavity parameters, including the cavity Q. These can be also obtained by direct measurement with a modern network analyzer, The results show good agreement with those from other well-known methods. This two port measurement can provide additional information such as the coupled power ratio, which is one of the important parameters for the beam accelerating cavities.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.2
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• pp.102-109
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• 2000

This paper describes two different theories used to model the scattering of ultrasound by a volumetric flaw and a crack-like flaw. The elastodynamic Kirchhoff approximation (EKA) and the geometrical theory of diffraction (GTD) are applied respectively to a cylindrical cavity and a semi-infinite crack. These methods are known as high frequency approximations. The 2-D elastodynamic scattering problems of a plane wave incident on these model defects are considered and the scattered fields are expressed in terms of the reflection and diffraction coefficients. The ratio of the scattered far field amplitude to the incident wave amplitude is computed as a function of the angular location and compared with the boundary element solutions.

• Proceedings of the Korea Contents Association Conference
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• 2003.11a
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• pp.249-252
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• 2003

Scattering solutions of an H-plane T-junction in a parallel-plate waveguide are theoretically investigated. The iterative procedure and Green's function relation are used to obtain the iterative equations for the $E_{z}$ field modal coefficients, thus resulting in matrix solutions. The scattering characteristics of reflection and transmission powers are presented and compared with other existing results.s.