• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.04a
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• pp.106-112
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• 1998

A numerical experiment is conduced to study the wave screening effectiveness of wave barriers which are constructed to reduce the ground-transmitted vibration. The finite element method is used for the simulation of the wave propagation behavior. In order to reduce the computational burden the absorbing boundary's one employed. Validity of the numerical model is checked by comparing the results with the published data. The screening effectiveness of the in filled trenches is then studied for different trench dimensions and material properties.

• Journal of Astronomy and Space Sciences
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• v.9 no.1
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• pp.69-88
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• 1992

The effects of the ionosphere on the radio wave propagation are scattering of radio waves, attenuation, angle error, ranging error, and time delay. If ionospheric conditions are suitable, the charged particles can remove energy from radio waves and thus attenuate the signal. Also, a radio wave traveling a path along which the electron density is not constant undergoes changes in direction, positon and time of propagation. The present study is based on Korean ionospheric data obtained at the AnYang Radio Research Institute from Jan. 1985 through Oct. 1989. The data are used to simulate the Korean ionosphere following the Chapman law. The effects of the model ionosphere on the radio wave propagation, such as the angle, position error, time delay, and the attenuation, are studied for the various cases of the wave frequency and the altitude.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.4
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• pp.594-606
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• 1999

The electromagnetic scattering characteristics by a periodic strip grating on a grounded dielectric slab for TE polarization case is examined from the viewpoints of both the reflection grating and the leaky wave antenna problems. Numerical results for two kinds of Bragg blazing (resonance type and non-resonance type) phenomena are given and some discussions on the properties such as complex propagation constants, scattering characteristics, and distributions of strip current density are presented.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.143-146
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• 2004

Signals of the short wave part of centimetre, millimetre and optic wave length ranges are being broadly used in the communication, location and remote sensing systems with space channels. In this case the presence of discrete non-uniform mediums like orbital debris, space dust and other discrete formations in the propagation channel may have substantial influence upon the characteristics of wave processes. and thus upon the data system quality. Mathematical models for studying the discrete non-uniform mediums effect on the characteristics of electromagnetic wave propagation are analyzed in this paper.

• Journal of the Korean Applied Science and Technology
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• v.23 no.1
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• pp.70-76
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• 2006

The influence of fluorophor, scatterer, absorber in turbid materials by light scattering were interpreted for the scattered fluorescence intensity and wavelength, it is studied the molecular property by laser induced fluorescence spectroscopy. It can be found that the effects of optical property are penentrated in scattering media by the optical $parameters({\mu}s$, ${\mu}a$, ${\mu}t$, ${\gamma}$, ${\rho})$. The value of scattering coefficient ${\mu}s$ is large appeared by means of the increasing particles of scattering, it can be found that the slope appears exponentially as a function of distance from laser source to detector. It may also utilize in designing the best model for oil chemistry, laser medicine and application of medical engineering.

• Journal of electromagnetic engineering and science
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• v.10 no.2
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• pp.61-66
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• 2010

This paper is concerned with an analysis of the back scattering of electromagnetic waves from a target moving along random rough surfaces such as the desert, and sea. First, the discrete ray tracing method(DRTM) is introduced, and then, this method is applied to the back scattering problem in order to investigate the effect of the back scattering from random rough surfaces on the electric field intensities. Finally, numerical examples of various height deviations of the Gaussian type of rough surfaces are shown. It is numerically demonstrated that the back scattering is dominated by the diffractions related to the reflections from the random rough surfaces.

• Journal of the Korean Applied Science and Technology
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• v.28 no.1
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• pp.102-108
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• 2011

The study of wave propagation and scattering in biological media has become increasingly important in recent years. The propagation of light within tissues is an important problem that confronts the dosimetry of therapeutic laser delivery and the development of diagnostic spectroscopy. In the clinical application of photodynamic therapy(PDT) and in photobiology, the photon deposition within a tissue determines the spatial distribution of photochemical reactions. Scattered light is measured as a function of the distance (r) between the axis of the incident beam and the detection spot. Consequently, knowledge of the photosensitizer(Chlorophyll-a) function that characterizes a phantom is measured. To obtain the results of scattering coefficients(${\mu}s$) of a turbid material from diffusion described by experimental approach. It was measured the energy fluency of photon radiation at the position of penetration depth. From fluorescence experimental method obtained the analytical expression for the scattered light as the values of $(I/I_o)_{wavelength}$ vs the distance between the center of the incident beam and optical fiber in terms of the condition of "in situ spectroscopy(optically thick)" and real time by fluorometric measurements. The result was compromised with transport of intensities though a random distribution of scatters.

• Structural Engineering and Mechanics
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• v.66 no.4
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• pp.495-504
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• 2018

The current study is dedicated to study the thermal effects of wave propagation in beams, reinforced by carbon nanotubes (CNT). Beams, made up of carbon nanotube reinforced composite (CNTRC) are the future materials in various high tech industries. Herein a Winkler elastic foundation is assumed in order to make the model more realistic. Mostly, CNTs are pervaded in cross section of beam, in various models. So, it is tried to use four of the most profitable reconstructions. The homogenization of elastic and thermal properties such as density, Yong's module, Poisson's ratio and shear module of CNTRC beam, had been done by the demotic rule of mixture to homogenize, which gives appropriate traits in such settlements. To make this investigation, a perfect one, various shear deformation theories had been utilized to show the applicability of this theories, in contrast to their theoretical face. The reigning equation had been derived by extended Hamilton principle and the culminant equation solved analytically by scattering relations for propagation of wave in solid bodies. Results had been verified by preceding studies. It is anticipated that current results can be applicable in future studies.

• The Journal of the Acoustical Society of Korea
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• v.11 no.4
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• pp.22-30
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• 1992

The propagation of coherent time-harmonic elastic SH waves in a medium with random distribution of cylindrical inclusions is studied for characterizing the dynamic elastic modulus and the attenuation property of fiber-reinforced composite materials. A multiple scattering theory using the single scattering coefficients in conjunction with the Lax's quasicrystalline approximation is derived and from which the dispersion relation for such medium is obtained. The pair-correlation functions between the cylinders which are needed to formulate the multiple scattering interaction between the cylinders are obtained by Monte Carlo simulation method.From the numerically calculated complex wavenumbers, the propagation speed of the average wave, the coherent attenuation coefficient and the effective shear modulus are presented as functions of frequency and area density.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.231-236
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• 2017

The space harmonics generated by a plane-wave incident upon a multi-layered dielectric grating can undergo strong resonance scattering variations known as GMR(guided-mode resonance). To clarify these effects, we examine the field propagation and dispersion curve inside the grating region by using a rigorous equivalent transmission-line theory(RETT). The results show that, at the peak of a scattering resonance, the reflected mode is almost identical to a leaky wave that can be supported by the grating structure. Thus, we confirm and generalize previous research that has occurred GMR effect associated with the free-resonant character of leaky waves at multi-layered dielectric gratings. Quantitative simulation results illustrating the behavior of typical gratings are given, and the special case of normal incidence is discussed for TM mode.