• Advances in aircraft and spacecraft science
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• v.4 no.6
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• pp.711-727
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• 2017

This article is concerned with a two-dimensional problem of micropolar generalized thermoelasticity for a half-space whose surface is traction-free and the conductive temperature at the surface of the half-space is known. Theory of two-temperature generalized thermoelasticity with phase lags using the normal mode analysis is used to solve the present problem. The formulas of conductive and mechanical temperatures, displacement, micro-rotation, stresses and couple stresses are obtained. The considered quantities are illustrated graphically and their behaviors are discussed with suitable comparisons. The present results are compared with those obtained according to one temperature theory. It is concluded that both conductive heat wave and thermodynamical heat wave should be separated. The two-temperature theory describes the behavior of particles of elastic body more real than one-temperature theory.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.2 no.3
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• pp.26-31
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• 1991

The scattering property of TMz illuminated a elliptic dielectric cylinders with arbitrary cross section are analyzed by the boundary element techniques. The boundary element equations are for- mulated via Maxwell's equations, weighted residual of Green's theorem, and the boundary conditions. The unknown surface fields on the boundaries are then calculated by the boundary element integral equations. Once the surface fields are found, the scattered fields in far-zone and scattering widths (SW) are readily determined. To show the validity and usefulness of this formulation, computations are compared with those obtained using analytical method and one layer circular cylinder. As exten- sion to arbitrary cross-sectioned cylinders, plane wave scattering from a elliptic dielectric cylinders are numerically analyzed. A general computer program has been developed using the quadratic ele- ments(Higher order borndary elements) and the Gaussian quadrature.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06e
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• pp.247-250
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• 1998

The scattering of plane ultrasonic waves by the nuclear fuel pin of liquid metal reactor in sodium is studied. According to the internal composition in the cladding tube, the fuel pin has three cross sections, i.e. helium gas plenum, sodium-filled section, and fuel insertion section. The scattering spectra for each section of the fuel pin are different. The circumnavigating ultrasonic waves of each section are analyzed by the resonance scattering method. The whispering gallery wave modes are generated in the sodium-filled plenum section and the fuel rod insertion section with a sodium-gap. The circumferential wave modes are propagated in the cladding tube of the helium gas plenum section. The annular gap between the cladding tube and metal uranium pellet rod affects the scattering spectra. The different propagation characteristics can be utilized for the nondestructive method of detecting the unbonded area and measuring the level of the sodium-filled section of the fuel pin.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.882-885
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• 2002

Assessing the condition of air insulation by measuring electromagnetic wave generated in it by partial discharges gives warning of developing faults and breakdown which may give some bad effects to other thing concerned with it. Electromagnetic wave are taken from UHF antenna with 20k ~ 2GHz frequency range. The signal waveform and FFT(Fast Fourier Transform) results from UHF antenna for PD(partial discharge) generated from two different electrode(needle-plane, needle-needle) configurations are shown and it is processed by using PRPD($\Phi-q-n$ distribution) method. Cumulative pulse sequence during 100 period is compared with PRPD method. This also will show the possibility of making apparent distinction between two PD sources.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.1 no.1
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• pp.20-27
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• 1990

This paper presents an efficient method to estimate the induced current by the external electromagnetic wave when the line system is composed of cascaded transmission lines. To solve this phenomena, we apply the state variable method to the nonhomogeneous differential equation. This new method is the way of transferring the sources at a different point by the Ch- aracteristics of the transition matrix. Using this method, we investigate the characteristics of the induced power of the transmission line above the perfectly conducting ground plane.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.6
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• pp.1592-1601
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• 1998

The growing use of unlicensed wireless systems has spurred interest in the 2.4 Ghz ISM band. In order to facilitate the efficient design of such systems, understandings of the propserties of radio wave propagation in buildings is necessary. Many authors have reported about statistical propagation models based on the extensive measurements in buildings. However, measurement based statistical analysis will not be enough for the optimum deployment of the communication systems in the specific building. Aviding expensive measurements in the individual buildings prior to installation, or adjustments afterwards, theoretical prediction models have been developed to predict the path loss and delay spread from the building floor plane. Predictions shows good agreements with measurements except for a few environments which was surrounded by heavy scatterers.

• Journal of the Optical Society of Korea
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• v.6 no.3
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• pp.76-82
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• 2002

For dielectric gratings on a flat metal surface, photonic band gaps created by Brags scattering of surface plasmon polaritons are observed. The observation result that directly images this gap is compared with that predicted by a numerical model based on a plane wave expansion. Consistency between the experimental and numerical results is also confirmed by comparison with the well-known calculation method of diffraction, the rigorous coupled wave analysis method.

• Tunnel and Underground Space
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• v.6 no.3
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• pp.239-244
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• 1996

Cracks have influence on the physical and mechanical and, more importantly, on the engineering properties of the rock. Physical properties including the volumetric deformation coefficient, electrical resistivity, seismic wave velocity, and the mechanical properties such as the elastic constants and strength of rock are affected significantly by the presence of cracks of various sizes. An experimental program was undertaken to investigate the effect of a finite line crack on the diffraction of the plane compressional wave. Horizontal and vertical components of displacement and acceleration curve were obtained using a single-source and multi-receivers system. A theoretical model from numerical analysis implementing the finite element method was compared with the measured data.

• Structural Engineering and Mechanics
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• v.70 no.2
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• pp.143-152
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• 2019

In this study, stochastic responses of a cable-stayed bridge subjected to the spatially varying earthquake ground motion are investigated for variable local soil cases and wave velocities. Quincy Bay-view cable-stayed bridge built on the Mississippi River in Illinois, USA selected as a numerical example. The bridge is composed of two H-shaped concrete towers, double plane fan type cables and a composite concrete-steel girder deck. The spatial variability of the ground motion is considered with the coherency function, which is represented by the components of incoherence, wave-passage and site-response effects. The incoherence effect is investigated by considering Harichandran and Vanmarcke model, the site-response effect is outlined by using hard, medium and soft soil types, and the wave-passage effect is taken into account by using 1000, 600 and 200 m/s wave velocities for the hard, medium and soft soils, respectively. Mean of maximum response values obtained from the analyses are compared with those of the specific cases of the ground motion model. It is concluded that the obtained results from the bridge model increase as the differences between local soil conditions cases of the bridge supports change from firm to soft. Moreover, the variation of the wave velocity has important effects on the responses of the deck and towers as compared with those of the travelling constant wave velocity case. In addition, the variability of the ground motions should be considered in the analysis of long span cable-stayed bridges to obtain more accurate results in calculating the bridge responses.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.2
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• pp.196-209
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• 2010

For the analysis of Acoustic Target Strength(TS) that indicates the scattered acoustic intensity from the underwater vehicles, an analysis program that is applicable to scatterers insonified by spherical wave source in near field is developed. In this program, the Physical Optics(PO) method is embedded as a base component. To increase the accuracy of the program, multiple bounce effects based on Geometrical Optics(GO) method are applied. To implement multiple bounce effects, GO method is used together with PO method. In detail, GO method has a concern in the evaluation of the effective area, and PO method is involved in the calculation of Acoustic Target Strength for the final effective area that is evaluated by GO method. For the embodiment of near field spherical wave source originated multiple bounce effects, image source concept is implemented additively to the existing multiple bounce algorithm which assumes plane wave insonification. Various types of models are tested to evaluate the reliability of the developed program and finally, a submarine is analyzed as an arbitrary scatterer.