• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.3
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• pp.471-481
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• 1995

Measurement factors for the dielectric properties of low dielectric loss materials (tan${\dalta}{\le}10^{-4}$) were investigated using the dielectric rod resonator method. It was shown that the relative conductivity (${\sigma}_{r}$) should be controlled within a 5% to obtain the standard deviations of less than 0.07 for permittivity .epsilon.r and 0.06${\times}10^{-4}$ for tan.delta.respectively. Surface resistivity (R$_s$) could be reduced when the surface roughness of parallelled conducting plate was less than 0.07 .mu.m. Measurement error for the permittivity was $\pm$0.02% independent of probe loop size, whereas the error in Q value was reduced with the decrease in probe loop size and also with the increase in the absolute values of Q. Reliable Q values were determined with the probe loop size of less than 4mm. The accurate for the distance between the measuring probe loop and the sample could be obtained when the insertion loss of resonant frequency ranged -15dB - -30dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.6
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• pp.996-1005
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• 2000

This paper proposed a novel broadband ceramic dielectric antenna by improving the conventional broadband technique that very high permittivity material is attaching to one side of low permittivity material. The broadband ceramic dielectric antenna can be designed by using our proposed method, and it overcomes the disadvantage of narrow bandwidth problem. For the proposed ceramic dielectric antenna, a 10 dB return-loss bandwidth of 33.9% has been achieved. The measurement and numerical results(Finite Element Method) are performed and confirmed to a good agreement with each other. The proposed ceramic dielectric antenna is designed and implemented to extend enough the coverage of dual band (PCS+IMT-2000).

• Journal of the Korean Chemical Society
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• v.45 no.3
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• pp.201-207
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• 2001

The dielectric relaxation study for aniline-dimethylsulphoxide (DMSO) and aniline-dim.ethylformamide(DMF) has been carried out using the Time domain reflectometry (TDR) technique, at different temperature and concentrations, in the frequency range of 10 MHz to 10 GHz. The dielectric parameters viz. static permittivity, relaxation time, the Kirkwood correlation factor, excess permittivity, excess inverse relaxation time and thermodynamic parameters have been obtained. The calibration method based on least squares fit method has been used. The dielectric parameters show systematic change with temperature and concentrations.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.7
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• pp.521-524
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• 2010

Low loss perovskite niobates and tantalates have been placed on a short list of functional materials for future technologies. In this study, we fabricated Ag(Ta,Nb)$O_3$ thick films on the $Al_2O_3$ substrates by the screen printing method. The Ag(Ta,Nb)$O_3$ powders were fabricated by the mixed oxide method. The sintering temperature and time were $1150^{\circ}C$ and 2 hrs, respectively. The results of XRD analysis showed that the specimens employed in this study had the pesudo cubic structure. The dielectric permittivity and loss tangent of the films have been characterized from 1 kHz to 1 MHz. Also the dielectric permittivity and loss tangent were measured from 303 K to 393 K. The electrical properties of the film are also discussed.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1988.10a
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• pp.131-134
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• 1988

A finite-element method in order to invesligate the propagation characteristics of waveguide is used and most of varjational expressione of the propagation constant are a funetional of frequency. Consequently, if the permeability or permitlivity of the medium is a funetion of frequency the calculation becomes almost impossible. In this paper our method can be applied to the case where the permittivity or permeability of the media is a function of frequency and is useful for the analysis of any arbitrality dielectric wavegudie.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4158-4163
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• 2015

In this paper, the solutions of TE(transverse electric) scattering problems by a condutive strip grating over a dielectric layer are analyzed by using the FGMM(fourier galerkin moment method) and PMM(point matching method) known as a numerical method of electromagnetic fileld. The scattered electromagnetic fields are expanded in a series of floguet mode functions, the boundary conditions are applied to obtain the unknown field coefficients, and the conductive boundary condition is used for the relationship between the tangential electric field and the induced surface current density on the strip. The numerical results for the reflected and transmitted power of zeroth mode analyzed by according as the width and spacing of conductive strip, the relative permittivity and thickness of dielectric layer, and incident angles. Generally, according to the relative permittivity of dielectric layer increased, also the normalized reflected power of zeroth mode increased. To examine the accruacy of this paper, the numerical results of FGMM shown in good agreement compared to those of PMM.

• The Journal of Engineering Geology
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• v.18 no.2
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• pp.127-136
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• 2008

Geophysical survey for establishing a wide site for the distribution of water content, wetting front infiltration due to the rainfall, and distribution of groundwater level has been performed by using 8round penetration radar (GPR) method, electrical resistivity method, and so on. On the other hand, a narrow area survey was performed to use a permittivity method such as time domain reflectometry, frequency domain reflectometry, and amplitude domain reflectometry methods for estimating volumetric water content, soil density, and concentration of contaminant in surface and subsurface. The permittivity methods establish more corrective physical parameters than different found survey technologies mentioned above. In this study for establishment of infiltration behaviors for wetting front in the unsaturated soil caused by an artificial rainfall, soil physical parameters for volumetric water content, pore water pressure, and pore air pressure were measured by FDR measurement device and pore water pressure meter which are installed in the unsaturated weathered granite soil with different depths. Consequently, the authors were proposed to a new establishment method for analyzing the variations of volumetric water content and wetting front infiltration from the responses of infiltrating pore water in the unsaturated soil.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.55-58
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• 2003

This paper presents a study on the permittivities of the carbon nano fiber/epoxy composite at microwave frequency. The permittivities of composite materials depend on the concentrations and the dispersion methods of the carbon nano fibers. The experimental values of complex permittivities were obtained for the specimen made by dispersion method using ethyl alcohol as dispersion media and compared with the results by simple mechanical mixing method.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.9
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• pp.1236-1243
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• 1995

The propagation characteristics of the symmetric and the asymmetric shielded coplanar waveguide with finite metallization thickness is analyzed by boundary integral method employing the equivalence principle. Since the Green's function and the basis functions are composed of sinusoidal functions, the integration in Galerkin's method is solved analytically. The propagation constants of the fundamental and the first higher order mode are obtained and the effects of strip thickness, substrate permittivity, and the asymmetry of the structure are calculated.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.79-81
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• 2004

$TiO_2-SnO_2$ thin films are fabricated using sol-gel method. The thickness of thin films increase about $0.03{\sim}0.04{\mu}m$ every a dipping. The permittivity and dissipation factor of $TiO_2-SnO_2$ thin films decrease with increasing frequency. Thin films show semiconductive characteristics above $400^{\circ}C$.