• Resources Recycling
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• v.12 no.6
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• pp.32-37
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• 2003

For the reduction of electromagnetic biological effects from cellular phones, the electrical field radiation from cellular phone antenna is reduced by using partial ferrite material added on the phone case as ground plane. On the given properties (permittivity, permeability and conductivity) of ferrite material, the characteristics of monopole antenna is analysed depending on the variation of ferrite added configuration(thickness and shape). According to this analysis, the design method and direction to minimize the biological effects to human head is proposed in 1.7 GHz band PCS phones. For the exact analysis involving the permittivity, per-meability and conductivity of ferrite material, FDTD numerical method is used.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.7
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• pp.1139-1146
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• 2001

A tapered impedance-matching line is designed by an inverse scattering method for the one-dimensional medium. The phase compensation factor(PCF) is introduced in order to reduce the error in the inverse scattering process to reconstruct the permittivity profile. By estimating the permittivity profile of the virtual one-dimensional dielectric medium whose reflection characteristic is the same as that of the specified matching line, the matching line is synthesized. The method can be used to design impedance-matching lines with arbitrary passband characteristics without any equivalent circuit analysis. The inevitable errors in the method using the time-domain reflection coefficient can be avoided by using the frequency-domain reflection coefficient.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.467-469
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• 2001

KAM200 which can be used electroluminescence binder is cyano material. In this study, we have fabricated KAM200 thin film by Spin-Coating method. And we have studied the electical properties of KAM200 thin films. In the I-V characteristics, the current decreases as the voltage overflow definite voltage immediately. And that definite voltage depend on thickness of KAM200 material. In the case of thickness is 1.9[$\mu\textrm{m}$], definite voltage is 7[V]. And that's electrical field 3.86[MV/m]. The dielectric properties of KAM200 thin film is investigated by measuring dielectric dispersion and absorption. KAM200's Relative dielectric constant is 10.25, and it has high permittivity compared with different materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.11a
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• pp.71-74
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• 1993

In this paper, the permeability(${\mu}$$\sub$r′/, ${\mu}$$\sub$r"/), permittivity($\varepsilon$$\sub$r′/, $\varepsilon$$\sub$r"/) and absorption properties of Ferroxplana/Rubber composites were investigated. The composite specimens were prepared by molding and curing the mixtures of matrix rubber and Ni$_2$Y ferroxplana powders which were synthesized by coprecipitated method. The permeability(${\mu}$$\sub$r′/) of specimen was decreased in the range of 8∼12.5(GHz) and the permeability(${\mu}$$\sub$r"/) and Permittivity($\varepsilon$$\sub$r′/, $\varepsilon$$\sub$r"/) were increased. The optimum thickness of electromagnetic wave absorber (F/R=4, 1,200($^{\circ}C$) ), utilizing the Smith chart, was about 3.0(mm). The Figure of Merit was 93(%).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12
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• pp.1087-1090
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• 2003

The circular cavity resonator which can measure the dielectric properties of dielectrics in the V -band(50㎓∼75㎓) frequency range was designed and fabricated. Exciting and detecting of the resonator is performed by WR15 rectangular waveguides using Bethe's small hole coupling. GaAs and PTFE plate samples were used for the verification of the performance of the fabricated circular cavity resonator. In the measurement of GaAs and PTFE using that resonator, the permittivity were measured as I2.87 and 2.14, respectively.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.5
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• pp.39-49
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• 1994

In this paper, An inversion technique to reconstruct permittivity profiles of 2-D inhomogeneous dielectric objects by iterativeprocess using the moment-methodand improved newton's algoritham is presented. In order to reduce the noise effect in the scattered fieldon the reconstructed permittivity profiles, the cell size of inversescattering is made be larger than that of forward scattering. Performing numerical calculations of dielectric scatterer it is demonstrated that this inversion is able to reconstruct dielectric objectshaving large size and inhomogeneous characteristics, which is insentive tothe noise effect in the scattered field on the reconstructed result.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.2
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• pp.69-77
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• 1996

We analyzed wideband propagation characteristics of a microstrip transmission line based on FR-4 composite substrate using the wideband complex dielectric constant model and the phenomenological loss equivalence method. The loss calculated by constant relative permittivity and loss tangent is greatly overestimatd compared to that calculated by the frequency-dependent complex relative permittivity. This wideband analysis can be helpful to characterize high-speed and high-density transmission lines associated with the wideband dielectric characteristics and shows that the FR-4 composite substrate has high potential of high frequency circuit applications in terms o fthe propagation loss.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.10
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• pp.1150-1157
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• 1988

In this paper, the reconstruction of complex permittivity distribution on a rectangular cross section of inhomogeneous dielectric cylinders is performed by employing the spectral inverse scattering scheme presented in the part I of these companion papers. Numerical simulations provide the superresolution to the permitivity profiles nearly regardless of the measurement locations of the scattered field and the permittivity distributions on the cross section.

• The Journal of the Acoustical Society of Korea
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• v.13 no.1E
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• pp.5-10
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• 1994

It is obtained the general expessions of the numerical method are applied for the TEM-mode analysis of multu-layer multi-coupled microstrip lines, In this paper, coupled microstrip are replaced by three-coupled microstrip lines in special aplications. Three-layer versions of three-coupled microstrip lines are specially attactive because of the additional flexibilities offered by three-layer configuration. This structure can be used for obtaining large capacitance and preventing coupling among microstrip lines in filter and coupler. Sappihre is chosen for anisotropic substrates material. The permittivity parallel to the optical axis is higher than the permittivity in the plane perpendicular to this axis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.135-138
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• 2003

The circular cavity resonator which can measure the dielectric properties of dielectrics in the V-band($50GHz{\sim}75GHz$) frequency range was designed and fabricated. Exciting and detecting of the resonator is peformed by WR15 rectangular waveguides using Bethe's small hole coupling. The GaAs plate sample was used for the verification of the performance of the fabricated circular cavity resonator. In the measurement of GaAs single crystal using that resonator, the resonant frequency of the dominant $TE_{011}$ mode, the permittivity and $Q{\times}f_0$ were measured as 53.29GHz, 12.87 and 138,000, respectively.