• Journal of the Korean Society for Nondestructive Testing
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• v.37 no.1
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• pp.1-6
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• 2017

In this study, a terahertz time domain spectroscopy (THz-TDS) imaging technique was used to measure doping concentration and physical properties (such as refractive index and permittivity) of the doped silicon (Si) wafers. The transmission and reflection modes with an incidence angle of $30^{\circ}$ were employed to determine the physical properties of the doped Si wafers. The doping concentrations of the prepared Si wafers were varied from $10^{14}$ to $10^{18}$ in both N-type and P-type cases. Finally, the correlation between the doping concentration and the power of the THz wave was determined by measuring the powers of the transmitted and reflected THz waves of the doped Si wafers. Additionally, the doped thickness, the refractive index, and permittivity of each doped Si wafer were calculated using the THz time domain waveform. The results indicate that the THz-TDS imaging technique is potentially a promising technique to measure the doping concentration as well as other optical properties (such as the refractive index and permittivity) of the doped Si wafer.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.2
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• pp.218-226
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• 1999

This paper describes resonant mode selection with which the relative permittivity can be measured exactly. To measure the relative permittivity, a circular cylindrical cavity filled with dielectric material is used. When the circular cylindrical cavity is filled with the dielectric material, the air gap occurs on account of machining error. Accurate relative permittivity can be obtained by using less sensitive mode in resonant frequency variation by the air gap. As a result, Average 0.009% resonant frequency variation in the vertical and the radial direction appears at $TE_{011}$ mode. It is interesting that the frequency variation by the air gap at $TE_{011}$ mode turns out to be the least sensitive.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1803-1805
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• 1999

The thermal expansion coefficient of the titania-fused silica glass$(TiO_2-SiO_2)$ called KLR-1.1 is known to $0{\pm}0.03$ ppm/K, while that of normal fused-silica glasses is about +0.5 ppm/K at room temperature. To analysis the dielectric properties of the KLR-1.1, the sample with diameter of 30 mm and thinkness of 1 mm is covered with gold film. Its relative permittivity and dissipation factor of KLR-1.1 is evaluated to $4.011{\pm}0.012(1\sigma)$ and $(4.86{\pm}0.02){\times}10^{-4}(1{\sigma})$ at 1 kHz respectively. The measurement techniques used and results are more discussed in this paper.

• 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
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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.

• 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.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2297-2299
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• 2005

In this paper, a finite element (FEM) investigation of composite materials is studied. A pemittivity profile of the material is implemented to correspond to the Packing fraction of the physical composite. Curve fitting is applied to the standing wave pattern to determine the effective attenuation coefficient and propagation constant in the composite. The complex permittivity as a function of packing density is then determined. A comparison between the two dimensional and three dimensional measurement simulations is presented. An adaptive scheme is implemented to improve resolution of the finite element particulates.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.1
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• pp.9-15
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• 2011

This paper suggested the fast and easy method of the dielectric constant measurement for planar dielectrics using a microstrip line. The complex permittivity and permeability were presented by the first reflection and transmission coefficient which were derived from the scattering parameters. This method was verified by the measurement of a known planar dielectric using a microstrip line. This method can be applied to the dielectric constant measurement of unknown planar dielectric.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.10
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• pp.971-981
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• 2002

An open-ended coaxial probe method has been considered as one of effective tools for measuring electrical properties of its contacted material without shaping and fitting. The measured reflection coefficient at the probe's end is able to convert into the corresponding complex permittivity by employing the improved version of virtual transmission-line model Presented by our lab already. But the error of complex permittivity converted by equivalent model increases as the operating frequency ascends high. The errors of complex permittivity in the open-ended coaxial probe can be yielded compositively by the imperfect contact or probe, manufacture error of probe and complex permittivity error of reference material etc. Therefore it is necessary to limit the problem to identify the error causes in high frequency. In this paper, the errors which are resulted from the measurement of reflection coefficient are removed by using the FDTD(Finite-Difference Time-Domain) method, the error causes are limited the conversion model problem. And the error study of the improved conversion model is performed from several viewpoints. At first, the local minimum of parameter to be calculated by the iteration method in the conversion model is checked. At second, the modeling of the equivalent model is checked in the frequency range. From this study, we know the valid range of the improved conversion model.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.3
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• pp.252-261
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• 1988

Employed the new invese scattering scheme based on the moment mehtod, which was presented in the Part I of these companion papers, numerical simulations are performed to investigate the effect of measurement errors and noise contaminating the field scattered from dielectric objects. In order to reduce those effects on the reconstructed permittivity profiles, some techniques such as regularization, iterative matrix inversion, and multiple incidence are applied to this problem.