• Title, Summary, Keyword: Permittivity

Search Result 784, Processing Time 0.034 seconds

ELDCTRICAL COMPUTED TOMOGRAPHY FOR IMAGING OF INTERNAL RESISTIVITY AND PERMITTIVITY DISTRIBYTION

  • Kurniad, Deddy;Komiya, Kin-ichi
    • 제어로봇시스템학회:학술대회논문집
    • /
    • /
    • pp.578-582
    • /
    • 1994
  • In this paper reconstructing the internal resistivity and relative permittivity distribution is discussed. The iterative reconstruction method based on Finite Element method and Newton method were used to reconstruct both of resistivity ind permittivity distribution. The Finite Element model of impedance distribution is built in complex field of resistivity and capacitive medium. The reconstruction results based on computer simulated data and experimental data are presented.

  • PDF

A New Inverse Scattering Scheme Using the Moment Method, I: Theory (모멘트방법을 이용한 새로운 역산란 계산 방법, I : 이론)

  • 김세윤;이재민;라정웅
    • Journal of the Korean Institute of Telematics and Electronics
    • /
    • v.25 no.3
    • /
    • pp.243-251
    • /
    • 1988
  • A new technique to reconstruct complex permittivity profiles of dielectric objects by using the moment-method solutions to the electric field integral equation iversely is presented here. Performing numerical calcualtions for several type of dielectric objects by employing the present scheme, it is demonstrated that this inverse technique provides the superresolution of the reconstructed permittivity profiles regardless of the location measured the scattered field, the size and shape of dielelctric objects and the permittivity profile.

  • PDF

A study on the measuring of relative permittivity of microwave PCB with frequency for the numerical analysis of EMI (EMI 수치해석을 위한 주파수에 따른 마이크로파 인쇄회로기판의 비유전율의 측정에 관한 연구)

  • Jang, In-Bum;Kim, Yong-Chun;Kim, Chung-Heok;Lee, Joon-Ung
    • Proceedings of the KIEE Conference
    • /
    • /
    • pp.308-310
    • /
    • 1997
  • In this paper, to anlayze electromagnetic distribution, measure the variation of relative permittivity of Glass-epoxy substrate for Computer-main-board and Tenon substrate for handphone or PCS in the frequency range $100[MHz]{\sim}1[GHz]$, in room temperature. To measure relative permittivity, suggested the Microstripline method. As the frequency increase, the variation of relative permittivity of Glass-epoxy is bigger than Tefoln's. And simulate the electromagnetic distribution on the PCBs in the infinite region applying the open boundary condition with these results by Finite Element Method.

  • PDF

A Study on the Dielectric Properties of Epoxy Composites due to Temperature Variation (온도변화에 따른 에폭시 복합체의 유전특성에 관한 연구)

  • 김상걸;송봉철;정동회;이호식;이원재;이준웅
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • /
    • pp.148-151
    • /
    • 2000
  • In this paper, the dielectric properties of epoxy composites used for transformers are studied. The dielectric permittivity and loss of specimen are measured at the temperature range of 20[$^{\circ}C$]~150[$^{\circ}C$] about frequency 30[Hz], 1[kHZ] and 30[kHz] respectively from a series of experiments. Consequently, observed higher values of dielectric permittivity and loss in filled epoxy are attributed to Maxwell-Wagner Polarization effect. Also, glass transition temperature was shifted to higher temperature and value of dielectric permittivity and loss were decreased due to 2nd curing.

  • PDF

The Characteristics of Electromagnetic Wave Absorption in Sintered and Composite Ni-Zn Ferrites (니켈-아연 페라이트 소결체와 복합체의 전파흡수특성)

  • 조성백;오재희
    • Journal of the Korean Ceramic Society
    • /
    • v.32 no.1
    • /
    • pp.25-30
    • /
    • 1995
  • The frequenc dependence of magnetic permeability($\mu$r) and dielectric constant($\varepsilon$r) in MHz-GHz frequency range and their relationships with microwave absorbing properties were investigated in sintered and composite Ni-Zn ferrites, respectively. It was confirmed that zero reflection condition was required the real parts of permeability and permittivity in sintered specimen, and the complex permeability, permittivity and dielectric loss tangent in composite specimen. The real part of permittivity varied with the replacement of nickel by manganese in sintered Ni-Zn ferrite. Therefore, we could control the matching frequency and matching thickness.

  • PDF

Frequency-dependent electrical parameters of soils as a function of the moisture content (수분함유량에 따른 토양의 전기적 파라미터의 주파수의존성)

  • Lee, Bok-Hee;Kim, Ki-Bok
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.28 no.6
    • /
    • pp.68-74
    • /
    • 2014
  • The electrical parameters of soils are highly dependent on the various factors such as types of soil, chemical compositions, moisture content, temperature, frequency, and so on. The analysis of soil parameters is of fundamental importance in design of grounding systems. In this paper, we present the experimental results of frequency-dependent impedance, resistivity, permittivity of soils as functions of types of soil and moisture content. The impedance and resistivity of soils are decreased as the moisture content and the frequency increase. In particular, the variation of the soil resistivity with the frequency is pronounced in the conditions of high resistivity and low moisture content. On the contrary, the permittivity of soils are sharply decreased with increasing the frequency below 10kHz and the frequency-dependent permittivity of soils are highly changed in the conditions of high moisture and low resistivity.

Numerical Calculation for Impedance of Horizontal Ground Electrode for Information and Communication Facilities with Considering Characteristics of Permittivity in Soil (토양의 유전율 특성을 고려한 정보통신설비용 수평접지전극의 임피던스 계산)

  • Ahn, Chang-Hwan
    • Journal of the Institute of Electronics and Information Engineers
    • /
    • v.50 no.10
    • /
    • pp.245-251
    • /
    • 2013
  • An impedance of ground electrode for information and communication facilities has a significant relationship with the electrical characteristics of soil where the ground electrode is buried. Especially, the impedance of ground electrode is directly affected by the characteristics of permittivity and conductivity in soil as a function of a frequency of an applied electric field. The program based on the electromagnetic field model was developed in MATLAB. Because both permittivity and conductivity can not be modified in commercial programs. The permittivity of soil was applied with the Debye equation which is a model of dielectric relaxation. And the empirical equation of the conductivity in soil was quoted in other paper. In order to confirm the reliability of proposed program, the impedance measurement of ground electrode was carried out, which were compared with the results of simulation in commercial program. In result, it was confirmed that the impedance and phase different simulated by appling the characteristics of permittivity and conductivity in soil are in good agreement with the measured values than results of NEC.

A Fabrication of From and a Measurement of Relative Permittivity of Illite Found in Young-dong Area (영동산 일라이트의 성형 및 비유전율 측정)

  • Lee, Won-Hui;Choi, Hong-Ju;Koo, Kyung-Wan;hur, Jung
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.12 no.5
    • /
    • pp.747-754
    • /
    • 2001
  • This paper describes measurement of relative permittivity of illite found in young-dong area. A measurement of relative permittivity of the illite was made using cylindrical cavity resonators with a moveable cap. A concentric dielectric-rod inserted the cylindrical cavity resonator and an exact field representation of non-decaying mode of the resonator are introduced for the measurement of relative permittivity. The exact electromagnetic fields in cylindrical cavity with a concentric dielectric rod is analysed. The relative permittivity of dielectric in the cavity is calculated by analyzing a characteristic equation. The characteristic equation is solved by using the ContourPlot graph of Mathematica. We know that the field representation of non-decaying mode is exact. As a result, the relative permittivity of dielectric materials was 7.820 for a sample with binder and 7.894 for a pure sample.

  • PDF

Variations of Complex Permittivity due to Water Content and Heavy Metal Contamination (함수비와 중금속 오염도에 따른 유전상수의 변화)

  • Oh Myoun-Hak;Kim Yong-Sung;Yoo Dong-Ju;Park Jun-Boum
    • Journal of the Korean Geotechnical Society
    • /
    • v.21 no.5
    • /
    • pp.231-241
    • /
    • 2005
  • Laboratory experiments were performed to examine the effects of water content and to see if permittivity had sufficient sensitivity to identify subsurface contamination. Both real and imaginary permittivities of unsaturated sand were strongly governed by the volumetric water content. Especially, a linear relationship between real permittivity and volumetric water content was derived at high frequencies (MHz ranges). Heavy metals in pore fluid result in significant increases in the effective imaginary permittivity, due to ionic conduction, but decreases in the real permittivity arises due to the decreased orientational polarization of water molecules caused by hydration of ions. Clear increase in the effective imaginary permittivity with heavy metal concentration was found to be valuable in the application of electrical methods for detecting heavy metals in the subsurface. However, because the permittivity is primarily dependent on the volumetric water content of soil, pre-evaluation on the volumetric water content is required.

A Study on the Photon Energy Characteristics of ZnO Thin Film According to Coating Thickness (ZnO 박막의 증착 두께에 따른 Photon Energy 특성에 관한 연구)

  • Lee, Jung-Il;Seo, Jang-Soo;Jung, Sung-Gyo;Kim, Byung-In
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • /
    • pp.75-81
    • /
    • 2003
  • This study evaporates ZnO layer thickness differently with RF sputtering method on Si Wafer(n-100). This study is performed to examine the characteristics of photon energy and dielectric loss according to the thickness of ZnO and increase the reliability and reproduction of ZnO thin film. It is confirmed that the variation of electric Permittivity by frequency is resulted from the formation of particles within thin film, the particle size and the polarization on grain boundary. Peak of electric Permittivity value of thin film has slower and less value in early low wavelength by the coulomb force involved in carrier combination according to the increase of frequency. Reversal of electric Permittivity values is induced by dipole polarization shown in the dielectric of thin film. Complex electric constant $({\varepsilon}_1{\varepsilon}_2)$ has larger peak values as it’s thickness is thinner and then it is larger according to the increase of frequency. Electric Permittivity by photon energy has large value in imaginary number and is reduced exponentially by the increase of carrier density according to that of photon energy.

  • PDF