• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.10
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• pp.245-251
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• 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.

• Journal of the Optical Society of Korea
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• v.20 no.3
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• pp.431-434
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• 2016

Tris-HCl buffer solution is extensively used in biochemistry and molecular biology to maintain a stable pH for biomolecules such as nucleic acids and proteins. Here we report on the high-precision THz dielectric spectroscopy of a 10 mM Tris-HCl buffer. Using a double Debye model, including conductivity of ionic species, we measured the complex dielectric functions of Tris-HCl buffer. The fast relaxation time of water molecules in Tris-HCl buffer is ~20% longer than that in pure water while the slow relaxation time changes little. This means that the reorientation dynamics of Tris-HCl buffer with such a low Tris concentration is quite different from that of pure water.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.7
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• pp.515-521
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• 2013

Magnetoelectric(ME) bulk composites with PZT-PNN-PZN/$Fe_2O_4$ were prepared by using a conventional ceramic methods and investigated on the ME voltage vs frequency of ac magnetic fields. We made the electric equivalent circuits by using the Maxwell-Wagner model and simulated the frequency dependence of ME voltage in low frequency region. ME devices were described by a series of two equivalent circuits of piezoelectric and magnetic, which have the relaxation time ${\tau}$ due to the interaction between ME device and load resistor. Equivalent circuit of piezoelectric material is independent of frequency. However ferrite magnetic materials have Debye absorption and dipolar dispersion, whose equivalent circuit is a function of frequency. Therefore we suggest the resistance in the equivalent circuit is proportion to $1+{\omega}^2{\tau}^2$ and the capacitance is in inverse proportion to $1+{\omega}^2{\tau}^2$ in the magnetic materials.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.4
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• pp.565-574
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• 2000

A new ground penetrating radar imaging method for the estimation of buried artificial structures location and their approximate shapes in dispersive lossy ground is investigated. Fundamental idea is based on estimating delayed time and amplitude retrieval coefficients from scattered signals by buried scatterers. Using absolute value integration of each scanning site not only improve the accuracy of measured scattered signal, but also offers convenient ways to extract the image of buried structures. Multi-term Debye model was employed to describe a dispersive and lossy ground medium. We used the finite difference time domain method to discretize the wave equation in continuous form into the machine suitable form. This imaging method uses a new wave path tracing technique in time domain, which is helpful to identify the exact position of buried structures against the ground surface fluctuations.

• Journal of the Korean Magnetics Society
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• v.26 no.1
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• pp.13-18
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• 2016

The ac magnetic susceptibility was measured in iron-oxide nanoparticles with average size of 26 nm, which were uniformly dispersed in organic solvent. The ac magnetic susceptibility measured under zero magnetic fields was well fitted with Debye relaxation model and the relaxation frequency was 370 Hz. The relaxation frequency of the nanoparticles coincided with relaxation time of the Brownian motion, which is due to the viscosity of the liquid medium in which magnetic nanoparticles dwell. The Brown relaxation frequencies were linearly increased with magnetic field.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.2
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• pp.51-55
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• 2003

The interrelation into nucleation and thermodynamic parameters of solutions has been established by plotting of various dependencies: the enthalpy of dissolution, solubility product and super-solubility on ionic salt radii and also the extent of deviation from an ideal Debye -Huckel model of electrolyte solution on solubility product. The possible methods of perfect crystal growth from aqueous solution have been found a priori by separating of known set of pair values of solubility and super-solubility into no less than six-nine characteristic and distinctive sub-sets.

• Journal of the Korean Magnetics Society
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• v.9 no.6
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• pp.271-277
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• 1999

Amorphous $Fe_{83}B_9Nb_7Cu_1$ alloy has been studied by M$\"{o}$ssbauer spectroscopy. Revised Vincze method was used and distributions of hyperfine field, isomer shift, and quadrupole line broadening of the sample at various temperatures have been evaluated and Curie temperature and $H_{hf}\;(0)$ were calculated to be 393 K and 231 kOe, respectively. Temperature variation of reduced average hyperfine field shows a flattered curvein comparison with the Brillouin curve for S=1. This behavior can be explained on the basis of Handrich molecular field model, in which the parameter Δ, which is a measure of fluctuation in exchange interactions, is assumed to have the temperature dependence ${Delta}=0.75-0.64{\tau}+0.47{\tau}^2$ where $\tau$ is $T/T_C$. At low temperature, the average hyperfine field can be fitted to $H_{hf}\;(T)=H_{hf}\;(0)\;[1-0.44\;(T/T_C)^{3/2}-0.28(T/T_C)^{5/2}-… ]$, which indicates the presence long wave length spin wave excitations. At temperature near TC, reduced average hyperfine field varies as $1.00\;[1-T/T_C]^{0.39}$. It is also found that half-width of the hyperfine field distribution was 102 kOe (3.29 mm/s) at 13 K and decreased monotonically as temperature increased. Above the Curie temperature, an average quadrupole splitting value of 0.43 mm/s was found. Average line broadening due to quadrupole splitting distribution was 0.31 mm/s at 13 K and decreases monotonically to 0.23 mm/s at 320 K, whereas that due to the isomer shift distribution is 0.1 mm/s at 13 K and 0.072 mm/s at 320 K, which is much smaller than that of both hyperfine field and quadrupole splitting. The temperature dependence of the isomer shift can be fitted within the harmonic approximation to a Deybe model with a Debye temperature ${Theta}_D=424{\pm}5K$.TEX>.

• Polymer(Korea)
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• v.26 no.6
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• pp.728-736
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• 2002

The thermal and dielectric properties of unsaturated polyester resin system during cure were analyzed under Isothermal conditions. Both $varepsilon$′ and $varepsilon$" decreased and dipole relaxation was observed under isothermal conditions during cure. The ionic conductivity decreased linearly with the conversion according to the Kienle-Rate equation (ln($varepsilon$"$_{ionic}$we$_{0}$)=C$_{r}$$alpha$+C$_{0}$) up to $alpha$=0.15, after which it aparted from the relationship due to the entanglement of polymer chains. The effect of ionic conductivity was revealed to be larger than that of dipole motion during the whole cure through the electrical modulus analysis. Although dielectric motion was analyzed with Debye model, it was observed only at a narrow time region of middle stage of cure. In order to estimate the dielectric properties during the whole cure, the Havriliak-Negami model was considered and modified with the strong effect of ionic conductivity. The changes of $varepsilon$′ and $varepsilon$" were well estimated with this modified Havriliak-Negami model.

• Membrane Journal
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• v.12 no.4
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• pp.207-215
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• 2002

The hindered diffusion in confined spaces is an important phenomenon to understand in a micro-scale the filtration mechanism determined by the particle motion in membrane pores. Compared to the case of spherical colloids, both the theoretical investigations and the experiments on the hindered diffusion of polyelectrolytes is actually more difficult, due to lots of relevant parameters resulting from the complicated conformational properties of the polyelectrolyte chain. We have successfully performed the Brownian dynamics simulations upon a single polyeiectrolyte confined in a slit-like pore, where a coarse-grained bead-spring model incorporated with Debye-Huckel interaction is properly adopted. For the given sizes of both the polyelectrolyte and the pore width, the hindered diffusion coefficient decreases as the solution ionic concentration decreases. It is evident that a charge effect of the pore wall enhances the hindered diffusion of polyelectrolyte. Simulation results allow us to make sense of the diffusive transport through the micro-pore, which is restricted by the influences of the steric hindrance of polyelectrolytes as well as the electrostatic repulsion between the polyelectrolytes and pore wall.

• Journal of electromagnetic engineering and science
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• v.10 no.4
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• pp.231-236
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• 2010

This study proposes a temperature compensation method of the complex permittivities of biological tissues and organs. The method is based on the temperature dependence of the Debye model of water, which has been thoroughly investigated. This method was applied to measured data at room temperature for whole blood, kidney cortex, bile, liver, and heart muscle. It is shown that our method can compensate for the Cole-Cole model using measured data at 20 $^{\circ}C$, given the Cole-Cole model based on measured data at 35 $^{\circ}C$, with a root-mean-squared deviation of 3~11 % and 2~6 % for the real and imaginary parts of the complex permittivities, respectively, among the measured tissues.