• The Journal of Engineering Geology
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• v.14 no.2
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• pp.179-187
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• 2004

This study conducted a laboratory work to determine the change of dielectric constant of saturated soil porous media, which is injecting EML to use Frequency Domain Reflectometry(FDR) system and length 7cm-length measurement sensor. It is purpose of study that estimate a movement path through pore of soil for an ethanol mixing liquid(EML) which have the same specific gravity of water at $20{\;}^{\circ}C$, and determine to a dielectric measuring range for the measurement sensor. As an outflow point of saturated soil column upper part recedes from an EML inject point in EML diffusion test, the diffusion extent of EML through pore of saturated soil was expanded. And results of ail EML flow experiment were measured the change of dielectric constant at all measurement sensors which are placed to constant interval at the same travel time for saturated soil column. Therefore, the displace process of water that exist in pore of saturated soil by EML injection is enough available and confirm together mobility through pores.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1752-1758
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• 2018

In a low-voltage distribution system, the molded case circuit breaker (MCCB) is a widely used device to protect loads by interrupting over-current; however the hot gas generated from the arc discharge in the interrupting process depletes the dielectric recovery strength between electrodes and leads to re-ignition after current-zero. Even though the circuit breaker is ordinarily tripped and successfully interrupts the over-current, the re-ignition causes the over-current to flow to the load again, which carries over the failure interruption. Therefore, it is necessary to understand the dielectric recovery process and the dielectric recovery voltage of the MCCB. To determine these characteristics, a measuring system comprised of the experimental circuit and source is implemented to apply controllable recovery voltage and over-current. By changing the controllable recovery voltage, in this work, re-ignition is driven repeatedly to obtain the dielectric recovery voltage V-t curve, which is used to analyze the dielectric recovery strength of the MCCB. A measuring system and an evaluation technique for the dielectric recovery strength of the MCCB are described. By using this system and method, the measurement to find out the dielectric recovery characteristics after current-zero for ready-made products is done and it is confirmed that which internal structure of the MCCB affects the dielectric recovery characteristics.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.747-754
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• 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.

• Journal of Biosystems Engineering
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• v.24 no.2
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• pp.123-134
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• 1999

The electrical properties such as dielectric constant, dielectric loss factor and AC conductivity of grain were presented to measure the moisture content of grain using RF impedance. At frequency ranging from 1 to 10MHz and room temperature, $20^{\circ}C$, vector network analyzer(HP4195) and coaxial type sample holder were used to analyze the electrical properties of paddy(11∼24%w.b.), brown rice(11∼18%w.b.), barley(11∼21%w.b.) and wheat(11∼23%w.b.) depending on the moisture content, frequency and bulk density. The dielectric constant and AC conductivity of grain samples increased with moisture content and bulk density. The dielectric constants decreased with frequency and could be expressed as function of the moisture density(decimal moisture $content{\times}bulk$ density).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.309-313
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• 1997

(Ba$_{x}$Sr$_{l-x}$)TiO$_3$(BST) thin fi1ms with various Ba/Sr ratios were deposited on Pt(80nm)/SiO$_2$(100nm)/Si by RF magnetron sputtering. BST thin films which have x=0.6, 0.5, 0.4 were studied dielectric properties with temperature variation. The frequency was used from 100Hz to 1MHz for measuring dielectric constant. The measurement conditions of dielectric constant with Temperature Variation were 1KHz and 2$0^{\circ}C$. As a result, the dielectric constant of BST thin film was about 425 and loss factor was 0.013. Also, with increasing Temperature, the dielectric constants of BST thin films were gradually decreased.sed.

• Bulletin of the Korean Chemical Society
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• v.20 no.11
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• pp.1329-1334
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• 1999

The curing characteristics of diglycidyl ether of bisphenol A (DGEBA) with diaminodiphenylmethane (DDM) as a curing agent were studied using differential scanning calorimetry (DSC), rheometrics mechanical spectrometry (RMS), and dielectric analysis (DEA). The isothermal curing kinetics measured by DSC were well represented with the generalized auto-catalytic reaction model. With the temperature sweep, the inverse relationship between complex viscosity measured by RMS and ionic conductivity obtained from DEA was established indicating that the mobility of free ions represented by the ionic conductivity in DEA measurement and the chain segment motion as revealed by the complex viscosity measured from RMS are equivalent. From isothermal curing measurements at several different temperatures, the ionic conductivity contribution was shown to be dominant in the dielectric loss factor at the early stage of cure. The contribution of the dipole relaxation in dielectric loss factor became larger as the curing further proceeded. The critical degrees of cure, at which the dipolar contribution in the dielectric loss factor starts to appear, increases as isothermal curing temperature is increased. The dielectric relaxation time at the same degree of cure was shorter for a sample cured at higher curing temperature.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.2
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• pp.139-143
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• 1988

A new measurement method of coupled transmission line characteristics is described. This method presents precision values of even-and odd-mode impedances as well as effective dielectric constants of symmetric parallel coupled microstrip lines from the scalar quantities obtained by transmission coefficients at two different resonance frequencies. Especially these values include dispersion effects in the measured frequency band. The measured impedances and effective dielectric constants of actually fabricated coupled lines on the Teflon substrates with low dielectric constants are good agreement with predicted values. And the experimental pass band characteristics of single section resonator by using previously designed coupled lines agree well with theoretical values.

• Journal of the Korean Institute of Telematics and Electronics
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• v.7 no.2
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• pp.43-48
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• 1970

The precise measurement technique for dielectric constent of high-loss nonmagnetic materials is described. This technique use6 is based upon cavity resonance method and impedance method. Dielectric constant can be calculated from simple formulas without using transcen-dental equations. The error contained in x-band yields loss tangent, 3%, and dielertric constant, 1%, for materials filled in cross section of waveguide.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.05a
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• pp.125-129
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• 1992

When relaxation time will be distributed, TSC observed in the experimental procedure was analysed by using a potential model having two equilibrium positions and equations of dielectric properties was derived. Calculation of distribution was made by matrix method and compared/confirmed values obtained by TSC and alternating current which have a correspondence with each other. In this measurement, distribution of activation energy and relaxation time was determined by TSC peak at around 147k/364 of which center is 10$\^$-4/ sec/10$\^$5/ sec respectively at room temperature and also obtained dielctric loss factor at the range of 10$\^$-7/-10$\^$5/Hz. It seems that low temperature peak is local dispersion and high temperature peak have a relation to dielectric transition of the material.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.11
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• pp.730-735
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• 2014

In this study, the temperature characteristics of electrostatic capacity and dielectric loss for the sample of Teflon film which is degradated at the $120^{\circ}C{\sim}200^{\circ}C$ temperature range in the oven for 10 hours has been measured in through the applied frequency range of 0.1 kHz~4,800 kHz at temperature of $50^{\circ}C$, $90^{\circ}C$, $130^{\circ}C$, $170^{\circ}C$. Also, in the same conditions, the frequency characteristics of electrostatic capacity and dielectric loss for the sample of Teflon film has been measured in through the applied temperature range of $30^{\circ}C{\sim}70^{\circ}C$ on setting frequency of 0.1 kHz, 1 kHz, 10 kHz, 100 kHz. The results of this study are as follows. When the frequency range of 0.1 kHz~4,800 kHz applied to the sample of Teflon film, the electrostatic capacity has been measured at the temperature of $50^{\circ}C$, $90^{\circ}C$, $130^{\circ}C$, $170^{\circ}C$. Through this measurement, it found that the electrostatic capacity decreased with increasing temperature. Regarding this result, may be it is because the electromagnetic coupling is degraded by thermal degradation. When the sample of Teflon film heated at $280^{\circ}C$ for 10 hours in oven, the dielectric loss has changed from unstable status to stabilizing status with increasing the degradation temperature in the $120^{\circ}C$, $160^{\circ}C$, $200^{\circ}C$ range. In this measurement, the two spectrums of dielectric loss appeared. It considers that this spectrum of dielectric loss appeared in 300 Hz is caused by the molecular motion of the C-F or OH group. Through this study, It found that the electrostatic capacity decreased with increasing frequency and temperature, and there is no change in dielectric loss, although the frequency increases.