• Title, Summary, Keyword: Dielectric constant

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A Study on the Changes in Dielectric Constant of Engine Oil (엔진오일의 유전상수 변화에 관한 연구)

  • Chun Sang-Myung
    • Tribology and Lubricants
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    • v.22 no.2
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    • pp.99-104
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    • 2006
  • The dielectric constants of fresh engine oils were obtained according to various types of oil, temperatures and frequencies. Through analyzing the characteristics of dielectric constant, the related correlation between the changes in dielectric constant of oil and the degree of oil deterioration is going to be found. The dielectric constant was calculated by cross capacitances measured by a sensor tube. Before finding the correlation, as a prerequisites study, the best condition measuring the dielectric constant was found. In general, it was found that the value of dielectric constant became stable below $60^{\circ}C$ regardless frequency variation. Further, above 6kHz, the dielectric constant became stable even if temperature had been above $100^{\circ}C$.

Study on Mutual Relation between the Level of Deterioration Influenced by the Changes of Chemical and Physical Properties and the Change of Dielectric Constant for Engine Oil - Gasoline Engine Oil (엔진오일의 화학적 및 물리적 변화에 의한 퇴화정도와 유전상수 변화에 관한 상호관계 연구 - 가솔린엔진오일)

  • Chun, Sang-Myung
    • Tribology and Lubricants
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    • v.22 no.5
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    • pp.260-268
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    • 2006
  • The dielectric constants of used gasoline engine oils were obtained at a few temperatures and a frequency. Through analyzing the characteristics of dielectric constant, the related correlation between the changes in dielectric constants of oil and the degree of oil deterioration is going to be found. The dielectric constant was calculated using cross capacitances measured by a sensor tube. As results of the measurement of the fresh engine oil's dielectric constant, it was found that the value of dielectric constant was set down below $60^{\circ}C$ regardless changing frequency. Further, above 6 kHz, the dielectric constant was set down even if temperature was above $100^{\circ}C$ Therefore, for the measurement of used oils, it was selected the frequency of 6 kHz,,and the temperature of $80^{\circ}C$ preventing a certain ionic-conduction effects on the measured dielectric constant and the evaporation of a certain fluid mixed with engine oil. Specially, the effects of the mixing fluid like coolant, water and fuel on the fresh engine oil's dielectric constant were studied. It was found that the oil mixed with coolant showed the highest value, next water, and the lowest fuel. As results of the measurement of the used engine oil's dielectric constant, it was found that the possible changed rate of the used engine oil's dielectric constant based on the warning limit for engine oil in service was below 4% for gasoline engine oil.

Study on Mutual Relation between the Level of Deterioration Influenced by the Changes of Chemical and Physical Properties and the Change of Dielectric Constant for Engine Oil - Diesel Engine Oil (엔진오일의 화학적 및 물리적 변화에 의한 퇴화정도와 유전상수 변화에 관한 상호관계 연구 - 디젤엔진오일)

  • Chun, Sang-Myung
    • Tribology and Lubricants
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    • v.22 no.5
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    • pp.290-300
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    • 2006
  • The dielectric constants of used diesel engine oils were obtained at a few temperatures and a frequency. Through analyzing the characteristics of dielectric constant, the related correlation between the changes in dielectric constants of oil and the degree of oil deterioration is going to be found. The dielectric constant was calculated using cross capacitances measured by a sensor tube. As results of the measurement of the fresh engine oil's dielectric constant, it was found that the value of dielectric constant was set down below $60^{\circ}C$ regardless changing frequency. Further, above 6 kHz, the dielectric constant was set down even if temperature was above $100^{\circ}C$. Therefore, for the measurement of used oils, it was selected the frequency of 6 kHz, and the temperature of $80^{\circ}C$ preventing a certain ionic-conduction effects on the measured dielectric constant and the evaporation of a certain fluid mixed with engine oil. Specially, the effects of the mixing fluid like coolant, water and fuel on the fresh engine oil's dielectric constant were studied. It was found that the oil mixed with coolant showed the highest value, next water, and the lowest fuel. As results of the measurement of the used engine oil's dielectric constant, it was found that the possible changed rate of the used engine oil's dielectric constant based on the warning limit for engine oil in service was below 10% for diesel engine oil.

Method for Measuring Dielectric Constant of Planar Dielectric Substrate (판형 유전체의 유전율 측정 방법)

  • Lee, Chang-Hyun;Kwon, Taek-Sun;Lee, Jeong-Hae
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.29 no.10
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    • pp.799-804
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    • 2018
  • In this paper, a method for measuring the dielectric constant of a planar dielectric substrate using the free space material constant measurement method in a general measurement environment is proposed. Two horn antennas and a network analyzer were used for S-parameter measurement and the transmission and reflection coefficients of a planar dielectric substrate were calculated from the measurement results. To obtain a reliable dielectric constant in a low-precision-measurement environment, only the magnitude of the transmission coefficient, which has a small error due to the measurement environment, is used for dielectric constant estimation. Finally, the dielectric constant is determined by comparing the measured results at different frequencies.

Dielectric Properties of Fresh Ginseng Determined by an Open-Ended Coaxial Probe Technique (수삼의 마이크로파 유전특성)

  • Hong, Seok-In;Lee, Boo-Yong;Park, Dong-June;Oh, Seung-Yong
    • Korean Journal of Food Science and Technology
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    • v.28 no.3
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    • pp.470-474
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    • 1996
  • The dielectric properties, dielectric constant (${\varepsilon}‘$) and loss factor (${\varepsilon}’$), of skin and pulp of fresh ginseng were measured from $25^{\circ}C$ to $67^{\circ}C$ using an open-ended coaxial probe technique for 915 MHz and 2450 MHz. Pulp and skin had dielectric constant of $30{\sim}64$ and loss factor between 10 and 20, each variable having a respective frequency dependence typical of materials with high water content. Although the loss factor was nearly constant, the dielectric constant increased as moisture content increased. The dielectric constant of ginseng pulp increased as temperature increased (temperature ${\leq}56^{\circ}C$), but any significant differences were not found in skin dielectric properties. Penetration depth for fresh ginseng were about 2 cm at 91.5 MHz and 1cm at 2450 MHz.

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Effect of Pressure and Solvent Dielectric Constant on the Kinetic Constants of Trypsin-Catalyzed Reaction. (Trypsin 반응에 대한 용매의 유전상수 및 압력의 영향)

  • Park, Hyun;Chi, Young-Min
    • Microbiology and Biotechnology Letters
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    • v.28 no.1
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    • pp.26-32
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    • 2000
  • Electrostatic forces contribute to the high degree of enzyme transition state complementarity in enzyme catalyzed reaction and such forces are modified by the solvent through its dielectric constant and polar properties. The contributions of electrostatic interaction to the formation of ES complex and the stabilization of transition state of the trypsin catalyzed reaction were probed by kinetic studied with high pressure and solvent dielectric constant. A good correlation has been observed between the increase of catalytic efficiency of trypsin and the decrease of solvent dielectric constant. Activation volume linearly decreased as the dielectric constant of solvent decreased, which means the increase in the reaction rae. Moreover, the decrease of activation volume by lowering the solvent dielectric constant implies a solvent penetration of the active with and a reduction of electrostatic energy for the formation of dipole of the active site oxyanion hole. When the 야electric constant of the solvents was lowered to 4.7 unit, the loss of activation energy and that of free energy of activation were 2.262 KJ/mol and 3.169 KJ/mol, respectively. The results of this study indicate that the high pressure kinetics combined with solvent effects can provide unique information on enzyme reaction mechanisms, and the controlling the solvent dielectric constant can stabilize the transition state of the trypsin-catalyzed reaction.

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Variation of Dielectric Constant of Sand due to Water Content and Measuring Frequency (수분함량과 측정주파수에 따른 사질토 지반의 유전상수 변화)

  • 이주형;오명학;박준범;김형석
    • Journal of the Korean Geotechnical Society
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    • v.18 no.6
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    • pp.129-139
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    • 2002
  • Dielectric constant measurement has drawn much attention in the investigation of the properties and contaminations of subsurface. In this study, by varying the frequency from 75 kHz to 12 MHz, dielectric constant was measured for the weathered granite soil and Jumunjin sand having different water contents and dry density. The dielectric constant of sand showed the dispersive behavior indicating that dielectric constant decreased with frequency of an electric field. And the dielectric constant of soil increased as water content and/or dry density increased due to the decrease of air portion and/or the increase of amount of water molecules which could contribute to the development of orientation polarization. The dielectric constant of sand showed a linear relationship with the moisture density, considering both water content and dry density. At low frequency, the dielectric constants calculated by Maxwell's, Topp's and CRIM equation deviated from measured values. It could be explained by the fact that those equations did not consider dispersive behavior of dielectric constant with the frequency.

열처리온도에 따른 SBN 세라믹 박막의 특성

  • Kim, Jin-Sa;Song, Min-Jong;Park, Geon-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.90-90
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    • 2009
  • The $Sr_{0.7}Bi_{2.3}Nb_2O_9$(SBN) thin films are deposited on Pt-coated electrode($Pt/Ti.SiO_2/Si$) using RF sputtering method. The dielectric constant of SBN thin films were increased with the increase of annealing temperature. The maximum dielectric constant of SBN thin film is obtained by annealing at 700[$^{\circ}C$]. The dielectric constant and dielectric loss had a stable value within -5~+5[V].

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The Change of Dielectric Constant and Leakage Current of PVA (polyvinyl alchol) by Increasing Temperature and Concentration

  • Lee, Tae-Ho;Jang, Jae-Ho;Nam, Ho-Seong;Jo, Han-Na;No, Yong-Han
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.388.1-388.1
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    • 2014
  • The performance of PVA(polyvinyl alchol) is better than another organic dielectric material. Therefore, PVA has been researched for organic and in-organic dielectric material. But research of changing PVA's dielectric constant and leakage current by increasing temperature and concentration was insigificant. We try to find pure PVA and cross-linked PVA's characteristic of dielectric by changing temperature and concentration. 5/10/15wt% PVA concentration (5% interval) was in progress, PVA at $100/150/200/250^{\circ}C$ ($50^{\circ}C$ interval) of experiments was conducted in relation to temperature. The higher the concentration, leakage currents decrease, and dielectric constant is increased. With regard to temperature, we could not see a big change of leakage current and dielectric constant of pure PVA until $200^{\circ}C$. However, we could see a tendency to increase significantly at $250^{\circ}C$. Also, leakage current and dielectric constant of cross-linked PVA gradually increased from at $100^{\circ}C$ to $200^{\circ}C$ and then sharply increased from at $250^{\circ}C$. We tried to find that PVA's inner bonds(hydroxyl group (OH-) lead to the results.

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Dielectric Properties of Complex Cconcentration in IMI-0 Thin Films (IMI-O 초박막의 착체농도에 대한 유전 특성)

  • 정상범;유승엽;박재철;권영수
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.345-348
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    • 1999
  • The monolayer behaviors at the air-water interface and the dielectric properties of MI-0 LB films for complex concentration were investigated by the surface pressure-area ($\pi$-A) isotherms and dielectric constant. The molecular area was expanded with increase of metal ions concentration. It is considered that the expansion of molecular area is due to electrostatic repulsion between the polymer chains andhydrophobic increase of ionic strength. In the frequency-dependent complex dielectric constant at room temperature, the real part of dielectric constant($\varepsilon'$) is about 6.0~10.0 in the low-frequency range and is decreasing slowly upto $1O^4$Hz. It decreased abruptly near $1O^5Hz$. It seems to be dielectric dispersion in this frequency range. Also, the imaginary part of dielectric constant ($\varepsilon"$) shows a peak in $1O^5$~$1O^6Hz$. It seems to be dielectric absorption in this frequency range.ange.

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