• Title/Summary/Keyword: dielectric constant

Search Result 2,495, Processing Time 0.666 seconds

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

  • Chun Sang-Myung
    • Tribology and Lubricants
    • /
    • v.22 no.2
    • /
    • pp.99-104
    • /
    • 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
    • /
    • v.22 no.5
    • /
    • pp.260-268
    • /
    • 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
    • /
    • v.22 no.5
    • /
    • pp.290-300
    • /
    • 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.

Dielectric Constant Anomaly near the Consolute Point of a binary Mixture of MEEP and water (상전이 온도 근처에서 관찰되는 MEEP-물로 구성된 두 종류 섞임체의 유전상수 비정상성)

  • Cho, Chang-Ho;Seo, Young-Seok;Kim, Sei-Chang;Kim, Young-Baek
    • The Journal of Natural Sciences
    • /
    • v.8 no.1
    • /
    • pp.17-22
    • /
    • 1995
  • Dielectric constant was measured near the consolute point of a binary mixture of water and Poly[bis(methoxyethoxyethoxy)phosphazene], MEEP. Dielectric constant changed incontinously at phase separation temperature plotted against the concentration to abtain coexistence curve. The critical temperatures and the critical concentration were $71^{\circ}C$, 5.5% as determined from the coexistence curve, respectivley. The critical exponent of dielectric constant, $\theta$, was 0.85. The dependence of dielectric constant on frequency is discussed in this report.

  • PDF

Calculation of Field Enhancement Factor in CNT-Cathodes Dependence on Dielectric Constant of Bonding Materials

  • Kim, Tae-Sik;Shin, Heo-Young;Cho, Young-Rae
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 2005.07b
    • /
    • pp.1092-1095
    • /
    • 2005
  • The effect of the dielectric constant (${\varepsilon}$) of bonding materials in screen-printed carbon nanotube cathode on field enhancement factor was investigated using the ANSYS software for high-efficient CNT-cathodes. The field enhancement factor increased with decreasing the dielectric constant and reaching a maximum value when the dielectric constant is 1, the value for a vacuum. This indicates that the best bonding materials for screen-printing CNT cathodes should have a low dielectric constant and this can be used as criteria for selecting bonding materials for use in CNT pastes for high-efficient CNT-cathodes

  • PDF

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
    • /
    • v.18 no.6
    • /
    • pp.129-139
    • /
    • 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.

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
    • /
    • v.28 no.1
    • /
    • pp.26-32
    • /
    • 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.

  • PDF

Development of Dielectric Constant Sensor for Measurementof Lubricant Properties (윤활유 물성 측정을 위한 유전상수 센서 개발)

  • Hong, Sung-Ho;Kang, Moon-Sik
    • Tribology and Lubricants
    • /
    • v.37 no.6
    • /
    • pp.203-207
    • /
    • 2021
  • This study presents the development of dielectric constant sensors to measure lubricant properties. The lubricant oil sensor is used to measure oil properties and machine conditions. Various condition monitoring methods are applied to diagnose machine conditions. Machine condition monitoring using oil sensors has advantage over other machine condition monitoring methods. The fault conditions can be noticed at the early stages by the detection of wear particles using oil sensors. Therefore, it provides an early warning in the failure procedure. A variety of oil sensors are applied to check the machine condition. Among all oil sensors, only one sensor can measure the tendency of several properties such as acidity and water content. A dielectric constant sensor is also used to measure various oil properties; therefore, it is very useful. The dielectric constant is the ratio of the capacitance of a capacitor using that material as a dielectric to that of a similar capacitor using vacuum as its dielectric. The dielectric constant has an effect on water content, contaminants, base oil, additive, and so forth. In this study, the dielectric constant sensor is fabricated using MEMS process. In the fabrication process, the shape, gap of the electrode array, and thickness of the insulation material are considered to improve the sensitivity of the sensor.

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
    • /
    • 2009.11a
    • /
    • pp.90-90
    • /
    • 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].

  • PDF

Study on Availability about the Dielectric Constant of SiOC Thin Film (SiOC 박막의 허용 가능한 유전상수 설정에 대한 연구)

  • Oh, Teresa
    • Journal of the Korean Vacuum Society
    • /
    • v.19 no.5
    • /
    • pp.347-352
    • /
    • 2010
  • To research the reduction of the dielectric constant depending on the ionic and electronic effects, the dielectric constant of SiOC film was obtained by C-V measurement using the structure of metal/SiOC film/Si, and $n^2$ calculated by the refractive index. The dielectric constant of SiOC film consists with dipole, ions and electrons. However, the dipole moment is ignored in the effect of dielectric constant in SiOC film. THe SiOC film was deposited by the plasma energy, and the gas precursor was dissociated and recombined. Therefore, the dielectric constant of the deposited film consisted of the polarity with ions. THe dielectric constant decreased after annealing process, because of the evaporation of OH hydroxyl group with polarity. The ideal SiOC film as low-k materials was annealed film with lowering the polarity, which is suitable for physical-chemical and electrical properties as an inter layer dielectric materials.