• 제목/요약/키워드: Dielectric constant

검색결과 2,735건 처리시간 0.034초

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

  • 전상명
    • Tribology and Lubricants
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    • 제22권2호
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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 $100^{\circ}C$.

엔진오일의 화학적 및 물리적 변화에 의한 퇴화정도와 유전상수 변화에 관한 상호관계 연구 - 가솔린엔진오일 (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)

  • 전상명
    • Tribology and Lubricants
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    • 제22권5호
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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.

엔진오일의 화학적 및 물리적 변화에 의한 퇴화정도와 유전상수 변화에 관한 상호관계 연구 - 디젤엔진오일 (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)

  • 전상명
    • Tribology and Lubricants
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    • 제22권5호
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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.

The estimation of dielectric constant of thick film using Vickers indentation

  • Kim, Hyeong-Jun;Kim, Kibum;Kim, Jongcheol;Yoon, Kyung-Han;Shin, Dongwook
    • Journal of Ceramic Processing Research
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    • 제13권spc2호
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    • pp.241-245
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    • 2012
  • The barrier rib on plasma display panel (PDP) is a typical 3D-patterned thick film with thickness of 120 ㎛ and it is hard to measure its dielectric constant in this state of the product. Because the porosity of ceramic thick film influenced the mechanical and dielectric characteristics, it was expected that there was the relationship between two properties. Therefore, the correlation analysis between porosity, hardness and dielectric constant of the barrier rib was studied and the exponential curve between porosity and hardness, and the quadratic curve between porosity and dielectric constant were drawn. The dielectric constant was well related to hardness by K400kHz = 0.5672 + 5.695 ln(Hv). The hardness was measured at five points on two real panels which sintered by two types of profiles and then dielectric constants and deviation were estimated by the above equation.

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

  • 이창현;권택선;이정해
    • 한국전자파학회논문지
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    • 제29권10호
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    • pp.799-804
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    • 2018
  • 본 논문에서는 일반 측정환경에서 자유공간 물질상수 측정법을 사용한 판형 유전체의 유전율 측정 방법을 제안한다. 측정에는 회로망분석기와 동일한 두 개의 혼 안테나가 S-parameter 측정을 위해 사용되었으며, 측정 결과로부터 판형 유전체의 투과 및 반사계수를 계산하였다. 정밀한 측정을 할 수 없는 환경에서 신뢰할 수 있는 유전율을 얻기 위하여 상대적으로 측정 환경에 의한 측정불확도가 작은 투과계수의 크기만을 유전율 추정에 이용하였으며, 최종적으로 다양한 주파수에서 측정된 결과를 비교하여 유전율을 특정하였다.

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

  • 홍성호;강문식
    • Tribology and Lubricants
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    • 제37권6호
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    • pp.203-207
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    • 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.

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

  • 홍석인;이부용;박동준;오승용
    • 한국식품과학회지
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    • 제28권3호
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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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Trypsin 반응에 대한 용매의 유전상수 및 압력의 영향 (Effect of Pressure and Solvent Dielectric Constant on the Kinetic Constants of Trypsin-Catalyzed Reaction.)

  • 박현;지영민
    • 한국미생물·생명공학회지
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    • 제28권1호
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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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열처리온도에 따른 SBN 세라믹 박막의 특성

  • 김진사;송민종;박건호
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2009년도 추계학술대회 논문집
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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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수분함량과 측정주파수에 따른 사질토 지반의 유전상수 변화 (Variation of Dielectric Constant of Sand due to Water Content and Measuring Frequency)

  • 이주형;오명학;박준범;김형석
    • 한국지반공학회논문집
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    • 제18권6호
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    • pp.129-139
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    • 2002
  • 최근 지반 특성과 지반 오염도의 조사를 위해 유전상수 측정기법을 적용하기 위한 연구가 활발히 진행되고 있다. 본 연구에서는 다양한 함수비와 건조단위중량을 갖는 화강풍화토와 주문진표준사의 유전상수를 75kHz~12MHz의 주파수 범위에서 측정하였다. 사질토의 유전상수는 주파수가 증가함에 따라 감소하는 분산거동을 보였다. 또한 함수 비나 건조단위중량이 증가함에 따라 배향분극에 기여하는 물분자의 양이 증가하고 유전상수가 1인 공기의 양이 감소하여 유전상수가 증가하였다. 흙의 유전특성은 함수비와 건조단위중량을 모두 고려한 수분밀도에 선형적으로 비례하는 경향을 나타내었다. Maxwell식, Topp식, CRIM식에 의한 계산값과 측정된 값을 비교한 결과 기존의 식은 유전상수의 분산거동을 고려하지 못하고 있기 때문에 저주파에서는 측정값과 차이를 나타내었다.