• 한국산업정보학회논문지
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• 제9권2호
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• pp.59-64
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• 2004

우리가 일반적으로 다루는 많은 대상들은 대부분 복잡하고 불규칙적인 형태를 지니고 있다. 이로 인해 보통 사용하는 미분연산자와 같은 전통의 수학적 기법들은 경우에 따라 심각한 불량문제(ill-posed problem)를 야기하여 부정확한 결과를 나타내기도 한다. 이의 해결을 위해 전처리 과정으로 평활화를 위한 여러 가지 mean filter를 사용하기도 한다. 그렇지만 원 자료가 근본적으로 복잡한 경우 위 과정으로 오히려 중요 정보가 소실될 수도 있다. 이에 본 논문에서는 먼저 전처리로서 흔히 사용되는 각종 평균필터 대신 손실을 최소화하면서 곡면의 부드러움(smoothness)을 유도할 수 있는 접평면 접근 방식을 이용하고, 아울러 대상 영상의 복잡도에 연동한 프랙탈 차원을 적용하여 보다 효과적으로 영상의 경계를 추출하고자 했다.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2000년도 종합학술발표회 논문집 Vol.10 No.1
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• pp.238-242
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• 2000

In this paper, the method for dielectric constant and less tangent measurements of microwave substrates using a microstrip line is presented. The two samples of an open-ended line and a short-ended tine are made and complex propagation constant is evaluated from the one-port scattering parameter measurements. This method has been automated fully using a personal computer and a vector network analyzer.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.303-306
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• 2001

Composite insulating materials used in outdoor high voltage equipment are required to have high electric performance because of the miniaturization. The frequence dependence of the permittivity and the loss tangent have important information. In this paper we describe the frequency dependence of the permittivity and the loss tangent for epoxy resin filled with silica and the influence of filler shape on the dielectric properties. The increment of tan $\delta$ in the low frequency region is caused by the increment of both of the electrical conductivity and the polarization due to the shape of filler and water sbsorbed in and near the interface between the fillers and resins. Result of charge current and discharge measure, electric conduction increased according to voltage.

• 대한안전경영과학회지
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• 제3권3호
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• pp.231-241
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• 2001

The epoxy resin materials used in outdoor high voltage equipments are required to have the high electric performance because of the miniaturization. The frequence dependence of the permittivity and the loss tangent have important information. In this paper we describe the frequency dependence of the permittivity and the loss tangent for epoxy resin filled with silica and the influence of filler shapes on the dielectric properties. The increment of tan $\delta$ in the low frequency region is caused by the increment of both the electrical conductivity and the polarization due to the shape of filler and the water absorbed in and near the interface between fillers and resins. The result of charge current and discharge measure, electric conduction is increased according to voltage.

• 한국전기전자재료학회논문지
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• 제26권9호
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• pp.656-661
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• 2013

In this study, the moisture content, charge discharge current, electrostatic capacity and dielectric loss tangent are measured for the specimen of bisphenol type epoxy resin which is mixed with squared amorphous silica filler and dipped in hot water of $50^{\circ}C$ for 169 days. The results of this study are listed below. The longer of deposition day, the charge and discharge current was increased. It is considered that the reason is because there was water attack through the squared silica surface. The longer of deposition day, the absorption rate of all specimens was increased. It found that the absorption rate reached saturated state after 100 days. The higher frequency and the longer of deposition day, the $tan{\delta}$ was decreased. Also, It found that the $tan{\delta}$ and electrostatic capacity of the specimen which is mixed with squared filler are greater.

• 전자공학회논문지D
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• 제34D권3호
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• pp.17-24
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• 1997

Broad-band RAM's (Radar absorbing materials) are designed by multi-layered lossy dielectrics. The depth, the relative permittivity and the loss tangent of each layer are optimized in order to meet the required reflective power over the specified frequency range using a genetic algorithm. The reflection coefficients are calculated by the continued fraction method. A new population model of the partial initialization method during iterations is applied for the multi-modal functions to enhance the performance of the genetic algorithm. The optimal RAN's are designed by setting the relative permittivity and the loss tangent of the dielectrics as a funtion of the frequency over 5~20GHz.

• 한국안전학회지
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• 제15권4호
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• pp.41-46
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• 2000

Silicone rubbers are elastomeric materials and organic copolymers, of which backbone is siloxane with high bonding strength. Silicone rubbers have been used as an power insulator because they are well weather proof, ozone proof and have excellent electric characteristics, thermal stability, cold resistance and low surface energy. Especially, it is known that they have very excellent characteristics at 200[$^{\circ}C$]. For this study, we made silicone rubbers as specimens and measured volume resistivity due to applied voltage and a variation of temperature 25[$^{\circ}C$] to 180[$^{\circ}C$]. Also we measured dielectric loss tangent due to applied voltage at temperature range 25[$^{\circ}C$] to 180[$^{\circ}C$] and frequency range 20[Hz] to 1${\times}10^6$[Hz].

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.444-447
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• 2003

All objects with some temperature above absolute zero radiate in the infrared. The intensity of the infrared radiated from a object defends on the condition and temperature on the surface of the one. The present, these techniques are frequently adopted into diagnosis for electricity equipments. Simply, however, the applied techniques are passive thermal testing for the detection of loosened terminals and overcurrent. In this paper, a infrared thermal imager was applied to high voltage windings of cast resin transformers, and the accumulated value of the result temperatures was used for evaluating remained lifetime of them. At each aging level, dielectric loss tangent test was carried out. The results offered capabilities for deciding the condition of the transformers suffering difficulties to diagnose.

• 한국전기전자재료학회논문지
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• 제18권11호
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• pp.1038-1042
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• 2005

We have investigated dielectric properties depending on bias voltage in organic light-emitting diodes using 8-hydroxyquinoline aluminum $(Alq_3)$ as an electron transport and emissive material. We analyzed the dielectric properties of organic light-emitting diodes using impedance of characteristics. Impedance characteristics was measured complex impedance Z and phase $\theta$ in the frequency range of 40 Hz to $10^8$ Hz. We obtained complex electrical conductivity, dielectric constant, and loss tangent $(tan\delta)$ of the device at room temperature. From these analyses, we are able to interpret a conduction mechanism and dielectric properties contributed by an interfacial and orientational polarization.

• Elastomers and Composites
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• 제25권2호
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• pp.97-102
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• 1990

국내에서 생산, 혹은 수입 시판되고 있는 11종류의 EPDM과 1종의 EPM고무에 대한 선형점탄성적 성질을 RDS로 측정하였다. 측정은 $210^{\circ}C$에서 등온적으로 행하였으며. 이들 고무의 복합점도, 저장탄성계수, 손실탄성계수, 손실 tangent 및 완화스팩트럼 data는 고무 블렌딩이나, 복합화과정에서 중요한 자료로 이용될 것으로 믿는다.