• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.6
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• pp.251-255
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• 2007

We made $(1-x)BCB-xBNT(BaNd_2Ti_4O_{12})$ (x=20, 30, 40, 50 vol%) composite thick film with a high dielectric constant and low loss by the hand casting method. Dielectric constant and dielectric loss of prepared thick film are measured at 1MHz and curing behavior of the film are observed through thermal analysis such as DSC. We investigated the effect of contents of BNT filler and curing behavior of film on dielectric properties of BCB-BNT composite. Dielectric constant increased with increasing BNT filler from 20 to 50 vol% and dielectric loss ($tan{\delta}$) decreased with increasing BNT filler. Dielectric constant and loss ($tan{\delta}$) of composite material was not nearly dependent on the curing behavior. But as a result of TCC (Temperature Characteristics of Coefficient) decreased with increasing the curing temperature, we confirmed that the curing of these composite system is most stable above $250^{\circ}C$.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.304-306
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• 1987

The dielectric loss ($tan{\delta}$) and the Capacitance (C) of the PPMKA(plasma-polymerized methyl metacrylate) films were measured in the frequency range of 1KHz - 5MHz at $25^{\circ}C$. The effects of the oxidation and the heating and the plasma treatment for $tan{\delta}$ and C of PMMA were investigated. Dielectric loss of PPMMA films was inceased with the oxidized products like CO and OH. As condidates for their origin the existence of low molecula moieties and free radicals in the PPMMA, and the crosslinking made by the heating and plasma treatment have been considered.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.169-172
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• 2000

In this paper, we evaluated the mechanical and dielectric properties of LDPE depend on $Co_{60}$${\gamma}$-irradiation doses. The chemical analyses for FT-IR, gel content, the mechanical properties for elongation at break and the dielectric parameters for permittivity, tan$\delta$ were discussed as a function of irradiation doses. Test result presented that elongation at break of irradiated LDPE was inversely proportional to gel content. For dielectric analyses, permittivity showed a salient characteristic for various irradiation doses, it was related to polar groups caused radiation degradation and tan$\delta$ of irradiated LDPE increased with irradiation doses.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.193-196
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• 2001

XLPE is occasionally happened to deteriorate cable insulation characteristics. It is happened to do a breakdown state by the degradation of electrical characteristic and electrical breakdown strength. I prepared TR-XLPE (Tree-Retardant XLPE) as adding various additives to prevent its states. Various additives are treeing retardants, anti-oxidants. Treeing retardants three kinds of aromatic compounds as adding each additive. Anti-oxidants use quinone compound and cresol compound as adding each additive. In order to observe each electrical characteristics, I measured breakdown strength, relative dielectric constant$({\varepsilon}_r)$, dielectric loss tangent$(tan{\delta})$. TR-XLPE specimens as adding treeing retardants and anti-oxidants enhance breakdown strength, ${\varepsilon}_r$, $tan{\delta}$ than pure XLPE.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.292-293
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• 2006

We have Investigated dielectric properties depending on bias voltage in organic lightemitting 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 characteristics measurement by the auto-balancing bridge technique and equivalent cirrcuit of ITO/$Alq_3$/Al. 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.293-294
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• 2005

We have investigated dielectric properties depending on frequency 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.04a
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• pp.74-75
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• 2006

We have investigated dielectric properties depending on temperature 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 characteristics of impedance. he Impedance characteristics was measured complex impedance Z and phase $\theta$ in the temperature range of 10 K to 300 K. 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.12
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• pp.847-851
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• 2014

The characteristics of dielectric constant and $tan{\delta}$ of low viscosity silicone oils with changing degree of polymerization were investigated. The result shows dipole loss mechanism at low temperature range. The dielectric loss in the range of low frequencies are predominantly of ionic nature with temperature increase. The peak of dielectric loss is the detrapping of the electrons which is were trapped in the localized level of the silicone oils at the frequency of 30 kHz. The increase of ionic conduction is attributed to the presence of ionizable oxidation products and their increased dissociation feature. The activation energy ${\Delta}H$ and dipole moment ${\mu}_d$ were increased whit increasing degree of polymerization.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.10
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• pp.1780-1785
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• 2016

This paper presents few case studies of state diagnosis of XLPE cables using very low frequency techniques. The power cables of 22.9kV which have installation fault were assessed using VLF technique in addition to other techniques like insulation resistance and DC voltage withstand test. From the experimental results, The dielectric loss($tan{\delta}$) values of degradation of the cable(joint, knife, needle) at $U_0$ were 5.839, 5.526 and 6.251, respectively and all values were "further study advised". VLF PD measurement was also found defective portion. These method was effective in defect to fault in the degradation of the cable. However, the breakdown did not occur in the degradation of the cable because of properties of XLPE insulation. Few case studies of using VLF $tan{\delta}$ diagnosis for fault are measured and analyzed. The $tan{\delta}$ values at $U_0$ were "further study advised" or "action required".

• Elastomers and Composites
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• v.18 no.2
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• pp.51-59
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• 1983

The dielectric properties of polymers are very important when investigating the molecular structure of polymers. The characteristics of the dielectric absorption in vulcanized natural rubber were studied in frequency ranging from 10[KHz] to 32[MHz] at the temperature of 25[$^{\circ}C$]. As a result of the study, it has been confirmed that natural rubber vulcanized below 4phr leads to two kinds of dielectric losses due to the interfacial polarization and the dipole polarization by sulfur, and of above 7[%] was only a loss due to the dipole polarization by sulfur. Futhermore, the dielectric loss maximum $tan{\delta}$ spectrum, removed to the low frequency in accordance with increasing sulfur, depends greatly on sulfur. The volume resistivity of $10^{7}{\sim}10^{11}[{\Omega}{\cdot}cm}]$, regardless of whether the crosslinking of rubber is weakened by sulfur, was observed.