• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.05e
• /
• pp.53-56
• /
• 2003

In this paper we investigated electrical properties for epoxy resin with improved mechanical property, elastomer epoxy. Investigated electrical properties are permittivity, tan $\delta$ and breakdown voltage strength(BDV). Permittivity and tan $\delta$ have dependancy on additive Quantity in general purpose epoxy resin. In particularly, those have very high values at low frequency and high temperature according to increasing component of elastomer. In case of BDV test, those materials have only a little difference due to increasing elastomer components. But in case of high quantities of elastomer, BDV has a difference. These results are represented that elastomer epoxy resin despite superior mechanical property needs many carefully thought as application electrical insulation.

• Proceedings of the KIEE Conference
• /
• 2008.09a
• /
• pp.207-210
• /
• 2008

In this paper, we researched the dielectric properties and voltage dependence on slice XLPE sheet from 22[kV] and 154[kV] power cable. We studied effects for impurities and water for semiconductor shield through a dielectric properties experiment to estimate performance of insulating materials in power cable. Capacitance and $tan{\delta}$ of 22[kV], 154[kV] were 53/43[pF] and $7.4{\times}10^{-4}$, $2.1510^{-4}$. In these results, the trend was increased with the increase of temperature. The tan6 of XLPE/semiconductor layer was increased as compared with that of XLPE. Dielectric properties reliability of tan6 was small. Also, To improve mean-life and reliability of power cable in this study, we have investigated chemical properties showing by changing the content of carbon black that is semiconductive additives for underground power transmission. Specimens were made of sheet form with the three of existing resins and the nine of specimens for measurement. Chemical properties of specimens was measured by FT-ATR (Fourier Transform Attenuated Total Reflectance). The condition of specimens was a solid sheet. We could observe functional group (C=O, carbonyl group) of specimens through FT-ATR. From these experimental result, the concentration of functional group (C=O) was high according to increasing the content of carbon black. We could know EEA was excellent more than other specimens from above experimental results.

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

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.14 no.3
• /
• pp.97-106
• /
• 2000

This paper proposes on-line based a deterioration diagnosis device for diagnosis pole transformers using tan$\delta$ and FFT(fast Fourier transform). We measured tan$\delta$ and temperature to diagnose pole transformer insulating oil, diagnostic results are processed by FFT. For measuring convenience, we use R/F(radio frequency) wireless data communication module operating by secondary voltage of pole transformer. We have voltage variation test and oil temperature variation test to prove usability of proposed diagnosis device. The result of this paper shows that the proposed device can be used as deterioration diagnosis device of pole transformers.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.12B
• /
• pp.1087-1098
• /
• 2006

This study is unlike common Input-Output Analysis in the point that both RAS and methods are applied to the dynamic Input-Output Model simultaneously. We have analyzed the propagation effects on the regional economy from the investment generated by u-City construction in Wha-sung and Dong-tan City. The main results of the study are as follows. The total induced effect on production according to u-City construction in Wha-sung and Dong-tan City is estimated about 2.9 times. On the other hand, u-City industry is appreciated as a industry which a forward linkage effect is very high while a backward linkage effect is not that high.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1993.11a
• /
• pp.80-84
• /
• 1993

In this research, we studied the variation of the dielectric loss absorption of the dielectric loss absorption of the sample according with the change to $\^$60/Co-${\gamma}$-ray irradiation dose of the influence of temperature and applied voltage. In order to investigate the effect of irradiation oriented polypropylene film, we have observed dissipation factor within the temperature range of 30∼130 [$^{\circ}C$] and voltage range of 100∼250$^{\circ}C$ [V]. As for the dependency of temperature by dissipation factor, the ${\alpha}$-peak which appears at high temperature increases accordingly to the increasement of irradiation dose which is contributed by the crystal region and moves towards the high temperature. The ${\beta}$-peak which appears at low temperature is origined from dipoles and molecular motions in the amorphous region. As for the dependency of voltage by tan$\delta$, at low temperature the peak of the tan$\delta$, at low temperature the peak of the tan$\delta$ shifts accordingly to the increasement of irradiation dose towards the high temperature region.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07a
• /
• pp.362-365
• /
• 2002

Hf thin films were deposited on bottom metal using a RF magnetron sputtering method followed by oxidation and annealing in O$_2$ and N$_2$ ambient, respectively. Various top metal electrodes (i.e., Al, Au, and Cu) were deposited by evaporation, and their roles on physical and electrical properties were investigated. Using the XRD, SEM and AFM techniques, we confirmed that the grain size of HfO$_2$ thin films enlarges as a function of oxidation temperature, increasing dielectric constant. However, other electrical properties (e.g., tan) deteriorateas a consequence. The dielectric constant and tan of HfO$_2$ thin films oxidized at 500 $^{\circ}C$ were 17-25 and 3${\times}$10-3 - 2x10-2, respectively, in the frequency range of 1 Hz to 1 MHz. The leakage current density was less than 1${\times}$10-8A/cm2 up to 0.7 MV/cm. In addition, electrical properties of HfO$_2$ thin films (e.g., the dielectric constant, leakage current and tan $\delta$) depend on top metal electrode. We showed that Al top metal electrode results in the best result.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.11a
• /
• pp.138-139
• /
• 2005

To measure electrical properties and viscoelasticity of semiconducting materials in power cable, we have investigated dielectric properties and modulus of EEA/acetylene black composite showed by changing the content of acetylene black. The permittivity from experimental result was increased, while tan6 was decreased by an increment of the content of acetylene black. The modulus of specimens was increased according to a increment of a acetylene black content. And modulus was rapidly decreased at the glass transition temperature. The tan$\delta$ of specimens was decreased according to a increment of a acetylene black content.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.05c
• /
• pp.1-5
• /
• 2001

This paper describes the electrical characteristics of Nomex paper employed as an insulating material of distribution transformers. The relative permittivities(dielectric constants) and $tan{\delta}$(dielectric dissipation factors) were measured as a dielectric characteristic and the partial discharge inception voltages(PDIVs) and breakdown voltages were also measured as an electrical strength characteristic of Nomex paper. As a result, the permittivity and $tan{\delta}$ of Nomex paper showed temperature and frequency dependency. Especially, the permittivity of 0.18mm Nomex paper was 2.4 according to the ASTM condition. And the PDIVs and breakdown voltages were, almost linearly increased with the thickness of Nomex paper and its electrical strength was better than conventional kraft paper.

• Polymer(Korea)
• /
• v.25 no.2
• /
• pp.233-239
• /
• 2001

The ethylene propylene diene terpolymer (EPDM) blends with acrylonitrile butadiene rubber (NBR) were prepared by mechanical mixing method. Mooney viscosity, cure behaviors, compression set and dynamic mechanical properties were subsequently examined. Dynamic characteristics of the entire blends determined from a Rheovibron generally showed two glass transitions (T'$_{g}$s), -43$^{\circ}C$ and -4$^{\circ}C$ for NBR and EPDM, respectively. The tan $\delta$ peak monotonically shifted toward the higher temperature with increasing NBR content. It was also found that the optimum cure time was significantly decreased with loading of NBR.