• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.29 no.10
• /
• pp.613-619
• /
• 2016

The aim of this study is to improve of dielectric properties using epoxy/nano alumina composites with adding glycerol diglycidyl ether (GDE:1,2 g). This paper deals with the effects of dielectric properties(${\epsilon}^{\prime}_r$ and $tan{\delta}$) for epoxy/nano alumina contents (1,3 phr) and GDE addition (1,2 g)composites. 5 kinds specimen were prepared with containing epoxy resins, epoxy nano alumina composites. Average particle size of nano used were 30 nm. The nano alumina used were gamma phase particles of spherical shape. The suppression of epoxy chain motion by addition of nano alumina+GDE decreased dielectric loss and relative permittivity magnitude.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.12
• /
• pp.2166-2172
• /
• 2007

In this study a low-signal equivalent circuit based on the Double Schottky Barrier model is proposed for ZnO-based varistor. Since pin-lead inductance and stray capacitance are considered in pin-lead type ZnO varistor these inductance and capacitance could be removed from the experimental dielectric data of the varistor. According to the equivalent circuit simulation results the higher the varistor-voltage of varistor sample the capacitance of dielectric layer is larger, and the capacitances of semiconducting layer and depletion layer are smaller, while the parallel resistances of semiconducting layer and depletion layer are more larger values. Spectra of the dielectric loss factor $tan{\delta}$ show 2 peaks in low frequency and high frequency regions respectively. The low-frequency peak is due to the relaxation by deep donors and the high-frequency peak is due to the relaxation by shallow donors. Above results are well consistent with the theoretical mechanism of ZnO varistor.

• Proceedings of the KIEE Conference
• /
• 2003.07c
• /
• pp.1418-1420
• /
• 2003

In this study capacitance and dielectric loss tan${\delta}$were measured with frequency changes for commercial $Z_nO$ varistors with pin-type leads and equivalent circuit simulation was proposed. The leakage inductance in pin leads and the stray caoacitance could be seperated from the dielectric characteristics of $Z_nO$ varistors by the simulation of equivalent circuit. The equivalent circuit model considered semiconduction layer, dielectric layer and depletion layer as the grain boundary structure of varistor is well fitted to the observed data.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.7 no.2
• /
• pp.51-56
• /
• 1993

In this paper the affect an inorganic filler and a filling up water absorption in epoxy composite material was represented. The results are summarized as follows; 1. In the case of Sample 1, Sample 2 and a fillng up water absorption, the frequency depenence of ${\varepsilon}_\tau$ shows the straight characteristic under $140^{\circ}C$. 2. Between lOOHz and 3kHz, the frequency dependency of $tan{\delta}$ is dominated by the loss of a dipole relaxation than the conductive loss for movement of a career. The effect of water absorption, is increased as the frequency is decreased.

• Proceedings of the KIEE Conference
• /
• 1997.07d
• /
• pp.1465-1468
• /
• 1997

In this study we investigated the aging characteristic such as leakage current, dielectric loss, contact angle, of EPDM for outdoor use by thermal treatment. And also observed the color change of surface, changing of chemical ingredient of the marterials by optical microscope. SEMI, FTIR and EDX at the section and surface. The test result show that leakage current is increased with thermal aging time. contact angle and dielectric loss is slightly decreased. Moreover, micro-void or crack in bulk is severely increased with aging time. However, the result affect to the tan $\delta$ at bulk of EPDM. It seems that carrier sources are removed by degassing with heat treatment.

• Proceedings of the KIEE Conference
• /
• 1997.07d
• /
• pp.1417-1419
• /
• 1997

In this paper, the dielectric properties is made researches by the dose of electron beam in order to investigate the electrical properties for transformer oils due to electron beam irradiation. To measure the dielectric loss of irradiated specimen, the liquid electrode of coaxial cylindrical shape is used, and its geometric capacitance is 16 [pF]. And the dielectric dissipation factor, $tan{\delta}$, is measured by using the Video Bridge 2150. The thermal static oven with an automatic temperature controller is used so as to apply specific temperature to specimen. This experiments for measuring the dielectric loss is performed at $20{\sim}120[^{\circ}C]$ in temperature range, $30{\sim}1.5{\times}10^5[Hz]$ in frequency and $300{\sim}500[mV]$ in voltage.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.55 no.8
• /
• pp.411-416
• /
• 2006

A new method on the evaluation of insulation oil was proposed. Terahertz time-domain spectroscopy (THz-TDS) was applied to investigate the properties of the insulating oil. For the diagnostics of oil degradation, three kinds of oils have been analyzed by THz-TDS. The degraded oil showed different optical and electrical constants compared with a new one. Generally, the power absorption coefficient, the refractive index, the dielectric constant and loss $tan{\delta}$ of the oil increase as the aging of insulating oil proceed. And the characteristics of two kind of insulation oil, 1-4 and 7-4, was compared in terahertz spectral region. Difference in refractive index and complex dielectric constant has been observed between the samples. The results of this study suggest that THz-TDS is a promising new means for evaluating degradation and identification of insulating oil.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.705-708
• /
• 2001

The effect of grinding on the synthesis of LaAO$_3$ceramics was investigated. The mixture ground by plantary ball mill showed 70nm particle size (wet ball mill or unground=0.5 $\mu$m). Monophase LaAlO$_3$powders were formed when ground samples were heated at 100$0^{\circ}C$, however unground samples required temperatures above 130$0^{\circ}C$. Density of the ground samples sintered at 140$0^{\circ}C$ showed 98.3% of theoretical density (unground=93.5% at 150$0^{\circ}C$). Dielectric constant of the ground samples($\varepsilon$r=22.4) showed higher values than that of the unground samples($\varepsilon$r=20.32). Temperature coefficient of capacitance($\tau$$_{c}$) and dielectric loss (tan$\delta$) of the ground samples were similar to those of unground samples.s.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.11a
• /
• pp.490-491
• /
• 2007

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

• Journal of the Korean Ceramic Society
• /
• v.39 no.8
• /
• pp.742-749
• /
• 2002

The PZT thin films werre deposited on Pt/Ti/$SiO_2$/Si substrate by R. F. magnetron sputtering with $Pb_{1.1}Zr_{0.53}Ti_{0.47}O_3$ target. When interlayers(PbO, $TiO_2$, PbO/$TiO_2$) were inserted between PZT and Pt, the crystallization of the PZT thin films was considerably improved and the processing temperature was lowered. Compared to the pure PZT thin films, dielectric constant, dielectric loss and polarization properties of PZT thin films with interlayers were considerably improved. From XPS depth profile analysis, it was confirmed that PZT thin films and interlayers existed independently. In particular, PZT thin films deposited on interlayer(PbO/$TiO_2$) showed the best dielectric property (${\varepsilon}_r$=414.94, tan${\delta}$=0.0241, Pr=22${\mu}C/cm^2$).