• Journal of Electrical Engineering and Technology
• /
• v.13 no.3
• /
• pp.1355-1362
• /
• 2018

In order to obtain a better understanding of the ageing process of the field composite insulators, it is necessary to explore a quantitative-valuation method for the aging state evaluation. And the linear relationship between volume resistivity and temperature is proposed. In this paper, the composite insulators with different lengths of operating lives from two manufacturers were tested. The relationship between trap characteristics and volume resistivity-temperature characteristics were analyzed based on Thermal Stimulated Current (TSC), volume resistivity-temperature test, Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Furthermore, the application of trap characteristics in the quantitative evaluation of aging state of composite insulators was discussed. The results showed that there was a general negative correlation between the relative variation ratio of trap charges and the volume resistivity-temperature characteristics. Meanwhile, the physicochemical properties would change with the aging time, which would result in the increasing of electron traps. Combined with the TSC and volume resistivity test results, the trap characteristic thresholds which indicated the serious age of the composite insulators had been proposed.

• Journal of Applied Biological Chemistry
• /
• v.62 no.1
• /
• pp.101-107
• /
• 2019

The objectives of this study were to evaluate the anti-aging effects and investigate the effect of simulated gastrointestinal (GI) digestion on the anti-aging properties and intestinal permeation of the potential fish collagen hydrolysates (FCH). Therefore, procollagen synthesis, matrix metalloproteinase-1 (MMP-1) production, and Caco-2 cell permeability were analyzed before and after in vitro digestion for FCHs, low-molecular weight fractions (<1 kDa), and high molecular weight fractions (>1 kDa). After being subjected to GI digestion, the level of MMP-1 inhibition was maintained, although the procollagen production was significantly (>20%) lower with all samples. Also, the digested FCHs and their <1 kDa fraction yielded 9.1 and 13.8% increased peptide transport, respectively, compared to undigested samples. Based on the effective intestinal permeation and high digestive enzyme stability, the <1 kDa fraction of FCHs is a potential bioactive material suitable for anti-aging applications in the food and cosmetics industries.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.11a
• /
• pp.549-550
• /
• 2008

• Proceedings of the KIEE Conference
• /
• 1990.11a
• /
• pp.132-135
• /
• 1990

This paper presents prediction of insulation lifetime in stress. Essentially, Epoxy resin, when it was subjected to different types of aging condition, produced to varieties of electrical properties and lifetime using spectroscopy and breakdown test. The relationships between the structural and electrical changes of aged epoxy were Investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1993.05a
• /
• pp.52-54
• /
• 1993

A new type of semiconductor fuse-link with fuse elements deposited on ceramic substrate introduced. The construction and aging property of this fuse-link, as well as the test circuitry built especially for the development of this fuse-link explained below.

• Fibers and Polymers
• /
• v.2 no.4
• /
• pp.171-177
• /
• 2001

Change of tensile properties, electrical conductivity and microwave shielding of electrochemically synthesized polypyrrole films with time are presented. Highly doped films had good electrical stability, retaining high microwave reflectivity throughout the aging period. Lightly doped films were less stable and partially reflective and absorptive of microwaves. FT-IR spectral observations revealed a progressive increase in intensity of an unsaturated conjugated carbonyl peak, which was not observed in the highly doped films, suggesting that the concentration of the dopant had an influence on mechanism of degradation of conductivity.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.8 s.179
• /
• pp.2032-2041
• /
• 2000

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.05a
• /
• pp.522-525
• /
• 1999

The electrical characteristics of 3 year field-aged polymer insulators which dismounted from five regions were investigated. There was a little difference in PD inception voltage depending on the manufacturers and the regions. The results between PD and SD showed a close relation. There were no significant changes in electrical properties. So, it can be considered that the field-aged insulators are sound for the present.

• Journal of the Korean Society for Heat Treatment
• /
• v.8 no.4
• /
• pp.245-254
• /
• 1995

The purpose of this study was to examine the effects of low melting point phase(LMPP) on mechanical properties in the Al-Cu-Li-X(In, Be) alloys. This study was performed by the differential scanning calorimetry(DSC), the transmission electron microscope(TEM), hardness test, tensile test and notch tensile test. The shape of LMPP in the specimens homogenized at $570^{\circ}C$ was film type due to remelting at grain boundary during homogenization. Low melting point phases had no effects on mechanical properties in the aging treated materials, because the density of LMPPs was low. Mechanical properties of the aging treated materials were affected by the density of matrix precipitation phases and grain sizes. For the In or In, Be added Al-Cu-Li alloys, the optimum solution treatment temperature was $550^{\circ}C$. The strength of Al-Cu-Li-In-Be $T_6$ treated alloy was higher than that of 2090-$T_8$ alloy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.19 no.12
• /
• pp.1085-1091
• /
• 2006

The microstructure, electrical properties, and its stability of (Pr, Co, Cr, La)-doped ZnO varistors were investigated at different sintering temperatures in the range of $1230{\sim}1300^{\circ}C$. As the sintering temperature increased, the sintered density increased from 5.50 to $5.77g/cm^3$, the varistor voltage decreased from 777.9 to 108.0 V/mm, the nonlinear coefficient decreased from 77.0 to 7.1, and the leakage current increased from $0.4{\mu}A\;to\;50.6{\mu}A$. On the other hand, the donor concentration increased from $0.90{\times}10^{18}\;to\;2.59{\times}10^{18}/cm^3$ and the barrier height decreased from 1.89 to 0.69 eV with increasing temperature. The stability of nonlinear electrical properties was obtained from sintering temperature of $1260^{\circ}C$. The varistors sintered at $1260^{\circ}C$ marked the high electrical stability, with $%{\Delta}V_{1mA}=+1.9%,\;%{\Delta}a=10.6%,\;and\;%{\Delta}I_L=+20%$ for DC accelerated aging stress state of $0.95V_{1mA}/150^{\circ}C/24h$.