Studies on a SF_{6}-mixture and -alternative gas has been in progress to reduce the use of SF_{6} gas as an insulation material of GIS (gas insulated switchgears). In this paper, we dealt with PD (partial discharge) characteristics in pure SF_{6} and N_{2}, and their mixtures on aspects of insulation design and risk assessment for GIS. A POC (protrusion on conductor) and a POE (protrusion on enclosure) as the major defects were fabricated to simulate PD. We analyzed the DIV (discharge inception voltage), DEV (discharge extinction voltage), pulse magnitude, counts and phase distribution of PD pulse in SF_{6}-N_{2} mixtures (SF_{6} 100%, SF_{6} 80%-N_{2} 20%, SF_{6} 50%-N_{2} 50%, SF_{6} 20%-N_{2} 80%, and N_{2} 100%) according to the IEC60270. The DIV, DEV as well as magnitude of PD pulse decreased on the POC as increase of N_{2} ratio. For the POE, the DIV and DEV in N_{2} ratio below 50% were the same voltages as those in SF_{6} 100%. In this experiment, SF_{6} 80%-N_{2} 20% mixture could be considered with the equivalent insulation performance to a GIS.

TiNOx multi-layer thin films on aluminum substrates were prepared by DC reactive magnetron sputtering method. 4 multi-layers of TiO2/TiNOx(LMVF)/TiNOx(HMVF)/Ti/substrate have been prepared with ratio of Ar and (N2+O2) gas mixture. TiO2 of top layer is anti-reflection layer on double TiNOx(LMVF)/TiNOx(HMVF) layers and Ti metal of infrared reflection layer. In this study, thecrystallinity and surface properties of TiNOx thin films were estimated by X-ray diffraction(XRD) and field emission scanning electron microscopy(FE-SEM), respectively. The grain size of TiNOx thin films shows to increase with increasing sputtering power. The composition of thin films has been investigated using electron probe microanalysis(EPMA). The optical properties with wavelength spectrum were recorded by UV-Vis-NIR spectrophotometry at a range of 200∼1,500 nm. The TiNOx multi-layer films show the excellent optical performance beyond 9% of reflectance in those ranges wavelength.

AlNO multi-layer thin films on aluminum substrates were prepared by DC reactive magnetron sputtering method. Al2O3/AlNO(LMVF)/AlNO(HMVF)/Al/substrate of 4 multi-layer has been prepared in an Ar and (N2+O2) gas mixture, and Al2O3 of top layer is anti-reflection layer on double AlNO(LMVF)/AlNO(HMVF) layers and Al metal of infrared reflection layer. In this study, the roughness and surface properties of AlNO thin films were estimated by field emission scanning electron microscopy(FE-SEM). The grain size of AlNO thin films increased with increasing sputtering power. The composition of thin films has been systematically investigated using electron probe microanalysis(EPMA). The optical properties with wavelength spectrum were recorded by UV-Vis-NIR spectrophotometry at arange of 200～1,500 nm. The absorptance of AlNO films shows the increasing trend with swelling(N2+O2) gas mixture in HMVF and LMVF deposition. The excellent optical performance showed above98% of absorptance in visible wavelength region.

ZnO crystals with different morphologies were synthesized through a thermal evaporation of Zn-Mn mixtures in air. The morphology was dependant on the Mn content in Zn-Mn mixture. The morphology was changed from rod to tetrapod shape with decreasing Mn content in Zn-Mn mixture. There sult indicates that the concentration of Mn might be responsible for the different morphologies of ZnOcrystals. XRD spectra showed that the ZnO crystals had a hexagonal wurtzite crystal strutures. For all the samples, room temperature cathodoluminescence spectra showed a ultra-violet emission at 380 nm and a green emission at around 500 nm. However, the intensity ratio of ultra-violet emission to green emission was significantly different with the Mn content in the source material.

Tubular-shaped ZnO crystals were synthesized by thermal evaporation technique under air atmosphere. Mixture of Zn and Mg powder was used as the source material. The thermal evaporation and oxidation of Zn/Mg mixture were carried out for 1 hr at 1,000℃ and 1,200℃ under in air under atmospheric pressure. When only Zn powder was used as a source material, tetrapod-shaped ZnO crystals were synthesized. This provides that Mg played a key role in the formation of the tubular-shaped crystals. SEM images showed that the tubular-shaped ZnO crystals grew along [0001] direction. XRD spectrum revealed that the ZnO tubes had hexagonal wurtzite structure. Two emission peaks at 380 nm and 510 nm were observed in the room temperature cathodoluminescence spectrum.

In order to develop electrical insulation materials, epoxy-nanosilica-microsilica mixture composites (ENMC) was synthesized, and mechanical properties such as their tensile and flexural strength, and AC insulation breakdown strength were investigated. Properties of mechanical strength and AC insulation breakdown strength are analyzed as scale and shape parameter with respect to weibull plot. Their tensile and flexural strength, AC insulation breakdown strength were compared original epoxy or EMC to ENMC. The 4 phr nano-silica addition and the 65 wt% micron-silica mixture composite (ENMC) was found to have the highest tensile and flexural strength. In the tensile strength was improved 29%, and flexural strength was improved 60.9% higher than those of the original epoxy. In the insulation breakdown strength, ENMC_4 phr was improved 17% and ENMC_5 phr was improved 15.8% higher than those of the EMC.

In order to application for high voltage heavy electric equipments, epoxy/microsilica 60 wt%/nano layered silicate composites (EMNC_60) and epoxy/microsilica 65 wt%/nano layered silicate composites (EMNC_65) respectively was synthesized by our electric field dispersion method and the result was obtained completely dispersion state. Thermal properties such as glass transition temperature (Tg) and thermal expansion coefficient, and DMA characteristics were studied, and mechanical properties such as tensile and flexural tests were performed. AC electrical insulation strength was also tested. The study on thermal property, EMNC_65 was better than EMNC_60 and mechanical ,electrical properties much improved EMNC_60 compared with EMNC_65.