• Journal of the Semiconductor & Display Technology
• /
• v.15 no.2
• /
• pp.26-31
• /
• 2016

The Townsend to glow discharge mode transition was investigated in the dielectric barrier discharge (DBD) helium plasma source which was powered by 20 kHz / $4.5 kV_{rms}$ high voltage at atmospheric pressure. The spatial profile of the electric field strength at each modes was measured by using the intensity ratio method of two helium emission lines (667.8 nm ($3^1D{\rightarrow}2^1P$) and 728.1 nm ($3^1S{\rightarrow}2^1P$)) and the Stark effect. ICCD images were analyzed with consideration for the electric field property. The Townsend discharge (TD) mode at the initial stage of breakdown has the light emission region located in the vicinity of the anode. The electric field of the light emitting region is close to the applied field in the system. Immediately, the light emitting region moves to the cathode and the discharge transits to the glow discharge (GD) mode. This mode transition can be understood with the ionization wave propagation. The electric field of the emitting region of GD near cathode is higher than that of TD near anode because of the cathode fall formation. This observation may apply to designing a DBD process system and to analysis of the process treatment results.

• Proceedings of the KIEE Conference
• /
• 1994.07b
• /
• pp.1536-1539
• /
• 1994

The influence due to metallic particle contaminated on spacer surface is remarkable in the decreasing of dielectric strength in $SF_6$ GIS. In relation with this problem, We studied, AC flash-over voltage characteristics and breakdown mechanism are investigated under metallic particle initiated condition in $SF_6$ gas by varying the particle position, particle shape with a plane-plane electrode. The main results arc as follows 1. The small amount of the metallic particle in the gap do not make flash-over voltage to be influence, but the significant decrease of th flash-overed voltage is result in case of the big and long size of the metallic paraticle. 2. Influence of the flash-over voltage are lowest in the mid and are highest in the electrode of metallic particle position. 3. In case of the initiated metallie particle, The more the pressure are high, the more the recluced ratio of flash-over voltage are high. 4. The metallic particle shape which results in the reduced flash-over voltage forced the critical pressure to move in to the region of low pressure. 5. The existance of the metallic particle on the upper electrode side and high pressure make the decreasing ratio of flash-over voltage bigger than that of the ground side electrode.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.64 no.12
• /
• pp.1724-1729
• /
• 2015

Chlorosulfonated polyethylene (CSPE) was not flooded seawater and flooded seawater & freshwater for 5 days, respectively, and these samples are referred to as BSF(before seawater flooding) and ASFF(after seawater & freshwater flooding), respectively. The apparent density, dissipation factor, relative permittivity, melting temperature, dielectric breakdown time and increased time of applied voltage are higher than those of BSF, but the insulating resistance, dielectric strength, percent elongation and glass transition temperature of ASFF are lower than those of BSF. The differential temperature of those is $0.026{\sim}0.028(^{\circ}C)$ after AC and DC voltage is applied to ASFF, respectively, and the differential temperature of those is $0.013{\sim}0.037(^{\circ}C)$ after AC and DC voltage is applied to BSF, respectively. In the case AC and DC voltage is applied to ASFF as well as BSF, the variations in temperature of AC voltage are higher than those of DC voltage. It is investigated that dielectric loss due to dissipation factor ($tan{\delta}$) is related to electric dipole conduction current. It is certain that the ionic (electron or hole) leakage current was increased by conducting ions such as $Na^+$, $Cl^-$, $Mg^{2+}$, $SO_4^{2-}$, $Ca^{2+}$ and $K^+$, those are related to cured atoms of O and S that relatively increased after seawater flooding.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2004.05a
• /
• pp.53-56
• /
• 2004

The a-Si:H TFT using ferroelectric of SrTi $O_3$as a gate insulator is fabricated on glass. Dielectric characteristics of ferroelectric are superior to $SiO_2$and S $i_3$ $N_4$. Ferroelctric increases on-current, decreases thresh old voltage of TFT and also improves breakdown characteristics. The a-SiN:H has optical band gap of 2.61 eV, refractive index of 1.8~2.0 and resistivity of 10$^{13}$ - 10$^{15}$ $\Omega$cm, respectively. Insulating characteristics of ferroelectrics are excellent because dielectric constant of ferroelectric is about 60~100 and breakdown strength is over 1MV/cm. TFT using ferroelectric has channel length of 8~20${\mu}{\textrm}{m}$ and channel width of 80~200${\mu}{\textrm}{m}$. And it shows that drain current is 3.4$mutextrm{A}$ at 20 gate voltage, $I_{on}$ / $I_{off}$ is a ratio of 10$^{5}$ - 10$^{8}$ and $V_{th}$ is 4~5 volts, respectively. In the case of TFT without ferroelectric, it indicates that the drain current is 1.5 $mutextrm{A}$ at 20 gate voltage and $V_{th}$ is 5~6 volts. With the improvement of the ferroelectric thin film properties, the performance of TFT using this ferroelectric has advanced as a gate insulator fabrication technology is realized.zed.d.

• Transactions on Electrical and Electronic Materials
• /
• v.18 no.4
• /
• pp.207-210
• /
• 2017

The suspension arrangement of insulators provides flexibility and assists in power transmission in transmission lines. The performance of the insulator string is strongly influenced by the environmental conditions to which it is exposed, its shape and the inherent material properties of suspension-type insulators. The suspension-type insulators are mostly made from glass, porcelain and ceramic material due to their high resistivity. Irregularity in charge distribution throughout the porcelain insulator may lead to accelerated aging and electrical breakdown. A very high and steep lightning impulse voltage may also cause breakdown of suspension-type insulators. We investigated various material characteristics such as alumina addition, surface morphology, x-ray diffraction pattern and relative density of suspension porcelain insulators manufactured in 1989 (36,000 lbs.), 1995 (36,000 lbs.) and 2001 (36,000 lbs.) by the KRI Company for use in 154 kV high power transmission lines. We compared the material characteristics of these porcelain insulators with that of the top-of-the-line porcelain insulators (36,000 lbs.) manufactured by the NGK Company in 2000. These suspension-type porcelain insulators were exposed to arc and flashover tests to examine their electrical and mechanical strength. It was noted that alumina addition (17 wt.%) for K-2001 was one of the major contributors to the enhancement of the performance of the porcelain insulators and to their ability to withstand very high current generation during the arc test. The porcelain insulators manufactured during 2001 also showed the highest relative density of 95.8% as compared to the other insulators manufactured in 1989 and 1995 respectively 94.2% and 91.5%. We also discuss reports of various failure modes of suspension-type porcelain insulators.

• Korean Journal of Materials Research
• /
• v.29 no.2
• /
• pp.73-78
• /
• 2019

Lead free $(Ba_{0.7}Ca_{0.3})TiO_3$ thick films with nano-sized grains are prepared using an aerosol deposition (AD) method at room temperature. The crystallinity of the AD thick films is enhanced by a post annealing process. Contrary to the sharp phase transition of bulk ceramics that has been reported, AD films show broad phase transition behaviors due to the nano-sized grains. The polarization-electric hysteresis loop of annealed AD film shows ferroelectric behaviors. With an increase in annealing temperature, the saturation polarization increases because of an increase in crystallinity. However, the remnant polarization and cohesive field are not affected by the annealing temperature. BCT AD thick films annealed at $700^{\circ}C/2h$ have an energy density of $1.84J/cm^3$ and a charge-discharge efficiency of 69.9 %, which is much higher than those of bulk ceramic with the same composition. The higher energy storage properties are likely due to the increase in the breakdown field from a large number of grain boundaries of nano-sized grains.

• Journal of the Korea Institute of Building Construction
• /
• v.21 no.3
• /
• pp.189-194
• /
• 2021

LIBS has been attracting attention as an analytical method capable of real-time measurement without sample preparation. In this study, a Lab. scale LIBS device was fabricated to examine the applicability and reproducibility of LIBS in the analysis of chloride contents in mortar. The existing analysis method and LIBS analysis were performed simultaneously on the mortar test specimen with the chloride content adjusted. Compared to the chloride content condition of the mortar, the XRF and Potentiometric Titration results also showed a similar trend. As a result of LIBS analysis, chlorine ions were detected at a wavelength of 837.59 nm according to the chloride content condition. In order to improve the precision in various concentration ranges, the LIBS signal amplification of about 50 times through the electric field enhancement was implemented. Through the verification of the aqueous solution-based reproducibility, a high correlation between the LIBS signal strength and the Cl concentration was confirmed, and the possibility of applying LIBS to the durability diagnosis of concrete damage by chloride was confirmed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.37 no.3
• /
• pp.286-291
• /
• 2024

Research on aged insulation of cables by stress is constantly being considered for reliable and stable power transmission of offshore wind farms. This study aimed to evaluate the insulation characteristic of aged XLPE (cross-linked polyethylene) insulation for application of offshore wind farms. In this study, The XLPE insulation of cable was set as various mechanical strains. The XLPE insulation is exposed to the mechanical stress below yield strain of 5%, 10%, and 20%. Aged samples were tested by using the method of AC BDV (alternative current breakdown voltage), tensile strength, elongation, and SEM (scanning electron microscope) to obtain insulation characteristics. The experimental results show that the dielectric breakdown of the sample with a strain 20% was 50% lower than the unaged sample; thereby, demonstrating that the mechanical strain that occurred in the submarine cables can weaken the insulation characteristics. Therefore, mechanical strain should be monitored when laying and operating submarine cables for offshore wind farms.

• Elastomers and Composites
• /
• v.40 no.3
• /
• pp.196-203
• /
• 2005

In this work, the engine oil resistant evaluation and breakdown analysis of room temperature vulcanizing silicone adhesives were performed through the surface properties, thermal stabilities, adhesive strength, and morphology measurements. As a result, the permeation of engine oil into adhesive specimens was carried out from surface to center in the specimens. And the oil content in the adhesive specimens was increased and the Si-O-Si bond of the adhesives was decomposed with increasing the aging time. The TGA results indicated that the thermal degradation was mainly occurred at under and surfaces of the specimens. The tensile strength, elongation, and adhesive strength of the adhesives were significantly decreased after the engine oil resistant tests, which could be attributed to the initial lose of adhesive properties resulting from the engine oil absorption and thermal aging. And the failure mode of the adhesive specimens was changed from cohesive failure to interfacial failure.

• Journal of the Microelectronics and Packaging Society
• /
• v.24 no.4
• /
• pp.39-46
• /
• 2017

This paper presents the fabrication of ceramic insulation layer on metallic heat spreading substrate, i.e. an insulated metal substrate, for planar type heater. Aluminum alloy substrate is preferred as a heat spreading panel due to its high thermal conductivity, machinability and the light weight for the planar type heater which is used at the thermal treatment process of semiconductor device and display component manufacturing. An insulating layer made of ceramic dielectric film that is stable at high temperature has to be coated on the metallic substrate to form a heating element circuit. Two technical issues are raised at the forming of ceramic insulation layer on the metallic substrate; one is delamination and crack between metal and ceramic interface due to their large differences in thermal expansion coefficient, and the other is electrical breakdown due to intrinsic weakness in dielectric or structural defects. In this work, to overcome those problem, selected metal oxide buffer layers were introduced between metal and ceramic layer for mechanical matching, enhancing the adhesion strength, and multi-coating method was applied to improve the film quality and the dielectric breakdown property.