• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.52-56
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• 2001

Experiments of 2 type on insulating compounds accomplished to change PVC using in URD(Underground) power cable jacketing. one was DB (Dielectric Breakdown) test on the pure base resins and the others were WVT(Water Vapor Transmission) test on the compounds which contained C/B(Carbon Black), anti-oxidant to base resin. a kind of specimens made by pressing to resin of pellet or lump form was HDPE(High Density Polyethylene), MDPE(Medium Density Polyehylene), LDPE(Low Density Polyethylene), LLDPE(Linear Low Density Polyethylene), PVC (Polyvinyl Chloride). As a results of AC DB and WVT test, we saw that strength of Insulation was HDPE > LLDPE ≒ MDPE > LDPE and WVT ratio was HDPE < LLDPE < MDPE < LLDPE ≒ LDPE${\ll}$PVC. WVT of PVC using for jacket showed characteristic 15 times more than MDPE or LLDPE. Therefore, to development of watertightness cable, our works present need of Changing in insulating materials

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.941-943
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• 1999

In this paper, the AC breakdown properties to investigate the electrical properties of gate oxide layer in MOSFET was studied. 5 inch arsenic epi-wafer is selected as an experimental specimen, the power MOSFET of a general MOS structure was made. In order to analyze the physical properties of the specimen, the SIMS(secondary ion mass spectroscopy) was used. As the experimental condition, the experiment al of the AC breakdown characteristics was performed when the thickness of gate oxide layer is $600[\AA]$ and $800[\AA]$, the resistivity is $1.2[\Omega{\cdot}cm]$, $1.5[\Omega{\cdot}cm]$ and $1.8[\Omega{\cdot}cm]$, and the diffusion time is 110[min] and 150[min] in temperature $30[^{\circ}C]{\sim}100[^{\circ}C]$. From the analysis result of the SIMS spectrum, it is confirmed that the dielectric strength is decreased by contribution of the impurities ad dition as increasing in thickness of the gate oxide layer in MOSFET.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.11
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• pp.41-46
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• 2015

This study was conducted to discover a substitute of $SF_6$ gas. $SF_6$ gas is widely used across the industries. Thanks to superior electrical properties, in particular, it has been commonly used in electrical industry. However, there have been a lot of studies on its serious effect on global warming. As a substitute of this synthetic gas, a mixture of dry air and $N_2/O_2$ was chosen in this study. In case of $N_2/O_2$, dielectric strength differs depending on the mixing ratio. This study examined dielectric breakdown and flashover after adjusting oxygen percentage in the dry air. This test was conducted in a quasi-uniform electric field depending on pressure, oxygen concentration and gas mixtures. The test results found that dielectric voltage and flashover voltage were the highest at a certain oxygen concentration. It is the results of this photoionization and electron attachment of oxygen.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.4
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• pp.589-594
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• 1997

This study was performed to clarify the effect of anesthesia killing and non-bleeding on the physicochemical and rheological properties of plaice, Paralichthys olivaceus muscle at early period after death. Live plaice was killed by the two different methods: spiking at the brain instantly with bleeding and dipping In seawater containing anesthetic (2,000 ppm ethyl-aminobenzoate) for 10 min without bleeding. These samples were stored at $0^{\circ}C$ and used in checking rigor-mortis, ATP breakdown, the content of ATP and its related compounds, breaking strength, and lactate accumulation through storage. The rigor-mortis, ATP breakdown, and lactate accumulation was faster in samples killed by spiking than in samples killed by anesthesia. ATP in samples killed by anesthetic showed little breakdown until 22.5 hrs, but it was decomposed completely after 30 hrs storage. Breaking strength of samples killed by spiking at the brain instantly with bleeding decreased steadily and showed the maximum value over 10 hrs $(2207.3{\pm}60.2g)$. However, in case of the dipping fresh flesh without bleeding in seawater containing anesthetic, the value and time reached around the maximum breaking strength were $2147.8{\pm}29.0g$ and 13 hrs respectively, but it maintained constantly until 20 hrs passed. From these results, it could be suggested that anesthesia killing and non-bleeding is more effective in maintaining firmness of fresh plaice muscle than spiking killing with bleeding at the early period after death.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.1
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• pp.23-30
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• 1995

This study was undertaken to clarify the effects of electrical stimulation on physicochemical and rheological properties of the plaice (Paralichthys olivaceus) muscle at early period after death. The plaices were electrically stimulated in seawater bath (110V/60Hz) for 15sec., 35sec., and 60sec. and killed instantly with spiking at the head. Killed samples were stored at $5^{\circ}C$, and the changes in rigor index, ATP breakdown, lactate accumulation, and breaking strength of muscle through storage were investigated. Electrical stimulation effectively accelerated rigor-mortis, lactate accumulation , and ATP breakdown. As the time of electrical stimulation was lengthened, the onset of rigor-mortis of all samples were accelerated Just after killing, and the amount of lactate was rapidly increased, But, significant differences were not observed in variance of rigor-mortis and lactate concentration. Electrically stimulated plaices showed decreasing in ATP to $4.58{\mu}mole/g$ for 15sec., $4.13{\mu}mole/g$ for 35sec., and $2.39{\mu}mole/g$ for 60sec. samples as compared with $5.5{\mu}mole/g$ of unstimulated samples. As the time of electrical stimulation was lengthened, ATP in samples were decomposed more rapidly. The rate constant of ATP breakdown were $0.244hr^{-1}$ for 15sec., $0.358hr^{-1}$ for 35sec., and $0.479hr^{-1}$ for 60sec.. The level of breaking strength in muscle of the plaice was $1050.30\pm50.23g$ immediately after killing. Values of breaking strength in samples electrically stimulated for 35sec. increased rapidly just after killing among all samples. However, the breaking strength was not increased through the whole storage time in samples stimulated for 60sec.. The value and time roaching to the maximum breaking strength for each samples stimulated electrically for 15, 35 and 60 second were $1264.43\pm35.76g$ and 2hr, $1357.68\pm22.50g$ and Ohr, and $1012.18\pm57.36g$ and Ohr. Breaking strength in all samples electrically stimulated decreased significantly (P<0.05) after reaching the maximum values.

• Transactions on Electrical and Electronic Materials
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• v.13 no.2
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• pp.85-88
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• 2012

Studies on the effects of layered silicate content on the AC electrical treeing and breakdown behaviors of epoxy/layered silicate nanocomposites were carried out in needle-plate electrode geometry. Wide-angle X-ray diffraction (WAXD) analysis and transmission electron microscopy (TEM) observation showed that 1 wt% of the multilayered silicate was fully exfoliated into nano-sized monolayers in the epoxy matrix however, over 3 wt% of the silicate was in an intercalated state. When 1 wt% layered silicates were incorporated, an electrical tree was initiated in 439 min and propagated at a speed of 2.3 ${\mu}m$/min after applying 781.4 kV/mm, representing a decreased in starting initiation time by a factor of 11.0 and increase in propagation speed by a factor 8.2 in comparison with neat epoxy resin. These values were in great decline after the layered silicate content was increased to 3wt% which implies that the exfoliated silicate blocked the tree initiation and propagation processes effectively. However the effect was largely decreased in the intercalated state.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.840-845
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• 2017

In this paper, in order to investigate the lifetime of oil-paper insulation, specimens were artificially aged with thermal and electrical multiple stresses. Accelerated ageing factors and equivalent operating years for each aging temperatures were derived from results of tensile strengths for the aged paper specimens. Also, the evaluation for the multi-stress aged specimens were carried out through the measurement of impulse breakdown voltage at high temperature of $85^{\circ}C$. The lifetimes of the oil-paper insulations were calculated with the value of 66.7 for 1.0 mm thickness specimens and 69.7 for 1.25 mm thickness specimens throughout the analysis of impulse BD voltages using equivalent operating years, which means that dielectric strengths would not be severely decreased until the mechanical lifetime limit. Therefore, for the lifetime evaluation of the oil-paper insulation, thermal aging would be considered as a dominant factor whereas electrical degradation would be less effective.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.219-220
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• 2013

The phenomenology of liquid breakdown has been an area of interest for many years but is still not fully understood. Moreover, it was known that the behavior of magnetic nanoparticles in transformer oil could affect the dielectric breakdown voltage positively or negatively. In this study, we have imaged the magnetic nanoparticles in a transformer oil in-situ using an optical microscopic set-up and a microchannel according to the electric and magnetic fields applied. And we have calculated numerically dielectrophoresis and magnetophoresis forces, which must be the driving mechanisms to move magnetic nanoparticles in the fluid. It was found that when the electric field is applied the magnetic nanoparticles in the fluid experience an electrical force directed toward the place of maximum electric field strength. And when the external magnetic field is applied, the magnetic nanoparticles form long chains oriented along the direction of the field.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.113-114
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• 2008

The purpose of this paper is to analyze AC Breakdown of solid/air composite insulation depending on the thickness and the pressure of dry air for eco-friendly insulation. SF6 gas has been widely used in electric equipment as gas insulation because of high dielectric strength and arc extinguishing performance. However, because SF6 gas is one of the green house effect gases, alternative insulation such as SF6 mixture, extremely low temperature gas, vacuum, liquid and solid insulating are being investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.54-57
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• 1997

The electrical properties such as space charge accumulation, dielectric breakdown and water treeing of acrylic acid-grafted polyethylene (PE-g-AA) and n-butyl acrylate-grafted polyethylene (PE-g-nBA) were investigated. In PE-g-AA, heterocharge founded in LDPE decreased with the increase of AA graft ratio and changed to the homocharge formation above 0.lwt% due to the introduction of carbonyls. Conduction currents decreased with the increase of AA graft ratio. AC breakdown strength increased and water treeing length decreased with the increase of graft ratio in PE-g-AA and PE-g-nBA.