• 전기의세계
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• v.27 no.1
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• pp.45-48
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• 1978

A pressure dependence in the value of Es/p at a constant pd is observed in sulphur hexafluoride at pressures in excess of about one bar. This is explained in terms of the non-idealgas behavior of SF$_{6}$ which has a significant influence on the interpretation of electrical breakdown of this gas. The criterions for breakdown at low pressures and in the presence of rough electrodes are modified to allow this phenomeneon.n.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.6
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• pp.490-494
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• 2020

Sulphur hexafluoride (SF₆) is mostly used as a current-insulating medium in gas-insulated switchgears (GIS), owing to its excellent dielectric strength and arc-extinguishing performance. The global warming potential (GWP) of SF₆, however, is 23,900 times that of CO₂, and its life time in the atmosphere is 3,200 years. For these reasons, new eco-friendly gases to replace SF₆ are required. In this study, the partial discharge (PD) characteristics of green gas for grid (g³) and dry air (N₂/O₂) were analyzed to compare with those of SF₆. A PD electrode system was designed to simulate the protrusion defect in GISs and fabricated for experimentation. To compare the PD characteristics of each gas, the discharge inception voltage (DIV), discharge extinction voltage (DEV), discharge magnitude, discharge pulse number, and phase pattern were analyzed. Results from this study are expected to provide fundamental materials for the design of eco-friendly GISs.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.421-422
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• 2003

Greenhouse gases (GHGs) such as carbon dioxide ($CO_2$), methane (CH$_4$), nitrous oxide ($N_2$O), chlorofluorocarbons (CFCs), sulphur hexafluoride (SF$_{6}$), together with water vapour ($H_2O$) and ozone play an important role in determining the earth's climate. The primary cause of the enhancement of GHGs is the global use of fossil fuels to generate heat, power, and electricity for a growing world population, as well as the changes in the land use, especially for agriculture. In addition, biomass buring and biofuel emissions play major roles in the GHG emissions in the Asian region because they produce large amounts of carbon monoxide (CO), nonmethane volatile organic compounds(NMVOC), black carbon(BC) and other gases. (omitted)d)

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1999-2001
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• 2000

Impulse breakdown voltage characteristics of sulphur-hexafluoride/nitrogen ($SF_{6}-N_{2}$) mixtures were presented. The applied voltages were the positive and negative lightning impulse (1.2/44${\mu}s$) and oscillating impulse ($0.4{\mu}s$/2.08MHz) voltages. The predischarge current was observed to clarify the breakdown mechanism. The electrode system was consisted of plane to plane configuration with a needle-shaped protrusion whose length and diameter are 10mm and 1mm. The measurements were carried out at the gas pressure of mixtures up to 0.5MPa with nitrogen concentrations varying from 5 to 20%. The electrical breakdown in $SF_{6}-N_{2}$ mixtures develops with steplike pulses in leader mechanism. The minimum breakdown voltages for the negative lightning and oscillating impulse voltages were higher than those for the positive.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.300-303
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• 1991

Sulphur-hexafluoride has extensively been used as an insulating gas of electric power equipment in substation for its high dielectric strength, non-toixity and non-flammable properties. But it is very expensive and is liquidizable under the condition of low temperature and high pressure. And it is very sensible to the locally high electric field strength. To resolve these problems, we studied 50% FOV and V-t characteristics of $SF_6-N_2$ mixtures under positive and negative lightning impulses using a 25mm rod-plane gap. 50% FOV of $SF_6-N_2$ 50% mixture was about 85% of pure $SF_6$ and it was known that $SF_6-N_2$ mixtures can be used as an economic substitution insulating gas for $SF_6$.

• Journal of Environmental Science International
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• v.22 no.1
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• pp.83-89
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• 2013

Silicon carbide with aluminium oxide was used to remove the sulphur hexafluoride ($SF_6$) gas using microwave irradiation. The destruction and removal efficiencies (DREs) of $SF_6$ were studies as a function of various decomposition temperatures and microwave powers. The decomposition of $SF_6$ gas was analyzed using GC-TCD. XRD (X-ray powder diffraction) and XRF (X-ray Fluorescence Spectrometer) were used to characterize the properties of aluminum oxide. DREs of $SF_6$ were increased as the microwave powers were increased. Additive aluminium oxide on SiC increased the removal efficiencies and decreased the decomposition temperature. The XRD results show that the ${\gamma}-Al_2O_3$ was transformed to ${\alpha}-Al_2O_3$ during $SF_6$ decomposition by microwave irradiation. It was found that the best material to control $SF_6$ was SiC with $Al_2O_3$ 30 wt% in consideration of microwave energy consumption and $SF_6$ decomposition rate.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.9
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• pp.533-540
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• 2000

Lightning impulse $(1.2/44[\mus])$ and damped oscillating impulse $(Osc./44[\mus])$ : 0.83[MHz]) breakdown characteristics in sulphur-hexafluoride/nitrogen (SF6-N2) mixtures were investigated. The predischarge currents were observed to clarify the breakdown mechanism. th experiments were carried out under nonuniform electric fields disturbed by a needle-shaped protrusion whose length and diameter are 10[mm] and 1[mm] at total gas pressure up to 0.5[MPa] with nitrogen concentrations varying from 5 to 20[%] in the mixture. The electrical breakdowns of SF6-N2 mixtures for both the positive and negative polarities develop with steplike pulses in leader mechanism and the breakdown voltage -time (V-t) characteristics were affected by the space charge. The voltage-time curves for the negative oscillating impulse voltage were extended over the longer time range. The minimum breakdown voltages for the negative lightning and oscillating impulse voltage were higher than those for the positive ones. in particular the positive breakdown voltages were independent of the gas pressure.

• Journal of Climate Change Research
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• v.8 no.3
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• pp.247-255
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• 2017

In this study, GHG inventory on 17 local government between 2005 and 2014 is build up using 'GHG emission estimation guideline (2016. 2) for local government' developed and distributed by KECO. This covers all the sectors should be included in national GHG inventory, which are energy, industrial process, agriculture, AFOLU, and waste. In addition, six GHGs, carbon dioxide, metane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, sulphur hexafluoride declared in Kyoto protocol are estimated to reflect utmost precision. Indirect esissions, such as electricity, heat and waste generation are separately estimated as well as direct emissions to help local government to establish substantial and implementable reduction measures of GHGs.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.8
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• pp.1305-1318
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• 2007

On a global scale agriculture and in particular enteric fermentation in ruminants is reported to produce about one fourth (21 to 25%) of the total anthropogenic emissions of methane ($CH_4$). Methane is produced during the anaerobic fermentation of hydrolyzed dietary carbohydrates in the rumen and represents an energy loss to the host besides contributing to emissions of greenhouse gases into the environment. However, there appears to be uncertainty in the $CH_4$ estimation from livestock due to the limited availability of data to document the variability at the farm level and also due to the significant impact of diet on the enteric $CH_4$ production. The methane mitigation strategies require robust prediction of emissions from rumen. There are many methods available which would be suitable for measuring $CH_4$ produced from the various stages of animal production. However, several factors need to be considered in order to select the most appropriate technique like the cost, level of accuracy required and the scale and design of the experiments to be undertaken. Selection of any technique depends on the accuracy as each one has its advantages and disadvantages. Screening of mitigation strategies may be evaluated using individual animal before large-scale trials on groups of animals are carried out. In this review various methods for the estimation of methane production from ruminants as well as for the determination of methane production potential of ruminant feeds are discussed. The advantages and disadvantages of the methods starting from respiration chamber, ventilated hood, facemask, sulphur hexafluoride ($SF_6$) tracer technique, prediction equations and meteorological methods to in vitro methods are detailed.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.10 no.6
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• pp.96-103
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• 1996

This paper describes the electron transport characteristics in SF6 gas calculated for range of E/N values from 150~ 800[Td) by the Monte Carlo simulation and Boltzmann equation method using a set of electron collision cross sections detennined by the authors and the values of electron swarm parameters are obtained by TOF method. The results gRined that the values of the electron swarm parameters such as the electron drift velocity, the electron ionization or Rttachment coefficients, longitudinal and transverse diffusion coefficients agree with the experimental and theoretical for a range of E/N. The properties of electron avalanches is concerned electron energy non--equilibrium region. The electron energy distributions function were analysed in sulphur hexafluoride at E/N : 500~800[Td) for a case of non-equilibrium region in the mean electron energy. The validity of the results obtained has been confilll1ed by a TOF method.