• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.62.3-63
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• 2016

We studied the young stellar populations of star-forming (SF) regions in M33 based on the Galaxy Evolution Explorer (GALEX) ultraviolet (UV) imaging data. The SF regions are defined from far-UV data with various thresholds. We examined the reddening and spatial distribution of hot massive stars within SF regions from Hubble Space Telescope multi-band survey and Local Group Galaxy Survey (LGGS) data. The H-alpha sources from the LGGS are used for comparing with the spatial distribution of SF regions. The GALEX UV flux measurements of SF regions are used to derive their ages and masses. We also estimated the size and density of SF regions. The younger and compact SF regions are often arranged within older and sparser SF complexes. The results allow us to understand the hierarchical star formation and recent evolution of M33.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.130-136
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• 2003

A FQI(fatigue quality index) analysis using the concept of SF(severity factor) is performed to various shape of elliptical hole. FQI is fatigue quality index to estimate the dynamic SF from static SF by finite element analysis. Since the SF is affected by the location of cutout in plate and radius ratio, static SF is analyzed with finite element method and forms the equation of FQI for predicting a dynamic SF. To examine the validity, dynamic SF is measured by photoelastics and thermalelastics for an epoxy resin plate with various elliptical holes under dynamic load.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.516-520
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• 2009

Atmosphere Plasmas of Gas Discharge (APGD) have been used in plasma sources for material processing such as etching, deposition, surface modification, etc. This study is to investigate and understand the fundamental plasma discharge properties. Especially, $SF_6/N_2$ mixed gas would be used in power transformer, GIS (Gas insulated switchgear) and so on. In this paper, we developed a one dimensional fluid simulation model with capacitively coupled plasma chamber at the atmosphere pressure (760 [Torr]). 38 kinds of $SF_6/N_2$ plasma particles which are an electron, two positive ions (${SF_5}^+$, ${N_2}^+$), five negative ions (${SF_6}^-$, ${SF_5}^-$, ${SF_4}^-$, ${F_2}^-$, ${F_1}^-$), thirty excitation and vibrational particles for $N_2$ were considered in this computation. The $N_2$ gases of 20%, 50%, 80% were mixed in $SF_6$ gas. As the amount of $N_2$ gas was increased, the properties of electro-negative plasma moved toward the electro-positive plasma.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.281-284
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• 2004

Mean energy of electrons in $SF_6-Ar$ Mixtures Gas used by MCS-BEq algorithm has been analysed over the E/N range $30{\sim}300[Td]$ by a two term Boltzmann equation and by a Monte Carlo Simulation using a set of electron cross sections determined by other authors, experimentally the electron swarm parameters for 0.2[%] and 0.5[%] $SF_6-Ar$, 0.1[%] and 5.0[%], $SF_6-Ar$ mixtures were measured by time-of-flight(TOF) method. The transport Coefficients for electrons in (100[%])$SF_6$. (100[%])Ar, (0.2[%])$SF_6-Ar$ and (0.5[%]) $SF_6-Ar$, (5.0[%]) $SF_6-Ar$, (0.1[%])$SF_6-Ar$ mixtures were measured by time-of-flight method, and the electron energy distribution function and the parameters of the velocity and the diffusion were determined by the variation of the collision cross-sections with energy. The results obtained from Boltzmann equation method and Monte Carlo simulation have been compared with present and previously obtained data and respective set of electron collision cross sections of the molecules.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.3
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• pp.86-93
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• 2016

It is very desirable that a mixture gas possessing excellent insulation performance is suggested for insulation on increasing high voltage. This paper proposes a $SF_6$ mixture gas based on the factors including dielectric strength, environmental impact and economic feasibility of manufacture for the insulation in eco-friendly power equipment. A suitable-$SF_6$ content was determined to improve the dielectric strength in $N_2$ and Dry Air. The examination results of the factors revealed that a $SF_6$/Dry Air mixture gas possessing the $SF_6$ content was more appropriate than a $SF_6/N_2$ mixture gas to the eco-friendly power equipment. In addition to the selection of the suitable $SF_6$ mixture gas, insulation characteristics as a function of $SF_6$ content were described from electron-detachment mechanism.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.2
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• pp.114-119
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• 2000

Etch characteristics of SF6/CI2 electron cyclotron resonance (ECR) plasmas have been investigated. Surface reaction of gas plasma with polysilicon was also analysed using X-ray photoelectron spectroscopy (XPS). At the same time, the relationship between surface reaction and the etched profile of polysilicon was examined using XPS. The etch rate of polysilicon and oxide increases with increasing flow rate of SF6 in the SF6/CI2 gas mixture, and tis selectivity also increase also increase. It was also found that as increasing flow rate of SF6 in the SF6/CI2 gas mixture, the atomic% of chlorine detected at surface region decrease, but F and S contents increase. At the same time, when the mixing ratio of SF6 gas increases, the anisotropy of etched polysilicon is sharply decreased in the 0%~10% range of the SF6 mixing ratio, but is rarely varied in the range over 10%, in spite of the large variations in flow rates. It can be explained that the bonding of S-Si due to SiSx(x$\leq$2) compound formed on the etched surface suppress the formation of Si-Cl and 'or Si-F bonding in the silicon etching.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.482-483
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• 2007

본 논문에서는 GIS 설계에 있어 기초가 되는 준평등전계 하에서의 가스 절연특성을 검토하기 위하여 순 $SF_6,\;N_2,\;CO_2$ 이들이 혼합된 2종 및 3종 혼합가스에 대해 가스압력 0.6MPa 이하에서 상용교류전압을 인가하여 실험에 의해 그 부분방전특성과 절연특성을 조사하였다. 특히 실용 전력기기의 경우 금속이물질 등의 혼입에 의해 기기 내에서 불평등전계가 형성되어 부분방전을 거쳐 절연파괴에 이르는 가능성이 있으므로 본 연구에서는 불평등전계 하의 절연특성을 검토하였다. 실험 결과 $SF_6/N_2$ 2종 혼합 가스에 비하여 $SF_6/N_2/CO_2$ 3종 혼합 가스의 교류 절연 특성이 향상됨을 확인하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.4
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• pp.635-640
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• 2008

New gas mixtures are now finding applications such as interrupting media for high-voltage circuit breakers. These mixtures consist of a high content of carbon tetrafluoride($CF_4$) added to sulfur hexafluoride($SF_6$). Nowdays $SF_6$ has been established for the use in gas insulated substations due to its high insulation withstand level and good arc quenching capability. At this paper Breakdown characteristics were investigated for $SF_6/CF_4$ mixtures when AC voltage and standard lightning impulse voltage(LI) was applied in a needle-plane electrodes. And partial discharge(PD) experiments were carried out in the test chamber which was made in needle-plane electrode. And ${\Phi}$-Q-N distribution of partial discharge signals was analyzed. The total pressure of the $SF_6/CF_4$ mixtures was varied within the range of 0.1-0.5 Mpa in the test chamber. The breakdown voltage in needle-plane electrode displayed N shape characteristics for increasing the content of $SF_6$ at positive impulse voltage and the PD inception voltage was increased slightly when pressure of $SF_6/CF_4$ Mixtures was increased. Maximum PD inception voltage is showed in 80% SF6/20%$CF_4$.

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.2
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• pp.142-146
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• 2003

Three insect cell lines, Sf9, Sf21 and Tn5Bl-4, and four different kinds of serum free media (SFM), Sf 900 II, EX-CELL 420, EX-CELL 405 and Express Five, were used to compare the nutrient consumption, byproduct formation, production of recombinant protein and protease activity in suspension cultures. The Sf 900 II SFM was a ppropriate for the cell growth and protein production of the Sf9 and Sf21 cell lines. When the Tn5Bl-4 cell line was grown in the Express Five SFM, the specific growth rate was 1.6 fold higher than those of either the Sf9 or Sf21 cell lines. The glucose and glutamine consumption rates per cells, were 4 and 2.3 times higher than those of the Sf9 cell line, respectively. The overall yield coefficients of the lactate and ammoniumion were 2.8 and 1.5 times higher compared to those of the Sf9 cell line. respectively. The maximum specific ${\beta}$-galactosidase production rate was 4.5 fold that of the Sf9 cell line, a 3 times higher protease activity per cell.

• Molecules and Cells
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• v.24 no.3
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• pp.372-377
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• 2007

The orphan nuclear receptor, SF-1, plays a pivotal role in the development and differentiation of the endocrine and reproductive systems, and also regulates the transcription of a host of genes, including those encoding several steroidogenic enzymes and gonadotropins. We found that a previously unidentified repressor, EID-1, is an SF-1-interacting protein that inhibits the transactivation of SF-1. A transient transfection assay revealed that EID-1 inhibits SF-1, but not LRH-1, $ERR{\gamma}$, or mCAR. Using the yeast two hybrid and GST pull-down assays, we determined that EID-1 interacted strongly with SF-1. In addition, it colocalized with SF-1 in mammalian cells and interacted specifically with the AF-2 domain of SF-1, competing with SRC-1 to inhibit SF-1 transactivation. EID-1 is expressed in the mouse testis, and its expression decreases during testis development. The results of the present study suggest that EID-1 can act as a repressor, regulating the function of SF-1.