• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.57-60
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• 2005

This paper describes the experimental results of the pre-breakdown phenomena in $SF_6/CO_2$ mixtures under non-uniform electric fields caused by positive and negative lightning negative voltages. $SF_6/CO_2$ mixtures have an advantage of an environmental aspect and cost reduction, and safety aspects. In order to analyze the pre-breakdown processes in $SF_6/CO_2$ mixtures stressed by impulse voltages, pre-breakdown current and luminous signals were measured by a shunt and a photo-multiplier tube, respectively. Dielectric strengthes of $SF_6/CO_2$ mixtures were investigated. Additionally, characteristics of discharge channels were observed by high speed cameras and the physical properties were discussed. The pre-breakdown propagates with a stepwise process. The in to breakdown from the corona onset point in positive polarity was shorter than that in negative polarity. The time intervals of positive leaders are shorter than those of negative leaders, and the path of positive leader channel is zigzag.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.237-240
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• 2004

Sulfur Hexafluoride, SF6 is widely used for leak detection and as a gaseous dielectric in transformers, condensers and circuit breakers. SF6 gas is also effective as a cleanser in the semiconductor industry. This paper presents a numerical study of the sealing force of disk type seal in SF6 gas safety valve. The sealing force on the disk seal is analyzed by the FEM method based on the Taguch's experimental design technique. Disk seals in SF6 gas safety valve are designed with 9 design models based on 3 different contact length, compressive ratio and gas pressure. The calculated results of Cauchy stress and strain showed that the sealing characteristics of Teflon PTFE is more effective compared to that of FKM(Viton), which is related to the stiffness of the materials. And also, the contact length of the disk seal is important design parameter for sealing the SF6 gas leakage in the safety valve.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.298-301
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• 2006

This paper describes the electron energy distribution function characteristics in $SF_6-Ar$ gas calculated for range of E/N values from $50\sim700[Td]$ by the Monte Carlo simulation(MCS) and Boltzmann equation(BE) method using a set of electron collision cross sections determined by the authors and the values of electron swarm parameters are obtained by time of flight(TOF) method. In this dissertation the results of the combined experimental and theoretical studies designed to understand and predict the spatial growth and transport coefficients for electrons in $SF_6$ and $SF_6-Ar$ mixtures have described. The ionization and attachment coefficients in pure $SF_6$ and $SF_6-Ar$ mixtures have been calculated over the range of 10$SF_6$ molecule and for Ar atom proposed by other authors. The results obtained in this work will provide valuable information on the fundamental behaviors of electrons in weakly ionized gases and the role of electron attachment in the choice of better gases and unitary gas dielectrics or electro negative components in dielectric gas mixtures.

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.5
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• pp.611-618
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• 1999

An efficient and effective access to needed information becomes an important factor in the modern information society. Many people have developed information retrieval (IR) systems that retrieve needed information from a large amount of data at a given time. However, most freely available IR systems have been developed for English text rather than for Korean text. In this research, we have analyzed the IR system freeWAIS-sf, and localized it with the Korean morphological analyzer, namely HAM. The localized freeWAIS-sf can handle both English text and Korean text simultaneously. We have also modified the weighting scheme of freeWAIS-sf. The experimental result shows that the modified weighting scheme outperforms the original one in terms of retrieval effectiveness.

• Molecules and Cells
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• v.45 no.10
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• pp.718-728
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• 2022

Splicing factor B subunit 4 (SF3B4), a component of the U2-pre-mRNA spliceosomal complex, contributes to tumorigenesis in several types of tumors. However, the oncogenic potential of SF3B4 in lung cancer has not yet been determined. The in vivo expression profiles of SF3B4 in non-small cell lung cancer (NSCLC) from publicly available data revealed a significant increase in SF3B4 expression in tumor tissues compared to that in normal tissues. The impact of SF3B4 deletion on the growth of NSCLC cells was determined using a siRNA strategy in A549 lung adenocarcinoma cells. SF3B4 silencing resulted in marked retardation of the A549 cell proliferation, accompanied by the accumulation of cells at the G0/G1 phase and increased expression of p27, p21, and p53. Double knockdown of SF3B4 and p53 resulted in the restoration of p21 expression and partial recovery of cell proliferation, indicating that the p53/p21 axis is involved, at least in part, in the SF3B4-mediated regulation of A549 cell proliferation. We also provided ubiquitination factor E4B (UBE4B) is essential for p53 accumulation after SF3B4 depletion based on followings. First, co-immunoprecipitation showed that SF3B4 interacts with UBE4B. Furthermore, UBE4B levels were decreased by SF3B4 depletion. UBE4B depletion, in turn, reproduced the outcome of SF3B4 depletion, including reduction of polyubiquitinated p53 levels, subsequent induction of p53/p21 and p27, and proliferation retardation. Collectively, our findings indicate the important role of SF3B4 in the regulation of A549 cell proliferation through the UBE4B/p53/p21 axis and p27, implicating the therapeutic strategies for NSCLC targeting SF3B4 and UBE4B.

• Journal of Digital Convergence
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• v.13 no.7
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• pp.349-357
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• 2015

Giant character used various SF movies and games in media convergence ages, and is essential for giant character in success contents. It This study defined giant character of SF movies and games, it analysed the eight of external characteristics and internal characteristics of giant character in SF movies and games. The external characteristics defined shape, silhouette, size and color, the internal characteristics defined fear, satanism, image and story focus, playfulness. Above, it was structured positioning model of giant character based eight characteristics and analyzation of example of SF movies and games. The elements of positioning model of giant characters are darkness, huge, abnormal, human, animal, fear, satanism, story focused, image focused and playfulness, and this study was proposed these model of elements of eight in SF movies and games.

• Journal of Sensor Science and Technology
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• v.8 no.3
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• pp.291-297
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• 1999

The plasma etching of tungsten thin films has been studied with $SF_6$ gas in RIE system. The etch rate of ${\alpha}$-phase W film with $SF_6$ gas plasma has been showed to depend strongly on process parameters ($SF_6$, $SF_6-N_2$ gas). Effect of $N_2$ addition and etching selectivity between W film and photoresist have also been studied in detail. Etching profiles between W film and photoresist were investigated by SEM. The compounds on W surface after $SF_6-N_2$ gas plasma treatment were examined by XPS and the concentration of F ions was detected by OES during plasma on.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.6
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• pp.75-80
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• 2006

The disastrous accident happens and the economic loss comes into being at the power facilities that used a industry site, if the fault comes into being. This paper experiments the partial discharge in the GIS used a $SF_6$ insulation gas by the pressure change. We studied the influence of particles at the partial discharge in a $SF_6$ gas. We use UHF method and measure the partial discharge signal radiation electromagnetic waves and to be happened at the $SF_6$. And we analyzed the influence on the $SF_6$ gas to have the particles which the partial discharge analyzes a spectrum of the radiated electromagnetic waves and comes out. The paper results aided the prevention of breakdown accident that happened by particles when an inside pressure changes at the GIS & the power facilities used $SF_6$ gas.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4745-4757
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• 2015

This research has been conducted to understand relations in general hospital nurses health level (SF-36), sociodemographic characteristics, health related factors, job related factors, and job stress. The subjects of the research are 572 nurses who are working in six different general hospitals with 250 beds. Data which has been collected from self administered questionnaire during the period from May 1st, 2014 to may 31th. The result has described, the health level(SF-36) of nurses has strong relation to sociodemographic characteristics, health related factors, job related factors, and even job stress. Especially the health level (SF-36) of nurses has risen when the nurses have less job stress, lower job pressure and more support from supervisor and coworkers. Therefore, the primary things to create are system development and atmosphere which controls the nurses' job stresses. Moreover, it is also important to develop programs for nurses' career satisfaction.

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.4
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• pp.326-332
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• 2017

$SF_6$ (sulfur hexafluoride) gas has an extremely high global warming potential (GWP). Therefore, there has been an effort to reduce of $SF_6$ its emission into atmosphere. In this study, $SF_6$ was injected into the plasma reactor directly, decomposed particulate matter of $SF_6$ was analyzed. Destruction and removal efficiency (DRE) of $SF_6$ were tested with varying degrees of plasma power and initial concentrations of $SF_6$ (1,000 ppm). This study is conducted with plasma power which are 4.4 kW, 5.5 kW, 6.0 kW, 6.6 kW, 7.6 kW, 8.1 kW and 9.1 kW. It was confirmed through experiment that the decomposition efficiency of $SF_6$ is 100% at 7.6 kW of the plasma power. In addition, the particulate matter is formed as minute particles of which size is $1{\mu}m$ and the main component of particulate matter is identified as $AlF_3$.