• Clean Technology
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• v.15 no.4
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• pp.273-279
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• 2009

$SF_6$, which has a high global warming potential, can be decomposed to sulfur and fluorine compounds through hydrolysis by $H_2O$ or oxidation by $O_2$ over solid acid catalysts. In this study ${\gamma}-Al_2O_3$ was employed as the solid acid catalyst for the abatement of $SF_6$ and its catalytic activity was investigated with respect to the reaction temperature and the space velocity. The catalytic activity for $SF_6$ decomposition by the hydrolysis reached the maximum at and above 973 K with the space velocity of $20,000\;ml/g_{-cat}{\cdot}h$, exhibiting a conversion very close to 100%. When the space velocity was lower than $45,000\;ml/g_{-cat}{\cdot}h$, the conversion was maintained at the maximum value. On the other hand, the conversion of $SF_6$ by the oxidation was about 20% under the same conditions. The SEM and XRD analyses revealed that the ${\gamma}-Al_2O_3$ was transformed to ${\alpha}-Al_2O_3$ during the hydrolysis and to $AlF_3$ during the oxidation, respectively. The size of $AlF_3$ after the oxidation was over $20\;{\mu}m$, and its catalytic activity was low due to the low surface area. Therefore, it was concluded that the hydrolysis over ${\gamma}-Al_2O_3$ was much more favorable than the oxidation for the catalytic decomposition of $SF_6$.

• Fibers and Polymers
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• v.6 no.3
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• pp.181-185
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• 2005

Silk fibroin (SF) nanofibers were prepared by electrospinning and their application as an enzyme immobilization support was attempted. By varying the concentration of SF dope solution the diameter of SF nanofiber was controlled. The SF nanofiber web had high capacity of enzyme loading, which reached to $5.6\;wt\%$. The activity of immobilized a-chymotrypsin (CT) on SF nanofiber was 8 times higher than that on silk fiber and it increased as the fiber diameter decreased. Sample SF8 (ca. 205 nm fiber diameter) has excellent stability at $25^{\circ}C$ by retaining more than $90\%$ of initial activity after 24 hours, while sample SF11 (ca. 320 nm fiber diameter) shows higher stability in ethanol, retaining more than $45\%$ of initial activity. The formation of multipoint attachment between enzyme and support might increase the stability of enzyme. From these results, it is expected that the electrospun SF nanofibers can be used as an excellent support for enzyme immobilization.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1334-1335
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• 2008

Although many studies have been carried out about binary gas mixtures with $SF_6$, few studies were presented about breakdown characteristics of $SF_6/CF_4$ mixtures. At present study the breakdown characteristics of $SF_6/CF_4$ mixtures in uniform and nonuniform field was performed. The experiments were carried out under AC voltages. The sphere-sphere electrode whose gap distance was 1 mm was used and the point-plane electrode whose gap distance was 3 mm was used in a test chamber. $SF_6/CF_4$ mixture contained 20% $SF_6$ and 80% $CF_4$ and the experimental gas pressure ranged from 0.1 to 0.5 MPa. The results show that addition of $SF_6/CF_4$ mixtures increase AC breakdown voltages. In uniform field the breakdown voltages of gas were linearly increased according to the pressure. However in nonuniform field the breakdown voltages of gas were increased nonlinearly.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2085-2087
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• 2005

In this paper the experiments of insulation characteristics by temperature change of $SF_6$ gas and liquid $SF_6$ in model GIS(Gas Insulated Switchgear) were described. From this results, the breakdown voltage was increased with a drop of temperature and an increase of the inner pressure in model GIS. The ability of insulation in liquid $SF_6$ was higher than that of the highly pressurized $SF_6$ gas. A liquid $SF_6$ discharge characteristics was caused by bubble formed evaporation of liquid $SF_6$ and bubble caused by high electric emission. It is considered that these result are fundamental data for electric insulation design of superconductor and cryogenic application machinery which will be studied and developed in the future.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.4
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• pp.115-121
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• 2007

This paper describes experiments of the breakdown characteristics by temperature change of $SF_6$ gas and Imitation Air(I-Air) in model GIS(Gas Insulated Switchgear). From the results of the experiments, the breakdown characteristics classify the vapor stage of $SF_6$ according to Paschen's law, in which the stage of coexistence for gas & liquid of the voltage value increases. This results in large deviation and the breakdown of the voltage(VB) low stage as the interior of the chamber is filled with a mixture of $SF_6$ that is not liquefacted and remaining air that can not be ventilated. The ability of $SF_6$ liquid($LSF_6$) insulation is higher than high-pressurize $SF_6$ gas. The VB of the I-Air decreases as the temperature drops and the VB also drops. It is considered that the results of this paper are fundamental data for the electric insulation design of superconductor and cryogenic equipment that will be studied and developed in the future.

• Korean Journal of Pharmacognosy
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• v.44 no.3
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• pp.291-297
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• 2013

Sophorae Flos (SF), a composite of flowers and flower-buds of Sophora japonica, has long been used in traditional Korean and Chinese medicines for the treatment of hemostasis and inflammation. In this study, we investigated anti-inflammatory effect of four EtOH extracts at the difference in blooming stages of flowers on LPS-induced inflammation in RAW264.7 cells. We classified the flowers of Sophora japonica with SF-1 (length of flower is shorter than calyx), SF-2 (length of calyx is shorter than flower), SF-3 (full bloom), and SF-4 (not blooming at all). We examined HPLC analysis, whether quercetin and rutin are major component of these Sophorae Flos extracts or not. As a result, SF-1 contained quercetin, but the others did not. In addition, quercetin, SF-1, and SF-4 act on the suppression of pro-inflammatory mediators including inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, nitric oxide (NO), prostaglandin E2 ($PGE_2$) against lipopolysaccharide (LPS)-induced activation in RAW264.7 cells. Of these, SF-1 showed the best anti-inflammatory effect. These results suggest that Sophorae Flos with the highest content of quercetin would be used for the treatment of various inflammation diseases.

• International Journal of Industrial Entomology and Biomaterials
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• v.2 no.1
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• pp.15-18
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• 2001

Silk fibroin (SF) derided from the domestic silk worm, bombyx mori, is the natural protein and widely used as bio-functional materials as well as apparels. We studied the livers protective effect of SF from alcohol-induced hepatotoxicity in the alcohol preference mouse. To increase more absorption of SF in experimental animals, molecular weight of SF was lowered by 2N of HCI aqueous solution at 10$0^{\circ}C$ for 48 hrs. SF was added to liquid diet with alcohol and fed to the alcohol preference mice for 4 weeks. To assess the liver function, the concentration of alanine aminotransferase (AlT), aspartate aminotransferase (AST) and cholesterol present in either blood or liver tissue were measured. As compared with non-SF treated groups the SF-treated showed significantly low concentrations of ALT, AST, cholesterol and triacylglycerol values, respectively. Histopathological examination revealed that the extent of hepatocyte injury in the SF-treated group was reduced when it was compared with non SF-treated group. These results suggest that SF may have liver protective effects against alcohol-induced hepatotoxicity.

• Journal of Trauma and Injury
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• v.20 no.2
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• pp.83-89
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• 2007

Purpose: This research was performed to determine which clinical signs and symptoms of brain injury are sensitive indicators of skull fracture (SF) and intracranial injury (ICI) in head injured children. Methods: We conducted a prospective study of minor head trauma in children younger than 2 years of age for a 1-year period. Skull radiographs, brain computed tomography (CT), and data forms, including mechanism of injury, symptoms, physical findings, and hospital course, were completed for each child. Results: Of 137 study subjects, 17 (12.4%) had SF/ICI. Falls were the most common mechanism of injury, and heights of fall above 1 meter were associated with incidence of SF/ICI (p<0.05). Scalp abnormalities were not associated with incidence of SF/ICI. As for clinical symptoms, lethargy and a grouping of features (irritability & vomiting) were associated with incidence of SF/ICI (p<0.05). The incidence of seizure, loss of consciousness, vomiting, irritability, and scalp abnormality did not differ significantly between those with normal radiologic findings and those with SF/ICI. Among asymptomatic patients, 11 (14.5%) patients had SF/ICI, and among patients with normal scalp findings, 9 (12.7%) patients had SF/ICI. Conclusion: Clinical signs and symptoms, except for lethargy and a grouping of features (irritability & vomiting), were not sensitive predictors of SF/ICI. Nevertheless, SF/ICI occurred among normal children. In such a case, a liberal policy of CT scanning is warranted.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.213-215
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• 2008

최근 지구온난화가 국제적인 이슈화되면서 온실가스의 효과적인 처리에 많은 관심이 집중되고 있다. 냉매로 주로 사용되는 HFC-134a와 절연제로 주로 사용되고 있는 $SF_6$는 각각 이산화탄소의 11,700배와 23,900배의 지구온난화지수를 가지는 온실가스이다. 본 연구에서는 이 두 물질의 효과적인 분리/회수를 위하여 가스 하이드레이트 형성을 이용한 방법을 제안하였다. 하이드레이트 형성법을 이용 할 경우 공정이 단순하고 저압에서 분리가 가능하므로 타 분리공정과의 경쟁이 가능할 것으로 예상된다. 본 실험은 275-290 K의 온도범위와 3 - 30 bar의 압력범위에서 질소 + HFC-134a (20, 40, 60, 80%)와 질소 + $SF_6$ (10, 30, 50, 70%)의 혼합기체를 사용하여 각 조성에 따른 하이드레이트(H)-물($L_W$)-기상 (V)의 3상 평형점을 측정하였다. HFC-134a 또는 $SF_6$의 조성이 낮은 혼합기체의 3상 평형점은 순수 질소의 3상 평형점에 비하여 주어진 온도에서 평형압력이 현저히 낮은 것을 볼 수 있었으며 HFC-134a 또는 $SF_6$의 조성이 증가할 수록 순수한 HFC-134a 또는 $SF_6$의 3상 평형점에 근접하는 것을 볼 수 있었다. 특히 $SF_6$는 다른 기체와 달리 하이드레이트의 생성/해리에 긴 시간이 필요하다는 것을 알 수 있었다. 본 실험에서 얻어진 결과는 하이드레이트를 이용한 HFC-134a와 $SF_6$ 분리 공정의 중요한 기초 자료가 되며 다른 혼합 기체의 분리 공정에도 응용될 수 있을 것이다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.3
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• pp.43-47
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• 1985

This paper describes fiber-optic current sensor using SF-4 flint glass for the first time, ails the flint glass has been theoretically analyzed by jones matrix and experimentally verified. Verdet constant of SF-4 flint glass, which determines the sensitivity of current sensor, has been experimentally found as 0.0606(min/g.cm). It is relatively lower value than currently used faraday rotators such as FR-5, SF-6 flint glasses and YIG. The fiber.optic current sensor system was established and the current measurement was performed in the range of 100-600 (A) and 100- 500 (G). It has beenfhown by the experi-mental results that the detector output linearly increased in proportion to the current. Since these experimental results were in good agreement with theoretical results, it has been shown that SF-4 flint glass can be used for the magnetooptic current sensor.