• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.291-295
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• 2002

O-ring seal is usual component part in various mechanical apparatus for sealing that makes efficient performance of the equipments. The sealing performance of O-ring is affected in environments of the O-rings, like that applied pressure, working temperature, pre-compressed ratio and materials. In this paper, a pressurized, compressed elastomeric bi-polymer O-ring inserted into a rectangular groove is analyzed numerically using the MARC finite element program. The calculated FEM results showed that bi-polymer O-ring that is manufactured by NBR for an inner and FFKM for an outer ring shows a low temperature distribution among various bi-polymer O-ring models. But, the normal contact stress between the flange and upper part of the O-ring is small compared to other bi-polymer model.

• Journal of Chest Surgery
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• v.26 no.12
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• pp.950-954
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• 1993

Two patients with chronic Budd-Chiari syndrome resulting from segmental obstruction of the inferior vena cava underwent operation. There were 1 man and 1 woman. The obstructed segment was directly visualized by a transthoracic, transdiaphragmatic, retroperitoneal approach. In these two cases, severe segmental obstruction of the inferior vena cava was observed just above the right hepatic vein. These patients underwent successful retrohepatic cavoatrial bypass with a polytetrafloroethylene [PTFE] graft [ 16mm plain and 16mm ringed graft ]. There were no operative mortality and postoperative complication. These patients have been followed up for 6months and 36months without evidence of re-obstruction. When there is a severe stricture of the IVC with hepatic veins draining freely into the obstructed segment of the IVC, a dorsal cavoatrial bypass with a PTFE graft, preferably ringed, is the method of choice.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.03a
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• pp.113-134
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• 1995

GORE-TEX MEMBRANE은 PTFF(POLYTETRA FLUOROETHYLENE)를 특수가공하여 극히 미세한 구조를 가지는 연속다공질체로 만들어 습,건식용 산업용 여과재로써 활용하므로써 그동안 사용되어오던 종래의 심층여과방식의 여과포로서는 도저히 이룰 수 없었던 표면여과기능을 갖춤에 따라 높은 집진효율이나 낮은압력손실로 동시에 운전을 가능하게한 새로운 기능의 첨단여과포로써 각종산업분야에 이미 널리 적용되고 있다. 근래 BOILER, 소각로, 제철, 제강용로등의 고온용 BAG FILTER 소요가 증가됨에 따라 보다 효율적이고 경제적인 고온용 여과포에 대한 관심이 높아지고 있으며, 특히, 소각로, 발전설비, CEMENT 생산공정중 KILN 공정등에 주로 사용되어오던 전기 집진기 (ELECTROSTATIC PRECIPITATOR)의 집진효율이 DIOXINE 이나 FURAN 등의 새로운 규제와 중금속, 혹은 분진들에 대해 강화되는 환경 규제치에 적응하기 어려워짐에 따라 BAG FILTER로의 전환/개선 방안이 많이 연구되고 있으며 이미 활용되어지는 부분도 있는바 이에 대한 새로운 적용방법등을 소개하고자 한다.

• Journal of Chest Surgery
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• v.33 no.9
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• pp.716-722
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• 2000

Background: Modified Blalock-Taussig shunt using 3mm or 3.5mm PTFE graft has been performed in patients with small body weight or in candidates for single ventricle palliation. However, there are few reports concerning clinical outcomes in terms of pulmonary artery growth and shunt patency rate after shunt operations using such a small graft. Material and Method: Twenty-five patients rate after shunt operations using 3 or 3.5 mm sized grafts from September 1996 to August 1999. We retrospectively assessed the pulmonary artery growth and the shunt patency rate by reviewing the pre-and post-operative pulmonary angiograms. The risk factors for late death and second shunt operations were also analyzed. To assess the presence of any correlation between body weight and selection of the graft size, regression analysis was done in 81 cases of shunt operations performed during the same period. Result: There were 1(4%) early death and 5(20%) late deaths. The survivors were followed up for an average of 7.34 months. The pulmonary artery index increased significantly from 129$\pm$66$\textrm{mm}^2$/$m^2$ to 213$\pm$114 $\textrm{mm}^2$/$m^2$(p=0.002). The shunt patency rate assessed at postoperative 2, 4, 6 and 8 months were 82.5%, 77%, 73% and 42% respectively with a marked decline between 6 and 8 months. Asplenia was a frequent finding for the patients with late death although the incidence failed to reach statistical significance(p=0.078). Pre-operative diagnosis of PA with VSD was found to be a statistically significant risk factor for a second shunt operation(p=0.01). Body weight(a) at operation and graft size(b) used in the shunt operations revealed strong correlation and could be expressed by the following formula; b=0.128a + 3.233. Conclusion: Adequate growth of pulmonary artery and satisfactory early patency rate could be obtained by modified Blalock-Taussing shunt using 3mm or 3.5mm graft. However, during 6 to 8 months after shunt operations, the patency rate fell sharply, which implicates that close observation and early intervention are mandatory in this period.