• 한국진공학회:학술대회논문집
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• 한국진공학회 2002년도 제23회 학술발표회 초록집
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• pp.176-176
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• 2002

• 한국전기전자재료학회논문지
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• 제26권6호
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• pp.429-433
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• 2013

PTFE composites for use of microwave substrate were fabricated by impregnation and heat treatment fabrication with glass fabric. This study shows dielectric properties such as dielectric constant and loss can be controlled by thickness of PTFE composite with change of pressure condition in heating press process. The dielectric constant of the PTFE composites has decreasing tendency as given higher pressure condition. The dielectric loss has similar result too. Especially, the case of the dielectric loss was affected by the condition of pressure at heating press and had the best performance under 3 MPa. In order to see the reason why thickness conditions make different, their microstructures were also observed.

• 대한방사선기술학회지:방사선기술과학
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• 제23권1호
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• pp.97-101
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• 2000

In this study, the highly sensitive $CaSO_4:Tm$-PTFE TLDs has been fabricated for the purpose of measurement of high energy electron. $CaSO_4:Tm$ phosphor powder was mixed with polytetrafluoroethylene(PTFE) powder and moulded in a disk type(diameter 8.5 mm. thickness $90\;mg/cm^2$) by cold pressing. The absorbed dose distribution and ranges for high energy electron were measured by using the $CaSO_4:Tm$-PTFE TLDs. The ranges determined were $R_{100}=14.5mm$, $R_{50}=24.1mm$ and $R_P=31.8mm$, respectively and the beam flatness, the variation of relative dose in 80% of the field size, was 4.5%. The fabricated $CaSO_4:Tm$-PTFE TLDs nay be utilized in radiation dosimetry for personal, absorbed dose and environmental monitoring.

• Journal of Chest Surgery
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• 제18권2호
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• pp.314-319
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• 1985

Nineteen patients with various types of cyanotic congenital heart disease underwent systemic-pulmonary artery shunts with a microporous polytetrafluoroethylene [PTFE] graft between September, 1983, and April, 1985. Age ranged from 3 months to 18 years, and seven of them were less than 12 months old. There were seventeen Great Ormond Street type of modified Blalock-Taussig shunts, and two central polytetrafluoroethylene shunt [ascending aorta-right pulmonary artery]. There was one postoperative death [1/19=5.3%] in a 10 Kg child born with pulmonary atresia and ventricular septal defect associated with patent ductus arteriosus. He had another anomaly of imperforated anus. Relief from cyanosis was achieved in other eighteen patients with variable degree. Eighteen survivors have been followed up from 1 month to 19 months. Clinical status, auscultation, oxygen partial pressure of arterial blood, and hemoglobin have been used to establish shunt patency in all survivors. By above criteria, all survivors have good patent shunt.

• Tribology and Lubricants
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• 제20권1호
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• pp.1-6
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• 2004

In order to identify the effect of lubricant films on abrasive abilities of diamond films, wear rates of Ruby balls slid over as grown diamond films and polytetrafluoroethylene films coated diamond films were compared by using pin-on-disk tribometer. Wear scars of Ruby balls were measured by SEM. Results showed that wear rates of Ruby balls slid over polytetrafluoroethylene coated diamond films were about 4 times lager than as grown diamond films. Coefficients of friction decreased with sliding distance at diamond disks but were almost unchanged at polytetrafluoroethylene coated ones. These results came from behaviors of wear debris, which adhered more strongly in the tracks of as grown diamond films than polytetrafluoroethylene coated ones.

• 센서학회지
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• 제29권2호
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• pp.89-92
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• 2020

Polytetrafluoroethylene (PTFE) fibers are widely used in the textile industry, filter media, membrane distillation, electronic appliances, and construction. In this study, PTFE-polyethylene oxide (PEO) fibrous membranes were fabricated by emulsion electrospinning; subsequently, pure PTFE nanofibers were obtained via sintering. PTFE-PEO electrospinning solutions were prepared using different weight ratios to determine the optimized condition. As the ratio of the PEO increased, the fiber structure improved. Scanning electron microscopy and Fourier-transform infrared spectroscopy observations indicate that PEO is removed and PTFE fused gradually to form bonds among them during sintering. The obtained pristine PTFE membrane demonstrated hydrophobicity at 143.6° water contact angle and oleophilicity at 0° oil contact angle, which is known to be utilized for oil/water separation. A simple separation experiment was performed to remove oil droplets from water. The PTFE membrane exhibited good chemical stability and a high surface-area-to-volume nanofiber ratio. These excellent properties suggest that it is applicable to oil/water separation in harsh chemical environments.

• 한국수소및신에너지학회논문집
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• 제20권4호
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• pp.291-299
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• 2009

Ni-plated polytetrafluoroethylene(Ni-PTFE) particles($25{\mu}m$, $500{\mu}m$) were prepared by using nickel electroless plating. The Ni content in Ni-PTFE particles increased with increasing the amount of reduction agent. At about 53 wt% Ni content, $25{\mu}m$ Ni-PTFE particles showed conductivity of 320S/m. The Ni-PTFE particles were formed into the Ni-PTFE plate using heat treatment at $350^{\circ}C$ under $10{\sim}1000kg/cm^2$. The Ni-PTFE plate displayed the high conductivity of 5100S/m due to the formation of 3-dimentional Ni network. The plate was used as an electrode in an alkaline fuel cell(AFC). In terms of the current density, the Ni-PTFE electrode having higher Ni content(53 wt%) showed improved performance.

• 한국전기전자재료학회논문지
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• 제19권12호
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• pp.1167-1171
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• 2006

This work describes the effect of binders, such as carboxymethylcellulose (CMC), CMC+ Polytetrafluoroethylene (PTFE) and PTFE, on the electrochemical and mechanical properties of activated carbon-electrode for electric double layer capacitor. The cell capacitors using the electrode bound with binary binder composed of CMC and PTFE, especially in composition CMC PTFE = 60 : 40 wt.%, has better rate capability and the lower internal resistance than those of the cell capacitor with CMC. On the other hand, the sheet type electrode kneaded with PTFE was bonded with conductive adhesive on Al foil. This cell capacitor using the electrode with PTFE exhibited the best mechanical properties and rate capability compared to the CMC and CMC+PTFE one. These behaviors could be explained by the well-developed network structure of PTFE fibrils doting the kneading process.

• Bulletin of the Korean Chemical Society
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• 제31권2호
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• pp.281-285
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• 2010

Hemodialysis vascular access dysfunction (HVAD) due to the aggressive development of venous neointimal hyperplasia remains a major complication for patients with synthetic arteriovenous grafts. Paclitaxel-coated expanded polytetrafluoroethylene (ePTFE) grafts effectively prevent neointimal hyperplasia and stenosis. However, perigraft inflammation or edema can be another complication of ePTFE grafts, preventing early cannulation. Three different types of ePTFE grafts, including grafts without paclitaxel coating (control group, n = 12), grafts with paclitaxel coating at a dose density of $0.61ug/mm^2$ (low concentration group, n = 12), and grafts with paclitaxel coating at a dose density of $1.15ug/mm^2$ (high concentration group, n = 12) were placed in the backs of 12 rabbits, simultaneously. Six rabbits were euthanized after one week and the remaining six were euthanized two weeks after implantation. Perigraft inflammation, graft wall inflammation, stromal cell proliferation, blood vessel formation, tissue necrosis and edema were analyzed for the grafts in each animal. Inflammation surrounding the paclitaxel-coated grafts was significantly reduced compared to the control group. Stromal cell layers were detected at the interface between the graft and the surrounding tissue in the control group, infiltrated into the graft interstices, and differentiated into myofibroblasts for graft healing. Paclitaxel-coated grafts inhibited stromal cell proliferation and infiltration into the graft wall. Tissue necrosis and edema were not detected in either of the paclitaxel-coated graft groups.

• Journal of Chest Surgery
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• 제29권8호
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• pp.836-843
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• 1996

본 연세대학교 의과대학 흉부외과학 교실에서는 1985년 부터 1992년까지 청색성 선천성 심장기형환자에서 시행한 체 폐동맥 단락술에 사용되 었던 PTFE (polytetrafluoroethylene) 인조 혈관을 재수술시 절 제하여 꽝학 현미경 및 전자 현미경으로 관찰하였다. 체폐 동맥 단락술의 종류는 Blalock-Taussig형 10 례. Waterstone-Cooley형 1례, Pott 형 1례등이었다. 사용된 PTFE 인조 혈관의 크기는 5mm가 10개, 4mm가 1개, 6mm가 1개였다 이들의 평균 사용 시간은 31개월(12개월에서 55개월)이었다. 10개월에서 20개월사이의 PTFE 인조 혈관은 틈새에 매우 많은 혈소판이 끼어 있었고 내막 비후가 관찰되었다. 40 개월이상 기능을 하는 PTFE 인조 혈관에서는 혈관 내피 세포가 광학 및 전자 현미경으로 관찰되었다. 막힌 PTFE 인조 혈관의 내면은 매우 심한 내막 비후와 혈전으로 차 있었다. 이와 같은 우리의 경험을 토대로 PTFE인조 혈관과 자신의 혈관이 연결되는 부위에 결체조직이 잘붙어 혈관내피세포가 덮을수 있게 된다면 혈소판의 응집을 막아 오랫동안 기능을 유지할 수 있을 것으로 생각된다.