• Tribology and Lubricants
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• 제31권2호
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• pp.62-68
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• 2015

A magnetorheological (MR) fluid is a smart material whose rheological behavior can be controlled by varying the parameters of the applied magnetic field. Because the damping force and shear force of an MR fluid can be controlled using a magnetic field, it is widely employed in many industrial applications, such as in vehicle vibration control, powertrains, high-precision grinding processes, valves, and seals. However, the characteristics of friction caused by iron particles inside the MR fluid need to be understood and improved so that it can be used in practical applications. Surface process technologies such as polytetrafluoroethylene (PTFE) coatings and diamond-like carbon (DLC) coatings are widely used to improve the surface friction properties. This study examines the friction characteristics of an MR fluid with different surface process technologies such as PTFE coatings and DLC coatings, by using a reciprocating friction tester. The coefficients of friction are in the following descending order: MR fluid without any coating, MR fluid with a DLC coating, and MR fluid with a PTFE coating. Scanning electron microscopy is used to observe the worn surfaces before and after the experiment. In addition, energy dispersive X-ray spectroscopy is used to analyze the chemical composition of the worn surface. Through a comparison of the results, the friction characteristics of the MR fluid based on the different coating technologies are analyzed.

• 한국통신학회논문지
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• 제6권1호
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• pp.45-50
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• 1981

초 저주파 변환기를 Polytetrafluoroethylene(PTFE) Film인 고체 유전재료로 만들었다. 그 실험 결과 응답은 0.1Hz에서 7,000Hz까지 $\pm$1.5dB이내이고 감도는 -60dB로 거의 일정하다. -3dB점은 0.1Hz가 되어 (상대측정) 매우 우수한 저주파 특성을 얻을 수 있었다. 상온에서 이 소자의 시정수는 60년 이상이고 활성화 에너지는 343K에서 1.1eV를 얻었다. 이 소자는 고감도 음향 통신계통이나, 지진탐사등에 이용될 수 있음이 예상된다.

• 한국컴퓨터산업교육학회:학술대회논문집
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• 한국컴퓨터산업교육학회 2003년도 제4회 종합학술대회 논문집
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• pp.49-54
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• 2003

In this work, we have seen the effect of hole-transporting layer in organic light-emitting diodes using N,N'-biphenyl-N,N'-bis-(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine(TPD) and N,N'-biphenyl-N,N'-bis-(1-naphenyl)-[1,1'-biphenyl]-4,4'-diamine(NPB). NPB is regarded as a better hole trans porting material than TPD, since it has a higher glass transition temperature$(T_g)$. And current -voltage, luminance-voltage and external quantum efficiency of device were measured with the thickness variation of buffer layer using copper phathalocyanine(CuPc) and polytetrafluoroethylene (PTFE) at room temperature. We have obtained an improvement of External quantum efficiency when the CuPc 30[nm] and PTFE 1.0[nm] is used.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권11호
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• pp.527-532
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• 2005

During the last ten years the new interruption techniques, which use the arc energy itself to increase the pressure inside a chamber by the PTFE nozzle ablation, have displaced the puffer circuit breakers due to reduced driving forces and better maintainability. In this paper, we have investigated the thermal flow characteristics inside a thermal puffer type gas circuit breaker by solving the Wavier-Stokes equations coupled with Maxwell's equations for considering all instabilities effects such as turbulence and Lorentz forces by transient arc plasmas. These relative inexpensive computer simulations might help the engineer research and design the new interrupter in order to downscale and uprating the GIS integral.

• 설비공학논문집
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• 제28권9호
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• pp.367-372
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• 2016

Gas diffusion layer (GDL) of PEMFCs plays a role that it diffuses the reactant gases to the catalyst layer on the membrane and discharge water from the catalyst layer to the channel. Physical parameters related to the mass transport of GDL are mostly from the uncompressed GDLs while actual GDLs in the assembled stacks are compressed. In this study, the relation of compression and strain of GDLs with various Polytetrafluoroethylene (PTFE) loading is measured experimentally and In-plane gas permeability is measured at the condition that the GDLs are in compressive strain. The gas permeability decreased with the loading of PTFE and the presentation of gas permeability under compressive stain is expected to improve the accuracy of modeling work of mass transport in the GDL.

• Journal of Photoscience
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• 제6권3호
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• pp.103-108
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• 1999

We present recent results on ablation mechanism, single-pulse laser micropatterning , pulsed-laser deposition(PLD) and particulates formation accompanying laser ablation, with special emplasis on polymers, in particular polymide, (PI), and polytetrafluoroethylene, (PTFE). Ablation of polymers is described on the basis of photothermal bond breaking within the bulk material. Here, we assume a first order chemical reaction, which can be described by an Arrhenius law. Ablation starts when the density of broken bonds at the surface reaches a certain critical value. Single-pulse laser ablation of polyimide shows a clear-length dependence of the threshold fluence. This experimental result strongly supports a thermal ablation model. We discuss the various possibilities and drawbacks of PLD and describe the morphology, physical properties and applications of PTFE films.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1997년도 제13회 학술발표회 논문개요집
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• pp.67-67
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• 1997

• 한국진공학회:학술대회논문집
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• 한국진공학회 1996년도 제10회 학술발표회 논문개요집
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• pp.133-133
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• 1996

• Journal of Chest Surgery
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• 제30권5호
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• pp.533-536
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• 1997

이화여자대학교 흉부외과에서는 매우 드물게 발생하는 흉부둔상에 의한 삼첨판막 역류증 환자에 있어서 mE를 사용하여 새로운 건삭을 만들어 주고 판막링을 이용하여 판막륜 성형술을 시행하여 좋은 결과를 얻었기에 보고하는 바이다. 환자는 3층 높이의 건물에서 떨어져서 응급실을 방문했으며 심에코 검사상 전유두근의 파열에 의한 심한 삼 첨판막 역류증의 소견을 보였으나 증상이 경미하여 퇴원하였다. 그러나 호흡곤란 및 심비대가 증가하여 외 상후 4개월에 수술을 시행하였으며 수술후 시행한 심에코상 삼첨판막 역류증은 보이지 않았고 호흡곤란도 사라졌다.

• 한국공간구조학회논문집
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• 제10권3호
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• pp.41-48
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• 2010

건축용 막재는 일반적으로 직포와 코팅으로 구성되며, PTFE 계열 막재는 유리섬유로 만들어진 직포에 테프론 코팅으로 구성된다. 일반적으로 PTFE 막재에 사용되는 직포에는 $\beta$-yarn이 주로 사용되며, $\beta$-yarn이 아닌 $\alpha$-yarn이 사용된 막재도 점차적으로 사용되는 시점이다. 그러나 $\alpha$-yarn으로 직조된 직포로 만들어진 건축용 막재의 특성에 관한 정보는 일반 막재에 비해 많이 부족한 편이다. 따라서 건축용 막재를 구성하는 직포를 만드는 원사의 굵기에 따른 막재의 역학적 특성에 대한 연구가 필요하다. 본 연구에서는 실험을 통하여 원사가 서로 다른 막재의 인장 특성을 비교 분석하고자 한다.