• Title/Summary/Keyword: Build-up film

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Effects of Distance between Pads on the Film Pressure in Pad Bearings (패드 베어링에서 패드사이의 거리가 유막압력에 미치는 영향)

  • Kim, Jong-Soo;Kim, Kyung-Woong
    • Tribology and Lubricants
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    • v.13 no.1
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    • pp.53-61
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    • 1997
  • Experiments are conducted to investigate the effects of distance between pads on the film pressure and the inlet pressure build-up at the entrance of pad bearings. The inlet pressure and the film pressure are measured by manometers in several cases of the distance between pads. The experimental results are also compared with the theoretical results which are calculated using the several methods for the estimation of the inlet pressure. In the experimental results , the distance between pads has a large influence on the film pressure and the inlet pressure build-up a bearing entrance. It is also shown that the effects of the inlet pressure on the film pressure are remarkable, although inertia parameter is a little higher (${\ge}0.05$).

Effects of inlet pressure build-up on the running characteristics of tilting pad thrust bearing (선단압력이 틸팅 패드 추력베어링의 운전특성에 미치는 영향)

  • 이경우;김종수
    • Journal of Advanced Marine Engineering and Technology
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    • v.22 no.1
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    • pp.85-91
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    • 1998
  • In this paper, an influence of inlet pressure on the running characteristics of tilting pad thrust bearing is studied by a numerical analysis. The inlet pressure is obtained from the extended Bernoulli equation including the loss coefficient which is varied with the operating conditions. The running characteristic parameters such as the minimum film thickness, the film pressure and the film thickness ratios are calculated for various runner speeds with constant load in particular two pivot positions. The results are shown that the inlet pressure has a large influence on the minimum film thickness and other running characteristic parameters.

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Development of Medical Picture Archiving and Communication System (의료용 화상정보의 저장 및 전송 시스템 개발)

  • 이태수;백승권
    • Journal of Biomedical Engineering Research
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    • v.9 no.2
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    • pp.195-210
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    • 1988
  • We build up distributed database of medical picture and design and realize H/W & S/W of special image workstation. We build up high speed image transmission system for distributed database and retrieval of various medical pictures in w ard through image transmission system and realize integrated image diagnosis. This system improves medical service by speedy diagnosis and enables more precise diagnosis by integrated image diagnosis through distributed database. In economical view this system curtails huge cost of film processing and transmission, which make medical expense cheaf, because it does not use film. We built up PACS in pediatric hospital of Seoul National University Hopital and tested the system with various medical pictures and showed that speedy integrated image diagnosis is possible.

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Kinetic Theory Analysis for Thin-Film Bearings (기체분자운동론을 이용한 박막 베어링 해석)

  • Chung Chan Hong
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2004.11a
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    • pp.162-170
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    • 2004
  • A kinetic theory analysis is used to study the ultra-thin gas flow field in gas slider hearings. The Boltzmann equation simplified by a collision model is solved by means of a finite difference approximation with the discrete ordinate method. Calculations are made for the flow field inside stepped and straight slider bearings. The results are compared well with those from the DSMC method. Special attention has been paid to the effect of the pressure build-up in front of a hearing, which has never been assessed before. It has been shown that the pressure build-up at the inlet is about $4.5\%$ of the operating pressure and the resulting load capacity is about $25\%$ higher for the case considered in the present study.

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Dyeing Properties of Polyurethane-impregnated PET Knit

  • Park, Jong-Ho;Kim, Sung-Dong
    • Textile Coloration and Finishing
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    • v.20 no.5
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    • pp.35-40
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    • 2008
  • Dyeing and washing fastness properties of polyurethane-impregnated polyester (PU-impregnated PET), and the distribution of two disperse dyes between PET and PU film were studied to investigate the effect of PU portion to exhaustion and washing fastness. Dyeing properties of PU-impregnated PET were quite different with those of PET: PU-impregnated PET absorbed disperse dye linearly from the early stage of dyeing to equilibrium, and it exhibited excellent build-up property up to 4 %owf dyeing. The absorbed dye on PU film at early dyeing stage migrated to more substantive PET at the temperature higher than $115^{\circ}C$. The amount of exhausted dye on PET portion was larger than on PU film and the distribution ratio was $2.08{\sim}2.34$. The grade of washing fastness of PU-impregnated PET was the same as or lower by $0.5{\sim}1$ grade than PU film whose washing fastness was lower by $0.5{\sim}1$ than PET.

Experimental Investigation on the Inlet Pressure Build-Up at the Entrance of a Large Tilting Pad Journal Bearing (대형 틸팅패드 저어널베어링의 패드 입구에서 발생하는 선단압력에 관한 실험적 연구)

  • 하현천;김경우;김영춘;김호종
    • Tribology and Lubricants
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    • v.9 no.2
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    • pp.22-28
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    • 1993
  • The experimental investigation on the inlet pressure of a large tilting pad journal bearing is studied. The continuous distribution of the film pressure and film thickness are measured along with the shaft speed and bearing load for various flow rates. Considerably large inlet pressure is observed at the entrance of each pad, especially lower pads. The inlet pressure increases with the increase of shaft speed as well as bearing load, but it is almost independent on the folw rate and the oil supply temperature. Because of the inlet pressure, the upper pads always keep up slight wedge film shape which are almost parallel to the journal surface, and spragging is not observed in the upper pads with no preload.

BCB Polymer Dielectrics for Electronic Packaging and Build-up Board Applications

  • Im, Jang-hi;Phil-Garrou;Jeff-Yang;Kaoru-Ohba;Masahiko-Kohno;Eugene-Chuang;Jung, Moon-Soo
    • Proceedings of the International Microelectronics And Packaging Society Conference
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    • 2000.04a
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    • pp.19-25
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    • 2000
  • Dielectric polymer films produced from benzocyclobutene (BCB) formulations (CYCLOTENE* family resins) are known to possess many desirable properties for microelectronic applications; for example, low dielectric constant and dissipation factor, low moisture absorption, rapid curing on hot plate without reaction by-products, minimum shrinkage in curing process, and no Cu migration issues. Recently, BCB-based products for thick film applications have been developed, which exhibited excellent dissipation factor and dielectric constant well into the GHz range, 0.002 and 2.50, respectively. Derived from these properties, the applications are developed in: bumping/wafer level packaging, Ga/As chip ILD, optical waveguide, flat panel display, and lately in BCB-coated Cu foil for build-up board. In this paper, we review the relevant properties of BCB, then the application areas in bumping/wafer level packaging and BCB-coated Cu foil for build-up board.

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A Study on Dose Distribution of Electron Beams by Semiconductor Detector (반도체 검출기에 의한 전자선 선량분포에 관한 연구)

  • Kang, Wee-Saing;Ha, Sung-Whan;Park, Charn-Il
    • Journal of Radiation Protection and Research
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    • v.9 no.1
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    • pp.19-25
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    • 1984
  • There is not yet an universal method of electron dosimetry. The Authors measured dose distributions of the electron beams from Clinac-18 by means of silicon detector connected to X-Y recorder, and compared them in water phantom with dose distributions measured by film and ion chamber, both inserted in polystyrene phantom. The results are as followings, 1. Dose in build-up region increased with the field size for all energy, and depth dose profiles of $6{\sim}12MeV$ beam under the depth of maximum dose were independent of field size, but those of 15 and 18 MeV beam were dependent on the field size. 2. The widths of penumbra by semiconductor detector were narrower than those by film for same energy beam. 3. Depth dose profiles by three different dosimeter did not coincide each other. In the build-up region, dose by semiconductor detector was lower than that by any other dosimeter.

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