• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.113-114
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• 2002

Radial, tilting 12-pad proceeding bearings are applied as the radial bearings of vertical rotors of water turbines. The mean loads are stable at the peripheral speeds of proceeding reaching 50 m/s. The operation of tilting 12-pads proceeding bearing has been introduced at the assumption of adiabatic oil film. The oil film pressure, temperature and viscosity distributions have been obtained by iterative solution of the Reynolds', energy and viscosity equations. The resulting oil film force, minimum oil film thickness, power loss, oil flow, maximum oil film pressure, maximum temperature have been computed for different load angle of bearing.

• 통합자연과학논문집
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• 제3권4호
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• pp.219-225
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• 2010

On the surface of mesoporous silica thin films (MSTF) which were fabricated by sol-gel approach there are existences of water and three different silanol types including chained, germinal and isolated silanol. Their amounts changes as a function of aging time of used sol solution, as confirmed by FT-IR. The adsorbed water generates ionic carriers such as H+ and OH- and passivates the Si dangling bonds at the interface of silicon wafer-MSTF. The ionic carriers can not only transport across the thickness of thin film to enhance the leakage current but also diffuse toward the silicon wafer-MSTF interface to depassivate Si dangling bonds. On the other hand, chained silanols or germinal silanols promote the moisture adsorption of MSTF and tend to form strongly hydrogen bonded systems with adsorbed water molecules resulting in very high dielectric constant. Isolated silanol, on the contrary, affects less on electrical properties of thin film.

• 공업화학
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• 제23권2호
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• pp.217-221
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• 2012

에틸렌-아크릴산 공중합체(EAA)를 물에 분산시킨 후, 폴리(비닐 알코올) (PVA) 수용액과 블렌딩하여 내수성 및 차단성이 향상된 필름을 제조하였다. EAA의 함량에 따라 제조된 필름으로 열적-기계적 성질, 접촉각, 수분 투과율, 산소 투과율을 측정하였고 내수성에 대한 평가 실험도 진행하였다. 필름의 인장강도는 $9.16{\sim}11.75\;kg/mm^2$으로 PVA와 큰 차이가 없었으며, 경도의 경우는 EAA 함량에 따라 값이 점점 증가하였다. 유리전이 온도와 용융 온도는 약간 향상되었다. PVA/EAA의 비율이 90/10인 블렌딩 필름의 경우 Swelling 109%, Solubility 0%로 측정되어 PVA에 비하여 내수성이 개선되었음을 확인할 수 있었다. 또한, PVA/EAA의 비율이 90/10인 블렌딩 필름(두께 $2.5\;{\mu}m$)을 PET 필름(두께 $50\;{\mu}m$) 위에 코팅하여 제조된 필름의 수분투과율과 산소 투과율은 각각 $9.1\;g/m^2/day$과 $2.0\;cc/m^2/day$으로 측정되었다.

• Tribology and Lubricants
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• 제2권2호
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• pp.27-31
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• 1986

By Bong Goo Rhee, College of Engineering, The Univ. of Won Kwang (344-2, Sinyongdong, Iri-shi, 510 Chunpuk-do, Korea), Yoshitsugu Kimura and Kazumi Okada, Institute of Interdisciplinary Research, Faculty of Engineering, The Univ. of Tokyo(4-6-1 Komaba, Meguro-ku, Tokyo 153, Japan), Katsuyuki Hashizume, Taiho Kogyo(2-47 Hosoya-Cho, Toyoda-Shi 471, Japan) and Chang Heon Chi, The G. S of Chon buk N. Unv. It is empirically known that, in concentrated conjunctions lubricated with O/W emulsions, only the oil is entrained to form elastohydrodynamic films. In the present work, this phenomenon is studied experimentally and the result is compared with a theory Which employes a starved lubrication concept. The experiment is conducted in a four roller machine with 0/W emulsions of varying concentration of oil, i.e. beef tallow, in which the film thickness is determined by detecting the rate of X-ray transmission through the conjunction. Excellent agreement is found between the experimental and the theoretical results.

• 한국정밀공학회지
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• 제27권2호
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• pp.29-33
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• 2010

We have investigated fs-laser ablation as well as optoperforation threshold of PDMS (Polydimethylsiloxane) thin lid cover on ${\mu}$-channel with changing the flow medium from water to hemoglobin. The ablation threshold is found to be independent of both PDMS thin film thickness and flow medium, but the optoperforation threshold is dependent on the films thickness. The observation that the ablation process is well described with simple two-temperature model supposed that the cover lid PDMS of $\mu$-channel be processed with minimized thermal effects by fs-laser with low laser fluence.

• 약학회지
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• 제33권6호
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• pp.324-332
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• 1989

Drug release from sulfanilamide granules coated with a polyelectrlyte complex of sodium tripolyphosphate and chitosan was studied. The coating film thickness increased with increasing concentration of chitosan in the coating solution and the drug release rates of the coated granules were significantly reduced comparing with those of the uncoated granules. $T_{50%}$ of the uncoated granules was 6 minutes, but those of the granules coated with chitosan-sodium tripolyphosphate from 0.5, 0.7, and 0.9% (w/v) chitosan-HCl solution were 27, 135, and 180 minutes, respectively in distilled water. In dissolution medium at pH 6.8, $T_{50%}$ of the uncoated granules was 4 minutes, but those of the granules coated with chitosan-sodium tripolyphosphate from 0.5, 0.7, and 0.9(w/v)% chitosan-HCl solution, were 32, 135, and 160 minutes, respectively.

• Journal of Advanced Marine Engineering and Technology
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• 제30권4호
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• pp.483-493
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• 2006

A model for a pressure drop of water vapor flow across tube banks in a horizontal tube absorber of an absorption chiller/heater using LiBr solution as a working fluid has been developed based on a commercial 20RT(70kW) absorption chiller/heater. The numerical results show that the characteristic of the pressure drop in the shell side of the horizontal tube absorber is completely different from that in a conventional shell and tube heat exchanger. Especially, solution film thickness has significant influence on the vapor pressure drop in the horizontal tube absorber. In addition, the effects by the tube diameters, the longitudinal pitch to diameter ratio, and Reynolds number of the vapor flow, on the vapor pressure drop have been studied to evaluate the compactness of tube absorber. It was found that the vapor pressure drop decreases as tube diameter increases, the longitudinal pitch to diameter ratio increases, and Reynolds number of the vapor flow decreases. A comparison of the present study results with well-established experimental and numerical results showed a good overall agreement.

• 대한기계학회논문집
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• 제10권1호
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• pp.86-95
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• 1986

본 연구에서는 폭이 일정한 급경사 개수노상(0.15mW*1.6mL)을 상온의 물이 유동할 때 유동율과 수로 급경사에 따른 명입치에서의 유동깊이 변화를 실측을 통하여 밝히고 이념치와 비교하였다.

• 한국수소및신에너지학회논문집
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• 제16권2호
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• pp.130-135
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• 2005

Cadmium selenide is one of the group IIb-VI compounds, which is the promising semiconductor material due to its wide range of technological applications in optoelectronic devices such as photoelectrochemical cells, solid state solar cells, thin film photoconductors etc. CdSe has optical band gap of 1.7-1.8eV and proper conduction band edge for water splitting. CdSe films are coated with small thickness(20-50nm) nanocrystalline $TiO_2$ film by electrodeposition or chemical bath deposition methods and PEC properties of CdSe and CdSe/$TiO_2$ sandwich structure are studied. The photoactivity of CdSe and CdSe/$TiO_2$ films deposited on titanium substrate is studied in aqueous electrolyte of 1M NaOH solution. Photocurrent and photovoltage obtained were of the order of 2-4 mA/$cm^2$ and 0.5V, respectively, under the intensity of illumination of 100 mW/$cm^2$.

• 한국지역사회생활과학회지
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• 제15권2호
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• pp.179-187
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• 2004

The purpose of this study is to investigate the preservation of traditional sesame dasik when stored in different packaging material by comparing its physical and sensorial characteristics. The quality and sensory characteristics of sesame dasik that were evaluated were moisture content, water activity, number of microflora, texture profile, Hunter color different value, and sensory properties (color, chewiness, overall acceptability, etc) during the storage at 35\pm1^\circ{C}$ temperature and $73\pm{2%}$ relative humidity. And the packaging materials were paper boxes (coated 0.02mm thickness polyethylene film), plastic boxes, and oriented polypropylene laminated film. Traditional sesame dasik is made from sesame powder 100g, honey 25g, rice syrup 25g, and table salt 0.5g. During the storage period, the changes in water content and water activity of sesame dasik with different packaging material showed a slight decline. On the other hand, it increased in hardness, and "a" and "b" value of Hunter color difference during the storage. Texture profile analysis data change in hardness was the greatest after the third day in a paper box, and it was affected by the moisture content of dasik and the temperature and relative humidity of the air. Therefore plastic boxes or oriented polypropylene laminated film was found to be better suited than paper boxes for storing sesame dasik.