• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.125-133
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• 1998

Nine tubes with trapezoidal integral-fins having fin densities from 748 to 1654fpm and 10,30 grooves and finned tubes with caves of 0.55 and 0.64mm height respectively are tested. A plain tube having same diameter as the finned tubes is also tested for comparison. In case of condensation CFC-11 condensates at saturation state of 32$^{\circ}C$ on the outside surface cooled by inside cooling water flows. And in case of boiling the refrigerant evaporates at a saturation state of 1bar on the outside tube surface and heat is supplied by hot water which circulates inside of the tube. The tube having fin density of 1299fpm and 30grooves has the best condensation overall heat transfer coefficient. However, as far as boiling heat transfer coefficient concerns, fin tubes with cave show higher value than low fin tube having fin density of 1299fpm and 30 grooves.

• 한국화재소방학회논문지
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• 제28권4호
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• pp.14-20
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• 2014

본 연구는 인화성 액체를 특정 용기에 담유하고 구획된 공간에서 연소 실험을 실시하여 연소 패턴을 분석하는 데 있다. 담유 실험에 사용된 용기는 깊이 20 mm, 넓이 150 mm의 플라스틱이다. 화염이 착화되어 연소되는 과정은 디지털카메라(digital camera) 및 비디오카메라(video camera)를 이용하여 확보하였다. 화염이 최성기에 도달하는 속도는 벤젠이 가장 빠르고 약 60 s이다. 반면 가장 늦게 것은 알코올이었으며 약 360.0 s로 6배 정도 차이가 있었다. 화염이 최성기에 도달하였을 때 플라스틱 용기와 인화성 액체가 동시에 연소됨에 따라 연기는 대부분 검정색이었다. 연소가 완료된 후유증 검지관(crime investigation tube)을 이용하여 유증을 조사한 결과 대두유를 제외한 모든 인화성 물질에서 유증 채취가 가능했다. 즉, 연소 물질의 종류에 따라 화재의 확산 속도 및 패턴 등에 큰 차이가 있다는 것을 알 수 있었다.

• Membrane and Water Treatment
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• 제7권3호
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• pp.175-191
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• 2016

In this work, oil-in-water emulsions (O/W) were prepared successfully by membrane emulsification with $0.5{\mu}m$ pore size membrane. Sunflower oil was emulsified in aqueous Tween80 solution with a simple crossflow apparatus equipped with ceramic tube membrane. In order to increase the shear-stress near the membrane wall, a helical-shaped reducer was installed within the lumen side of the tube membrane. This method allows the reduction of continuous phase flow and the increase of dispersed phase flux, for cost effective production. Results were compared with the conventional cross-flow membrane emulsification method. Monodisperse O/W emulsions were obtained using tubular membrane with droplet size in the range $3.3-4.6{\mu}m$ corresponded to the membrane pore diameter of $0.5{\mu}m$. The final aim of this study is to obtain O/W emulsions by simple membrane emulsification method without reducer and compare the results obtained by membrane equipped with helix shaped reducer. To indicate the results statistical methods, $3^p$ type full factorial experimental designs were evaluated, using software called STATISTICA. For prediction of the flux, droplet size and PDI a mathematical model was set up which can describe well the dependent variables in the studied range, namely the run of the flux and the mean droplet diameter and the effects of operating parameters. The results suggested that polynomial model is adequate for representation of selected responses.

• Journal of Advanced Marine Engineering and Technology
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• 제27권7호
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• pp.879-888
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• 2003

Swirling air flow in a horizontal round tube was experimentally studied for its visualization. The present investigation deals with swirl angle, flow visualization studies and accompanying vortex core behavior by using oil smoke and a hot wire anemometer for Re = 40,000 and 50000 at X/D = 41, 59 and 71. In the swirl air flow, a vortex core was formed at high swirl intensity along the test tube. The swirl angle and the vortex core depended on the swirl intensity along the test tube. The results of swirl angles measured by flow visualization and hot wire reasonably agree with those of previous studies.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.597-600
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• 2001

In order to investigate the electrical properties of X-ray tube oils for insulating and cooling, the breakdown characteristics in temperature range of $20\sim100[^{\circ}C]$, that of AC breakdown in 0.5~2.5[mm] of gap length, we are made researches. The classification for the physical properties of oil for X-ray tube by FTIR and H-NMR experiments was confirmed to type of mineral oils. As for the dependance of breakdown characteristics due to electrode gap length, breakdown voltage was found nearly uniform by impurity effect according to the increase of gap. As a result the characteristics for AC breakdown, the dielectric strength was increased to $90[^{\circ}C]$ but decreased over $90[^{\circ}C]$ in the temperature range.

• 한국공작기계학회논문집
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• 제14권5호
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• pp.49-54
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• 2005

An experimental Investigation was performed to study the characteristics of Electro-Rheological fluid flow in a horizontal rectangular tube with or without D.C electric field control. First, the microscopic behavior of the ER suspension structure between rectangular tube brass electrodes for the stationary ER nut(i and flow of the ER fluid was investigated by flow visualization. The flow of the ER fluid between fluid rectangular tube was solved experimental using the constitutive equation for a Bingham fluid. ER fluid is made silicon oil mixed with $0.2wt\%$ starch having hydrous particles. Velocity distributions of the ER fluids were obtained by particle image velocimetry measuring those of the clusters using an image processing technique.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.597-600
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• 2001

In order to investigate the electrical properties of X-ray tube oils for insulating and cooling, the breakdown characteristics in temperature range of 20∼100[$^{\circ}C$], that of AC breakdown in 0.5∼2.5(mm) of gap length, we are made researches. The classification for the physical properties of oil for X-ray tube by FTIR and $^1$H-NMR experiments was confirmed to type of mineral oils. As for the dependance of breakdown characteristics due to electrode gap length, breakdown voltage was found nearly uniform by impurity effect according to the increase of gap. As a result the characteristics for AC breakdown, the dielectric strength was increased to 90[$^{\circ}C$] but decreased over 90[$^{\circ}C$] in the temperature range.

• 소성∙가공
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• 제13권5호
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• pp.403-408
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• 2004

Hydroformability of 6061 and 7075 aluminum tube materials was studied by warm hydroforming experiments. A special tooling and heating system was designed and manufactured in order to perform warm hydroforming between room temperature and $300^{\circ}C$. The control of tube temperature for warm hydroforming was made by the control of temperature of oil medium. Warm hydroformability was analyzed by tube appearances, tube elongation and hardness values. Hydroforming characteristics of 6061 and 7075 tubes showed different temperature dependence between room temperature and $300^{\circ}C$. The difference in hydroformabilities of 6061 and 7075 at elevated temperatures was interpreted by the different sensitivity to dynamic strain aging of both aluminum materials.

• 청정기술
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• 제24권4호
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• pp.365-370
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• 2018

Oil shale은 kerogen을 함유한 퇴적암으로 대표적인 비재래 에너지자원으로 알려져 있다. 열분해 공정을 통하여 oil shale이 분해되면 oil, gas 및 coke를 생성하게 된다. 본 연구에서는 oil shale의 청정 전환기술을 개발하기 위하여 oil shale의 TGA 및 연속 열분해 연구를 수행하였다. Oil shale의 열분해 전환율에 대한 반응 온도 및 체류시간의 영향을 살펴보고 oil의 생성율을 살펴보았다. Oil shale의 열분해 전환율은 온도와 체류시간에 따라 증가하였으며 $450{\sim}500^{\circ}C$, 체류시간 30 min의 조건에서 최대 oil 생산 수율을 나타내었다.

• 한국염색가공학회지
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• 제23권3호
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• pp.210-218
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• 2011

The structure of kapok fiber was characterized using FTIR and $^{13}C$-NMR spectrometers, elemental analyzer, x-ray diffractometer, SEM and IMT I-Solution ver 7.5. The kapok has a hollow tube shape and is composed of cellulose I with crystallinity of 47.95%. To develop novel oil-sorbent materials necessary to avoid the environmental pollution by spilled oil, the oil absorption capacity of various fibers such as kapok, polypropylene(PP), acryl, bamboo, cotton, rayon and wool fibers is compared in this study. The kapok fiber had the highest oil absorption capacity among the fibers and its water absorption capacity was the least. The kapok fiber selectively absorbed significant amounts of oils (43g/g of fiber for kerosene, 65g/g of fiber for soybean oil), which might be due to higher hydrophobicity of the kapok fiber, suggesting that kapok fiber may have high potential as excellent oil-absorbent materials.