• 한국방재학회 논문집
• /
• 제4권2호
• /
• pp.53-59
• /
• 2004

본 연구는 집중호우 시에 발생하는 맨홀뚜껑의 비산(飛散)현상의 원인을 수리모형과 수치모형(SWMM)을 사용하여 밝힌 연구이다. 대규모 간선에서 써차지 흐름의 급격한 수두상승 현상에 대해 수치모형과 수리모형 결과가 매우 잘 일치하였다. 맨홀 뚜껑이 비산 하는 현상의 원인은 펌프장의 게이트 조작이나 간선의 막힘 등으로 발생하는 써차지 흐름에 따른 압력전파에 의해 기인하는 맨홀 내 잔존 압축공기괴의 맨홀에서의 팽창 분출에 의한 것으로 나타났다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
• /
• pp.1192-1195
• /
• 2003

A highly condensed ozone gas be transferred to the superconductor thin film growth chamber because ozone is strong oxidizing gas. In order to obtain high quality oxide thin films, higher ozone concentration is necessary. In this paper an ozone condensation system was evaluated from the viewpoint of an ozone supplier for oxide thin film growth. Ozone was condensed by an adsorption method and the ozone concentration reached 8.5 mol% in 2.5 h after the beginning of the ozone condensation process, indicating high effectiveness of the condensation process. Ozone was continuously desorbed from the silica gel by the negative pressure.

• International Journal of Aeronautical and Space Sciences
• /
• 제9권2호
• /
• pp.98-106
• /
• 2008

The motive gas of a supersonic ejector is supplied from different sources depending on the application. The performance of an ejector that is represented by the secondary flow pressure, starting and unstarting pressures heavily depends on the molecular properties of the motive gas. The effects of specific heat ratio of the motive gas were investigated experimentally for an axi-symmetric annular injection type supersonic ejector. Both the starting pressure and unstarting pressure, however, decreased with the increase of the specific heat ratio of the motive gas. It was discovered that the secondary flow pressure increased as the specific heat ratio of the motive gas decreased even if the stagnation pressure of the motive flow was invariant. However, when the motive gas flow nozzle area ratio is large enough for the motive gas to be condensed, different tendency was observed.

• 한국광학회지
• /
• 제24권5호
• /
• pp.279-286
• /
• 2013

Brillouin spectroscopy has been widely used for the investigation of acoustic properties of condensed matters in the hypersonic region. A high-pressure Brillouin spectrometer was set up by combining a diamond anvil cell and a tandem multi-pass Fabry-Perot interferometer. It was successfully applied to liquid ethanol, and the pressure dependence of the sound velocity, the refractive index and other acoustic properties were derived based on the measurements. The detailed optical setup and experimental procedure are described.

• Elastomers and Composites
• /
• 제33권2호
• /
• pp.103-109
• /
• 1998

The determination method of successful operation conditions to control the temperature and pressure in autoclave after non-taping vulcanization process was represented. Heat and mass balances were constructed to predict the mass flow rates of air, steam, and condensed water into or from autoclave when the temperature and pressure in the autoclave were to be controlled in the desired profiles. The balance equations were solved by appropriate mathematics, and the solution was applied to an autoclave system where the temperature and pressure were linearly decreased. The resulting solutions were illustrated in graphs.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.157.2-157.2
• /
• 2016

Water repellent surfaces may enhance the condensation by efficiently removing the condensed droplets. However, such surfaces may lose their original performance as they are exposed to external mechanical stresses. In this work, we fabricated spray-coated mechanically robust superhydrophobic surfaces using treated titanium dioxide (Type 1) or silica particles (Type 2). Then we compared the mechanical robustness of such surfaces with the silane-coated superhydrophobic surface and PEEK coated surface using a controlled-sand blasting method. The results show that the spray-coated samples can maintain the same level of the contact angle hysteresis than silane-coated superhydorphobic surface after sand blasting at 2 bar. The spray-coating method was applied to the tube type condenser and the condensation behaviors were observed within the environmental chamber with controlled pressure, humidity and non-condensable gas. Previously-reported droplet jumping was observed in the early stage of the condensation event, but soon the droplet jumping stopped and only dropwise condensation was observed since the condensed droplets were pinned on the cracks at spray-coated surfaces. The static contact angle decreases from $158.0^{\circ}$ to $133.2^{\circ}$, and hysteresis increases from $3.0^{\circ}$ to $23.5^{\circ}$ when active condensation occurs on such surfaces. This work suggests the benefits and limitation of spray-coated superhydrophobic condensers and help develop advanced condensers for practical use.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2003년도 춘계종합학술대회
• /
• pp.590-593
• /
• 2003

금속 산화물 박막 제작에 유효한 산화가스로 오존가스를 채택했다. 고품질의 산화 박막을 얻기 위해 고농도 오존이 필요하여 오존 농축 시스템을 구축 및 평가하였다. 이 장치는 실리카겔로 오존의 선택 흡착을 이용해, 농축 공정 시작 후 유입 농도 8.5 mol%가 검출되는 2.5 h에서 농축이 완료되고, 진공 배기로 고농도 오존가스를 생성하였으며, 성막 장치까지 가스가 공급되는 몇 분 동안은 자연분해 효과를 무시할 수 있었다.

• Journal of Mechanical Science and Technology
• /
• 제16권5호
• /
• pp.696-702
• /
• 2002

In the present paper, the effects of inlet pressure on the heat and mass transfer rates of an air cooler are numerically predicted by a local analysis method. The pressures of the moist air vary from 2 to 4 bars. The psychrometric properties such as dew point temperature, relative humidity and humidity ratio are employed to treat the condensing water vapor in the moist air when the surface temperatures are dropped below the dew point. The effects of the inlet pressures on the heat transfer rate, the dew point temperature, the rate of condensed water, the outlet temperature of air and cooling water are calculated. The condensation process of water vapor is discussed in detail. The results of present calculations are compared with the test data and shows good agreements.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1996년도 추계학술대회 논문집
• /
• pp.147-151
• /
• 1996

Brewster angle microscopy(BAM) makes it possible to observe the monolayer states on the water subphase and the phase transitions from a gaseous phase via a expanded phase to a condensed phase. Also BAM can be used to observe the films on the solid substrate such as Langmuir-Blodgett(LB) films. In this Paper Polyamic Acid Alkylamine Salts(PAAS) was used for forming L films and LB films and $\pi$-A isotherm showed pressure of each phase. We obtained BAM images as surface pressure increased. Images of LB films were compared with data from ellipsometry which was used to measure the film thickness. Images of both L films and LB films were analyzed with computer in the point of brightness.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
• /
• pp.537-538
• /
• 2006

BSCCO thin films have been fabricated by epitaxy growth at an ultra-low growth rate. The growth rates of the films was set in the region from 0.17 to 0.27 nm/min. MgO(100) was used as a substrate. In order to appreciate stable existing region of Bi 2212 phase with temperature and ozone pressure, the substrate temperature was varied between 650 and $720^{\circ}C$ and the highly condensed ozone gas pressure ($PO_3$) in vacuum chamber was varied between $2.0{\times}10^{-6}$ and $2.3{\times}10^{-5}\;Torr$.