• Korea-Australia Rheology Journal
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• 제16권4호
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• pp.227-233
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• 2004

Simplified model of slide-fed curtain coating flow has been developed and tested in this study. It rests on the sheet profile equations for curtain thickness in curtain flow and its trajectory derived by the integral momentum balance approach of Higgins and Scriven (1979) and Kistler (1983). It also draws on the film profile equation of film thickness variation in flow down a slide. The equations have been solved in finite difference approximation by Newton iteration with continuation. The results show that how inertia (Rey­nolds number), surface tension (capillary number), inclination angle of the slide, and air pressure difference across the curtain affect sheet trajectory and thickness profile. It has been revealed that approximate models can be useful to easily analyze coating flow dynamics without complex computations, giving qualitative agreement with full theory and with experiment.

• 한국대기환경학회지
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• 제27권5호
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• pp.614-622
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• 2011

In this study, a new tunnel ventilation method with a high velocity air curtain flow has been investigated for improving the ventilation exhaust efficiency and removing air pollutants in subway tunnels. At upper or lower position right downstream of a main duct connected with a ventilation opening, air curtain flows were suppled into the main duct where the air flow velocity was in the range of 2~6 m/s. Exhaust efficiency was monitored for both cases with and without air curtain flow for different air velocities, locations and injection angles of the air curtain. Particulate matter concentrations (PM10, PM2.5 and PM1.0) were also checked at both the main duct and ventilation opening before and after supplying air curtain flows. Lower air velocity of the main duct flow, higher air velocity of the air curtain led to higher exhaust efficiency and the air curtain condition of 30..inclined injection toward the main flow showed the maximum exhaust efficiency. The exhaust efficiency of about 24% without the air curtain could be improved to about 34% after using the air curtain flow. PM concentration decreased at the main duct and increased at the ventilation opening after using the air curtain flow. Therefore, the suggested method to use air curtain flows in tunnels will be probably one of the promising tools to reduce air pollutants in subway tunnels.

• 생물환경조절학회지
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• 제25권4호
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• pp.270-276
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• 2016

This study analysed overall heat transfer coefficient, heat transmission, and rate of indoor air heating provided by water curtain in order to determine the heat transfer characteristic of double-layered greenhouse equipped with a water curtain system. The air temperatures between the inner and outer layers were determined by the water flow rate and inlet water temperature. Higher water flow rate and inlet water temperature resulted in the increased overall heat transfer coefficient between indoor greenhouse air and water curtain. However, it was found that with higher levels of water flow rate and inlet water temperature, indoor overall heat transfer coefficient was converged about $10W{\cdot}m^{-2}{\cdot}^oC^{-1}$. The low correlation of overall heat transfer coefficient between water curtain and air within double layers was likely because the combination of greenhouse shape, wind speed and outdoor air temperature as well as water curtain affected the heat transfer characteristics. As water flow rate and inlet water temperature increased, the heat transferred into the greenhouse by water curtain also tend to rise. However it was demonstrated that the rate of heat transmission from water curtain into greenhouse with water curtain system using underground water was accounted for 22% to 28% for total heat lost by water curtain. The results of this study which quantify heat transfer coefficient and net heat transfer from water curtain may be a good reference for economical design of water curtain system.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2006년도 추계학술대회 논문집
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• pp.17-20
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• 2006

Passenger safety is fundamental factor in automobile. Among much equipment for passenger safety, the air bag system is the most fundamental and effective device. Beside of the front air bag system which installed on most of all automobiles, a curtain-type air bag is increasingly adapted in deluxe cars fur protecting passengers from the danger of side clash. Curtain type airbag system consists of inflator housing, fill hose, curtain airbag. Inflator housing is a main part of the curtain-type air bag system for supplying high-pressure gases to deploy the air bag-curtain. Fill hose is a passageway to carry the gases from inflator housing to each part of curtain airbag. Therefore, it is very important to design the vent holes of fill hose for good performance of airbag deployment. But, the flow information from vent holes of fill hose is very limited. In this study, we measured instantaneous velocity fields of a high-speed flow ejecting from the vent holes of fill hose using a dynamic PIV system. From the velocity Held data measured at a high frame-rate, we evaluated the variation of the mass flow rate with time. From the instantaneous velocity fields of flow ejecting from the vent holes in the initial stage, we can see a flow pattern of wavy motion and fluctuation. The flow ejecting from the vent holes was found to have very high velocity fluctuations and the maximum velocity was about 480m/s at 4-vent hole region. From the mass flow rate with time, the accumulated flow of 4-vent hole has occupied about 70% of total flow rate.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.407-408
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• 2006

Passenger safety is one of the most important considerations in the purchase of an automobile. A curtain-type air bag is increasingly adapted in deluxe cars for protecting passengers from the danger of side clash. Inflator housing is a main part of the curtain-type air bag system for supplying high-pressure gases to pump up the air bag-curtain. Although the inflator housing is fundamental in designing a curtain-type air bag system, flow information on the inflator housing is very limited. In this study, we measured instantaneous velocity fields of a high-speed flow ejecting from the inflator housing using a dynamic PIV system. From the velocity field data measured at a high frame-rate, we evaluated the variation of the mass flow rate with time. From the instantaneous velocity fields of flow ejecting from the airbag inflator housing in the initial stage, we can see a flow pattern of broken shock wave front and its downward propagation. The flow ejecting from the inflator housing was found to have large velocity fluctuations and the maximum velocity was about 700m/s. The velocity of high-speed flow was decreased rapidly and the duration of high-speed flow over 400m/s was maintained only to 30ms. After 100ms, there was no perceptible flow.

• 한국산학기술학회논문지
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• 제13권6호
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• pp.2773-2778
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• 2012

콘크리트댐 하부지반에서의 침투시 유선망 특성을 파악하고자 다양한 흐름조건에 대하여 유한차분식을 정식화하고 해석에 적용하였다. 댐하부에 차수벽이 없는 경우 불균질 지반에서의 등수두선에 있어서는 투수계수가 상대적으로 큰 영역에서 등수두선의 경사가 크게 된다. 댐하부지반의 좌측에서 우측으로의 침투에 있어 차수벽을 댐의 중앙 하부와 좌측 끝단 하부에 설치하는 경우에 대하여 침투해석을 실시하였다. 해석결과를 통해 볼 때 하류측 차수벽면을 따르는 흐름에 있어 차수벽을 좌측에 설치한 경우의 유속이 차수벽을 중앙에 설치한 경우의 유속에 비하여 감소함을 알 수 있고 차수벽 우측지반내의 흐름에 있어서는 차수벽을 좌측에 설치한 경우의 유선이 상대적으로 수평선에 가깝다.

• 설비공학논문집
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• 제28권7호
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• pp.269-274
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• 2016

This paper aims to suggest the water curtain installation guideline for prevention of fire spread. The water curtain systems play a role in preventing fire spread which is caused by fire flames and radiation heat release from a fire source. The radiation attenuation ratio is affected by the water droplet size, vertical distance from the nozzle and flow rate. This study suggests the water curtain installation guideline as follows : (1) Investigation of a reference store array (2) Calculation of the number of drencher heads (3) Review of the relationship between droplet size and attenuation factor depending on the height of the drencher head (4) Review of a drencher head array and spray overlapping. The reference traditional market in which a fire compartment is installed using a water curtain can be predicted to have a radiation attenuation ratio of 50%.

• 한국분무공학회지
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• 제22권1호
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• pp.13-21
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• 2017

The fog screen is a device projecting the media to the aerosol flow field. As major parameters to generate dense and steady fog screen, shear stress, optical blockage ratio and SMD were obtained result through experiment. The micro droplet was generated by the piezo oscillation element, and the aerosol flow mixed with an air flow was sprayed into the vertical direction from the top of the fog screen through the 280 mm slot. For produce a dense, uniform fog screen, the shear effect, optical blockage ratio and SMD between aerosol and air curtain were measured. The minimum and maximum shear stress conditions were selected and it was confirmed that the optical transmission deviation of the aerosol flow field was small when the aerosol and air curtain flow rates were changed. When the aerosol and air curtain flow power were 18 V (1.51 m/s) and 24 V (2.55 m/s), respectively, under the condition of the minimum shear stress and laminar flow, the optical blockage ratios with the spray length were small, and it produced a most stable and high density uniform fog screen by injecting a constant of $10{\mu}m$ or less.

• 국제학술발표논문집
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• The 1th International Conference on Construction Engineering and Project Management
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• pp.1022-1027
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• 2005

This research presents a collaborative supply chain management system for curtain walls using Radio Frequency IDentification (RFID) to track the product and information flow among participants in high-rise building construction projects. This resarch developed a process model and a strategy for effective utilization of RFID technology through the curtain wall life-cycle. Then an information management system was developed to support the supply chain management of curtain walls with incorporating RFID into curtain wall products flow throughout the life-cycle. The system has been tested for validation and verification in a real world project.

• 한국대기환경학회지
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• 제16권2호
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• pp.129-140
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• 2000

Simulation study has been carried out to analyze the air flow supplying from the heat pump system inside the tollgate booth by using the Phoenix computer simulation program. Through this simulation analysis we can find the problem of present tollgate booth in terms of air flow and recommend an improved model also simulate this model. Final results as follows; It was turned out that the fresh air conditioning is not provided to the worker effectively due to the improper location of inlet and outlet in the present tollgate booth in addition to that the air curtain system applied in the booth lowered air circulation from outside. The improved model was suggested first to increase the air curtain effect by downsizing the window and by installation of the air curtain suction line to reduce the induced outdoor air second to supply the fresh air to the worker directly by relocation of the inlet and outlet of supplying air. With these improved modifications better results have been reached in terms of air flow inside the booth. Next through the air flow simulation of outside booth the contaminated outdoor air has been easuily infiltrating into the booth through the window because of its rectangle shape. Stream like shape of booth has been proposed through the computer simulation as an alternative shape of tollgate booth for a new design.