• Fire Science and Engineering
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• v.16 no.1
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• pp.1-7
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• 2002

Halogen-based fire suppressing agents have environmental problems because they cause the stratospheric ozone depletion and globe warming. Hence, fire suppression system using fine water mist became the center of interest as a substitution of halon. As a study about this, it is in progress to make the optimum droplet size by using water mist nozzles and to improve the extinguishing performance of water mist by using additives. Before this study, the extinguishing time of ethanol and n-heptane pool fire was measured with changing of water mist droplet size, flow density, discharge pressure, and fire size. In this study, on adding the additives to improve physical and chemical extinguishing performance of water mist, the extinguishing performance would evaluate and the optimum condition would find out. As a result, in case of ethanol pan 1 pool fire, the extinguishing time of the water mist by adding of 2.5 wt% NaCl and 0.3% AFFF got shorter 27% and 60% than the pure water mist. Adding of AFFF was to decrease the flame temperature by forming thin film on the fuel surface and to decrease the evaporation of n-heptane fuel. In case of NaCl, alkali salt crystals showed on the flame surface.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.175-178
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• 2008

Spray characteristics for the simplex atomizer are investigated. The atomizer was tested with kerosene which is generally used as a fuel for gas turbine engines. But it is very difficult and dangerous to measure spray performance. So water is used as a working fluid for measuring the droplet information. In this study, spray visualization was performed by using ND-Yag Laser and droplet size was measured by using PDPA system by using two different working fluid such as water and test fluid # 2 which has similar characteristics of the kerosene. The test results show that SMD of water bigger than test fluid # 2 about 5$\sim$15 mm because surface tension of water is higher by a factor of 3. But the spray angles and the spray shapes have similarity

• Food Science and Preservation
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• v.24 no.2
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• pp.246-253
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• 2017

This study was conducted prepare spray-dried powder using pumpkin sweet potato hydrolysates and examine the physicochemical properties of the powder. The insoluble dietary fiber and soluble dietary fiber of the pumpkin sweet potato treated by enzyme were 4.17% and 2.07%, respectively. The spray-dried pumpkin sweet potato hydrolysates was manufactured via spray-drying with different forming agents: i.e., pectin 0.1%, 0.5%, 1%, and 2.0%. The moisture contents and total starches of the spray-dried powders were approximately 1.68-2.46 and 45.32-46.51%, respectively. The color of the L and a value decreased, and that of the b and ${\Delta}E$ value increased. The particle size and outer topology of the spray-dried powders were $37.17-42.32{\mu}m$, and its shape was generally globular. The water absorption index of the spray-dried powder (1.74-1.91) was lower than that of the freeze-dried powder (2.15). The water solubility index of the spray-dried powder, 80.75-87.61%, was higher than that of the freeze-dried powder (70.47%). The adhesion values of spray-dried powder to epithelial HT-29 cells were 2.66-6.18% of the initial cell counts, whereas freeze-dried powder showed lower adhesive ability (1.79%). The in vitro human digestibility in the spray-dried powder was 70.09% which is very effective in digestion.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.53-57
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• 2007

고속회전의 원심력으로 연료를 공급하고 액체연료의 미립화를 초래하는 회전연료분무장치에 대한 분무특성 시험연구를 수행하였다. 특정한 공간상에 존재하는 액적의 특성을 이해하고자 고속회전 연료분사시스템을 설계 제작하였다. 시험장치는 고속으로 회전하는 Spindle, 회전연료노즐, 가압식 물탱크, 아크릴 케이스로 구성하였다. 액적의 크기와 속도를 측정하기 위해 PDPA(Phase Doppler Particle Analyzer)시스템을 사용하였고, ND-Yag Laser를 사용하여 분무를 가시화 하였다. 시험결과 고속회전 연료분사시스템의 분무특성을 확인할 수 있었고, 회전속도는 액적 크기, 속도, 분무각 및 분무패턴 등의 분무특성에 주요한 영향을 미치는 것으로 확인되었다.

• Journal of ILASS-Korea
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• v.8 no.1
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• pp.29-36
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• 2003

Spray characteristics on diesel- water emulsion are analyzed in high pressure injection for several variables such as water content, injection pressure. Spray Patterns were visualized under various water content and injection pressures. Spray tip penetration was increased and spray angle decreased in accordance with increasing of water content. But these characteristics were enhanced with increase of injection pressure to high pressure.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.1
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• pp.61-67
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• 2015

The cooling of hot exhaust gas is an important issue for the construction of combustor test facility. Water spray is an effective method for exhaust gas cooling due to its large latent heat in process of evaporation. In this study, 1-D analysis has been performed based on continuity, energy conservation, and saturated vapor property to understand water spray cooling of combustion gas. In the exhaust duct of combustor test facility, the injected water decreases combustion gas temperature, and evaporates in the combustion gas. However, some of the injected water is collected in the sump due to condensation. The evaporation of water helps combustion gas cooling, but causes pressure increase inside the exhaust duct due to increase of vapor pressure. These phenomena has been analyzed by 1-D modeling in this study. From 1-D analysis, the adequate mass flow rate of water spray to cool combustion gas and to avoid excessive pressure rise inside the exhaust duct has been decided.

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.11a
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• pp.18-18
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• 1999

• Fire Science and Engineering
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• v.34 no.4
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• pp.7-12
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• 2020

A numerical study was conducted to investigate the effects of the spray characteristics of water mist on the attenuation of thermal radiation. The attenuation process of the thermal radiation, generated from a hot surface panel, passing through the water mist was calculated via Fire Dynamics Simulator (FDS), and the effects of the flow rate, droplet mean diameter, and spray injecting angle of the water mist were analyzed. The results indicated that the increase in flowrate and decrease in droplet size led to an increase in the attenuation of thermal radiation. As the thermal radiation passed through the spray droplets, the effect of the spatial distribution of spray droplets was verified by calculating the thermal radiation attenuation at different spray injecting angles. The results indicated that the radiation attenuation increases as the spray angle increases. This implies that a wider distribution of spray droplets, irrespective of the droplet size and flowrate, increases the attenuation effect on thermal radiation.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2013.11a
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• pp.229-229
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• 2013

본 연구에서는 미세 물분무 노즐의 소화성능을 분석하기 위해 유량계수, 방사거리, 방사각도, 그리고 작동압력에 따라 분사되는 물입자 크기를 측정하였다. 이를 위해서 이중 구조의 미세 물분무 노즐 LPN-61과 LPN-63을 제작하였으며, 미분무 소화설비를 구성하여 이중구조 노즐의 형상에 따라서 유동특성을 정량화하였다. 그 결과 LPN-61은 유량계수 5.116, 방사각 $120^{\circ}{\sim}125^{\circ}$로 작동압력이 $4kgf/cm^2$에서 $10kgf/cm^2$까지 증가함에 따라서 SMD는 $127{\mu}m$정도에서 $88{\mu}m$까지 입자 크기가 감소하였으며, LPN-63은 유량계수 5.121, 방사각도 $120^{\circ}{\sim}125^{\circ}$로 동일한 작동압력 범위에서 SMD는 $108{\mu}m$에서 $80{\mu}m$까지 감소하는 것을 확인하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.6
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• pp.41-47
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• 2009

This paper presents the spray characteristics of the simplex fuel nozzle with different working fluids for the gas turbine engine. Spray characteristics can be changed with viscosity, surface tension and density. In this research, water and test fluid type 2 which has similar characteristics of the kerosene are used as a working fluid. Spray visualization was performed by using ND-Yag laser and droplet size was measured by using PDPA(Phase doppler particle analyzer) system. The test results show that spray shapes and SMD distributions of two working fluids are similar at main spray region.