• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.395-398
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• 2010

감압비등에 의한 미립화는 더 미세한 직경의 액적을 얻을 수 있고, 분무각이 증가하며, 더 좋은 혼합특성을 갖는 다는 점에서 단순 압력식 미립화와 차이가 난다. 감압비등이란 과열된 액체를 포화 압력 이하의 대기 중으로 분사하여 급격한 비등에 의해 이루어지는 미립화이다. 본 연구는 금속 연료를 이용한 추진기관의 산화제인 물 공급기술에 감압비등과정을 이용한 와류분무를 적용시키기 위해 수행됐다. 분열길이와 같은 거시적 특성은 Charge-Couple Device(CCD) 카메라를 이용해 측정하였고, Sauter Mean Diameter(SMD)와 SMD분포와 같은 미시적 특성은 Global Sizing Velocimetry(GSV) 시스템을 이용해 측정했다. 실험은 압력과 온도, 대류 속도를 변화시키며 진행했다.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2004.10a
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• pp.235-240
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• 2004

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2002.05a
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• pp.163-167
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• 2002

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2002.11a
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• pp.158-163
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• 2002

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2003.10a
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• pp.249-253
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• 2003

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2003.04a
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• pp.112-117
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• 2003

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.3
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• pp.367-373
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• 2003

The present study investigates the fire suppression characteristics using a water mist fire suppression system. The fire extinguishing times are measured for various fire sources, fuel types, and different total flooding rates of water mist. Pool fire with hydrocabon fuel is successfully extinguished within a minute under the operating conditions of the water mist system. Two different regimes of the smoke layer cooling are observed, such as rapid and slow cooling processes. The regimes are divided by threshold time which is calculated with auto-correlation function. The threshold time for the initial cooling decreases with increasing water flow-rates and fire sources. These initial cooling effects play an important role in preventing the occurance of flashover fire by the initial fire suppression.

• Fire Science and Engineering
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• v.22 no.3
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• pp.221-227
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• 2008

In this study, the fire suppression characteristics of a water mist with natural wind in a road tunnel were calculated using the FDS(Fire Dynamic Simulation) code. In addition, the cooling and the chemical kinetic effects of water vapor on fire extinction ere investigated in a counterflow non-premixed flame using a detailed chemistry. As a result, the behavior of fire plume and the spray characteristics of water mist are modified remarkably with the increasing of wind velocity. In the case which is not the external natural wind, small droplets are more efficient in fire suppression than large droplets. However, the large droplets show better results on the fire suppression than the small droplets with the increasing of wind velocity. It can be estimated that the natural wind disturb the penetration of water droplets into the flame region and decrease the effect of oxygen dilution. Finally, it can be identified that the fire into the natural wind can be suppressed with smaller amount of $H_2O$ by flame stretching effect in the flame region than one in an enclosure, and the chemical kinetic effects of $H_2O$ on fire extinction are not affected significantly the velocity of natural wind.

• Food Science and Preservation
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• v.9 no.2
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• pp.212-220
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• 2002

Spray drying was used a means for microencapsulation of Aster scaber and Aster glehni. The optimum conditions of spray drying were found to be 210$^{\circ}C$ for the inlet temperature and 5 $m\ell$/min for the feeding rate. The color difference decreased by 12∼25 % far the herb extracts depending on storage temperatures. With an increase in storage temperature, color of the control changed considerably compared to microencapsulated powders. This is due to the fact that wall materials minimized effect of oxygen on the herb extracts. Microencapsulated powders in the amounts of 50 ppm and 250 ppm added to hydrogenated soybean oils led to lower acid values and conjugated diene values during 6 day storage. Compared to the control, the herb extracts displayed 16∼48% increase in antioxidation effect, while the microencapsulated powders exhibited 46∼88% increase. Extracts also showed lower conjugated dienoic acid contents than those of the control. Although antioxidation effect of the microencapsulated powders did not prevail on the significant level in the early stage of storage of oils tested, it became predominant after one week of storage as wall materials were gradually degraded under the high temperature thereby releasing core material from the microcapsule.

• Journal of Bio-Environment Control
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• v.20 no.4
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• pp.394-398
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• 2011

The effect of two-fluid fogging system on the control of Bemisia tabaci in tomato cultivation was evaluated in a greenhouse. The number of Bemisia tabaci was decreased by 87% from the fog treatment for 7 days. During the fog treatment, the mean daily temperature was decreased by $2^{\circ}C$ and the mean daily relative humidity was increased by 3~4% as compared to the non-treatment. The reduction of Bemisia tabaci in the treatment might not be resulted from the differences in temperature and humidity in the greenhouse. The sound coming from the two-fluid fogging system did not affect when it was operated without water inside. Therefore it was concluded that water droplets coming out the nozzle reduced the growth and the movement of whiteflies because the suspension of tiny water droplets were attached on the skin of whiteflies.