• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.11a
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• pp.8-14
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• 2001

The purpose of this study is to elucidate heat characteristics according to inclination angle of the hot flat plate at the spray cooling. As results of this experiment, the heat flux, the heat transfer coefficient and the cooling speed are increased as the liquid volume flux and subcooled temperature go up. And as the inclination angle of the heat transfer surface is increased, the cooling speed on the inclined flat plate becomes faster. It means that the cooling ability is increased because droplets were excluded by gravity.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.249-249
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• 2004

다양한 기계적인 제거 가공 공정에 있어서 발생되는 열의 냉각과 치핑 과정시의 원활한 윤활 및 칩의 효율적인 배출 작용 등을 위하여 필수적으로 적용되는 절삭유와 관련한 분야에 있어서 최근에 환경성과 경제성을 고려한 청정 생산 기술의 도입이 전 세계적으로 활성화되면서 사용량을 억제하거나 대체화하는 방식과 폐절삭유의 발생을 저감화하기 위한 수명 향상 방식 등을 위한 관련 연구들이 경쟁적으로 진행되고 있다. 그러나 현재까지 불가피하게 수용성 절삭유를 일반적으로 사용하는 국내 중소기업 형태의 영세한 생산 제조 작업 현장에 있어서는 비산, 분무되는 절삭유에 의하여 작업 환경이악화될 뿐만 아니라 점진적으로 부패되어 악취가 발생됨으로써 작업자가 기피하거나 산업 재해의 원인으로서도 작용되므로 우선적으로 절삭유의 사용량을 억제하기 위하여 최소한의 적정량만을 적용할 수 있는 기법을 채택하거나 절삭유의 수명을 극대화하기 위하여 적정한 상태를 유지할 수 있는 방식이 요구된다.(중략)

• Proceedings of the SAREK Conference
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• 2004.06a
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• pp.174-174
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• 2004

• The Korean Journal of Food And Nutrition
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• v.10 no.2
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• pp.234-240
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• 1997

Agar has widely been used as medical aids and food ingredients due to its pecular physicochemical and rheological properties. In this paper, the effects of spray drying and extrusion drying on functional properties of agar were investigated to clarify the sol-gel transition mechanism at low temperature and microstructure of agar gel by measuring phase transition by differential scanning calorimetery, structural differences by light microscope and scanning electron microscope observation. The lowest endothermic onset(To), peak(Tp), conclusion(Tc) temperature and enthalpy($\Delta$H) using differential scanning calorimetery were showed in extrusion-dried agar wic were checked in 41.30, 61.72, 80.50 and 0.73cal/g. In cases of unmodified and spray-dried, the values were 81.20, 95.51, 112.14 and 3.22cal/g, and 60.11, 76.45, 89.54 and 1.53cal/g, respectively. When all samples were reheated using differential scanning calorimetery after gelling fully, no significant differences of endothermic To, Tp, Tc and $\Delta$H appeared. The surface structure of unmodified agar powder observed by light microscope and scanning electron microscope appeared a continuous surface without any indication of small pores, gaps or point of discontinuity. In cases of spray-dried agar, the unstable structures with pores was resulted. The microstructures of extrusion-dried agar, however, was solid with large gaps and areas of discontinuity in the surface. From the results above, it was suggested that significant differences in phase transition and surface microstructures were clearly related to the physicochemical changes and rheological properties, solubility and gelling ability of the types of agar gel.

• Fire Science and Engineering
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• v.22 no.3
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• pp.216-220
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• 2008

Water mist fire suppression system utilizes the fire suppression features such as cooling of fire source, dilution of ambient oxygen, and shielding of radiation heat with the evaporation of microscopic water droplets. The momentum of water mist is relatively lower than that of larger water droplet and the infiltration of water mist to the fire source is not effective. Contribution of evaporated water vapor is liable to decline to limited portion of fire source due to its light weight and sparse density. On the other hand, the cycling water mist pattern is expected to improve the penetration force of water mist as well as the air expelling capability with the stratified spray characteristics. At this paper, we present the analyzed fire suppression capability of intermittent water spray pattern by use of FDS which is computational fire dynamics fire model. We expect this analysis can support the basic concept to the development of the prototype of water mist nozzle.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.3
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• pp.247-255
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• 2004

The cooling characteristic of water-air mixed spray for high water mass flux is not well defined, compared to that of highly pressurized spray. A series of research program was planned to develop the boiling correlation for whole temperature range in case of water-air mixed spray with high water mass flux. The cooling experiments of hot steel surface with initial temperature of 820$^{\circ}C$ were conducted in unsteady state with relatively high water mass flux. A computer program was developed to calculate the heat flux inversely from measured data by three inserted thermocouples. Finally the effects of water and air mass flux on the averaged film boiling heat flux and wetting temperature were studied. In this 1st report, it is found that the boiling curve was similar to that of highly pressurized spray and the decreased slope of heat flux in film boiling region with respect to surface temperature became steep by increasing air mass flux. Also it is shown that, by increasing air mass flux, the averaged heat flux in film boiling region was increased, and then saturated and the wetting temperature was increased, and then decreased. Finally when the heat flux in film boiling region is compared with that of highly pressurized spray, it is known that the cooling is improved by introducing air up to 60%.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.1
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• pp.36-44
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• 2012

Multi-injector rocket engine using high-concentrated hydrogen peroxide and kerosene was designed and manufactured. Design requirements of a rocket engine were determined and main geometrical parameters of rocket engine were determined on the basis of fundament. Six coaxial swirl injectors were mounted on the multi-injector engine. Flow analysis in the hydrogen peroxide manifold was performed to minimize stagnation and recirculation zones. Finally, the optimized hydrogen peroxide manifold was manufactured and cold flow test was carried out to confirm mass flow rate per uni-element, spray pattern and atomization characteristics. The results of cold flow test showed that the mixing head design process was successful and enough to use as a essential database for the development of a full-scale engine.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.1
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• pp.12-17
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• 2014

The cooling of precooked skipjack Katsuwonus pelamis is a critical thermal process in tuna canning because it affects the quality and yield of the canned tuna, as well as productivity. The combined method of vacuum cooling followed by water spraying (VC-WS) was investigated to increase cooling rates, and prevent loss of yield of the precooked tuna during vacuum cooling. For VC-WS, the precooked skipjack was cooled to $30^{\circ}C$ by vacuum at 31 mmHg and then wetted by spraying water for 2 min. The effects of VC-WS on cooling times, cooling loss, color, texture and lipid oxidation of the precooked tuna were compared with conventional spray cooling (SC).The cooling times for precooked skipjack from $75^{\circ}C-30^{\circ}C$ were 11 min for VC-WS and 145 min for SC. The cooling losses were 1.7 % for VC-WS and 1.6 % for SC. Peroxide and thiobarbituric acid (TBA) values of VC-WS were lower than those of SC. The loin of the VC-WS-treated skipjack was brighter and harder than the SC loin, as indicated by higher lightness and hardness values. Based on these results, we believe that the VC-WS process could compensate for the cooling loss of vacuum cooling and minimize changes in quality that occur during cooling of precooked skipjack tuna.

• Journal of Bio-Environment Control
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• v.9 no.1
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• pp.27-39
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• 2000

In this study, we quantitatively compare the cooling effects of single span plastic greenhouses by opening or shutting of toot and side vents, and operation of fan or sprinkler. With those variables, we simultaneously made experiments at 4 greenhouses under equivalent conditions. By the experiments, the shutting of roof and side vents caused the high temperature difference of indoor and outdoor which the crops cannot be cultivated. However, the opening of the windows effectively reduced the indoor temperature and showed uniform temperature distribution in the greenhouses. The sprinkler abruptly reduced the indoor temperature, and showed excellent cooling effects. Finally, this paper provides the fundamental data for environmental control in greenhouses.

• Journal of Bio-Environment Control
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• v.8 no.4
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• pp.281-287
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• 1999

In order to take a good look at effectiveness of cooling of Fog system and Pad-Fan system, we chose 49 farm households which were installed evaporative cooling system and 2 farm households which were installed Pad-Fan system and Fog system for a test. We execute the test on 29 households out of 49.6 households, which were installed Pad-Fan system, were able to use; however, 6 household out of 9 which were installed Fog system couldn't use it. The main reason was the clogged on nozzle. The cooling efficiency on Pad-Fan system was 77.4%, but it was very poor on Fog system. Since there are many problems on Fog system, we need more research on size of fog, the location of nozzle, control of Fog systems.