• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회논문집(II)
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• pp.671-676
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• 1998

This study deals with the effect on penetration properties of siliceous ion througth the mortar applicated by the waterproofing coating materials of siliceous seler liquid type. The tests of properties for reinforcing effect in mortar substrate surface layer are five kinds of water permeability, absorption, compressive strength, surface layer strength, pH content and chemical attack effect. Water permeability of mortar coated siliceous sealer in very than that of plane mortar. compressive strength of mortar coated siliceous sealer in larger than that of plane mortar about 10%.

• 대한기계학회논문집B
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• 제22권8호
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• pp.1132-1140
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• 1998

The disintegration process of initial spray from high-pressure swirl injector was investigated at different injection pressures. The transient breakup phenomena that were difficult to observe at high injection pressure were easily observed at the low injection pressure of 0.4MPa. The effect of fuel remained inside a nozzle hole volume on the penetration of initial spray was also investigated. The disintegration process of initial spray could be classified four regions: the formation of mushroom shape, the first collision, the second collision, and the development of spray, The liquid film of cup shape was particularly found in the second collision region, and the growth ratio of its length and width at low and high injection pressures were compared.

• 대한기계학회논문집B
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• 제29권10호
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• pp.1111-1118
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• 2005

In this study, a unified numerical investigation has been performed on the evolution of weld pool and key-hole geometry during low-power and high-power density laser welding. Unsteady phase-change heat transfer and fluid flow with the surface tension are examined. The one-dimensional vaporization model is introduced to model the overheated surface temperature and recoil pressure during high-power density laser welding. It is shown that Marangoni convection in the weld pool is dominant at low-power density laser welding, and the keyhole with thin liquid layer and the hump are visible at high-power density laser welding. It is also shown that the transition from conduction welding to penetration welding fur iron plate exists when the laser power density is about $10^6W/Cm^2$.

• 한국가구학회지
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• 제18권2호
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• pp.161-165
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• 2007

An experiment was conducted to observe the safranine flow depth in longitudinal direction of Populus tomentiglandulosa. Longitudinal flow of safranine was considered from bottom to top end of the tree. Vessel and wood fiber were considered for the measurement of safranine flow depth. It was found that sapwood conducted safranine 12.25% higher in longitudinal direction compared with heartwood. Vessel was found the main avenue for safranine flow. Vessel conducted safranine 41.94% higher than that of wood fiber. Safranine penetrated through vessel and fiber forming a curved meniscus.

• 한국분무공학회지
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• 제2권1호
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• pp.36-45
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• 1997

A spray-wall impingement model for fuel sprays is proposed and implemented as a module into the KIVA-POSTECH code. The model is based on the single droplet experiments. The droplet behaviors after impingement are determined from experimental correlations. Different behaviors of impinged droplets depend on the wall temperature and the critical temperature of the fuel. Fuel film formation is taken into account so that the model can be applicable to any wall temperature and injection conditions. Computational results on a normal and on inclined wall are in good agreement for the spray shape and penetration. More validation against experiments and development of the heat transfer model are needed for further improvement.

• 한국분무공학회지
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• 제5권4호
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• pp.33-39
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• 2000

The behavior of the 2-stage spray was studied by using the schlieren method with the high pressure common-rail injection system. The spray injected 2 times with the interval of $0.3ms{\sim}1.5ms$ between the 1st and the 2nd spray in a modeled combustion chamber of constant volume bomb. In this case, the quantity of injected fuel of 1st and 2nd also changed. The schlieren photograph shows that the 2nd spray goes further away than the 1st spray when the quantity of the 1st spray is less than that of the 2nd spray. The dispersion of the vapour to the combustion chamber is not affect in a 10% of 1st spray quantity. When the 1st spray quantity is more than the 2nd spray, the vapour scattering of spray is good.

• 한국분무공학회지
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• 제12권1호
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• pp.30-37
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• 2007

Dimethyl ether (DME) as an alternative fuel for compression ignition engine was investigated by measuring spray development processes, injection rate profiles, engine performance, and exhaust emission characteristics. The results of DME fueled engine were compared with those obtained by fueled with diesel. The experimental results showed that DME has approximately 0.03ms shorter injection delay and higher maximum injection rate than those of diesel fuel at a constant injection pressure of 50MPa. The spray visualization indicates that DME has shorter spray tip penetration due to its low density and faster evaporation. The combustion characteristics of DME operated engine provided faster ignition delay and three times shorter combustion duration. It is believed that the better evaporation and atomization characteristic of DME contributes the faster combustion. At all operating condition, soot emission was not detected due to the clean combustion of DME.

• 한국분무공학회지
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• 제15권2호
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• pp.61-66
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• 2010

Fuel spray characteristics of the gasoline engine injector has been studied experimentally. To provide fundamental performance data of 4-hole and 12-hole injectors, spray fuel-mass distribution, wall wetting fuel amount and visualization of injectors have been tested and measured with various fuel supply pressure conditions. Spray visualization has been performed to analyze spray formation, spray angle, stream width and penetration length. Test result shows that wall wetting is greatly influenced by the induction air amount and spray atomization. Spray visualization shows that the 12-hole injector has robust performance characteristics with various fuel supply pressure conditions compared with the 4-hole injector. 4-hole injector generates relatively less wall-wetting fuel amount than 12-hole injector does.

• 한국분무공학회지
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• 제15권2호
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• pp.67-73
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• 2010

The capability of pilot injection with small fuel quantity at all engine operating conditions is one of the main feature of the common rail direct injection system. The purpose of the pilot injection is to lower the engine noise and to reduce the NOx emissions. This study describes the pilot spray structure characteristics of the common-rail diesel injectors with different electric driving characteristics, including solenoid-driven and piezo-driven type. Namely three common-rail injectors with different electric current wave were investigated in this study. The pilot spray characteristics such as spray speed, spray tip penetration, and spray angle were obtained by spray images, which is measured by the back diffusion light illumination method with optical system for high-speed temporal photography. As this research results, it was found that pilot injection of common-rail system was effected by rate of injection with different electrical characteristic for injector driving.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 추계 학술논문 발표대회
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• pp.173-178
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• 2008

This is green roof bottom system which composed by aluminum valve and glass fiber together as major reinforcement, so the cooper sheet can have root proof, and using recycled tire gel-type membrane waterproofing system which dost not contains VOCs. The copper sheet reduce the plants' root growing, so it helpes to maintain the waterproofing layer and stability of root proofing. Gel type membrane waterproofing system can do waterproofing, stress dispersion, and reducing leakage expansion. So those two materials can help each other to make green roof bottom layer would have the stability and durability.