• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.2
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• pp.271-276
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• 1989

Flame spreading over a hydrocarbon fuel surface has been investigated for liquid fuels such as kerosene and diesel, using thermocouple. Without forced convection, it was clearly found that the flame spreading was mainly controlled by the liquid fuel surface flow. Furthermore, the radiative heat transfer was dominant over a conductive heat transfer in kerosene. But in diesel the latter was found to be more influential than the former, when the direction of windflow was the same as that of flame spreading. The oscillation period and amplitude of the flame spreading velocity increase if the windflow is blowing in the direction of the flame spreading velocity, and decrease if the direction of windflow is blowing against the flame spreading direction.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.253-259
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• 1996

The purpose of this study is to investigate the fundamental properties of polyurethan concrete. Polyurethane must be expanded by means of a blowing agent during polymerization. Chemical blowing is caused by the reaction water with isocyanate. Binder system for polyurethane concrete is based on polyol and isocyanate with catalyst, surfactant, and methyl chloride. Polyurethane concretes are prepared with various grading of aggregate, and tested for compressive, flexural strengths, flow test, foaming multiple proportion, working life, condition of surface, distirbution of aggregate. From the test results, the foaming of polyurethane concretes are affceted by amount and grading of aggregate. Workability increases with raising amount of methy chloride and working life reduced according to amount of catalyst. The mix proportion of B with methyl chloride of 1% and catalyst of 0.1g for polyurethane concrete is recommended in consideration of strengths, condition of surface and balance between cost and performance.

• Journal of Mechanical Science and Technology
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• v.15 no.11
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• pp.1580-1587
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• 2001

In Part I, we extended the capability of the Goore Scheme for application to multi-dimensional problems and improved convergence performance. In this paper, we apply the improved Goore Scheme to th e control of turbulence for drag reduction. Direct numerical simulations combined with the control scheme are carried out to simulate a controlled turbulent channel flow at low Reynolds number. The wall blowing and suction is applied through the Goore algorithm using the total drag as feedback. An optimum distribution of the wall blowing and suction in terms of the wall-shear stresses in the spanwise and streamwise directions is sought. The best case reduces drag by more than 20 %.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.2
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• pp.57-63
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• 2010

Air curtains are widely used for gates of shopping mall, warehouse, cold stores and refrigerated display cabinets. The purpose of the air curtain is to reduce the infiltration of outdoor air and heat loss from the air conditioning space to ambient air. The discharge angle of air curtain is very important as the sealing efficiency is affected by it. This paper presents a performance of single jet air curtain in heating space when the discharge angle of nozzle changes. A numerical simulation is used to study the influence of various parameters on the efficiency of the downward-blowing air curtain device which is installed inside of the wall above the door. The performance of the air curtain is evaluated by sealing efficiency which provides the assessment of the energy savings. A condition of discharge angle that has the highest sealing efficiency is proposed.

• Journal of Environmental Health Sciences
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• v.3 no.1
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• pp.53-56
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• 1976

The air oxidations of asphalt at temperatures ranging from 190$\circ$C to 270$\circ$C were studied for changes in physical properties, proportions and chemical characteristics of asphalt compositions, weak acid and very weak acid contents. The following results were obtained: 1) Oils and resins of asphalt components are oxidized to asphaltenes by blowing(Air oxidation) 2) At 270$\circ$C, asphaltenes begin to undergo a change into benzene insoluble after approximately 12 hours of air oxidation. 3) Weak acid increases at the oxidation temperature below 200$\circ$C. While very weak acid, presumably phenols, generally increases without regard to the blowing(Air oxidation) temperature.

• Journal of the Korean Society of Safety
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• v.10 no.2
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• pp.92-96
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• 1995

The flash point is generally used as a hazardous index of fire or explosion of a flammable liquid. In this study, the lower flash points and the upper flash points according to the composition of Toluene-o-Xylene and Toluene-Methyl Ethyl Ketone mixtures are determined by air-blowing method. As results, relations between the flash points and the compositions of mixtures ; (1) for Toluene-o-Xylene mixtures $T_{fL}$=25.23 $\alpha$ ＋5.34 $T_{fu}$=27.36 $\alpha$ ＋40.50 (2) for Toluene-Methyl Ethyl Keton mixtures $T_{fL}$=10.00 $\beta$-5.00 $T_{fu}$=16.91 $\beta$＋20.45.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.524-527
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• 2000

In this paper, we have studied minimization of the burr which occurred after $\mu$-BGA(ball grid array) singulation process, singulation of the multilayer with a pulsed Nd:YAG(266, 532 nm) laser is used to cut the metal layer which doesn't well absorb laser beam. Especially, the photoresist and $N_2$blowing is effective to minimize of the surface demage and burr. In this experiment, the $N_2$ blowing reduces a laser energy loss by debris and suppress a surface oxidation. The SEM(scanning electron microscopes) and non-contact 3D inspector are used to measure cutting line-width and surface demage. The $\mu$-BGA singulation threshold energy is 75.0 J/cm$^2$at 30 ${\mu}{\textrm}{m}$/s scan speed.

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.61.4-61.4
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• 2008

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.107.2-107.2
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• 2007

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.35-35
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• 2003