• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2001년도 추계학술대회 논문집
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• pp.413-414
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• 2001

실내공간에 존재하는 먼지입자를 제거하는데 적용되는 대표적인 방법들로는 섬유상 필터를 이용한 먼지입자 여과 기술과 전기집진기를 이용한 여과 기술이 있다. 섬유상 필터를 이용한 여과 기술은 입자의 관성충돌(inertial impaction), 차단(interception) 및 확산(diffusion) 메카니즘을 이용한 기술로써, 입자포집 효율이 아주 우수한 반면 압력손실이 큰 단점이 있다. 이러한 단점을 개선하기 위하여 개발된 필터로써 정전부착(electrostatic deposition) 메카니즘을 이용한 정전여과필터(electret filter)라고 것이 있는데, 이것은 섬유 자체에 정전 하전을 주입시킨 특수한 필터이다. (중략)

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.363-365
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• 2007

Titanium and its alloys have excellent corrosion resistance, high strength to weight ratios and high temperature creep properties, which make them using many various fields of application. Responding to these needs, welding processes for titanium are also being used including TIG, MIG, resistance welding, plasma arc welding, diffusion welding, electron beam welding and laser welding. In this study, It is possible to get sound beads without humping bead and spatter with the decrease of peak power according to increase of pulse width and change of welding speed for heat input control at pulsed Nd:YAG laser welding of titanium plates for Lap welding.

• 수산해양기술연구
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• 제30권2호
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• pp.109-115
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• 1994

This paper presents a new concept to reduce turbulent frictional drag by injecting micro-bubble into near the buffer layer of turbulent boundary layer on flat plate. The concentrations of micro bubble distribution in the boundary was calculater by eddy viscosity equations in the governing equations. When near region of the buffer layer of turbulent boundary layer is filled with micro-bulle of air and viscous of the region is kept low, the velocity profile in the near region should be changed substantially. Then the Reynolds stress in the region becomes less, which guide to lower velocity gradient there. It results in reduction of velocity gradient at the viscous sublayer, which gives the reduction of shear stress at the wall.

• 한국미생물·생명공학회지
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• 제33권3호
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• pp.236-239
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• 2005

Ethyl acetate extracts of traditional medicinal herbs were screened for their antifungal activity against Malassezia furfur through the liquid growth inhibition method with 96 well plate and the paper disk agar diffusion assay. Among the 91 kinds of herbal solvent extracts, borneolum (borneo-camphor, No. 56) was finally selected as the best antifungal effective medicinal herb. The MIC value of No. 56 against M. furfur was 0.3 mg/ml ($8.2{\times}10^6$ CFU/ml) and it was three times more efficient than midazole which is the known antifungal agent in clinical medicines.

• 설비공학논문집
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• 제13권5호
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• pp.422-430
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• 2001

In the present study, an evaporative generation process of ammonia-water solution film on the vertical plate was analysed. For the utilization of waste heat, hot water of low temperature was used as the heat source. The continuity, momentum, energy and diffusion equations for the solution film and vapor mixture were formulated in integral forms and solved numerically. Counter-current solution-vapor flow resulted in the refrigerant vapor of the higher ammonia concentration than that of co-current flow. Eve the rectification of refrigerant vapor was observed near the inlet of solution film in counter-current flow. For the optimum operation of generator using hot water, numerical experiments, based on the heat exchange and generation efficiencies. revealed the inter-relationships among the Reynolds number of the solution film and hot water, and the length of generator. Enhancement of heat and mass transport in the solution film was found to be very effective for the improvement of generation performance, especially at high solution flow rate.

• 설비공학논문집
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• 제11권3호
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• pp.414-421
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• 1999

Falling film rectification involves simultaneous heat and mass transfer between vapor and liquid interface. In the present work, the adiabatic rectification process of ammonia-water vapor on the vertical plate was investigated. The continuity, momentum, energy and diffusion equations for the solution film and vapor mixture were formulated in integral forms and solved numerically. The model could predict the film thickness, the pressure gradient, and the mass transfer rate. The effects of Reynolds number and ammonia concentration of solution and vapor mixture, rectifier length, and the enhancement of mass transfer in each phases were investigated. The stripping of water in vapor mixture occurred new the entrance of ammonia solution, which imposed the proper size of an adiabatic rectifier. Rectifier efficiency increased as film Reynolds number increased and as vapor mixture Reynolds number decreased. The improvement of rectifier efficiency was significant with the enhancement of mass transfer in falling film.

• International Journal of Air-Conditioning and Refrigeration
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• 제8권2호
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• pp.69-79
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• 2000

Falling film rectification involves simultaneous heat and mass transfer between vapor and solution film. In the present work, the adiabatic rectification process of ammonia-water vapor by the falling solution film on the vertical plate was investigated. The continuity momentum, energy and diffusion equations for the solution film and the vapor mixture were formulated in integral forms and solved numerically, The model could predict the film thickness, the pressure gradient, and the mass transfer rate. The effects of Reynolds number and ammonia concentration of solution and vapor mixture, rectifier length, and the enhancement of mass transfer coefficient in each phases were investigated. The stripping of water in vapor mixture occurred near the entrance of ammonia solution, which imposed the proper size of an adiabatic rectifier. Rectifier efficiency increased as film Reynolds number increased and as vapor mixture Reynolds number decreased. The improvement of rectifier efficiency was significant with the enhancement of mass transfer coefficient in falling film.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.423-426
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• 2005

Steel reinforced concrete (SRC) columns, which are widely employed in high-rise buildings, exhibit particular time-dependent behavior due to creep and shrinkage of the concrete, and this behavior may cause problems related to serviceability and structural stability. SRC columns also exhibit a time-dependent, cross-sectional relative humidity distribution that differs from reinforced concrete (RC) columns, due to the presence of an inner steel plate, which interferes with the moisture diffusion of concrete. This differential moisture distribution of SRC columns may reduce the drying shrinkage and the drying creep as contrasted with RC columns. Therefore, we propose that the differential moisture distribution be taken into account to accurately predict SRC column shortening.

• 설비공학논문집
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• 제13권11호
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• pp.1134-1140
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• 2001

In the present study, heat transfer characteristics of oil flow over offset strip fins were predicted by the numerical methods. Oil flow in the plate-fin passage was idealized by 2 dimension. Power law scheme and SIMPLE algorithm were used for convective diffusion formulation and pressure term respectively. Governing equations were discretized by control volume formulation. The flow patterns and heat transfer were predicted in details. The convective heat transfer coefficients were affected by separation bubbles which appeared at the wake region of offset strip fins.

• 대한기계학회논문집
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• 제16권2호
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• pp.382-390
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• 1992

The problem of natural convection from a vertical fin is solved by coupling the thermal diffusion equation in the fin to the constitutive equations of the ambient medium involving the radiation of the medium. The analysis is accomplished by employing an integral method. The governing equations for the problem are solved by shooting method based on the Runge-Kutta Scheme at Pr= 0.7. For the range of values of the fin parameter and the radiation-conduction parameter in the analysis, the numerical results show that the radiation effects play an important role in the heat transfer and enhance the heat transfer.