• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.10
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• pp.817-824
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• 2015

Experiments were carried out to investigate the flow and mass transfer characteristics of an orifice nozzle. Measurements of primary and suction flow rates, dissolved oxygen concentration, and electric power were obtained. Vertically injected mixed-jet images were captured by a direct visualization technique with a high speed camera unit. The mass ratio, volumetric mass transfer coefficient, and mass transfer performance were calculated using the measured data. As the primary flow pressure increases, the mass ratio decreases slightly, while the volumetric mass transfer coefficient and electric power increase. As the primary flow pressure increases and the mass ratio decreases, the mass transfer rate increases because of the fine bubbles and wider distribution of the bubbles.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.10a
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• pp.39-42
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• 1998

1. 서론 : 막을 경계로 접촉한 두 상(phase)간의 물질전달에 의해 물질을 효과적으로 분리해내는 막접촉기(membrane contactor) 방식은 추출이나 흡수에 적용되고 있다. 이것은 고전적인 충전탑이 갖는 접촉면적의 한계, 불안정한 유체유동의 단점을 가급적 극복할 수 있다는 측면에 있다. 막접촉방식의 하나인 막 흡수법의 경우, 흡수제(absorbent)를 정지시킨 contained(혹은, supported) liquid membrane 방식에서 인공폐의 원리를 기초로 독립적으로 분리시킨 흡수와 탈착모듈간의 계속 순환시키는 circulatory membrane absorber방식이 제안되었다.(생략)

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.3
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• pp.362-370
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• 1998

Absorption systems require a heat source for working but they have a great merit in that relatively low-temperature and low-quality types of thermal energy such as solar heat and exhaust heat can be effectively utilized as heat source. However details research related to absorbers which have a great effect on performances has been rarely done and thus there has been a strong hope for positive developments to improve their efficiencies. This paper describes absorption experiments made with different inside tube diameters and shapes. The purpose of this study is to acquire basic knowledge about heat and mass transfer in a falling film type absorber with vertical inner tubes. Heat and mass transfer were measured for water vapor absorption into a water/LiBr solution flowing down an absorber of vertical inner tubes. As a result absorption acceleration tube compares bare tube and heat transfer improved by order of insert spring tube corrugated tube grooved tube. And the acceleration that is good provided in inserting spring tube for both sides of heat and mass transfer.

• Membrane Journal
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• v.4 no.4
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• pp.221-231
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• 1994

The GR51PP(MWCO 50,000) and GR40PP(MWCO 100,000) membranes manufactured by DDS were used in ultrafiltration of dextran(Mw. : 500,000) solution in flat plate ultrafiltration cell filled with various types of turbulence promoters. The flux improvement by using turbulence promoter was higher in laminar flow region than in turbulent flow region. The maximum improvements of permeate flux were foud as 112% and 50% I laminar flow region and turbulent flow region, respectively. Also, the solute rejection of the ultrafiltration membrane was improved by turbulence promoters and its effect was significant in the high transmembrane pressure and laminar flow region. The smaller the spacer mesh size was used, the higher the flux improved, but the pressure drop in ultrafiltration cell also increased. In laminar flow region, pressure drop by the spacer was negligible, but in turbulent flow region it changed significantly depending upon the mesh size of the spacer and therefore, its mesh size must be baken into account in the design of the process. The predicted results of the modified mass transfer correlation had better agreement with experimental results than those of unmodified one, The modified mass transfer correlations for laminar and turbulent flow region are shown as follow. $N_{sh}=0.151(N_{Re})^{0.199}(N_{Sc})^{0.22}(N_{Scm})^{0.197}\;(625 $N_{sh}=0.0165(N_{Re})^{0.428}(N_{Sc})^{0.33}(N_{Scm})^{0.223}\;(5015

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.2
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• pp.56-63
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• 1998

The present study investigated local heat transfer characteristics around a film cooling hole with variations of free stream turbulence intensity The film cooling jet is injected through a single hole inclined at $30^{\cire}$ to the surface and laterally at $45^{\cire}$ for the blowing rates of 0.5, 1.0 and 2.0. Turbulence generating grids are used at upstream of the film cooling hole to change the turbulence intensity of free stream. Free stream turbulence intensity without grids is 0.5%. Two different turbulence generating grid is installed at different at locations upstream of the film cooling hole so that turbulence intensity of free stream varies from 3% to 10%. The naphthalene sublimation technique has been employed to determine local heat/ mass transfer coefficients. With low free stream turbulence intensity, heat/mass transfer augmented area by coolant or free stream is distinguished evidently. However, when free stream turbulence intensity is high, heat transfer is enhanced in all region and heat transfer enhanced regions are not clearly divided due to vigorous mixing of coolant and free stream. The peak values of heat/mass coefficients are decreased and the distributions of heat/mass transfer coefficients are more uniform with high turbulence intensity. The effect of turbulence intensity on heat transfer characteristics is more evident as blowing rate is higher.

• The KSFM Journal of Fluid Machinery
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• v.11 no.6
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• pp.24-30
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• 2008

In order to enhance the heat/mass transfer, a turbulator has been installed at the exit of injection hole for the impingement/effusion cooling system. The local heat/mass transfer coefficients have been obtained by a naphthalene sublimation method. Experiments have been carried out at the fixed jet Reynolds number of 10,000. Two turbulators with different diameter have been used in the current study. The result presents that the turbulator leads to the increase in flow mixing and jet velocity, consequently enhancing the heat/mass transfer at a stagnation region. Further, the stagnation region is divided into four small areas with peak value. In the existence of initial crossflow, the stagnation regions move downstream and low heat/mass transfer regions are formed regardless of the installation of turbulator. However, the increased jet velocity by turbulator reduces the crossflow effect against the jet, resulting in decrease of low heat/mass transfer regions. Compared to the case without turbulator, the installation of turbulator yields $5{\sim}10%$ augmentation in averaged Sh value.

• Applied Chemistry for Engineering
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• v.3 no.1
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• pp.119-129
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• 1992

The rates of mass transfer with the alkaline hydrolysis of ethyl acetate and n-butyl acetate were measured by using a modified Lewis cell. The rates of mass transfer with chemical reaction were independent of the speed of agitation, and the reaction enhancement factors were independent of the ionic strength. The second order reaction rate constants of ethyl acetate and n-butyl acetate could be obtained from an approximate solution of a diffusion equation by film theory, and their values were $0.041m^3/kg\;mol{\cdot}s$ and $0.338m^3/kgmol{\cdot}s$, respectively.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.26 no.1
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• pp.1-16
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• 2000

Keratinocyte 는 피부 표피충의 대부분을 차지하고 있으며, 세포간 신호전달물질 cytokine을 생성분비함으로써 주위의 다른 피부세포의 활성 및 분화능력을 조절한다. 특히 melanocyte 한 세포는 keratinocyte 30 여 세포와 직접적으로 접촉하고 있으며 활발한 신호 전달을 통하여 피부생리의 동적평형 유지에 기여하고 있다. 본 연구에서는 실제 피부에서와 유사한 조건에서 keratinocyte 의 세포의 배출 신호물질인 cytokine 의 변화를 유도하는 물질이 melanocyte 의 피부색소형성과정에 기여하는 바를 평가하기위하여 keratinocyte-melanocyte 의 공동배양계 실험조건과 아울러, UVB 조사에 의해 keratinocyte 로부터 유리되는 물질이 melanocyte를 자극하여 melanin 생합성 유도를 촉진하는 기본 실험 System 을 확립하였고, 가능성있는 친연추출물 원료, 즉, 신이, 강황등의 melanin 생합성 억제능을 본 공동배양계에서 1차 평가한 후 소규모 임상실험에서 미백효능을 최종 평가하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.6
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• pp.1501-1509
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• 1995

It is known that the heat and mass transfer characteristics in the absorber are most sensitive of the temperature boost of all the heat exchangers and the development of a more efficient absorber should be highly important. This paper describes absorption experiments made with different inside tube diameters, tube length and tube shapes. The purpose of this study is to acquire basic knowledge about heat and mass transfer in a falling film type absorber with vertical inner tubes. Heat and mass transfer were measured for water vapor absorption into a Lithium Bromide-water solution flowing down an absorber of vertical inner tubes. As a result, insert spring tube compares bare tube and heat transfer improved by order of insert spring tube P2(pitch 20 mm) and P1(pitch 10 mm).

• Journal of computational fluids engineering
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• v.7 no.1
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• pp.36-43
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• 2002

A numerical investigation is made of unsteady double-diffusive convection of a Boussinesq fluid in a rectangular cavity subject to time-periodic thermal excitations. The fluid is initially stratified between the top endwall of low solute concentration and the bottom endwall of high solute concentration. A time-dependent heat flux varying in a square wave fashion, is applied on one sidewall to induce buoyant convection. The influences of the imposed periodicity on double-diffusive convection are examined. A special concern is on the occurrence of resonance that the fluctuations of flow and attendant heat and mass transfers are mostly amplified at certain eigenmodes of the fluid system. Numerical solutions illustrate that resonant convection results in a conspicuous enhancement of time-mean mass transfer rate.