• 대한기계학회논문집
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• 제19권9호
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• pp.2249-2260
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• 1995

An experiment of close contact melting of phase-change medium partially filled in an isothermally heated horizontal cylinder is performed which involves the volume expansion of liquid induced by the solid-liquid density difference. The solid-liquid interface motion and the free surface behavior of liquid were reported photographically. The experimental results show that the curvature of upper solid-liquid interface varied to flat as melting progresses. In addition to the varying interface shape, the melting rate increases with the lower initial height of solid and the free surface height of liquid increases linearly. The experimental results of molten mass fraction were expressed in a function of dimensionless time Fo.Ste$^{3}$4/ and agreed well with the analytical solutions.

• 통합자연과학논문집
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• 제6권1호
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• pp.12-15
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• 2013

To combine the micro rain radar and microwave radiometer cloud liquid water, we estimate the cloud physical thickness from the difference between the MTSAT-1R cloud top height and cloud base height of visual observation of Daegwallyeong weather station, and the cloud liquid water path of micro rain radar is obtained by multiplying the liquid water content of micro rain radar and the estimated cloud physical thickness. The trend of microwave radiometer liquid water path agrees with that of the micro rain radar during small precipitation. We study these characteristics of micro rain radar and microwave radiometer for small precipitation to obtain the combined cloud water content of micro rain radar and microwave radiometer, constantly operated regardless to the rainfall.

• 한국습지학회지
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• 제16권2호
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• pp.205-212
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• 2014

본 연구는 환경, 에너지, 재료 등 다양한 분야에 적용할 수 있는 초음파 기술을 수처리 공정에 적용하기 위한 기초 연구로 수행되었다. 초음파 기술과 같은 고도산화처리공법은 중금속, 내분비계장애물질, 의약물질 등의 미량오염물질 처리에 효과적이어서 하천, 호소, 습지의 수질 향상에 크게 기여할 수 있을 것으로 기대되고 있다. 초음파 기술은 파를 기반으로 하기 때문에 본 연구에서는 적용 주파수의 파장을 이용하여 $0{\sim}4{\lambda}$ 구간의 수위를 $1/4{\lambda}$ 간격으로 나누어 동일한 유입에너지 조건에서 발생하는 열에너지 및 초음파 캐비테이션의 화학적 효과를 정량화 하였다. 실험 결과 낮은 수위 (적은 부피)의 에너지 밀도가 높은 조건보다 높은 수위 (큰 부피)의 에너지 밀도가 낮은 조건에서 열에너지 및 화학적 효과가 극대화되는 것을 확인하였다. 이러한 현상을 반응기 내부의 캐비테이션 활성도 시각화를 통해 알아본 결과, 높은 수위 (큰 부피) 조건에서는 에너지 밀도가 낮음에도 불구하고 반응기 전체적으로 높은 활성도를 얻을 수 있기 때문인 것으로 확인되었다. 따라서 본 연구결과를 이용하여 초음파 기술을 수처리 분야에 적용할 경우 반응성 및 에너지 효율 측면에서 적용 가능성을 보다 높일 수 있을 것으로 예상된다.

• Earthquakes and Structures
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• 제8권3호
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• pp.779-799
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• 2015

The slosh height and the possibility of water spill from rectangular Spent Fuel Storage Bays (SFSB) and Tray Loading Bays (TLB) of Nuclear power plant (NPP) are studied during 0.2 g, Safe Shutdown Earthquake (SSE) level of earthquake. The slosh height obtained through Computational Fluid dynamics (CFD) is compared the values given by TID-7024 (Housner 1963) and American concrete institute (ACI) seismic codes. An equivalent amplitude method is used to compute the slosh height through CFD. Numerically computed slosh height for first mode of vibration is found to be in agreement the codal values. The combined effect in longitudinal and lateral directions are studied separately, and found that the slosh height is increased by 24.3% and 38.9% along length and width directions respectively. There is no liquid spillage under SSE level of earthquake data in SFSB and TLB at convective level and at free surface acceleration data. Since seismic design codes do not have guidelines for combined excitations and effect of higher modes for irregular geometries, this CFD procedure can be opted for any geometries to study effect of higher modes and combined three directional excitations.

• 한국분무공학회지
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• 제18권1호
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• pp.35-43
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• 2013

The empirical correlations for the prediction of breakup length of liquid jet in uniform cross flow are reviewed and classified in this study. The breakup length of liquid jets in cross flow was normally discussed in terms of the distances from the nozzle exit to the column breakup location in the x and y directions, called as column fracture distance and column fracture height, respectively. The empirical correlations for the prediction of column fracture distance can be classified as constant form, momentum flux ratio form, Weber number form and other parameter form, respectively. In addition, the empirical correlations for the prediction of column fracture height can be grouped as momentum flux ratio form, Weber number form and other parameter form, respectively. It can be summarized that the breakup length of liquid jet in a cross flow is a basically function of the liquid to air momentum flux ratio. However, Weber number, liquid-to-air viscosity ratio and density ratio, Reynolds number or Ohnesorge number were incorporated in the empirical correlations depending on the investigators. It is clear that there exist the remarkable discrepancies of predicted values by the existing correlations even though many correlations have the same functional form. The possible reasons for discrepancies can be summarized as the different experimental conditions including jet operating condition and nozzle geometry, measurement and image processing techniques introduced in the experiment, difficulties in defining the breakup location etc. The evaluation of the existing empirical correlations for the prediction of breakup length of liquid jet in a uniform cross flow is required.

• 한국환경과학회지
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• 제9권5호
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• pp.389-392
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• 2000

In this study a packed tower was selected for the treatment apparatus of $NH_3$ gas produced in industry. Formerly latticework packing has been used in preventive facility of treatment of $NH_3$ gas. However recently metallic Ralu-Pack 250YC. structured packing is usually being used in petrochemical production plant. This study is for the application the packing to the $NH_3$ gas treatment in wet scrubbing process. In Air/water system hydraulic pressure drop dependent of specific liquid load and gas capacity factor was continuous and parallel from graph. The tower height can be determuined by the number of transfer unit and the height of transfer unit influenced on liquid distribution.

• Korean Chemical Engineering Research
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• 제50권5호
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• pp.913-922
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• 2012

환경 및 화학공업에서 액-액 교반조내의 특성을 파악하는 일은 매우 중요하다. 액적 부근의 물질이동용량계수 $k_La$와 Sauter 평균경 $d_{32}$은 에스테르의 알칼리 가수분해반응을 이용하여 임펠러 부착위치나 액높이를 변화시켜 측정하였다. 그 결과 아래와 같은 이들의 양호한 상관식을 얻었다. $$d_{32}=0.270\(\frac{{\sigma}^{0.6}}{{\rho}^{0.2}P^{0.4}_{Vi}}\)k_La=0.49\(\frac{6{\phi}D_A}{d^2_{32}}\)\(\frac{P_Vd^4_{32}}{{\rho}v^3}\)^{0.193}Sc^{1/3}$$.

• 한국자동차공학회논문집
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• 제16권2호
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• pp.93-98
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• 2008

To investigate the characteristics of water droplet on the gas diffusion layer from both top-view and side-view of the flow channel, a rig test apparatus was designed and fabricated with prism attached plate. This experimental device is used to simulate the growth of single liquid water droplet and its transport process with various air flow velocity and channel height. The contact angle hysteresis and height of water droplet are measured and analyzed. It is found that droplet tends towards to be instable by decreasing channel height, increasing flow velocity or making GDL more hydrophobic. Also, the simplified force balance model matches with experimental data only in a restricted range of operating conditions and shows discrepancy as the air flow velocity and channel height increases.

• 대한조선학회논문집
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• 제47권1호
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• pp.38-46
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• 2010

This study aims at investigating the effect of the baffle height on the liquid sloshing in the three-dimensional (3D) rectangular tank. In order to simulate the 3D incompressible viscous two-phase flow in the 3D tank with partially filled liquid, the present study has adopted the volume of fluid (VOF) method based on the finite-volume method which has been well verified by comparing with the results of the relevant previous researches. The ratio of the baffle height ($h_B$) to filling level (h) has been changed in the range of $0{\leq}h_B/h{\leq}1.2$ to observe the effect on the impact loads on the side wall and free surface behavior. Generally, as baffle height increases, the impact pressure on the wall decreases and the deformation of free surface becomes weaker. However it seemed that a critical ratio of the baffle height existed to reveal the lowest impact pressure on the wall. Consequently, $h_B/h=0.8$ among $h_B/hs$ considered in the study showed the lowest impact pressure.

• 설비공학논문집
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• 제16권7호
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• pp.630-638
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• 2004

Liquid desiccant dehumidification systems have the ability to provide efficient humidity and temperature control while saving the electrical energy requirement for air conditioning as compared to a conventional system. The dehumidifier and the regenerator form the heart of this system. The latent part of the cooling load is overcome using liquid desiccant. The model regenerator has been designed to study the absorption characteristic of the aqueous triethylene glycol (TEG) solution which is in the flow range from 20 to 50 LPM. Also, this system designed that was able to change the height of the regenerator and dehumidifier. Because the effect of performance have different result according the height. The effect of performance factors of the regenerator with inlet solution flow rate, air flow rate, solution concentration, solution temperature, brine temperature, air temperature and inlet air relative humidity have been analyzed. Data obtained are useful for design guidance and performance analysis of the hybrid air conditioning system.