• Journal of Integrative Natural Science
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• v.6 no.1
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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.

• Journal of the Korean earth science society
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• v.33 no.3
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• pp.233-241
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• 2012

Based on the observation of the microwave radiometers at Cheongju, Hapcheon and Daegwallyeong in Korea, the precipitable water vapor and liquid water path have been analyzed for spatio-temporal characteristics. The observed datas have been validated by comparing precipitable water vapor between the microwave radiometer and the radiosonde near the sites. It resulted in the correlation coefficient of more than 0.8 in all three sites. For three regions, the precipitable water vapor shows similar seasonal variation and diurnal cycle, and that amount of precipitable water vapor increases from around 1000 LST and has a maximum value at 1900 LST. On the other hand, the liquid water path of microwave radiometer has regional differences for its seasonal variation, which seems to be caused by the geographical characteristics including the frequent fog and clouds in Daegwallyeong, a high mountain region (834 m from sea level), almost flat land in Chengju, and Sobaek Mountains in Hapcheon that blocks the westerly clouds.

• Atmosphere
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• v.20 no.1
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• pp.1-12
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• 2010

Temporal distributions and characteristics of PWV (Precipitable Water Vapor) and LWP (Liquid Water Path) are investigated by using the microwave radiometric profiler at Haenam NCIO from 1 August 2007 to 31 July 2008. Temporal variations of PWV are closely connected with the thermal response of water vapor in atmosphere. The variations of LWP are characterized by the rainfall variation being basically attributable to the heavy rain-bearing clouds. The frequency distributions of PWV and LWP according to the four sky conditions ('clear', 'lightly cloudy', 'cloudy', and 'deeply cloudy') by total cloud amount at Wando Observatory corresponds with a change of slope in cumulative distribution function for PWV and LWP. There results implies that the classification of sky condition can be applied by using the distribution of PWV and LWP from microwave radiometric profiler.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.2
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• pp.235-247
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• 2006

Aerosol indirect radiative forcing of climate change is considered the most uncertain forcing of climate change over the industrial period, despite numerous studies demonstrating such modification of cloud properties and several studies quantifying resulting changes in shortwave radiative fluxes. Detection of this effect is made difficult by the large inherent variability in cloud liquid water path (LWP): the dominant controlling influence of LWP on optical depth and albedo masks any aerosol influences. Here we have used ground-based remote sensing of cloud optical depth (${\tau}_c$) by narrowband radiometry and LWP by microwave radiometry to determine the dependence of optical depth on LWP, thereby permitting examination of aerosol influence. The method is limited to complete overcast conditions with liquid-phase single layer clouds, as determined mainly by millimeter wave cloud radar. The results demonstrate substantial (factor of 2) day-to-day variation in cloud drop effective radius at the ARM Southern Great Plains site that is weakly associated with variation in aerosol loading as characterized by light-scattering coefficient at the surface. The substantial scatter suggests the importance of meteorological influences on cloud drop size as well, which should be analyzed in the further intensive studies. Meanwhile, it is notable that the decrease in cloud drop effective radius results in marked increase in cloud albedo.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.674-679
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• 1998

Small water leak experiment was carried out in liquid sodium atmosphere using a specimen of ferrite steel, which will be expected to be a material of the heat transfer tube of liquid metal fast breeder reactor. Self-plugging phenomena of leak path could be explained by the products of reaction and corrosion by sodium-water reaction. Also, re-opening mechanism of self-plugged path could be explained by the thermal transient and vibration of heat transfer tube. As a result, perfect re-opening time of self-plugged leak path was observed to be 129 minutes after water leak initiation. Re-opening shape of a specimen was appeared with double layer of circular type, and re-opening size of this specimen surface was about 2 mm diameter on sodium side.

• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.268-272
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• 1998

Water leak phenomena in the liquid sodium which is a coolant of liquid metal reactor, were investigated by carrying out sodium-water reaction experiment. It was confirmed that sodium and water react each other by the analysis of material composition of aspecimen at the end of experiment. When steam of $100kg/cm^2$ was passed through the leak path of the specimen for 4 hours, reaction products from sodium-water reaction were observed on the leak site. However, re-opening phenomena were not observed at this condition. It was interpretted that the reaction product precipitated on leak path and thermal transient caused self-plugging and re-openning phenomena, respectively.

• Journal of the Korean earth science society
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• v.40 no.2
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• pp.109-118
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• 2019

Cloud-aerosol interactions are considered to be one of the most important forcing mechanisms in the climate system. However, there is considerable disagreement on the magnitude and even on the sign of how aerosol perturbations affect cloud fraction and lifetime. Furthermore, aerosol effects on clouds and precipitation are not readily separable from the effects of meteorology. This review paper summarizes the study of precipitation susceptibility $S_o$, which qualifies how aerosol perturbations alter the magnitude of the precipitation rate (R) while minimizing the effects of macrophysical factors such as cloud depth (H) and liquid water path (LWP). The analysis shows that the precipitation susceptibility $S_o$ for the warm marine boundary layer clouds is insensitive to aerosol perturbations at low LWP (equivalently low H). However, R decreases as aerosols increase at intermediate LWP. This is because aerosols act as cloud seed and produce numerous small-sized particles, which impede the collision and coalescence process that leads to precipitation. At high LWP, $S_o$ decreases with increasing LWP as there are enough water contents in the clouds. The LWP or H dependent $S_o$ behavior differs depending on the predominant cloud physics processes in the clouds.

• Nuclear Engineering and Technology
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• v.37 no.6
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• pp.557-564
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• 2005

Air-water countercurrent flow limitation at perforated plates with four holes was investigated in a vertical tank to see the effects of the plate thickness, the number of hole, and the diameter of the hole on the onset of CCFL. The thickness of plates was 1 cm and 4 cm, with a relatively large hole diameter of 5 cm. The collapsed water level formed on the perforated plate and its distribution in the upper plenum were measured. The gas flow rate in the multi-hole plate is relatively higher than one in the single tube because some of holes in the multi-hole plate provide a flow path fur liquid with less air-liquid resistance than in the single tube. The onset of CCFL occurred at nearly the same air flow rate regardless of the plate thickness. The negligible effect of the plate thickness on CCFL means that the flooding is initiated at the top of the plate rather than at its bottom. It turns out that $j_k$ and $K_k$ better fit the data than $H_k$ when hole diameter is greater than 2.86 cm. In our experimental ranges, the collapsed water levels at the onset of CCFL ranged from 7.5 cm to 10.5 cm. There was no three dimensional distribution of water level before and after the onset of CCFL.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1306-1311
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• 2004

The performance test apparatus of liquid-phase plate heat exchanger was installed and the computer program for design was developed in this study. The detail temperature distribution of hot and cold fluids in each path of heat exchanger was calculated by numerical method and the correlation for the heat transfer coefficient was defined. The heat transfer coefficients were measured using the working fluids of water and glycerine to investigate the effect of fluid viscosity. The measured heat transfer coefficients were compared with the calculated values obtained from the computer program and it was shown that error of the calculated values was generally less than 5%.

• Journal of the Korean Wood Science and Technology
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• v.36 no.5
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• pp.49-55
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• 2008

This study was carried to investigate the effects of steaming and four different drying methods on the longitudinal liquid permeability of Korean pine (Pinus koraiensis Sieb.et Zucc.) board. Four drying methods were air drying, conventional kiln drying, microwave-vacuum drying and high temperature drying. Darcy equation was used for calculating the specific permeability of the small sapwood specimens taken from the treated boards while capillary rising method was used for the heartwood specimens. The sapwood specimens were extracted with water and benzene-alcohol solution to examine the mechanism of liquid flow in treated wood. No significant correlation was found between specific permeability and the number of resin canals of the sapwood specimens. Extraction decreased the differences of specific permeabilities of the sapwood specimens between the five treatment methods. The effects of extraction on the longitudinal permeability are different between five treatments. The fluid path in heartwood was observed by dynamic observation method.