• Journal of Environmental Science International
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• v.23 no.10
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• pp.1731-1743
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• 2014

The time variations in relative humidity observed at the Gangjeong (Goryeong) Reservoir in the Nakdong River over a one-year period (September 2012-August 2013) were analyzed with the Bowen ratio. The thermal vertical scale of the reservoir was also evaluated following Yamamoto's method. The study's results showed that the relative humidity at the reservoir was higher than that of the Daegu Meteorological Observatory (inland) all year round. The difference was slightly larger at nighttime (17-20 %) than at daytime (13-15 %) in all seasons except summer. The quantitative order of latent heat flux was summer, spring, autumn, and winter. This finding signifies that the thermal vertical scale of the reservoir corresponds to that of a shallow lake. The Bowen ratio was smallest at midday of the summer season. In other words, the net radiation energy was converted more as latent heat flux than sensible heat flux during a higher temperature period.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.3
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• pp.551-560
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• 1988

Gas-particle two phase flow and heat transfer in a cavity receiving thermal radiation through selectively transparent walls have been analyzed by a finite difference method. Particles injected from the upper hole of the cavity are accelerated downward by gravity and exit through the lower hole while they absorb, emit and scatter the incident thermal radiation. Gas phase is heated through convection heat transfer from particles, and consequently buoyancy induced flow field is formed. Two-equation model with two-way coupling is adopted and interaction terms are treated as sources by PSI-Cell method. For the particulate phase, Lagrangian method is employed to describe velocities and temperatures of particles. As thermal radiation is incident upon horizontally, radiative heat transfer in the vertical direction is assumed negligible and two-flux model is used for the solution of radiative heat flus. Gas phase velocity and temperature distributions, and particle trajectories, velocities and temperatures are presented. The effects of particle inlet condition, particle size, injection velocity and particle mass rate are mainly investigated.

• Journal of the Korean Society of Safety
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• v.20 no.1 s.69
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• pp.68-74
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• 2005

The objective of the present work is to examine the evaporation shape of deposited droplet on the hot surface. this paper performed the experiments as following conditions: (a) the surface temperature is within the range between $80^{\circ}C$ and $95^{\circ}C$ in the conduction and radiation, (b) droplet diameter is 3.0mm. The results are as follows; while droplet evaporates, droplet's radius is kept changelessly to $70\%$ evaporation time and droplet's shape is kept changelessly after. In case use Constant radius model, about $10\%$ is appearing high than value that time-averaged heat flux applies Inverse heat conduction.

• Journal of the Korean Society of Industry Convergence
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• v.6 no.1
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• pp.65-71
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• 2003

Infrared heating has been traditionally used in industrial applications for processes such as dehydration of food industrial. This heating method involves the application of radiation in the wavelength range of 5~50 micrometers. In this work, simultaneous heat balance equations were developed to simulate the infrared radiation heating of red peppers. The equations assume that moisture diffuses to the outer boundaries of the material in liquid form and evaporation occurs at the surface of the red peppers. Energy for moisture evaporation is supplied by the infrared radiant energy. The equations were validated with experimental data on surface temperature and average moisture content of red peppers. Average deviations of predicted surface red peppers temperature and average red peppers moisture from experimental data were 323~353K and 50~80%, respectively. The spectral extinction coefficients in the wavelength range $1.5<{\lambda}<27$ micrometer at 293K for Red Peppers were determined from results of reflection measurements and the four flux radiative heat transfer calculation. The radiation extinction coefficients were obtained from effective drying factor the temperature 373K.

• Korean Journal of Remote Sensing
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• v.11 no.1
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• pp.65-80
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• 1995

Remote Sensing data with ancillary ground-based meteorological data provides the capalility of computing threeof the four surface energy balance components(i.e. net radiation, soil heat flux and sensible heat flux) at different spatial and temporal scales. As a result, this enablis the estimation of the remaining term, latent heat flux. One of the practical applications with this approach is to produce evapotranspiration maps over large areas. This results could estimate and reproduce areal evapotranspiration over large area as much as several hundred sequare kilometers. Moreover, some calculating simulations for the effects of the land use change on the surface heat flux has been made by this method, which is able to estimate evapotranspiration under arbitracy presumed condition. From the simulation of land use change, the results suggests that the land use change in study area can be produce the significant changes in surface heat flux. This preliminary research suggests that the future research should involve development of methods to account for the variability of meteorological parameters brought about by changes in surface conditions and improvements in the modeling of sensible heat transfer across the surface atmosphere interface for partical canopy conditions using remote sensing information.

• Journal of Wetlands Research
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• v.15 no.4
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• pp.509-518
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• 2013

Understanding of the exchange between the water and energy which is happening between the surface and atmosphere is the basic of studying water resources. To study these, lots of researches using Noah Land Surface Model(LSM) are in progress. Noah LSM is based on energy and water balance equation and simulates various hydrological factors. There are diverse researches with Noah LSM are ongoing in overseas, on the other hand not enough study has been done. Especially there is almost no study using uncoupled Noah LSM in Korea. In this study we used data from Korea Flux Tower in Haenam(HFK) and Gwangneung(GDK) as forcing data to simulate the model and compared its result of net radiation, sensible heat flux and latent heat flux with the observation data to assess the applicability of Noah LSM in Korea. Regression coefficients of the comparison results of Noah LSM and observation show good agreement with the value of 0.83~0.99 at Haenam and 0.64~0.99 at Gwangneung which means Noah LSM can be trusted.

• Journal of Korea Water Resources Association
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• v.49 no.6
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• pp.551-563
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• 2016

According to the 4th and 5th assessment of the Intergovernmental Panel on Climate Change (IPCC), global climate has been rapidly changing because of the human activities since Industrial Revolution. The perceived changes were appeared strongly in temperature and concentration of carbon dioxide ($CO_2$). Global average temperature has increased about $0.74^{\circ}C$ over last 100 years (IPCC, 2007) and concentration of $CO_2$ is unprecedented in at least the last 800,000 years (IPCC, 2014). These phenomena influence precipitation, evapotranspiration and soil moisture which have an important role in hydrology, and that is the reason why there is a necessity to study climate change. In this study, Asia region was selected to simulate primary energy index from 1951 to 2100. To predict future climate change effect, Common Land Model (CLM) which is used for various fields across the world was employed. The forcing data was Representative Concentration Pathway (RCP) data which is the newest greenhouse gas emission scenario published in IPCC 5th assessment. Validation of net radiation ($R_n$), sensible heat flux (H), latent heat flux (LE) for historical period was performed with 5 flux tower site-data in the region of AsiaFlux and the monthly trends of simulation results were almost equaled to observation data. The simulation results for 2006-2100 showed almost stable net radiation, slightly decreasing sensible heat flux and quite increasing latent heat flux. Especially the uptrend for RCP 8.5 has been about doubled compared to RCP 4.5 and since late 2060s, variations of net radiation and sensible heat flux would be significantly risen becoming an extreme climate condition. In a follow-up study, a simulation for energy index and hydrological index under the detailed condition will be conducted with various scenario established from this study.

• Fire Science and Engineering
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• v.18 no.4
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• pp.86-92
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• 2004

We tested five specimens of each species at each of five constant external heat flux levels (10, 15, 20, 25. and 35㎾/㎡). An Cone heater was used to expose the wood specimens to the heat flux. The 100-by 100-by 50-㎜ specimens were of four species: Redwood, White oak, Douglas fir, Maple. In result of test, charring of wood exposed to a constant external heat flux can be considered a linear with function of time. As compared with the charring rates Redwood is most rapidly, but on the other hand Douglas fir is most slowly. When the external heat flux is 35㎾/㎡, the charring rate is rapidly about twice then 10㎾/㎡. Using the Equation (2), the estimates for u were 1.02, 1.16, 1.23, 1.32, and 1.44 for the 10, 15, 20, 25, and 35 kw/m2 constant external exposure levels, respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.2 no.1
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• pp.1-9
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• 1992

Radiation heat transfer was calculated for initial stage of crystal growth in Czochralski crystal growth system. View factors among surface elements were calculated for the estimation of heat evolution and all the surfaces were assumed to be diffuse-gray. The values of view factors were greatly different along the position of surface elements. The dissipated amounts of heat flux from the melt surface were 3.6 times larger than those from the crystal surface at the initial stage of crystal growth and this amounts were greater when the surface elements were not considered. The trijunction part of the crystal was greatly affected by the melt surface near the crystal. Consequently radiation heat transfer between surface elements must be considered in order to correctly simulate the initial crystal growth.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.1
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• pp.131-136
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• 2008

The double-walled steel vessel with powder insulation in the space between the walls is used to minimize heat transfer by radiation and conduction in cryogenic storage tank. The vacuum required the insulation is much less extreme than with high-vacuum or multilayer insulations. The solid supports are used to bear the weight of the inner container. Thermal and structural analysis of the tank have been carried out to study the effect of vacuum and weldment geometry of the internal supports. Heat flux in wall is increased with increasing of thermal conductivity of perlite. Heat flux and stress of support is not affected by weldment geometry.