• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.11 no.6
• /
• pp.709-715
• /
• 1999

To optimize a heating and cooling system, we need an exact solution lot radiant heat transfer in any form of room or building. This paper describes the solution method of view factor by the area weighted average and graphical method to calculate the radiant heat exchange or daylighting level in any form of room or building. This study shows that the area weighted average and graphical methods have many points of merits(calculation speed, correctness and calculation capability in an arbitrary form of room shapes etc.) compared with existing methods

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.36 no.5
• /
• pp.535-540
• /
• 2003

Based on the monthly weather report of Korea Meteorological Administration (KMA) and daily sea surface temperature (SST) data from National Fisheries Research and Development Institute (NFRDl) (1991-2001), mean heat fluxes were estimated at the Gunsan harbor Net heat flux was transported from the air to the sea surface during March to early September, and it amounts to $125\;Wm^{-2}$ in average daily during May to June. During the middle of September to February, the transfer of net heat flux was conversed from the sea surface to the air with $-125\;Wm^{-2}$ in mininum value in October. Short wave radiation was ranged from 50 to $248\;Wm^{-2}$ showing maxima in April to June. Long wave radiation was ranged from 25 to $92\;Wm^{-2}$ with mininum value in June to July. Sensible heat flux denoting negative values in April to August was ranged from -30 to $72\;Wm^{-2}.$ Latent heat flux was ranged from 15 to $82\;Wm^{-2}$ with maxima in August to September. The phase of heat exchange was changed from cooling to heating in the end of February, and from heating to cooling In the beginning of September. The advective term of heat flux showed minima in April to June and maxima in November. The ratio of temperature variations was 1.37 in the sea surface process and the horizontal process by advection. This indicates that the main factor in variation of temperature at Gunsan harbor is the heat exchange process through the sea surface from the air.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.45 no.8
• /
• pp.678-685
• /
• 2017

The radiator of the data storage and handling units onboard the earth observation satellite is a groove-type radiator covered with a shield because of the periodic high heat dissipation and design characteristics of arrangement and mountability of the unit. The effect of the groove-type radiator and that of the shield versus plane radiator were verified through the thermal vacuum test. Through the test result, the temperatures of the radiator and the heat exchange due to the view factor were analyzed by using the analytical method. Conclusively the thermal performance of the shield dissipation plate was verified.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.23 no.3
• /
• pp.352-363
• /
• 1999

Target detection by the infrared imager depends on the apparent temperature difference between the target and the background, so it is essential to predict apparent temperature variations for this purpose. In this study, thermal analysis program Including conduction, convection and radiation is developed and applied to a representative geometry adequate for examining the apparent temperature characteristics. The results show that the longwave emissivity in association with the background temperature affects the apparent temperature strongly but does not affect the physical temperature. It is revealed that the background temperature plays a role of tuning the apparent temperature. As the longwave emissivity decreases, the apparent temperature decreases when the target is hotter than the background, whereas it increases in the reversed situation. These findings imply that an effective surface treatment, such as painting of a less emissive material, may provide a less detection probability and contribute to preventing the target from being detected at night.

• Journal of Radiation Protection and Research
• /
• v.24 no.2
• /
• pp.73-86
• /
• 1999

The ion-exchange method for the purification of primary coolant has been used broadly in PWR(pressurized water reactor)-type nuclear power plants due to its high decontamination efficiency, simple system, and easy operation. However, its non-selective removal of metal and non-radionuclides shortens its life, resulting in the generation of a large amount of waste ion-exchange resin. In this study, the feasibility of electrodeionization (EDI) was investigated for the purification of primary cooling water using synthetic solutions under various experimental conditions as an alternative method for the ion exchange. The results shows that as the feed flow-rate increased, the removal efficiency increased and the power consumption decreased. The removal rate was observed as a 1000 decontamination factor(DF) at a nearly constant level. For the synthetic solution of 3 ppm TDS (Total Dissolved Solid), the power consumption was 40.3 mWh/L at 2.0 L/min of feed flow rate. The higher removal rate of metal species and lower power consumption were obtained with greater resin volume per diluting compartment. However, the flow rate of the EDI process decreased with the elapsed time because of the hydrodynamic resistivity of resin itself and resin fouling by suspended solids. Thus, the ion-exchange resin was replaced by an ion-conducting spacer in order to overcome the drawback. The system equipped with the ion-conducting spacer resolved the problem of the decreasing flow rate but showed a lower efficiency in terms of the power consumption, the removal rate of metal species and current efficiency. In the repeated batch operation, it was found that the removal efficiency of metal species was stably maintained at DF 1000.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.9 no.1
• /
• pp.9-23
• /
• 1997

A numerical study of a two-layer, stratified flow is investigated, using the implicit finite difference method in one dimension. The results of computational method have been tested and, in case of lock exchange flow, compared with the results of experimental data. The results of model experiments with various interfacial, bottom friction coefficients along with various time weighting factor of numerical scheme and dissipative interface are shown and discussed. Two-layer model experiment has been also carried out to investigate the generation and propagation characteristics of internal tidal wave over the steep bottom topography under stratified condition. The internal wave seems to well radiate through the downstream boundary under the experiments adopting radiation conditions both at two layers and only at upper layer, confirming the applicability of radiational boundary condition in stratified flows. It is also shown that the internal wave through the downstream boundary propagates more actively with increasing thickness of lower layer in the downstream. This implies that the potential tidal energy in the interface will depend upon the thickness of lower layer for the constant thickness of upper layer.

• Journal of Radiation Protection and Research
• /
• v.2 no.1
• /
• pp.24-30
• /
• 1977

Les eaux de $g\'{e}n\'{e}rateur$ de vapeur d'un $r\'{e}acteur$ P. W. R peuvent $\^{e}tre$ $contamin\'{e}es$ par des $radio-\'{e}lements$. Ces eaux sont habituellement $condition\'{e}es$ 'phosphate' pour limiter leur $agressivit\'{e}$ et la tendence actuelle est de remplacer les phosphate par un conditionment 'Amoniaques'. La $pr\'{e}sente$ $\'{e}tude$ a pour but de definir la $possibilit\'{e}$ $d'{\'{e}}purer$ des eaux $condition\'{e}es$ $\'{a}$ l'ammoniaque $\'{a}$ l'aide $d'{\'{e}}changeurs$ d'ion organiques. Des Facteurs de $D\'{e}contamination$ (F. D) en Cesium 137 et Strontium 90 et la $dur\'{e}e$ du cycle $d'{\'{e}}puration$ ont $d\^{u}$ $\^{e}tre$ bien meilleurs avec une colonne de 10 ml de $r\'{e}sine$ Carborylique Duolite $CC_4$ mise sous forme acide, suivie d'une colonne de 10 ml de $r\'{e}sine$ cationique Amberlite IR 120 mise sous forme acide et suivie d'une colonne de 10 ml de $r\'{e}sine$ anionique Amberlite IRA 400 mise sous forme hydroxyde.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2003.11a
• /
• pp.54-59
• /
• 2003

Several radionuclides are considered as an object of the assesment to develop a scaling factor and a periodical verification method which are needed for the evaluation of radionuclide inventory of various radioactive wastes from nuclear power plants in Korea. A selective separation of $^{55}Fe$, $^{90}FSr$ 및 $^{94}Nb$ which should be recovered individually for the radiochemical analysis was described in detail. Sorption and desorption behaviours of ion exchange and extraction chromatographic resins for Fe, Sr, Nb and co-existing metal ions were Investigated using an artificial waste solution simulated of chemical composition of real radioactive wastes. Separation conditions available for the sequential recovery of these metal ions from a single sample were optimized to minimize a discharge of radioactive wastes produced through the analytical process and a radiation exposure to analysts. Their recovery yields were measured with reliability.

• Journal of Climate Change Research
• /
• v.5 no.1
• /
• pp.71-81
• /
• 2014

Using the Eddy Covariance technique, we analyzed seasonal variation in net ecosystem $CO_2$ exchange (NEE) and investigated the effects of environmental factors and aboveground biomass of rice on the $CO_2$ fluxes in a rice-barley double cropping paddy field of Gimje, Korea. Quality control and gap-filling were conducted before this investigation of the effects. The results have been showed that NEE, gross primary production (GPP), and ecosystem respiration (Re) during the rice growing period were -215.6, 763.9, and $548.3g\;C\;m^{-2}$, respectively. Relation between NEE and net radiation (Rn) could be described by a quadratic equation, and about 65 % of variation in NEE was explained by changes in Rn. On the other hand, an exponential function relating Re to soil temperature accounted for approximately 43 % of variation in Re under the flooded condition of paddy field. Aboveground biomass showed significant linear relationships with NEE ($r^2=0.93$), GPP ($r^2=0.96$), and Re ($r^2=0.95$), respectively.

• Korean Journal of Environmental Agriculture
• /
• v.18 no.2
• /
• pp.164-168
• /
• 1999

For investigating transfer factors of $^{137}Cs$ in the arable land of Korea, mature crop plants and topsoils were collected from paddy and upland fields located at 33 areas of the country and $^{137}Cs$ concentrations were measured by ${\gamma}-spectrometry$. The $^{137}Cs$ concentrations in soil were in the range of $0.7{\sim}17.7$ Bq/kg-dry in the paddy fields and $1.2{\sim}27.8$ Bq/kg-dry in the upland fields. The $^{137}Cs$concentrations in hulled seed, detected for 12 areas only, were in the range of $0.019{\sim}0.111$ Bq/kg-dry and those in Chinese cabbage, detected also for 12 areas only, were in the range of $0.012{\sim}0.066$ Bq/kg-fresh. Soil-to-plant transfer factors of $^{137}Cs$ were in the range of $1.2{\times}10^{-3}{\sim}1.1{\times}10^{-2}$ for hulled seed and $6.8{\times}10^{-4}{\sim}1.7{\times}10^{-2}$ for Chinese cabbage. Inboth plant stuffs, the factor tended to decrease with increasing soil organic matter or cation exchange capacity and, in hulled seed, it tended to increase with increasing soil clay content. No statistical significance was, however, found in all those relationships. Present results can be utilized for estimating radiation risk resulting from the food consumption by Korean people and deciding agronomical counter-measures at the time of an nuclear accident.