• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.7
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• pp.385-389
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• 2017

Generally, refrigerant temperature out of the receiver is assumed to be saturated. This may be true for horizontal or vertical receivers having small aspect ratio. However, this assumption needs verification for vertical receiver having large aspect ratio. No study has reported information on this issue. The objective of this study was to determine the effect of liquid level and mass flow rate on liquid subcooling of a long vertical receiver using R-410A. During the test, inlet subcooling was maintained at $5^{\circ}C$ while saturation temperature was maintained at $10^{\circ}C$. Results showed that subcooling was maintained for the long vertical receiver. Subcooling preservation ratio (ratio of exit to inlet subcooling) was increased as mass flow rate or liquid level was increased. As a whole, 50 to 70% subcooling preservation was possible for the present receiver. Further investigations are needed to enhance information on this issue using receivers having different aspect ratios.

• Journal of Chest Surgery
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• v.13 no.2
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• pp.85-91
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• 1980

Extracorporeal circulation by hemodilution technique has been currently used with its clinical safety and good peripheral tissue perfusion in open heart surgery. There is no doubt that $O_{2}$ carrying capacity of the blood is disturbed by decreased hemoglobin level resulting from hemodilution of the circulating blood. From the view point of the blood gas exchange, these experimental studies were undertaken to determined the sate limit of hemodilution in the condition of cardiopulmonary bypass with a constant perfusion flow rate. Twelve adult mongrel dogs weighing 10 to 13 Kg. were anesthetized with pentobarbital and then respiration was controlled with Harvard volume respirator using room air. The cardiopulmonary by pass was performed by use of Sarns heart lung machine (console 5000, 5 head and 2 roller pumps) and Travenol pediatric bubble oxygenator. The perfusion rate during bypass was maintained at a constant rate of 80 ml/min/Kg of body weight. The ratio of oxygen gas flow to blood flow was kept in 3 to 1 constantly. International hemodilution was attained by serial blood withdrawals and immediate infusion of equal volumes of diluants composed of Ringer's lactate, 5% dextrose in water and 25% mannitol solution, proportionally 60%, 30%, and 10%. Arterial and venous blood samples were obtained between 15 and 20 minutes following each hemodilution. Hematocrits and hemoglobin values, $PO_{2}$, $PCO_{2}$ and pH were measured. Oxygen and carbon dioxide contents oxygen consumption and carbon dioxide elimination were calculated groups according to different hematocrit values and the correlations were evaluated. Result were as follows. 1. the arterial $O_{2}$ tension and $O_{2}$ saturation were maintained at the physiological level irrespective of the hematocrit value. 2. The venous $O_{2}$ tension and $O_{2}$ saturation showed a tendency to decline with the decrease in hematocrit value and positive correlation between them (r = +0.49, r = +0.76), The mean values of venous $O_{2}$ tension and $O_{2}$ saturation, however, were not decreased when the hematocrit levels were lower than 20%. 3. The arterial $O_{2}$ content declined lineally in proportion to the fall of hematocrit level with a positive correlation between them (r = +0.95). 4. The venous $O_{2}$ contents were decreased gradually as the hematocrit value decreased with positive correlation between them ( r =+0.89). The trend of diminution of venous $O_{2}$ content, however, was became low according to progressive decrease of hematocrit level. 5. Systemic oxygen consumption was in higher range than $O_{2}$ requirement of basal metabolism when the hematocrit value was above 20%, but abruptly decreased when the hematocrit value became to below 20%. 6. The arterial $CO_{2}$ tension and $CO_{2}$ content showed trend of increasing with progressive decrease of hematocrit value but exhibited a rather broad range and there was no relationship between those value and the hematocrit value. 7. The venous $CO_{2}$ tension and $CO_{2}$ content have also no correlation with change of Ht. value but related directly to those value of arterial blood with positive correlation between them (r = +0.78, r = +0.95_. 8. A-V difference of $CO_{2}$ content and $CO_{2}$ elimination wasnot significantly influenced by Ht. value. From the results, we obtained that feasible limit in inteneional hemodilution is above the hematocrit value of 20% under the given experimental condition.

• Journal of the Korean Magnetics Society
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• v.18 no.1
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• pp.14-18
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• 2008

Bismuth-substituted yttrium iron garnet(Bi:YIG) films, which show excellent magnetic and magneto-optical properties as well as low optical losses by optimizing their deposition and post-annealing condition, have been attracting great attention in optical device research area. In this study, the Bi:YIG thick films were deposited with the aerosol deposition method for the final purpose of applying them to optical isolators. Since the aerosol deposition is based on the impact adhesion of sub-micrometer particles accelerated by a carrier gas to a substrate, the flow rate of carrier gas, which is in proportion to mechanically collision energy, should be treated as an important parameter. The Bi:YIG($Bi_{0.5}Y_{2.5}Fe_5O_{12}$) particles with $100{\sim}500$ nm in average diameter were carried and accelerated by nitrogen gas with the flow rate of 0.5 l/min${\sim}$10 l/min. The coercive force decreased from 51 Oe to 37 Oe exponentially with increasing gas flow rate. This is presumably due to the fact that the optimal collision energy results in reduction of impurity and pore, which makes the film to be soft magnetically. The saturation magnetization decreased due to crystallographical distortion of the film with increasing gas flow rate.

• Journal of Soil and Groundwater Environment
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• v.19 no.3
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• pp.111-122
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• 2014

Partitioning interwell tracer test (PITT) is a method to quantify and qualify a site contaminated with NAPLs (Non-Aqueous Phase Liquids). Analytical description of PITT assumes that the injection-pumping well pair is on the line of the ambient groundwater flow direction, but the test-well pair could frequently be off the line in a real field site, which could be an erroneous factor in analyzing PITT data. The purpose of this work is to study the influence of the angle of the test-well pair on the ambient groundwater flow direction based on the result from PITT. From the experiments, it was found that the obliqueness of the test-well pair to the ambient groundwater flow direction could affect the tracer test resulting in a decreased NAPL estimation efficiency. In case of an oblique arrangement of the test-well pair to the ambient flow direction, it was found that the injection of a chase fluid could enhance the estimation efficiency. An increase of the pumping rate could enhance the recovery rate but it cannot be said that a high pumping rate can increase the test efficiency because a high pumping rate cannot give partitioning tracers enough time to partition into NAPLs. The results have a implication that because the arrangement of the test-well pair is a controlling factor in performing and interpreting PITT in the field in addition to the known factors such as heterogeneity and the source zone architecture, flow direction should be seriously considered in arranging test-well pair.

• Journal of Soil and Groundwater Environment
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• v.6 no.1
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• pp.45-52
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• 2001

This study investigated the effectiveness of ultrasonic waves on the relative permeability under a range of soil type, flushing rate, and sonication power. This study was conducted in the laboratory using a specially designed and fabricated equipment, and the laboratory study was simulated by ECLPISE 100 which is a commercial black oil simulator. The test results indicated the sonication increased contaminant extraction significantly. From analytical standpoint, sonication caused a change in the relative permeability of the test samples, a reduction in residual oil saturation and an increase in both irreducible water saturation and wettability. These three parameters are highly related with $(C_{10})^2$. The computer software ECLIPSE 100 can be used to analyze the change of the relative permeability due to sonication in two phase immiscible flow.

• Journal of fish pathology
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• v.36 no.2
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• pp.379-388
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• 2023

Experiments were performed to investigate hypoxia tolerance with body size of red seabream (Pagrus major) at 24℃. The rate of oxygen consumption was measured at an interval of 10 min using automated intermittent-flow respirometry. The weight-specific standard metabolic rate (SMR, mg O₂ kg^-1hr^-1) and critical oxygen saturation (S_crit, % air saturation) of the fish were measured under normoxic condition and progressive hypoxia with 0.6-786 g of fish weight (W), respectively. SMR typically decreased with increasing body weight based on SMR=351.59·W^-0.195 (r²=0.934). S_crit was higher in larger fish than those of smaller fish in the range of 17.3-24.4%. The result of this study suggests that the smaller seabream can withstand in hypoxic waters better than the larger ones.

• Journal of Powder Materials
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• v.9 no.5
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• pp.322-328
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• 2002

Fe-Co nanocomposite powders with different composition were prepared by chemical vapor condensation (CVC) process and their characterizations were studied by means of X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer. The particles having the mean size of 5~25 nm consisted of metallic cores and oxide shells. The Co contents and particle size increased with increasing the carrier gas flow rate of Co precursor. The saturation magnetization and coercivity increased with increasing Co content. and the saturation magnetization maximized at the 40 wt.%Co. The Fe-Co nanocomposite powder oxidized at $400^{\circ}C$ showed the maximum coercivity of 1739 Oe.

• Journal of Environmental Science International
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• v.30 no.8
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• pp.613-619
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• 2021

Soil water enters the atmosphere via evapotranspiration, where it transforms into atmospheric water vapor and plays important role in the surface-atmosphere energy exchange. Soil conditions have a direct influence on the effective rainfall, and initial soil moisture conditions are important for quantitatively evaluating the effective rainfall in a watershed. To examine the sensitivity of the initial saturation to hydrologic outflow, a two-dimensional distributed FLO-2D hydrologic model was applied to a small watershed. The initial saturation was set to 0.3, 0.5, and 0.7 and the obtained results were compared. The Green-ampt model was chosen to calculate the penetration loss. Depending on the initial soil moisture, the peak flow rate varied by up to 60%, and the total water volume in the watershed by approximately 40%.

• Nuclear Engineering and Technology
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• v.51 no.6
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• pp.1532-1539
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• 2019

This paper analyzes a new method for reducing boiling water reactor fuel temperature during a Loss of Coolant Accident (LOCA). The method uses a device called Reverse Flow Restriction Device (RFRD) at the inlet of fuel bundles in the core to prevent coolant loss from the bundle inlet due to the reverse flow after a large break in the recirculation loop. The device allows for flow in the forward direction which occurs during normal operation, while after the break, the RFRD device changes its status to prevent reverse flow. In this paper, a detailed simulation of LOCA has been carried out using the U.S. NRC's TRACE code to investigate the effect of RFRD on the flow rate as well as peak clad temperature of BWR fuel bundles during three different LOCA scenarios: small break LOCA (25% LOCA), large break LOCA (100% LOCA), and double-ended guillotine break (200% LOCA). The results demonstrated that the device could substantially block flow reversal in fuel bundles during LOCA, allowing for coolant to remain in the core during the coolant blowdown phase. The device can retain additional cooling water after activating the emergency systems, which maintains the peak clad temperature at lower levels. Moreover, the RFRD achieved the reflood phase (when the saturation temperature of the clad is restored) earlier than without the RFRD.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.6
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• pp.674-682
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• 1998

In this study, thin film evaporation of water on low-fin tubes were experimentally investigated. Five low-fin tubes with different fin spacing and fin height were tested. Test range covered 0.146kg/ms $\leq$$\Gamma$$\leq$0.219kg/ms and 10㎾/$\m^2$$\leq$q $\leq$70㎾/$\m^2$. Saturation temperature was loot. Compared with the plain tube, low fin tubes enhanced the water film evaporation from 60% to 100%. Tubes with fin spacing smaller than 2mm and fin height higher than 1mm performed better than tubes with other fin configuration. However, when fin spacing was too small at high film flow or fin height was too high at low film flow, the performance decreased. The heat transfer coefficient slightly increased as the flow rate increased. Correlations are developed based on present data.