• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.579-582
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• 2003

Ozone is usually generated from oxygen gas using a silent discharge apparatus and its concentration is less then 10 mol%. Ozone is condensed by the adsorption method, which is widely used for the growth of oxidation thin films such as superconductor. Highly condensed ozone is analyzed by three methods; ultraviolet absorption, thermal decomposition and Q-mass analyzing methods. Thermal decomposition method is most effective in the highly condensed ozone region and its method is superior to Q-mass analyzer for determining ozone concentration because of the simplicity of the method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.331-332
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• 2005

Ozone is ambient gas which is useful for the fabrication of metal oxide thin films under conditions of molecular beam epitaxy. Ozone is condensed by the adsorption method and its concentration is analyzed using the thermal decomposition method. The concentration of ozone exceeds 90 mol% and ozone is supplied for a sufficiently long time to grow oxide thin films. The ozone concentration is also evaluated using a quadrupole mass analyzer and the accuracy of this method is compared with the results of the thermal decomposition method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.264-267
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• 2002

An ozone condensation system is evaluated from the viewpoint of an ozone supplier for oxide thin film growth. Ozone is condensed by the adsorption method and its concentration is analyzed by three methods; ultraviolet absorption, thermal decomposition and Q-mass analyzing methods. Thermal decomposition method is found to be available to the concentration evaluation from dilution to highly condensed ozone. The highest ozone concentration condensed by the adsorption method is evaluated to be 97 mol%

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1230-1233
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• 2004

Ozone is useful oxidizing gas for the fabrication of oxide thin films. Accordingly researching on oxidizing gas is required. In order to obtain high quality oxide thin films, higher ozone concentration is necessary. In this paper oxidation property was evaluated relation between oxide gas pressure and inverse temperature(CuO reaction). The obtained condition was formulated by the fabrication of Cu metal thin film by co-deposition using the ion Beam Sputtering method. Because the CuO phase peak appeared at the XRD evaluation of the CuO thin film using ozone gas, this study has succeeded in the fabrication of the CuO phase at $825^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04a
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• pp.35-38
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• 2004

Ozone is useful oxidizing gas for the fabrication of oxide thin films. Accordingly researching on oxidizing gas is required. In order to obtain high quality oxide thin films, higher ozone concentration is necessary. In this paper oxidation property was evaluated relation between oxide gas pressure and inverse temperature(CuO reaction). The obtained condition was formulated by the fabrication of Cu metal thin film by co-deposition using the Ion Beam Sputtering method. Because the CuO phase peak appeared at the XRD evaluation of the CuO thin film using ozone gas, this study has succeeded in the fabrication of the CuO phase at $825^{\circ}C$.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.3
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• pp.24-32
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• 1993

Experimental data on the heat transfer characteristics of HCFC-123 and CFC-11 during condensation in horizontal smooth tube are presented. The experimental apparatus consisted of a closed working fluid loop, coolant loop, and measuring system. The major components of the working fluid loop made of a refrigerant pump, boiler, superheater, refrigerant flow meter, receiver and test section. The tube-in-tube type test section was made of smooth tube which were constructed form 9.52 mm outer diameter of smooth copper tube with 50 mm outside diameter of PVC tube duct. The ranges of parameter, such as refrigerant mass velocity, coolant flow rate, and quality were 90-325kg/($m^2$.s), 60-360kg/h, 5-95% respectively. Data were obtained under steady state condition for annular flow. As a result of these, the condensation heat transfer coefficients for HCFC-123 were slightly lower than those of CFC-11 from 8% to 15% inside horizontal smooth tube. Furthermore, a new generalized correlation for the heat transfer coefficients of HCFC-123 and CFC-11 during condensation inside horizontal smooth tube is proposed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.8
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• pp.555-562
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• 2007

In this study, condensation heat transfer coefficients (HTCs) of R22, R134a, R245fa and R123 are measured on a horizontal plain tube. All data are taken at the vapor temperature of $39^{\circ}C$ with a wall subcooling temperature $3-8^{\circ}C$. Test results show the HTCs of newly developed alternative low vapor pressure refrigerant, R245fa, on a plain tube are 9.5% higher than those of R123 while they are 3.3% and 5.6% lower than those of R134a and R22 respectively. Nusselt's prediction equation for a plain tube underpredicts the data by 13.7% for all refrigerants while a modified equation yielded 5.9% deviation against all data. From the view point of environmental safety and condensation heat transfer, R245fa is a long term good candidate to replace R123 used in centrifugal chillers.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.11
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• pp.1470-1477
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• 2000

Due to the ozone depletion and global warming potentials, some refrigerants(CFx and HCFCs) have been rapidly substituted. R410A is considered as the alternative refrigerant of R22 for the air-conditioners used a home and in industry. Experiments on the condensation heat transfer characteristics inside a smooth or a micro-fin tube with R410A are performed in this study. The test tubes 7/9.52 mm in outer diameters and 3 m in length are used. Varying the mass flux of the refrigerant and the condensation temperatures, the average heat transfer coefficients and pressure drop are investigated. It is shown that the heat transfer is enhanced and the amount of pressure drops are larger in the microfin tube than the smooth tube. From the heat transfer enhancement coefficient and the pressure penalty factor, it is found that the high heat transfer enhancement coefficients are obtained in the range of small mass flux while the penalty factors are almost equal.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.2
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• pp.87-96
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• 2008

Flow condensation heat transfer coefficients(HTCs) of R123 and R245fa are measured in a horizontal plain tube. The main test section in the experimental flow loop is made of a plain copper tube of 9.52 mm outside diameter and 530 mm length. The refrigerant is cooled by passing cold water through an annulus surrounding the test section. Tests are performed at a fixed saturation temperature of $50\;{\pm}\;0.2\;^{\circ}C$ with mass fluxes of 50, 100, $150\;kg/m^2s$ and heat flux of $7.3{\sim}7.7\;kW/m^2$. Heat transfer data are obtained in the vapor quality range of $10{\sim}90%$. Test results show that the flow condensation HTCs of R245fa are overall 7.9% higher than those of R123 at all mass fluxes. The pressure drop of R245fa is smaller than that of R123 at the same heat flux. In conclusion, R245fa is a good candidate to replace ozone depleting R123 currently used in chillers from the view point heat transfer and environmental properties.

• Journal of Hydrogen and New Energy
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• v.27 no.4
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• pp.462-469
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• 2016

This paper presents the results of thermodynamic cycle analysis and performance tests of alternative mixtures in low temperature applications. Two near-azeotropic binary mixtures R-152a/R-1270 (35:65 by wt.%) and R-290/E170 (35:65 by wt.%) are considered in this study. They have zero ODP (Ozone Depletion Potential) and much lower GWP (Global Warming Potential) than R-404A which is an alternative of R-502. Refrigeration cycle characteristics such as cooling capacity, coefficient of performance, suction and discharge pressures and temperatures are compared to those for the baseline refrigerants (R-502 and R-404A) cycles. The performance tests are conducted at the evaporation and condensation temperatures of $5^{\circ}C$ and $45^{\circ}C$, subcooling and superheating temperatures of $5^{\circ}C$, respectively. Performance comparisons between baseline and alternative refrigerants are conducted on the same cooling capacity. The system performance of newly proposed refrigerant mixtures show promising results.