• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.6
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• pp.753-762
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• 1998

A domestic refrigerator is composed of many components such as a compressor, evaporator, capillary tube, and the cabinet which plays a great role on the cycle performance, even if it is not the basic component part in the cycle. Recently, the restriction policy on the energy-saving and environmentally friendly refrigerator is reinforced in our nation as well as developed countries. Therefore, in this paper, cycle simulations and experiments were carried out ito understand the characteristics of the cycle performance using CFC 12, HFC 134a, and HC 600a and to know how changes in UA(overall heat transfer coefficients$\times$ heat transfer area) of evaporator, the position displacement of compressor, and the rpm of fan in the freezing room which has influence on the cycle performance. The result shows that the quantitative values of simulation and experiment are not coincident, but their trend is similar. When HFC 134a and HC 600a were used without the change of design in refrigerator used CFC 12, the performance of system in HC 600a is 30% lower, and the case of HFC 134a is 10% lower than that of CFC 12 on freezing temperature.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.7
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• pp.966-979
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• 1998

Thermodynamic and dynamic analysis has been conducted to investigate performance variations induced by substitution of alternative refrigerants, HFC134a or HC600a for CFC12 in hermetic reciprocating compressors. For the thermodynamic analysis, mass and energy conservation laws are applied to the cylinder volume and Helmholtz resonator modeling method is adopted to describe gas pulsations at suction and discharge system. The modeling of the dynamics of the compressor mechanism has been performed with lumped mass method to analyse the bearing loads and friction losses at each bearing. To verify the correctness of this analysis, results of the performance simulation have been compared to those of calorimetric measurrements of compressor operating with CFC12. Analysis of the various losses, noise and reliability as well as performance has been conducted to present the design guideline for the compressor development with alternative refrigerants. It is found that compressors with alternative refrigerants, HFC 134a or HC600a give better COPs than those with CFC12 under the same operating conditions and especially, compressors with HC600a show better reliability and noise characteristics also.

• Journal of the Korean Applied Science and Technology
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• v.14 no.2
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• pp.41-48
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• 1997

Separation of EPA and DHA from fish oil fatty acid ethyl ester (FAFE) by urea adductive crystallization method was carried out in the supercritical carbon dioxide (SC $CO_2$) as a solvent. Our results showed that SC $CO_2$ is a good candidate as a solvent in the urea adductive crystallization to separate FAFE by the number of unsaturated bonds. Compared to the separation process using methanol. SC $CO_2$ yielded better performance in the overall selectivity of EPA and DHA. The effect of process variables on separation of EPA and DHA was discussed in detailed. A hybrid technology of SC $CO_2$ fractionation and urea adductive crystallization with SC $CO_2$ was conformed as a viable process to separate and concentrate EPA and DHA from fish oil.

• Journal of the Korean Applied Science and Technology
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• v.14 no.2
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• pp.115-122
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• 1997

The field of printing use to pressurization ink using screen gassamer that is called screen printing. Existing cleaning solvent using screen printing are the organic solvents including aromatic compounds carried with poisonous and stench. Besides, cleaning method of current screen printing are for the most part mixed cleaning method of dipping and polish. Using 1,1,1-TCE, CFC-113 alternative system cleaning solvent be substituted for existing cleaning solvent against screen printing ink measured the cleaning efficiency according to gravimetric analysis method and property change of gassamer according to Image Analyzer. Also, Cleaning process system carry with excellent cleaning efficiency studied which was proposed new cleaning process including ultrasonic and vibration cleaning process be substituted for existing mixed cleaning method of dipping and polish.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.1
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• pp.151-165
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• 1996

Relation between condensate retention and heat transfer performance is studied for condensation of CFC-11 on horizontal integral-fin tubes. Eight tubes with trapezoidally shaped integral fin density from 738fpm to 1654fpm and 10, 30 grooves are tested. The liquid retention angles are measured by the height gauge, and each tube is tested under static(non-condensing) condition (CFC-11, water) and under dynamic(condensing) condition (CFC-11). The analytical model predicts the amount of liquid retention on a horizontal integral-fin tubes within＋10 percent over most of the data. Average retention angle increases as both surface tension-to-density ratio($\sigma/\rho$) and fin density(fpm) increase, The tube having a fin density of 1299~1654fpm has the best heat transfer performance. The amount of surface flooding must keep below of 40 percent for best heat transfer performance at condensation. The tube having low number of fin density must be used for fluids having high values of $\sigma/\rho$(water, (TEX)$NH_3$, ect.) and the tube having high number of fin density must be used for the fluid having low values of $\sigma/\rho$(R-11, R-22, etc.)

• Clean Technology
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• v.14 no.3
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• pp.184-192
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• 2008

Fluoride-type cleaning agents such as 2,2,2-trifluoroethanol (TFEA) and hydrofluoroethers (HFEs) do not destroy ozone in the stratosphere and have low global warming potential compared to hydrofluorocarbons(HFCs) and hydrochlorofluorocarbons (HCFCs). Especially, HFEs which have no flash point are paid attention as next generation type of cleaning agents for chlorofluorocarbons (CFCs) since they are safe in handling and have excellent penetration ability compared to hydrocarbon cleaning agents with low flash point. Here, the physical properties and cleaning abilities of fluoride-type cleaning agents such as TFEA, HFE-7100, HFE-7200, HFE-476mec, HFE-449mec-f, AE-3000 and AE-3100E and silicide-type cleaning agents such as trifluoroetoxytrimethylsilane (TFES) and hexamethyldisilazane (HMDS) were measured and compared with those of ozone destruction substances such as CFC-113 and 1,1,1-trichloroethane. They were also compared with toxic methylene chloride (MC) and isopropyl alcohol (IPA) which are now being used as an alternative cleaning agents. As a result, TFEA and HFEs had lower cleaning ability for removal of various soils compared to chloride-type cleaning agents, but they showed excellent cleaning ability fur fluoride-type soils. TFES and HMDS also showed excellent cleaning ability for silicide-type soils.

• Communications of the Korean Institute of Information Scientists and Engineers
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• v.14 no.4
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• pp.39-48
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• 1996

• Bulletin of Korea Environmental Preservation Association
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• v.19 no.7
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• pp.72-75
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• 1997

• 기계와재료
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• v.3 no.1 s.7
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• pp.16-19
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• 1991

• The Science & Technology
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• v.26 no.10 s.293
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• pp.18-23
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• 1993