• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.27-36
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• 2018

A significant amount of studies were performed on evaporation heat transfer and pressure drop in microfin tubes. Most studies, however, focused on the refrigerants used in air-conditioners or heat pumps, and very limited information is available on R-404A, which is used in low temperature refrigeration. In this study, the evaporation heat transfer and pressure drop characteristics of R-404A in a 9.5 mm O.D. microfin tube were investigated for the mass flux range from $80kg/m^2s$ and $200kg/m^2s$. A smooth tube of the same outer dimeter was also tested for comparison. The results showed that the heat transfer enhancement ratio of the microfin tube increased with increasing mass flux and the heat flux decreased. The relative contribution of the convective heat transfer and the heat flux on total heat transfer was attributed to the observed trend. The pressure drops of the microfin tube were slightly (maximum 28%) larger than those of the smooth tube. Existing correlations do not adequately predict the measured heat transfer coefficients of pressure drops, probably due to the test range of the present study, which is outside of the existing correlations.

• The Korean Journal of Pesticide Science
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• v.18 no.3
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• pp.191-195
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• 2014

Occurrence of soybean pod gall midge (SPGM), Asphondylia yushimai, and soybean pod damage caused by SPGM, and its control efficacy treated with ethofenprox 20EC were first observed at Miryang from 2006 to 2008 in Korea. The typical damage symptoms in soybean pod caused by SPGM were brownish coloration and malformation. By beating method occurrence of SPGM was observed from beginning bloom of soybean and its collected population increased with season until middle September. Soybean pod damage caused by SPGM was heaviest at seeding date of 10th May, followed by 11th June and 26th May. Control efficacy against SPGM sprayed with one time application of ethofenprox 20EC at different spray time in soybean reproductive stage was highest with 92.9% at R2.5, followed by 87.9% at R2 and 83.6% at R3, and was low from about 19 to 66% at other spray time. Accordingly, the most effective spray time of insecticide for control of SPGM in soybean field was found to be R2.5 which is between R2 and R3.

• Journal of the Korean Society of Costume
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• v.38
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• pp.323-336
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• 1998

The purpose of this study was to classify the contents of self-image of college men and to investigate how clothing behavior was influenced by self-image, age, major, and the expenses of clothing. Samples were 342 male students of univer-sity in Seoul. Results of this study were following : 1. Four factors of self-image derived by factor analysis : F. 1‘mature-unmatured’;F. 2‘characteristic-ordinary’; F. 3‘conservative-open’; F. 4‘dominant-submissive’.2. 5 variables of clothing behavior were influenced by real self-image. Fashion was influenced by characteristic, open, dominant image, and the expenses of clothing. The ex-planatory power of the 4 variables was 29.3%. Aesthetics was influenced by characteristic, submissive, conservative image, the expenses of clothing, and age(R2=28.7%). Modesty was influenced by conservative and ordinary im-age(R2=6.5%). Coformity was influenced by ordinary image and the expenses of clothing (R2=5.7%). Comfort was influenced by dominant image and age(R2=5.3%). 3. 5 variables of clothing behavior were influenced by ideal self-image. Fashion was influenced by unmatured, characteristic, sub-missive image, and the expenses of clothing (R2=28.9%). Aesthetics was influenced by characteristic image, the expenses of clothing, and age(R2=23.5%). Modesty was influenced by conservative, mature, and ordinary image (R2=8.3%). Coformity was influenced by ordinary image(R2=1.9%). Comfort was influenced by mature image and age(R2=5.6%). The findings indicated that self-image had a significant effect on fashion and aesthetics, and characteristic image and conservative image were important variables that affected clothing behavior of college men.

• International Journal of Air-Conditioning and Refrigeration
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• v.9 no.2
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• pp.85-93
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• 2001

The present study experimentally investigated the effect of refrigeration oil on the condensation heat transfer for R-22 and R-407C in a microfin tube with a U-bend. Mineral oil and POE oil were used for R-22 and R-407C respectively. Experimental parameters were an oil concentration from 0 to 5%, a mass flux from 100 to 400 $kg/m^2s$ and an inlet quality from 0.5 to 0.9. The enhancement factors for both R-22 and R-407C refrigerants at the first straight section decreased continuously as the oil concentration increased. The decreased rapidly as the mass flux decreased and the inlet quality increased. The heat transfer coefficients in the U-bend showed the maximum at the 90$^{\circ}$position. the heat transfer coefficients at the second straight section within the dimensionless length of 48 were larger by a maximum of 33% than the average heat transfer coefficient at the first straight section.

• Solar Energy
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• v.15 no.3
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• pp.75-90
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• 1995

This paper is concerned about alternative refrigerants for HCFC22 used in room air conditioners and heat pumps. Computer simulation of residential air conditioners using refrigerant mixtures is carried out. Following refrigerants are selected as the pure refrigerants constituting the mixtures studied: R32, R124, R125, R134, R134a, R143a and R152a. Simulation results are presented fur the following mixtures: R32/R134a, R32/R152a, R32/R134, R32/R124, R143a/R134a, R143a/R152a, R143a/R124, R125/R134a, R125/R152a, R125/R124, R32/R152a/R134a, R32/R152a/R134, R32/R152a/R124. The best fluid is found to be the ternary mixture of R32/R152a/R124. For that mixture, the coefficient of performance(COP) and volumetric capacity for refrigeration(VCR) are 13.7% larger and 23% smaller than the respective values for HCFC22. R32/R124 mixture is the best binary fluid pair whose COP and VCR are 13.4% larger and 9.6% smaller than those for HCFC22.

• Proceedings of the Korean Ceranic Society Conference
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• 2004.04b
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• pp.47.4-47.4
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• 2004

• Proceedings of the Materials Research Society of Korea Conference
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• 1996.11a
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• pp.55-55
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• 1996

• 한국전기화학회:학술대회논문집
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• 1999.10a
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• pp.9-9
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• 1999

• Bio news
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• no.5
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• pp.9-9
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• 2004

• Science & Technology Policy
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• v.7 no.9 s.102
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• pp.6-9
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• 1997