• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.26 no.5
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• pp.396-404
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• 1997

• Journal of the Korean Mathematical Society
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• v.27 no.2
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• pp.185-192
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• 1990

• Bulletin of the Korean Chemical Society
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• v.17 no.7
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• pp.656-657
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• 1996

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.384.2-384.2
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• 2016

Recent publications reported the self-propelled jumping of coalescing dew droplets on superhydrophobic surfaces [1-2]. We further investigated the initial growth, coalescence, and removal by self-propelled ejection of nano and microscopic water droplets on the superhydrophobic surface of lotus leaves under condensing conditions. By using a high-speed digital camera mounted on an optical microscope, we have found: (1) sub-micrometer droplets form and grow on nanoscale waxy hairs; (2) growing droplets coalesce rapidly upon contact, but never jump off the surface unless the diameter of merged droplets exceeds ${\sim}15{\mu}m$; (3) the diameter and direction of jumping droplets are very narrowly distributed, centered at $20-30{\mu}m$ and ${\sim}20$ degrees from the surface normal, respectively. We present a rationale for these observations on the basis of: (a) the hierarchically rough surface structure on nano- and micro-scales; (b) its chemical composition; and (c) the balance among competing forces of cohesion (surface tension), adhesion and gravity.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2000.11a
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• pp.237-242
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• 2000

This study was carried out to optimize burner of the condensing gas boiler which can save energy by utilizing the latent heat of combustion gas and reduce pollutants emission. Three reasonable distances between burner and heat exchanger were decided through the experiments of model flat burner. The optimum burner geometry was determined from flame stability, pollutant emission characteristics and applicability to practical boiler system. The boiler designed by this research reaches turn-down ratio 5:1 in the domain of equivalence ratio 0.68∼0.85 and thermal efficiency of 98%. Emission of NOx and CO concentration was under 35ppm and 104ppm.

• Journal of the Korean Society of Industry Convergence
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• v.14 no.3
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• pp.113-119
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• 2011

This study analyzed facts affecting the performance of refrigeration systems after throttling actions, by changing the amount of refrigerant according to adjusting the opening of manual expansion valve to 80%, or 20% with vapor compressional refrigeration training equipment. At opening of 20%, the inlet and outlet temperature of compressor, subcooling and superheat, condenser heat, refrigeration effect, flash gas heat, coefficient of performance were higher, while at 80%, condensing pressure, evaporating pressure, compression work were higher, Thus, we could see changes in the amount of refrigerant affect the performance of the refrigeration system.

• Journal of the Korean Mathematical Society
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• v.35 no.4
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• pp.803-829
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• 1998

We give general fixed point theorems for compact multimaps in the "better" admissible class $B^{K}$ defined on admissible convex subsets (in the sense of Klee) of a topological vector space not necessarily locally convex. Those theorems are used to obtain results for $\Phi$-condensing maps. Our new theorems subsume more than seventy known or possible particular forms, and generalize them in terms of the involving spaces and the multimaps as well. Further topics closely related to our new theorems are discussed and some related problems are given in the last section.n.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.4
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• pp.492-498
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• 1999

Mass flow rates of R407C and R290 through capillary tubes were measured with various capillary tube geometries and flow conditions. For all refrigerants tested in the present study, mass flow rate through the capillary tube was strongly dependent on the condensing pressure, subcooling and capillary length and diameter. The flow rate of R407C was 5~10［%］ higher than that of R22 at the same condensing temperature and degree of subcooling, while flow rate for R290 was 40［%］ lower than that for R22. Based on experimental results, an empirical correlation was developed using Pi theorem to predict the mass flow rate through capillary tubes. The predicted flow rates using the model were consistent with the experimental data within ${\pm}$10[%］.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.2
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• pp.218-224
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• 2006

Experimental results for pressure gradient of HCs refrigerants R-290. R-600a. R-1270 and HCFC refrigerant R-22 during condensing inside horizontal double pipe heat exchangers are presented. The test sections which have the tube inner diameter of 10.98mm. and the tube inner diameter of 8mm are used for this investigation. Hydrocarbon refrigerants have higher pressure drop than R-22 in both test sections with the diameters of 12.70mm and 9.52mm. Pressure drop increased with the increase of the mass flux. These results form the investigation can be used in the design of heat transfer exchanger using hydrocarbons as the refrigerant for the air-conditioning systems

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.1
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• pp.25-32
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• 1999

This study was carried out to reduce NOx emissions from diesel engine and to investigate the variation of engine performance using the water injection. In this study the water was extracted from the exhaust gas and injected directly into the intake port with the inlet charge. The water condensing system operated as a closed system without any supplementary water supply. The experimental parameters such as the revolution the torque and the water injection rate are varied and the result from this experiment found the significant NOx reduction whereas the smoke emission increases as water/air ratio increases as the cases like the EGR. In spite of increasing the quantity of the water injection the engine output was slightly decreased and the specific fuel consumption was increased as was anticipated. Especially the system was founded to be effective on the reduction of the NOx emissions at the high load region relatively.