• International Journal of Automotive Technology
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• v.2 no.1
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• pp.25-31
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• 2001

It is necessary to understand the combustion process and cycle-by-cycle variation in combustion to improve the engine stability and consequently to improve the fuel economy and exhaust emissions. The pressure related parameters instead of mass fraction burned were compared for the effect of initial combustion pressures on the following combustion and the analysis of cycle-by-cycle variation in combustion for two pen injected SI engines. The correlation between IMEP and pressures at referenced crank angles showed almost the same trends for equivalence ratios, but the different mixture preparations indicated different tendency. The dependency of IMEP on pressure at the referenced crank angles increases as the mixture becomes leaner for both engines. The mixture distribution in the combustion chamber was varied with the coolant temperature and intake valve deactivation due to the evaporation of fuel and air motion. The correlation between pressure related parameters were also compared for the coolant temperatures and air motion.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.8
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• pp.354-358
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• 2003

In this paper, insulations characteristics by temperature changes(＋50～-50[$^{\circ}C$]) of $SF_{6}$ gas in the experimental chamber were studied. From this result, at the low temperature, the breakdown voltage was increased with a drop of temperature and an increase of inner pressure in GIS. In addition the ability of insulation of liquid $SF_{6}$ was higher than that of the highly pressurized $SF_{6}$ gas. That is, with progress of low temperature, the main reason of breakdown was not liquefaction of $SF_{6}$ but rapid decrease of inner pressure. This study will come in greatly handy for the insulation design of GIS in a hard cold region

• Journal of ILASS-Korea
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• v.3 no.1
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• pp.10-18
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• 1998

To investigate the in-cylinder phenomena in a SI engine with 3 valves and pent-roof type combustion chamber, flow fields, fuel distributions, and flame propagations were measured in a single c!'tinder visualized engine. Flow fields were visualized by PTV system during the intake and compression process. Fuel distributions were measured by PLIF at the various engine conditions including the cold and hot engine conditions and the effect of air-shrouded injector on the fuel distribution was investigated also. In addition, flame propagation patterns were characterized.

• Food Science and Preservation
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• v.3 no.1
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• pp.55-60
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• 1996

To obtain the basic data on precooling effects for establishment the suitable postharvest handling technique or method of keeping high quality of vegetalble corn, the sweet, supersweet and waxy corn, (Danok #2, Cocktail #86 and Chalok #1), being mainly consumed as vegetables in Korea, were precooled with ice or vacuum cooling method immediately after harvest. The vacuum cooling was the most effective for the field heat removal of vegetable corn. It took only 30 min. at 4 to 5 torr of cold chamber pressure of vacuum precooler to lower the corn temperature from 30 to 2$^{\circ}C$. The ice cooling was also thought to be a useful precooling method with relatively short cooling time of 6 hrs. The vegetable corn treated with vacuum or ice cooling showed low and stable respiration rates of 25.5 to 43.5 CO2 mg/kg/hr. when stored at 0∼2$^{\circ}C$ while the samples stored at room temperature (20∼25$^{\circ}C$) without precooling were as high as 64.1 to 245 CO, mg/kg/hr.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.10
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• pp.925-931
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• 2000

Refrigerating ability of vapor compression refrigerator is decided by the harmonic work of it's components such as compressor, condenser, evaporator, expansion device, and so on. In this study, choosing refrigerant injectors as a new one of expansion device, temperature change of the cold room, ice freezing ability, and power consumption on flowrate of injector and refrigerant charging condition are evaluated experimentally. As the results of this study, it is verified that the spray injection type refrigeration system has some merits according to the flowrate and spray pattern of injector and charging quantum of refrigerant. And there are some design factors such as spray pattern and shape of spray chamber to utilize and fabricate this refrigerant injection type refrigerator.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.597-600
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• 2010

Cold flow injection test was conducted to investigate the characteristics of cryogenic liquid nitrogen jet at sub to supercritical condition. Single jet injector element was installed in high pressure chamber to investigate the effect of ambient pressure around the jet, injector geometry and flow conditions. Experimental results showed obvious differences between jet characteristics under subcritical and supercritical condition. Effect of injector inlet shape also was investigated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.618-619
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• 2010

Thermal transpiration device(Knudsen pump) having no moving parts can self-pump the gaseous propellant by temperature gradient only (cold to hot). We designed, fabricated the Knudsen pump and analyzed pressure gradient efficiency of membrane according to Knudsen number under vacuum condition. In this paper, we measured presented pumping efficiency of Knudsen pump according to Hanji membrane.

• Journal of the Korean Institute of Landscape Architecture
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• v.21 no.3
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• pp.99-104
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• 1993

The objectives of this study were investigation of the sutiable propagation method by softwood cuttings of female Ilex serrata, the comparison of sex determination of Ilex serrata after seeding and the fruiting percentage of the Ilex serrata male and female. The results obtained were as follows. 85 percentage of the seed were germinated with three months cold stratification. 35 percentage of female plant were observed after seeding. Cuttings should be rooted on late June using a quick dipping of 1,000ppm IBA solution. The rooting rate of the softwood cuttings treated IBA 1,000pm on June 22 in a closed moist chamber with 50% shade screen was 72.2 percentage. The suitable planting of male and female of Ilex serrata was male one versus female thirteen in a distance of 50 meter.

• Journal of the Korean Society of Clothing and Textiles
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• v.15 no.4 s.40
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• pp.447-451
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• 1991

Effects of insulation after exposure of the extremities on the temperature regulation in clothed men were studied. Experiment was carried out with six males in a climatic chamber fixed at $10^{\circ}C$, $55\%$ R.H. treated with Type A (face only was exposed) and Type B (face and half of the extremities were exposed). Mean skin temperature fell greater in Type B due to intense vasoconstriction than in Type A. Rectal temperature rose a little in Type B and resumed in Type A without any significant differences in metabolism between two types of clothing. These findings suggest that Type B is more effective in physiological defense to the cold stimuli than Type A at least at $10^{\circ}C$.

• Journal of Surface Science and Engineering
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• v.23 no.2
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• pp.1-10
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• 1990

Metal-Organic Vapor Phase Epitaxy (MOVPE) is an epitaxial process utilizaing ane or more of organometallice as reactnte to grow compound semicond semiconductror layers. MOVPE is basically a cold wall process in which reactants are delivered without reacting with each other to the heated substrate where reactants are thermally decomposed to from compound semiconductors through chemical reaction. Since reactants are delivered as gas phase and the formation of the single crystal compunds depends on the thermal decomposition of the reactants, details of MOVPE relies on the hydrodynamics and pyroltsis and chemical reation of reactants inside on reaction chamber. It has been demonstrated that MOVPE is capable of growing virtually all of the III-V, II-VI and IV-VI compound semiconductrs, fabricating ultrathin epilayers, for ming abrupt hetrointerfaces with monolayer transition width, and is suitable for multi-wafer operation yilding a high throghtput. Overiew of reactror componts and layer, characteristics, and status of MOVPE are discussed.