• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.1
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• pp.73-79
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• 2010

Propellant tank pressurizing gas injector is used in the pressurization system of liquid propellant rocket to reduce incoming gas velocity and distribute the gas in the tank. Temperature distribution in the propellant tank ullage is varied according to the gas injector shape, and it has influence on the required pressurant gas and thermal phenomena in the tank. In this paper, diffuser type gas injector was studied to make the ullage have stratified temperature distribution. Injected gas flow at the outlet of prototype diffuser was visulized using particle image velocimetry method and it was compared with the results of calculation. Calculation was well agreed with measurement and was used as an inlet condition of propellant tank ullage calculation.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.173.1-173.1
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• 2011

The high fuel flexibility of gas turbine power system has boosted their use in a wide variety of applications. Recently, the demand for biogas generated from the digestion of organic wastes and sewage waste water as a fuel for gas turbines has increased. We investigated the performance of high pressure biogas compression system and operating conditions for supplying biogas. The total flow per minute of biogas from food waste water digestion tank is $54Nm^3$. The main type of biogas compression system is the reciprocating system and screw type system. The target of biogas mechanical data is the as belows; inlet pressure 0.045bar, supplying biogas temperature is $30{\sim}60^{\circ}C$, and final pressure is above the 25 bar. Also, inlet conditions of biogas consist of CH4 48.5%~83%, $H_2S$ Max. 500ppm, $NH_3$ Max. 1,500ppm and Siloxane 2.7~4.6ppm. The boosting Blower system raises a pressure from 0.045bar to 1bar before main compressor. The main system lay out of reciprocating consisits of compressor driver, filter, cooling system, blowdown vessel, control system and ESD(Emergency Shut Down) system. And an enclosure package needs to be installed for reducing noise up to 75dB. The system driver is the electronic motor of explosion proof type. Forthe compressor system reliable operation, the cleaning system something like particulate filter needs to be set up in the inlet of compressor and Coalescing Filter in the outlet of compressor. Particulate Filter has to be removed above $10{\mu}m$ size of the particles in biogas. The coalescing filter(Micofine Borosilicate Glass Fibers Filter treated phenol acid) also removes moisture and oil of above $0.3{\mu}m$ to be involved in high pressure biogas up to 90%~98%.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.6
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• pp.554-559
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• 1993

This experiment was carried out at Chuncheon substation, Crop Experiment Station to investigate the effect of cold water irrigation on the growth and grain yield of rice in 1990. Irrigation of cold water (17$^{\circ}C$) delayed 10 to 19 days of heading, and reduced about 17 to 31% of plant height in terms of culm and panicle length. Number of panicle per plant was decreased and / or increased by cold water irrigation. Cold water irrigation reduced spikelet number per panicle and percent of filled grain. Grain yield was increased but, straw weight was decreased according to water temperature gradient from inlet to outlet. There was varietal differences in head rice recovery by cold water treatment. In general the dark brown and / or black colored kernel increased at cold water inlet but decreased percent of green kernel. Alkali digestible value increased and amylose content decreased at cold water inlet.

• Journal of the Korean Electrochemical Society
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• v.8 no.4
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• pp.155-161
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• 2005

In this paper, commercial CFD program FLUENT v5.3 is used for simulation of MCFC stack. Besides using conservation equations included in FLUENT by default, mass change, mole fraction change and heat added or removed due to electrochemical reactions and water gas shift reaction are considered by adding several equations using user defined function. The stacks calculated are 6 and 25 kW class coflow stack which are composed of 20 and 40 unit cells respectively. Simulation results showed that pressure drop took place in the direction of gas flow, and the pressure drop of cathode side is more larger than that of anode side. And the velocity of cathode gas decreased along with the gas flow direction, but the velocity of anode gas increased because of the mass and volume changes by the chemical reactions in each electrodes. Simulated temperature profile of the stack tended to increase along with the gas flow direction and it showed similar results with the experimental data. Water gas shift reaction was endothermic at the gas inlet side but it was exothermic at the outlet side of electrode respectively. Therefore water gas shift reaction played a role in increasing temperature difference between inlet and outlet side of stack. This results suggests that the simulation of large scale commercial stacks need to consider water gas shift reaction.

• Journal of Mushroom
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• v.15 no.1
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• pp.14-20
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• 2017

The oyster mushroom cultivation house typically has multiple layers of growing shelves that cause the disturbance of air circulation inside the mushroom house. Due to this instability in the internal environment, growth distinction occurs according to the area of the growing shelves. It is known that minimal air circulation around the mushroom cap facilitates the metabolism of mushrooms and improves their quality. For the purpose of this study, a CFD analysis FLUENT R16 has been carried out to improve the internal environment uniformity of the oyster mushroom cultivation house. It is found that installing a section of the working passage towards the ceiling is to maintain the internal environment uniformity of the oyster mushroom cultivation house. When all the environment control equipment - including a unit cooler, an inlet fan, an outlet fan, an air circulation fan, and a humidifier - were operated simultaneously, the reported Root Mean Square (RMS) valuation the growing shelves were as follows: velocity 23.86%, temperature 6.08%, and humidity 2.72%. However, when only a unit cooler and an air circulation fan operated, improved RMS values on the growing shelves were reported as follows: velocity 23.54%, temperature 0.51%, and humidity 0.41%. Therefore, in order to maintain the internal environment uniformity of the mushroom cultivation house, it is essential to reduce the overall operating time of the inlet fan, outlet fan, and humidifier, while simultaneously appropriately manage the internal environment by using a unit cooler and an air circulation fan.

• Korean Journal of Food Science and Technology
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• v.42 no.1
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• pp.39-44
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• 2010

The process of the preparation of branched-chain amino acid (BCAA)-enriched hydrolysates from corn gluten was optimized through the parameters of pre-treatment (heating and cellulosic hydrolysis), hydrolysis method (acid, protease, and microbe plus protease), concentration, and spray drying condition. The protein yield of corn gluten was increased by heating and cellulase treatments. Among three different hydrolysis methods, the combined use of microbes and protease was the most effective in terms of free amino acid (FAA) and BCAA content of the corn gluten hydrolysates. In addition, the FAA and BCAA content in the hydrolysates prepared by microbial and enzymatic combined treatment were improved by a concentration process. Spray drying conditions for the preparation of the powder from the hydrolyzed reactant were an inlet temperature of $185^{\circ}C$, outlet temperature of $80^{\circ}C$, and the use of maltodextrin as an anticaking agent. Thus, this study established an economical process for preparation of value-added hydrolysates of excellent productivity and quality, in terms of high BCAA content and product stability.

• Korean Journal of Plant Resources
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• v.19 no.4
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• pp.497-508
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• 2006

This study was conducted to obtain the basic information on rice cold damage and relationship to be connected with cold tolerance. The 20 rice varieties were screened to cold tolerance under low water temperature condition. The water gradient were controlled to $17^{\circ}C$ at the inlet and $21^{\circ}C$ at outlet of screening field. In the relationship between cold water irrigation and growth of rice varieties, effect on medium maturing cultivars were higher than early maturing cultivars. In relationship of shorting of culm length and panicle exsertion, culm length and panicle exsertion showed positive correlation. Yield of cultivars and culm length and percent of fertile grain showed positive correlation. However, heading date presented negative correlation. In the early maturing cultivars, except 'Kumobyeo', all cultivars range of discoloration value (1-3) was resistant. In the medium maturing cultivars, 'Donghaebyeo' was resistant in both the seedling stage whereas 'Hwajinbyeo' was resistant only in tiller stage. Cold water irrigation reduced spikelet number per panicle and percent of filled grain. Unhulled rice yield was increased according to water temperature gradient from inlet to outlet. There was varietal differences in head rice recovery by cold water treatment.

• Journal of the Korean Solar Energy Society
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• v.26 no.4
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• pp.9-16
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• 2006

Geothermal-energy has been getting popular as a natural energy source for green buildings these days. Public building with gross area more than $3000m^2$, planned after March, 2005, should spend about 5% of total building cost for equipment run by natural energy source (e.g. geothermal, solar heat, solar power, etc) according to renewable energy promotion law in Korea. As a result geothermal-energy using heat pump system is emerging as a effective alternative for realistic and economic plan although design guidelines and construction code for the system is in progress and technical data is far from sufficient. The quantitative analysis on the performance of geothermal-energy using heat pump system is insufficient for appropriate design of it. In this paper, cooling performance of geothermal-energy using heat pump system of residential and retail etc. mixed-use building has been analyzed on the basis of temperature comparison between inlet and outlet of heat exchangers of the operating system. Additionally, dry-bulb temperature and relative humidity have been measured and analyzed together as an index of indoor thermal environment.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.1980-1985
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• 2007

The purpose of this study is to investigate the performance of an autocascade refrigeration system using the refrigerant mixtures of R-134a(64${\sim}$72wt%), R-23(20${\sim}$25wt%) and R-14(8${\sim}$12wt%) as working fluids by experiment. The experimental apparatus consisted of a autocascade system with a compressor, condenser, evaporator, gas-liquid separator and cascade condenser, etc. Two main causes to this failure were considered as follows. First, the pressure ratio in the compressor was extremely increased at the beginning of the experiment. Second, the outlet temperature in compressor was higher than its limited temperature. For a stable operation of the compressor, a portion of the mixed refrigerant was by-passed at the inlet of the heat exchanger and transferred directly to the suction of the compressor in the modified system. The experimental parameters were changed weight of R-134a(1800g, 2800g), R-23(700, 800, 900g) and R-14(300, 400, 500g). The results showed that the best performance in case of R-134a of 2800g, R-23 of 900g and R-14 of 500g.

• Journal of the Korean Society of Combustion
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• v.22 no.2
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• pp.36-41
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• 2017

Aero gas turbine engines must demonstrate their ability to be ignited on ground conditions or relighted in flight. The electric spark ignition is usually used in current aero gas turbine engines. Experiments on ignition characteristics relating to spark igniter penetration depth under atmospheric pressure and temperature conditions were conducted on the model combustor which is scaled in 1/18. Exciter was operated during 2 seconds, and successful ignition phenomena were confirmed by the pressure rising sharply in combustor. In addition, instantaneous ignition images were captured by a high-speed camera. It showed kernel propagation and successful ignition events in the sector model combustor. Ignition test results showed that ignition limit with increase in penetration depth of the igniter plug was wider. When the penetration depth of the igniter plug increased under the same fuel injection pressure condition, successful ignition events were obtained in higher differential pressure conditions between inlet and outlet of the combustor. The results demonstrate that the ratio of the combustible mixture, which is exposed to the high temperature environment around the igniter plug tip, increases. Thereby affect the combustor ignition performance.