• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.2
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• pp.229-237
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• 1996

The superconducting phase, $YBa_{2}Cu_{3}O_{x}$ (YBCO), was in-situ deposited on the single crystal MgO substrates, using an aerosol decomposition process in a cold plasma reactor. The solubility and decomposition temperature of the chemical precursors, and the vapor pressures of the solvents, were determined to be the factors crucial to achieving a stoichiometric, crystalline YBCO phase. The deposition parameters for the YBCO phase were 0.3 to 2.7 kPa for the oxygen partial pressure and $800^{\circ}C$ to $940^{\circ}C$ for the substrate temperature. The optimum deposition conditions for the YBCO phase were observed along the CuO decomposition line.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.147-147
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• 2010

PTC Thermistors specimens were fabricated by added $MnO_2$ as donors, and $Nb_2O_5$ as acceptors and sintered $1250^{\circ}C$/2hrs. Average grain size decreased with increased in added $MnO_2$, and increased with added in $Nb_2O_5$. But, appeared liquid phase as $Bi_2O_3$ and $TiO_2$, affect to grain growth. XRD result, peak strength waslowed then crystallization not well, but, secondary phase were not showed all specimens. All specimens resistance were so high, about $40M{\Omega}$ over, couldn't measured to those resistance and doesn't appear PTCR effect.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.4
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• pp.614-621
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• 2002

This study was performed to investigate the behavior of vapor phase of fuel mixtures with different piston bowl shapes(F, B and R-type) in a optically accessible engine. The images of liquid and vapor phases were captured in the motoring engine using exciplex fluorescence method. Fuel was injected into atmospheric nitrogen to prevent quenching phenomenon by oxygen. Injection pressure was 5.1MPa. Two dimensional spray fluorescence image of vapor phase was acquired to analyze spray behaviors and fuel distribution inside of cylinder. Four injection timings were set at BTDC 90$^{\circ}$, 80$^{\circ}$, 70$^{\circ}$, and 60$^{\circ}$. With a fuel injection timing of BTDC 90$^{\circ}$, fuel-rich mixture level in the center region was highest in a B-type piston. With a fuel injection timing of BTDC 60$^{\circ}$, R-type piston was best. R-type piston shape was suitable under enhanced swirl ratio and late injection condition and B-type piston shape was right in a weak swirl ratio. It was found that the piston bowl shape affected the mixture stratification inside of cylinder.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.5
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• pp.1735-1742
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• 1996

An entrained flow gasifier simulating the cold mode was tested to estimate its performance for coal gasification and flow characteristics with a developed high speed impinging jet nozzle. The burner was designed for high temperature and high pressure(HTHP) conditions, especially for IGCC(Integrated Coal Gasification Combined Cycle). In order to get proper size of droplets for high viscous liquid such as coal slurry, atomization was achieved by impacting slurry with high speed (over 150m/sec) secondary gas (oxygen/or air)/ Formed water droplets were ranged between 100.mu.m to 20.mu.m in their sizes. The flow characteristics in the gasifier was well understood in mixing between fuel and oxidizer. Both external and internal recirculation zones were closely investigated through experimentation with visualization and numerical solutions from FLUENT CODE.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.915-920
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• 2001

This study was performed to investigate the behavior of vapor phase of fuel mixtures with different piston bowl shapes(F, B, and R-type) in a optically accessible engine. The images of liquid and vapor phases were captured in the motoring engine using exciplex fluorescence method. Fuel was injected into atmospheric nitrogen to prevent quenching phenomenon by oxygen. Injection pressure is 5.1MPa. Two dimensional spray fluorescence image of vapor phases was acquired to analyze spray behaviors and fuel distribution inside of cylinder. Four injection timings were set at BTDC $90^{\circ},\;80^{\circ},\;70^{\circ},\;and\;60^{\circ}$. With a fuel injection timing of BTDC $90^{\circ}$, fuel-rich mixture level in the center region was highest in a B-type piston. With a fuel injection timing of BTDC $60^{\circ}$, R-type piston was best. R-type piston shape was suitable under enhanced swirl ratio and late injection condition and B-type piston shape was right in a weak swirl ratio. It was found that the piston bowl shape affected the mixture stratification inside of cylinder.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.4
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• pp.614-623
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• 2015

This study aims to estimate the Green-House-Gas emissions from domestic farmed flounder in the southern sea and Jeju-Do, where is mainly produced, by the assessment of energy consumptions and GHG emissions from domestic fish farms for establishing reduce standards of greenhouse gas from a sustainable perspective. It needs to analyze such GHG emission components as feed, electricity, fuel, fixed capital, fish respiration, and liquid oxygen in two locations by 4 stage running water type farm size of small, small and medium, large and medium, large scale. The result showed that the mean GHG emissions were $36.83kg{\cdot}CO_2/year$ in the southern sea and $24.33kg{\cdot}CO_2/year$ in Jeju-Do, respectively, in the stage of production per fish 1kg at 2 locations and farm size from domestic farmed flounders, and it will give to be useful for policy, planning, and regulation of aquaculture development with establishing GHG reduction standards.

• Proceedings of the Membrane Society of Korea Conference
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• 2002.04a
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• pp.23-46
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• 2002

The cryogenic, pressure swing adsorption and membrane methods have been used to separate air into nitrogen and oxygen. The air separation membrane is made of the polymers, of which manufacturing process is complicate and it causes a little high production cost. Polymer membrane has temperature limit in usage and low durability even at moderate temperature. Therefore, inorganic membranes have been studied for years. As formation of unit alumino-silicate membrane, unit cells of membrane were made with a few coating methods. In this study the dipping of substrate into sols, application of vacuum to the opposite side of substrate with coating and rotating of the substrate in the sols were found as good coating memthods to make a uniform coating and to control the thickness of membrane. The membrane coats were examined by SEM and XRD. The sample ESZl-1 was compared with those of samples that prepared by another method. The present developed coating methods could be applied to the various types of zeolite membrane formation, that is A- X-, Y- ZSM- and MCM-types of membranes. Also these membrane forming methods could be applied to formation of catalyst absorbed zeolite membrane, of which zeolite absorb the catalytic metals. The product obtained from these coating methods could be applied to the industrial gas and liquid phase catalytic reaction and separation processes.

• Journal of ILASS-Korea
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• v.21 no.1
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• pp.29-36
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• 2016

The effect of high ambient temperature and pressure conditions on the combustion performance of n-butanol, n-heptane and its mixing fuel (BH 20) were studied in this work. To reveal this, the closed homogeneous reactor model applied and 1000-1200 K of the initial temperature, 20-30 atm of initial pressure and 1.0 of equivalence ratio were set to numerical analysis. It was found that the results of combustion temperature was increased and the ignition delay was decreased when the ambient conditions were elevated since the combustion reactivity increased at the high ambient conditions. On the contrary, under the low combustion temperature condition, the combustion pressure was more influenced by the ambient temperature in the same ambient conditions. In addition, the total mass and the mass density of tested fuels were influenced by the ambient pressure and temperature. Also, soot generation of mixing fuel was decreased than n-heptane fuel due to the oxygen content of n-butanol fuel.

• Journal of ILASS-Korea
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• v.14 no.2
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• pp.49-58
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• 2009

Non-edible vegetable oils instead of edible vegetable oils as a substitute for diesel fuel are getting a renewed attention because of global reduction of green house gases and concerns for long-term food and energy security. Out of various non-edible vegetable oils, karanja, mahua, linseed, rubber seed and cotton seed oils are selected in this study. A brief review of recent works related to the application of the above five vegetable oils and its derivatives in CI engines is presented. The production technologies of biodiesel based on non-edible vegetable oils are introduced. Problems in vegetable oil or biodiesel fuelled CI engine are included. In addition, future works related to spray characteristics of non-edible vegetable oil or biodiesel from it are discussed. The biodiesel fuel, irrespective of the feedstock used, results in a decrease in the emission of hydrocardon (HC), carbon monoxide (CO), particulate matter (PM) and sulphur dioxide ($SO_2$). It is also said to be carbon neutral as it contributes no net carbon dioxide to the atmosphere. Only oxides of nitrogen (NOx) are reported to increase which is due to oxygen content in the biodiesel fuel. The systematic assessment of spray char-acteristics of neat vegetable oils and its blends, neat biodiesel and its blends f3r use as diesel engine fuels is required.

• Microbiology and Biotechnology Letters
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• v.27 no.2
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• pp.118-123
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• 1999

A bacterial strain, designated T116, degrading terephthalic acid (TPA) was isolated from the soil around Taegu industrial area into which dye works wastewater flow. The isolate was identified as pseudomonas sp. based on its morphological and physiological characteristics. Degradation of TPA by the strain T116 was confirmed with UV scanning and HPLC. About 90% and 98% of TPA were degraded after 36 and 60 hours, respectively, during the culture in a liquid medium containing 0.1% TPA. Addition of KH2PO4 at a final concentration of 100ppm enhanced the chemical oxygen demand (COD) removal rate about 50% from dye works wastewater by Pseudomonas sp. T116. Optimum pH and temperature for COD reduction from wastewater were 7.0 and 3$0^{\circ}C$, respectively. The bacterium was applied to the continuous culture for the treatment of dye works wastewater whose TPA concentration and CODMn were 2,200ppm and 1,620ppm, respectively. It was observed that 90-95% of COD was eliminated after 4 days culture in the continuous culture with a retention time of 37 or 47 hours.