• Journal of the Korean Society of Combustion
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• v.7 no.1
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• pp.58-64
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• 2002

The bed combustion in an incinerator interacts with the gas flow region through heat and mass transfer. Combined bed combustion and gas flow simulations are performed to investigate this coupled interaction for various operating conditions and furnace configurations. Radiation onto the bed from the furnace is interrelated with the combustion characteristics in the bed, and is also affected by the flow pattern in the gas flow region. Since the contribution of gaseous emission to the total radiation is significant, an adequate flow pattern in a well-designed furnace shape would lead to an increased heat influx on the bed, especially in the early stage of the waste combustion. Advancing the initiation point of the waste combustion can also reduce the size of the lower gas temperature region above the bed, which can be achieved by controlling operating conditions such as the waste feeding rate, the bed height and the primary air flow distribution.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.71-73
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• 2012

With numerical simulations, this study investigated the combustion and heat transfer of three different coals under air- and oxy-fuel combustion in a 100 MWe boiler. The boiler is retrofitted to an opposed-firing type while maintain the original furnace shape of downshot firing. The boiler achieved good combustion in both combustion modes for three coals tested. However, the contribution of gasification reactions by $CO_2$ and $H_2O$ significantly increased due to the lack of gaseous mixing. This was different from a typical front-wall firing boiler, which showed larger contribution of char oxidation during air-coal combustion. The wall heat flux was lower in oxy-coal mode at a $O_2$ level of 27%, which has to be considered in further development of the process.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.610-617
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• 2020

In process installations, chemicals operate at high temperature and high pressure. Propylene is used as a basic raw material for manufacturing synthetic materials in the petrochemical industry; However, it is a flammable substance and explosive in the gaseous state. Thus, caution is needed when handling propylene. To prevent explosions, an inert gas, carbon dioxide, was used and the changes in the extent of explosion due to changes in pressure and oxygen concentration at 25 ℃, 100 ℃, and 200 ℃ were measured. At constant temperature, the increase in explosive pressure and the rates of the explosive pressure were observed to rise as the pressure was augmented. Moreover, as the oxygen concentration decreased, the maximum explosive pressure decreased. At 25 ℃ and oxygen concentration of 21%, as the pressure increased from 1.0 barg to 2.5 bar, the gas deflagration index (K_g) increased significantly from 4.71 barg·m/s to 18.83 barg·m/s.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.150-153
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• 1997

Langmuir-Blodgett(LB) technique is one of the ways of fabricating organic ultra-thin films. It is well known that It has the advantage to control the alignment and orientation of the molecules in the films. Metallo-phthalocyanines(MPcs) are sensitive to electron affinitive toxic gaseous molecules, such as NO$_2$, NO, SO$_2$. MPcs are thermal, optical, mechanical, chemical stable. Therefore, it is interesting to prepare phthalocyanine LB films containing copper as a chemical sensor for NO$_2$ and SO$_2$ gas and test their sensitivity to these toxic gases. In this study, thin films of Octa-dodecylosy copper-phthalocyanine were prepared by LB technique. $\pi$-A isotherm, transfer ratio, UV-VIS. spectroscopy of these films were investigated. Also current-voltage(I-V) characteristics of these was auto investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.146-149
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• 1997

It is well known that the metallo-phthalocyanines(MPcs) are sensitive to toxic gaseous molecules, such as NO$_2$, NO, SO$_2$. MPcs are thermally, optica1ly, mechanically and chemically stable. Therefore, it is interesting to prepare phthalocyanine LB films containing tin as a chemical sensor for NO$_2$ and SO$_2$ gas and test their sensitivity to these toxic gases. Frist, in this study, ultra thin films of Octa-dodecyloxy tin-phthalocyanine were prepared on various substrates by LB technique. Langmuir-Blodgett(LB) technique is one of the ways of fabricating organic thin films. It has the advantage to control the alignment and orientation of the molecules in the films. $\pi$-A isotherm and transfer ratio of tin-phthalocyanine derivative. UV-VIS. spectroscopy were investigated. Also intrinsic current-voltage(1-V) characteristics of these films was investigated.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.5 no.4
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• pp.249-256
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• 1993

Numerical method is applied to predict the time variation behavior of flammable mixture formation in a two dimensional enclosure from the beginning of gas leak. Additionally experimental method is used to consider qualitative aspects. Characteristics of flammable mixture formation such as distribution of flow and fuel mass fraction at various locations in the enclosure are determined for the following parameters: the various locations of leak at the bottom and aspect ratio of the enclosure. In the case of gas leak with small leak velocity from the bottom of enclosure gravitational force affects the formation of flammable mixture. Aspect ratio of the enclosure also affects the formation of flammable mixture. The volume of the region of recirculating flow is dominant factor affecting the formation mixture.

• Journal of environmental and Sanitary engineering
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• v.14 no.2
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• pp.113-119
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• 1999

In this study, the incineration of MEK and toluene was studied on a Pt supported alumina catalyst at temperature range from 200 to $350^{\circ}C$. An approach based on the Mars-van Krevelen rate model was used to explain the results. The object of this study was to study the kinetic behavior of the platinum catalyst for deep oxidation. The conversions of MEK and toluene were increased as the inlet concentration was decreased and the reaction temperature was increased. The maximum deep conversion of MEK and toluene were 91.81% and 55.69% at $350^{\circ}C$, respectively. The ${\kappa}_3$ constant increases with temperature faster than the ${\kappa}_1$ constant, that is, the surface concentration of ($VOCs{\cdots}O$) is higher than that of (O) at higher temperature according to the Mars-van Krevelen mechanism. Also the activation energy of toluene was larger than MEK for toluene is aromatic compound which have stronger bonding energy.Therefore, the catalytic incineration kinetics of MEK and toluene with Mars-van Krevelen mechanism could be used as the basic data for industrial processes.

• Food Science and Preservation
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• v.5 no.1
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• pp.73-80
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• 1998

Shelf-life of soybean curd prepared with ozone-treated soybeans investigated on pH, acidity, sour taste, slime formation during storage at 3$0^{\circ}C$. Total Plate counts of raw soybeans showed about log 7.0 CFU/g before ozone treatment. The sterilization efficiency of raw soybeans showed the most effective in 0.5ppm of aqueous ozone treatment at 4$^{\circ}C$ for 90 minutes. Raw soybeans were treated with ozone by different methods; (1) Ozone treatment for 90 + 90 minutes (first 3.5~5 hours and later 8.5~10 hours) of 10 hours during soaking in aqueous solutions at 4$^{\circ}C$ (OW). (2) Ozone treatment by exposure first to 30ppm of gaseous ozone for 90 minutes and then allied to OW method (GO+OW). The log reduction of raw soybeans treated by OW and GO+OW methods showed 3.72 and 4.15, respectively. Soybean curd prepared with OW and GO+OW-treated soybeans kept the shelf-life of 4 and 5.5 days at 3$0^{\circ}C$, respectively, but, that without ozone treatment spoiled at me day.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.4
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• pp.166-169
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• 2001

6H-SiC bulk crystals were grown by sublimation method with different conditions in term of gaseous pressures ad source temperatures. In order to optimize the growth rate, pressure at growth period and source and substrate temperatures were investigated as experimental variables. the results were compared with each other and finally the optimum growth conditions were discussed. Furthermore the relation of the growth steps and defects formation was evaluates in the point of reducing the micropipes. Subsequently the growth steps and defects formation was evaluated in the point of reducing the micropipes. Subsequently the growth steps were observed leading to the lower step height with the lower growth rate.

• Journal of Environmental Health Sciences
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• v.11 no.2
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• pp.1-16
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• 1985

There are a large number or chemical compounds that are present in a polluted atmosphere and that alone or in combination are important to consider for their potential effect on the respiratory system and impact on athletic performance. A general categorization or description of the level of pollution in terms of the concentration of one or more compounds or by type such as oxidizing compounds is inadequate and misleading. A useful initial categorization of pollutant compounds according to their mechanism of production, primary or secondary, is often made. For health effects, consideraiions of the physical state, gaseous or particulate, and the solublity and reactivity of the pollutant is also important. Pollutant compounds or substances that are emitted directly from a source and that undergo little or no chemical change in the atmosphere from source to receptor are termed primary pollutants.