• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.406-409
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• 1999

Experimental Investigations were carried out to remove NOx, SOx simultaneously from simulated flue gas[NO(0.02%)-SO$_2$(0.08%)-$CO_2$-Air-$N_2$] by using a plasma chemical reaction. Ammonia gas(14.81%) balanced by argon was diluted by all and was Introduced to mall simulated flue gas duct through NH$_3$ Injection system which is in downstream of reactor. The NH$_3$ molecular ratio(MR) was determined based on (NH3) to [NO+S0$_2$]. MR is 1, 1.5, 2.5. The NOx removal rate significantly increased with increasing NaOH bubble quantity. The SO$_2$ removal rate was not significantly effected by applied voltage, however it fairly Increased with increasing NH$_3$ molecule ratio. By-product aerosol particle was observed by XRD(X-ray diffraction) after sampling, The NOx, SOx removal rates, when H2O vapour bubbled by dry all was injected to plasma reactor, were better than those of other cases. When aqueous NaOH solution(20%) bubbled by 2.5( ι /min) of $N_2$ and 0.5 ( ι /min) NH$_3$(MR=1.5) were injected to simulated flue gas, The NOx. SOx removal rate was 95 ~ 100[%]

• Journal of the Korea Academia-Industrial cooperation Society
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• v.3 no.2
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• pp.115-119
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• 2002

This study was performed to improve mechanical properties of rotor and bushing materials. SACD and SKD11 steels as rotor and bushing materials were investigated. Gas nitriding and TiN coating were carried out on SACM and SKD11 steels. TiN coating was deposited on SKD11 steel by reactive sputtering process. This coated layer was picked off during the operation because of insufficient adhesion. Gas nitriding was carried out on SACM and SKD11 steels in an ammonia atmosphere at 51$0^{\circ}C$ for 72 hrs. These gas nitrided parts showed good mechanical properties. SKD11 steels were heat-treated to obtain optimum carbide size and distribution. As a results, the hardness increased.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.7
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• pp.611-619
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• 2010

The paper deals with the proper design of GGH(gas-gas heater) panel elements of desulfurization equipments in a thermoelectric power plant. When fossil fuels such as coal, petroleum et cetera are burnt to ashes, sulfur oxide compounds are produced, and calcareous sludges are deposited at GGH panel elements. In this case, operation of a power plant equipments is interrupted, and a tremendous economic loss comes into existence. One of the purposes of the paper is to find flow velocity distributions and regions of depositions when calcareous sludges pile up on the GGH panel elements through the fluid analysis. In the fluid analysis, flow velocity and position distributions of particles between GGH panel elements are demonstrated according to time variation for ammonia and calcium hydroxide particles.

• Journal of Sensor Science and Technology
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• v.28 no.5
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• pp.271-276
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• 2019

Pure and 0.5, 1, 2, 5, and 10 at% of Mo-doped $Co_3O_4$ yolk-shell spheres were synthesized by ultrasonic spray pyrolysis of droplets containing Co nitrate, ammonium molybdate, and sucrose and their gas sensing characteristics to 5 ppm trimethylamine (TMA), ethanol, p-xylene, toluene, ammonia, carbon monoxide, and benzene were measured at $225-325^{\circ}C$. The sensor using pure $Co_3O_4$ yolk-shell spheres showed the highest response to p-xylene and very low response to TMA at $250^{\circ}C$, while the doping of Mo into $Co_3O_4$ tended to increase the overall responses of gas sensors. In particular, the sensor using 5 at% Mo-doped $Co_3O_4$ yolk-shell spheres exhibited the high response to TMA with low cross-responses to other interfering gases. The high response and selectivity of Mo-doped $Co_3O_4$ yolk-shell spheres to TMA are attributed to the electronic sensitization by higher valent Mo doping and acid-base interaction between TMA and Mo components.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.3
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• pp.330-336
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• 2005

The ozone injection method was proposed to improve the catalytic process for the removal of nitrogen oxides ($NO_x$). Nitric oxide (NO) in the exhaust gas was first oxidized to nitrogen dioxide ($NO_2$) by ozone produced by dielectric barrier discharge, and then the exhaust gas containing the mixture of NO and $NO_2$ was directed to the catalytic reactor where both NO and $NO_2$ were reduced to $N_2$ in the presence of ammonia as the reducing agent. A commercially available $V_2O_5-WO_3/TiO_2$ catalyst was used as the catalytic reactor. The $NO_2$ content in the mixture of NO and $NO_2$ was changed by the amount of ozone added the exhaust gas. The effect of reaction temperature, initial $NO_x$ concentration, feed gas flow rate, and ammonia concentration on the removal of $NO_x$ at various $NO_2$ contents was examined and discussed. The increase in the content of $NO_2$ by the ozone injection remarkably improved the performance of the catalytic reactor, especially at low temperatures. The present ozone injection method appears to be promising for the improvement of the catalytic reduction of $NO_x$.

• Journal of the Korean Wood Science and Technology
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• v.33 no.3 s.131
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• pp.45-52
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• 2005

This research was performed to evaluate adsorption behavior of woody charcoals obtained from wood powder, fiber and bark of spruce (Abies sibirica Ledeb). The wood materials were carbonized at various temperatures for 1 hour using experimental rotary kiln without any inert gas. The adsorption capacity of iodine and toluene, specific surface area and removal efficiency of acetic acid and ammonia gas of those charcoals were measured. The higher was the temperature for carbonization, the lower yields of charcoals were. Ash content of bark charcoal was higher than that of wood powder charcoal or fiber charcoal. Elemental analysis of woody charcoal revealed that the content of carbon was gradually lincreased as carbonization temperature was higher. When carbonization temperature was higher, adsorption capacity of woody charcoals for iodine was much improved. Wood powder charcoal and fiber charcoal were more effective for iodine adsorption rather than bark charcoal. Capacity of toluene adsorption was the highest in the charcoal of $600^{\circ}C$. Charcoals produced at high temperature efficiently removed acetic acid gas, while charcoals carbonized at low temperature such as $400^{\circ}C$ were proper to remove ammonia gas. This difference may be explained that the acidity of charcoals depends on the carbonization temperature: charcoals of low temperature indicate acidic property, while those of high temperature turned to alkaline.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.6
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• pp.753-757
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• 1999

The growth of rotifer, Brachionus rotundiformis was evaluated at different culture conditions. Rotifer was fed on condensed freshwater Chlorella. The productivity of rotifer in the high density culture system was compared to that of rotifer in the batch culture system, in which rotifer was fed on baker's yeast. The growth rate of rotifer increased as temperature increased in the culture system supplied with air or oxygen gas. The maximum density of rotifer in the culture systems supplied with air was in range of 16,300$\~$17,000 ind./ml at $24^{\circ}C$. In the culture systems supplied with oxygen gas, it ranged 26,300$\~$30,500 ind/ml at $28^{\circ}C$. When the concentration of dissolved oxygen in the culture system supplied with air reached to below 1 ppm or when the concentration of undissolved ammonia in the culture system supplied with oxygen gas reached 16.6$\~$22.6 ppm, the growth of rotifer decreased. When oxygen gas was supplied and pH was adjusted to 7, the maximum density of rotifer reached to 43,000 ind/ml at $32^{\circ}C$. The production costs for 10 billion rotifer in the high density culture and batch culture were 693,000 and 961,000 won, respectively. Therefore, it was concluded that the productivity of rotifer in the high density culture was higher than that in a batch culture.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.2
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• pp.107-116
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• 1998

Coal gasification fuel has generally a lower calorific values than natural gas and also contains ammonia which is a main source of fuel NOx. Such a fuel is in need of the advanced technologies for the NOx reduction with higher combustion efficiency. Therefore fuel staged combustion was investigated for the fuel NOx control using a bench scale gas combustoi for the fuel NOx control. Parametric screening studies were performed with the variation of air ratio, retention length and reburning fuel. The NOx reduction efficiency was increased with an increase of total air ratio having optimum reburning air ratio differently, The Increased retention length of the reburning zone was preferable for NOx reduction. Hydrocarbonic reburning fuels like propane and butane were more effective for the NOx reduction efficiency than hydrogen fuel. The NOx concentration at exit was linearly increased according to the fuel-N the fuel.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.601-605
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• 2009

The paper deals with the proper design of GGH(gas-gas heater) panel elements of desulfurization equipments in a thermoelectric power plant. When fossil fuels such as coal, petroleum et cetera are burnt to ashes, sulfur oxide compounds are produced, and calcareous sludges are deposited at GGH panel elements. In this case, operation of a power plant equipments is interrupted, and a tremendous economic loss comes into existence. One of the purposes of the paper is to find flow velocity distributions and regions of depositions when calcareous sludges pile up on the GGH panel elements through the fluid analysis. In the fluid analysis, flow velocity and position distributions of particles between GGH panel elements are demonstrated according to time variation for ammonia and calcium hydroxide particles.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.1
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• pp.65-69
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• 1977

The characteristics of two stage compressor which is constituted of two separated reciprocating compressors was tested measuring the volumetric efficiency of each compressor at suction of both bighandlowpressdresideusillgorificetypeflolrmeters. The volumetric efficiency of low pressure side compressor was lower than that of the high side when they were operating under the same compression ratio. And it tended to reduce obviously by lowering evaporating temperature resulting in a markable reduction of refrigerating capacity at the same time. It is assumed that the falling of volumetric efficiency at low side compressor was directed by the decrease in evaporating temperature which derives the falls of gas pressure at suction, increase in compression ratio, and gas flow resistance at suction and discharge valves.