• Journal of Energy Engineering
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• v.19 no.3
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• pp.182-187
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• 2010

This study was the effect of inserting CO tube on $NO_x$ and CO emission characteristics in a compact combustion chamber. In detail, $NO_x$ and CO emission characteristics with changing of distance due to inserting CO tube between a burner and a main heat exchanger were investigated. For this study, the commercial program, FLUENT with GRI 2.11 detail reaction mechanism, was used for the numerical study and a commercial heat exchanger was tested for the experimental study. As results, when the CO tube was inserted between a burner and a main heat exchanger, it was verified that $NO_x$ and CO emissions was decreased simultaneously as CO tube was closed to a burner and the distance between CO tube and a main heat exchanger was increased.

• Environmental Engineering Research
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• v.21 no.3
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• pp.291-296
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• 2016

Application of photocatalytic nanoparticles has been recently gaining an increased attention as air purifying material for sustainable urban development. The present work reports the photocatalytic removal of gaseous phase nitrogen oxides ($NO_x$) using $TiO_2$-coated zeolite to be applied as a filter media for the urban green infrastructure such as raingardens. The $TiO_2$-coated zeolite was synthesized by simple wet chemistry method and tested in a continuous-flow photo-reactor for its removal efficiency of $NO_x$ under different conditions of the weight percentage of $TiO_2$ coated on the zeolite, and gas retention time. The removal efficiency of $NO_x$ in general increased as the weight percentage of $TiO_2$ coated on the zeolite increased up to 15-20%. Greater than 90% of $NO_x$ was removed at a retention time of one minute using the $TiO_2$-coated zeolite ($TiO_2$ weight percentage = 20%). Overall, $TiO_2$-coated zeolite showed greater efficiency of $NO_x$ removal compared to $TiO_2$ powder probably by providing additional reaction sites from the porous structure of zeolite. It was presumed that the degradation of $NO_x$ is attributed to both the physical adsorption and photocatalytic oxidation that could simultaneously occur at the catalyst surface.

• Korean Journal of Biological Psychiatry
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• v.13 no.1
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• pp.19-25
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• 2006

Background : Some reports have suggested that decreased nitric oxide metabolites($NO_x$) and activity of nitric oxide synthase could be related to the pathophysiology of depression. We evaluated plasma levels of $NO_x$ in pregnant women with and without postpartum depression at prenatal and postnatal period. Methods : The plasma concentrations of $NO_x$ were measured in 104 pregnant women in the third trimester and at 6 weeks postpartum and in 64 normal controls. The severity of depression and anxiety was measured with the Edinburgh Postnatal Depression Scale(EPDS), Beck Depression Inventory(BDI), and Beck Anxiety Scale(BAI). Results : Plasma $NO_x$ levels at 6 weeks postpartum were significantly lower in cases of postpartum major depression(EDPS scores${\geq}$13 points) than in cases without depression(EDPS scores${\leq}$9 points). Plasma $NO_x$ levels had significantly negative correlation with EPDS scores at 6 weeks postpartum. Conclusion : We demonstrate that decreased plasma $NO_x$ is associated with postpartum depression. Further studies are required to determine whether individual serum concentration of plasma $NO_x$ alone could predict maternal depression.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.486-492
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• 2022

Nitrogen oxides (NO_x; NO and NO₂) are major air pollutants and can cause harmful effects on the human body. Electron Beam Flue Gas Treatment (EBFGT) is a technology that generates electrons with an energy of 0.5-1 MeV using electron accelerators and effectively processes exhaust gases. In this study, NO_x was removed using an electron beam accelerator with spraying additives (NaOH and NH₄OH). NO and NO₂ were 100% and more than 94% removed, respectively, at an electron beam absorbed dose of 20 kGy and an additive concentration of 0.02 M (mol/L). In most cases, NO_x was removed better with lower initial NOx concentrations and higher electron beam absorbed doses. As the irradiation strength (mA) of the electron beam increases, the probability of electron impact on the material accordingly rises, which may lead to increase removal efficiency. The results of the present study show that the continuous electron beam process using additives achieved more effective removal efficiency than either individual process (wet-scrubbing or EB irradiation only).

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.3
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• pp.315-323
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• 2003

The goal of this study if the optimization of discharge electrode for pulsed corona discharge reactor located in thermal power plant. For this purpose, we have performed experiments of NO$_{x}$ removal rate by exchange of discharge electrode diameter and arrangement of discharge electrode in the non -thermal plasma reaction facility using a ethylene as additive. If the diameter and numbers of discharge electrode were larger, the NO$_{x}$ removal rate was higher. From these results, if we optimized the shape and installed numbers of discharge electrode at the pilot plant, we could increase the NO$_{x}$ removal rate with less amount of additive than current amount.mount.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.1
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• pp.37-43
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• 2000

In this experimental study we proposed the double dielectric barrier discharge (DDBD) reactor to produce as high an electric field as possible. The experiment are conducted for applied voltage from 15 to 20[kV], $1~4[\ell/min]$ of gas flow rate and 120[Hz] and 240[Hz] of pulse rate. Superposition discharge(SPD) generated in DDBD which combined the surface discharge with the silence discharge was the most effective to reduce the $NO_x$. In the decomposition efficiency per watt, the low pulse rate gave better efficiency than the high pulse rate. However in DeNOx rate, the high pulse rate gave better performance than the low pulse rate. $NO_x$ removal rate and efficiency increased with increasing the applied voltage in all reactors.

• Journal of Korean Society for Atmospheric Environment
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• v.7 no.1
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• pp.31-40
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• 1991

This study shows the correlation between $NO_x$ emission in the exhaust gas and various operation factors of dual fuel engine for Co-generation system. General tendency was shown that the thermal efficiency was lowered by the change of operation factors. However these were not confirmed on this experiment. Increasing T4 temperature (exhaust gas temperature at turbo-charger inlet) reduces $NO_x$ emission rate. The higher T4 temperature requires lower excess air as the excess air ratio is controlled by T4 temperature on gas mode operation. Another tendency was that $NO_x$ emission rate is reduced in case of increasing boost air temperature, quantity of pilot oil or bypassing flue gas through the exhaust gas boiler. The diameter of the fuel injection nozzle was changed smaller than design value and the injection timing was readjusted. Thus $NO_x$ emission rate could be reduced as retarding injection timing and changing hole diameter of fuel injection nozzle, however maxium engine out-put was decreased by changing fuel nozzle on the diesel mode operation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.485-490
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• 2004

Sawtooth mixing device used in a non-premixed burner is evaluated for flame stabilization and NO$_{x}$ reduction. Three mixers with different blade angles are tested. Methane is delivered through the fuel jet and air passes through the co-flow annulus. The flame mode changes (attached flame, lifted flame and extinction) against the fuel flow speed are measured, and the stability diagram is drawn. Moreover, by traversing thermocouple and sampling probe in the flame, the distribution of temperature and NO$_{x}$ mole fraction are measured. With the change in blade angle, flame shape, flame stabilization, the distribution of temperature and NO$_{x}$ mole fraction are changed considerably.rably.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.1-3
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• 2013

The premixed combustion system applying exhaust gas recirculation was investigated to achieve the low pollutant emission and the high thermal efficiency. In this study, it was studied the effects of EGR on the thermal efficiency, $NO_x$ and CO emissions with various EGR ratios and equivalence ratios. As results, when equivalence ratio was increased, thermal efficiency increased and $NO_x$ and CO concentration increased. When EGR was applied, $NO_x$ and CO concentration decreased and thermal efficiency increased. Especially, in the case of 15% of EGR ratio at 0.85 of equivalence ratio, $NO_x$ and CO concentration will be a smaller than these of a current operating condition of the boiler and thermal efficiency was about 1.7% higher.

• Journal of the Korean Society of Safety
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• v.12 no.2
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• pp.95-101
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• 1997

The confidence of new technology development for NO_x$ components elimination is obtained as conclusion based 1ike followings ; 1) The technology using PSC spark is a excellent methods for NO_x$ components elimination above 70% without by-product pollutants. 2) Some materials like Oxygen, Vaporized Water and Ammonia, increase the of NO_x$ elimination by staged addition. 3) Environmental conditions like pulse frequency and peak voltage are the important dosing factors for pollutants elimination effects. 4) As the PSC technic is the up-to-date one for pollutions elimination the research and development must be executed continuously for the purpose of theoretical establishment. And the application field must be broaden in future.