• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.2
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• pp.95-101
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• 1995

Experiments have been conducted to investigate the characteristics of formaldehyde and nitrous oxide formation from the catalytic reaction of methane. Catalysts used in the experiment were Pd. Pd/Pt/Rh loaded on ${\gamma}-Al_2O_3$ and ${\gamma}-Al_2O_3-La_2O_3$ monolith. In the catalytic reaction of methane. as the concentration of NO, $O_2$ and $CH_4$ increased, the formaldehyde emission was increased. The concentration of $N_2O$ increased as NO and CO increased. It was also found that the formaldehyde emission was produced by the gas reaction of methane in high temperature above 950K.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.12
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• pp.672-678
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• 2017

In this study, municipal solid waste (MSW) has collected 3 times and physico-chemical analysis has done. Nitrous oxide emissions from MSW incineration plant were measured continuously by EPA Method 18 and it was compared with the emission by calculation using the emission factor. The $N_2O$ emission of MSW incineration plant was more than twice as large as the emission by calculation. It was found that the installation of abatement facilities in MSW incineration plant is effective in achieving the greenhouse reduction targets and it can be ensure economical efficiency through emission trading system.

• 전자공학회논문지 IE
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• v.43 no.2
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• pp.7-10
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• 2006

A GaN-based metal-insulator-semiconductor (MIS) structure has been fabricated by using $BaTa_2O_6$ instead of conventional oxide as insulator gate. The leakage current o) films are in order of $10^{-12}-10^{-13}A/cm^2$ for GaN on $Al_2O_3$(0001) substrate and in order of $10^{-6}-10^{-7}A/cm^2$ for GaN on GaAs(001) substrate. The leakage current of thses films is governed by space-charge-limited current over 45 MV/cm in case of GaN on $Al_2O_3$(0001) substrate and by Poole-Frenkel emission in case of GaN on GaAs(001).

• Journal of Korean Society of Environmental Engineers
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• v.34 no.2
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• pp.86-90
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• 2012

The gaseous product of nitrogen cycle, nitrous oxide ($N_2O$) is a potent greenhouse gas whose Global Warming Potential (GWP) is about 300 times greater than $CO_2$. The dynamics of $N_2O$ emission are controlled by such environments and soil conditions. The main aim of this study is to investigate variations of $N_2O$ emission and its controlling factors with different land-use patterns in Haean basin. A forest, a radish field and a rice paddy were selected as three different land-use patterns. Their $N_2O$ emissions were measured every month during a growing season. We also collected soil samples with seasons and analyzed soil characteristics including inorganic nitrogen content. $N_2O$ emission was greatest at the radish field likely due to anthropogenic nitrogen addition by fertilization. Soils of forest and rice paddy also contained inorganic nitrogen originated from organic matter. However, the spatial variation was great and it looks that nitrogen cycle and $N_2O$ production were slower than that of radish field. Intensive observation and control of fertilization would be requiredto adjust $N_2O$ emission from agriculture soils.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1051-1056
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• 2014

Nitrous oxide ($N_2O$) is naturally generated from biological activity, such as bacteria's material exchange. However, recent $N_2O$ concentration in the atmosphere has being increased by the human activities such as industrial growth. One of factors to increase $N_2O$ concentration in the atmosphere is a $N_2O$ emission caused by the combustion of marine fuel oils. The marine transportation presently handles over 99 percent of the international freight cargoes and the number of ship is continuously increasing with increment of cargoes. In this study, author conducted a series of the experimental investigations on which combustion of fuels containing different element concentrations used in a 4-stroke marine diesel engine affect $N_2O$ emissions in the exhaust gas. Moreover, it is assessed on the extent to which fuel combustion patterns in the combustion chamber affect $N_2O$ emissions.

• Journal of the Korean institute of surface engineering
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• v.34 no.5
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• pp.403-408
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• 2001

In this work, the cyclic perfluorinated ether (c-C$_4$F$_{8}$O) with very high destructive removal efficiency (DRE) than other alternative gases, such as $C_3$F$_{8}$, c-C$_4$F$_{8}$ and NF$_3$ was used as an alternative process chemical. The plasma cleaning of silicon nitride using gas mixtures of c-C$_4$F$_{8}$O/O$_2$ and c-C$_4$F$_{8}$O/O$_2$+ $N_2$ was investigated in order to evaluate the effects of adding $N_2$ to c-C$_4$F$_{8}$O/O$_2$ on the global warming effects. Under optimum condition, the emitted net perfluorocompounds (PFCs) during cleaning of silicon nitride were quantified and then the effects of additive $N_2$ by obtaining the destructive removal efficiency (DRE) and the million metric tons of carbon equivalent (MMT-CE) were calculated. DRE and MMTCE were obtained by evaluating the volumetric emission using. Fourier transform-infrared spectroscopy (FT-IR). During the cleaning using c-C$_4$F$_{8}$O/O$_2$+$N_2$, DRE values as high as (equation omitted) 98% were obtained and MMTCE values were reduced by as high as 70% compared to the case of $C_2$F$_{6}$O$_2$. Recombination characteristics were indirectly investigated by combining the measurements of species in the chamber using optical emission spectroscopy (OES), before and after the cleaning, in order to understand any correlation between plasma and emission characteristics as well as cleaning rate of silicon nitride.silicon nitride.

• Korean Journal of Materials Research
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• v.21 no.5
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• pp.250-254
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• 2011

We have synthesized bluish-green, highly-efficient $BaSi_2O_2N_2:Eu^{2+}$ and $(Ba,Sr)Si_2O_2N_2:Eu^{2+}$ phosphors through a conventional solid state reaction method using metal carbonate, $Si_3N_4$, and $Eu_2O_3$ as raw materials. The X-ray diffraction (XRD) pattern of these phosphors revealed that a $BaSi_2O_2N_2$ single phase was obtained. The excitation and emission spectra showed typical broadband excitation and emission resulting from the 5d to 4f transition of $Eu^{2+}$. These phosphors absorb blue light at around 450 nm and emit bluish-green luminescence, with a peak wavelength at around 495 nm. From the results of an experiment involving Eu concentration quenching, the relative PL intensity was reduced dramatically for Eu = 0.033. A small substitution of Sr in place of Ba increased the relative emission intensity of the phosphor. We prepared several white LEDs through a combination of $BaSi_2O_2N_2:Eu^{2+}$, YAG:$Ce^{3+}$, and silicone resin with a blue InGaN-based LED. In the case of only the YAG:$Ce^{3+}$-converted LED, the color rendering index was 73.4 and the efficiency was 127 lm/W. In contrast, in the YAG:$Ce^{3+}$ and $BaSi_2O_2N_2:Eu^{2+}$-converted LED, two distinct emission bands from InGaN (450 nm) and the two phosphors (475-750 nm) are observed, and combine to give a spectrum that appears white to the naked eye. The range of the color rendering index and the efficiency were 79.7-81.2 and 117-128 lm/W, respectively. The increased values of the color rendering index indicate that the two phosphor-converted LEDs have improved bluish-green emission compared to the YAG:Ce-converted LED. As such, the $BaSi_2O_2N_2:Eu^{2+}$ phosphor is applicable to white high-rendered LEDs for solid state lighting.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.12
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• pp.1805-1811
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• 2016

The goal of this study was to estimate the emissions of greenhouse gases (GHG), namely methane ($CH_4$), nitrous oxide ($N_2O$), and carbon dioxide ($CO_2$) from poultry and pig production in South Korea over the last 10 years (2005 through 2014). The calculations of GHG emissions were based on Intergovernmental Panel on Climate Change (IPCC) guidelines. Over the study period, the $CH_4$ emission from manure management decreased in layer chickens, nursery to finishing pigs and gestating to lactating sows, but there was a gradual increase in $CH_4$ emission from broiler chickens and male breeding pigs. Both sows and nursery to finishing pigs were associated with greater emissions from enteric fermentation than the boars, especially in 2009. Layer chickens produced lower direct and indirect $N_2O$ emissions from 2009 to 2014, whereas the average direct and indirect $N_2O$ emissions from manure management for broiler chickens were 12.48 and $4.93Gg\;CO_2-eq/yr$, respectively. Annual direct and indirect $N_2O$ emissions for broiler chickens tended to decrease in 2014. Average $CO_2$ emission from direct on-farm energy uses for broiler and layer chickens were 46.62 and $136.56Gg\;CO_2-eq/yr$, respectively. For pig sectors, the $N_2O$ emission from direct and indirect sources gradually increased, but they decreased for breeding pigs. Carbon dioxide emission from direct on-farm energy uses reached a maximum of $53.93Gg\;CO_2-eq/yr$ in 2009, but this total gradually declined in 2010 and 2011. For boars, the greatest $CO_2$ emission occurred in 2012 and was $9.44Gg\;CO_2-eq/yr$. Indirect $N_2O$ emission was the largest component of GHG emissions in broilers. In layer chickens, the largest contributing factor to GHG emissions was $CO_2$ from direct on-farm energy uses. For pig production, the largest component of GHG emissions was $CH_4$ from manure management, followed by $CO_2$ emission from direct on-farm energy use and $CH_4$ enteric fermentation emission, which accounted for 8.47, 2.85, and $2.82Gg-CO_2/yr$, respectively. The greatest GHG emission intensity occurred in female breeding sows relative to boars. Overall, it is an important issue for the poultry and pig industry of South Korea to reduce GHG emissions with the effective approaches for the sustainability of agricultural practices.

• Journal of ILASS-Korea
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• v.25 no.3
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• pp.132-138
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• 2020

N₂O is hazardous atmosphere pollution matter which can damage the ozone layer and cause green house effect. There are many other nitrogen oxide emission control but N₂O has no its particular method. Preventing further environmental pollution and global warming, it is essential to control N₂O emission from industrial machines. In this study, the thermal decomposition experiment of N₂O gas mixture is conducted by using cylindrical reactor to figure out N₂O reduction and NO formation. And CHEMKIN calculation is conducted to figure out reaction rate and mechanism. Residence time of the N₂O gas in the reactor is set as experimental variable to imitate real SNCR system. As a result, most of the nitrogen components are converted into N2. Reaction rate of the N₂O gas decreases with N₂O emitted concentration. At 800℃ and 900℃, N₂O reduction variance and NO concentration are increased with residence time and temperature. However, at 1000℃, N₂O reduction variance and NO concentration are deceased in 40s due to forward reaction rate diminished and reverse reaction rate appeared.

• Korean Journal of Environmental Agriculture
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• v.36 no.2
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• pp.73-79
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• 2017

BACKGROUND: Carbonized biomass is a carbon-rich solid product obtained by the pyrolysis of biomass. It has been suggested to mitigate climate change through increased carbon storage and reduction of greenhouse gas emission. The objective of this study was to evaluate carbon dioxide ($CO_2$) and nitrous oxide ($N_2O$) emissions from soil after carbonized biomass addition. METHODS AND RESULTS: The carbonized biomass was made from a pyrolyzer, which a reactor was operated about $400{\sim}500^{\circ}C$ for 5 hours. The treatments were consisted of a control without input of carbonized biomass and two levels of carbonized biomass inputs as 6.06 Mg/ha for CB-1 and 12.12 Mg/ha for CB-2. Emissions of $CO_2$ and $N_2O$ from orchard soil were determined using closed chamber for 13 weeks at $25^{\circ}C$ of incubation temperature. It was shown that the cumulative $CO_2$ were $209.4g\;CO_2/m^2$ for CB-1, $206.4g\;CO_2/m^2$ for CB-2 and $214.5g\;CO_2/m^2$ for the control after experimental periods. The cumulative $CO_2$ emission was similar in carbonized biomass input treatment compared to the control. It was appeared that cumulative $N_2O$ emissions were $4,478mg\;N_2O/m^2$ for control, $3,227mg\;N_2O/m^2$ for CB-1 and$ 2,324mg\;N_2O/m^2$ for CB-2 at the end of experiment. Cumulative $N_2O$ emission contents significantly decreased with increasing the carbonized biomass input. CONCLUSION: Consequently the carbonized biomass from byproducts such as pear branch residue could suppress the soil $N_2O$ emission. The results fromthe study imply that carbonized biomass can be utilized to reduce greenhouse gas emission from the orchard field.