• Fire Science and Engineering
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• v.27 no.3
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• pp.66-71
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• 2013

The purpose of this study is to assess the criteria on a floor hinge and door closer for the optimum design of the access door of a smoke control room. The door opening force due to differential pressure is 60.75 N, 40.5 N, 32.91 N and 12.66 N when the differential pressure is 60 Pa, 40 Pa, 32.5 Pa and 12.5 Pa, respectively. The door opening force of the floor hinge and door closer to which the criteria of KS F 2806 are applied is 27.5 N, 40 N, 75 N, 100 N and 125 N for the Nos. 1, 2, 3, 4 and 5 class floor hinges and door closers, respectively. This study compared the differential pressure and opening force limits of floor hinges and door closers with the values specified in NFSC 501A and found that they exceeded the criteria specified in NFSC 501A. Therefore, it is necessary to reflect the differential pressure and smoke control wind speeds as well as the opening forces specified in NFSC 501A on the design of floor hinges and door closers. The installation conditions of floor hinges and door closers of access doors differ depending on the type and name of a smoke control damper. This study found that Nos. 1, 2 and 3 floor hinges and door closers could be installed for access doors with low differential pressure and that Nos. 1 and 2 floor hinges and door closers could be installed for access doors with normal differential pressure.

• Journal of Animal Science and Technology
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• v.53 no.1
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• pp.51-57
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• 2011

The performance of grass filter strips (GFS) in abating $NO_3$-N concentrations from the forage cropland was tested in an experiment on the 10% slope in Grassland and Forages Division, National Institute of Animal Science, Rural Development Administration (RDA) from October 2007 to September 2009. Forage croplands with rye-corn double cropping system applied with chemical fertilizer and livestock manure (LM) were compared in a natural condition. The plots were hydrologically isolated in a randomized block layout of 3 treatments $\times$ 2 factors $\times$ 3 replicates. Main plots consisted of the length of GFS, such as 0 m, 5 m, 10m and 15m. Sub plots consisted of the type of LM, such as chemical fertilizer (CF), cattle manure (CM) and swine manure (SM). Dry matter yields of rye and corn increased significantly in order of CF > CM > SM (p<0.05). Concentrations of $NO_3$-N in surface runoff water were reduced as the length of GFS increased. Especially, GFS with 10 m and 15m reduced $NO_3$-N concentrations significantly compared to that with 0 m and 5 m (p<0.05). The results from this study suggest that GFS improved the removal and trapping of manure nutrients from forage croplands.

• Environmental Engineering Research
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• v.16 no.4
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• pp.231-236
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• 2011

Biological nitrogen removal, using a continuous flow packed-bed reactor (CPBR) in a consecutive nitrification and denitrification process, was evaluated. An apparent decline in the nitrification efficiency coincided with the steady increase in $NH_4{^+}$-N load. Sustained nitrification efficiency was found to be higher at longer empty bed contact times (EBCTs). The relationship between the rate of alkalinity consumption and $NH_4{^+}$-N utilization ratio followed zero-order reaction kinetics. The heterotrophic denitrification rate at a carbon-tonitrogen (C/N) ratio of >4 was found to be >74%. This rate was higher by a factor of 8.5 or 8.9 for $NO_3{^-}$-N/volatile solids (VS)/day or $NO_3{^-}-N/m^3$ ceramic media/day, respectively, relative to the rates measured at a C/N ratio of 1.1. Autotrophic denitrification efficiencies were 80-90%. It corresponds to an average denitrification rate of 0.96 kg $NO_3{^-}-N/m^3$ ceramic media/day and a relevant average denitrification rate of 0.28 g $NO_3{^-}$-N/g VS/day, were also obtained. Results presented here also constitute the usability of an innovative porous sulfur ceramic media. This enhanced the dissolution rate of elemental sulfur via a higher contact surface area.

• ALGAE
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• v.32 no.4
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• pp.275-284
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• 2017

Microcystis aeruginosa causes harmful algal blooms in the Nakdong River of Korea. We studied the effect of different concentrations and ratios of ammonium ($NH_4{^+}$), nitrate ($NO_3{^-}$), and phosphate ($PO{_4}^{3-}$) on growth of this species in BG-11 medium: each nutrient alone, $NO_3{^-}:NH_4{^+}$ ratio, the N : P ratio with fixed total N (TN), and the N : P ratio with fixed total P (TP). The single nutrient experiments indicated that M. aeruginosa had the highest growth rate at $NH_4{^+}$ and $NO_3{^-}$ concentrations of $500{\mu}M$, and at a $PO{_4}^{3-}$ concentration of $5{\mu}M$. The $NO_3{^-}:NH_4{^+}$ ratio experiments showed that M. aeruginosa had the highest growth rate at a ratio of 1 : 1 when TN was $100{\mu}M$ and $250{\mu}M$, and the lowest growth rate at a ratio of 1 : 1 when the TN was $500{\mu}M$. The N : P ratio with fixed TN experiments indicated that M. aeruginosa had the highest growth rates at 50 : 1, 20 : 1, and 100 : 1 ratios when the TN was 100, 250, and $500{\mu}M$, respectively. In contrast, the N : P ratio with fixed TP experiments showed that M. aeruginosa had the highest growth rates at 200 : 1 ratio at all tested TP concentrations. In conclusion, our results imply that the $NO_3{^-}:NH_4{^+}$ ratio and the $PO{_4}^{3-}$ concentration affect the early stage of growth of M. aeruginosa. In particular, our results suggest that the maximum growth of M. aeruginosa is not simply affected by the $NO_3{^-}:NH_4{^+}$ ratio and the N : P ratio, but is determined by the TN concentration if a certain minimum $PO{_4}^{3-}$ concentration is present.

• Bulletin of the Korean Chemical Society
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• v.14 no.1
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• pp.47-52
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• 1993

The vibrational relaxation rate constants of NO(v = 1-7) by $O_2\;and\;N_2$ have been calculated in the temperature range of 300-1000 K using the solution of the time-dependent Schrodinger equation. The calculated relaxation rate constants by $O_2$ increase monotonically with the vibrational energy level v, which is compatible with the experimental data, while those by $N_2$ are nearly independent of v in the range of $3.40 {\pm}1.60{\times}10_{-16} cm^3$/molecule-sec at 300 K. Those for NO(v) + $N_2$ are about 2-3 orders of magnitude smaller than those for NO(v) + $O_2$, because the latter is an exothermic processes while the former an endothermic. Relaxation processes can be interpreted by single-quantum V-V transition. The contributions of V-T/R transition and double-quantum V-V transition to the relaxation are negligible over the entire temperature range.

• Journal of the Korean Chemical Society
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• v.47 no.3
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• pp.283-291
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• 2003

The purpose of this research was to analyze and improve the experiment, observing the color change under compression on the equilibrium of $2NO_2\;{\rightleftarrow}\;N_2O_4$ system, described in high school and general chemistry textbooks. Chemistry textbooks described that the reddish brown color got lighter on the compression of $2NO_2\;{\rightleftarrow}\;N_2O_4$ system. This misinterpretation was due to no consideration of $NO_2$ concentration increase by the volume decrease. In order to propose a correct interpretation, the changes of color and temperature on compression were quantitatively measured and compared with theoretical studies. In addition, an improved experiment, excluding the effect of $NO_2$ concentration increase, was proposed to observe only the color change of the net equilibrium shift.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1232-1238
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• 2011

This experiment was conducted to measure concentration of dissolved $N_2O$ in ground-water of 59 wells and to make emission factor for assessment of indirect $N_2O$ emission at agricultural sector in agricultural areas of Gyeongnam province from 2007 to 2010. Concentrations of dissolved $N_2O$ in ground-water of 59 wells were ranged trace to $196.6{\mu}g-N\;L^{-1}$. $N_2O$ concentrations were positively related with $NO_3$-N suggesting that denitrification was the principal reason of $N_2O$ production and $NO_3$-N concentration was the best predictor of indirect $N_2O$ emission. The ratio of dissolved $N_2O$-N to $NO_3$-N in ground-water was very important to make emission factor for assessment of indirect $N_2O$ emission at agricultural sector. The mean ratio of $N_2O$-N to $NO_3$-N was 0.0035. It was greatly lower than 0.015, the default value of currently using in the Intergovernmental Panel on Climate Change (IPCC) methodology for assessing indirect $N_2O$ emission in agro-ecosystems (IPCC, 1996). It means that the IPCC's present nitrogen indirect emission factor ($EF_{5-g}$, 0.015) and indirect $N_2O$ emission estimated with IPCC's emission factor are too high to use adopt in Korea. So we recommend 0.0034 as national specific emission factor ($EF_{5-g}$) for assessment of indirect $N_2O$ emission at agricultural sector. Using the estimated value of 0.0034 as the emission factor ($EF_{5-g}$) revised the indirect $N_2O$ emission from agricultural sector in Korea decreased from 1,801,576 ton ($CO_2$-eq) to 964,645 ton ($CO_2$-eq) in 2008. The results of this study suggest that the indirect Emission of nitrous oxide from upland recommend 0.0034 as national specific emission factor ($EF_{5-g}$) for assessment of indirect $N_2O$ emission at agricultural sector.

• Environmental Analysis Health and Toxicology
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• v.6 no.3_4
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• pp.133-141
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• 1991

Vermistabilization is the stabilization of organic wastes using earthworms. The worms maintain aerobic conditions in the waste, accelerating and enhancing the biological decomposition of the waste. This study was carried out to find out fundamental factors affecting the performance of the process such as temperature, moisture content and pH condition of nightsoil sludge, and to evaluate the worms excreta (casting) as fertilizer. The results could be summarized as follows; the optimum range of temperature was observed 10~3$0^{\circ}C$ while survival rate of eathworm decreased rapidly at 35$^{\circ}C$ within 6 days and death occurred at 5$^{\circ}C$. Those of moisture content and pH condition were 50~70% and 5~8, respectively. Earthworms were revealed to change the composition of N in nightsoil sludge consisting of$NH_3$-N (71%), $NO_2$-N (2%) and $NO_3$-N (27%) into that $NH_3$-N (24%), $NO_2$-N (1%), $NO_3$-N (75%) in earthworm excreta, respectively The concentrations of NH$_3$and H$_2$S gas in pig manure were reduced by 59.2% and 45.2% in case of mixing pig manure with casting.

• Journal of the Korean earth science society
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• v.41 no.6
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• pp.630-646
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• 2020

In rural areas, nitrate-nitrogen (NO3-N) pollution caused by agricultural activities is a major obstacle to the use of shallow groundwater as domestic water or drinking water. In this study, the water quality characteristics of shallow groundwater in Hyogyo-ri agricultural area of Yesan-gun, Chungcheongnam-do province was studied in connection with land use and chemical composition of soil layer. The average NO3-N concentration in groundwater exceeds the domestic and agricultural standard water qualities of Korea and is caused by anthropogenic sources such as fertilizer, livestock wastewater, and domestic sewage. The groundwater type mainly belongs to Ca(Na)-Cl type, unlike Ca-HCO3 type, a general type of shallow groundwater. The average NO3-N concentration (7.7 mg L-1) in groundwater in rice paddy/other (upstream, ranch, and residential) area is lower than the average concentration (22.8 mg L-1) in farm field area, due to a lower permeability in paddy area than that in farm field area. According to the trend analysis by the Mann-Kendall and Sen tests, the NO3-N concentration in the shallow groundwater shows a very weak decreasing trend with ~0.011 mg L-1yr-1 with indicating almost equilibrium state. Meanwhile, SO42- and HCO3- concentrations display annual decreasing trend by 15.48 and 13.15%, respectively. At a zone of 0 to 5 m below the surface, the average hydraulic conductivity is 1.86×10-5 cm s-1, with a greater value (1.03×10-4cm s-1) in sand layer and a smaller value (2.50×10-8 cm s-1) in silt layer.

• 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.