• Journal of Korean Society for Atmospheric Environment
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• v.12 no.4
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• pp.389-398
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• 1996

In order to understand the relative importance of various pathways leading to the production and transformation of aerosols under different atmospheric conditions, the behavior of atmospheric aerosols have been investigated using a high volume tape sample in Seoul for a week period during August 1990. The concentrations of anion $(SO^{2-}_4, NO^-_3, CI^-)$ and cation $(Ca^{2+}, Na^+, NH^+_4)$ species of aerosol samples were analyzed to identify the ionic composition of aerosols and to estimate their relative contributions to aerosol formation. The concentrations of aerosol species were calculated by a multiple regression model. The results of our calculations indicate the existence of various chemical species such as $(NH_4)_2SO_4, Na_2SO_4, CaSO_4, NH_4NO_3, NaNO_3, Ca(NO_3)_2, NH_4Cl$, and NaCl salts. According to our calculations, the most dominant species of aerosol was $(NH_4)_2SO_4$ with the mean concentration of 23.3 $/mu g/m^3$ (66.9%). The proportion of different componts with aerosol (e.g., $NH_4NO_3$ and $NH_4Cl$) was strongly affected by temperature, relative humidity, and partial presure of gases.

• Journal of the Korean Ceramic Society
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• v.41 no.12 s.271
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• pp.907-914
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• 2004

The nitridation mechanism of Si by SHS at $Si-NaCl-NH_{4}Cl-NaN_3$ system was investigated in this work. It was revealed that NaCl as a diluent was helpful to the perfect nitridation reaction by retarding the growth of Si particle resulted from the melting of Si at the initial stage of the nitridation reaction. And $NH_{4}Cl\;and\;NaN_3$ formed NaCl through decomposition and combination, and the preheating of pellet was helpful to the nitridation reaction in this process. The main nitridation mechanism of this system was liquid-gas reaction. The optimum porosity of the pellet for the nitridation of ${\alpha}-Si_{3}N_4$ was $67-69\%$.

• Applied Chemistry for Engineering
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• v.31 no.1
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• pp.90-96
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• 2020

This paper aims to reuse sewage by a forward osmosis using a blended fertilizer as a draw solution. This work deals with the primary sedimentation basin influent, effluent, and secondary sedimentation basin effluent from J sewage treatment plant. The average permeate water flux was higher in the order of the blend of KCl and NH₄Cl > KCl and NH₄H₂PO₄ > KCl and (NH₄)₂HPO₄, and the reverse solute flux was lower in the order of the blend of KCl and NH₄H₂PO₄ < KCl and NH₄Cl < KCl and (NH₄)₂HPO₄. Regardless of the blended fertilizer, the permeate water flux of the effluent from the secondary sedimentation basin was the highest. The blended fertilizer of KCl and NH₄H₂PO₄ was found to be most useful for the reuse of sewage because it contains nitrogen, phosphorus and potassium, which are the major components of a fertilizer, and has a low reverse solute flux. When the blend of KCl and NH₄H₂PO₄ was used as a draw solution, the average permeate water and reverse solute flux for the secondary sedimentation basin effluent were 12.14 L/㎡hr and 0.012 mol/㎡s, respectively.

• The Korean Journal of Ecology
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• v.26 no.3
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• pp.135-142
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• 2003

Four legume plants showed better growth by the external nitrogen supply rather than the symbiotic nitrogen fixation only under salt additions. In case of Glycine max and Phaseolus angularis, total nitrogen contents decreased by high salinity level but their amino acid levels significantly increased with the increase of salt treatments and indicated high soluble-/insoluble-N ratios. Cassia tora and Albizzia julibrissin contained less amino acids than G. max and P. angularis but total N (esp. insoluble N fraction) increased with higher salt levels. Asparagine occurred as a main amino acid especially in G. max and P. angularis and can be seen as potential N-storage form in these plants. It might be play an important role for the osmoregulation mechanism under the saline condition. Meanwhile, to investigate what kinds of nitrogen sources are effective for overcoming salt stress on soybean plants, various N forms and concentrations (NH₄NO₃-N, NO₃-N, NH₄NO₃-N; 2.5 and 5 mM) were additionally supplied to the salt gradient medium. Soybean plants treated with NH₄NO₃-N showed the best growth up to 40 mM NaCl and NO₃- fed plants indicated good growth even at 80 mM NaCl treatments. Contrary to NH₄NO₃- and NO₃- fed plants, NH₄/sup +/- fed plants showed remarkable growth reduction and died by 40 and 80 mM NaCl treatments after the first harvest (15th day). Consequently, these results suggest that salt excluding and resistant capacities of soybean plants under NaCl treatments are increased in order of NH₄ - N, control, NO₃- N and NH₄NO₃- N depending on N concentration except NH₄- N treatments.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.75-79
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• 2010

The precursor powders with thin wall structure were prepared by spray pyrolysis from the spray solution with ethylenediaminetetraacetic acid, citric acid and $NH_4Cl$ flux. The $BaMgAl_{10}O_{17}:Eu$ phosphor powders formed from the spray solution without organic additives and flux material had sizes of $1{\sim}5{\mu}m$ and hollow structure with high thickness at post-treatment temperature of $1,200^{\circ}C$. However, $BaMgAl_{10}O_{17}:Eu$ phosphor powders formed from the spray solution with ethylenediaminetetraacetic acid, citric acid and $NH_4Cl$ flux had fine size and plate-like shape. The mean crystallite sizes of the phosphor powders with fine sizes were 23, 35, and 33 nm when the content of $NH_4Cl$ flux were 0, 6, 35 wt% of phosphor. The photoluminescence intensity of the phosphor powders formed from the spray solution with the optimum amount of $NH_4Cl$ flux as 35 wt% was 215% of that of the phosphor powders formed from the spray solution without flux material.

• Analytical Science and Technology
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• v.5 no.4
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• pp.349-358
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• 1992

The direct determination of lead in the whole-blood by graphite furnace atomic absorption spectrometric analysis was carried out by using the sample which was diluted five-fold with 1% Triton X-100. Matrix modification was tried to remove the interferences of blood matrix and also to get the optimum analytical condition. Good agreement with certificated values in reference materials(bovine blood) supplied by comparison program in Japan was obstained when 1% $(NH_4)_2HPO_4$ as matrix modifier and ashing temperature, $700^{\circ}C$ were used or 1% $(NH_4)_2HPO_4$ and 0.1% $PdCl_2$ as matrix modifier and ashed at $700^{\circ}C$. Standard deviations were appeared as 2.2~6.3% for 1% $(NH_4)_2HPO_4$ and 3.1~9.1% for 1% $(NH_4)_2HPO_4$ and 0.1% $PdCl_2$ in the range of $31{\sim}624{\mu}gPb/l$.

• Journal of Korean Society of Forest Science
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• v.79 no.3
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• pp.285-289
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• 1990

Soil N mineralization and nitrification can be measured conveniently using mixed bed (cation and anion) exchange resin bags. However, appropriate use of these resin bags requires pretreatment to avoid colorimetric interference and standardize N ion adsorption. Three pretreatments were evaluated : control (untreated), 2 M NaCl with a distilled water rinse, and 4 M NaCl. The 4 M NaCl treatment was effective at removing background levels of $NH_4{^+}$ and $NO_3{^-}$, but adsorbed low amounts (about 40%) of inorganic N from standard solutions. Untreated resin bags adsorbed a constant, higher amount of $NO_3{^-}$ (60%), but did not remove background levels of $NH_4{^+}$. The 2 M NaCl treatment followed by a distilled water rinse performed best : it removed background $NH_4{^+}$ and adsorbed a constant amount of both $NH_4{^+}$ (70%) and $NO_3{^-}$ (60%). Because the ion exchange resin is fairly expensive, we also tested if the resin bags could be reused. Resin bags were either loaded with $NH_4{^+}$ and $NO_3{^-}$ in the laboratory or incubated in soil in the field, desorbed with the 2 M NaCl treatment, and then loaded with standard $NH_4{^+}$ and $NO_3{^-}$ solutions. Lab loaded resin bags adsorbed about 60% of inorganic N then loaded with 2.5 or $5.0mgN\;1^{-1}$ and 70% when loaded at 10 or $20mgN\;1^{-1}$, whereas reused field incubated bags showed the opposite adsorption efficiency. These results demonstrate that resin bags can give reproducible results, but care must be taken to evaluate the effect of pretreatment and potential for reuse.

• Journal of Environmental Science International
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• v.11 no.4
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• pp.347-353
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• 2002

This study was conducted to investigate the characteristics of chloramination as a secondary disinfection in a drinking water distribution system. At the range from pH 6 to pH 8, monochloramine was predominant with a trace of dichloramine, and the free chlorine was detected after breakpoint. At $25^{\circ}C$, the breakpoints of pH 6, 7 and 8 appeared when the weight ratios of chlorine to ammonia nitrogen were 11:1, 9:1 and 10:1 respectively, and the peak points on the breakpoint curves at pH 6, 7 and 8 were in the Cl$_2$ / NH$_3$-N ratio of 9:1, 6:1 and 5:1 respectively. As pH increased from 6 to 8, maximum point of monochloramine on the breakpoint curve was moved from 7:1 to 5:1 in the weight ratio of chlorine to ammonia nitrogen. The maximum concentration of monochloramine was formed at the pH values of 7~8 and in the Cl$_2$ / NH$_3$-N ratio below 5:1. As the Cl$_2$/NH$_3$-N ratio increased and the pH lowered, chloramines decay proceeded at an increased rate, and residual chloramines lasted longer than the residual free chlorine. The monochloramine and the dichloramine were formed at pH 6, and then the dichloramine continued increasing with contact time.

• Journal of Korean Society for Atmospheric Environment
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• v.5 no.2
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• pp.1-11
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• 1989

Sandy dust phenomena was observed from April 19 to 23, 1988 in Seoul. During this period it rained and the precipitation was collected to investigate the rain chemistry. This study was carried out to analyzed the chemical composition of precipitation by the measurements of conditivity, cations $(H^+, NH_4^+, K^+, Na^+, Ca^{2+}, MG^{2+})$, and anions $(SO_4^{2-}, NO_3^-, Cl^-, F^-, Br^-)$ which are believed to be the major ions playing an important role in the acidity of rain water. During the period of sandy dust phenomena the range of pH value and conductivity concentration of rainwater were 6.0-6.7, 172-254 $\mu \mho/cm$. The anions and cations concentrations increased and the orders of these concentrations were $SO_4^{2-} > Cl^- > NO_3^- > Na^+ > Ca^{2+} > NH_4^+ > Mg^{2+}$. THe principal chemical compounds of rainwater were estimated at $(NH_4)_2 SO_4, CaSO_4, NaCl, and MgCl_2$.

• Journal of Korean Society of Water Science and Technology
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• v.26 no.6
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• pp.27-42
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• 2018

This study analyzed the utility of ammonium chloride ($NH_4Cl$) as a nitrogen source for methanotroph communities. When cultured in nitrate mineral salt (NMS) medium, the methanotroph community we identified four families, seven genera, and 16 type I and type II species of methanotrophs. Among species in the Methylobacter genus, Methylobacter marinus could be actively cultured in NMS medium without NaCl addition. Following the addition of 25 mM $NH_4Cl$, the numbers of the type I genera Methylomonas, Methylococcus, and Methylobacter were increased, whereas the numbers of the type II genera Methylocystis and Methylosinus were decreased after 5 days. In methanotroph communities, certain concentrations of $NH_4Cl$ affected methane consumption and growth of methanotrophs at the community level. $NH_4Cl$ caused a considerable decrease in the methane consumption rate and the expression of soluble methane monooxygenases (sMMOs) but did not inhibit the growth of Methylomonas methanica expressing sMMO. These results could be attributed to competitive antagonism of MMOs due to their direct involvement in ammonia oxidation.