• Journal of Animal Science and Technology
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• v.51 no.4
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• pp.337-342
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• 2009

The feasibility of reutilization of magnesium ammonium phosphate (MAP) or struvite slurry recovered from the process through microwave irradiation was studied in this experiment. For this purpose, 4 different operations were performed with or without Mg source addition and different levels of MAP recycled in a batch reactor. Dissolution rate of MAP, ${NH_4}^+$ elimination pattern and physicochemical changes of MAP during microwave irradiation were also studied. The result showed that only 33% orthophosphate ($PO_4-P$) and 27% $NH_4-N$ removal occurred without adding any external Mg source (run A), whereas 87% $PO_4-P$ and 40% $NH_4-N$ removed when 1.0 M ratio of $MgCl_2$ (run B) was added based on $PO_4-P$ in influent. Although the addition of 1.0 molar ratio of microwave irradiated MAP (Run C) removed lower $PO_4-P$ and $NH_4-N$ than 1.0 M $MgCl_2$ (run B), $PO_4-P$ removal was double when compared with no Mg addition (run A). Addition of half MAP and half $MgCl_2$ (run D) showed the similar removal efficiency (88% $PO_4-P$ and 35% $NH_4-N$) with sole $MgCl_2$ addition (run B). Based on these results, the reutilization of MAP irradiated by microwave would be a feasible way to enhance the removal efficiencies of N and P, as well as curtail the Mg chemical usage. Track study showed that $NH_4-N$ gradually increased at initial stage of microwave irradiation of MAP, and then started eliminating from liquor as temperature increased over $45^{\circ}C$. Dissolution rate of ${PO_4}^{-3}$ during microwave irradiation was proportional to the initial MAP concentration, having $0.0091x^{0.6373}$ mg/sec. It was found from the scanning electron microscope (SEM) study that physical structure of MAP crystal started breaking down into small cube granules within very short time by electromagnetic vibration force during microwave irradiation and then gradually melted down into solution.

• Korean Journal of Soil Science and Fertilizer
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• v.15 no.2
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• pp.141-146
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• 1982

Laboratory and greenhouse experments were conducted to find out the optimum dilution time of methane fermented effluent of hog waste which was high pH (7.85), $NH_4$-N (683ppm), electric conductivity (8.3mmhos/cm) and BOD (about 1,000ppm) and the interval of effluent change which will provide maximun yield of green algae (Scenedesmus accuminatus), duck weed (Lemner minor L.) and Azolla anabaena (Azolla pinnata). The results of this experiment are summerized as follows. 1. The maximum yield were obtained at 5 times diluted effluent ($NH_4$-N : 137ppm) and exchange of 4 day intertval, from 25 times to 50 times dilution ($NH_4$-N : 7-14ppm) and 4 day interval, and 50 times dilution ($NH_4$-N : 14 ppm) and exchange the effluent at 4-8 day interval for green algae, duck weed and azolla growth, respectively. 2. Purification of the effluent was enhenced by growth of the green algae, duck weed and azolla due to decrease of pH, $MH_4$-N and electric conductivity of effluent. The degree of purification was higher in case of azolla growth than duck week growth.

• Korean Journal of Soil Science and Fertilizer
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• v.15 no.4
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• pp.270-276
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• 1982

Water culture experiment with mulberry (Morus alba L.)was carried out to investigate the ionic composition in the exudate and the ionic content in the organs (leaves, petioles, stem cortex, and roots) of mulberry tree with three different nitrogen sources ($NO_3-N$, $NH_4-N$, and $NH_4NO_3$). 1. Amount of exudate was much lower for $NH_4-N$ than for $NO_3-N$. 2. Total nitrogen content in the exudate was the highest in the NH4-N, the order of 2.2 times than in the $NO_3-N$. However, total nitrogen amount absorbed by tree per hour was proportional with the exudate amount. As the result, total nitrogen amount was higher 1.6 times in $NO_3-N$ ($289.6\;me\;plant^{-1}\;hr^{-1}$ than in $NH_4-N$. 3. Ammonium nitrogen depressed $Ca^{2+}$ uptake critically and even all of the anions, whereas $Mg^{2+}$, $K^+$ and $Na^+$ affected little. 4. Reduction of $NO_3$ may occured both in root and in leaves. 5. Content of cations and anions was highest in petioles, except $Ca^{2+}$ which was highest in leaves. As the result, petioles may be the storage organ of nutrients. 6. By increasing $NH_4-N$, ionic balance (C-A) decreased proportionally. 7. Nutrients amount in the exudate were approximatelly proportional with the amount in the roots. This suggested that roots may be the part diagnosed for nutrients. Being the sum of anions (${\Sigma}A$) higher than that of cations (${\Sigma}C$) in the roots, the ionic balance showed negative value.

• Journal of Environmental Science International
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• v.7 no.4
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• pp.505-510
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• 1998

This study has been carried out to investigate Electrostatic Precipitator's(ESP) performance enhancement and removal efficiency of fine particle according to (NH4)2SO4injection rate. The following conclusions are derived from the these test results : 1) For plant condition cases, according to the variation of concentration agent [(NH4)2SO4]-10ppm, when inlet dust loading was 2g/m2. And when Inlet dust loading was 3g/m", that was increased to 98 19% 99.16% 99.23%, 99.58%, 2) It Is seen from thins experiments that the increasing 30ppm concentration of (NH4)2SO4 increase the collection efficiency and fine particle omission control.

• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.792-799
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• 2019

The present study aims to investigate the fluorination of thorium oxide ($ThO_2$) by ammonium hydrogen difluoride ($NH_4HF_2$). Fluorination was performed at room temperature by mixing $ThO_2$ and $NH_4HF_2$ at different molar ratios, which was then left to react for 20 days. Next, the mixtures were analyzed using X-ray diffraction (XRD) at the intervals of 5, 10, 15, and 20 days, followed by the heating of the mixtures at $450-750^{\circ}C$ with argon gas flow. The characterization of $ThF_4$ was established using X-ray diffraction (XRD) and scanning electron microscopy-dispersion X-ray spectroscopy (SEM-EDX). In this study, ammonium thorium fluoride was synthesized through the fluorination of $ThO_2$ at room temperature. The optimum molar ratio in synthesizing ammonium thorium fluoride was 1.0:5.5 ($ThO_2:NH_4HF_2$) with 5 days reaction time. In addition, the heating of ammonium thorium fluoride at $450^{\circ}C$ was sufficient to produce $ThF_4$. Overall, this study proved that $NH_4HF_2$ is one of the fluorination agents that is capable of synthesizing $ThF_4$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.4
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• pp.379-385
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• 1987

A field experiment was conducted to find out the effects of liming (soil pH) and sources of N on the chemical constituents of soil and leaf lamina of burley tobacco. Treatments consisted of liming (nonliming, liming to soil pH 5.5 and 6.5) as the main plot and N sources［compound fertilizer of containing 3.9% $NH_4-N$ and 6.1% $NH_2-N,\;NaNO_3,\;(NH_2)_2CO\;and\;(NH_4)_2SO_4$］as the sub-plot. The soil pH was high in $NaNO_2$ plot, while low in $(NH_4)_2SO_4$. But the differences of Ca concentration in top soil among N sources were not detected. The $NO_3-N$ concentration in top soil was high in high limed and $NaNO_3$ plot. The $NO_3-N$ content of leaf (lamina) at 75 days after transplanting was high in $NaNO_3$ plot and CaO con-tent of leaf at 45 days after transplanting was high in high limed plot. But neither liming nor N source had effect on the contents of total nitrogen, $P_2-O_{5}\;and\;K_2O$ of leaf during growing season. There was no significant differences in total alkaloid and total nitrogen contents of cured leaf (lamina) to liming and N source. But when the source of N was $NaNO_3$, the content of total alkaloid was increased by adding lime. When the source of N was $(NH_4$)_2SO_4$, the content of $K_2O$ in cured leaf was high while CaO was low. But neither liming nor N source had effect on the contents of $P_2-O_{5}$ and MgO in cured leaf.

• Journal of Sensor Science and Technology
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• v.8 no.5
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• pp.414-420
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• 1999

The oxide sacrificial layer technology is one of the key technologies in surface micromachining. However, the commonly used aqueous HF solutions, including the $NH_4F$ buffered HF solutions (BHF), are known to attack the Al metal layers during the oxide sacrificial etch. A mixed $NH_4F$/HF/glycerine aqueous solution of 4:1:2 ratio is known to have the best etch selectivity between oxide and AI, but even this sacrificial etchant has a significant etch rate for AI. This paper reports an extensive experimental study on various concentration ratios for HF, $NH_4F$ and glycerine, and develops the optimal mixture ratio for sacrificial etching. At the $NH_4F$/HF/glycerine ratio of 2:1:4, the etch selectivity between PSG and Al improves by approximately 6 times over the previously known best selectivity, to a value of 7,700. At this condition, the measured etch rate of PSG film is approximately $2.1\;{\mu}m/min$, which is sufficiently fast. The developed sacrificial etchant allows the addition of a Al metal layer in surface micromachining, without the worry of Al layer erosion during sacrificial etch.

• Proceedings of the Korean Fiber Society Conference
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• 1990.06b
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• pp.36-37
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• 1990

In the past, facile dissolution of cellulose has been hampered by the lack of suitable nondegrading solvents. Recently, this problem has been solved in our laboratory by the discovery of an inexpensive, convenient solvent system, that is the mixture of $NH_3\;and\;NH_4SCN$, for cellulose. Also, the $cellulose/NH_3/NH_4SCN$ solution system has been found to form the anisotropic, i.e., liquid crystalline phase. It is believed that both the cholesterio and the nematic phase occur. This finding has prompted extensive on-going researoh on the formation of the liquid crystalline phase from an inexpensive natural source such as cellulose since the nematic phase is envisioned as an excellent precursor sources for products with desirable properties, for example, high modulus and high strength. This interest naturally leads to a desire to understand the theological properties of the nematic phase so that the transformation of the nematic phase to the solid state with desirable properties can be efficiently accomplished, ;From this point of view, the theological behavior of the $cellulose/NH3_/NH_4SCN$ system has been studied as a function of shear rate and shear stress over a wide range of solvent compositions, cellulose concentration, centrifugation and urea contents, Results indicate that the viscosity decreases with increasing shear rate. A marked shear thinning behavior and a quasi-Newtonian behavior were observed in the low shear rate region and in the high shear rate region, respectively for all solvent compositions. The $cellulose/NH_3/NH_4SCN$ solution system only exhibited the viscosity increase with increasing cellulose concentration and failed to show the viscosity drop generally observed at the point of incipience of liquid crystal formation, This may be due to the gel-like nature of the solution by the association of the rodlike molecules into bundles which may serve as crosslinking points giving the cellulose solution a network structure. Also, simply hydrogen bonding may be so restrictive of molecular mobility that a viscosity drop is blocked. In addition to the above results, yield stress and thixotropy were also observed in the $cellulose/NH_3/NB_4SCN$ solution system which are characteristics of liquid crystal and gel, The results of the effect of centrifugation on viscosity show that viscosity decreases by the application of centrifugation. This may be explained by the change of the piled polydomain structure to the dispersed polydomain structure due to the pressure gradient generated during centrifugation.ation.

• Journal of environmental and Sanitary engineering
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• v.20 no.4 s.58
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• pp.9-20
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• 2005

The purpose of the study was characteristics of secondary pollutants of $PM_{10}$ collected in pocheon between August 2002 and June 2003. The ambient concentrations of $PM_{10}$ mass, 9 water-soluble anions and cations, and 13 bulk composition trace elements were determined from filter samples collected by $PM_{10}$ high volume air sampler(UV-15H, Graseby-Anderson Co., USA). During this period average $PM_{10}$ mass concentration was $83.8{\mu}g/m^3(49.8{\mu}g/m^3\~111.6{\mu}g/m^3)$ in Pocheon. Mechanism for transformation of secondary pollutants by soluble ion components is divided into two categories; $NaNO_3$ type by the reaction of sea salt and $HNO_3$ in the atmosphere, and nitrate salt or phosphate salt type such as $(NH_4)_2SO_4,\;NH_4NaSO_4,\;and\;(NH_4)_2SO_4(2NH_4O_3)$.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.3
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• pp.282-286
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• 2016

This study was carried out to evaluate the effect of application of urea and combination of urea and pig manure compost (PMC) on the occurrence of and the recovery from ammonium ($NH_4{^+}$) toxicity in Chinese cabbage. To identify $NH_4{^+}$ toxicity of the crop four levels of urea at 0, 160, 320, and $480kg\;N\;ha^{-1}$ were applied, in addition, three levels of PMC at 10, 20, and $40M/T\;ha^{-1}$ was also applied with urea $320kg\;ha^{-1}$. For recovery $NH_4{^+}$ toxicity, six levels of sucrose were treated at the amount of 0, 600, 1,200, 1,800, 2,400, and $3,000kg\;C\;ha^{-1}$ at each level of combining treatments of urea and PMC. Our results showed that $NH_4{^+}$ toxicity was occurred at every urea application of $320kg\;N\;ha^{-1}$ regardless of PMC applied to the soils because $NH_4{^+}$ contents in the soils were more than $155mg\;kg^{-1}$ which was found to be the critical level to damage crop growth at 2 days after transplanting (DAT) in this experiment, the more sucrose was applied up to $1,800kg\;C\;ha^{-1}$ for the plants damaged by ammonium toxicity occurred at $320kg\;N\;ha^{-1}$, the greater extents recover the plants from the toxicity. PMC showed the similar effect with sucrose on recovering Chinese cabbage plants from $NH_4{^+}$ toxicity at 30 DAT.