• Korean Journal of Soil Science and Fertilizer
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• v.33 no.5
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• pp.356-360
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• 2000

This study was carried out to assess the neutralization ability of $NH_4{^+}$ and $Ca^{2+}$ on the acidity of rainwater in Korea. The rainwater was collected in Ansung area for six months from May to October in 1993, 1994, 1995, 1997, and 1998, respectively. Rainwater were analyzed for chemical composition and their theoretical pH values were calculated. As for the results, the distribution rates of rain at the pH 5.0~5.6 range were high. The equivalent ratio of $SO_4{^2-}/NO_3{^-}$ was decreased since 1994. Theoretical acidity which was calculated by-$log([H^+]+[NH_4{^+}]+[Ca^{2+}])$ was 5.0~12.6 times higher than measured acidity in Ansung area each monitoring year. The monthly difference between measured pH and theoretical pH was lower in July and August than any other month. $NH_4{^+}$ contributed more to the neutralization of rainwater acidity than $Ca^{2+}$. And the neutralization ratio of rainwater acidity by these two ions decreased during the years from 91.8% in 1993 to 88.7% in 1998.

• Journal of the Mineralogical Society of Korea
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• v.18 no.1
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• pp.11-17
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• 2005

Na-A zeolite were synthesized from melting slag of the incinerated ash by the alkaline activation processes. The experiments were performed in stainless steel vessels, with continuous stirring during the reaction periods. The silica-rich solution, a starting material, which was the waste of crystal growth factory, contains 5.7 wt% SiO₂ and 3.2 wt% Na₂O. And NaAlO₂ was made by the reaction of aluminium dross and NaOH solution and its molar ratios were Na₂O/Al₂O₃= 1.2 and H₂O/Na₂O=9. During the residence time of 7∼8 h at 80℃, the mixing of the silica-rich solution, NaAlO₂ and melting slag yields the production of homogeneous Na-A zeolite. The optimal reactant composition in molar ratio of Na₂O:Al₂O₃:SiO₂ was 1.3∼l.4 : 0.8∼0.9 : 2 and mixing ratio of solution and slag was 1/7∼10 (g/cc). Synthesized Na-A zeolite has cubic form uniformly and its size ranges about 1 ㎛. Ca/sup 2+/ ion exchange capacity of the Na-A was about 180∼210 meq/100g, corresponding approximately 80% to the commercial detergent builder.

• Applied Chemistry for Engineering
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• v.16 no.2
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• pp.250-256
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• 2005

Coating appearance is the most important problem in automotive industry. To increase the coating appearance quality, the corrosion resistance and the coating adhesion on metal substrates must be basically solved. The phosphating film made by the pretreatment of metal substrate is important factor to increase the coating adhesion. During the cathodic electrodeposition, the pH at the cathode surface increases up to about 12. In such a highly alkaline condition, the dissolution of metal substrate and phosphate film occurs. These phenomena result in the decrease of the bonding strength between the phosphating film and the substrate. Generally, the structure of zinc phosphating film is hopeite or phosphophyllite. It has been known that the phosphophyllite film contains better corrosion resistance and paint adhesion for hot water immersion test because of the decrease of dissolving amount of both metal substrate and phosphating film during the cathodic electrodeposition. It is found that the addition of Ni and Mn composition increase P-ratio and then can improve the paint adhesion on metal surface and the corrosion resistance.

• Journal of fish pathology
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• v.23 no.3
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• pp.335-342
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• 2010

In 2008, mass mortality was observed in paradise fish Macropodus opercularis which was imported from Indonesia. PCR of these fish found positive for megalocytivirus and Mycobacterium sp., while an unidentified virus was culture-isolated using CHSE-214 cells. In the present study, we investigated characterization of the unidentified virus and its pathogenicity to determine whether the virus was the causative agent of the mass mortality of paradise fish. The unidentified virus induced cytopathic effect (CPE) with syncytia in CHSE-214 and other fish cells, BF-2, GF, SSN-1, FSP and FFN. The virus was resistant against treatments with IUdR, chloroform, acidity at pH 3, basicity at pH 11 and high temperature at $56^{\circ}C$ for 3h. By electron microscopy, the viral particles were spherical having a double capsid structure with approximately 65 nm in external diameter. Viral genome was composed of at least 10-segmented RNA with sizes ranging from 0.7 kb to 3.6 kb. Based on these characters, this virus can be classified into family Reoviridae. This reovirus did not cause any mortality in an artificial experiment conducted by injecting the virus to paradise fish. This indicates that the reovirus is not only responsible for the mass mortality of paradise fish in 2008.

• Korean Journal of Food Science and Technology
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• v.34 no.4
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• pp.552-558
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• 2002

Polyphenol oxidase from Flammulina velutipes was purified and characterized. Purification of polyphenol oxidase was achieved by ammonium sulfate precipitation, Superdex G-200 gel filtration chromatography, Phenyl superose affinity chromatography, Mono-Q anion exchange chromatography and Superdex S-200 gel filtration chromatography on FPLC. After these purification steps specific activity of purified polyphenol oxidase increased to 199.1 units/mg. Polyphenol oxidase from F. velutipes was composed of a single polypeptide with molecular weight of about 40 kDa. Optimum pH and temperature for the enzyme reaction were found to be 6.0 and $25^{\circ}C$, respectively. The activity of the enzyme gradually decreased at acidic pH between 3 and 5, and the enzyme lost its activity at alkaline pH between 8 and 10. This enzyme exhibited high substrate specificity to o-diphenols. Km-values for L-DOPA and caffeic acid were found to be 3.97 mM and 1.78 mM, respectively. 2-mercaptoethanol, L-ascorbic acid, sodium bisulfite, EDTA and $Mg^{2+}$ inhibited the activity of pholyphenol oxidase and $Cu^{2+}$, $Fe^{2+}$, $Zn^{2+}$ and $Ni^{2+}$ increased enzyme activity. The activity of enzyme was well maintained at $-70^{\circ}C$ for over 4 months, and at $-20^{\circ}C$ for 1 months.

• Korean Journal of Breeding Science
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• v.40 no.3
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• pp.344-347
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• 2008

"Nunbora" is a new japonica rice cultivar developed from a cross between Iksan433 resistant to bacterial blight and Miyadamamochi, a waxy line. at Honam Agricultural Research Institute, NICS, RDA, in 2006. This cultivar is a short grain shape and about 118 days of growth duration from transplanting "Nunbora" to harvesting under Korean climatic conditions. The milled rice are snow white and glutinuous. This cultivar shows high resistant reactions to the bacterial blight pathogen race $K_1{\sim}K_3$ and blast respectively. The milled rice yield of "Nunbora" is about 5.34 MT/ha under the standard fertilizer level of the ordinary transplanting cultivation. "Nunbora" would be adaptable for in the middle plain, north middle-mountin plain and Honam plain, and Youngnam plain areas of Korea.

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.4
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• pp.413-418
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• 1985

Tobacco plant(8-leaf seedlings) were grown on water culture fertilized with different N sources ($NO_3-N$, $NH_4-N$, $NO_3+NH_4-N$) during 15 days. Daily uptake of nutrients and inorganic constituents in plants were investigated in relation to growth responses of them. 1. Nitrate-fed plant showed higher daily uptake of inorganic cations than those in other treatments, and reached about two times higher uptake of nitrogen and three times more uptake of cations (K, Ca, Mg). Potassium was preferentially uptaken at a very fast rate from the beginning after treatment. Also $NO_3-N$ tended to be taken up selectively by the plant from the mixture of nitrate and $NH_4-N$. 2. The initial pH (pH 6.0) of culture medium drastically changed into acid (pH 4.0) in the $NH_4-N$ medium, but into slightly higher (pH 6.4) in the nitrate when measured after exposure of 24 hours. The mixture also tended to show an acidity but much weaker than $NH_4-N$ solution. 3. Nitrate-fed plant had a normal growth pattern but $NH_4-N$ fed plant almost stopped growing. Those plants containing both nitrate and ammonium N were also showed very poor growth.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.1
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• pp.67-71
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• 1998

This study was carried out to granulate artificial zeolite powder that remove ammonium nitrogen and phosphorous simultaneously in wastewater treatment. Optimum water content was required for 30 percent volume to granulate artificial zeolite with 1.7mm diameter and 1~2cm length using granulator. Portland cement could remove much $NH_4{^+}$ and $PO_4{^{3-}}$ from the wastewater than other binding materials. Mixed 33, 25. 20. 16 percent of portland cement to artificial zeolite powder(v/v), cation exchange capacity of the granulars were 66.5, 81.4, 126.8, $151.2cmol^+kg^{-1}$ and hardness of that were 176.1, 24.4, 4.1, $0.4kg\;cm^{-2}$, respectively. Content of portland cement in the granular were related with removal of $PO_4{^{3-}}$ positively and that of $NH_4{^+}$ negatively. Shaked 1g of the granulars that made of portland cement 33 percent with 40ml synthetic wastewater containing $NH_4{^+}$ $1545mgl^{-1}$ and $PO_4{^{3-}}$ $417mgl^{-1}$, 99.4 percent of $NH_4{^+}$ and 90.3 percent of $PO_4{^{3-}}$ were removed simultaneously after 48 hours shaking. The longer shaking, the more $NH_4{^+}$ and $PO_4{^{3-}}$were removed. The artificial zeolite granular had both micropore and macropore that could be useful in the wastewater purification.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.2
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• pp.145-153
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• 1995

Effects of lime application levels(0, 10, 50, 100, and 300kg/10a) on three alfalfa cultivars(Dekalb brand 120, Pike, Pioneer brand 5929) were analyaed with respect to the growth, dry matter yield, and inorganic composition of the plants at three cutting periods. Major chemical properties of the soils were also analyzed. Response of the plant height to the lime application level was variable among the cultivars, showing the order of 50>100>300>10>0kg/10a in Dekalb brand 120, 50>100>10>300>0kg/10a in Pike, and 10>50>300>0>100kg/10a in Pioneer brand 5929. The order of dry matter yield response to the lime application level was 50>300>100>10>0kg/10a in Dekalb brand 120, 50>10>300>100>0kg/10a in Pike, and 50>100>10>0>300kg/10a in Pioneer brand 5929. Total dry matter yields at 50kg/10a lime application level were higher than those at any other levels in all the cultivars. Neither a specific pattern nor a significant change in inorganic composition of the plant was found for the lime application levels and cutting times, Soil chemical properties and composition remained with little change after the experiment except the soil pH, which was increased with the lime application level.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.1
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• pp.71-76
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• 2007

We investigated the effects of solution pH on swelling characteristics and relevant hydraulic conductivity of different particle sizes of Na-bentonite which have significantly high swelling capacity. The results showed that the time taken to reach the maximum swelling indexes for all pH levels ranged from 84 hours and 156 hours for pH 6.5 or above by NaOH and pH 3.5 by HCl, respectively. The maximum swelling index slightly increased with increasing particle size, while the maximum swelling indexes were less or approximately half of that of the indigenous Na-bentonite. The changes in swelling indexes before and after solution treatment were distinctive in acidic condition, especially in pH 3.5 by HCl while there were not much differences in alkali condition. For hydraulic conductivities of fully swelled Na-bentonite in a given solution pH, elution did not occur under pressure below 1 bar. But elution started as the pressure was raised to 1.5 bars or above after 500 seconds. The stabilized hydraulic conductivities observed from 1.5, 3.0, and 5.0 bars ranged from $7{\times}10^{-3}cm\;day^{-1}$ to $6{\times}10^{-3}cm\;day^{-1}$, indicating that the hydraulic conductivities were slightly higher in acidic condition than that of normal condition.