• Journal of Korean Society on Water Environment
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• v.23 no.3
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• pp.371-376
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• 2007

The features of precipitating reaction of fluorine have been examined under several aquatic conditions by employing calcium ion as a precipitant. Based on MINTEQ program, fluorine was found to exist in the forms of $H_2F_2$ and HF in strong acidic environment and change into $F^-$ with increasing pH. In the experimental condition, the precipitating reaction of fluorine progressed rapidly within a few minutes after the reaction started and reached its equilibrium in 10 minutes. As the addition of precipitant was increased, removal of fluorine by the formation of precipitate was promoted and its was also enhanced by the rise of pH. The precipitating reaction of fluorine was impeded when its initial concentration was low and X-ray analysis showed that the crystalline structure of precipitate was mainly $CaF_2$ with partly NaF. Coexisting phosphate in solution influenced the fluorine removal by impeding the precipitate formation and similar effect was found when metallic ion such as $Zn^{2+}$ was present with fluorine.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.3
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• pp.67-73
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• 2010

Pine (Pinus densiflora) and aspen (Populus euramericana) wood meals were treated with ozone at various time schedule in acidic condition. The lignin contents and surface area of the ozone treated wood meals were determined and the enzymatic hydrolysis rate of ozonated wood meals was evaluated. The feasibility of enzymatic hydrolysis of the ozone treated wood meal was obviously influenced with the degree of delignification. After ozone treatment of wood meal for 10min, total pore volume were slightly increased in the surface of wood meal. When wood meals were treated with ozone longer than 10min, few change in the pore volume was observed. However, the area of over $50{\AA}$ of pore size is increased with ozonation time. As a conclusion, the rate of enzymatic hydrolysis of wood is more effective with the pore size distribution than the total pore volume.

• Textile Coloration and Finishing
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• v.30 no.2
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• pp.150-157
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• 2018

The purpose of this study is to investigate the proper dyeing condition, color fastness and functionality of silk fabrics dyed with Zizania latifolia Turcz. FT-IR spectrum analysis suggests that colorants of Zizania latifolia Turcz. are tannins. The dyeing of the silk fabrics using Zizania latifolia Turcz. was very good even without pretreatment or mordanting treatment. Optimal dyeing conditions of silk fabrics were colorant concentration of 200%(o.w.f.), dyeing temperature of $100^{\circ}C$, dyeing time of 60 minutes and dyebath pH of 5.5. Color fastness of dyed silk fabrics to washing, rubbing, perspiration and light was 4~4-5, 5, 4~4-5(acidic), 4-5(alkaline) and 2 respectively. UV protection rate and deodorization rate of silk fabrics dyed with Zizania latifolia Turcz. were improved. Reduction rate(Staphyloccus aureus) of silk fabrics was excellent at 98.3%. As a result, it was confirmed that the Zizania latifolia Turcz. could be used as an eco-friendly functional natural dye.

• Economic and Environmental Geology
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• v.29 no.2
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• pp.159-170
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• 1996

The gold-silver deposits of the Nakcheon, Eunchi and Jungbong mine in the northern Taebagsan mining district are composed of fissure fil1ing veins emplaced in Precambrian meta-sediments and Jungbongsan granite. Based on the changes of ore texture and mineralogy, ore mineral chemistry, fluid inclusion and mineralizing condition, a regional zoning is recognized from the Nakcheon to the Eunchi and Jungbong ore deposits, and this trend of zoning is also recognized by stable isotope compositions. Stable isotope compositions show that the source of su1fur and carbon is mainly igneous origin, and the water of ore fluid in the Nakcheon ore deposits is mainly magmatic origin but much of meteoric water is involved in ore fluid of the Eunchi and Jungbong ore deposits. The ore deposits of study area is polymetallic meso to epithermal type genetically related to the acidic igneous pluton. Due to the differntial erosion level and mineralized depth, each ore deposits has a slightly different characteristic of mineralization; The Nakcheon ore deposits belong to meso-epithermal type, but the Eunchi and Jungbong ore deposits belong to epithermal type.

• Journal of Pharmaceutical Investigation
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• v.40 no.3
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• pp.155-160
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• 2010

A gas chromatographic-mass spectrometric (GC-MS) method was developed for the simultaneous determination of valproic acid (VPA) and its toxic metabolites, 4-ene-VPA and 2,4-diene-VPA in rat plasma. Extraction was performed in weak acidic condition (pH 5.2) to avoid degradation of 4-ene-VPA and 2,4-diene-VPA. The recoveries for 4-ene-VPA and 2,4-diene-VPA were more than 70% and that for VPA was 33-42%. R value for each compounds exceeded 0.998 in calibration curve during all the analysis. Accuracy and precision ranged from 88.3 to 113.2% and from 2.16 to 14.2%, respectively The method was successfully applied to monitor plasma concentrations of VPA, 4-ene-VPA and 2,4-diene-VPA after intravenous administration of VPA at the dose of 100 mg/kg, suggesting that these toxic metabolites may involved in the hepatotoxicity induced by VPA.

• Journal of the Korean Graphic Arts Communication Society
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• v.15 no.1
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• pp.31-40
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• 1997

The objectives of color reproduction in printing, photography, and digital hard-copy is an important problem. The Color is obsorved differently from illumination an obsorvation condition, and varied according to individual taste. Generally, the color reproduction system is designed with colorimetric color reproduction method. But the color gamut of the color reproduction system is different each other and the one device has nonlinear relationalship between the other. By these reason, to predict the reproduced color based on linear color transform method is difficult. Some methods of non-linear color transform by neural network was proposed. These method was theoretical useful and valid to transform from CIE color to device color. But more studies were needed to realize the non-linear color transform system. In this paper, we described a method to realize the non-linear color transform system by neural network. The optimum structure of the non-linear color transform system was found out. The structure of descrived system has four layer( input, output and two hidden layers.) Input and output layer have 3 units, and a hidden layer has 27 units. We trained 216 color-samples, and estimated the realized color transform system by 1115 color-samples. The average color difference between original color samples and transformed color samples was 2.54.

• Journal of Applied Biological Chemistry
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• v.49 no.4
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• pp.157-161
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• 2006

The performance of abiotic degradation of oxadiazon was investigated by applying zerovalent iron(ZVI), potassium permanganate($KMnO_4$) and titanium dioxide($TiO_2$) in the contaminated water. Experimental conditions allowed the disappearance of oxadiazon in the abiotic system. The degradation of this herbicide was monitored in buffer solutions having pH 3, 5 and 7 in the presence of iron powder in which the maximum degradation rate was achieved at acidic condition(pH 3) by 2% of ZVI treatment. The oxidative degradation of oxadiazon was observed in aqueous solution by $KMnO_4$ at pH 3, 7 and 10 in which the highest disappearance rate was found at neutral pH when treated with 2% of $KMnO_4$. The catalytic degradation of oxadiazon in $TiO_2$ suspension was obtained under dark and UV irradiation conditions. UV irradiation enhanced the degradation of oxadiazon in aquatic system in the presence of $TiO_2$. Conclusively, the remediation strategy using these abiotic reagents could be applied to remove oxadiazon from the contaminated water.

• Journal of Microbiology and Biotechnology
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• v.7 no.3
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• pp.167-173
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• 1997

Everted membrane vesicles of Helicobacter pylori were prepared and the membrane-resided ATPases were characterized. For comparison, Escherichia coli membrane ATPases and hog gastric mucosal H,K-ATPase were employed. ATPase assay revealed that the composite enzyme pool was relatively low in specific activities, below 1/10 times than that found in E. coli. According to their inhibitory specificities, most of the ATPase pool appeared to belong to the P-type ATPase, sensitive to vanadate but not to azide. The enzyme pool was extraordinarily resistant against treatment by N,N'-dicyclohexylcarbodiimide (DCCD). Certain monovalent cations, e.g., $K^+$ or $NH_4^{+}$ stimulated the whole enzyme pool only in the presence of $Mg^{2+}$. On the contrary, $Ni^{2+}$ and $Zn^{2+}$ increased enzyme activity rather effectively without the aid of $Mg^{2+}$. Under a defined condition employed, H. pylori cells could retain the membrane ATPase pool to the extent of $17{\%}$ at pH 3.2. Moreover, its activity was most stable in acidic conditions (pH 5.4-6.4). However, cytoplasmic or peripheral ATPase pools were hardly detected under acidity (below pH 4.6).

• Journal of Microbiology and Biotechnology
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• v.20 no.2
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• pp.294-300
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• 2010

The Iro protein is a member of the HiPIP family with the [$Fe_4S_4$] cluster for electron transfer. Many reports proposed that the conserved aromatic residues might be responsible for the stability of the iron-sulfur cluster in HiPIP. In this study, Tyr10 was found to be a critical residue for the stability of the [$Fe_4S_4$] cluster, according to site-directed mutagenesis results. Tyr10, Phe26, and Phe48 were essential for the stability of the [$Fe_4S_4$] cluster under acidic condition. Trp44 was not involved in the stability of the [$Fe_4S_4$] cluster. Molecular structure modeling for the mutant Tyr10 proteins revealed that the aromatic group of Tyr10 may form a hydrophobic barrier to protect the [$Fe_4S_4$] cluster from solvent.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.171-176
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• 2004

Electro chemical corrosion tests were conducted on two structural steels, SS400 and SM490A, in various solutions with different pH values, All materials showed typical active corrosion behaviors in the solutions, and corrosion potential and current density were measured from the slopes obtained from the Tafel curves using linear polarization method. Corrosion potential increased in the acidic region and then decreased depending on the pH values of the solutions. All materials showed the fast corrosion rate in artificial acid rain(pH=4.7), but the slower corrosion rate was observed in NaOH solution(pH=12.0) for SS400 and in distilled water(pH=7.0) for SM490A, respectively, which is thought to come from the difference in chemical composition of two alloys. Generally homogeneous corrosion occurred in acid rain condition, and almost no corrosion was observed in distilled water in both alloys. NaOH solution produced more corrosion than distilled water, and more corrosion had progressed in SS400 than in SM490A in $3.5\%$ NaCl solution.