• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.1
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• pp.90-99
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• 2015

This study examined dynamic and characteristics and chloride penetration of concrete mixed with large amount of FA and BFS, which are considered for positive application to construction fields with purpose of long-tern durability of concrete structures. As a result of strength test on FA and BFS, FA concrete showed higher increase of strength compared to OPC, when FA4000 and FA5000 were mixed 30%, respectively. For BFS concrete, those mixed with 30% and 50% of BFS8000, respectively, showed higher or equivalent strength compare to OPC. As a result of test of chloride penetration on FA and BFS, diffusion coefficients of concrete mixed with 30% FA4000 and FA5000, respectively, showed to restrain average 6.5% of diffusion coefficient compared to OPC. And in case of BFS concrete, those mixed with BFS6000 and BFS8000, restrained diffusion of chloride ions 253% and 336%, respectively, compared to OPC. Therefore, Mixing 50% of BFS was most efficient in order to maximize restraint of chloride penetration according to metathesis of large amount. For relation between compression strength and diffusion coefficient of FA and BFS concrete, as strength increased, diffusion coefficient decreased. In this study, when mixing FA and BFS to concrete for long-run durability and restraint against chloride penetration, for FA, mixing it to concrete with less or equivalent 30% of replacement rate was most efficient. And for BFS, as fineness was higher and mixing it to concrete with less or equivalent 50% of replacement rate, there were results of higher strength compared to OPC and more efficient restraint of chloride ions.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.2
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• pp.125-131
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• 2009

Reductive dechlorination of polychlorinated dibenzo-p-dioxins (PCDDs) and its toxicity change were predicted by the linear free energy relationship (LFER) model to assess the zero-valent iron (ZVI) and anaerobic dechlorinating bacteria (ADB) as electron donors in PCDDs dechlorination. Reductive dechlorination of PCDDs involves 256 reactions linking 76 congeners with highly variable toxicities, so is challenging to assess the overall effect of this process on the environmental impact of PCDD contamination. The Gibbs free energies of PCDDs in aqueous solution were updated to density functional theory (DFT) calculation level from thermodynamic results of literatures. All of dechlorination kinetics of PCDDs was evaluated from the linear correlation between the experimental dechlorination kinetics of PCDDs and the calculated thermodynamics of PCDDs. As a result, it was predicted that over 100 years would be taken for the complete dechlorination of octachlorinated dibenzo-p-dioxin (OCDD) to non-chlorinated compound (dibenzo-p-dioxin, DD), and the toxic equivalent quantity (TEQ) of PCDDs could increase to 10 times larger from initial TEQ with the dechlorination process. The results imply that the single reductive dechlorination using ZVI or ADB is not suitable for the treatment strategy of PCDDs contaminated soil, sediment and fly ash. This LFER approach is applicable for the prediction of dechlorination process for organohalogen compounds and for the assessment of electron donating system for treatment strategies.

• Journal of the Korean Ceramic Society
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• v.38 no.11
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• pp.1023-1029
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• 2001

Hexagonal ferrite $Co_2$Z(B $a_3$ $Co_2$F $e_{24}$ $O_{41}$ ) was prepared by various coprecipitation-oxidation methods. The formation of $Co_2$Z was studied in order to determine the optimal method. The $Co_2$Z composition hydroxides were prepared with the different oxidation and precipitation from the aqueous solution of $Ba^{2+}$, $Co^{2+}$ and F $e^{2+}$ chloride mixture. The coprecipitates were heat-treated at various temperatures, and their formation phases and microstructures were investigated from the analyses of DTA/TGA, powder XRD and SEM. The $Co_2$Z phase was observed in the case where the precursor will have the amorphous like oxyhydoxide($\delta$-FeOOH), and formed from $Ba_3$F $e_{32}$ $O_{51}$ , BaF $e_{12}$ $O_{19}$ (M-type) and $Ba_2$ $Co_2$F $e_{12}$ $O_{22}$ (Y-type). The $Co_2$Z was synthesized by the heat-treatment of the coprecipitate, which was prepared from the precipitation after oxidizing the chloride mixed solution, above 110$0^{\circ}C$.EX>.

• Journal of the Korean Chemical Society
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• v.17 no.5
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• pp.346-352
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• 1973

The quantitative separations of a mixture containing equal amounts of each cation such as Mn(Ⅱ), Cr(Ⅲ), V(Ⅴ), Cu(Ⅱ), Ni(Ⅱ), Co(Ⅱ), and Fe(Ⅲ) are carried out by the elution through $35cm{\times}3.14cm^2$ column of cation exchange resin, $Dowex 50w{\times}12$. The eluents are a mixture of 0.6 M sodium chloride and 0.1 M sodium tartrate (pH = 2.00 and 4.50) for Fe(Ⅲ), V(Ⅴ), Cu(Ⅱ), Ni(Ⅱ) and Co(Ⅱ), and a mixture of 3 M sodium chloride and 0.1 M sodium tartrate (pH = 4.50) or a mixture of 0.7 M sodium chloride and 0.5 M sodium oxalate (pH = 4.50 and 5.00) for Mn(Ⅱ) and Cr(Ⅲ). The subsidiary cations in a standard iron mixture such as V(Ⅴ), Cu(Ⅱ), Ni(Ⅱ), Mn(Ⅱ) and Cr(Ⅲ) are separated together from the large amount of Fe(Ⅲ) through $15cm{\times}3.14cm^2$ column of the resin, $Dowex 1{\times}8$, by elution with the eluent of 4.0 M hydrochloric acid. A small amount of Fe(Ⅲ), however, is eluted together with Cu(Ⅱ). V(Ⅴ), Ni(Ⅱ), Mn(Ⅱ) and Cr(Ⅲ) eluted together are separated quantitatively through $10cm{\times}3.14cm^2$ column of the resin,$Dowex 50w{\times}12$. Cu (Ⅱ) and a small amount of Fe(Ⅲ) are separated quantitatively through $10cm{\times}3.14cm^2$ column of the resin, $Dowex 50w{\times}12$, by the elution with a mixture of 0.6 M sodium chloride and 0.1 M sodium tartrate (pH = 2.00 and 4.50) as an eluent. By the conditions obtained in the separations of the standard iron mixture, Fe(Ⅲ) and all of the subsidiary cations in steel are quantitatively separated.

• Economic and Environmental Geology
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• v.11 no.3
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• pp.89-98
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• 1978

Mineralogy, beneficiation, and processes of titanium ores are reviewed from petrographic viewpoints. The most important titanium minerals are ilmenite ($FeTiO_3$) and rutile ($TiO_2$). Ilmenite will play major role :for raw material, because rutile are rapidly diminishing. Thus, there is a need to develope a successful process for producing high grade Ti02 from ilmenite. Commercial, as well as R and D processes to treat more abundant ilmenite ores fall in three general classess: 1. Iron in ilmenite is partially or completely reduced and separated either physically or chemically. 2. Iron is reduced to ferrous state and chemically leached away from the titanium. 3. Ore is treated to make chlorides either selectively or with subsequent separation and purification of $TiC_4$. Routes and efficiencies of these process technologies are primarily influenced by the particular ore deposit to be mined and secondly by environmental considerations. One deposit parameters which influence ilmenite process technologies are: 1. Complexity of microtextures of ilmenite intergrown with Fe-oxide minerals. 2. Composition of concentrates; ilmenites contain minor amounts of substituted Mg, Mn, and V. These elements plus iron and gangue minerals can cause difficulties to complete reactions, substantial acid consumption, difficulties of removing waste solids, and waste disposal problems. Major contributions to be made by petrologists for process optimization are: characterization and interpretation of compositional and physical changes of raw materials and solids derived from process streams. These informations can play significant role in selecting and improving process steps for titania production.

• Resources Recycling
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• v.27 no.6
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• pp.53-58
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• 2018

Solvent extraction of Li(I) from weak HCl solution was investigated by the mixture of TBP/MIBK with other neutral extractants such as Cyanex 923, TOPO and TOP. The TBP/MIBK organic phase was loaded with 0.1 M $FeCl_3$ at different HCl concentrations (1-9 M). Extraction of Li(I) from weak HCl solution is related to the stability of $FeCl_3$ in the organic mixture. As HCl concentration increased in preparing the loaded TBP phase, the stripping percentage of Fe(III) during the extraction of Li(I) became reduced and thus Li(I) could be extracted by ion exchange reaction with hydrogen ion in the organic. The concentration of TBP in the extractant mixture affected the stability of $FeCl_3$. Compared to TBP, Fe(III) was easily stripped from the loaded MIBK and thus no Li(I) was extracted by the mixture with MIBK. The nature of neutral extractant with TBP/MIBK showed little difference in the extraction of Li(I) and stripping of Fe(III).

• Journal of the Korean Institute of Gas
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• v.4 no.2 s.10
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• pp.27-32
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• 2000

In this study, $Mn_3O_4$ was synthesized by the different equivalent ratios using solution of $MnCL_2 {\cdot} 4H_2O$ and NaOH. We have investigated the crystal structure and surface area by XRD, BET Method, studied on the decompositon and adsorption of carbon dioxide with synthesized $Mn_3O_4$. As the results, we surveyed that main peak was $Mn_3O_4$, some Peaks were $MnO_2$ and $Mn_5O_8$ The specific surface area was ranged from $13.92m^2/g$ to $32.33m^2/g$. The decomposition of $CO_2$ was observed by the differential equivalent ratios at $450^{\circ}C$. $CO_2$ was well decomposed at equivalent ratio of 0.75. The amount of chemisorption of $CO_2$ was ranged from 2.885 to 19.628cc/g. Optimal equivalent ratio was 1.00 for the chemisorption of $CO_2$.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.2
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• pp.128-134
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• 1990

Croping pattern, fertilizer application, Soil chemical characteristics, plant nutritional condition and growth status were investigated in three major vinyl house farms near Yesan. Croping pattern changed from tomato to pumpkin due to tomato diseases such as wilting and blossom-end rot. Wilting seemed to be closely related with high EC, nitrogen and root cyst nematodes. Calcium deficiency seemed to be due to high potassium, EC in soil and high uptake of iron. Chinese cabbages in summer showed poor growth (80% inhibition) due to high EC(1.8mmho/cm) and easily got wenny root disease that might due to high phosphorus (1055ppm) in soil. Summer radish showed poor growth (50% inhibition) due to high EC(1.6mmho/cm), K and Mg resulting in base imbalance. Farmers used 5 kinds of compound fertilizer as basal application and one without P for top dressing. Urea and KCL were used for top dressing. Heavy application of livestock manure and chemical fertilizer for every crop made eutrophic even in subsoil.

• Polymer(Korea)
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• v.37 no.3
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• pp.255-261
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• 2013

This paper introduced a new preparation method of a composite rubber by mixing BR (butadiene rubber) and CIIR (chloro-isobutyl rubber) for the purpose of improving frictional property of BR. Since BR has high abrasion and low frictional properties, its frictional property needs to be enhanced in order to be used as an outsole of a sport shoe. Such enhancement was difficult to achieve by simple blending of CIIR. In here, CIIR was added into BR matrix after CIIR was pre-crosslinked for a time period, and both high frictional and high abrasion resistance properties were achieved. Our experiments showed that the composite rubber blend of 60% of BR and 40% of pre-crosslinked CIIR had desired BR's frictional and abrasion resistance properties for sport shoes.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.5
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• pp.570-575
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• 1993

Antioxidative characteristics of melanoidin related products(MRPs) fractionated from fermented soybean sauce were studied during the oxidation process of model systems. MRPs were prepared from soybean sauce fermented for 6 months after inoculation Aspergillus oryzae by the fractionation through the Sephadex G-10 column and the freeze drying of collected fractions. MRPs inhibited the formation of peroxides during the oxidation of linoleic acids mixture in ethanolic phosphate buffer solution at $50^{\circ}C$ with the increasing tendency by their concentration in reaction systems. MRPs had hydrogen doner properties during the reaction with ${\alpha},\;{\alpha}'-diphenyl-{\beta}-picrylhydrazyl$ and also MRPs inhibited the iron and lipoxygenase catalytic oxidation. MRPs were found to be fairly stable with no loss of antioxidative effect after storage at $50^{\circ}C$ for 15days.