• Korean Journal of Environmental Biology
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• v.24 no.1 s.61
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• pp.38-45
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• 2006

Ecological characteristics of microbial populations inhabiting heavy metal polluted soil were investigated. The samples were collected from 293 sites around an factory and industry at Gyeoungsangbuk-do. We measured the contents of seven heavy metal elements (Cd, Cu, As, Hg, Pb, $Cr^{6+}$, CN), seven sites have been seriously contaminated by mercury and chrome. A quantitative evaluation of microbial populations in mercury and chrome contaminated soil was examined by using plate count method. Bacterial numbers in polluted soil samples ranged from $7.4X10^5\;to\;9.3X10^7\;cfu\;g^{-1}$, about $10\sim100$ fold less than the count for the unpolluted soil. Moulds were not detected in chrome polluted soil. The log values of actinomycetes of each contaminated soil samples were log ranged from 6.18 to 7.52. The ratio of actinomycetes was similar to unpolluted soil. The investigation showed actinomycetes to be the major microbial population inhabiting the mercury and chrome polluted soil. Thirty-one isolates among the total isolates were examined for antibacterial activity. These isolates were identified based on a phylogenetic analysis using 16S rRNA gene nucleotide sequences, they were categorized in three major phylogenetic groups, belong to the Streptomyces (6 strains), Saccharopolyspora (3 strains), Nocardiodes (1 strain). On the phylogenetic tree, the clade consisting of five isolates were distantly related to all of the established Streptomycetes genera, indicating the possibility as members of new species.

• Economic and Environmental Geology
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• v.25 no.3
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• pp.233-243
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• 1992

Ore mineralization of the Hwanghak copper deposit in the Ogsan area occurred in three stages of quartz (stage I and II) and calcite (stage III) veining along fissures in Early Cretaceous sedimentary rocks. Ore minerals are pyrite, pyrrhotite, chalcopyrite (dominant), sphalerite, hematite, galena, and Ag-, Pb-, and Bi-sulfosalts. These were deposited during the first stage at temperatures between $370^{\circ}C$ and < $200^{\circ}C$ from fluids with salinities between 0.5 and 7.6 equiv. wt. % NaCl. There is evidence of boiling and this suggests pressures of less than 180 bars during the first stage. Equilibrium thermodynamic interpretation accompanying with mineral paragenesis and fluid inclusion data indicates that copper precipitation in the hydrothermal system occurred due to cooling and changing in chemical conditions ($fs_2$, $fo_2$, pH). Gradual temperature decrease from $350^{\circ}$ to $250^{\circ}C$ of ore fluids by boiling and mixing with less-evolved meteoric waters mainly led to copper deposition through destabilization of copper chloride complexes. Sulfur isotope values of sulfide minerals decrease systematically with paragenetic time from calculated ${\delta}^{34}S_{H_2S}$ values of 8.2 to 4.7‰. These values, together with the observed change from sulfide-only to sulfide-hematite assemblages and fluid inclusion data, suggest progressively more oxidizing conditions, with a corresponding increase of the $sulfate/H_2S$ ratio of hydrothermal fluids. Measured and calculated hydrogen and oxygen isotope valutls of ore-forming fluids suggest meteoric water dominance, approaching unexchanged meteoric water values.

• Korean Journal of Food Science and Technology
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• v.27 no.5
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• pp.819-825
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• 1995

Two sweet potato CV.(Ipomoea batatas) were examined, i.e. purple flesh sweet potato(PSP) and light yellow flesh sweet potato(LYSP) which varied in degree of sweetness. On a fresh weight basis, nitrogen free extract in cultivars ranged from $25.73{\sim}26.24%$ and PSP contained more crude fat than LYSP. Total amino acids of PSP and LYSP were 5676.57mg% and 4550.86mg%, respectively. Aspartic acid, serine, alanine and valine were the major components in sweet potatoes. Sulfur-containing amino acids are the first limiting amino acid in PSP. The major fatty acids in PSP and LYSP analyzed by GC were palmitic acid, linoleic acid. The content of the saturated fatty acid was less than that of the unsaturated fatty acid. Carbohydrate contents were $75.43{\sim}79.10%$ and neutral sugars contents were $67.22{\sim}64.85%$(dry wt). Two sweet potato CV. contained the most glucose of all neutral sugars. PSP contained 11.88% for uronic acid, 59.42% for starch. Free sugars of PSP(0.82%) was much less than that of LYSP(2.53%). The contents of thiamin, riboflavin and niacin were similar, and the ascorbic acid contents in PSP and LYSP were 63.4mg% and 48.7mg%(dry wt), respectively. Comparing the mineral content in PSP, K was the greatest element in concentration followed by mg, Ca, Na. The total dietary fiber(TDF) value was 13.43% in PSP, 9.79% in LYSP respectively. The ratio of soluble dietary fiber(SDF) content and insoluble dietary fiber(IDF) content to TDF content for PSP were 57.6%, 42.4%, respectively.

• Clean Technology
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• v.23 no.2
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• pp.158-162
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• 2017

$FeCl_3$ solution has been used as an etchant for metal etching such as Fe, Cu, Al and Ni. In the etching process, $Fe^{3+}$ is reduced to $Fe^{2+}$ and the etching efficiency is decreased. Waste $FeCl_3$ etchant has environmental, economic problems and thus the regeneration of the etching solution has been required. In this study, HCl was mixed with the $FeCl_2$ solution and then, $H_2O_2$, $NaClO_3$ were added into the mixed solution to oxidize the $Fe^{2+}$. During the oxidation process, oxidation-reduction potential (ORP) was measured and the relationship between ORP and oxidation ratio was investigated. The ORP is increased with increasing the concentration of $H_2O_2$ and $NaClO_3$, and then the ORP is decreased with oxidation progress. Such a behavior was in good agreement with Nernst's equation. Also, the oxidation efficiency was about 99% when a sufficient amount of HCl and $H_2O_2$, $NaClO_3$ were added.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.813-818
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• 2008

Various additives were added in small amounts on Ni/YSZ anode of SOFC (solid oxide fuel cell) in order to improve reactivity and to inhibit deactivation due to coke deposition during methane reforming using a low mole ratio steam ($H_2O/CH_4=1.5$) at $800^{\circ}C$. Ni/YSZ catalysts added with various perovskites did not show any improvement but exhibited a gradual decrease in the methane conversion. K-doped Ni/YSZ showed a steady increase and maintenance of the conversion up to 42 hours, after which there was an abrupt deactivation of catalyst owing to potassium loss by volatilization. Addition of 5% of $K_2Ti_2O_5$ on Ni/YSZ showed a stable maintenance of the conversion without K loss, and was able to prevent coke formation during a long time operation. Deactivation of catalyst during the reaction was mainly caused by the accumulation of graphidic carbon on the catalyst surface.

• Journal of Environmental Science International
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• v.2 no.1
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• pp.61-72
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• 1993

Result of this study indicate that two criteria must be met in order to have effective macrocycle-mediated transport in these emulsionsystem. First, one must effective extraction of the post transition metals, $Cd^{2+}$. $Pb^{2+}$ and $Hg^{2+}$ , into toluene membrane. The effectiveness of this extraction is greatest if log K values for the metal-macrocycle interaction is large. Second, the ratio of the log K values for the metal ion-receiving phase to the metal ion-macrocycle interaction must be large enough to ensure quantitative stripping of the metal ion at the toluene phase interface. Control of the first step can be obtained by appropriate selection of macrocycle donor atom, substituents, and cavity radius. The second step can be controlled by selecting the proper complexing agent for inclusion in the receiving phase. The order of the transport, when using the several $A^-$ species such as $SCN^-$, $1^-$, $Br^-$ and $Cl^-$ is the order of the changing degree of solvation for $A^-$ and the transport of the metals is also affected by the control of concentration for receiving species because of solubility-differences. In this study, we can seperate each single metal ion from the mixture of $Cd^{2+}$, $Pb^{2+}$, and $Hg^{2+}$ ions by using the toluene membranes controlled by optimized conditions. Transport of the single metal is also very good, and alkaline and alkaline earth metals as interferences ions did not affect the seperation of the metals in this macrocycle-liquid membrances but transition metal ions were partially affected as interferences for the post transition metal ions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.241-241
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• 2007

We fabricated SmBCO coated conductors(CCs) on IBAD-MgO templates using co-evaporation method. IBAD-MgO templates consist of PLD-LMO/epi-MgO/IBAD-MgO/Ni-alloy and showed good in-plane texture of below FWHM 7 degree. Evaporation rates of Sm, Ba, and Cu were precisely controlled to get the optimum composition ratio after deposition process. To optimize the oxygen partial pressure of reaction region, wide range of the partial pressure was investigated from 1 mTorr to 15 mTorr. By reducing the oxygen partial pressure to 5mTorr, (103)grains in SmBCO layer have been increased. On the other hand, there were only (001)grains in SmBCO layer deposited at 15 mTorr $O_2$. Deposition temperature was also investigated from $600^{\circ}C\;to\;800^{\circ}C$ to make high Ic SmBCO CCs. SmBCO on IBAD MgO template showed that the Ic increased gradually at higher growth temperature to $800^{\circ}C$, which the highest Jc and Ic is $2.6\;MA/cm^2$ and 500 A/cm-w., respectively.

• Journal of the Korean Electrochemical Society
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• v.22 no.4
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• pp.155-163
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• 2019

Mixture electrodes of a graphite having a good cycle performance and a silicon monoxide (SiO) having a high capacity are fabricated and their cycle performances are evaluated as negative electrodes for lithium-ion batteries. The electrode prepared by mixing the natural graphite and carbon-coated SiO in a mass ratio of 9:1 shows a reversible capacity of $480mAh\;g^{-1}$, 33% higher than that of graphite. However, the capacity deteriorates continuously upon cycling due to the volume change of silicon monoxide. In this study, the factors that can improve the cycle performance have been discussed through the change in the configurations of the electrode and the electrolyte. The electrode using the carboxymethyl cellulose (CMC) binder shows the best cycle performance compared to the conventional binders. The electrode sing the CMC and styrene-butadiene rubber (SBR) binder not only has almost the similar cycle characteristics with the electrode using the CMC binder but also has the better rate capability. When the fluoroethylene carbonate (FEC) is used as an electrolyte additive, the cycle life is improved. However, the electrolyte with 5 wt% of FEC is appropriate because the rate capability decreases when the content of FEC is increased to 10 wt%. In addition, when the mass loading of the electrode is lowered, the cycle performance is greatly improved. Also, enhanced cycle performance is achieved using the roughened Cu current collector polished by abrasive paper.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.1
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• pp.39-45
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• 1998

As a basic research for developing a sludge application technique in forestry, this study was conducted to investigage a reasonable amount and period of sludge to be applied onto forest nursery of Acer palmatum Thunb. The paper mill sludge was used for the study, and ammonium nitrate was treated to some of them to reduce the C/N ratio lower than 40. The maximum amount of applied sludge was 7ton/ha/year, and they were spread on spring and on late summer. The sludge application did not stimulate early growth of the trees during a year. Since there was no significant changes in soil chemical properties, the amount of applied sludge was thought to be too little to result in a significant role for tree growth. However, the soil water showed significant increase of Cu when the activated sludges were applied during late summer. Thus, the time of application need to be determined cautiously with considering the risk of ground water contamination. In conclusion, if we set a goal from the view point of long-term concept such as forest productivity rather than to get a short-term product, the uncomposted sludge in small amount during growing season might be considered to be applied on forest nursery.

• Journal of Sericultural and Entomological Science
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• v.55 no.2
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• pp.33-39
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• 2019

Freeze-dried silkworm powder has been approved as a functional ingredients for blood glucose control since 2009. Proximate and nutrient compositions of silkworm powder was summerized as bellow. Silkworm powder contained 4.7% moisture, 57.7% crude protein, 9.5% crude fat, 5.4% crude fiber, and 9.3% ash. The larval protein contained 18 known amino acid including glutamic acid and aspartic acid. Fat is composed of 3:7 ratio of saturated fatty acid to unsaturated fatty acid including various essential fatty acids. It contained 34.7 linolenic acid, 24.4% oleic acid, 20.2% palmitic acid, 9.2% stearic acid, and 7.7% linoleic acid. Five minerals, K, P, Ca, Mg, S were abundant in the silkworm powder with other minerals such as Cu, Mn, Fe, and Zn.