• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.160-163
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• 2001

본 연구에서는 Fe$^{0}$ /$H_2O$$_2$ 시스템을 이용하여 디젤 오염토양의 산화처리효율과 경제성 향상을 위한 실험을 수행하였다. 앞선 연구결과에서 최적 pH조건은 3이었으며, 과산화수소와 철 분말의 양은 비례적으로 증가할수록 처리효율이 높게 나타났다. 1) 이번 연구에서는 pH조절에 따른 처리효율의 향상효과를 알아보기 위해 pH 값을 3으로 일정하게 유지하여 반응을 수행하였으며, 일정 철 분말 농도조건에서 과산화수소의 주입방법에 따른 반응변화를 살펴보기 위해 과산화수소를 여러 비율로 분할 주입하면서 실험을 실시하였다. 본 연구결과에 따르면 pH를 3으로 일정하게 유지함으로써 초기에만 pH를 3으로 조정한 이전의 연구에서 반응이 경과함에 따라 나타나는 pH상승에 따른 처리효율의 감소 효과를 줄며 전체적인 TPH 처리효율을 10%이상 높일 수 있었으며, 같은 양의 TPH 제거에 소모되는 과산화수소의 양을 20% 정도 줄일 수 있었다. 과산화수소의 분할주입에 따른 반응향상효과 실험에서는 5회에 걸쳐 분할 주입한 경우에 3시간 이후 경미한 반응성 향상효과를 얻을 수 있었다. 이러한 결과는 과산화수소를 분할하여 주입함으로써 한번에 주입한 경우에 비하여 유기물의 산화에 직접적으로 참여하지 않는 과산화수소의 scavenging 효과를 최소화할 수 있음을 보여주는 것이다. 따라서 최적 pH의 일정 유지와 과산화수소의 분할주입으로 철 분말을 이용한 펜톤유사반응의 처리효율과 경제성 제고 모두에 있어서 효과가 있음을 알 수 있었다.

• KSBB Journal
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• v.18 no.6
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• pp.517-521
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• 2003

Superoxide dismutase which is metalloenzyme that decomposes superoxide radicals into hydrogen peroxide and molecular oxygen. Vitreoscilla has FeSOD. Expression of FeSOD to paraquat was largely constitutive. This suggests that the basal level of FeSOD is sufficient to provide protection against superoxide generated during normal aerobic metabolism. Induction of SOD by iron supports that insertion of the active site metal into the corresponding apoprotein. The effect of paraquat on induction by iron seemed that iron brought the synergism effect in SOD activity with paraquat. It suggests that the relief of growth inhibition is due to protection against the lethality of O$_2$afforded by the elevated SOD. There may be control of FeSOD activity posttranslationally. Posttranslation control of enzyme function is particularly feasible for a metalloenzyme, for which conversion of apo- to holoenzyme may be the rate-limiting or regulatory step.

• Journal of the Korean Ceramic Society
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• v.40 no.11
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• pp.1106-1112
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• 2003

For the purpose of making clear the role of oxygen in the thermoelectric properties of FeSi$_2$, thermoelectric measurements and spectroscopic characterization were conducted for the oxidized specimens fabricated from ($\alpha$+$\varepsilon$)-phases and/or $\beta$-phase. Addition of oxygen to FeSi$_2$ prevented both densification during sintering and transformation from metallic phases to semiconducting phase during annealing treatment. In an specimens, electrical conductivity and thermal conductivity decreased with oxidation time. The Seebeck coefficient was positive and small for pure FeSi$_2$. And/or the oxidized specimens fabricated from ($\alpha$+$\varepsilon$)-phases. However, it was negative and showed a maximum peak at about 500 K for the oxidized FeSi$_2$ fabricated from $\beta$-phase. The value of maximum peak increased with oxidation time.

• Journal of the Korean Magnetics Society
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• v.3 no.2
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• pp.130-134
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• 1993

The magnetic properties of the amorphous $Fe_{73.5-X}Co_{X}Cu_{1}Nb_{3}Si_{13.5}B_{9}(x=2,\;4)$ alloys, fabricated by a single roll rapid quenching technique and annealed at $400~650^{\circ}C$, have been investigated. The optimum annealing temperature is $550^{\circ}C$ for the amorphous $Fe_{71.5}Co_{2}Cu_{1}Nb_{3}Si_{13.5}B_{9}$ alloy. The properties of the nanocrystalline $Fe_{71.5}Co_{2}Cu_{1}Nb_{3}Si_{13.5}B_{9}$ alloy show the relative permeability of $1.1{\times}10^{4}$ and the coercive force of 0.22 Oe at 1 kHz. When annealed at $600^{\circ}C$, the nanocrystalline $Fe_{69.5}Co_{4}Cu_{1}Nb_{3}Si_{13.5)B_{9}$ alloy shows the relative permeability of $1.0{\times}10^{4}$ and the coercive force of 0.19 Oe at 1 kHz. From the X-ray measurement, it is found that the remarkably improved soft magnetic properties are the effect of the formation of $\alpha$-Fe(Si) grain. By the results of FMR exper-imeIlt, the optimum annealing condition is just below temperature which the peak-to-peak line width of FMR spectrum increase rapidly.

• Journal of the Korean Electrochemical Society
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• v.17 no.4
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• pp.229-236
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• 2014

In this study, the method to improve the electrochemical performance of $LiFePO_4$ by carbon coating and morphology control into porous structure was studied. The synthesis of $LiFePO_4$ was done by coprecipitation method by two step procedure. In the first step $FePO_4$ precursor was synthesized by coprecipitation method, followed by impregnation of lithium into the precursor at $750^{\circ}C$. The carbon coating was done by both physical and chemical coating processes. Using the physical coating process, the amount of coating layer was 6% and the capacity achieved was 125 mAh/g. In case of chemical coating process, the active material delivered 130~140 mAh/g, which is about 40% improvement of delivered capacity compared to uncoated $LiFePO_4$. For the morphology control into porous structure, we added nano particles of $Al_2O_3$ or $SiO_2$ into the active materials and formed the nanocomposite of ($Al_2O_3$ or $SiO_2$)/$LiFePO_4$. Between them, $SiO_2/LiFePO_4$ porous nanocomposite showed larger capacity of 132 mAh/g.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.118-123
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• 2017

To manufacture MG-Si (Metallurgical grade silicon) for use in various industries, Acid leaching experiments were performed to remove aluminum (Al) and iron (Fe), which are the most common impurities found in the silicon raw material. The silicon raw material was reacted with five types of acids (HCl, HF, H2SO4, HNO3, H3PO4) at 1, 2, 4, and 6M; 1M HF showed the highest Al and Fe removal rates, 97.9% and 95.2%, respectively. HF, however, resulted in an 18% reduced yield due to the silicon corrosion properties. To minimize the yield reduction, 2M HCl, which has a second removal ratio result, was mixed with 1M HF and applied to the silicon raw material. The experiment was conducted to select the optimal conditions for the mixed solution, which were $80^{\circ}C$ and 2hr. Under the optimal conditions, the residual Al and Fe concentrations were 141 ppmw and 93 ppmw, respectively, and it very easy to produce MG-Si with 3N grade purity.

• Journal of Korean Association for Spatial Structures
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• v.10 no.2
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• pp.77-86
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• 2010

This paper provides background theories and numerical results of automatic finite element (FE) mesh generation for freeform discrete structures. The present method adopts the computer aided geometric design (CAGD) technique to overcome the limitation of case-sensitive traditional automatic FE mesh generator. The present technique involves two steps. The first one is to represent the shape of the structure using the geometric model based on the CAGD and the second one is to generate the discrete FE mesh of spatial structures over the geometric model. From numerical results, it is found to be that the present technique is very easy to produce the FE mesh for free-form spatial structures and it can also reuse some features of traditional automatic mesh generator in the process. Furthermore, it shows the possibility to be used for the shape optimization of large spatial structures.

• Korean Journal of Environmental Agriculture
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• v.18 no.3
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• pp.209-214
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• 1999

Objective of the research is to estimate neutralization capacity and to determine practical running parameters required in packing tower design of waste oyster shells using Bohart-Adams equation. It is expected that waste oyster shells are able to be recycled for removal of heavy metals through neutralization of plating wastewater because those contain approximate 93% $CaCO_3$. By applying the results of the continuous experiment to Bohart-Adams equation, service time decreases in the order of Cr>Fe>Cu, while removal efficiencies of metals become less in the order of Fe>Cr>Cu.

• Journal of the Korean Chemical Society
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• v.33 no.3
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• pp.309-314
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• 1989

A kinetic study was carried out for the redox reaction of cis-$[Co(en)_2(N_3)_2]^+$ with Fe(II) in acidic solution by spectrophotometric methods. This redox reaction system have been found to show a third order for overall reaction as the respective first order with respect to reactant cis-$[Co(en)_2(N_3)_2]^+$, Fe(II), and $H^+$ catalyst. The activation parameters, ${\Delta}H^{\neq}$ and ${\Delta}S^{\neq}$, were obtained as 14.2Kcal/mol and -16.7 e.u., respectively. On the basis of the kinetic data, we suggest that the redox reaction system proceeds via inner sphere mechanism. The rate equation derived from the proposed mechanism is in agreement with the observed rate equation.

• Economic and Environmental Geology
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• v.57 no.3
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• pp.319-327
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• 2024

Calcite and aragonite are polymorphs with the chemical formula CaCO₃. In this study, natural limestone and aragonite, as well as scallop and clam shells composed of calcite and aragonite, were used as the pH-raising neutralizing agents for model solutions containing various heavy metals such as Cd, Cu, Fe, Mn, and Zn to simulate acidic drainage. According to the experimental results, pH-raising effect is higher in the shell materials compared to natural ores for both the calcite and aragonite types. Natural calcite and scallop shells are found to be the most suitable media for Cd removal, while over 95% efficiency for Cu and Fe removal was observed in all four media. Zn removal efficiency is higher in aragonite and clam shells, while Mn removal efficiency is relatively low, to be below 50%, for all four media. Overall, the heavy metal removal efficiency, except for Mn, was over 90%, in the order of Fe > Cu > Cd > Zn > Mn.