• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5357-5364
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• 2011

The objective of this study is development of carbon recycle technology which convert carbon dioxide captured from flue gas to carbon monoxide or carbon and reuse in industrial fields. Since carbon dioxide is very stable and difficult to decompose, metal oxide was used as activation agent for the decomposition of carbon dioxide at low temperature. Metal oxides which convert $CO_2$ to CO or carbon were prepared using Ba-ferrite by solid and hydrothermal synthesis. TPR/TPO and TGA were used in this study. The results of TPR by H2 and TPO by $CO_2$ showed that Ba-ferrite powders synthesized by hydrothermal method were better than those by solid method. TGA showed contrary results that reduction of Ba-ferrite powders synthesized using solid method by $H_2$ was 21.96 wt%, oxidation by $CO_2$ was 21.24 wt% and 96.72 wt% of $CO_2$ decomposition efficiency showing excellent oxidation-reduction characteristics at $500^{\circ}C$.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.5
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• pp.461-467
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• 2005

Phthalate esters is recently considered as an environmental pollutant. This study investigated removal methods of phthalate esters in water environment. On tap water treatment condition with batch test, removal efficiency of coagulation precipitation of one oxidation were $26.6{\sim}33.8%$ and $10{\sim}15%$, respectively. Phthalate esters was effectively removed by the activated carbon adsorption process on tap water treatment condition. The operation of raw water with EBCT of 10 minutes on continuous process satisfied the standard of drinking water by the WHO and US EPA when the concentration of phthalate esters was $100\;{\mu}g/L$. On pilot plant test, coagulation precipitation process got $32{\sim}44%$ of removal efficiency, sand filtration process $6{\sim}10%$ and ozone oxidation process $8{\sim}10%$, respectively. DEP, DBP, BBP and DEHP were not detected after the raw water was processed with activated carbon. The actual survey of phthalate esters removal by advanced water treatment showed that $29{\sim}76%$, $3{\sim}29%$ and $17{\sim}22%$ of phthalate esters were removed on coagulation precipitation process, sand filtration and ozone oxidation process, respectively. DEP, DBP, BBP and DEHP were not detected after the raw water was processed with activated carbon.

• Journal of Microbiology and Biotechnology
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• v.15 no.2
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• pp.234-238
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• 2005

Glucose oxidase was immobilized on the carboxylated multi-wall carbon nanotubes (MWNT-COOHs) in the presence of a coulping reagent, 1-ethy1-3-(3-dimethylaminopropy1) carbodiimide. Significant amounts of glucose oxidase were also immobilized on MWNT-COOHs without the coupling reagent. Various conditions for the immobilization of glucose oxidase were optimized. Optimal pH for the maximal activity of the immobilized glucose oxidase shifted to 7 from the optimal pH of 6 for the maximal activity of free enzyme due to the carboxy1 groups on the surface of MWNT-COOHs. An electrode of graphite rod with a diameter of 6 mm was fabricated using the immobilized glucose oxidase. The cyclic voltammetry study of the enzyme electrode revealed that the oxidation of glucose and subsequent transfer of electrons from the oxidation of glucose to the electrode were possible by the immobilized glucose oxidase without a mediator, implying that the enzyme electrode can be utilized for the development of biofuel cells.

• Journal of Electrochemical Science and Technology
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• v.9 no.2
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• pp.109-117
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• 2018

A novel carbon paste electrode modified with $Cu-TiO_2$ nanocomposite, 2-(ferrocenylethynyl)fluoren-9-one (2FF) and ionic liquid (IL) (2FF/$Cu-TiO_2$/IL/CPE) was fabricated and employed to study the electrocatalytic oxidation of droxidopa, using cyclic voltammetry (CV), chronoamperometry (CHA) and differential pulse voltammetry (DPV) as diagnostic techniques. It has been found that the oxidation of droxidopa at the surface of modified electrode occurs at a potential of about 295 mV less positive than that of an unmodified CPE. DPV exhibits a linear dynamic range from $5.0{\times}10^{-8}$ to $4.0{\times}10^{-4}M$ and a detection limit of 30.0 nM for droxidopa. Finally this modified electrode was used for simultaneous determination of droxidopa and tryptophan. Also the 2FF/$Cu-TiO_2$/IL/CPE shows excellent ability to determination of droxidopa and tryptophan in real samples.

• Carbon letters
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• v.26
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• pp.88-94
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• 2018

This manuscript explains the effective determination of urea by redox cyclic voltammetric analysis, for which a modified polypyrrole-graphene oxide (PPY-GO, GO 20% w/w of PPY) nanocomposite electrode was developed. Cyclic voltammetry measurements revealed an effective electron transfer in 0.1 M KOH electrolytic solution in the potential window range of 0 to 0.6 V. This PPY-GO modified electrode exhibited a moderate electrocatalytic effect towards urea oxidation, thereby allowing its determination in an electrolytic solution. The linear dependence of the current vs. urea concentration was reached using square-wave voltammetry in the concentration range of urea between 0.5 to $3.0{\mu}M$ with a relatively low limit of detection of $0.27{\mu}M$. The scanning electron microscopy was used to characterize the morphologies and properties of the nanocomposite layer, along with Fourier transform infrared spectroscopy. The results indicated that the nanocomposite film modified electrode exhibited a synergistic effect, including high conductivity, a fast electron-transfer rate, and an inherent catalytic ability.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.4
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• pp.30-37
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• 1997

This thesis is concerned with the study on the characteristics of the tool failure occuring at the beginning of cutting in finish machining of hardened steels such as carbon tool steel and alloy tool steel by a ceramic tool (Al$_{2}$O$_{3}$+TiC) with nose radius. In the machining of hardened carbon steel STC3, the wear mechanism on the flank face of the ceramic tool is abrasion wear. The mode of tool failure is developed into catastropic fracture with flaking. It is thought that the fracture caused by FeO and TiO$_{2}$ results from the oxidation of Fe in the workpice and TiC in the ceramic tool and the deposit of Fe formed on the surface of the ceramic tool. In the machining of hardened alloy steel STD11, the wear mechanism on the flank face of the ceramic tool is that abrasion and adhesion wear exist simultaneously. The mode of tool failure at the beginning of cutting features is DOC notch wear. It is thought that the DOC notch wear caused by FeO and TiO$_{2}$results from the oxidation of Fe and TiC in the workpiece and ceramic tool, respectively.

• Journal of Radiation Industry
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• v.3 no.1
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• pp.1-5
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• 2009

The variation of MgO surfaces, in which fluorine was contained (F-MgO), by high energy electron-beam (EB) was studied using X-ray photoelectron spectroscopy (XPS). Fluorine on the MgO surface was eliminated by EB treatment with the consequence that the electronic structures of Mg, O and C were varied. Moreover, as a result of oxidation of carbon species on the surface by high dose EB treatment (90 kGy), the concentration of carbonate and carboxyl species on the surface was increased. In this experiment, it was confirmed that the structure of oxidized metal surface can be adjusted by varying conditions of EB treatment (energy and dose). This result implies that EB can be applied for developing new catalysts.

• Korean Journal of Metals and Materials
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• v.47 no.2
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• pp.107-113
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• 2009

Molten iron with 2 mass % carbon content was decarbonized at 1823 K~1923 K by bubbling $Ar+O_2$ gas through a submerged nozzle. The reaction rate was significantly influenced by the oxygen partial pressure and the gas flow rate. Little evolution of CO gas was observed in the initial 5 seconds of the oxidation; however, this was followed by a period of high evolution rate of CO gas. The partial pressure of CO gas decreased with further progress of the decarbonization. The overall reaction is decomposed to two elementary reactions: the decarbonization and the dissolution rate of oxygen. The assumptions were made that these reactions are at equilibrium and that the reaction rates are controlled by mass transfer rates within and around the gas bubble. The time variations of carbon and oxygen contents in the melt and the CO partial pressure in the off-gas under various bubbling conditions were well explained by the mathematical model. Based on the present model, it was explained that the decarbonization rate of molten iron was controlled by gas-phase mass transfer at the first stage of reaction, but the rate controlling step was transferred to liquid-phase mass transfer from one third of reaction time.

• Journal of the Korean Solar Energy Society
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• v.30 no.5
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• pp.11-16
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• 2010

Methane hydrate is crystalline ice-like compounds which formed methane gas enters within water molecules composed cavity and each other from physically-bond at specially temperature and pressure condition. $1m^3$ of methane hydrate can be decomposed into the maximum of $216m^3$ of methane gas under standard condition. If these characteristics of hydrate are utilized in the opposite sense, natural gas can be fixed into water in the form of a hydrate solid. Therefore the use of hydrate is considered to be a great way to transport and store natural gas in large quantity. However, when methane hydrate is formed artificially, the amount of gas that is consumed is relatively low, due to the slow reaction rate between water and methane gas. Therefore for practical purposes in the application, the present investigation focuses on increasing the amount of gas consumed by adding chemically oxidized OMWCNTs to pure water. The results show that when 0.003 wt% of oxidation multi-walled carbon nanotubes was added to pure water, the amount of gas consumed was almost four times more than that of pure water indicating its effect in hydrate formation and the hydrate formation time decreased at alow subcooling temperature.

• Corrosion Science and Technology
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• v.7 no.3
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• pp.182-186
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• 2008

The microstructures of the oxide scale developed at high temperature on steels are very complex and their development depends on many factors including time, temperature, oxidation conditions and alloying elements. The classical model of an oxide scale on steel consisting of wüstite, magnetite and haematite layers, is more complicated in reality and its properties change with the factors that affect their development. An understanding of the oxide scale formation and its properties can only be achieved by careful examination of the scale microstructure. The oxide scale microstructure may be difficult to characterise by conventional techniques such as optical or standard scanning electron microscopy. An unambiguous characterisation of the scale and the correct identification of the phases within the scale are difficult unless the crystallographic structure for each phase in the scale is considered and a simultaneous microstructure-microtexture analysis is carried out. In the current study Electron Backscatter Diffraction (EBSD) has been used to investigate the microstructure of iron oxide layers grown on low carbon steels at different times and temperatures. EBSD has proved to be a powerful technique for identifying the individual phases in the oxide scale accurately. The results show that different grain shapes and sizes develop for each phase in the scale depending on time and temperature.