• Resources Recycling
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• v.15 no.4 s.72
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• pp.44-51
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• 2006

Most electric arc furnace dust (EAFD) treatment processes to recover zinc from EAFD employ carbon as a reducing agent for the zinc oxide in the EAFD. In the present work, the reduction reaction of zinc oxide with carbon in the present of iron oxide was kinetically studied. The experiments were carried out at temperatures between 1173 K and 1373 K under nitrogen atmosphere using a weight-loss technique. From the experimental results, it was concluded that adding the proper amount of iron oxide to the reactant accelerates the reaction rate of zinc oxide with carbon. This is because iron oxide in the reduction reaction of zinc oxide with carbon promotes the carbon gasification reaction. The spherical shrinking core model for a surface chemical reaction control was found to be useful in describing kinetics of the reaction over the entire temperature range. The reaction has an activation energy of 53 kcal/mol (224 kJ/mol) for ZnO-C reaction system, an activation energy of 42 kcal/mol (175 kJ/mol) for $ZnO-Fe_{2}O_{3}-C$ reaction system, and an activation energy of 44 kcal/mol (184 kJ/mol) for ZnO-mill scale-C reaction system.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.1992-1996
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• 2007

This study focuses on the hydrogen embrittlement of iron tube for fuel line of PEMFC (Proton Exchange Membrane Fuel Cell). PEMFC is operated by feed of hydrogen as a reactant and steam for proton conductivity of membrane. However, the environment with hydrogen and steam occur the hydrogen-induced degradation in BOP system. When iron tube was exposed to hydrogen and steam condition for 24 hours, the oxide layer on the surface was decreased by reduction. When the ambient temperature was 90$^{\circ}C$ micro cracks were found on the surface than any other temperature. The mechanical strength of iron tube was 3% lower than that of non-experiment tube. Maximum tensile stress was decreased 8%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.74-79
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• 2019

The military vehicle produces electric power through an engine-integrated serial hybrid generator that is connected to the engine and does not have a separate generator installation space. However, depending on the mechanical characteristics of the connection between the generator and the engine, iron oxide for internal rusting and lubrication grew scattered. The iron oxide is adhered to the starter to deteriorate the starting performance, and there is a problem that the noise of the leg due to wear of the gear is increased. To solve this problem, the connection spline material and the surface treatment of the engine were improved and the shape was changed to a grease sealing type to prevent the generation of iron oxide inside. As the shape of the generator connector composing the shafting system was changed, the integrity of the structure was confirmed through the torsional endurance test. In addition, through the actual vehicle load test, it was verified that no corrosion occurred during the target life span without internal corrosion. It was confirmed that the anti-scattering structure of the grease effectively suppresses the generation of iron oxide, thereby reducing the noise generated from the generator. In this paper, we propose a fundamental solution to the degradation of the starter and the noise generation by preventing the back corrosion caused by the serial hybrid generator installed between the engine and the transmission.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.3
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• pp.379-387
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• 2008

The pH & alkalinity adjustment method by lime and carbon dioxide($CO_2$) for corrosion control in water distribution system was investigated to evaluate the corrosion characteristics of metal pipes, such as galvanized iron, copper, stainless steel, and carbon steel. When the pH in sand filtered and ozone+GAC treated water was increased with lime and $CO_2$ from 7.5 to 8.0, the concentration of residual chlorine decreased at higher pH and longer reaction time; the concentration of trihalomethane increased. The corrosion rate of coupons with corrosion control using lime and carbon dioxide was showed much smaller than those without corrosion control using pilot-scale simulated distribution system. The galvanized iron was corroded much faster than carbon steel, copper, and stainless steel. Especially, copper and stainless steel coupons were hardly corroded. The galvanized iron and carbon steel coupons with corrosion control were produced the corrosion products less than those without corrosion control by the results of environmental scanning electron microscope(ESEM) and energy dispersive x-ray spectroscopy(EDS) analyses. The galvanized iron coupon with pH and alkalinity adjustment by lime and carbon dioxide was detected about 30 percent of zinc, when the carbon steel was detected about 30 percent of calcium by calcium carbonate products formation. For the results of X-ray diffraction(XRD) analyses, the goethite(${\alpha}$-FeOOH) was identified as primary corrosion product of galvanized iron without corrosion control, while the Zinc oxide(ZnO) was found on corrosion products of galvanized iron coupon with corrosion control as the results of EDS analyses. However, the carbon steel corrosion products regardless of corrosion control were composed predominantly of maghemite(${\gamma}-Fe_2O_3$) and hematite(${\alpha}-Fe_2O_3$).

• Progress in Superconductivity and Cryogenics
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• v.23 no.3
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• pp.14-19
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• 2021

The reduction of carbon dioxide emissions becomes a global issue, the main source of carbon dioxide emissions in the Asian region is the energy conversion sector, especially coal-fired power plants. We are working to develop technologies that will at least limit the increase in carbon dioxide emissions from the thermal power plants as one way to reduce carbon dioxide emissions. Our research aims to reduce carbon dioxide emissions by removing iron oxide scale from the feedwater system of thermal power plants using a superconducting high-gradient magnetic separation (HGMS) system, thereby reducing the loss of power generation efficiency. In this paper, the background of thermal power plants in Asia is outlined, followed by a case study of the introduction of a chemical cleaning line at an actual thermal power plant in Japan, and the possibility of introducing it into the thermal power plants in China based on the results.

• Natural Product Sciences
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• v.13 no.1
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• pp.40-45
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• 2007

The methanol extract of Coscinium fenestratum, commonly own as tree turmeric, which is widely used in the indigenous system of medicine was studied for its in vitro scavenging activity in different methods viz DPPH scavenging, nitric oxide scavenging, iron chelation activity, superoxide scavenging, ABTS radical scavenging and lipid peroxidation. The results were analyzed statistically by regression method. Its antioxidant activity was estimated by $IC_{50}$ value and the values are $57.1\;{\mu}g/ml$ for DPPH radical scavenging, $36.5\;{\mu}g/ml$ for iron chelating activity, $51.7\;{\mu}g/ml$ for nitric oxide scavenging, $53.63\;{\mu}g/ml$ for ABTS scavenging, $44.2\;{\mu}g/ml$ for superoxide scavenging, and $40\;{\mu}g/ml$ for lipid peroxidation. In all the methods, the extract showed its ability to scavenge free radicals in a concentration dependent manner. The results indicate that C. fenestratum has potent antiofidant activity.

• Korean Journal of Materials Research
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• v.34 no.6
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• pp.309-314
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• 2024

The structure and magnetic properties of composite powders prepared by ball milling a mixture of Fe₂O₃·(0.4-1.0)Fe were investigated. Hysteresis loops and differential scanning calorimetry (DSC) curves are used to characterize the materials and to examine the effect of the solid state reaction induced by ball milling. The results showed that a solid state reaction in Fe₂O₃·(0.4-1.0)Fe clearly proceeds after only 1 h of ball milling. The system is characterized by a positive reaction heat of +2.23 kcal/mole. The diffraction lines related to Fe₂O₃ and Fe disappeared after 1 h of ball milling and, instead, diffraction lines of the intermediate phase of Fe₃O₄ plus FeO formed. The magnetization and coercivity of the Fe₂O₃·0.8Fe powders were changed by the solid state reaction process of Fe₂O₃ by Fe during ball milling. The coercivity of the Fe₂O₃·0.8Fe powders increased with increasing milling time and reached a maximum value of 340 Oe after 5 h of ball milling. This indicates the grain size of Fe₃O₄ was clearly reduced during ball milling. The magnetic properties of the annealed powders depend on the amount of magnetic Fe and Fe₃O₄ phases.

• Resources Recycling
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• v.7 no.4
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• pp.76-80
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• 1998

In order to establish the ICP composition analysis system of the compotes which have been producing and using the domestic iron oxides, the Sectional Committee of Iron Oxides had organized an analysis working team. which carried out the component analysis of several samples and den discussed about thou analysis results through 1 year. At the 1st meeting, the component deviation was reduced. At the 3rd meeting, the deviation range if each company was reduced below ${\pm}$20% and it means to be improved on an analysis level with Japaness steel companies.

• Textile Coloration and Finishing
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• v.15 no.5
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• pp.327-332
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• 2003

In this study, the polyurethane microcapsules for non-aqueous dyeing containing iron oxide and disperse dyes were prepared by in-situ polymerization method using hexamethylene diisocyanate(HDI) with ethylene glycol(EG). And the size, shape, and particle size distribution of microcapsules prepared were investigated. The size and shape of microcapsule were observed by optical microscope and scanning elecron microscope. The particle size distribution was analyzed by particle size analyzer. The microcapsule size and its distribution were largely effected by the existance of surface active agent in the system. When a surfactant did not exist in the system, the size distribution of microcapsules prepared was much uneven. By adding a surfactant, this phenomenon was disappeared. And the size of microcapsule was also effeced by the hydrophobicity of core material(disperse dye). It was considered due to the difference of dispersity of core materials. And the size of microcapsule prepared was inversely proportional to the stirring speed.

• Journal of the Korean Society of Combustion
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• v.16 no.2
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• pp.33-39
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• 2011

We demonstrated heat generation efficiency of the magnetic hyperthermia system to find optimal condition using gelatin tissue phantom. Magnetic hyperthermia induction can be used to make heat generation with different concentration of $Fe_3O_4$ iron oxide inside tissue phantom and magnetically labeled cells by applying AC magntic field at a frequency of 145 kHz. It was observed that the maximum temperature achieved in the magnetic gelatin tissue phantom increased with the concentration of $Fe_3O_4$ iron oxide and alternating magnetic field intensity. Results were discussed with respect to further optimization of therapeutic technique for biomedical application with modified functional nanoparticles.