• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.2
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• pp.115-120
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• 2013

This study examined the removal rate of mixed heavy metals from aqueous solution using recycled aggregate. The recycled aggregate is favorable for the absorbent because it contains about 95% (CaO, $SiO_2$, $Al_2O_3$ and $Fe_2O_3$), which are major ingredient of adsorbent for heavy metal. The kinetic data presented that the slow course of adsorption follows the Pseudo first and second order models. The equilibrium data were well fitted by the Langmuir model and showed the affinity order: $Cu^{2+}$ > $Pb^{2+}$ > $$Zn^{2+}{\simeq_-}Ni^{2+}$$ > $Cd^{2+}$. The results also showed that adsorption rate slightly increased with increasing pH from 6 to 10. Moreover, this trend is similar to results obtained as function of loading amount of recycled aggregate. Meanwhile, an unit adsorption rate was slightly decreased. From these results, it was concluded that the absorbents can be successfully used the removal of the heavy metals from the aqueous solutions.

• The Magazine of the IEIE
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• v.34 no.12
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• pp.38-48
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• 2007

• Corrosion Science and Technology
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• v.14 no.3
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• pp.127-131
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• 2015

Model alloys Fe-9Cr, Fe-20Cr and Fe-20Cr-20Ni (wt. %) with 0.1 and 0.2 % Si were exposed to $Ar-20CO_2-20H_2O$ gas at $818^{\circ}C$. The undoped alloys formed a thick iron-rich oxide scale. The additions of Si reduced scaling rates of Fe-9Cr to some extent but significantly suppressed the formation of iron oxide scales on Fe-20Cr and Fe-20Cr-20Ni. Carburisation also occurred in all undoped alloys, but not in Si-containing Fe-20Cr and Fe-20Cr-20Ni. Protection against carburisation was a result of the formation of an inner scale layer of silica.

• Economic and Environmental Geology
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• v.46 no.2
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• pp.199-206
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• 2013

The Daehyun gold-silver deposit consists of two hydrothermal quartz veins that fill NE-trending fractures in the Cambro-Ordovician calcitic marble. I have sampled wallrock, hydrothermaly-altered rock and gold-silver ore vein to study the element dispersion and element gain/loss during wallrock alteration. The hydrothermal alteration doesn't remarkably recognized at this deposit and consists of mainly calcite, dolomite, quartz and minor epidote. The ore minerals composed of arsenopyrite, pyrrhotite, pyrite, sphalerite, stannite, chalcopyrite, galena, electrum, native bismuth and silver-bearing mineral. Based on analyzed data, the chemical composition of wallrock consists of mainly $SiO_2$, CaO, $CO_2$ with amounts of $Al_2O_3$, $Fe_2O_3(T)$ and MgO. The contents of $SiO_2$, $Fe_2O_3(T)$, MgO, CaO and $CO_2$ vary significantly with distance from ore vein. The element dispersion doesn't remarkably recognized during wallrock alteration and only occurs near the ore vein margin because of physical and chemical properties of wallrock. Remarkable gain elements during wallrock alteration are $Fe_2O_3(T)$, total S, Ag, As, Bi, Cd, Cu, Ni, Pb, Sb, Sn, W and Zn. Remarkable loss elements are $SiO_2$, MnO, MgO, CaO. $CO_2$ and Sr. Therefore, Our result may be used when geochemical exploration carry out at deposits hosted calcitic marble in the Hwanggangri metallogenic district.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1998.04b
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• pp.28-28
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• 1998

• The Journal of the Petrological Society of Korea
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• v.16 no.4
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• pp.217-232
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• 2007

The Puu Oo eruption in Hawaii since 1983 is one of the largest eruptions on Hawaii's volcanic history with prominent compositional variation ($5.6{\sim}10.1wt.%$ in MgO content). Although intense researches of Hawaiian eruption have been conducted for recent years, there is no up-to-date study on Puu Oo lavas that is erupting hot lavas today. in oder to obtain basic information on the geological characteristics of the eruption including any noticeable change in its petrological trend and magma dynamics, we applied several geological approaches such as field survey, systematic sampling, petrography, mineralogy, and geochemistry. Clinopyroxene and Plagioclase phenocrysts are rarely observed on the thin section, however Olivine crysts are much more obvious in the study area. It indicates that Puu Oo is early stage of magma differentiation. Variation diagram of whole rock composition shows that the elements such as $TiO_2,\;Al_2O_3,\;SiO_2$ and $Na_2O$ decrease with increasing MgO. In the trace element Sr, Y Zr and V versus $K_2O$, P18, P19 samples are plotted in primitive area. Variations of the Ni contents during $2003{\sim}2006$ may suggest a sudden change in magma composition probably caused by new magma injection.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1331-1332
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• 2006

The present investigation has attemped to optimize hydrogen reduction process for the mass production of Fe-8wt%Ni nanoalloy powder from ball milled $Fe_2O_3-NiO$ powder. In-situ hygrometry study was performed to monitor the reduction behavior in real time through measurement of water vapor outflowing rate. It was found that the reduction process can be optimized by taking into account the apparent influence of water vapor trap in the reactor on reduction kinetics which strongly depends on gas flow rate, reactor volume and reduction.

• Bulletin of the Korean Chemical Society
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• v.19 no.1
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• pp.5-21
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• 1998

The purpose of this paper is to show that X-ray absorption spectroscopy (XANES and EXAFS) is a powerful technique for characterizing both crystalline and amorphous solids from structural (local order) and electronic point of view. The principle of this technique is briefly described by showing the main factors which must be considered for recording and fitting the experimental results. Some non-trivial examples have been selected for demonstrating that XAS spectroscopy is the only technique for bringing a definitive answer as for example: the determination of the local distortion of the $NiO_6$ octahedra in the $Li_{1-z}Ni_{1+z}O_2$ layered oxides and the evidence of the presence of copper pairs in the NASICON-type phosphate $CuZr_2 (PO_4)_3$. Are also reported some significant examples for which XAS spectroscopy is decisive with other characterization methods as (i) Raman spectroscopy for glasses (ii) Mossbauer spectroscopy for $LiNi_{1+z-t}Fe_To_2$ oxides (iii) magnetic measurements for Ce-based intermetallic compounds.

• Journal of the Korean Electrochemical Society
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• v.7 no.2
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• pp.94-99
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• 2004

Anode-supported flat tubular solid oxide fuel cell (SOFC) was investigated to increase the cell power density. The anode-supported flat tube was fabricated by extrusion process. The porosity and pore size of Ni/YSZ ($8mol\%$ yttria-stabilized zirconia) cermet anode were $50.6\%\;and\;0.23{\mu}m$, respectively. The Ni particles in the anode were distributed uniformly and connected well to each other particles in the cermet anode. YSZ electrolyte layer and multilayered cathode composed of $LSM(La_{0.85}Sr_{0.15})_{0.9}MnO_3)/YSZ$ composite, LSM, and $LSCF(La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.7}O_3)$ were coated onto the anode substrate by slurry dip coating, subsequently. The anode-supported flat tubular cell showed a performance of $300mW/cm^2 (0.6V,\; 500 mA/cm^2)\;at\;500^{\circ}C$. The electrochemical characteristics of the flat tubular cell were examined by ac impedance method and the humidified fuel enhanced the cell performance. Areal specific resistance of the LSM-coated SUS430 by slurry dipping process as metallic interconnect was $148m{\Omega}cm^2\;at\;750^{\circ}C$ and then decreased to $148m{\Omega}cm^2$ after 450hr. On the other hand, the LSM-coated Fecralloy by slurry dipping process showed a high area specific resistance.

• Journal of Sensor Science and Technology
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• v.28 no.1
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• pp.41-46
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• 2019

In order to develop novel thermal imaging materials for microbolometer applications, $[(Ni_{0.3}Mn_{0.7})_{1-x}Cu_x]_3O_4$ ($0.18{\leq}x{\leq}0.26$) thin films were fabricated using metal-organic decomposition. Effects of Cu content on the electrical properties of the annealed films were investigated. Spinel thin films with a thickness of approximately 100 nm were obtained from the $[(Ni_{0.3}Mn_{0.7})_{1-x}Cu_x]_3O_4$ films annealed at $380^{\circ}C$ for five hours. The resistivity (${\rho}$) of the annealed films was analyzed with respect to the small polaron hopping model. Based on the $Mn^{3+}/Mn^{4+}$ ratio values obtained through x-ray photoelectron spectroscopy analysis, the hopping mechanism between $Mn^{3+}$ and $Mn^{4+}$ cations discussed in the proposed study. The effects of $Cu^+$ and $Cu^{2+}$ cations on the hopping mechanism is also discussed. Obtained results indicate that $[(Ni_{0.3}Mn_{0.7})_{1-x}Cu_x]_3O_4$ thin films with low temperature annealing and superior electrical properties (${\rho}{\leq}54.83{\Omega}{\cdot}cm$, temperature coefficient of resistance > -2.62%/K) can be effectively employed in applications involving complementary metal-oxide semiconductor (CMOS) integrated microbolometer devices.