• Journal of the Korean Ceramic Society
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• v.33 no.7
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• pp.785-792
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• 1996

Formation of Solid Solution and Microstructure in Processureless sintered SiC-AlN compo-site using oxides as a sintering aid at 185$0^{\circ}C$ and 195$0^{\circ}C$ Regardless of SiC/AlN ratio in composition most of sintered specimens showed he complex structure mixed with 2H solid solution and SiC particles. High sintering temperature and large AlN content in starting composition enhanced the formation of 2H solid solution in sintered specimen 2H solid solution showed the spherical shape and core-rim structure. AlN content in the core is higher than that in the rim but SiC content . The size of 2H solid solution on fracture showed the transgranular fracture mode compared with the dispersed SiC particles which showed the intergranular fracture mode.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.6
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• pp.389-395
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• 2023

Damping capacities of Mg-2.5%Al and Mg-2.5%Zn (in atomic) solid solutions were comparatively investigated in order to clarify the influence of solutionized Al and Zn elements on the damping characteristics of Mg. In this study, solid solutions with similar grain size were obtained by solution treatment at 678 K for different times (24 h for Mg-2.5%Al and 36 h for Mg-2.5%Zn), followed by water quenching at RT. The Mg-2.5%Al and Mg-2.5%Zn solid solutions showed similar damping capacities in the strain-amplitude independent region of 1 × 10^-6 ~ 1 × 10^-5 and in the strain-amplitude dependent region below 6 × 10^-4, over which the Mg-2.5%Zn solid solution possessed better damping capacity than the Mg-2.5%Al solid solution. The damping tendencies depending on strain-amplitude for the two solid solutions were analyzed and discussed in terms of similar length between weak pinning points (solutes) and different solute/dislocation interaction forces in Granato-Lücke model.

• Journal of Environmental Science International
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• v.24 no.1
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• pp.47-53
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• 2015

Removal characteristics of Cu(II) ions by solid-phase extractant immobilized D2EHPA and TBP in PVC were investigated. Cu(II) ion concentrations in the solution and removal capacity of Cu(II) ion according to operation time were compared. The lower the initial concentration of Cu(II) ion in aqueous solution was, the removal capacity of Cu(II) ion by solid-phase extractant was increased relatively. The bigger the initial concentration of Cu(II) ion was, the removal capacity of Cu(II) ion was increased relatively. The pseudo-second-order kinetics according to operation time was showed more satisfying results than the pseudo-first-order kinetics for the removal velocity of Cu(II) ion. The removal capacity of Cu(II) ion was 0.025 mg/g in aqueous solution of pH 2, but the removal capacity of Cu(II) ion was increased to 0.33 mg/g mg/g in aqueous solution of pH 4 according to increasing pH.

• Korean Journal of Environmental Biology
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• v.17 no.2
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• pp.183-190
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• 1999

The bioleaching of heavy metals from fly ash was performed by Thiobacillus thiooxidans MET isolated from the enrichment culture of an anaerobically digested sludge. The effect of solid concentrations on the efficiency of metal leaching was studied in shaken flasks. In the range of solid concentrations 20 g.L­$^1$to 100 g.L­$^1$T. thiooxidans MET oxidized S$^{0}$ to sulfate without any lag period. The final pH of slurry solution was decreased to below pH 1, and the final oxide-redox potential (ORP) was increased to over 420 mV in the solid concentrations below 100 g.L­$^1$. However, the initial lag period of 4 to 8 days was required to obtain the pH reduction and ORP increase of the slurry solutions in the range of solid concentrations 150 g.L­$^1$to 300 g.L­$^1$. The sulfur oxidation rate of T. thiooxidans MET in 20~100 g.L­$^1$solid concentrations was 0.70~0.75 g-S.L­$^1$ㆍ d­$^1$, but its sulfur oxidation activity was remarkably inhibited with increasing solid concentration over 150 g.L­$^1$. Increasing fly ash solids concentration in the range of solids concentration 20 g.L­$^1$ to 200 g.L­$^1$decreased the removal efficiency of Zn, Cu, Mn, Cr and Pb. The solubilization of heavy metals from fly ash was strongly correlated with the pH value of slurry solution. When the pH of slurry solution was reduced to 3, the solubilization process of Zn, Cu and Mn started, and their solubilization efficiency of Zn, Cu and Mn was progressively increased below pH 2. However, the solubilization process of Cr and Pb started at pH 2.5 and 2.0, respectively.

• Journal of the Korean Magnetic Resonance Society
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• v.1 no.1
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• pp.1-6
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• 1997

Several dioxovanadate (V) complexes are synthesized and studied by solution and solid-state 51V NMR spectroscopy. In the results, large 51V chemical shift anisotropy ({{{{ DELTA delta }}a = -800 ∼720 ppm) and quadrupole coupling (e2q /h = 7.50 ∼ 9.16 MHz) were observed in the solid-state complexes. The isotropic chemical shifts of the solid samples are very close to the values obtained from solution measurements.

• The Korean Journal of Ceramics
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• v.5 no.3
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• pp.224-229
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• 1999

The preparation and toughening of SiC-AIN solid solution from powder mixtures of $\beta$-SiC, AIN and $\alpha$-SiC by hot-pressing were studied in the 1870 to $2030^{\circ}C$ temperature range. The reaction of AIN and $\beta$-SiC(3C) powders causing transformation to the 2H(wurtzite) structure appeared to depend on hot-pressing temperatures and an additive of $\alpha$-SiC. For the composition of 49wt% SiC with 2 wt% $\alpha$-SiC and 47.5 wt% AIN47.5wt% SiC with 5 wt % $\alpha$-SiC at 203$0^{\circ}C$ for 1 h, th complete solid solutions with a single phase of 2H could be obtained. The appreciable amount of $\alpha$-SiC could develop the columnar inter-grains of 4H phase and the stable 2H phase with the relatively uniform composition and grain size distributions. The effect of $\alpha$-SiC on the phases present and compositional microstructures with columnar inter-grains was invetigated using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The fracture toughness and Vickers hardness of the hot-pressed solid solutions wre examined by the indentation-fracture-test method.

• The Korean Journal of Ceramics
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• v.6 no.2
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• pp.172-176
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• 2000

Solid solutions of Ti$_{0.5}$Zr$_{0.5}$B$_2$were successfully synthesized and densified simultaneously from elemental reactants by the use of a field-activated, pressure-assisted synthesis method. The method involves the application of an electric current and mechanical pressure across reactant compacts to achieve combustion synthesis. Dense solid solutions with relative densities of up to 99% were produced and characterized by XRD, SEM, and EPMA methods. With a maximum measured temperature of 145$0^{\circ}C$ under a load of 86 MPa for 30 min, the desired dense solid solution wad synthesized.

• Bulletin of the Korean Chemical Society
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• v.26 no.10
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• pp.1512-1514
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• 2005

Catalytic properties of Ni-Zr$O_2$ catalysts prepared by coprecipitation have been studied for the gas-phase hydrogenation of 1,3-butadiene to butenes. The coprecipitation method led to the solid solution of Ni-Zr$O_2$, which contains highly resistant Ni species to thermal reduction with H2. Nickel species of the solid solution were highly dispersed in the ZrO2 lattice, so that the reduced catalysts were selective for hydrogenation of 1,3-butadiene to butenes (99.9%) even in the presence of 1-butene.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.2
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• pp.85-93
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• 2013

This study has been carried out to elucidate the characteristics of the dissolution for Thermal Decomposed Solid Waste of uranium-bearing sludge (TDSW), the removal of impurities by an alkalization in a nitric acid dissolving solution of TDSW, and the selective removal (/recovery) of uranium by an acidification in an carbonate alkali solution, respectively. TDSW generated by thermal decomposition of U-bearing sludge which was produced in the uranium conversion plant operation, was stored in KAERI as a solid-powder type. It is found that the dissolution of TDSW is more effective in nitric acid dissolution than oxidative-dissolution with carbonate. At 1 M nitric acid solution, TDSW was undissolved about 30wt% as a solid residue, and uranium contained in TDSW was dissolved more than 99%. In order to the alkalization for the nitric acid dissolving solution of TDSW, carbonate alkalization is more effective with respect to remove the impurities. At the carbonate alkali solution controlled to about 9 of pH, Al, Ca, Fe and Zn co-dissolved with U in dissolution step was removed about $98{\pm}1%$. On the other hand, U could be recovered more than 99% by an acidification at pH about 3 in a carbonate alkali solution, which was nearly removed the impurities, adding 0.5M $H_2O_2$. It was found that uranium could be selectively recovered (/removed) from TDSW.

• Journal of the Korean Chemical Society
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• v.15 no.4
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• pp.177-181
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• 1971

Free radicals of lysozyme produced by $Ti-H_2O_2$ system were studied in aqueous solution at room temperature using ESR with a continuous flow-mixing. The spectra, each consisting of a doublet with 5.5 G splitting and a broad resonance covering 80 G splitting are closely similar in shape to that for solid irradiated in vacuum at $77^{\circ}K$ and observed at room temperature immediately on warming. The result is assumed to indicate that the secondary protein radical components formed within 0.01 second, dead time of the mixing chamber, and initiated by hydrogen atom abstraction at ${\alpha}$-carbon atom of peptide chain in liquid solution at room temperature are identical to those resulting from the initial formation of a mixture of positive holes and negative ions by ionization processes as well as radical fragments by the rupture of chemical bonds in the solid during similar time at the same temperature. A broad resonance is observed with considerable amplitude on the high field side of the doublet, which is quite dissimilar to the spectra of irradiated solid lysozyme. This resonance was tentatively attributed to the polypeptide free radical in which unpaired electrons are localized on side chain.