• Korean Journal of Metals and Materials
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• v.48 no.3
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• pp.262-267
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• 2010

$LiNi_{1-x}Mg_xO_2$(x=0, 0.025, 0.05, 0.075, 0.1) samples were synthesized by the solid-state reaction method. The crystal structure was analyzed by X-ray powder diffraction and Rietveld refinement. $LiNi_{1-x}Mg_xO_2$samples give single phases of hexagonal layered structures with a space group of R-3m. The calculated cation-anion distances and angles from the Rietveld refinement were changed with Mg contents in $LiNi_{1-x}Mg_xO_2$. The thicknesses of $NiO_2$ slabs were increased and the distances between the $NiO_2$ slabs were decreased with the increase in Mg contents in the samples. The electrical conductivities of sintered $LiNi_{1-x}Mg_xO_2$ samples were around $10^{-2}$ S/cm at room temperature. The electrochemical performances of $LiNi_{1-x}Mg_xO_2$were evaluated by coin cell test. Compared to $LiNiO_2$, $LiNi_{0.95}Mg_{0.05}O_2$ exhibited improved high-rate capability and cyclability due to the well-ordered layered structure by doping of Mg ion.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.112-112
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• 2015

The purposed of this work was to determine nanotube shape variation on the Ti-xNb alloys with alloying elements and applied potentials. Samples were prepared by arc melting, followed by followed by homogenization for 12 hr at $1000^{\circ}C$ in argon atmosphere. This study was evaluated the phase and microstructure of Ti-xNb alloys using an X-ray diffraction (XRD) and optical microscopy (OM). The morphology of the samples was investigated with a field-emission scanning electron microscope (FE-SEM) and energy dispersive X-ray spectroscopy (EDS). The nanotube on the alloy surface was formed in 1 M $H_3PO_4$ with small additions of NaF 0.8 wt.%. All anodization treatments were carried out using a scanning potentiostat (Model 362, EG&G, USA) at constant voltage 30 V for 120 min, respectively. The morphology of the samples was investigated with a field-emission scanning electron microscope (FE-SEM) and energy dispersive X-ray spectroscopy (EDS). Surface characteristics of nanotbue formed on Ti-xNb alloys was investigated by potentiodynamic test and potentiostatic in 0.9% NaCl solution at $36.5{\pm}1^{\circ}C$. It was observed that the changed ${\alpha}$ phase to ${\beta}$ phase with Nb content.

• Journal of the Korean GEO-environmental Society
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• v.14 no.5
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• pp.49-56
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• 2013

The necessity of exploration in deep sea increases to develop the natural resources. The deep marine sediments, which were recovered from the hydrate occurrence regions during the Ulleung Basin Gas Hydrate Expedition 2 (UBGH2), East Sea, Korea in 2010, are explored to obtain the geotechnical characteristics and strength parameters. The index properties of the specimens including the atterberg limits, specific surface, and particle size distribution are measured and compared with the previous studies. X-ray diffraction, scanning electron microscope, and X-ray energy dispersive spectroscopy are conducted to analyze the clay mineralogy, chemical composition, and microstructure of the sediments. Strength parameters and shear wave velocities are measured with the axial strain by using an instrumented triaxial device. The strength parameters estimated by empirical equations are compared with the experimental results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.107-110
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• 1997

LiMn$_2$O$_4$ is prepared by reacting stoichiometric mixture of LiOH . $H_2O$ and MnO$_2$ (mole ratio 1 ; 1) and heating at 80$0^{\circ}C$, $700^{\circ}C$ for 24h, 36h, 48h, 60h and 72h. We obtained through X-ray diffraction that lattice parameter varied as function of calcined temperature and time. Cathode active materials calcined at 80$0^{\circ}C$ for 36h, (111)/(311) peak ratio was 0.37. It showed good charge/discharge characteristics. When (111)/(311) peak ratio was 0.37, it was that crystal structure is formed very well. In the result of charge/discharge test, when heated at 80$0^{\circ}C$ for 36h, charge/discharge characteristics of LiMn$_2$O$_4$ is the best.

• Nuclear Engineering and Technology
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• v.55 no.9
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• pp.3121-3125
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• 2023

Neutron conversion detectors that use ¹⁰B-enriched boron carbide are feasible alternatives to ³He-based detectors. We prepared boron carbide films at micron-scale thickness using direct-current magnetron sputtering. The structural characteristics of natural B₄C films, including density, roughness, crystallization, and purity, were analyzed using grazing incidence X-ray reflectivity, X-ray diffraction, X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and scanning electron microscopy. A beam profile test was conducted to verify the practicality of the ¹⁰B-enriched B₄C neutron conversion layer. A clear profile indicated the high quality of the neutron conversion of the boron carbide layer.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.303-303
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• 2015

In order to investigate ion release and biocompatibility of Ti-6Al-4V dental alloy by electrochemical corrosion test and MTT assay, commercial Ti-6Al-4V alloy rod (99.99% Ti, USA, Co) were used in the study. The microstructure of the alloys was examined by optical microscopy (OM), Field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), MTT assay, and corrosion test. From the polarization curves, very low current densities were obtained for Ti-6Al-4V alloys, indicating a formation of stable passive layer.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3145-3150
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• 2010

Ruthenium catalysts modified by selenium have been introduced as alternative materials to Pt in Direct methanol fuel cells (DMFCs). RuSe nano-particles were synthesized on the Vulcan XC72R carbon supports via polyol method. The prepared catalysts were electrochemically and physically characterized by cyclic voltammetry (CV,) linear sweep voltammetry, methanol tolerance test, X-ray diffraction (XRD), Transmission electron microscopy (TEM), Energydispersive Spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). Increasing the Se concentration up to 20 at % increased the electro-catalytic activity for the oxygen reduction. By increasing Se amount, Ru metallic form on the surface was increased. The $Ru_{80}Se_{20}$/C catalysts showed the highest oxygen reduction reaction (ORR) activity and outstanding methanol tolerant property in half cell tests as well as single cell test.

• Journal of Pharmaceutical Investigation
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• v.35 no.4
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• pp.279-285
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• 2005

Ground CS-891 (N-[1-(4-methoxyphenyl)-1-methylethyl]-3-oxo-4-aza-5a-androst-1-ene-$17{\beta}$-carboxamide) of poorly water soluble drug was obtained using a Heiko Seisakusho model TI-100 vibration mill, and samples with different crystallinity were prepared at mixture ratios of 10:0, 7:3, 5:5, 3:7 and 0:10 (intact;ground CS-891). Physicochemical characterizations were obtained using qualitative and quantitative X-ray diffractometry, different scanning calorimetry (DSC), scanning electron microscopy (SEM), Quantasorb surface area analyzer, and controlled atmosphere microbalance. With increase of amorphous CS-891 in mixture ratios, the intensities of X-ray diffraction peaks of crystalline CS-891 were decreased, whereas surface area, water absorption, and exothermic peaks in DSC were increased. The apparent solubility of ground CS-891 was $4.4\;{\mu}g/ml$ and the solubility of intact CS-891 was $3.1\;{\mu}g/ml$ at $37{\pm}1^{\circ}C$. The apparent precipitation rates of CS-891 in a supersaturated solution during the solubility test were increased with an increase of amorphous CS-891, and a crystalline form of CS-891 transformed from amorphous CS-891 after the solubility test was found by X-ray diffraction analysis, DSC and SEM. The dissolution profiles of CS-891 with different crystallinity at $37{\pm}1^{\circ}C$ by the USP paddle method were investigated, and the apparent dissolution rate constant of ground CS-891 was about 5.9-fold higher than that of intact CS-891. A linear relationships between the crystallinity of CS-891 and the apparent dissolution rate constant (r>0.96) were obtained.

• Journal of Environmental Science International
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• v.5 no.2
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• pp.203-210
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• 1996

To improve coagulation characteristics and to reduce dossage of chemicals in watertreatment, polyaluminium sulfate was manufactured by reaction of polymerization between aluminium sulfate and sodium aluminate. As the results of affirmation and performance test, the yield of product was about 24% from molecular cut on levels by ultrafilteration method. The type of molecular is nearly affirmated as a kind of complex like AIm(OH)n(3m-n)+ from Scanning Electron Microscopy (S.E.M.) and X-ray diffraction test. Since the synthesized polymer was supposed to be quasi, further study for stabilization was required.

• Journal of Powder Materials
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• v.2 no.3
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• pp.201-207
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• 1995

In general, the characteristics of plasma spray coating are strongly dependent on process conditions. In this paper, Mo and Co alloy coating layers were made by plasma spraying with different spray parameters and characterized using X-ray diffraction, scanning electron microscopy(SEM), hardnass test, and wear test. It was found that the coating characteristics were mainly affected by phase composition of the powder, spray distance, arc current, and gas flow rate.