• Applied Microscopy
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• v.33 no.1
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• pp.49-58
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• 2003

The ${\alpha}-{\beta}$ phase transition of titanium was investigated through in-situ EF-TEM heating experiments. Three different areas of a titanium foil were observed to minimize statistical errors. Systematic recording of diffraction patterns and images was carried out from $RT{\rightarrow}600^{\circ}C{\rightarrow}900^{\circ}C{\rightarrow}RT$ on each area. The following results were obtained: (1) Transition of titanium takes place very rapidly at $900^{\circ}C$. Two phases of titanium, ${\alpha}\;and\;{\beta}$, coexist at this temperature. (2) The transited ${\beta}$-phase appears in the form of twinned plates which are arranged in rotation relationship one another. (3) Analyses of electron diffraction patterns and EDS data indicate that the thermal oxidation layer is gradually formed on the surface of titanium above $900^{\circ}C$, which hinders the reversible ${\beta}{\rightarrow}{\alpha}$ phase transition upon cooling.

• Applied Microscopy
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• v.34 no.4
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• pp.255-264
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• 2004

The three-dimensional (3D) structure of an inorganic crystal, $SmZn_{0.67}Sb_2$ (space group P4/nmm, $a=4.26{\AA}\;and\;c=10.37{\AA}$) was solved by electron crystallography. High resolution electron microscopy (HREM) images from 3 different major zone axes and selected-area electron diffraction patterns from 16 different zone axes were combined to obtain a 3D information. A crystallographic image processing (CIP) of HREM images was used for more accurate determination of the crystal structure. As a result of this electron crystallography, average phase errors (${\Phi}_{res}$) of [001], [100] and [110] HREM images are $17.0^{\circ},\;8.3^{\circ}\;and\;21.9^{\circ}$, respectively. Xray crystallography of $SmZn_{0.67}Sb_2$ has attempted to compare accuracy of the structure determination by electron crystallography, which resulted in the cell parameters of $a=4.2976(6){\AA}\;and\;c=10.287(2){\AA}$, and the R-factor ($R_{sym}$) of 4.16%.

• Journal of the Mineralogical Society of Korea
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• v.18 no.4 s.46
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• pp.289-299
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• 2005

Annealing experiments on albite powders, thin sections, and TEM specimens have been performed utilizing an optical microscope heating stage. Sample orientations were determined by optical microscope and XRD, and then confirmed by TEM diffraction patterns. Partial melting of samples occurred at $1030^{\circ}C$-l2 hr for powder, but at $1060^{\circ}C$-12 hr for TEM specimen. It is difficult to get TEM images of albite microstructures above this temperature due to thickening and the amorphous phase of the melted part. Correlative studies between optical microscopy and TEM indicated that the $1050^{\circ}C$-12 hr annealing in ambient condition was most adequate to observe tweed microstructures in albite through TEM. In situ TEM heating experiments for direct observation of tweed microstructures in albite may require annealing at slightly higher temperatures than $1050^{\circ}C$ considering the high vacuum condition inside TEM.

• Applied Microscopy
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• v.34 no.1
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• pp.23-29
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• 2004

In this study, we introduce the structural analysis of amorphous silica nanoparticles by EF-TEM electron diffraction and in-situ heating experiments. Three diffused rings were observed on the electron diffraction patterns of initial silica nanoparticles, while crystalline spot patterns were gradually appeared during the insitu heating process at $900^{\circ}C$. These patterns indicate the basic unit of $SiO_4$ tetrahedra consisting amorphous silica and gradual crystallization into the ideal layer structure of tridymite by heating. Under high vacuum condition in TEM, SiO nanoparticles were redeposited on the carbon grid after evaporation of SiO gas from $SiO_2$ above $850^{\circ}C$ and the remaining $SiO_2$ were crystallized into orthorhombic tridymite, consistent with ex-situ heating results in furnace at $900^{\circ}C$.

• Analytical Science and Technology
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• v.6 no.2
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• pp.157-165
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• 1993

The potentiostatic etching dissolution method, which had been used for the quantification of precipitates in steel, was applied to investigate the origin of cracks occurred in 304 stainless steel during processing. The morphology of crack propagation was observed by SEM. EDS and EPMA were used for the analysis of chemical composition of large precipitates on the grain boundary. The crystal structure of these large precipitates was determined by X-ray diffraction and electron diffraction. In both a stainless steel plate and a wire, the crack propagated along the grain boundary. Large precipitates on the grain boundary were identified to be $M_2C$ and $M_{23}C_6$. Potentiostatic etching dissolution method was found to be appropriate to the sample preparation for the analysis of precipitates in stainless steel.

• Food Science and Preservation
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• v.22 no.2
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• pp.174-181
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• 2015

This study investigated the physicochemical properties of three different types of rice flour prepared via dry and wet milling. The powder, soft, and hard-types of rice flour were Suwon No. 542, Suwon No. 541, and Unbong No. 30, respectively. The analysis of the proximate compositions of the different types of rice flour showed that their moisture content was 7.03~7.99%, their crude protein was 7.94~8.35%, their crude lipid was 0.71~1.49% and their crude ash was 0.25~0.82%. For the Hunter's color values, the L value was highest in the wet-milled rice flour, the a value was highest in the dry-milled rice flour, and the b value was highest in the dry-milled rice flour. All the samples showed distinctive rice starch particles in the particle analysis using scanning electron microscope. The dry-milled rice flour showed the greatest amount of irregular particles and the coarsest texture. The water absorption and water solubility indices were higher in the wet-milled soft- and hard-type rice flour. The crystallinities of the samples by X-ray diffractography were all A-type, but the crystallinity of the dry-milled hard-type rice flour was higher in diffraction degree. For the amylogram properties, the wet-milled soft-type rice flour showed the highest maximum viscosity, breakdown and setback. In the meanwhile, the dry-milled soft-type rice flour showed the highest initial pasting temperature, onset, peak, and end temperatures despite of the reverse enthalpy.