• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1995.10a
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• pp.167-171
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• 1995

The formation of preferred orientations in cold rolled and recrystallized Inconel 690 sheets was studied by the x-ray texture measurements and TEM observations. The increasing{220} pole intensity in the plane normal at the higher reductions was related to the{110}<112> texture component. The rolling texture of the Inconel 690 was the pure metal type. THe dislocation cells were found in the near{110}<112> oriented grains. The onset of deformation twins in the {112}<111>oriented grains. The onset of deformation twins in the {112}<111> oriented grains. The onset of deformation twins in the {112}<111> oriented grains caused the weakening of {112}<111> and the development of {552}<115> in the rolling texture. The annealing texture of the Inconel 690 sheets was dependent on the annealing temperature. The annealing texture of 750$^{\circ}C$ annealed sheets was similar to the cold rolling texture. The major preferred orientations of the 950$^{\circ}C$ annealed specimens were {112}<110> and {001}<110>. The formation of fine and closely spaced annealing twins in the specimen annealed at 1150$^{\circ}C$ led to the randomization of the annealing texture.

• Journal of The Korean Astronomical Society
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• v.40 no.4
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• pp.113-118
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• 2007

Recently far infra-red (FIR) polarization of the $850{\mu}m$ continuum emission from T Tauri disks has been detected. The observed degree of polarization is around 3 %. Since thermal emission from dust grains dominates the spectral energy distribution at the FIR regime, dust grains might be the cause of the polarization. We explore alignment of dust grains by radiative torque in T Tauri disks and provide predictions for polarized emission for disks viewed at different wavelengths and viewing angles. In the presence of magnetic field, these aligned grains produce polarized emission in infrared wavelengths. When we take a Mathis-Rumpl-Nordsieck-type distribution with maximum grain size of $500-1000{\mu}m$, the degree of polarization is around 2-3 % level at wavelengths larger than ${\sim}100{\mu}m$. Our study indicates that multifrequency infrared polarimetric studies of protostellar disks can provide good insights into the details of their magnetic structure.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.350-353
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• 2005

Microstructures according to experimental conditions (pouring temperature, stirring current and stirring time) and hardness according to aging time were investigated for A356 cast aluminum alloy and 7075 wrought aluminum alloy. In pouring temperature control, grains became larger and non-uniform at high temperature, however dendritic shapes were shown at lower temperature. In stirring current control, dendritic grains were not destroyed enough at lower current, however fine grains were agglomerated at higher current. And, in stirring time control, grains were more globular but grew larger and larger with the stirring time increasing.

• KOMUNHWA
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• no.57
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• pp.25-39
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• 2001

Carbonized wheat(Triticum aestivum), barley(Horudeum vulgare) and rice (Oryza sativa) grams were excavated at the AD 3C. old site in Nook-Do Kyungsang-South province. By the sieve floating method 180 grains of wheat, 4 grains of barley and 6 grains of ric

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04a
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• pp.14-16
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• 2002

Melting and re-solidification nature of $SmBa_2Cu_3O_{7-y}$ (Sm123) grains in Ba-Cu-O (Ba:Cu=3:5) liquid containing 0.7 at.% yttrium were investigated at the temperature lower than its melt point. When Sm123 grains/liquid powder compacts were heated to a temperature between two melting points of Ba-Cu-O liquid ($1000^{\circ}C$) and a Sm123 phase ($1060^{\circ}C$) and held at this temperature for appropriate time, Sm123 grains melted partly in the liquid that was formed by melting of the liquid-forming powder. During subsequent slow cooling, (Sm,Y)$Ba_2Cu_3O_{7-y}$ solidified at the outer parts of the unmelted Sm12 grains, which is distinguished from the core regions by lower $Sm_2BaCuO_5$ (211) density.

• Mycobiology
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• v.31 no.4
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• pp.183-190
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• 2003

Five cereal grains(wheat, barley, rice, maize and sorghum) were collected from three Egyptian provinces known to be grain producers(Daqahlia, Gharbia and Kafer el-Sheikh). Two species of Alternaria(A. raphani and A. tenusinae); two species of Aspergillus(A. flavus and A. niger); one species of Cunninghamella(C. elegans); one Dreschslera species(D. myakt); three Fusarium species(F. graminearum, F. moniliform and F. solani); one Rhizopus species(R. stolonifer) and two species of Penicillium(P. digitatum and P. notatum) were isolated from the grains. The densities of these fungi and their frequencies of occurrence have been investigated. All the fungal isolates were tested for the production of toxic metabolites in culture media and the percentages of toxigenic isolates were calculated. The biological assay of the toxigenic fungal isolates showed significant variations in toxigenic activity. Thin layer chromatography revealed that the most active isolate produces moniliformin in culture media. The effect of culture conditions on the production of moniliformin was studied.

• Journal of the Korean Ceramic Society
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• v.36 no.8
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• pp.799-804
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• 1999

Composites of SiC-Si3N4 consisted of uniformly distributed elongated $\beta$-Si3N4 grains and equiaxed $\beta$-SiC grains were fabricated with $\beta$-SiC,. $\alpha$-Si3N4 Al2O3 and Y2O3 powders. By hot-pressing and subsequent annelaing elongated $\beta$-Si3N4 grains were grown via$\alpha$longrightarrow$\beta$ phase transformation and equiaxed $\beta$-Si3N4 composites increased with increasing the Si3N4 content owing to the reduced defect size and enhanced crack deflection by elongated $\beta$-Si3N4 grains and the grain boundary strengthening by nitrogen incorporation. Typical flexural strength and fracture toughness of SiC-40 wt% Si3N4 composites were 783 MPa and 4.2 MPa.m1/2 respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.2
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• pp.153-158
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• 2010

The crystallization of FePt/MgO(001) magnetic thin films of various thicknesses has been studied using synchrotron x-ray scattering, atomic force microscope, and vibrating sample magnetometer. In film with a 499-$\AA$-thick, face-centered tetragonal, ordered FePt phase was dominantly crystallized into perpendicular (001) grains keeping the magnetically easy c-axis normal to the film plane during annealing. In film with a 816-$\AA$-thick, however, longitudinal (110) grains keeping the c-axis parallel to the film plane were grown on top of the perpendicular (001) grains. The behavior of the magnetic properties was consistent with the thickness dependence of the crystallization. We attribute the thickness dependence of the crystallization to the substrate effect, which prefers the growth of the c-axis oriented perpendicular grains near the film/substrate interfacial area.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.70-71
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• 2006

Growth behavior and kinetics of grains in a liquid matrix has been studied by computer simulation for various physical and processing conditions. The kinetics of growing and dissolving grains were considered to follow those of single crystals in a matrix. Depending on the shape of crystals, rounded or faceted, different kinetic equations were adopted for growing grains and an identical equation for dissolving grains. Effects of such critical parameters as step free energy, temperature, and liquid volume fraction were evaluated.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.404-407
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• 1995

Magnetic properties of model exchange-spring magnets, which are composed of magnetically soft and hard grains, were calculated by means of computer simulation. The dependence of the magnetic properties on the strength of intergrain exchange interaction and the amount of soft grains was studied. The existence of soft grains enhanced the remanence remarkably, and the remanence over $0.8M_{s}$ was obtained in the model magnets containing 25% or more soft grains by volume. The calculated coercivity vs. the strength of the exchange interaction curves showed a peak at a critical strength of the exchange interaction, although the remanence increased monotonously with increase in the strength of the exchange interaction. Thus the maximum energy product also reached a peak around the same critical strength. The calculated maximum energy product exceeded $300kJ/m^{3}$ when the magnet is assumed to be composed of $Fe_{3}B$ and $Nd_{2}Fe_{14}B$.