• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.6
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• pp.805-809
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• 1997

The influence of cool temperature occurred during the booting stage in 1993 on quality of rice grain was compared with that in favorable weather of 1994. The mean and minimum air temperatures during the reproductive growth stage at the paddy field of Jinbu Substation, National Crop Experiment Station were 2.2~7.4$^{\circ}C$ and 2.0~8.9$^{\circ}C$ lower respectively in 1993 compared to those of 1994. Grain fertility and brown rice yield were 11.8％ and 0.4t /ha, and 84.3％ and 5.5t /ha in 1993 and 1994, respectively. There was no difference in amylose content between two years. However, protein content of brown rice in 1994 were 1.6％ lower than that of 1993. There was no difference in alkali digestion value of milled rice between two years. Gel consistency of rice flour was 45mm in 1993 and 59mm in 1994. Amylogram characteristics of rice flour produced in 1993 showed lower peak hot, cool, and breakdown viscosities, and higher consistency and setback viscosities. The palatability of cooked rice by sensory panel test was considerably better in 1994 rice than in the rice of cool year.

• Korean Journal of Environmental Agriculture
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• v.30 no.4
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• pp.409-413
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• 2011

BACKGROUND: Cereals, especially rice is the staple food of oriental nations and because it is very important for Korean food, to determine the extent of nutrient losses due to milling, we analyzed the fatty acid using by GC-FID(Gas Chromatography-Flame Ionization Detector). Experimented rice cereals were rice, glutinous rice, Heuinchalssalbori, Seodunchalbori, Saessalbori, Keunalbori No.1, barnyard millet produced in Korea. METHODS AND RESULTS: After milling, the contents of fatty acids in the rice, glutinous rice, Heuinchalssalbori, and Seodunchalbori, Keunalbori No.1 rather decreased, but in the Saessalbori, and barnyard mille increased. Particularly, fatty acid content of the rice decreased from 24.8 mg/g to 6.4 mg/g, glutinous rice decreased from 29.4 mg/g to 11.7 mg/g after milling. There were also significant changes in the compositions of fatty acid among samples. Stearic acid ($C_{18:0}$) increased from 5% to 15%, but oleic acid ($C_{18:1}$) and linoleic acid ($C_{18:2}$) decreased in the rice after milling. CONCLUSION(s):In the brown rice, 11 different types of fatty acids were detected, and its highest content was found in grains. However, milled grain was observed only seven fatty acids in the case of rice. This result insisted that a portion of the lipid layer was significantly lost during the milling operation in rice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.1
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• pp.34-43
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• 1990

Six commerical rice varieties were cultivated and harvested at different locations in 1987 and 1988 to clarify the degree of locational variations. of several characteristics related to rice grain quality using the rice samples harvested from 8 to 20 locations for a variety each year. Locational variations of percent brown rice, percent milled rice, 1000-grain weight and amylose content were small, but whole grain rate, alkali digestibility, gel consistency, percent white-center and white-belly grain, degree of chalkiness and degree of translucency showed larger variations between locations. The degree of locational variation of sensory evaluation score for eating quality of cooked rice were varied from small to large along with rice variety used and year cultivated. Texture palatability index and stickiness of cooked rice among rheogram characteristics showed larger locational variations, but cohesiveness and springiness showed smaller variations between locations. Set back, break down and maximum viscosity showed larger locational variations among amylogram characteristics of rice flour. Special attention was given to a cultivated location, Anseong, because rice samples harvested at Anseong showed lower percent white-center and white-belly grain, and low set back and high break down in Chucheongbyeo, lower percent white-center and white-belly grain, higher texture palatability index and viscousness/hardness ratio, and low set back and high break down in Dongjinbyeo, higher texture palatability index, and low set back and high break down in Yongmunbyeo, lower percent white-center and white-belly grain in Sangpungbyeo, and low set back and high break down in Samkangbyeo. No other locations in this study produced rice samples showing wide acceptable quality-related characteristics except Anseong.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.214-220
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• 1999

Rice production in Korea has markedly increased during the last two decades due to newly developed high yielding varieties and improved production technology. This experiment was conducted to determine the potential of tropical japonica germplasm in enhancing the yield of temperate japonica. The yield performance of two tropical japonicas (IR 65597-29-3-2 and IR66154-52-1-2) and one temperate japonica (Dongjinbyeo) was compared at different plant densities and nitrogen levels under Korean environmental conditions. Although tropical japonicas showed low tillering habit and large panicles, they had similar leaf area index and dry weight at heading stage to Dongjinbyeo of the high tillering type indicating that there was not much difference between tropical and temperate japonica in terms of biomass production. The highest milled rice yield of 6.15 t/ha was obtained from Dongjinbyeo at a high nitrogen level with less planting density (220 kg N/ha and 30 $\times$ 15 cm). However, those of the two tropical japonicas were 5.36 t/ha at the condition of 165 kg N/ha and 30 x 10 cm planting density and 5.06 t/ha at the condition of 165kgN/ha and 15 x 15 cm planting density, respectively. Ripened grain of tropical japonicas ranged from 65 to 87%, while that Dongjinbyeo ranged from 82 to 97% under Korean conditions.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.05a
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• pp.47-55
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• 1999

The microstructure of Al 6061 powder milled from rapidly solidified flake and it's extrudate were investigated. The grain size of flake was about $0.8-1.5{\mu}m$ and the powder shape was spherical due to the milling condition. In the microstructure of extrudate, the unbinded powder boundary was found the front part of extrudate and all the macroscopic defects such as boundary defect, holes or cracks was not observed except the front part. It was found that the extrudate except 60cm of front part was useful part.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.5
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• pp.963-968
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• 1999

This study was tried to evaluate possibilities for discriminating the mixture degree of wheat flour from buckwheat products. Buckwheat was milled into four grades of powder, i.e. whole grain flour (WGF), inner layer flour(ILF), middle layer flour(MLF) and outer layer flour(OLF)), and these powders were mixed with wheat flour(WF) to make mixed samples. Ash, protein and fat contents of the buckwheat flours were high in the order of OLF=WGF>MLF>ILF. On the other hand, WF showed a similar content to OLF in ash and protein, and to ILF in fats. Potassium and magnesium contents were higher in all the buckwheat powder than in the wheat flour. Flavonoid contents were higher in order of OLF>WGF=MLF> ILF, but it was not in wheat flour. Although the reliable correlation between mix ratio and components, i.e. mag nesium or ash analyzed were found, it did not seem to reflect sufficiently the expected variations of contents of original material components. Also, compositions of commercial buckwheat products were analyzed to evaluate the mixed ratio of buckwheat flour and wheat flour. The results suggest that the components analyzed in this study as putative marker were not good in determining whether or how much buckwheat products contained wheat flour.

• Journal of Technologic Dentistry
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• v.42 no.2
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• pp.73-79
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• 2020

Purpose: The aim of this study was to investigate the influence of short and long duration sintering on microstructure and flexural strength of zirconia. Methods: To conduct three-point bending test, Zirconia specimens are milled according to ISO 6872 guidelines(N=18, n=9 per group). Two specimens group(n=8) is sintered for 10 hours(Standard schedule) and 3 hours(Speed schedule) at the peak temperature of 1550℃ with silicon carbide sintering furnace. Flexural strength of specimens are measured by instron. After coating each specimen(n=1), microstructure of specimens is observed using Scanning Electron Microscope(SEM). T-test was utilized to statistically assess the data. Results: The mean and standard deviation value of the flexural strength for standard schedule group are 578.15±57.48Mpa, that of speed schedule are 465.9±62.34Mpa. T-test showed significant differences in flexural strength between two zirconia specimen group which applied standard schedule and speed schedule respectively(p<0.05). Conclusion: The result of this study showed that the increase in sintering time led to increased grain size, and also to a positive effect on the flexural strength.

• Journal of the Korean Ceramic Society
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• v.49 no.1
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• pp.118-123
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• 2012

GDC20($Ce_{0.8}Gd_{0.2}O_{1.9}$) powder was synthesized from Ce and Gd nitrate solutions using ammonium carbonate($(NH_4)_2CO_3$) as a precipitant. Attrition-milling of the powder, which had been calcined at $700^{\circ}C$ for 4 h, decreased an average particle size of 2.2 ${\mu}m$ to 0.5 ${\mu}m$. The milled powder consisted of nano-sized spherical primary particles. Due to the excellent sinterability of the powder, sintering of the powder compacts for 4 h showed relative densities of 80% at 1000 $^{\circ}C$ and 96.5% at $1200^{\circ}C$, respectively. Densification was found to almost complete at $1300^{\circ}C$, resulting in a dense and homogeneous microstructure with a relative density of 99.5%. The grains of ~0.2 ${\mu}m$ in size at $1200^{\circ}C$ grew to ~1 ${\mu}m$ in size at $1300^{\circ}C$ as a result of a rapid grain growth.

• Journal of the Korean Society for Heat Treatment
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• v.26 no.6
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• pp.279-287
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• 2013

Oxide Dispersion Strengthened (ODS) Fe with $Al_2O_3$ dispersoid was successfully produced by reactive milling with a mixture of Fe, $Fe_3O_4$ (Magnetite), $Fe_2O_3$ (Hematite) and Al reactants at cryogenic temperature. The milled powders were consolidated by Vacuum Hot Press (HP) at 1323 K, and the consolidated materials were characterized by Transmission Electron Microscopy (TEM), Scanning Transmission Electron Microscopy (STEM), and Energy Dispersive Spectroscopy (EDS); the yield strength and the hardness of the consolidated materials were determined by compressive test and Vickers hardness test at room temperature. The grain size of the materials was estimated by X-ray Diffraction technique using the scherrer's formula. The TEM observations showed that the microstructure was comprised with a mixture of nanocrystalline Fe matrix and $Al_2O_3$ nano-dispersoids with a bimodal size distribution; the 0.2% off-set yield strength of the materials was as high as $758{\pm}29$ MPa and the Vickers hardness was $358{\pm}2$. The effect of the cryogenic milling and addition of extra Fe powder was discussed on the suppression of MSR (Mechanically induced Self-sustaining Reaction) for the desired microstructural evolution of ODS alloys.

• Journal of Powder Materials
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• v.27 no.3
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• pp.203-209
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• 2020

The automotive industry has focused on the development of metallic materials with high specific strength, which can meet both fuel economy and safety goals. Here, a new class of ultrafine-grained high-Mn steels containing nano-scale oxides is developed using powder metallurgy. First, high-energy mechanical milling is performed to dissolve alloying elements in Fe and reduce the grain size to the nanometer regime. Second, the ball-milled powder is consolidated using spark plasma sintering. During spark plasma sintering, nanoscale manganese oxides are generated in Fe-15Mn steels, while other nanoscale oxides (e.g., aluminum, silicon, titanium) are produced in Fe-15Mn-3Al-3Si and Fe-15Mn-3Ti steels. Finally, the phases and resulting hardness of a variety of high-Mn steels are compared. As a result, the sintered pallets exhibit superior hardness when elements with higher oxygen affinity are added; these elements attract oxygen from Mn and form nanoscale oxides that can greatly improve the strength of high-Mn steels.