• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.631-632
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• 2006

Cr-C-Ni composites were synthesized in situ from elemental powders of Cr, Ni and C by high energy milling followed by reactive sintering. The milled powders with the grain size in nano-scale were pressed to compacts and sintered. During the following thermal treatment at first the chromium carbide was formed and then the $Cr_3C_2-Ni$ cermets were sintered in one cycle. The interface between the binder phase and the carbide grains of the in situ composite has a good bonding strength as it is not contaminated with oxidation films or other detrimental surface reactions.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.670-671
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• 2006

We report on the mechanical and structural properties of nanocrystalline 8% and 10% mol yttria stabilized zirconia (YSZ) obtained using mechanical alloying (MA). The as-milled powders show a body-centered cubic structure with grain sizes in the nanometer scale. After uniaxial pressing and sintering the compacts exhibit good mechanical properties. We discuss the correlation of these enhanced properties with the microstructural changes induced by heat treatment.

• Journal of Powder Materials
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• v.7 no.3
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• pp.149-153
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• 2000

In this study, the fabrication of $Al_2O_3$/5vol.%Cu nanocomposite and its mechanical property were discussed. The nanocomposite powders were produced by high energy ball milling of $Al_2O_3$ and Cu elemental powders. The ball-milled powders were sintered with Pulse Electric Current Sintering (PECS) facility. The relative densities of specimens sintered at $1200^{\circ}C$ and $1250^{\circ}C$ after soaking process at $900^{\circ}C$ were 96% and over 97%, respectively. The sintered microstructures were composed of $Al_2O_3$ matrix and the nano-sized Cu particles distributed on grain boundaries of $Al_2O_3$ matrix. The nanocomposite exhibited the enhanced fracture toughness compared with general monolithic $Al_2O_3$. The toughness increase was explained by the crack deflection and bridging by dispersed Cu particles.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.2
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• pp.79-83
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• 2020

A photoelectric grain color sorter is commonly used in postharvest technology to detect and separate grains considered to be of good quality from those of poor quality based on color. In this study, the milled rice of Haedamssal cultivated under early transplanting conditions was evaluated using the color sorting device. Rice was classified according to standard grades of 64% for grade A, 18% for grade B, and 17.2% for grade C. By head rice ratio analysis, the milled rice of Haedamssal was recorded a grade A of 72.9%, representing a 24.5% improvement compared to the 48.4% of original grains. However, the grades B and C of Haedamssal rice were lower than those of original rice. In addition, grade A whiteness of Haedamssal rice was 45.3, which was lower than that of original grains. The color affinity redness was significantly lower in Haedamssal rice than in the screening control. No significant difference was found in the amylose and protein contents of rice before and after selection by the grain color sorter. In contrast, grain viscosity analysis revealed an increase in peak and final viscosities, while the consistence viscosity increased in low grade levels. Our results suggest that the photoelectric grain color sorter could improve the head rice ratio and palatability of early transplanted Hadamssal rice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.spc1
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• pp.73-76
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• 2006

This study was carried out to investigate the change yield and grain quality in rice caused by damages of brown planthopper (Bph) on major agronomic traits at the ripening stage. A major agronomic traits such as culm length, panicle length, number of panicle and number of grain per panicles was no-significant difference compared hopperburn area (HBA) and moderately damaged area (MDA) by brown planthopper with non-damaged area (NDA). but, the ripeing ratio and yield in HBA and MDA was significantly decreased. The perfect rice of brown rice in HBA and MDA was also lowered than the NDA and the immatured grain among imperfect rice in damaged area by BPH was significantly increased than in the NDA. Among the traits related with palatability of cooked rice, the amylose content was not affected by damage of brown planthopper, whereas, the protein content was significantly increased in the HBA and MDA. additionally, Peak viscosity in HBA and MDA is lower than the NDA, and setback was increased. In most cases, there was negative on yield and grain quality by the damage of brown planthopper at the ripening stage. Thus, the rice product harvested in damaged area should be separated with that in non damaged area for grain market quality of milled rice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.26 no.2
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• pp.147-156
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• 1981

Most of the currently available rice threshers in Korea are of head-feeding type originally developed for threshing paddy at grain moisture content of 15 to 17% on wet basis. And prevailing rice harvesting system is swathing or cutting and bundling upright rice crop at a maturity stage of grain moisture content of ca. 28 to 20%, followed by transient natural drying in the field and threshing at grain moisture content of about 17%. The system often allows rather high field loss of rice both quantitatively and qualitatively. These necessitate use of a preharvest desiccant, and diquat has been registered recently as a rice desiccant. Aim of the present study is to determine the best time and rate of diquat application and to evaluate its utility as a rice desiccant under its optimal usage conditions in Korea. Diquat was not so effective for japonica rice varieties while it was very effective for the new varieties bred from indica x japonica crosses. The best time of application was the period from 2 days before to 3 days after physiological maturity of grain (moisture content of 28% w.b.) and the optimal rate was about 330g of diquat ion/ha. Applying diquat at the right time and rate dropped grain moisture to 15 to 16% (w.b.) within a week after treatment in contrast to that of 20 to 24% in untreated rice. Desiccation of rice crop with diquat resulted in 10 to 15% increase in grain resistance to shattering and significant reduction in percent green rice. However, there was no reduction in milled rice yield and percent whole kernel and was no change in the percent chalky rice and percent tinted rice. Diquat use appears highly desirable, if there is no residue problem which has not been studied in the present study.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.3
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• pp.193-203
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• 2019

The aim of this study was to analyze the relationship between rice yield and climate elements in Daegu (southern plain area) and Andong (inland mountainous area) regions. Over the past 20 years, rice yield has increased in both regions. The rice yield of middle and mid-late maturing cultivars in the recent 5 years increased by about 10% and 18%, respectively, compared to that produced in the early 2000s in the Daegu region. In the Andong region, the rice yield of mid-late maturing rice cultivars in the recent 5 years was higher by about 7% than that of the early 2000s. The number of panicles per hill and grain ripening rate significantly affected rice yield in mid-late maturing cultivars. In addition, the grain weight and grain ripening rate significantly affected rice production in middle maturing cultivars grown in the Daegu region. With regard to the middle maturing cultivars, the relationship between grain weight and rice yield had a positive significant correlation in both regions. To understand the effect of climate factors on rice yield, the milled rice yield of several rice cultivars produced over the past 20 years (1999-2018) at both locations, Daegu and Andong, were evaluated. The rice yields increased owing to long sunshine duration during the grain filling stage in the Daegu region. In Andong, rising maximum temperature during the vegetative stage increased rice yield of early and mid-late maturing cultivars. Long sunshine hours increased yield of mid-late maturing cultivars in both regions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.1
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• pp.61-67
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• 1997

This experiment was carried out from 1979 till 1983 to elucidate the underdrainage effect on soil salinity and growth of rice plastic underdrainage was established 5m and 8m intervals in April of 1979 and Jinjubyeo the medium maturing rice variety was transplanted by hand at late of May. The results are as follow; The desalination effect was higher in 5m interval underdrainage than 8m interval underdrainage and the salt content was lower than 0.3％ at 1 year after in 5m interval, 2 years after in 8m interval underdrainage and 3 years after at control. Farther the distance from underdrainage position, less the desalinization rate that desalinization was least at center part of the underdrainage position. Desalinization effect was highest 30cm of soil depth and decreased deeper than it. Shorter the underdrainage interval, more the panicle number, heavier 1, 000 grain weight and higher the milled rice yield. But the milled rice yield wasn't significantly different between the underdrainage interval from 3 years after underdrainage.

• Korean Journal of Food Science and Technology
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• v.27 no.4
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• pp.516-519
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• 1995

Seven Korean milled rice samples (5 Japonica, 1 Indica, 1 Commercial) were used to compare the quality of brewing adjunct with that of U.S. IR36(Indica) sample was classified as having higher amylose and protein content and lower starch content than Japonica samples. IR36 sample did not differ from Japonica samples in wort color, wort viscosity, soluble protein, percent extract and sugar composition when it was used as brewing adjunct. Korean milled rice samples did not differ from U.S. sample in soluble protein, wort pH, wort viscosity, but lower in percent extract.

• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.648-653
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• 2012

Hybridization of dense ceramic membranes for hydrogen separation with an electronically conductive metallic phase is normally utilized to enhance the hydrogen permeation flux and thereby to increase the production efficiency of hydrogen. In this study, we developed a nickel and proton conducting oxide ($BaCe_{0.9}Y_{0.1}O_{3-{\delta}}$: BCY) based cermet (ceramic-metal composites) membrane. Focused on the general criteria in that the hydrogen permeation properties of a cermet membrane depend on its microstructural features, such as the grain size and the homogeneity of the mix, we tried to optimize the microstructure of Ni-BCY cermets by controlling the fabrication condition. The Ni-BCY composite powder was synthesized via a solid-state reaction using $2NiCO_3{\cdot}3Ni(OH)_2{\cdot}4H_2O$, $BaCeO_3$, $CeO_2$ and $Y_2O_3$ as a starting material. To optimize the mixing scale and homogeneity of the composite powder, we employed a high-energy milling process. With this high-energy milled composite powder, we could fabricate a fine-grained dense membrane with an excellent level of mixing homogeneity. This controlled Ni-BCY cermet membrane showed higher hydrogen permeability compared to uncontrolled Ni-BCY cermets created with a conventionally ball-milled composite powder.