• Korean Journal of Materials Research
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• v.12 no.8
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• pp.634-640
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• 2002

To improve the ductility of mTEX>$(Al +12.5%Cu)<_3$Zr intermetallics, which are the potential high temperature structural materials, the mechanical alloying behavior, the effect of pressure and temperature on the $Ll_2$, phase formation and the behavior of the cold isostatic press and sintering were investigated. However mechanically alloyed A1$_3$Zr alloy have been known to have high mechanical strength even at high temperature, its workability was poor. A method of solution is refined grain size and phase transformation from $DO_{23}$ to $Ll_2$.$ Ll_2$ structure TEX>$(Al+12.5%Cu)<_3$Zr with nanocrystalline microstructure intermetallic powders where were prepared by mechanical alloying of elemental powders. Grain sizes of the as milled powders were less than 10nm (from transmission electron microscopy, TEM). Thermal analyses showed that $Ll_2$ structure was stable up to$ 800^{\circ}C$ for 1hour $(Al+ 12.5%Cu)<_3$Zr. $(Al+12.5%Cu)<_3$Zr has been consolidated by cold isostatic pressing (CIP 138, 207, 276, 414MPa) at room temperature and subsequent heat treatment at high temperatures where $Ll_2$ structure was stable under vacuum atmosphere. The results showed that 94.2% density of Ll$_2$ compacts was obtained for the (Al +12.5%Cu)$_3$Zr by sintering at 80$0^{\circ}C$ for 1hour (under CIPed 207MPa). This compact of the grain size was 40nm.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.3
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• pp.221-225
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• 2002

This study was conducted to identify the effects of slow release fertilizer (LCU) on ridge direct seeding on dry paddy of rice as an irrigation water-saying cultural system. During 1999-2000, a series of experiments was carried out at field (Chonbuk series) of the National Honam Agricultural Experiment Station, RDA using Dongjinbyeo. Plant height and culm length during the total growth duration were the longest and panicle umber per $m^2$ was the highest in 100% LCU application rate. Leaf area index and top dry weight were the highest in the 100% LCU application rate. They increased as more LCU was applied. Nitrogen uptake was the highest in 100% LCU application, and N use efficiency was the highest in LCU 60% + FP (fertilization at panicle formation stage) 20% application. Milled rice yield was 7% higher in 100% LCU application rate than that of conventional N application. Ripened grain rate and 1,000-grain weight of brown rice did not differ, but panicle number per $m^2$ and grain number per m2 were the highest at 100% LCU application.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.265-265
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• 2017

This study was carried out to develop rice variety integrated with rice bacterial blight resistance gene and to know the information of major agronomic traits of developed variety. Advanced backcross Lines 21 having Xa3 and Xa21 gene cross from japonica cultivar Hwanggeumnuri and indica variety IRBB21. Days after seeding and culm length of ABLs21 were 108 days (Aug. 16) and 76 cm, respectively. Ripened grain rates was 87.4 %, which was similar to the parents. 1000 grain weight of brown rice of ABLs21 was 21.4g, which was lower than the donor parent. Milled rice yield of ABLs21 was 532 kg/10a, which was smaller than recurrent parent and higher than the donor parent. Grain length/width ratio of brown rice was form of japonica with short-ellipse and glossiness of cooked rice has japonica trait. Head rice rate showed a large difference compare to the donor parent and similar to the recurrent parent. ABLs21 would be useful genetic resources for resistance breeding program against bacterial blight.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.1
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• pp.1-7
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• 2008

This experiment was carried out to evaluate the agronomic stability of North Korean rice varieties using the statistical model developed by Grafius, Finlay, and Ever hart. The lowest yearly variation based on coefficients of variation was found in Hannam 29 for number of panicles per hill, in Sijoong 9 for number of grains per panicle, in Pyeongyang 3 for ripened grain ratio, in Sijoong 16 for 1,000 grain weight, and in Yeomju 1 for grain yield. By Grafius's model, Pyeongbook 3, Weonsan 66 in early maturing groups and Seohaechalbyeo in medium maturing groups show stable for 3 years. Weonsan 66 in early maturing groups and Seohaechalbyeo in medium maturing groups were found to be highly stable as analyzed by both Finlay and Wilkinson's model and Everhart & Russell's model. With reference to three models, Weonsan 66 was highly stable for 3 years with showing more yield than Odaebyeo in early maturing groups while Seohaechalbyeo was highly stable for 3 years with showing high yield than Hwaseongbyeo in medium maturing groups above $5\;t\;ha^{-1}$ of milled rice respectively.

• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.485-492
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• 2012

Dense and single phase $BiFeO_3$ (BFO) ceramics were prepared using attrition milled calcined (coarse) powders of an average particle size of ${\approx}3{\mu}m$ by conventional sintering process. A relative density of ${\approx}96%$ with average grain size $7.3{\mu}m$ was obtained when the powder compacts were sintered at $850^{\circ}C$ even for a shorter duration of 10 min. In contrast, densification barely occurred at $800^{\circ}C$ for up to 12 h rather the microstruce showed the growth of abnormal grains. The grain growth behavior at different temperatures is discussed in terms of nonlinear growth rates with respect to the driving force. The sample sintered at $850^{\circ}C$ for 12 h showed enhanced electrical properties with leakage current density of $4{\times}10^{-7}A/cm^2$ at 1 kV/cm, remnant polarization $2P_r$ of $8{\mu}C/cm^2$ at 20 kV/cm, and minimal dissipation factor (tan ${\delta}$) of ~0.025 at $10^6$ Hz. These values are comparable to the previously reported values obtained using unconventional sintering techniques such as spark plasma sintering and rapid liquid phase sintering.

• Journal of Powder Materials
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• v.4 no.2
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• pp.122-132
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• 1997

Nanostructured(NS) W-Cu composite powders of about 20~30 nm grain size were synthesized by mechanical alloying. The properties of NS W-Cu powder and its sintering behavior were investigated. It was shown from X-ray diffraction and TEM analysis that the supersaturated solid solution of Cu in W was not formed by the mechanical alloying of mixed elemental powders, but the mixture of W and Cu particles with nanosize grains, i.e., the nanocomposite powder was attained. Nanocomposite W-20wt%Cu and W-30wt%Cu powders milled for 100 h were sintered to the relative density more than 96% and 98%, respectively, by sintering at 110$0^{\circ}C$ for 1 h in $H_2$. Such a high sinterability was attributed to the high homogeneous mixing and ultra-fine structure of W and Cu phases as well as activated sintering effect by impurity metal introduced during milling.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.549-552
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• 2002

$(SrBi_2Nb_2O_9)_{0.5}-(Bi_3TiNbO_9)_{0.5}$ ceramics were fabricated by the mixed-oxide method, and the structural and electrical properties with variation of ball-milling time were investigated. All SBN-BTN specimens showed the typical polycrystalline X-ray diffraction patterns without the presence of the second phase. The SBN-BTN specimen sintered at $1200^{\circ}C$ and ball-milled for 168h showed the average grain size of $16{\mu}m$. The dielectric constant and dielectric loss of the SBN-BTN specimen sintered at $1150^{\circ}C$ and ball-mill for 72h were 225, 0.4% at 1KHz, respectively.

• Journal of Biosystems Engineering
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• v.32 no.1 s.120
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• pp.1-5
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• 2007

This study was conducted to find out effects of abnormal kernels of 0 to 30% in brown rice on quality characteristics during milling using friction type test mill. The average hardness values of abnormal and normal brown rice kernels were 6.52 kg$_f$, 8.48 kg$_f$, respectively. According to the increase of abnormal kernels in brown rice, grain temperature, required electrical energy, the broken kernels ratio, and the weight of solid matter on the surface of milled rice were increased due to crush of the abnormal kernels during milling, which proves that abnormal kernels in brown rice should be removed before milling to improve milling characteristics.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.202-203
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• 2002

Ribbon type nanocrystalline alloy cores have shown excellent soft magnetic properties in the high frequency range because of small crystalline anisotropy and nearly zero magnetostriction[1]. In present, however ribbon alloys gives some limit in applications such as a large inductor and reactors of PFC circuit, which are required good DC bias property and low loss in the high frequency. Powder alloys with ultra fine grain structure can be an important way to overcome this kind of disadvantage, and to improve the high frequency soft magnetic properties in conventional metallic powder cores[2]. (omitted)

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.272-273
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• 2006

A new process of pulsed electric current sintering was developed. It combines compaction with activated sintering effectively and can manufacture bulky nano-crystalline materials very quickly. A nano-structured steel is obtained with high relative density and hardness by this process. The average grain size of iron matrix is 58nm and the carbide particulate size is less than 100 nm. The densification temperature of ball-milled powders is approximately $200^{\circ}C$ lower than that of blended powders. When the sintering temperature increases, the density of as-sintered specimen increases but the hardness of as-sintered specimen first increases and then decreases.