• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.2
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• pp.85-94
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• 2022

The mixed cropping system is a centuries-old cropping technique widely practiced in farmers' fields worldwide. Increased plant diversity enhances farmland biodiversity, which improves grain yield and quality. However, the effect of growing different rice cultivars simultaneously has rarely been investigated. In the present study, six glutinous rice cultivars were selected, and two mixture cultivation methods were determined according to plant height, grain yield, and color. Colored and glutinous rice are used for specific purposes by consumers because of their color and nutritive value. Six glutinous rice varieties, including aromatic and colored rice, were included in the combination interplanting trials. The results showed that, compared with the corresponding monocropping systems, almost all combinations of the mixed cropping systems had advantages in yield-related traits. Compared with monocropping systems, mixed cropping systems increased the number of panicles per plant and maturation rate by 20% and 10%, respectively. An increase of 18-20% grain yield was observed in mixed cropping plots compared with that in plots which grew only a single rice variety. Some rice varieties, such as green colored rice 'Nogwonchall' and black colored rice 'Chungpunghukhayangchall', exhibited 18-22% increased yield when they were planted in combinations. The high yields were primarily owing to improved light interception and reduced lodging, although other factors (for example, reduced severity of disease) may have also contributed.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.6
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• pp.537-544
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• 1993

Super-giant-embryo mutant line (Hwacheong-ge$^s$) with high nutritional quality was developed from Hwacheongbyeo, a Korean Japonica cultivar. Grain weight of brown rice of Hwacheong-ge$^s$ line was lighter than of Hwacheongbyeo. However, embryo dry weight of the line was 3.22 times heavier than that of Hwacheongbyeo on the single grain base. Hwacheong-ge$^s$ line showed higher protein(8.99%) than the original variety(7.39%), without changes in storage protein. In amino acid composition, lysine content was greatly increased in the mutant, while the contents of methionine, serine and tyrosine were slightly decreased as compared with the original one. Lipid content of Hwacheong-ge$^s$ line was 1.5 times higher compared with that of Hwacheongbyeo. The contents of Vitamin Bl, B2, and E(${\alpha}$-tocopherol) were also greatly increased in Hwacheong-ge$^s$line. The grain yields of the mutant lines ranged from 69.2% to 78.8% compared with that of Hwacheongbyeo, 556kg /10a. Most of the mutant lines of M4 generation were homogeneous for growth characters, and some of them seemed to be readily applicable for farmer's field.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.2
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• pp.227-232
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• 1983

Two single cross maize hybrids planted on May 4 and 25 and June 15, 1982 were grown at 40,000:55,000 70,000 and 85,000 plants per hectare to evaluate plant density effect on growth and grain yield at different planting dates. Two hybrids with different leaf angle (Suweon 19 with horizontal leaves and Suweon 58 with erect leaves) and the same maturity were used. The number of days from planting to silking varied from 74 to 58 days as planting was delayed from May 4 to June 15. However, growing degree days from planting to silking was about $810^{\circ}C$ regardless planting dates. Grain yields of two hybrids were significantly decreased as planting was delayed. The number of ears per 100 plants and the number of kernels per ear of two hybrids were linearly decreased with increasing plant density. The optimum plant density for Suweon 19 estimated by Duncan's method was about 55,000 plants hectare for May 4 and 25 plantings and decreased to 32,000 plants/hectare for June 15 planting. The optimum density for Suweon 58 was estimated to be about 71,000 plants/hectare for May 4 planting and 54,000 plants/hectare for May 25 planting, respectively.

• Korean Journal of Breeding Science
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• v.51 no.2
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• pp.105-109
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• 2019

'Hwangdaok', a new maize F1 hybrid (Zea mays L.), was developed by the maize breeding team at the National Institute of Crop Science (NICS), RDA in 2016. The high-yielding yellow dent hybrid named 'Hwangdaok' was obtained by crossing between two inbred lines, 'KS203' and 'KS190'. After advanced yield trial in Suwon in 2012, regional yield trial was subsequently carried out to evaluate the growth and yield of 'Hwangdaok' at three different locations from 2014 to 2016. The number of days to silking of 'Hwangdaok' is 76. The plant height is 262 cm and ear height ratio is 51%, which are similar to those of 'Jangdaok'. It has resistance to lodging. The number of ears per 100 plants is 95. The ear length is 21.3 cm and weight of 100 seeds is 34.7 g, similar to those of 'Jangdaok'. It has moderate resistance to southern leaf blight (Bipolaris maydis) and European corn borer (Ostrinia nubilalis). The grain yield (10 ton/ha) of 'Hwangdaok' is 6% higher than that of 'Jangdaok'. The seed production rate of 'Hwangdaok' is acceptable due to good synchronization of flowering period during crossing between the seed parent, KS203, and the pollen parent, KS190, in Yeongwol. F1 seed yield was 1.68 ton/ha. 'Hwangdaok' can be a suitable cultivar to plain areas in Korea. (Variety registration No. 7502).

• Korean Journal of Materials Research
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• v.34 no.4
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• pp.185-193
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• 2024

In this study, NASICON-type Li_1+XGa_XTi_2-X(PO₄)₃ (x = 0.1, 0.3 and 0.4) solid-state electrolytes for all-solid-state batteries were synthesized through the sol-gel method. In addition, the influence on the ion conductivity of solid-state electrolytes when partially substituted for Ti⁴⁺ (0.61Å) site to Ga³⁺ (0.62Å) of trivalent cations was investigated. The obtained precursor was heat treated at 450 ℃, and a single crystalline phase of Li_1+XGa_XTi_2-X(PO₄)₃ systems was obtained at a calcination temperature above 650 ℃. Additionally, the calcinated powders were pelletized and sintered at temperatures from 800 ℃ to 1,000 ℃ at 100 ℃ intervals. The synthesized powder and sintered bodies of Li_1+XGa_XTi_2-X(PO₄)₃ were characterized using TG-DTA, XRD, XPS and FE-SEM. The ionic conduction properties as solid-state electrolytes were investigated by AC impedance. As a result, Li_1+XGa_XTi_2-X(PO₄)₃ was successfully produced in all cases. However, a GaPO₄ impurity was formed due to the high sintering temperatures and high Ga content. The crystallinity of Li_1+XGa_XTi_2-X(PO₄)₃ increased with the sintering temperature as evidenced by FE-SEM observations, which demonstrated that the edges of the larger cube-shaped grains become sharper with increases in the sintering temperature. In samples with high sintering temperatures at 1,000 ℃ and high Ga content above 0.3, coarsening of grains occurred. This resulted in the formation of many grain boundaries, leading to low sinterability. These two factors, the impurity and grain boundary, have an enormous impact on the properties of Li_1+XGa_XTi_2-X(PO₄)₃. The Li_1.3Ga_0.3Ti_1.7(PO₄)₃ pellet sintered at 900 ℃ was denser than those sintered at other conditions, showing the highest total ion conductivity of 7.66 × 10^-5 S/cm at room temperature. The total activation energy of Li-ion transport for the Li_1.3Ga_0.3Ti_1.7(PO₄)₃ solid-state electrolyte was estimated to be as low as 0.36 eV. Although the Li_1+XGa_XTi_2-X(PO₄)₃ sintered at 1,000 ℃ had a relatively high apparent density, it had less total ionic conductivity due to an increase in the grain-boundary resistance with coarse grains.

• Geomechanics and Engineering
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• v.7 no.5
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• pp.477-493
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• 2014

This study examines the behaviour of single micropiles subjected to axial tension or compression load in collapsible loess under in-situ moisture content and saturated condition. Five tension loading tests and five compression loading tests on single micropiles were carried out at a typical loess site of the Loess Plateau in Northwest China. A series of laboratory tests, including grain size distribution, specific gravity, moisture content, Atterberg limits, density, granular components, shear strength, and collapse index, were carried out during the micropile loading tests to determine the values of soil parameters. The loess at the test site poses a severe collapse risk upon wetting. The tension or compression load-displacement curves of the micropiles in loess, under in-situ moisture content or saturated condition, can generally be simplified into three distinct regions: an initial linear, a curvilinear transition, and a final linear region, and the bearing capacity or failure load can be interpreted by the L1-L2 method as done in other studies. Micropiles in loess should be considered as frictional pile foundations though the tip resistances are about 10%-15% of the applied loads. Both the tension and compression capacities increase linearly with the ratio of the pile length to the shaft diameter, L/d. For micropiles in loess under in-situ moisture content, the interpreted failure loads or capacities under tension are 66%-87% of those under compression. However, the prewetting of the loess can lead to the reductions of 50% in the tensile bearing capacity and 70% in the compressive bearing capacity.

• Applied Biological Chemistry
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• v.23 no.3
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• pp.166-172
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• 1980

Starch granules of mungbean observed by microscope and scanning microscope were oval or round, $8{\sim}13{\mu}$ wide, and $18{\sim}30{\mu}m$ long. X-ray diffraction of the starch granules resulted weak crystallinity at $2{\theta}\;16.9^{\circ}$ The blue value of the starch was 0.36, amylose content 22.7%, alkali number 8.52, ferricyanide number 1.06, and water binding capacity of 81.6%. Swelling of the starch was negligible until $50^{\circ}C$, thereafter it increased rapidly. Optical transmittance of 0.3% starch suspension was increased rapidly from $65^{\circ}C$ and the gelatinization at $65{\sim}90^{\circ}C$ was of single stage. Amylogram patterns of the 6.7 and 8% starch solution were similar with no peak viscosity. The time constant for retrogradation of 40% starch gel stored at $21^{\circ}C$ was 1.99 days.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.10
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• pp.665-670
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• 2016

Prevailing dissemination of machine tools and cutting technology have caused drastic developments of high speed dry machining with work materials of high hardness, and demands on the high-hardness-materials with high efficiency have become increasingly important in terms of productivity, cost reduction, as well as environment-friendly issue. Addition of Si to TiAlN has been known to form nano-composite coating with higher hardness of over 30 GPa and oxidation temperature over $1,000^{\circ}C$. However, it is not easy to add Si to TiAlN by using conventional PVD technologies. Therefore, Ti-Al-Si-N have been prepared by hybrid process of PVD with multiple target sources or PVD combined with PECVD of Si source gas. In this study, a single composite target of Ti-Al-Si was prepared by powder metallurgy of MA (mechanical alloying) and SPS (spark plasma sintering). Properties of he resulting alloying targets were examined. They revealed a microstructure with micro-sized grain of about $1{\sim}5{\mu}m$, and all the elements were distributed homogeneously in the alloying target. Hardness of the Ti-Al-Si-N target was about 1,127 Hv. Thin films of Ti-Al-Si-N were prepared by unbalanced magnetron sputtering method by using the home-made Ti-Al-Si alloying target. Composition of the resulting thin film of Ti-Al-Si-N was almost the same with that of the target. The thin film of Ti-Al-Si-N showed a hardness of 35 GPa and friction coefficient of 0.66.

• Current Photovoltaic Research
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• v.1 no.2
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• pp.109-114
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• 2013

$Cu_2ZnSnS_4$ (CZTS) nanoparticles were synthesized by a solvothermal method using copper (II) acetate, zinc acetate, tin chloride, and sulfur in diethylenetriamine solvent. Binary sulfide particles such as CuS, ZnS, SnS, and $SnS_2$ were obtained at $180^{\circ}C$; single-phase CZTS nanoparticles were obtained at $280^{\circ}C$. CZTS nanoparticles with spherical shape and grain size of 40 to 60 nm were obtained at $280^{\circ}C$. In the middle of 180 and $280^{\circ}C$, CZTS and ZnS phases were found. The time variation of reaction at $280^{\circ}C$ revealed that an amorphous state formed first instead of binary phases and then the amorphous phase was converted to crystalline CZTS state; it is different reaction path way from conventional solid-state reaction path of which binary phases react to form CZTS. CZTS films deposited and annealed from single-phase nanoparticles showed porous microstructure and poor adhesion. This indicates that a combination of CZTS and other flux phase is necessary to have a dense film for device fabrication.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.55-55
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• 2009

FGB(Flexible Glasswool Backing) Submerged Arc Welding has been one of the main welding processes for one side butt welding in shipbuilding industries, which can efficiently improve the welding productivity by the addition of a supplementary filler metal into the molten weld pool. As recent ships have become larger in size, the application of high tensile and higher grade of steels has been continuously increased. Single pass FGB SA welding process accompanies such a high heat input when welding thick plates that the mechanical properties of weld metal can be dramatically degraded. This study has been performed in order to obtain high toughness and tensile properties of high heat input FGB SA welds, and to evaluate the effect of alloy elements on their mechanical properties. To complete welding 25mm-thick EH36 grade steel plate by single pass, 1.2mm diameter and 1.0mm long cut wires has been distributed in the groove before welding, and three different test coupons have been made using C-1.5%Mn, C-1.8%Mn-0.5%Mo, and C-1.4%Mn-1.7%Ni cut wires to investigate the influence of nickel(Ni) and molybdenum(Mo) on the mechanical properties of welds. Test results showed that the addition of Ni and Mo effectively promotes the formation of Acicular Ferrite(AF), while significantly reducing the amount of Grain Boundary Ferrite(GBF) in weld metal microstructures, which resulted in a beneficial effect on low temperature impact toughness and strength.