• Korean Journal of Materials Research
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• v.14 no.1
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• pp.28-34
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• 2004

IN 738LC, the major material for gas-turbine for power generation, was heat treated at $750^{\circ}C$, $850^{\circ}C$, $950^{\circ}C$ for 1000, 2000, and 4000 hrs and the microstructural evolution and mechanical properties were examined using optical microscope, XRD, SEM/EDS. The results showed ${\gamma}$', the main strengthening elements in this alloy, was about 300 nm in size and was about 56% by area fraction in as-cast samples. The area fraction of ${\gamma}$' peaked at 2000 hours at $750^{\circ}C$. The average diameter of the ${\gamma}$' which was about 300 nm at ascast specimen increased to about 1 $\mu\textrm{m}$ after heat treatment at $950^{\circ}C$ for 4000 hrs. Carbides were formed at dendrite, cell or grain boundaries which was ascribed to the segregation caused by solute redistribution during solidification. It was found that MC type carbides formed at low temperature, whereas carbides of $M_{23}$ /$C_{ 6}$/ type formed at higher temperature or at longer degradation. The hardness and impact energy decreased as the heat treatment temperature or time of retention increased, which was inaccrodance with the area fraction of ${\gamma}$'.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.1
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• pp.1-11
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• 1988

Some promising design criteria for the construction of artificial beaches are presented. Based on the result of visitor's enquete and field observations, the degree of satisfaction for some parameters such as wave height, water and air temperature and quality of sediments are obtained. Correlations between these parameters and the degree of satisfaction are also derived and discussed. From the study, the desirable design conditions for artificial beaches with the degree of satisfaction over 70% are proposed as; the minimum comfortable utilization area per capita is found to be approximately $10m^2$, maximum mean wave height 0.7m, the lowest water temperature $22^{\circ}C$, average diameter of sands 0.5mm approximately with identical grain size and roundness, and the foreshore slope less than 1 : 20.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.5
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• pp.210-216
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• 2007

Porous nickel membrane far high precision gas filter was prepared by in-situ reduced/sintered process of NiO with an addition of polymer(PMMA; polymethyl methacrylate). It showed that the porosity of Ni membrane was approximately 52%. It is similar to metal membrane which prepared using metal fiber as raw materials. The average pore diameter and porosity of Ni membrane increased as content of added polymer and decreased as elevating reduced/sintered temperature from $800^{\circ}C$ to $1000^{\circ}C$. Increase of porosity at $800^{\circ}C$ was associated with surface diffusion mechanism that leads to initial sintering, while decrease of porosity at $1000^{\circ}C$ was associated with lattice diffusion and grain boundary diffusion.

• Korean Journal of Medicinal Crop Science
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• v.18 no.1
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• pp.22-27
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• 2010

This study was carried out to investigate the physicochemical characteristics of 3-year-old ginseng (for Samgyetang product) cultured by various seeding density in direct-sowing culture. Ginsengs were cultured by the seeding density, 275, 300, 330 352 and 396 seeds per Kan, $180{\times}90cm$ area. Survived rate (82.1%) were the highest in plot of 352 seeds sowed, length and leaf width were high in plot of 300 and 352 seeds. Root yield grain was increased with increase of the seeding density in direct-sowing culture except 352 seeds sowed. Average root weight and diameter were the highest in plot of 352 seeds sowed, 31.6 g and 18.4 mm, respectively. Crude saponin and each ginsenosides content were the highest in plot of 275 seeds sowed. Rg1 content was decreased, Rc and Rb2 content were increased with increase of the seeding density. Total soluble sugar content was the highest in plot of 330 seeds sowed and the lowest in plot of 396 seeds sowed, and oligo- and disaccaride content were high in plot of 330 and 352 seeds sowed. Reological characteristics of ginsengs cultivated according to various seeding density, hardness and springness were high and maximum fracture force was low with decrease of the seeding quantity.

• Korean Journal of Materials Research
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• v.31 no.12
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• pp.657-664
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• 2021

To build a highly active photocatalytic system with high efficiency and low cast of TiO₂, we report a facile hydrothermal technique to synthesize Ag₂Se-nanoparticle-modified TiO₂ composites. The physical characteristics of these samples are analyzed by X-ray diffraction, scanning electron microscopy with energy dispersive X-ray analysis, transmission electron microscopy and BET analysis. The XRD and TEM results show us that TiO₂ is coupled with small sized Ag₂Se nanoplate, which has an average grain size of about 30 nm in diameter. The agglomeration of Ag₂Se nanoparticles is improved by the hydrothermal process, with dispersion improvement of the Ag₂Se@TiO₂ nanocomposite. Texbrite BA-L is selected as a simulated dye to study the photodegradation behavior of as-prepared samples under visible light radiation. A significant enhancement of about two times the photodegradation rate is observed for the Ag₂Se@TiO₂ nanocomposite compared with the control sample P25 and as-prepared TiO₂. Long-term stability of Ag₂Se@TiO₂ is observed via ten iterations of recycling experiments under visible light irradiation.

• Korean Journal of Medicinal Crop Science
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• v.12 no.3
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• pp.219-225
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• 2004

This study was conducted to evaluate growth and yield characteristics and the contribution to the yield according to the emergent sequence of tiller under two planting density $(60{\times}15\;cm,\;60{\times}25\;cm)$ in Coix lachryma-jobi L. var. mayuen Stapf. The average culm length and number of rachillas of $60{\times}25\;cm$ planting density were 20 cm shorter and 4.7 higher, respectively, whereas seed setting position of $60{\times}25\;cm$ planting density was 1.7 nodes lower compared with $60{\times}15\;cm$ planting density. Culm length and culm diameter of each tiller became shorter and thinner as the tiller emerged later. Length of rachillas was longer, number of grains was higher and ripening rate was also higher in $60{\times}25\;cm$ planting density than those of $60{\times}15\;cm$ planting density, whereas 100 grain weight in $60{\times}25\;cm$ planting density was lower by 0.5 g compared with $60{\times}15\;cm$ planting density. Length of rachillas and number of grains according to the emergent sequence of tiller were shown shorter and lower as the tiller emerged later. The highest number of bract was obtained from the main culm in both planting densities. 100 grain weight according to the emergent sequence of tiller became lower as the tiller emerged later in $60{\times}15\;cm$ planting density, but there was no clear tendency in $60{\times}25\;cm$ planting density. Among 8 tillers, 5th tiller and 4th tiller of main culm contributed 84.4% to the yield in $60{\times}15\;cm$ planting density, while it was 84.1% in $60{\times}25\;cm$ planting density. Analysis of path coefficient to grain yield showed that direct effect was the highest in the number of grain per tiller followed by in the 100 grain weight and in ripening rate.

• Korean Journal of Food Science and Technology
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• v.21 no.4
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• pp.521-527
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• 1989

This study was conducted to investigate the differneces in milling, physicochemical, rheological and end-product properties between Korean and American wheat cultivars. Also, rheological and bread baking properties of Korean wheat flour in blends with U.S. standard flour were investigated. The milling yield of Korean wheat rated 71.1% similar to 71.6% of U.S. wheat. The average AWRC 61.8% of the three Korean wheats ranked higher than the conventional value of 60% for classifying hard and soft wheat. The cookies made from Korean wheat flour showed comparatively good spread with diameter of 8.5-8.9 cm, and marked recommendable top grain score. The volume ranges 975-1175 cc of sponge cake made from all cultivars tested were lower about 4-26% than that of standard cake flour. especially, Wonkwang was selected as one which has special characteristics good for cookie and sponge cake. The volumes of breads from Korean wheat 리ours ranged 924-1020 cc, and Yongkwang of 1020cc marked the most appropriate characteristics for bread-making among the tested wheats. The proper blending ratio of Korean wheat flour to U.S. bread standard flour was revealed 30% in bread-making.

• Korean Journal of Food Science and Technology
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• v.39 no.4
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• pp.412-418
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• 2007

The physicochemical properties and mixograph characteristics of soft white winter (SWW) and club wheat, as well as their product potentiality, were investigated. There were no significant differences between the SWW wheat and club wheat regarding their Single Kernel Characterization System (SKCS) properties. The straight-grade flour yield, break flour yield, ash content, and milling score of the SWW wheat were similar to those of the club wheat, and the straight-grade flour yield had a significant positive correlation to the break flour yield (r = 0.805**). The Rapid Visco-Analyzer (RVA) peak viscosity and swelling volume of the SWW wheat flour were very similar to those of the club wheat flour, and there was a significant positive correlation between the RVA peak viscosity and the swelling volume (r = 0.662**). The average mixograph absorption of the SWW wheat was higher than that of the club wheat. The club wheat resulted in a higher cookie diameter than the SWW wheat, but the difference was not significant. The sponge cake volume using the SWW wheat flour was higher than that with the club wheat flour. In addition, there was a significant correlation between the cookie diameter and the sponge cake volume (r = 0.745**).

• Journal of The Korean Society of Grassland and Forage Science
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• v.35 no.2
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• pp.105-111
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• 2015

"Seedgreen" (Secale cereal L.), a new rye cultivar was developed by National Institute of Crop Science (NICS), RDA in 2013. It was developed from an open pollination from within 10 rye varieties or lines including "Chochun" in 1995. The line "SR95POP-S1-140-9-1-3-7-5-3" was selected for its excellent agronomic appearance, and was placed in yield trials for three years from 2008 to 2010. The new cultivar was designated "Homil50" and was placed in regional yield trials at the five locations around Korea from 2011 to 2013, during which time the name "Seedgreen" was given. This cultivar is an erect plant type and of a long size, with a dark-green leaf color, a yellowish-white colored, medium-diameter culm, and a brown-colored, medium-size grain. The heading and maturation dates of Seedgreen were April 22 and June 16, which were 3 days and 2 days earlier than that of "Gogu", respectively. Seedgreen also showed better winter hardiness and a greater resistance to lodging and wet injury compared to those of the check cultivar. Over three years, the average dry matter yield of Seedgreen was 8.3 ton $ha^{-1}$ (fresh yield = 39.8 ton $ha^{-1}$), which was harvested in late April and was lower than that of the check cultivar Gogu. The seed productivity of Seedgreen was approximately 4 ton $ha^{-1}$, which was 16 % more than that of the check. Seedgreen was higher to than Gogu in term of protein content (10.5% and 9.7%, respectively), total digestible nutrients (TDN) (58.3% and 57%, respectively), and TDN yield $ha^{-1}$ (4.81 ton and 4.77 ton, respectively). This cultivar is recommended as a fall sowing crop in areas where the average daily minimum-mean temperatures are higher than $-12^{\circ}C$ in January, and as a winter crop for whole-crop forage before the planting of rice or green manure around Korea.

• Journal of The Korean Society of Grassland and Forage Science
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• v.37 no.1
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• pp.28-34
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• 2017

A new naked oat cultivar, 'Jungmo2005'(Avena nuda L.), was developed for food and forage use by National Institute of Crop Science, RDA in 2010. It was derived from a cross between $F_1$['Early80'/'Gwiri33'] and $F_1$['Early80'/'Gwiri23']. 'Early80', a covered oats, has early heading and high yielding, while 'Gwiri23' of covered type and 'Gwiri33' of naked type has early heading with large-size grain. 'Jungmo2005' has the characteristics of narrow and long leaves of pale green color, middle diameter culm of yellow color and medium grain of whitish yellow color. Cultivar 'Jungmo2005' had 2 days earlier heading date (May 9) than the check cultivar 'Seonyang' (May 11) in field condition. The 'Jungmo2005' showed better winter hardiness than that of the check cultivar, and similar to the check cultivar in respect to lodging resistance. The 'Jungmo2005' had 105 cm of culm length, 21.5 cm of spike length, 658 spikes per $m^2$, 82 grains per spike, 23.3 g of 1,000-grain weight, and 622 g of test weight. The grain yield of 'Jungmo2005' was averaged $3.38MT\;ha^{-1}$, which was 6% higher than that of the check. Average forage fresh and dry matter yield of 'Jungmo2005' harvested at milk-ripe stage were 44.8 and $12.6tone\;ha^{-1}$, respectively, compared with 47.5 and $12.5tone\;ha^{-1}$ of the check. The protein content of the 'Jungmo2005' was similar to the check (7.6% and 7.5%, respectively), while ADF (28.6%) and NDF (51.5%) were lower than the check (31.4% and 57.0%, respectively). TDN content and RFV were higher than those of the check (66.3%, 120.3 and 64.1, 105.2, respectively). 'Jungmo2005' is recommended for fall sowing cropping only in the south area where daily minimum mean temperatures are averaged higher than $-4^{\circ}C$ in January, and it should not be cultivated in mountain areas, where frost damages is likely to occur. The areas would do better only to sow in spring season.