• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.67-67
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• 2017

We developed the breeding materials with diverse grain size and shape in japonica rice. Grain size and shape are important factors affecting consumer preference and choice. However, most of Korean japonica rice cultivars have small, short, and round grain. To diversify the grain size and shape of japonica rice, we conducted the breeding program using donor parents, Jizi1560 and Jizi1581. Jizi1560 and Jizi1581 are japonica germplasm with extremely large grain. Four crosses between the each donor parents and high yielding japonica rice cultivars, Deuraechan and Boramchan, were constructed and then anther culture method was applied. We obtained 290 doubled-haploid (DH) lines with appropriated morphological traits and selected 91 DH lines with diverse grain size and shape. The grain related-traits of the selected DH lines showed a higher diversity when compared with 319 cultivars developed by NICS (264 japonica, 13 black, and 32 Tongil type cultivars). We designated the selected DH lines, four parents, and Daeripbyeo 1, large grain japonica cultivar, as the breeding materials for further analysis. The breeding materials were classified into five groups, A to E, based on the grain-related traits. Group A (including Jizi1581) and Group B (including Daeripbyeo 1) showed similar grain width, whereas Group A exhibited longer grain length and heavier grain weight. Group C (including Deuraechan and Boramchan) showed shorter and rounder grain shape and smaller grain size than any other groups. Group D including solely Jizi1560 had extremely large grain, such as the longest grain length, width, and thickness and heaviest grain weight. Group E including only two DH lines had long and slender grain shape, so that showed the highest ratio of length to width. The grain size and shape of the breeding materials exhibited beyond the characteristics of previously developed Korean japonica cultivars. The breeding materials will be applied in the breeding programs to diversify the grain size and shape of japonica rice.

• Journal of the Korean Ceramic Society
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• v.36 no.4
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• pp.372-379
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• 1999

Hihg-toughened ceria-stabilized tetragonal zirconia ceramics with irregular grain shape and undulated grain boundary was prepared by ceria doping. Irregularity of grain shapes was increased with the amount of doped ceria. But in case of the large amount of doped ceria grain boundary was migrated to the reverse direction of DIGM. Ceria-stabilized zirconia ceramics annealed at 1650$^{\circ}C$ for 2h after twice dippings into cerium nitrate solu-tion of 0.2M and sintering at 1500$^{\circ}C$ for 2h showed the highest grain boundary length with a value of 23.6$\mu\textrm{m}$ Ceria concentration difference between convex and concave sides in irregular grains was observed over 1 mol% but not observed in normal grains, Specimens with normal grain shape showed intergranular fracture mode whereas the specimens with irregular grain shape showed transgranular fracture mode.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2004.05a
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• pp.71-74
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• 2004

Recently, with the wide shortage of natural sand resources, it has been increasingly used the crushed sand. rushed sand is made by the process of crushing the rocks artificially, which has different particle properties compared with that of natural sand. Because such different panicle properties of crushed sand results in an undesirable effects of concrete. improvement technology for crushed sand particle properties like grain shape and fine particle needed during the manufacturing process. In this paper, improvement technology of grain shape and fine particle is reported. According to test results, adequate investment for manufacturing facilities like impact crusher and abrasion test machine is required to meet the advanced grain shape and grading of crushed sand. Based on the investigation of test result, mixing of natural land and crushed sand with given proportion can achieve the improvement of grain shape. For improving excessive fine panicle contents. current manufacturing system also can enhance the existing technology for fine particle without additional investment. It can be concluded that adequate investment and research can improve the quality of crushed sand.

• Journal of the Korea Concrete Institute
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• v.12 no.4
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• pp.103-111
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• 2000

The influence of the improvement of grain shape of the coarse aggregate to the unit powder content of concrete and the fine aggregate ratio for the increase of the flowability and segregation resistance of high performance concrete was examined. According to the experimental results, flowability and compacting of concrete presents best states in the S/a which has the smallest 패야 ratio. The coarse aggregate after improvement of grain shape, that has changed from the 0.68 of spherical rate of disk shape to 0.73, led fine aggregate ratio to be down 6% (i.e from 47% to 41%). The improvement of grain shape of the coarse aggregate also led the lowest unit powder content to be down 60kg/㎥ (ie from 530kg/㎥ to 470kg/㎥). And approximate 10% of unit water content has been reduced as unit powder content was down. However, the compressive strength after the improvement of grain shape of the coarse aggregate decreased to 5% due to decrease of adhesiveness of the aggregate and cement paste.

• Journal of the Korean Ceramic Society
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• v.43 no.11 s.294
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• pp.728-733
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• 2006

The equilibrium or growth shape of ceramic materials is classified largely into two categories according to the thermodynamic conditions imposed. One is a polyhedral shape where the surface free energy is anisotropic, and the other a spherical shape where the surface free energy is isotropic. In the case of grains with a polyhedral shape of anisotropic surface free energy, socalled abnormal grain growth usually takes place due to a significant energy barrier for a growth unit to be attached to the crystal surface. In the case of grains with a spherical shape of isotropic surface free energy, however, normal grain growth with a uniform size distribution takes place. In this contribution, the state-of-the-art of our current understanding of the relationship between the crystal shape and the microstructure evolution during the sintering of ceramic materials in the presence of a liquid phase was discussed.

• Journal of Powder Materials
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• v.13 no.2 s.55
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• pp.119-123
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• 2006

The grain growth behavior of $0.95Na_{1/2}Bi_{1/2}TiO_{3}-0.05BaTiO_{3}$ (NBT-5BT) has been investigated with respect to the grain shape. The powder compacts of NBT-5BT were sintered at 1200 for various times. The corresponding equilibrium shape was a round-edged cube with flat {100}-faces. Abnormal grains were not observed in the specimens sintered for 1 to 12 h but abnormal grains appeared when sintered for 24 h. Before the formation of abnormal grains, a valley was observed in the measured grain size distribution of NBT-5BT, showing that the grain size distribution was a combination of two unimodal distributions. The present result suggests that the grain growth in NBT-5BT was governed by the growth of facet planes which would occur via 2-dimansional nucleation and growth.

• Journal of the Korean Society for Heat Treatment
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• v.3 no.1
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• pp.34-41
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• 1990

Effects of grain size and cold rolling degree on shape memory ability and transformation temperature were studied in Fe-35% Mn-6% Si shape memory alloy. Md point of the alloy was determined by variation of yield stress with test temperature. The Md point measured in this way was linearly increased with increasing grain size. Shape memory ability of the alloy was decreased with increasing grain size, showing a minimum value at around $63{\mu}m$, and then increased with increasing grain size. From this result, it was concluded that the shape memory ability in the grain size smaller than a critical value is controlled by amount of retained ${\gamma}$ and prior ${\varepsilon}$ phase, but that the shape memory ability in the grain size greater than the critical value is mainly dominated by grain boundary area in unit volume of parent phase. The shape memory ability was decreased with increasing deformation degree. This was because the ${\gamma}$ content being available for the formation of ${\varepsilon}$ martensite during bending was decreased with increasing deformation degree.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.21.2-274
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• 1999

This study aims to examine the influence of the unit powder content of concrete and the fine aggregate ration of high flowing concrete after the improvement of grain shape of the coarse aggregate. According to the experimental results, flowbility and compating of concrete presents the best states in the S/a which has the smallest void ratio. The coarse aggregate after improvement of grain shape has been changed from 0.68 circular ratio of disc shape to 0.73 circular shape. It lead to be down 6% of fine aggregate ratio (from 47% to 41%), which is satisfactory to compacting. Also, the improvement of grain shape of the coarse aggregate lead the lowest unit powder content to be down 60kg/㎥ from (530kg/㎥ to 470kg/㎥). And about 11% unit water content can be reduced as unit powder conent is down.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.4
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• pp.303-313
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• 2020

Rice grain shape is one of the key components of grain yield and market value. An understanding of the genetic basis of the variation in grain shape could be used to improve grain shape. In this study, we developed a total of 265 F₂ individuals derived from a cross between japonica cultivars (Josaeng-jado and Langi) and used this population for quantitative trait locus (QLT) analysis. Correlation analysis was performed to identify relationships between grain traits (GL: grain length, GW: grain width, L/W: ratio of length to width, TGW: 1,000 grain weight). The grain shape was positively correlated with GL and TGW, and negatively correlated with GW. In QTL analysis associated with grain shape, one QTL for GL, qGL5, detected on chromosome 5, explained 20.3% of the phenotypic variation (PV), while two QTLs, qGW5 (PV=36.1) and qGW7 (PV=26.1), for GW were identified on chromosomes 5 and 7, respectively. Evaluation of the effects of each of the QTLs on the grain shape in the population showed a significant difference in the grain size in positive lines compared with the lines without the QTLs. According to the QTL combination of the allelic-types, the grain shape of the tested lines varied from semi-round type to long spindle-shaped type. The results of this study extend our knowledge about the genetic pool governing the diversity of grain shape in japonica cultivars and could be used to improve the grain shape of this species through marker-assisted selective breeding in Korea.

• Journal of The Geomorphological Association of Korea
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• v.26 no.1
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• pp.15-26
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• 2019

In this study, we investigated the grain size, lithological type, and shape of coarse bed materials in the upper and middle reaches of Gongneungcheon River. For this purpose, 11 sampling points were selected along the river. For 100 samples of the coarse bed materials at each point, three axes (long, intermediate, and short) of samples were measured, and their lithological types were also identified. By measuring grain size, the sphericity and flatness of samples were calculated. Finally, every particle was classified into four shape categories: sphere, disc, blade and rod. We found that the grain size in incised meandering reach is the largest. This is mainly due to the supply of coarse materials from steep valley sides along the meandering channel. According to the lithological analysis, all samples were identified as granite, gneiss and schist, and quartz. The proportion of granite decreased, whereas the proportion of gneiss and schist increased downstream. These patterns indicate that the bedrock distribution within the study area accounts for the downstream lithological variation of coarse bed materials. With regard to the grain shape, sphericity gradually decreased while flatness gradually increased downstream. In the case of the shape classification, unlike the general downstream pattern of grain shape, the proportion of the sphere type decreased and the proportion of the blade type increased downstream. Such a reversal change in the downstream direction turns out to be determined by the lithology (such as foliation, bedding and the pattern of weathering) of coarse bed materials.