• 천문학논총
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• 제30권2호
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• pp.261-263
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• 2015

The metallicity distribution of globular clusters (GCs) provides a crucial clue for the star formation history of their host galaxy. With the assumption that GCs are generally old, GC colors have been used as a proxy for GC metallicities. Bimodal color distributions of GCs observed in most large galaxies have, for decades, been interpreted as bimodal metallicity distributions, indicating the presence of two populations within a galaxy. However, the conventional view has been challenged by a new theory that non-linear GC color-metallicity relations can cause a bimodal color distribution even from a single-peaked metallicity distribution. Using photometric and spectroscopic data of NGC 5128 GCs in combination with stellar population simulation models, we examine the effect of non-linearity in GC color-metallicity relations on transformation of the color distributions into the metallicity distributions. Although in some colors offsets are present between observations and models for the color-metallicity relations, their overall shape agrees well for various colors. After the offsets are corrected, the observed spectroscopic metallicity distribution is well reproduced via modeled color-metallicity relations from various color distributions having different morphologies. We discuss the implications of our results.

• The Plant Pathology Journal
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• 제36권6호
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• pp.628-636
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• 2020

Morphological (cyst shape, color, and sizes [length (L), maximum width (W), volume and "a" (L/W)]), structural (vulvar cone slope angle [VCSA], surface wrinkle [VCSW], cyst wall thickness, composition, and texture) and biological characteristics (fecundity, hatching, and emergence [number of second-stage juveniles (J2) from a cyst]) in preceding Heterodera glycines (Hg), currently-recorded H. sojae (Hs) and H. trifolii (Ht) were examined by microscopy. Cysts were lemon-shaped, indicating the genus is Heterodera except for Hs that formed frequently globular cysts with significantly flatter VCSA (102.2°) with smooth VCSW than Hg (50.6°) and Ht (82.0°), but not genus Globodera because of the presence of vulvar cone in Hs. Ht was significantly larger in all morphological characteristics than Hg and Hs, suggesting Ht may be diagnosed differentially by cyst sizes and also host plant preferences. Hs showed smaller "a" value with more globular shape and stronger structures with more thickened and strengthened collagen-like texture of cyst wall than Hg and Ht. This suggests Hs may be diagnosed differently by structural characteristics from the others, especially Hg with similar cyst sizes. There were no significant differences in emergence (inoculum potential) among cyst nematodes due to the offset of fecundity and hatching rate; however, the inoculum potential of Hs may be not so persistent as Hg and Ht in fields because of its lower fecundity and higher hatching rate (causing rapid inoculum loss) than the others. These characteristics of cysts provide information useful for simple and differential diagnoses and reliable management of cyst nematodes.

• 소성∙가공
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• 제11권2호
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• pp.123-131
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• 2002

The rheology process is net shape manufaturing technology to high of automobile part and improve the mechanical properties. For the rheology forming process, Phase and globular microstructure are very important. The equipments to make a rheology alloys with slurry statement have been introduced. Therefore, the Problems to Produce a rheology alloyas with continuous process had also been investigated to make Production in industries. The validity of the introduced rheology Process is investigated by comparing the reported thixoforming results. Therefore, the many advantage of rheology process to be reduced the reheating Process and billet fabrication method has been expressed in terms of mass production, in the future.

• Applied Microscopy
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• 제25권1호
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• pp.15-29
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• 1995

Legumin was purified from the endosperm cells of the ginseng seed and analyzed its characteristics. Distributional patterns of the legumin in the endosperm cells were identified using the immunocytochemical method. Legumin was glycoprotein composed of two subunits, molecular weights about 33,000 and 25,000 respectively. The molecular shape of purified legumin stained negatively seems to have hexagonal structure about 10 nm in size. It was localized at the rER, dictyosomes, and in the vacuoles at the early developing stage. Legumin was glycosylated in the dictyosomes and transported from the dictyosomes to the vacuoles. Legumin was accumulated into the central vacuole via the dictyosomes while the endosperm cells were developing. The armorphous proteins containing legumin were scattered randomly within the central vacuoles, which were aggregated together and became gradually spherical shape. Legumin was distributed within the globular protein bodies in the endosperm cells of matured seed. However legumin was not found in the globoids located in the protein bodies.

• 천문학회지
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• 제2권1호
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• pp.1-9
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• 1969

On the instantaneous tidal relaxation approximation, formulae are derived for the ellipticities and virial theorem of a slightly flattened homogeneous rotating cluster (the largest axis of the cluster is directed towards the Galactic center), in terms of the Galactic tidal force and the characteristic intrinsic plus orbital angular velocity. The expression for a purely tidally-determined ellipticity is identical to that for an incompressible fluid body of uniform density. Orbital motion generally contributes significantly to the shape of the cluster. The virial theorem is identical to that for an isolated cluster except that the gravitational potential energy is multiplied by (1-${\chi}$), where ${\chi}$ is a positive tidal correction term. To obtain the actual mass of a cluster, the virial theorem mass based on an isolated cluster should be multiplied by the factor 1/(1-${\chi}$). The formulae are applied to open star clusters, the globular cluster ${\omega}$ Centauri, and dwarf elliptical galaxies in the Local Group.

• 한국환경복원기술학회지
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• 제18권1호
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• pp.53-69
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• 2015

Plants and birds have symbiotic relationship as the birds eat the fruits and disperse its seeds from the different places. Because Brown-eared Bulbul eats various fruits, We investigated the fruits consumed by Brown-eared Bulbul and the distribution of these seeds. Surveys were conducted at several area throughout Jeju Island at least twice a month from 2013 to 2014. We identified the fruits consumed by Brown-eared Bulbul through observation, pictures and interviews from the local residents. Results showed that this species consumed fruits from 82 plant species, belonging to 38 plant families. Thirty nine percent(39%) of these plant species belong to the Rosaceae, Lauraceae, Moraceae, Aquifoliaceae and Vitaceae and 33 species were classified as warm-temperate and subtropical plant which is 40% of the total plant species consumed. Two feeding types, which were gulper type and pecking type were observed for the Brown-eared Bulbul. It was also observed that this species preferred eating fruits of gulping type compared to that of pecking type. The average size of the fruits consumed through gulping was $8.92{\pm}3.41mm$ while it was $45.25{\pm}26.67mm$ for the pecker type. This bird species also consumed more fruits with globular shape compared to those of fruits with ellipse shape. For the fruit color, red and black-colored fruits were more preferred than yellow-colored fruits by Brown-eared Bulbul. Eaten frequency varied from 0.04 to 0.58 and the 10 fruits species were eaten frequently by Brown-eared Bulbul. This study would provide information for the role of Brown-eared Bulbul in the ecosystem as a seed dispersal agent.

• 한국주조공학회지
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• 제28권3호
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• pp.129-135
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• 2008

The reheating stage of electromagnetically stirred Al billet is a critical factor in the thixoforming process. When reheated to the solid-liquid state, the microstructure evolves to a more globular and more homogeneous structure by a coarsening mechanism, the kinetics depending on the initial microstructure. Microstructural evolution has been characterized by conventional parameters (mean size of particle and shape factor) as a function of holding time in the solid-liquid state. The aim of this study is to report experimental results concerning microstructural evolution in the solid-liquid state of electromagnetically stirred Al billet. The material was elaborated in the form of continuously cast bars solidified with electromagnetic stirring to degenerate the dendritic structure. The choice of the reheating conditions is determined by a dendritic ripening and coalescence mechanism, involving variations of both the shape and size of the particles. The reheating time has to be long enough to allow a minimum degree of spheroidizing, but has to be limited as much as possible in order to avoid excessive ripening. The optimum microstructure was obtained at the reheating temperature of near $584^{\circ}C$ and the holding time of 5 min. The only means of combining high productivity with good casting quality was to use feedstock billets whose microstructure showed rapid transformation characteristics.

• Applied Biological Chemistry
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• 제39권5호
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• pp.379-383
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• 1996

조생종 쌀인 오대벼 품종을 대상으로 종자의 배유세포에 있는 전분복합체와 단백질체의 외부형태 및 미세 구조의 특징을 광학현미경과 전자현미경으로 관찰하였다. 배유세포는 긴 막대모양으로 세로 단면이 장방형 또는 마름모형을 하고 있고, 세포벽은 $0.5\;{\mu}m$의 두께로 균질한 막상 구조물로 이루어져 있다. 또한, 세포내에는 구형 또는 타원형의 전분복합체가 치밀하게 채워져 있으며, 직경이 $18{\sim}25\;{\mu}m$로 다양한 크기로 존재하였다. 전분복합체는 12면체 또는 14면체의 중앙 전분과립을 중심으로 약 $5\;{\mu}m$ 크기의 전분과립들이 동심원상으로 2 내지 3층으로 형성되어 있다. 배유세포에서 단백질체는 호분층에서 보다 아주 드물게 관찰되었지만, 전분복합체의 주변에 인립하여 산재하고 있다. 단백질체는 직경이 약 $3\;{\mu}m$로 구형 또는 난원형의 형태를 하고 있으며 미세구조적으로 중심부는 전자밀도가 높게, 한계막의 주변부는 비교적 전자밀도가 낮게 관찰되었다.

• Journal of the Korean Wood Science and Technology
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• 제16권2호
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• pp.90-97
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• 1988

The rate of utilization of the oak cork (bark of Quercus variabilis Blume) ranges only 40-50%. Therefore, this study was carried out to investigate the chemical properties of the oak cork for increasing the utility. 1) The contents of alkali extractives, organic solvent extractives and ash in the oak cork are similar to those of other barks, but hot and cold water extractives and lignin contents are lower than those of the wood. The carbohydrate (cellulose and hemicellulose) content of the oak cork is similar to that of other barks. The suberin contents in the first and the second bark of the oak cork are 34.8 and 32.2% respectively, in the dry weight. 2) Inorganic component contents of the first bark are similar to those of the second. The pH of the first and the second bark are 3.9 and 4.2%. The caloric values of the first and second bark are 6,263 Kcal/kg, and 5,828 Kcal/kg, respectively, and these caloric values are higher than those of other barks. The sclerencymatous cell content of the first bark which is related to the quality of the oak cork is lower than that of second bark, the contents of the sclerenchymatous cell and lignin show the positive correlation. 3) In the dimension of the cross sectioned cork cell, the first bark is bigger than that of the second. The shape of the cork cell is globular shape in the early bark and discoid shape in the late bark. The cross and the radial section are the same shape, but the tangential section shows difference from the other section.

• 한국세라믹학회지
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• 제53권4호
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• pp.444-449
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• 2016

Industrial by-products generated by integrated iron and steel manufacture cause environmental pollution. The by-products contain not only iron element but also harmful substances. Therefore, in view of to waste recycling and environmental preservation, production of sponge iron using the by-product is considered an effective recycling method. In this study, reduction efficiency of pellets from blast furnace dust was measured. Metallization was found to be increased, as $C/Fe_{total}$ ratio and reaction time were increased. The pellets were formed into a globular shape, and calcined for 60 minutes at $1100^{\circ}C$ in an electric furnace. Phase changes were analyzed using an X-ray diffractometer. Microstructures of the pellets were observed by a scanning electron microscope.