• Journal of Korean Society of Forest Science
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• v.89 no.1
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• pp.18-23
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• 2000

Leaves of various, 3 to 5-year-old Quercus hybrids were intermediate in size between their parental species. The petiole length was the smallest in the hybrids of Q. dentata ${\times}$ Q. crispula $F_1$ and was intermediate in the hybrids of Q. aliena ${\times}$ Q. serrata $F_1$ and Q. dentata ${\times}$ Q. aliena $F_1$ between their parents. The number of serration in hybrids was close to their mother tree's in most of crossing combinations. The serration depth and the ratio between longitudinal and transverse length of leaves were intermediate between the values of their parental species.

• Korean Journal of Materials Research
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• v.28 no.6
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• pp.317-323
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• 2018

Crystal structure of the $L1_2$ type $(Al,X)_3Ti$ alloy (X = Cr,Cu) is analyzed by X-ray diffractometry and the nonuniform strain behavior at high temperature is investigated. The lattice constants for the $L1_2$ type $(Al,X)_3Ti$ alloys decrease in the order of the atomic number of the substituted atom X, and the hardness tends to increase. In a compressive test at around 473K for $Al_{67.5}Ti_{25}Cr_{7.5}$, $Al_{65}Ti_{25}Cr_{10}$ and $Al_{62.5}Ti_{25}Cu_{12.5}$ alloys, it is found that the stress-strain curves showed serration, and deformation rate dependence appeared. It is assumed that the generation of serration is due to dynamic strain aging caused by the diffusion of solute atoms. As a result, activation energy of 60-95 kJ/mol is obtained. This process does not require direct involvement. In order to investigate the generation of serrations in detail, compression tests are carried out under various conditions. As a result, in the strain rate range of this experiment, serration is found to occur after 470K at a certain critical strain. The critical strain increases as the strain rate increases at constant temperature, and the critical strain tends to decrease as temperature rises under constant strain rate. This tendency is common to all alloys produced. In the case of this alloy system, the serration at around 473K corresponds to the case in which the dislocation velocity is faster than the diffusion rate of interstitial solute atoms at low temperature.

• Journal of Forest and Environmental Science
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• v.15 no.1
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• pp.107-116
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• 1999

For the study on the variation of Pinus densiflora S. et Z. natural populations. 13 stands were selected in Kangwondo region in 1994. They were located in Hyoja-Dong, Chunchon-Si [plot 1]; Sinnam-Myun, lnje-Gun [plot 2]; Buk-Myun, lnje-Gun [plot 3]; Seo-Myun, Yangyang-Gun [plot 4 and 5]; Sonyang-Myun, Yangyang-Gun [plot 6]; Toseong-Myun, Goseong-Gun [plot 7]; Synrim-Myun, Wonju-Si [plot 8]; Dunnae-Myun, Hoengsong-Gun [plot 9]; Jinbu-Myun, Pyungchang-Gun [plot 10]; Sogumgang, Kangneung-Si [plot 11]; Seo-Myun, Ulchin-Gun [plot 12]; and Mitan- Myun, Pyungchang-Gun [plot 13]. The morphological characteristics of needles and cones were investigated for twenty individual trees from each population. The results are summarized as follows: 1. Among needle characteristics, length, the number of serration. and the number of stoma row were significantly different among populations and between individuals within a population. They were 69.3~91.9mm, 25.1~28.7 per 0.5cm, and 4.1~6.2 rows for abaxial side and 2.9~4.6 rows for adaxial side, respectively. 2. Among cone characters surveyed. length and diameter were significantly different among populations and between individuals within a population. They were 31.1~43.7mm and 20.0~24.1mm, respectively. 3. A highly positive correlation was observed between the number of stoma row of abaxial side and that of adaxial side. and between length and diameter of cone. But the number of serration was negatively correlated with all traits. 4. The distance from seashore was positively correlated with needle length and the number of serration, but negatively correlated with the number of stoma row and cone length. However, the altitude was positively correlated with the number of serration, but negatively correlated with the number of stoma row and cone length. 5. Cluster analysis using average linkage method for needle and cone characteristics showed two groups to Euclidean distance 1.0. They were group I consisting of plots 1, 8, 12, and 13 and group II of plots 2, 3, 4, 5, 6, 7, 9, 10, and 11. However, group II was divided again to Euclidean distance 0.8, that is a group including plots 2, 3, 9, and 11 and the other group comprising plots 4, 5, 6, 7, and 10.

• Korean Journal of Plant Resources
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• v.22 no.3
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• pp.266-272
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• 2009

Morphological characteristics of leaves, trichomes and acorns were investigated in 6-year-old artificial hybrids of Q. aliena ${\times}$ Q. mongolica var. crispula and Q. serrata ${\times}$ Q. mongolica var. crispula. Leaf shapes of Q. aliena ${\times}$ Q. mongolica var. crispula $F_{1}$ were obovate and resembled to that of Q. aliena. But several characters including the size of leaf and petiole and the shape of leaf base resembled to those of Q. mongolica var. crispula. In F1 hybrids, small stellate hairs distributed sparsely on the abaxial surface and their lay length was intermediate between both parents. There were no big differences on characters of nuts and cupules between both parents and $F_{1}$ hybrids. Leaf shapes of Q. serrata ${\times}$ Q. mongolica var. crispula $F_{1}$ were obovate-elliptic, and the leaf shape and leaf base and the length of petiole resembled to those of Q. mongolica var. crispula, but leaf size and serration resembled to those of Q. serrata. The number of serration in a leaf was intermediate between both parents. Small stellate hairs distributed sparsely and large single hairs were mixed on the reverse side of leaves. there were no big differences on the number and size of stellate hairs between $F_{1}$ hybrid and Q. serrata. It is able to distinguish $F_{1}$ hybrids from both parents by the size leaf size and shapes, leaf base and serration, petiole length and trichome type in the leaf.

• Wind and Structures
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• v.37 no.1
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• pp.15-23
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• 2023

The wake behavior of extended flat plate and serration in the trailing edge of S809 airfoil is presented in this experimental study using wind tunnel testing. The clustering of wind turbines in wind parks has recently been a pressing issue, due to the expected increase in power output and deciding the number of wind turbines to be installed. One of the prominent factors which influence the performance of the subsequent wind turbines is the downstream wake characteristics. A series of wind tunnel investigations were performed to assess the downstream near wake characteristics of the S809 airfoil at various angles of attack corresponding to the Reynolds Number Re = 2.02 × 105. These experimental results revealed the complex nature of the downstream near wake characteristics featuring substantial asymmetry arising out of the incoherent flow separations prevailing over the suction and the pressure sides of the airfoil. Based on the experimental results, it is found that the wake width and the downstream velocity ratio decrease with an increase in the angle of attack. Nonetheless, the dissipation length and downstream velocity ratio increases proportionally in the downstream direction. Additionally, attempts were made to understand the physical nature of the near wake characteristics at 1C, 2C, 3C and 4C downstream locations.

• The Korean Journal of Ecology
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• v.26 no.4
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• pp.173-180
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• 2003

To clarify whether the closely related species living in the same area is a population or populations ecologically, leaf morphology, specific leaf area, and fruit and seed production were studied in the natural group of sect. Pes-gallinaceua of Corydalis of Namhansansung area from 1999 to 2000. There were 352 plants in one square meter and total eight species or varieties were identified. Of the 352 plants, the number of C. turtschaninovii was the most with 103(29.3%), and that of C. ambigua was the next with 78(22.2%), and that of C. turtschaninovii var. fumariaefolia was the smallest with 9(2.6%). In the 28 plants having spotted leaves, central leaflet did not parted or again parted. The extent of partition with the plant was various from non-parted type to perfectly two-parted type (three leaflet). Between two extreme types, there were diverse types so that this character formed a gradient. The rate of length/breadth was in the range of 0.79~2.17. This character was related to the extent of leaflet partition but did not well expressed the distinguishing trait along a species. The number and the type of serration were diverse and there was no sharp borderline among the species or varieties. Ecological properties, specific leaf area, the number of fruit per plant, and the number of seed per fruit, varied with a wide range in a species or variety but differences between species or variety were not significant. Therefore, the Corydalis group studied was regarded as a population on the three criteria: (1) possibility of interbreeding, (2) continuity of leaf morphology, (3) irrelevance between character and species, (4) similarity of several ecological properties.

• Journal of Korean Society of Forest Science
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• v.22 no.1
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• pp.49-62
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• 1974

1. In the comparison of survival ratio among three different methods(bark graft, veneer graft, root graft), bark graft showed the highest survival ratio and root graft was the lowest. It was shown to be significant at the level of 5% in the analysis of variance for the results. It was able to be supposed that one of the main causes for the results was the different amounts of ferric tannic acid which was formated owing to the reaction of grafting knife with tannic acid oozing from cutting faces of the tree. In juvenile tissue graft, the survival ratio of inverted radicle graft was a little higher than that of juvenile stem graft, but there was no significant difference between two methods in analysis of variance. 2. The most hairs of chestnut tree leaves were recognized as stellates on the most part of leaves except for venation. The number of rays in the stellates was ranged from 4 to 8 generally. It was shown to be highly significant differences at the level of 1% among the each race growing at the similar environmental condition in the length of ray and the distributed ratio of the stellates having different ray number. 3. Excepting for the basal width of serration there were no significant differences between $Imakita_1$, $Imakita_2$ as well as between $Teteuchi_1$, $Teteuchi_2$ at the each point of experimental items in this study. Such results made this study more useful. 4. Among the races that were growing in the similar environmental condition, there were highly significant differences at the level of 1% in the length and the width of serration. 5. The rolling of hair, the angle of serration from the leaf margin, the existence of lateral vein in the serration, the intrusion of main vein into the serration and the width of main vein were observed to be somewhat useful as the subsidiary methods for the identification of chestnut races.

• Animal Systematics, Evolution and Diversity
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• v.28 no.4
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• pp.221-229
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• 2012

Paranebalia longipes (Willemoes-Suhm, 1875) is cosmopolitan and has been usually found in the algal and sponge debris on the sandy mud substrates. This species can be clearly distinguished from other species of Paranebalia by the presence of serration on posterior margin of pleopods, the number of articles on antennule and antenna, and number of teeth on flange of antennule fourth article. The genus Paranebalia is new to Korea. In this paper, we provide detail descriptions of the diagnostic characteristics and illustrations of the P. longipes. Additionally, type locality and world distribution of the genus Paranebalia are provided.

• Plant Resources
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• v.8 no.3
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• pp.244-249
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• 2005

The growth charateristics and karyotypes of Aster spathulifolius collected from 5 sites including coastal and island region on the Korean peninsula, were analysed. Several morphological characteristics of the plants such as leaf length, leaf width, top internode, medium internode, spike branching, flower diameter, number of petal, leaf color, leaf form, stem and leaf hair, viscosity, and serration of the plants were distinctly different depending on the native region from which they were collected. Karyotypic analysis showed that the chromosome number was all diploid (2n=18), with one pair of submetacentric satellite chromosomes. The chromosome composition included 7 pairs of metacentric chromosomes and 2 pairs of submetacentric chromosomes in all plants. However, chromosome order and the ranges of the chromosome lengths were a little different from plant to plant according to their native growing regions. The plants from Geoje-Do especially showed large differences in the chromosome lengths between the longest and the shortest compared to the plants from other places. This results provide important data to support the classification of the species into several sub-species.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.2
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• pp.102-112
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• 1997

This paper describes the method that can construct kinematically admissible velocity fields for forging of gear-like components which have tooth shape around the cylinder. The kinematically admissible velo- city fields for the various gear-like components, involute spur gear, trapezoidal spline, square spline, ser- ration and trochoidal gear, were constructed by pilling up the velocity components according to the shape of tooth and billet. The billets, of hollow and solid, were Al 2218 and 2024. To verify the method, the analyses and experiments were carried out and compared with each other. For analyses, the half pitches of com- ponents were divided into several deformation regions based on their tooth profile. A neutral surface was used to represent the inner flow of material during forging. Its location varied with the energy optimazation and its contour varied with the number of teeth. In experiment, the contour of material filling up the tooth zone is hyperbolic curve caused by the frictional drag on the interface of die-wall/workpiece but, in the analysis, it is an arc which retains the same contour during all forging operation.