• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.663-667
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• 2017

Fuel depletion and environmental problems due to the use of fossil fuels have been worsening of late, and the development of alternative energy sources is urgently required to address these problems. Among the alternative energy sources, wind energy is attracting much attention as a clean energy source, because it can be used unlimitedly without any pollutant emissions. In wind power generation, wind energy is converted to kinetic energy through rotor blades and this kinetic energy is converted to electric energy through generators. The design and manufacturing of the blades, which are the major parts of wind power generators, are very important, but South Korea still lacks the requisite basic data and key technologies and, therefore, has to import the blades from overseas. In this study, multi-layered blades capable of generating power at low wind speeds were applied to a small wind power generator and the output characteristics of the generator according to the wind speed and the number of blades were analyzed. As a result, at the maximum wind speed of 8m/s, the application of three blades achieved up to 33% and 18% higher generator output voltage, up to 33% and 15% higher generator output current, and up to 23% and 13% higher generator RPM than the application of one or two blades, respectively. In this study, the application of multi-layered blades to a small wind power generator was shown to improve the output characteristics of the generator and make the collection of electric energy possible even at low wind speeds.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.4
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• pp.329-335
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• 1988

[n order to find out the effects of nitrogen fertilizer and planting density on the leaf characteristics of high yielding cultivars of rice, Dongjin (Japonica type) and Samkang (Tongil type) were .grown under two nitrogen levels (150 and 250 kg N/ha) and three planting densities (30 ${\times}$ 15 cm, 30 ${\times}$ 12 cm, 30 ${\times}$ 9 cm. Leaf blade, sheath and dry weight of individual leaf. the number of green leaves after flowering were measured. Samkang was characterized as longer and wider leaf blade and sheath than Dongjin, less sensitive to nitrogen fertilizer and planting density, and higher proportions of green leaves after flowering. These morphological characteristics of Samkang caused an increase of grain yield by 30 per cent.

• Journal of Korean Society of Forest Science
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• v.88 no.1
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• pp.11-17
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• 1999

Morphological variations in leaves and leaf trichomes according to tree age were investigated for the identification of Quercus taxa at the different stages of development. The sizes of leaves from one-year-old seedlings of Q. serrata, Q. dentata, and Q. aliena were the smallest and increased with tree age. Blade length, blade width, petiole length, number of serration, and serration depth war also varied with tree age. Therefore, the examined taxa by the size and form of leaves were hardly identified at juvenile stages. The type, structure, and density of leaf trichomes of each species varied remarkably along with tree age. Three types of trichomes such as small stellate hairs, large stellate hairs, and long single hairs were observed on the abaxial side of leaves of Quercus taxa. In matured trees of Q. serrata both small stellate and long single hairs on leaves were observed. On the other hand large stellate hairs were found in leaves of Q. dentata. There were small stellate hairs in Q. aliens. In Q. mongolica var. crispula, no hair or small stellate hairs were occasionally found. It is possible to identify Q. serrata and Q. dentata by the characteristics of trichome even at two to three year old seedlings, while, it is difficult to tell Q. aliens and Q. mongolica var. crispula of seedlings from other taxa only by those of trichome.

• Journal of agriculture & life science
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• v.45 no.3
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• pp.25-33
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• 2011

This study was conducted to examine genetic variation on leaf characteristics of Machilus thunbergii populations. Ten populations were subjected to multivariate analysis for 9 characteristics of leaf morphology. Average length of leaf blade, leaf width, petiole length, vein number were 9.8cm, 4.0cm, 1.8cm, 8.4 respectively, while angle of leaf base and leaf apex were $67.9^{\circ}$ and $78^{\circ}$ respectively. The coefficient of variation (C.V.) on leaf characteristics was 20% which indicate similar features among the populations. Nested analysis showed statistically signigicant differences among populations as well as among individuals within populations. Genetic relationship between populations using complete linkage method showed four groups to Euclidean distance 1.2 and did not show a tendency to cluster into the same group. There were three principal components that had a meaningful eigenvalue over 1.0 among the 9 components. The explanatory power of the top three main components on the total variation was 92.8%. The first principal component (PC) was explained about 40.3% which is mainly correlated with maximum leaf width and the second PC was explained about 28.7% which is correlated with leaf blade length. The third PC was explained about 23.8% which is correlated with petiole length ($X_3$). These characters were important factors for analysis of the relationship among natural populations of M. thunbergii.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.3
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• pp.198-204
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• 2022

In this paper, the 5kW and 50kW vertical axis wind turbines were studied using the ANSYS flow analysis simulation program. The 5 kW vertical shaft wind turbine has 30 units of the number of main blades and sub-blades and the electrical characteristics were analyzed by changing the tip speed ratio (TSR) from 0.2 to 06. A 50kW vertical axis wind turbine was designed based on the electrical characteristics of a 5kW vertical axis wind turbine. When the tip speed ratio was 0.5, the 5 kW wind power generation showed the maximum output of 9.5 kW and the efficiency of 0.28. The calculation of the power current(Ip) and the power voltage(Ep) show that, as the tip speed ratio increases, the power current(Ip) decreases and the power voltage(Ep) increases. And even if the tip speed ratio was changed, 5kW wind power generation was measured for output of 5 kW or higher. When the tip speed ratio was changed from 0.3 to 0.6, 50 kW wind power generation was output more than 50 kW. When the tip speed ratio of 50kW wind power generation was 0.4, the output was 58.37 [kW] and the efficiency was 0.318, and it was confirmed that the proposed 50kW wind power generation satisfies the design conditions.

• Korean Journal of Environment and Ecology
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• v.26 no.3
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• pp.362-366
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• 2012

To explore on the defense strategies against hervivory of five Viburnum species, morphological characteristics of the leaf, leaf domatia structure and the number, herbivores insects and mites on the leaves, collected from the trees growing in Wonju-si, Pyeungchang-gun, Taebaek-si, Taean-gun, Bonghwa-gun, Sancheung-gun and Jinju-si were investigated from May 2009 to October 2011. Domatia of V. carlesii reveals pocket type, these of V. burejaeticum, V. dilatatum and V. wrightii reveal tuft type, and that of V. odoratissimum var. awabuki reveals pouch type. Domatia number per leaf proves the highest figures, 24.0/leaf for V. burejaeticum, and the lowest, 4.9/leaf for V. carlesii. Leaf surface trichomes of four Viburnum species except for V. odoratissimum var. awabuki are mainly stellate and hispid on the leaf-blade and veins, and dense stellate trichomes on the upper leaf surface of V. carlesii, V. burejaeticum, and V. dilatatum are observed till late growing season. Extrafloral nectaries(EFN) on the terminal veins of five Viburnum species are observed. Pellucid dots on the lower leaf surface of V. dilatatum and V. wrightii might be a good defense strategies against herbivores. We observe many predatory mites eating nectar on large pellucid dots of V. dilatatum. Predatory mites number per leaf proved highly significant differences among tree species, and mean of mites number was highest values 8.1/leaf for V. burejaeticum, and the lowest 2.6/leaf for V. odoratissimum var. awabuki. These results indicate that temperate broadleave trees develop various defense strategies against herbivores for survival. The more studies on the defense strategies against herbivores of tree species might be needed for sustainable forest ecosystem.

• Journal of Korean Society of Forest Science
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• v.43 no.1
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• pp.1-5
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• 1979

The arrangement and the number of vascular bundle in petiole were investigated with the hybrid Populus alba${\times}$P. glandulosa and both parents. 1. The variation in number and the arrangement of the vascular bundle in petiole were smaller at middle point than at nearer point to the leaf blade. 2. A small variation was found in the arrangement of the vascular bundle within a tree, same clone and same species. 3. Five shapes of vascular bundle were recognized in the $F_1$ hybrid, 26.7 per cent of the $F_1$ hybrid has the same shape with P. alba, 13.3 percent with P. glandulosa and 53.3 per cent of the $F_1$ hybrid shows the $F_1$ shape caused by hybridization. 4. The hybrid clones which show the same shape with P. alba are 66-20-1, 66-6-8, 65-22-11 and 64-6-44, hybrid clones of 65-95, 66-14-93 have the same shape with P. glandulosa. Hybrid clones of 66-15-3, 67-6-3, 65-22-4, 66-26-55, 68-1-54, 66-14-99, 65-29-19, 66-25-5 have $F_1$ shape.

• Korean Journal of Plant Taxonomy
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• v.35 no.4
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• pp.247-272
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• 2005

The Philadelphus schrenkii complex including P. schrenkii var. schrenkii, P. schrenkii var. jackii, P. schrenkii var. mandshuricus, P. tenuifolius, P. pekinensis, P. seoulensis, P. lasiogynus, and P. scaber, is distributed in China, Korea, japan, and far eastern Russia. Their taxonomic delimitations are obscure because quantitative characters, such as presence/absence and density of hair on leaf, petiole, style, disc, calyx-tube, and pedicel, are highly variable with no apparent characteristics that consistently distinguish from each other within the group. Thus, these morphological characters are reexamined using univariate analyses. P. pekinenesis is distinct from other taxa in having glabrous disk, calyx, pedicel, and leaf blade. In addition, the number of flowers in an inflorescence [(5)7-9(11) vs 5-7 in other taxa], smaller calyx tube [2.5-3 mm vs. (2.5)3-4(5.9) in other taxa], and slightly divided styles help distinguish P. pekinenesis from other related taxa in Korea. However, P. schrenkii var. schrenkii, P. schrenkii var. jackii, P. schrenkii var. mandshuricus, and P. lasiogynus show continuous variation in the pubescence of disk, calyx, pedicel, and leaf blade, and this may reflect a lack of divergence among them. Particular emphases are placed on P. tenuifolius and P. seoulensis, because of the high degree of morphological intergradation with respect to the degree of pubescence in disk, calyx, pedicel, and leaf blade and their inconsistent circumscription across various systematic treatments. P. scaber, distributed in the southern Korea, has often been treated as an independent species having exfoliated branchlets, distinct serrated leaf margin, and recurved styles. However, this current study suggests that P. scaber should be recognized as a form of P. tenuifolius because these distinguishing characters are continuous between P. tenuifolius and P. scaber. In geographical distribution, P. pekinensis is mainly distributed in the southern part of Korea, while P. tenuifoilus and P. schrenkii are commonly found all over the country.

• Korean Journal of Breeding Science
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• v.42 no.1
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• pp.40-49
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• 2010

This study was conducted to examine genetic variation on leaf characteristics of Zelkova serrata populations. Leaf samples were obtained from eighteen populations and fourteen leaf characteristics such as leaf blade length, leaf width, leaf area and etc. were measured. In all leaf characteristics, there were significant differences among populations and among individuals within population. Most variance of leaf characteristics was contributed to among individuals within population except for length from leaf base to maximum width (x3) and the ratio of x3 to leaf blade length (x10). The relatively high variations of leaf characteristics were found at Gurye, Jungeup and Gyungju populations while Youngwol, Cheongsong, Youngchun populations showed the lower variation. There was high correlation among leaf characteristics related to leaf size, but not among the variables of ratio between leaf characteristics. Length from leaf base to maximum width(x3) and the ratio of x3 to x10 showed significant positive correlation with latitude and altitude of populations, which reflect the differences of mean annual temperature among populations. Mean annual rainfall of populations showed negative correlation with leaf blade length, leaf width, length from apex to first serration and leaf area. Four principal components (PC) were deduced from principal component analysis, which explain the 88.5% of total variance of leaf characteristics. Leaf area, length from leaf base to maximum width, serration number and petiole length showed the highest contribution to PC1, PC2, PC3, PC4, respectively. According to cluster analysis, the populations of Z. serrata were divided into two groups, which reflect the difference of mean annual temperature between groups. Within group, however, specific tendency of clustering was not observed among populattions.

• The Korean Journal of Ecology
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• v.20 no.5
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• pp.339-345
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• 1997

The Arisaema robustum, perennial non-stem herb, population in the temperate forest of Sanseong-ri, Joongbu-myeon, Kyonggi Province was studied for leaf pattern and leaf growth from 1993 to 1995. The area of each side leaflet was larger than that of the apical leaflet in 3-leaflet form plants. But there was no significant difference among the leaflets (apical, 1st side and 2nd side leaflet) in t-testing of the 5-leaflet form plants. The specific leaf area (SLA) of the 3-leaflet form plant was greater than that of the 5-leaflet form plant, and the difference was significant at 0.1%. But differences of SLA value among the leafleats of the same leaflet form plants were minor. The area of leaflets or total leaf area was inversely proportioned to the their SLA values. Especially, the correlation coefficients (CC) between leaf area and SLA in apical leaflets and side leaflets of the 3-leaflet form plant compared to the 1st side leaflets of the 5-leaflet form plants were significant at the level of 1%. The differences between two sides in the dry weight and area of leaflets starting from the apical leaflets were about 5%. The CC values between attributes of the petiole (length and dry weight) and those of leaf blades (dry weight, leaf area and SLA) were high and significant at a 1% level. Especially, The CC value between the dry weight of the petioles and that of the leaf blades was higher than any others (r=0.952). The morphologies of the leaf margins were entire, medium serrate and serrate, and the same plant showed the same type from year to year. The plants usually had one leaf and occasionally 2 leaves. 1-leaf plants usually had 3 or 5 leaflets and occasionally 2 or 4 leaflets. Each year, the ration of individuals having the same number of leaflets was 72%, and that of individuals having a different number of leaflets was 27.54% (an increase of 20.4% and a decrease of 7.1% respectively). In the individuals increasing in the number of leaflets, the ration of individuals shifting from the 3-leaflet from to the 5-leaflet form was 14%. The increase ration of leaf area per individual a year was 37%, and the increase ratios of the plants increasing in leaflets were 60-70% regardiness of leaflet increase. The ratios of leaflet length/breadth were about 1-2, and the variations of those were 0.182-0.286 each year (12-20%).