• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.1
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• pp.59-66
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• 2019

The growth and maturation pattern of a commercial and endemic red algae Meristotheca papulosa were investigated in Jeju Island. Ecological researches were performed in a natural population of 10 m water depth in Sinheung from march 2014 to November 2015. Maximal blade length and weight of M. papulosa were 8.7 cm and 5.49 g in July 2014 and 10.7 cm and 10.17 g in September 2015, respectively. Growth in blade area of the species reached a maximum of $43.84cm^2$ and $67.41cm^2$ in July 2014 and 2015, respectively. Thalli in the field population were rarely observed from October to December but new recruits were found from January, following year. Carposporophytes were observed from June to September when bottom seawater temperatures were around $20^{\circ}C$. At the study site, seawater temperature was in the range of $14.9-25.7^{\circ}C$. Growth parameters of M. papulosa and relative abundance of carposporophytes showed significant correlation with environmental factors (temperature, salinity, DIN). In this result, we clarified the growth and maturation period of M. palpulosa, and provided effective data on the protection and management of natural populations and basic data for mass culture of the alga.

• Korean Journal of Agricultural Science
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• v.41 no.4
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• pp.309-314
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• 2014

A total of 67 watermelon accessions which include 37 accessions from Korean and 27 accessions from Turkish germplasm and 3 accessions of other related species from USA were investigated for morphological characteristics. The UPOV descriptor list for 56 characters (6 seedlings, 4 plants, 11 leaves, 5 flowers, 23 fruits and 7 seeds) was used in characterization. In addition, eight quantitative characters, hypocotyl length, cotyledon width, cotyledon length, fruit weight, fruit length, fruit width, thickness of outer layer of pericarp and soluble solid content were also measured. The 56 qualitatively scored characters were analyzed by principle coordinate analysis (PCoA) while the eight quantitative ones were subjected to principle component analysis (PCA). Morphological characterization result demonstrated that the accessions displayed high morphological diversity(how much percent?). A high level of phenotypic diversity was observed from the results of morphological characterization. However, plant growth habit and leaf blade flecking showed constant characters for all of the accessions. The Korean and Turkish watermelon genotypes are diverse groups and can be separated by both multivariate analysis of morphological characters although the grouping was more apparent in PCoS results.

• Asian Journal of Turfgrass Science
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• v.26 no.1
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• pp.1-7
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• 2012

Field experiments were conducted to evaluate the morphological characteristics and growth rates of 101 medium-leaf type zoysiagrasses (Zoysia spp.) collected at the major sod production area (Jang Seong Gun) in South Korea. Collected lines with distinctive morphology and visual growth rate were planted in plastic pots and measured morphological characteristics under the plastic house conditions. Variation of leaf width, plant height, leaf angle, length of leaf sheath, trichome, stolon length, and color were measured. Six lines were selected by evaluating growth rates from one hundred one collected lines. Eight standard cultivars and three other superior lines previously collected were compared to 7 selected lines form Jang seong area by checking growth rates and morphological characteristics. Average leaf blade width was 3.4 mm, leaf angle was 45.8 degree, plant height was 21.6 cm, height of lowest leaf was 5.0 cm, and length of leaf blade was 14.1 cm. Ground cover rates of selected lines 'CY6097' and 'CY6069' were 70% and 68.3%, respectively. These are believed to be faster than 60% ground cover rate of zoysiagrass 'Anyang', and also, twice as faster than the 31.7% ground cover rate of Z. matrella. Selected line 'CY6069' showed fast growth rate with shorter internode length (5.1 cm) compared to zoysiagrass 'Anyang'. Based on the results of this study, we could select useful fast growing zoysiagrass breeding lines from the major sod production area (Jang Seong Gun) in Korea.

• 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.

• Journal of The Korean Society of Grassland and Forage Science
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• v.4 no.3
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• pp.201-205
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• 1984

For the forage sorghum breeding, 22 American M.S. lines and 58 inbred lines were sown in pots, and 80 local varieties in field in 1978. Their agronomic characteristics were as follow; 1. All of the tested lines/varieties were headed from 22nd to 26th of July. Varieties of 69-86% were headed from 17th to 31st of July. All of lines/varieties began their flowering within 3-5 days after heading and native varieties had wide variance in heading and flowering. 2. The plant height of M.S. lines, inbred lines and local varieties were 86-114 cm, 81-190 cm and 142-289 cm, respectively. Leaf blade length of M.S. lines and inbred lines were ranged from 52.2 to 53.4 cm and local varieties 70.7 cm. Average stem diameter of M.S. lines and inbred lines were ranged from 8.81 to 7.74 mm and local varieties 11.3 mm. 3. Stem diameter were significantly correlated with leaf length and leaf blade width. The internode length were also significantly correlated with plant height. Especially, all characteristics in local varieties were correlated with each other.

• Journal of Biosystems Engineering
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• v.36 no.1
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• pp.9-14
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• 2011

This study was carried out to develop a vine crusher for harvesting sweet potato. The experimental two-row vine crusher attachable to agricultural tractor composed of vine crushing part with frail type vine crushing blades and vine lifting blades, power transmission part with chain and gear transmission mechanism, crushing height control part with two control wheels and manual levers, and implement frames, was designed and fabricated. And this vine crushing performance was also analyzed. From vine crushing tests, backward travel direction (i.e., rotational direction of the vine crushing blades) showed better vine crushing performance than forward travel direction. Crushing ratio of remained vine was increased, and length of remained vine and length of crushed vine were decreased as working speed was decreased and rotational speed of vine crushing blades was increased. At a working speed of 0.27 m/s and rotational speed of vine crushing blades of 800 rpm, crushing ratio of remained vine was 98%, length of remained vine was 104 mm, and length of crushed vine was 327 mm. But, when crushing vine on irregular ridges, vines and mulching vinyl were wound in the vine crushing part. Therefore, change of location of power transmission chain mechanism, and an automatic control device for controlling crushing height were needed.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.5
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• pp.44-52
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• 2012

Fuel cell electric vehicles have some noise problems due to its air processing unit which is required to feed the ambient air into the fuel cell stack. Discrete-frequency noises are radiated from a centrifugal blower due to rotor-stator interaction. Their fundamental frequency is the blade passing frequency, which is determined by the number of rotor blades and their rotating speed. To reduce such noises, multi-chamber perforated muffler has been designed. In this paper, in order to improve the transmission loss of a perforated muffler, the relationship between the impedance model of a perforated hole and its noise reduction performance is studied, and the applicability of a short-length perforated muffler to air processing unit of fuel cell system is described using acoustic simulation results and experimental data. The acoustic velocity vector across the neck of a perforated hole is very important design factor to optimize the transmission of an intake muffler. The suggested short-length perforated muffler is effective on discrete-frequency noises while keeping the volume of intake muffler minimized.

• Korean Journal of Plant Taxonomy
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• v.38 no.3
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• pp.233-250
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• 2008

Morphological and molecular data from the nuclear ribosomal ITS regions were examined to reevaluate the taxonomic position of the Korean endemic species, Stewartia koreana Nakai ex Rehder (Theaceae). Comparing to its morphologically closely related S. pseudocamellia Maxim, S. koreana has diagnostic characters including a larger leaf blade (10 cm length and 5.5 cm wide) and a longer pedicel (2.5 cm length). In addition, S. koreana formed a different clade from S. pseudocamellia in the ITS trees. The morphological and ITS sequence data supported S. koreana as a Korean endemic species distinct from the closely related species, S. pseudocamellia.

• Korean Journal of Agricultural Science
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• v.2 no.1
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• pp.125-130
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• 1975

This investigation was carried out to define the cultivation state of Ginseng seedling and to study the growth of important characters by location and correlations between characters, the results obtained are summarized as follows; 1. Most of farmers culitvating ginseng seedling had not any special consideration for the improvement of soil, and they applied green manure only as basic fertilizer but they did not apply chemical fertilizer. 2. Any efforts on the improvement of ginseng seed were not found. Seed was harvested from 3 years old ginseng plant. Seedling density was 1.8 cm by 2 cm. 3. Growth of all characters showed significant differences among farms. Coefficients of variation among individual seedling plants was largest at root diameter and smallest at root length. 4. Gromth of all characters without root diameter by planted location under the shadow was poor at front row, however root diameter was shortest at back row. 5. Significant high correlatons were rocognized between root diameter and stem diameter, between leaf blade and stem diameter and between leaf blade and leaf length, but stem length were not correlated with any characters. It is noticable that negative correlations were found between stem length and root diameter, between stem length and root length and between stem length and stem diameter.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.180.1-180.1
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• 2010

This paper introduces a 3MW embedded Permanent Magnet Synchronous Generator(PMSG) for wind turbine. The generator features 313mm stator inner radius and 974mm stator length. The blade rotor angular velocity is 15.7 rpm and the gear ratio is set to be 92.93. The nominal generator rpm at rated load is about 1459. The number of poles is six and embedded in the generator rotor. Embedded permanent magnet excitation shows higher reliability, and better efficiency. Using the finite element method, electromagnetic and thermal results are simulated by ANSYS and the results are summarized in this report.