• Journal of agriculture & life science
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• v.50 no.1
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• pp.73-81
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• 2016

The objectives of this study were to determine the effects of thinning intensity on the changes of vegetation structure in Japanese Evergreen Oak(Quercus acuta Thunb.) stands in Wando-arboretum. The flora were composed of 24 families, 33 genera, and 36species in thinned sites. The dominant layer of control site showed higher number of plant species than that of treatment sites. On the while, the sub-dominant layer, shrub layer, and herbaceous layer treatment sites showed higher number of plant species than control site. According to the analysis of importance value, Q. acuta in the dominant layer, Q. acuta and Camellia japonica in sub-dominant layer, and Camellia japonica in shrub layer showed the highest importance values, respectively. The importance value of Trachelospermum asiaticum was the highest in the herbaceous layer. According to the results, species diversity was higher in descending order of heavy thinning, light thinning, and control. This result could be explained by increased light transmissions from higher thinning intensity than in other treatments. In this context, the results of this study may be useful for selecting appropriate tending methods in terms of forest management and biodiversity conservation.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.78-78
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• 2022

Food productivity in North Korea is about 50% lower than in South Korea. In order to increase the productivity of major crops, it is necessary to develop early maturing, disease resistance, and high-yielding varieties and apply them early. Since the late 1990s, North Korea has been actively developing potatoes, rice and com as major food crops, and soybeans are considered important as a protein-supplying crop. Domestic cultivated varieties, which are expected to be most adaptable eco-climatologically, are mainly selected from soil with high nutrient soil. It is necessary to test separately for adaptability in low organic soil. So it is very necessary to apply technology to improve soil improvement through rotational crop selection in the middle and long-term. Therefore, this study was conducted to test the adaptability to low organic soils of domestic cultivars and to select varieties. In 2021 there are twenty two (22) varieties of soybeans were grown in low organic soil at the field of Chungbuk National University. This year twenty two (22) varieties of soybeans were also grown in low organic soil at the field of Chungbuk National University. Sowing was done on June 10, the planting distance was 70cm × 15cm, after opening the cotyledons fully, the soybeans were thinned and leaving two plants per hole. In addition, various types of growth characteristics and quantitative components were investigated to evaluate the adaptability to low organic soil of domestic varieties. This study was conducted to investigate the growth characteristics and quantitative components of soybean varieties grown in low organic soil. The flowering period of 22 varieties of soybeans was about 14 days from July 22 to August 4. The flowers of the beans were white, purple, light purple and the pubescence color was gray and brown where most of them were gray. The highest plant height was up to 130.4 cm and lowest was 20.3 cm, highest stem length was up to 119.5 cm and lowest was 15.3 cm. Highest first pod height (FPH) was up to 34.0 cm and lowest was 3.0 cm. Highest stem diameter was up to 15.76mm and lowest was 1.76 mm. Number of main stem nodes was up to 19 and at least 1. Number of branch was up to 10 and at least 0. The number of pod per plant was up to 121. Bacterial pustule has been spread in soybean field.

• Korean Journal of Plant Resources
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• v.37 no.1
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• pp.62-70
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• 2024

Fruit thinning rate and characteristics were investigated for three years on seven promising pear (Pyrus pyrifolia Nakai) cultivars, which were treated by lime-sulfur as an eco-chemical thinning substance. Lime-sulfur was treated twice at the second and third days after full bloom by cultivar. Most of pear cultivars were significantly thinned by lime-sulfur compounds. Especially 'Whangkeumbae', 'Supergold' and 'Hanareum' exhibited high flower thinning rates, 41.5%, 40.1% and 39.9%, respectively. As weather conditions at the lime-sulfur treatment, insolation and cloud amount were correlated with flower thinning rate but not significant (r = 0.49 and r = -0.45, respectively). These results suggest that lime-sulfur is suitable for reducing labor force for flower thinning of Korean pears but flower thinning effects of lime-sulfur can vary depending on other factors such as environmental conditions. This information will provide useful data for low labor force cultivation of Korean pear cultivars.

• The korean journal of orthodontics
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• v.32 no.6 s.95
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• pp.455-466
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• 2002

The objective of this study was to evaluate the changes that occurred over time in the distracted periodontal ligament space following the rapid retraction of a tooth by periodontal distraction after bone undermining surgery had been conducted in the dogs. The upper second premolars were extracted on the left and right side in 4 male beagle dogs. Immediately after extraction, the interseptal bone distal to the upper first premolar was thinned and undermined by grooving to decrease the bone resistance. Activating an individualized distraction appliance at the rate of 0.225mm twice a day, the upper first premolar was retracted rapidly toward the extraction socket. Periodontal distractions were performed for 5, 10, and 20 days, and 20-day-distraction cases were followed by maintenance periods of 0, 14, 28, and 56 days. After 20 days of rapid retraction, the average distal movement of the upper first premolar was 5.02mm, and the average mesial movement of the upper third premolars serving as an anchorage unit was 0.18 mm. On histological examination, the regeneration of bone occurred in a highly organized pattern. Distracted periodontal ligament space was filled with newly formed bone oriented in the direction of the distraction, and this was followed by extensive bone remodeling. This result was similar to those observed in other bones after distraction osteogenesis. In the periodontal ligament, the relationship between collagen fibers and cementum began to be restored 2 weeks after the distraction was completed, and showed almost normal features 8weeks after the completion of the periodontal distraction. However, on the alveolar side, the new bone formation was still in process and collagen fiber bundles and Sharpey's fibers were not present 8 weeks after the completion of the periodontal distraction. Reactions in the periodontal ligament of the anchorage tooth represented bone resorption on the compressed side and new bone deposition on the tension side as occurred in conventional orthodontic tooth movement. In conclusion, the results of this study showed that periodontal structures on the distracted side of the periodontal ligament were regenerated well histologically following rapid tooth movement.

• Journal of Forest and Environmental Science
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• v.24 no.1
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• pp.41-46
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• 2008

Progeny tests of Abies holophylla were established with 32 open-pollinated families at Hwaseong and Gangneung in 1994. Growth characteristics (height, DBH and volume index) were measured at the age of 15, showing that Gangneung site showed in general better performance than Hwaseong site. Analysis of variance (ANOVA) of the growth characteristics showed that there was a significant difference among families in Gangneung but not in Hwaseong, and Hwaseong site showed that DBH and volume index were statistically different among replications. At Gangneung site, family ${\times}$ replication interaction was significant in DBH and volume index. Based on the combined analysis of both sites, all characteristics except height showed highly significant differences between sites and among families. On the other hand, family ${\times}$ replication interaction was not significant, implying that growth pattern of families could be similar at Gangneung and Hwaseong. Individual heritabilities ($hi^2$) at Gangneung were 0.485 in height, 0.611 in DBH and 0.538 in volume index, and the values of $hi^2$ at Hwaseong were 0.121 in height, 0.054 in DBH and 0.080 in volume index, respectively. Based on both sites, $hi^2$ was estimated as 0.204 in height, 0.326 in DBH and 0.238 in volume index. Individual heritabilities (0.054~0.611) were lower than family heritabilities (0.089~0.723) for all growth characteristics. Realized gain was estimated to be 2.5% in height, 9.2% in DBH and 23.6% in volume. When inferior families (about 50% of all families) are genetically thinned from a seed orchard, genetic gain would be 9.55% in height, 17.0% in DBH and 46.8% in volume.

• Journal of The Korean Society of Grassland and Forage Science
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• v.12 no.1
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• pp.49-58
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• 1992

The purpose of the experiment was to determine the effect of plant density and pattern on growth characteristics, total dry matter yield. protein yield and palatability of sorghum-sudangrass hybrid (Sordan 79). The main treatment was three levels of plant density (Skg, 15kg. 30kg/ha) and the sub treatment was two plant patterns of square and rectangular planting.The experiment was arranged as a split plot design and conducted on the Experimental Livestock Farm of Kon-Kuk Univ. in Chungju, 1989. The results obtained are summarized as follows :1. As the plant density was increased, plant length, leaf length, leaf width(P<0.05) and leaf number were gradually decreased, but in the same plant density, plant length, leaf length, leaf width and leaf number were generally increased in the rectangular plot. 2. In the first cutting time, the ratio of leaf was the highest at the rectangular plot of high density (30kg/ha, 25cm$\times$4cm), but in the second cutting time, the ratio of leaf was the highest at the square plot of medium density (15kg/ha, 14cm$\times$ 14cm). 3. The ratio of dead stubble after cutting was generally increased by increasing the plant density. Also, in the same planting density, the ratio of dead stubble was generally increased in the square plot. 4. The tiller number per plant tended to decreased by increasing thc plant density, and the tiller number was increased in the rectangular plot. In the same plant density. 5. Total fresh and dry matter yield were the highest at the rectangular plot of medium density (IS kg/ha, 33cm$\times$6cm) wholly, but the low density was shown the lowest.6. The crude protein content was increased by increasing the plant density per unit area(P<0.05) and the protein yield was also increased by increasing the planting density. 7. According to the increase of plant density, the stem was thinned, but NDF, ADF did not show different. The palatability was in the order of high (30kg/ha))medium (15kg/ha))low density(5kgiha) at the first cutting time, but it was in the order of high)low)medium density at the second cutting time.

• Journal of The Korean Society of Grassland and Forage Science
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• v.12 no.1
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• pp.19.2-19.2
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• 1992

The purpose of the experiment was to determine the effect of plant density and pattern on growthcharacteristics, total dry matter yield. protein yield and palatability of sorghum-sudangrass hybrid(Sordan 79). The main treatment was three levels of plant density (Skg, 15kg. 30kg/ha) and the subtreatment was two plant patterns of square and rectangular planting.The experiment was arranged as a split plot design and conducted on the Experimental Livestock Farm of Kon-Kuk Univ. in Chungju, 1989.The results obtained are summarized as follows :1. As the plant density was increased, plant length, leaf length, leaf width(P<0.05) and leaf number were gradually decreased, but in the same plant density, plant length, leaf length, leaf width and leaf number were generally increased in the rectangular plot.2. In the first cutting time, the ratio of leaf was the highest at the rectangular plot of high density(30kg/ha, 25cm$\times$4cm), but in the second cutting time, the ratio of leaf was the highest at the square plot of medium density (15kg/ha, 14cm$\times$ 14cm). 3. The ratio of dead stubble after cutting was generally increased by increasing the plant density. Also, in the same planting density, the ratio of dead stubble was generally increased in the square plot. 4. The tiller number per plant tended to decreased by increasing thc plant density, and the tiller number was increased in the rectangular plot. In the same plant density. 5. Total fresh and dry matter yield were the highest at the rectangular plot of medium density (ISkg/ha, 33cm$\times$6cm) wholly, but the low density was shown the lowest.6. The crude protein content was increased by increasing the plant density per unit area(P<0.05) and the protein yield was also increased by increasing the planting density. 7. According to the increase of plant density, the stem was thinned, but NDF, ADF did not show different. The palatability was in the order of high (30kg/ha))medium (15kg/ha))low density(5kgiha)at the first cutting time, but it was in the order of high)low)medium density at the second cutting time.

• Journal of Korean Society of Forest Science
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• v.97 no.6
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• pp.605-610
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• 2008

This study was carried out to investigate the short-term (3 years) effect of thinning on aboveground carbon storage for 34-year-old (site 1) and 45-year-old (site 2) Korean pine (Pinus koraiensis Siebold et Zuccarini) plantations with different diameter class and site quality located in Gwangneung experimental forest. Thinning was manually carried out in consideration of basal area in 2004 (site 1 : 30% and 60% of basal area removed and site 2 : 60% of basal area removed). In 2004 and 2007, DBH and tree height were measured to analyze the changes in carbon storage after thinning. In the sites of 60% of basal area removed, although the mean DBH of site 1 was higher than that of site 2, mean annual carbon storage increment in site 2 ($6.5Mg\;C\;ha^{-1}yr^{-1}$) was about 3 times higher than that in site 1 ($2.3Mg\;C\;ha^{-1}yr^{-1}$). The reason for this result was probably due to higher stem density and site quality in site 2 compared to site 1. In site 2, mean annual carbon storage increment in thinned plot ($6.5Mg\;C\;ha^{-1}yr^{-1}$) was about 1.3 times higher than that in control ($5.2Mg\;C\;ha^{-1}yr^{-1}$). The results suggest that the stem density and site quality may be much more related to the aboveground carbon storage compared to diameter class. In addition, it is needed to consider these two factors for determining whether thinning is a feasible management alternative for the increase in aboveground carbon sequestration.

• Journal of the Korean Geophysical Society
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• v.2 no.1
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• pp.9-26
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• 1999

The Ulleung Basin (Tsushima Basin) in the southwestern East Sea (Japan Sea) is floored by a crust whose affinity is not known whether oceanic or thinned continental. This ambiguity resulted in unconstrained mechanisms of basin evolution. The present work attempts to define the nature of the crust of the Ulleung Basin and its tectonic evolution using seismic wide-angle reflection and refraction data recorded on ocean bottom seismometers (OBSs). Although the thickness of (10 km) of the crust is greater than typical oceanic crust, tau-p analysis of OBS data and forward modeling by 2-D ray tracing suggest that it is oceanic in character: (1) the crust consists of laterally consistent upper and lower layers that are typical of oceanic layers 2 and 3 in seismic velocity and gradient distribution and (2) layer 2C, the transition between layer 2 and layer 3 in oceanic crust, is manifested by a continuous velocity increase from 5.7 to 6.3 km/s over the thickness interval of about 1 km between the upper and lower layers. Therefore it is not likely that the Ulleung Basin was formed by the crustal extension of the southwestern Japan Arc where crustal structure is typically continental. Instead, the thickness of the crust and its velocity structure suggest that the Ulleung Basin was formed by seafloor spreading in a region of hotter than normal mantle surrounding a distant mantle plume, not directly above the core of the plume. It seems that the mantle plume was located in northeast China. This suggestion is consistent with geochemical data that indicate the influence of a mantle plume on the production of volcanic rocks in and around the Ulleung Basin. Thus we propose that the opening models of the southwestern East Sea should incorporate seafloor spreading and the influence of a mantle plume rather than the extension of the crust of the Japan Arc.

• Journal of Korean Society of Forest Science
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• v.103 no.1
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• pp.30-36
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• 2014

This study examined the change in carbon (C) storage of soil, forest floor and coarse woody debris (CWD) for different thinning intensities in Pinus densiflora stands 4 years after the treatment. Two study stands were located in Jeongseon (Stand 1) and Gwangneung Experiment Forest (Stand 2). Three plots for different thinning intensities based on stand density were established at each stand in 2008; control plot (0%), T20 plot (20%) and T30 plot (30%) in Stand 1 and control plot (0%), T39 plot (39%) and T74 plot (74%) in Stand 2, respectively. The C storage of soil (0-50 cm), forest floor and CWD was measured in 2012. Total C storage of T30 plot ($109.80t{\cdot}C{\cdot}ha^{-1}$) was significantly higher than that of control plot ($86.69t{\cdot}C{\cdot}ha^{-1}$) in Stand 1. In stand 2, total C storage of T74 plot ($97.02t{\cdot}C{\cdot}ha^{-1}$) was significantly higher than that of control plot ($72.04t{\cdot}C{\cdot}ha^{-1}$) and T39 plot ($63.25t{\cdot}C{\cdot}ha^{-1}$). Total C storage of the heaviest thinned plot was the highest in each study stand. Since this study examined initial effects of thinning on C storage of soil, forest floor and CWD, further studies would be necessary to evaluate the long-term effects.