• 대한수학회논문집
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• 제16권1호
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• pp.67-73
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• 2001

We classify self-converse oriented trees into two types, namely, bicentral self-converse oriented trees and central ones, according to their centers and characterize these tow types. Using characterizations and Polya enumeration theorem, we derive the ordinary generating function for self-converse oriented trees.

• 대한수학회논문집
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• 제18권1호
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• pp.181-192
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• 2003

We count the numbers of independent dominating sets of rooted labeled trees, ordinary labeled trees, and recursive trees, respectively.

• 임산에너지
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• 제1권2호
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• pp.1-19
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• 1981

In order to investigate biomass yield of one-year-old hyblrid poplars, Pripulusalba x P. glandulosa $F_1$ and Populus nigra var. italica x P. maximowiczii $F_1$clones, as energy and fiber resources, dry matter yield, leaf area, leaf area index, dry matter production ability, specific gravity and fiber length and width were measured. Dry matter yield was 1.89 ton/ha for Poplus alba x P. glandulosa $F_1$ and 3.63 ton/ha for Populus nigra via.italica x P. merximowiczii $F_1$ clones in the planting density of 20,000 trees/ha and in the planting density of 40,000 trees/ha was 3.87 ton/ha for Populus alba x P. glandulosa $F_1$and 5.64 ton/ha for Populus nigra var. italica x P. maximowiczii $F_1$ clones. Leaf area index was 1.24mtim2 in the planting density of 20,000 trees/ha and 2.45 m31m3 in the density of 40,000 trees/ha for Populus alba x P. glandulosa $F_1$ clones and it was 1.96 m21m2 in the planting density of 20,000 trees/ha and 3.36 m21m2 in the density of 40,000 trees/ha for the hybrid $F_1$ Populus nigra var. italica x P. maximowiczii clones. The average specific gravity of the hybrid poplars was 0..36 when bark and pith were included and 0.31 when bark and pith were removed in the plot of 20,000 trees/ha and in the 40,000 trees/ha plot showed 0.35 and 0.31 respectively, for Populus alba x P. glandulosa $F_1$clones. It was 0.36 when bark and pith were included and 0.32 when bark and pith were removed in the 20,000 trees/ha plot and in the 40,000 trees/ha plot was 0.34 and 0.31 respectively for Populus nigra var. italica x P. maximowiczii $F_1$clones. The average fiber length was 0.57 mm in the 20,000 trees/ha plot and 0.58 mm in the 40,000 trees/ha plot for Poplus alba x P. glandulosa $F_1$clones and was 0.60 in both plots of 20,000 trees/ha and 40,000 trees/ha for Populus nigra var. italica x P. maximowiczii $F_1$ clones. There is a big clonal variation among those clones studied, showing high selection potential in both species.

• 자연과학논문집
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• 제16권1호
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• pp.77-86
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• 2005

The study was designed to learn about features of landscape trees and shrubs on an exclusive area-specific outer space planting plan in Noeun Apartment Complex in Daejeon Metropolitan City. the exclusive areas were no more than $60m^2$ and $85m^2$ and the landscape areas ranged from 15% and 30%, respectively according to exclusive area-to-plottage ratios. The study showed that trees were likely to be more densely planted in exclusive areas not exceeding $60m^2$ than in exclusive areas over $85m^2$. It also found that the greater the exclusive areas were, the larger the number of species became. Regardless of the size of an exclusive use, however, the species number of evergreen trees and shrubs remained small, while there was no remarkable difference in vegetation due largely to a massive influx of special trees or shrubs such as Eastern white pines (Pinus strobus) and Korean azaleas (Rhododendron yedoensis var. poukhanense). The introduction of trees with the height over four meters and the diameter of breast height (DBH) exceeding 15 meters was strictly limited to Japanese red pins (Pinus densiflora) and Japanese zelkovas (Zelkova serrata). In conclusion, it is necessary for us to introduce fresh species of trees and especially develop evergreen trees and shrubs to make the environment of the apartment complex more comfortable and make a vegetation experience feasible.

• Wind and Structures
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• 제22권1호
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• pp.89-106
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• 2016

With an aim to assess the wind damage to urban trees in more realistic conditions, the nonlinear dynamics of structured trees subjected to strong winds with different levels is investigated in the present paper. For the logical treatment of dynamical behavior of trees, material nonlinearities of green wood associated with tree biomechanics and geometric nonlinearity of tree configuration are included. Applying simulated fluctuating wind velocity to the numerical model, the dynamical behavior of the structured tree is explored. A comparative study against the linear dynamics analysis usually involved in the previous researches is carried out. The failure wind velocity of urban trees is then defined, whereby the failure percentages of the tree components are exposed. Numerical investigations reveal that the nonlinear dynamics analysis of urban trees results in a more accurate solution of wind-induced response than the classical linear dynamics analysis, where the nonlinear effect of the tree behavior gives rise to be strengthened as increasing of the levels of wind velocity, i.e., the amplitude of 10-min mean wind velocity. The study of relationship between the failure percentage and the failure wind velocity provides a new perspective towards the vulnerability assessment of urban trees likely to fail due to wind actions, which is potential to link with the practical engineering.

• Spatial Information Research
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• 제20권6호
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• pp.45-57
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• 2012

도시지역의 가로수는 보행자와 운전자에게 쾌적한 환경을 제공하며 탄소를 흡수하는 중요한 역할을 수행한다. 따라서 가로수의 위치, 수고, 수관폭 등에 대한 효율적인 획득과 관리가 필요하다. 본 연구는 항공라이다 자료를 이용하여 도시지역 가로수에 대한 개수, 위치, 수고, 수관폭의 수치적인 정보를 추출하는 방법론을 제안하였다. 가로수는 그 형태와 크기가 다를 수 있기 때문에 본 연구에서는 수관폭의 크기를 변화시키면서 가로수를 추출하는 방법을 제안하였다. 또한 가로수는 일반적으로 도로변을 중심으로 식재되기 때문에 이러한 식재위치의 직선적 특성을 이용하여 가로수점들을 선택하였다. 오산시 일부를 대상으로 가로수 추출에 대한 실험을 수행하였으며 결과는 1/1,000 수치지도와 비교하여 제안한 방법론의 적합성을 평가하였다. 실험 결과를 통해서, 가로수의 위치오차는 최소 0.5m, 최대 1.9m, 그리고 평균제곱근오차는 약 ${\pm}0.4m$를 나타냈다.

• 대한토목학회논문집
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• 제31권4B호
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• pp.323-332
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• 2011

하천에서 수목의 관리를 위해서는 수목이 홍수에 미치는 영향이나 생태적 특성을 고려하여 대책을 수립하여야 한다. 수목에 의한 수리학적 영향은 통수능 감소와 유수력에 의한 전도로 인한 하류 하천시설물의 기능 저해이다. 현장 인발시험은 수목이 전도될 때의 최대 저항력을 측정하여, 하천 내의 수목이 외력에 저항하는 정도를 파악하기 위해 시행하였다. 수목의 전도모멘트를 파악하기 위한 인자는 수목의 외형적 특성인 수종, 흉고직경, 수고 등이며, 본 연구에서는 전도모멘트와 흉고 직경의 상관관계를 이용하였다. 수목의 한계 전도모멘트는 흉고직경 4.9-32.8 cm의 관목과 교목 100주를 바탕으로 검토되었다. 교목과 관목을 함께 고려할 경우에는 흉고직경과 한계 전도모멘트의 상관관계를 도출하기 어려웠다. 그러나 교목만을 고려할 경우에는 흉고직경과 한계 전도모멘트 사이에 일정한 상관관계가 있음을 확인하였다.

• 한국환경농학회지
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• 제35권4호
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• pp.256-262
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• 2016

BACKGROUND: 'Shiranuhi' mandarin is one of the popular citrus cultivars in Jeju Island, Korea. However, the emergence of scion roots since the past few years has altered its flowering, fruiting, and quality. Girdling of branches is one of the methods of increasing flowering in citrus trees. METHODS AND RESULTS: This experiment was conducted to determine the effect of girdling on the flowering and yields of scion rooted 'Shiranuhi' mandarin hybrid. We selected normal trees without scion roots as controls. The trees with scion roots were divided into two groups: trees without girdling and with girdling on main branches. Each group contained five replications and the experiment was conducted in Gosan and Harye of Jeju Island. The scion rooted trees revealed severely decreased flowering and low flowering/leaf ratios; however, the leaf/fruit ratio significantly increased. But, girdling on main branches significantly increased flowering and the flowering/leaf ratio. In the scion rooted trees, yields dropped due to poor flowering; however, girdling of branches efficiently improved the yields of the trees. Fruit quality, fruit size, and fruit weight of scion rooted trees were low in comparison with the control, whereas girdling of the branches improved flowering and the fruit weight to some extent. No significant difference in soluble solid contents was observed. CONCLUSION: Girdling is an effective method to induce flowering of the scion rooted 'Shiranuhi' mandarin trees. In addition, yields of scion rooted trees were improved.

• 한국산림과학회지
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• 제96권2호
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• pp.170-177
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• 2007

The objectives of this study were to select early, late, and abundant flowering trees of black locust from domesticated and introduced cultivars, and prediction of flowering period by calculation of accumulated temperature in spring. Four cultivars (Debreceni-2, Pusztavacs, Jaszkiseri, and Rozsaszin AC) from Hungary and a cultivar from Beijing, China, were introduced, propagated by seed and planted in a seed orchard. For domesticated black locust, 63 cultivars from 10 locations throughout the country were selected and propagated by root cutting. Criteria for selection of domesticated cultivars were abundant flowering, long flowering period, or abundant nectar production with, if possible, straight stems. Accumulated temperature was calculated from data of a nearby weather station by accumulating daily maximum temperature minus 5 degree Celsius from January 1 up to the date reaching 880 degrees. Daily mean temperature was also used to calculate accumulated temperature up to the date reaching 450 degrees. The percentages of two-year and three-year-old flowering trees propagated by root cutting were higher than that of trees propagated by seeds, while four-year-old trees all flowered regardless of propagation methods. Among the domesticated cultivars, all the cultivars from Ganghwa showed abundant flowering with highest nectar production of 6.5 ul per flower, which was 100% more than other domesticated cultivars and 50% more than Debreceni-2 cultivar with highest nectar production among the introduced cultivars from Hungary. At the end of the eight years of observations, two trees of Debreceni-2 cultivars and a tree from Beijing, China were selected for early flowering trees which flowered 2 to 3 days earlier than average trees, while a tree of Debeceni-2 and three trees from Bejing were selected for late flowering trees which flowered 2 to 3 days later than average trees. It is possible to extend the flowering period of black locust by 4 to 6 days by planting early and late flowering cultivars together. Abundant flowering trees were unable to be selected due to severe damages by leaf gall midges which killed many trees and reduced the crown size of the remaining trees in the seed orchard, and which were first found in Korea in 2001 and now damaging most of the black locust forests in Korea. The prediction of flowering period by accumulated temperature indicated that black locust flowered to a peak when accumulated daily maximum temperature reached 880 degrees Celsius, and when daily mean temperature reached 450 degrees.

• 한국환경농학회지
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• 제38권3호
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• pp.154-158
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• 2019

BACKGROUND: 'Shiranuhi' mandarin is a major cultivar among all late ripening type of citrus, and is widely cultivated in Korea. However, many farmers have reported scion root problems in their orchard resulting in reduced flowering and fruiting. It is necessary that the physiology of scion-rooted 'Shiranuhi' mandarin trees is further understood. METHODS AND RESULTS: This experiment was conducted to understand the growth response and physiology of scion-rooted 'Shiranuhi' mandarin hybrids. In our study, 'Shiranuhi' mandarin trees were divided into two groups: trees without scion roots (control) and trees with scion roots. The experiment was conducted in Seogwipo of Jeju, with ten replicates for each group. Growth of trees with scion roots was more vigorous and the trees were taller than the controls. Tree height and trunk diameter of scion-rooted trees were significantly higher than those of control trees. Exposed length of rootstocks of scion-rooted trees was significantly lower (by about 2 cm) than that of control trees (8.6 cm). In terms of root nutrition, carbon contents of scion-rooted trees was significantly lower than that of control trees, but nitrogen and potassium concentrations in scion roots were significantly higher than those in control roots. CONCLUSION: Based on the results, we infer that growth of scion-rooted trees was very vigorous and the content of nitrogen in these roots was higher than that in the control tree roots. Thus, the carbon/nitrogen ratio of scion roots was significantly lower than that of the control roots.