• Korean Journal of Environment and Ecology
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• v.25 no.5
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• pp.736-746
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• 2011

This study aims tried to present develop a management plan for about old and big trees and legally protected trees by investigating through the present the current status and the distribution of the legally protected trees and old and big tree that range in Gwangju, South Korea. The number of legally protected plants that distributed in Gwangju City is 68 individual trees from 9 species. The largest number was found in Gwangsan-gu (18 trees). The total number of the old and big trees that are distributed in Gwangju City was confirmed as 155 individual trees from 10 species. It must to be corrected to a correct plant species name that species name is written in review articles incorrectly. The average vitality rate of the legally protected plants was 1.2 and the status of ground was 1.7 on average. And the vitality rate of the old and big trees was 1.3 and the status of ground was 2.0 on average. Vitality are not significantly different between the legally protected trees and old and big trees. Ground status of old and big trees worse than legally protected trees. Gingko biloba (found in Gwangsan-gu Songdaedong Daechon village) was only legally protected plant that requires urgent management due to low vitality rate (between 3.2 and 4.0). Among old and big trees Salix glandulosa which is found in Gwangsan-gu Sansu-dong Gamdong village was only one that requires urgent care. The most important status for the old and big tree is securing minimal space for growth. Therefore, we conclude that the most urgent measure in the management and projection of old and big trees and legally protected plants is removal of asphalt or cement above the surface of root system.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1132-1139
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• 2006

Railway risk is evaluated by a method of linking event trees and fault trees as the general PSA(Probabilistic Safety Assessment) model for the risk assessment of complex systems. Accident scenarios causing undesirable events are modeled by event trees comprised of several accident sequences. Each branch located in the accident progression of the event tree is modeled by an fault tree or can be represented by some value too simply. We usually evaluate the frequency of the whole sequence by adding them after calculating the frequency of each sequence at a time. However, since there are quite a number of event trees and fault trees in the railway risk assessment model, the number of sequence to evaluate increases and preparation for the risk assessment costs much time all the more. Also, it may induce errors when analysts perform the work of quantification. Therefore, the systematic maintenance and control of event trees and fault trees will be essential for the railway risk assessment. In this paper we introduce an integrated assessment method using one-top model and develop a risk assessment tool for the maintenance and control of the railway risk model.

• Research in Plant Disease
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• v.26 no.2
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• pp.88-94
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• 2020

Recently, the severe dieback of apple trees resulting from soil-borne diseases has occurred in South Korea. The casual agents of dieback were surveyed on 74 apple orchards that had been damaged nationwide in 2016-2019. The number of apple orchards affected alone by Phytophthora rot, violet root rot, and white root rot was 31, 34, and 3, respectively. Also, the total number of mixed infection orchards was 6. Out of 9,112 apple trees affected by dieback, the trees damaged by Phytophthora rot, violet root rot, and white root rot were 3,332, 3,831, and 44, respectively. Moreover, the total number of mixed infection apple trees was 1,905. The provinces mainly affected were Gyeongnam, Gyeongbuk, Chungbuk, and Jeonbuk. The survey on these infected apple orchards will be available to form management strategy for the dieback that had been increased by soil-borne fungal pathogens.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.23 no.6
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• pp.109-123
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• 2020

The purpose of this study is to provide basic data for the establishment of future countermeasures by diagnosing the growth status and actual condition of undesignated old trees distributed in Hyeongok-myeon, Gyeongju, Gyeongsangbuk-do. The number of old trees surveyed was 2 weeks in Gajeong-ri, 2 weeks in Haguri, 3 weeks in Nae-Tae-ri, 1 week in Nawon-ri, 6 weeks in Oryu-ri, 3 weeks in Sangguri, and 2 weeks in Sohyeon-ri, The trees species composition was 6 trees Celtis sinensis Pers., 1 Diospyros lotus L. trees, 4 trees Salix chaenomeloides Kimura trees, 2 Styphnolobium japonicum L. trees, and 7 Zelkova serrata (Thunb.) Makino trees. Growth status is 7.1~22.0m in height, 14.6~25.1m in long axis, 10.2~19.2m in short axis, root diameter is 76.0~236.4cm, diamter at breast height is 67.0~220.0cm, soil acidity is pH4.9~7.0, soil The hardness was measured to be 4.0-27.0mm. The result grade of the scoring data of health information is represented by monitoring generally, monitoring critically, and absolute monitoring, and it was confirmed that out of the 20 trees population in Hyeongok-myeon, the general monitoring grade was 7 weeks, the major monitoring grade was 13 weeks, and there was no absolute monitoring grade. Accordingly, the number of old trees of the general surveillance level was maintained at the current level, and ecological surgical operations were introduced for the major surveillance level, but the case of village forests should be different, and sequential treatments were the old tree urgently needed. The level and bark of the target tree, the state of the crown, the root exposure, the presence of pests and pests, the vitality and the ground condition, the degree of pollution are normal, poor, or very poor, operation and protection management, soil improvement, removal of cover, and disinfection were urgently needed for the old trees with the surveyed data. In order to compensate for these matters, continuous monitoring and management measures for the old number should be sought.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.23 no.5
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• pp.59-71
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• 2020

Using high-resolution stereoscopic aerial images (in 2008, 2012 and 2016), we conducted to analyze the spatial characteristics affecting evergreen coniferous die-off in the northwestern ridge (major distribution area such as Abies nephrolepis), Seoraksan National Park. The detected number of dead trees at evergreen coniferous forest (5.24㎢) was 1,223 in 2008, was 2,585 in 2012 and was 3,239 in 2016. The number of cumulated dead trees was 7,047 in 2016. In recent years, the number of dead trees increased relatively in the northwest ridge, Seoraksan National Park. Among the analysed spatial factor (altitude, aspect, slope, solar radiation and topographic wetness index), the number of dead trees was increased in the conditions with high altitude, steep slope and dry soil moisture. A spatial distribution of dead tree was divided into 2 groups largely (high altitude with high solar radiation, low altitude with steep slope). In conclusion, the dead trees of evergreen coniferous were concentrated at spatial distribution characteristics causing dryness in the northwestern ridge, Seoraksan National Park.

• Bulletin of the Korean Mathematical Society
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• v.56 no.1
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• pp.31-44
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• 2019

A graph theoretical model called Roman domination in graphs originates from the historical background that any undefended place (with no legions) of the Roman Empire must be protected by a stronger neighbor place (having two legions). It is applicable to military and commercial decision-making problems. A Roman dominating function for a graph G = (V, E) is a function $f:V{\rightarrow}\{0,1,2\}$ such that every vertex v with f(v)=0 has at least a neighbor w in G for which f(w)=2. The Roman domination number of a graph is the minimum weight ${\sum}_{v{\in}V}\;f(v)$ of a Roman dominating function. In order to deal a problem of a Roman domination-type defensive strategy under multiple simultaneous attacks, ${\acute{A}}lvarez$-Ruiz et al. [1] initiated the study of a new parameter related to Roman dominating function, which is called strong Roman domination. ${\acute{A}}lvarez$-Ruiz et al. posed the following problem: Characterize the graphs G with equal strong Roman domination number and Roman domination number. In this paper, we construct a family of trees. We prove that for a tree, its strong Roman dominance number and Roman dominance number are equal if and only if the tree belongs to this family of trees.

• Communications of the Korean Mathematical Society
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• v.33 no.2
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• pp.631-638
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• 2018

Chellai et al. [3] gave an upper bound on the [1, 2]-domination number of tree and posed an open question "how to classify trees satisfying the sharp bound?". Yang and Wu [5] gave a partial solution for tree of order n with ${\ell}$-leaves such that every non-leaf vertex has degree at least 4. In this paper, we give a new upper bound on the [1, 2]-domination number of tree which extends the result of Yang and Wu. In addition, we design a polynomial time algorithm for solving the open question. By using this algorithm, we give a characterization on the [1, 2]-domination number for trees of order n with ${\ell}$ leaves satisfying $n-{\ell}$. Thereby, the open question posed by Chellai et al. is solved.

• Journal of the Korea Computer Industry Society
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• v.2 no.2
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• pp.203-210
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• 2001

To estimate relational models and test the theoretical hypotheses of binary tree search algorithms, we built binary search trees with random permutations of n (number of nodes) distinct numbers, which ranged from three to seven. Probabilities for building binary search trees corresponding to each possible height and balance factor were estimated. Regression models with variables of number of nodes, height, and average number of comparisons were estimated and the theorem of O(1g(n)) was accepted experimentally by a Lack of Test procedure. Analysis of Variance model was applied to compare the average number of comparisons with three groups by height and balance factor of the trees to test theoretical hypotheses of a binary search tree performance statistically.

• Journal of Forest and Environmental Science
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• v.34 no.2
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• pp.162-164
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• 2018

This study quantified the carbon storage and uptake by street trees in Seoul and explored suitable planting and management strategies. A systematic sampling model was used to select 50 plots to survey the structures of street trees. The average density and cover of street trees were approximately 5.8 trees/$100m^2$ and 12.1%, respectively. Trees with a dbh of less than 30 cm accounted for about 66.3% of the total number of trees surveyed. The total carbon storage and uptake by the street trees were approximately 103,641 t and 10,992 t/yr, respectively. The total carbon uptake equaled the amount of annual carbon emissions from driving of about 11,000 cars. Street tree planting and management strategies were proposed to enhance carbon uptake. They included multi-layered and multi-aged planting, securing ground and space for plant growth, and avoiding excessive tree pruning.

• Journal of Environmental Science International
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• v.19 no.9
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• pp.1129-1136
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• 2010

This study investigated the status of planting status of school's flower of 11 elementary schools located in Chung-ju and its results were as follows. Totally 3,502 trees were planted in the 11 schools and the number of species of the trees was 103. For tall tree Thuja orientalis was planted most frequently and for shrub Buxus microphylla was done in the largest number of the schools. In addition, the number of trees planted in a school was averagely two times more in the model schools than in the other ones, and the average number of species of trees was also over three times more in the model schools. When the number of species of trees was examined according to their types, decidous broad leaved tree was found most frequently overall and the model schools had more various species of decidous tree compared to the other ones. Investigation on designation of school's flower and tree with the 11 elementary school, revealed similar results with those of previous studies performed with the schools in other areas and the tendency meant that the designation was uniform to some degree. Moreover, as only a few school's flower and tree were planted or no one was done in some schools, the species of school's flower and tree needed to be determined by considering characteristics and school percepts of a school as well as local features and circumstances of a region. In addition, more efforts should be made to infuse love for school and to improve quality of education by increasing the planting rate of school's flower and tree and by focusing them.