• IE interfaces
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• v.20 no.1
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• pp.41-48
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• 2007

The main purpose of this paper is cost reduction in absurd pilot positive expense and human accident prevention which is caused by in the pilot selection process. We use classification models such as logistic regression, decision tree, and neural network based on aptitude test results of 505 ROK Air Force applicants in 2001~2004. First, we determine the reliability and propriety against the aptitude test system which has been improved. Based on this conference flight simulator test item was compared to the new aptitude test item in order to make additional yes or no decision from different models in terms of classification accuracy, ROC and Response Threshold side. Decision tree was selected as the most efficient for each sequential flight training result and the last flight training results predict excellent. Therefore, we propose that the standard of pilot selection be adopted by the decision tree and it presents in the aptitude test item which is new a conference flight simulator test.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.516-522
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• 2020

Water trees can cause considerable damage to the performance of underground cables. Theymay formwithin the dielectric used in buried or water-immersed high voltage cables. They grow in a bush-like or tree-like form, often taking decades before causing damage to a cable's performance. They are usually found on very old underground cables, often in an inaccessible place. It is costly and time-consuming to detect watertrees in underground cables. Tree detection technology, including mathematical modeling,can reduce the maintenance cost and time necessary for detecting these trees.To simulate detection of water trees in this study, a mathematical model ofan XLPE cable and a water tree were developed. The complex water tree structure was simplified, based on two identified patterns of aventedtree. A Matlab simulation was performed to calculate and analyze the capacitance and resistance of a cable insulation layer,based on growth of a watertree. Capacitance size increased about 0.025×10^-13[Farads/mm] compared to normal when the tree area of the cable was advanced to 95% of the insulation layer. The resistance value decreased by about 0.5×10¹⁶[ohm/m]. These changesand changesshowninaBurkes paper physical modeling simulation are similar.The value of mathematical modeling for detecting water trees and damage to underground cables has been demonstrated.

• Korean Journal of Environment and Ecology
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• v.15 no.4
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• pp.394-400
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• 2002

A mixed forest community of broad-leaved trees in Guryongsan area was studied to determine the adequate number of plots of tree and shrub strata for investigating forest community structure. Fifteen 10m$\times$10m plots were set up in the tree stratum and fifteen 5m$\times$5m plots were set up in the shrub stratum. Species-area curves and performance curves were made from vegetation analysis of the plots. In tree stratum, the minimum number of plots where a given percentage increase in number of plots produced less than the same percentage in number of species was five. In tree stratum, minimum number of plots where a given percentage increase in nuts her of plots produced less than the half of the percentage increase in number of species was ten. In tree stratum, minimum number of plots where the dominant species was distinguished from the subdominant species was four In tree stratum. minimum number of plots where the subdominant species were distinguished from each other was eight. In tree stratum, the difference of species diversity(H') between seven or more plots and total fifteen plots was less than 0.05 Similarity index was more than 80% between aye or more plots and total fifteen plots, and more than 90% between nine or more plots and total fifteen plots. In shrub stratum, the minimum number of plots where a given percentage increase in number of plots produced less than the same percentage in number of species was five . In shrub stratum, the minimum number of plots where a given percentage increase in number of plots produced less than the half of the percentage increase in number of species was twelve. In shrub stratum. minimum number of plots where the dominant species was distinguished from the subdominant species was four. In shrub stratum, the minimum number of plots where the subdominant species were distinguished from each other was thirteen. In shrub stratum, the difference of species diversity(H') between six or more plots and total fifteen plots was less than 0.05. Similarity index was more than 80% between five or more plots and total fifteen plots, and more than 90% between nine or more plots and total fifteen plots. It may be given as a conclusion that adequate number of 10m$\times$10m plots for the tree stratnm was about 5 in general acse and 10 in case of requiring more accuracy, and that the adequate number of 5m$\times$5m plots for ahrub stratum was about 5 in general case and 13 in case of requiring more accuracy.

• Proceedings of the Korean Society of Computational and Applied Mathematics Conference
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• 2003.09a
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• pp.16.1-16
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• 2003

A subset S of vertices of a graph G is independent if no two vertices of S are adjacent by an edge in G. Also we say that S is maximal independent if it is contained In no larger independent set in G. A planted plane tree is a tree that is embedded in the plane and rooted at an end-vertex. A (k＋1) -valent tree is a planted plane tree in which each vertex has degree one or (k＋1). We classify maximal independent sets of (k＋1) -valent trees into two groups, namely, type A and type B maximal independent sets and consider specific independent sets of these trees. We study relations among these three types of independent sets. Using the relations, we count the number of all maximal independent sets of (k＋1) -valent trees with n vertices of degree (k＋1).

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.4
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• pp.375-381
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• 2014

Data mining is a process of discovering useful patterns or information from large amount of data. Decision tree is one of the data mining algorithms that can be used for both classification and prediction and has been widely used for various applications because of its flexibility and interpretability. Decision trees for classification generally generate a number of rules that belong to one of the predefined category and some rules may belong to the same category. In this case, it is necessary to determine the significance of each rule so as to provide the priority of the rule with users. The purpose of this paper is to propose a rule selection method in classification tree models that accommodate the umber of observation, accuracy, and effectiveness in each rule. Our experiments demonstrate that the proposed method produce better performance compared to other existing rule selection methods.

• Journal of information and communication convergence engineering
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• v.20 no.3
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• pp.160-165
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• 2022

This paper proposes an efficient method of reconstructing interconnections when the terminals of each plane change in real-time situations where randomly divided planes are interconnected. To connect all terminals when the terminals of each plane are changed, we usually reconstruct the interconnections between all terminals. This ensures a minimum connection length, but it takes considerable time to reconstruct the interconnection for the entire terminal. This paper proposes a solution to obtain an optimal tree close to the minimum spanning tree (MST) in a short time. The construction of interconnections has been used in various design-related areas, from networks to architecture. One of these areas is an ad hoc network that only consists of mobile hosts and communicates with each other without a fixed wired network. Each host of an ad hoc network may appear or disappear frequently. Therefore, the heuristic proposed in this paper may expect various cost savings through faster interconnection reconstruction using the given information in situations where the connection target is changing.

• The Korean Journal of Ecology
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• v.7 no.4
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• pp.185-193
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• 1984

Regneration process of Abies koreana-Pinus koraiensis community consisted of a subalpione coniferous forest in Mt. Jiri, Korea, was studied in relation to age structure, especially to gap formation. The tall-tree layer (ca. 6.5m) is dominated by Abies koreana and Pinus koraiensis, while lower layer by the sapling and juveniles of A. koreana and Picea jezoensis below 2m tall. The ranges of DBH in A. koreana, P. koraiensis and P. jezonesis were 11.8cm~26.4m, 11.7cm~24.5 cm and 18.2cm~21.7 cm, respectively. The trees below 130 cm tall had contagious distribution, while tall and subtall trees had uniform distribution. The average tree ages of A. koreana, P. koraieniensis and P. jezoensis were 60~70 years, 70~80 years and 70~90 years, respectively. The saplings and juveniles below 20 years in tree ages were occupied over 80% of total trees. The coniferous trees in the gaps or around dead trees were composed of sapligs and juveniles which had emerged or invaded about 20 years before and after the gap formation. The Betula type regeneration of the coniferous forest took place in gaps which orginated from the failing down of a single or a few trees by longevity. Accordingly, it is clear that the subalpine coniferous forest composed of A. koreana of A. koreana, P. koraiensis and P. jezoensis in Mt. jiri was supporting by the regeneration pattern of Betula type.

• 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.

• Journal of Korea Society of Digital Industry and Information Management
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• v.19 no.1
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• pp.109-118
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• 2023

Data-based analysis methods have become used more for estimating or predicting housing prices, and neural network models and decision trees in the field of big data are also widely used more and more. Neural network models are often evaluated to be superior to existing statistical models in terms of estimation or prediction accuracy. However, there is ambiguity in determining the input feature of the input layer of the neural network model, that is, the type and number of input features, and decision trees are sometimes used to overcome these disadvantages. In this paper, we evaluate the existing methods of using decision trees and propose the method of using decision trees to prioritize input feature selection in neural network models. This can be a complementary or combined analysis method of the neural network model and decision tree, and the validity was confirmed by applying the proposed method to house price estimation. Through several comparisons, it has been summarized that the selection of appropriate input characteristics according to priority can increase the estimation power of the model.

• The Korean Journal of Mycology
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• v.46 no.3
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• pp.235-239
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• 2018

Basil (Ocimum spp.) is a popular herb grown worldwide. During the past fifteen years, a downy mildew pathogen has caused considerable damage to basil cultivations. In August 2017, downy mildew disease symptoms were found on Basil Tree (or long foot Basil Tree), which was developed by the grafting of two basil varieties and is a continuous harvest plant with a woody trunk. The present study reports the occurrence of downy mildew disease in basil Tree and identifies the causal pathogen, as Peronospora belbahrii.