• Korean Journal of Mathematics
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• 제20권2호
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• pp.255-261
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• 2012

Let $\mathcal{O}_n$ be the set of ordered labeled trees on $\{0,\;{\ldots},\;n\}$. A maximal decreasing subtree of an ordered labeled tree is defined by the maximal ordered subtree from the root with all edges being decreasing. In this paper, we study a new refinement $\mathcal{O}_{n,k}$ of $\mathcal{O}_n$, which is the set of ordered labeled trees whose maximal decreasing subtree has $k+1$ vertices.

• Korean Journal of Mathematics
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• 제21권4호
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• pp.495-502
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• 2013

Let $\mathcal{T}^{(p)}_n$ be the set of p-ary labeled trees on $\{1,2,{\ldots},n\}$. A maximal decreasing subtree of an p-ary labeled tree is defined by the maximal p-ary subtree from the root with all edges being decreasing. In this paper, we study a new refinement $\mathcal{T}^{(p)}_{n,k}$ of $\mathcal{T}^{(p)}_n$, which is the set of p-ary labeled trees whose maximal decreasing subtree has k vertices.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1995년도 추계학술대회발표논문집; 서울대학교, 서울; 30 Sep. 1995
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• pp.202-210
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• 1995

Given a tree T with a root node 0 having the capacity H and a profit $c_{v}$ and a demand $d_{v}$ on each node v of T, the capacitated subtree of a tree problem(CSTP) is to find a subtree of T containing the root that has the maximum total profit, the sum of profits over the subtree, and also satisfies the constraint of which the sum of demands over the subtree must be less than or equal to H. We first define the so-called critical item for CSTP and find an upper bound on the linear programming relaxation of CSTP. We then present our branch and bound algorithm for solving CSTP and finally report the computational results on a set of randomly generated test problems.s.s.

• Journal of Computing Science and Engineering
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• 제6권2호
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• pp.127-140
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• 2012

In this paper, we focus on efficient construction of tightest matched subtree (TMSubtree) results, for keyword queries on extensible markup language (XML) data, based on smallest lowest common ancestor (SLCA) semantics. Here, "matched" means that all nodes in a returned subtree satisfy the constraint that the set of distinct keywords of the subtree rooted at each node is not subsumed by that of any of its sibling nodes, while "tightest" means that no two subtrees rooted at two sibling nodes can contain the same set of keywords. Assume that d is the depth of a given TMSubtree, m is the number of keywords of a given query Q. We proved that if d ${\leq}$ m, a matched subtree result has at most 2m! nodes; otherwise, the size of a matched subtree result is bounded by (d - m + 2)m!. Based on this theoretical result, we propose a pipelined algorithm to construct TMSubtree results without rescanning all node labels. Experiments verify the benefits of our algorithm in aiding keyword search over XML data.

• 대한산업공학회지
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• 제22권3호
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• pp.485-498
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• 1996

For a tree T rooted at a concentrator location in a telecommunication system, we assume that the capacity H for the concentrator is given and a profit $c_v$, and a demand $d_v$, on each node $\upsilon$ of T are also given. Then, the capacitated subtree of a tree problem (CSTP) is to find a subtree of T rooted at the concentrator location so as to maximize the total profit, the sum of profits over the subtree, under the constraint satisfying that the sum of demands over the subtree does not exceed H. In this paper, we develop a pseudopolynomial-time algorithm for CSTP, the depth-first dynamic programming algorithm. We show that a CSTP can be solved by our algorithm in $\theta$ (nH) time, where n is the number of nodes in T. Our algorithm has its own advantage and outstanding computational performance incomparable with other approaches such as CPLEX, a general integer programming solver, when it is incorporated to solve a Local Access Telecommunication Network design problem. We report the computational results for the depth-first dynamic programming algorithm and also compare them with those for CPLEX. The comparison shows that our algorithm is competitive with CPLEX for most cases.

• 한국환경복원기술학회지
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• 제18권3호
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• pp.65-77
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• 2015

The urban park has important functions as a habitat for wildlife as well as open space of rest and community for people. This study was carried out to find what factors of structure and vegetation of urban parks could affect forest bird species diversity in Cheonan city. The study surveyed bird and vegetation species in 26 urban parks, Cheonan city. A correlation analysis and multiple linear regressions were performed to test whether habitat structure and vegetation were the major correlate with species diversity. The results showed the Dujeong park was the most high bird species diversity (H' = 2.13), and the Dujeong-8 park (H' = 2.02) and the Cheongsa park (H' = 1.73) were considerably higher than the other urban parks. The variables that were strongly correlated with bird species diversity were park area, number of subtree species, canopy of shrub, number of shrub species, shape index, canopy of subtree, canopy of tree, and impervious surface ratio. The regression of bird species diversity against the environmental variables showed that 3 variables of park area, canopy of subtree, and canopy of tree were included in the best model. Model variable selection was broadly similar for the 5 optimal models. It means park area and multi-layer vegetation were the most consistent and significant predictor of bird species diversity, because urban parks were isolated by built-up areas. Especially the subtree coverage that provides shelter and food for forest birds was an important variable. Therefore, to make parks circular-shaped and abundant multi-layer vegetation, which could be a buffer to external disturbances and improve the quality of habitats, may be used to enhance species diversity in creation and management of urban parks.

• 한국경영과학회지
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• 제22권3호
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• pp.81-98
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• 1997

Given a rooted tree T with profits and node demands, the capacitated subtree of a tree problem (GSTP) consists of finding a rooted subtree of maximum profit, subject to having total demand no larger than the given capacity H. We first define the so-called critical item for CSTP and find an upper bound on the optimal value of CSTP in O(n$^{2}$) time, where n is the number of nodes in T. We then present our branch and bound algorithm for solving CSTP and illustrate the algiruthm by using an example. Finally, we implement our branch-and-bound algorithm and compare the computational results with those for both CPLEX and a dynamic programming algorithm. The comparison shows that our branch-and-bound algorithm performs much better than both CPLEX and the dynamic programming algorithm, where n and H are the range of [50, 500] and [5000, 10000], respectively.

• 한국환경복원기술학회지
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• 제14권1호
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• pp.57-65
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• 2011

The composition of species for each community of Quercus by vegetation and soil survey, the community classification by TWINSPAN, the structural characteristics of communities were used and analyzed during the period of 2000~2004 for Quercus mongolica forest. And the resulting suggestions for a subsequent planting model for forest are as follows. The Quercus mongolica community had the highest importance value for Quercus mongolica followed sequentially by Acer pseudosieboldianum, Acer mono, Rhododendron schlippenbachii, Tilia amurensis, Fraxinus rhynchophylla, and Fraxinus sieboldiana. As a result of suggesting a planting modeling for the Quercus mongolica communities in the areas with the warmth index of both $60.90{\sim}79.79^{\circ}C$ and $53.96{\sim}64.82^{\circ}C$, Quercus mongolica was absolutely dominant in case of the subtree layer for the accompaniment species of distribution in the planting modeling by tree layer in the two areas depending on the warmth index, while there were distinct differences shown in case of the lower tree layer. While Acer pseudosieboldianum, Tilia amurensis, Fraxinus rhynchophylla, Sorbus alnifolia, Acer mono, etc. were appeared in the subtree layer for the areas with the warmth index of $60.90{\sim}79.79^{\circ}C$. Cornus controversa, Quercus mongolica, Fraxinus sieboldiana, etc. were many appeared in the subtree layer for the areas with the warmth index of $53.96{\sim}64.82^{\circ}C$. And, when we made ecological Quercus mongolica community, subtree layer planting is different by warmth index.

• 환경영향평가
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• 제20권2호
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• pp.151-162
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• 2011

The purpose of this study is suggest to restoration model of Pinus thunbergii in Saha-gu, Busan Metropolitan City. The result of this study is summarized as follows; As the results of this study, vegetation restoration model is presented by separating community planting and edge planting. The community planting species of tree layer were Pinus thunbergii and Quercus acutissima and Quercus dentata and Quercus serrata and Quercus alienna and Quercus variabilis. The community planting species of subtree layer were Platycarya strobilacea and Prunus sargentii and Styrax japonica and Eurya japonica and Morus bombycis. The community planting species of shrub layer are Ulmus pavifolia and Ulmus davidiana and Lindera obtusiloba and Elaeagnus macrophylla and Mallotus japonicus and Ligustrum obtusifolium and Sorbus alnifolia and Rhus trichocarpa and Zanthoxylum schinifolium and Rosa wichuraiana and Rhus chinensis and Viburnum erosum and Rhododendron mucronulatum and Rhododendron yedoense and Indigofera pseudotinctoria. And the planting species of edge vegetation are Japanese Angelica and Symplocos chinensis and Pittosporum tobira and Lespedeza maximowiczii and Lespedeza bicolor and Rubus coreanus and Rubus idaeus and Vitis thunbergii and Ampelopsis brevipedunculata and Rosa multiflora. Considering the population of individuals up to layers in each $400m^2$ area, it was composed of 24 in tree layer, 35 in subtree layer, 410 in shrub layer and 34% herb layer in the Pinus thunbergii community. And the average of breast-high area and canopy area was $10,852cm^2$ in tree layer, in subtree layer $1,546cm^2$, in shrub layer $1,158,660cm^2$. The shortest distance between trees was calculated as 2.0m in tree layer, 1.9m in subtree layer.

• 한국정보과학회논문지:데이타베이스
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• 제32권2호
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• pp.177-192
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• 2005

본 논문에서는 XML 데이타를 릴레이션으로 분할 저장할 경우, 분할된 XML 데이타로부터 질의 결과 XML 문서를 재구성하는데 소모되는 질의 처리비용을 줄이기 위한 구조적 중복 방법을 소개한다. 기본 아이디어는 주어진 질의 패턴을 분석하여, 적절한 데이타들을 중복시킴으로서 질의 처리 성능을 향상시키는 것이다. 이러한 구조적 중복 방법으로 실질적으로 유효할 수 있는 ID, VALUE, SUBTREE의 세 가지 유형의 특성을 분석하였다. 본 논문에서는 추가적으로 주어진 XML 데이타와 질의들이 매우 크고 복잡할 경우 최적의 중복 집합을 팎는 것이 매우 어려운 작업이 될 수 있으므로, 이를 위한 경험적 탐색 방법을 소개한다. 마지막으로 몇 가지 실험을 통하여, 중복 데이타를 사용함으로 발생하는 XML 질의 처리비용과 제안된 탐색 방법의 효율성을 분석한다. 중복 데이타를 사용함으로 XML 판독 질의는 빨라지지만, XML 갱신 질의는 중복 데이타의 갱신 일관성 비용 때문에 느려지는 것은 당연하다. 하지만 실험 결과는 매우 과도한 갱신 비용의 경우에도 in-place ID 중복은 효율적이며, 갱신 비용이 매우 과도하지만 않다면 multiple-place SUBTREE 중복은 판독 질의 처리 성능을 크게 향상시킬 수 있음을 보여주었다.