• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.9
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• pp.1867-1879
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• 1997

DREAM-S is a distributed main-memory database system for the real-time processing of shared operational datra in ATM switching systems. DREAM-S has a client-server architecture in which only the server has the diskstorage, and provides the T-Tree index structure for efficient accesses to the data. We propose a recovery technique for the T-Tree index structre in DREAM-S. Although main-memory database system offer efficient access performance, the database int he main-memory may be broken when system failure such as database transaction failure or power failure occurs. Therfore, a recovery technique that recovers the database (including index structures) is essential for fault tolerant ATM switching systems. Proposed recovery technique relieves the bottleneck of the server processors disk operations by maintaining the T-Tree index structure only in the main-memory. In addition, fast recovery is guaranteed even in large number of client systems since the T-Tree index structure(s) in each system can be recovered cncurrently.

• Korean Journal of Microbiology
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• v.24 no.4
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• pp.400-405
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• 1986

We have constructed a phylogenetic tree for eleven species by comparing their tRNA sequences. The tree suggests that prokaryotes diverged very early before the emergence of animals. The fact that H. volcano, an archaebacterium, clusters with eukaryotes implied that eukaryotes did not diverge directly from thier common ancestor with eubacteria. The branching order of phage $T_{4}$ and phage $T_{5}$ indicates that they have diverged separately from thier hosts and they might have evolved independently. A correlation between nucleotide substitution in tRNAs and paleontological record was observed. We verified that our phylogenetic tree fits very well with traditional ones very well by imposing the molecular clock on the tree.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.4
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• pp.218-221
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• 2005

The present study was investigated in the Chittagong hill forest of Bangladesh to assess the feasibility of ginger cultivation under multipurpose forest and fruit tree species. There were three treatments such as i) ginger grown under open field condition, ie. full sunlight (T1), ii) ginger grown under Gamar tree (spacing of $90{\times}90cm$ (T2) and iii) ginger grown under guava tree (spacing $180{\times}180cm$) tree (T3). The experiment was laid out in randomized block design (RBD) and each treatment was replicated three times. From data it was observed that some morphological parameters of ginger such as plant height, number of leaves per plant, leaf length and leaf breadth were higher in the treatments T2 and T3 as compared to the treatment T1. A positive and linear relationship was observed between the weight of rhizome and yield of ginger which caused the highest yield of ginger ($23.63Mg\;ha^{-1}$) under guava tree species at partial shaded condition in the T3 treatment ($180{\times}180cm$), whereas the lowest yield ($15.64Mg\;ha^{-1}$) was recorded in the T2 treatment when ginger was cultivated under Gamar tree species at closer spacing ($90{\times}90cm$). Therefore, it was revealed that partial shaded condition favoured the optimum growth and yield of ginger, whereas the dense shade from intensively planted tree species badly affected the dry matter production and yield of ginger.

• Journal of Korea Multimedia Society
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• v.12 no.10
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• pp.1374-1385
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• 2009

Recently, advances in speed of the CPU have for out-paced advances in memory speed. Main-memory access is increasingly a performance bottleneck for main-memory database systems. To reduce memory access speed, cache memory have incorporated in the memory subsystem. However cache memories can reduce the memory speed only when the requested data is found in the cache. We propose a new cache sensitive T-tree index structure called as $CST^*$-tree for range query search. The $CST^*$-tree reduces the number of cache miss occurrences by loading the reduced internal nodes that do not have index entries. And it supports the sequential access of index entries for range query by connecting adjacent terminal nodes and internal index nodes. For performance evaluation, we have developed a cost model, and compared our $CST^*$-tree with existing CST-tree, that is the conventional cache sensitive T-tree, and $T^*$-tree, that is conventional the range query search T -tree, by using the cost model. The results indicate that cache miss occurrence of $CST^*$-tree is decreased by 20~30% over that of CST-tree in a single value search, and it is decreased by 10~20% over that of $T^*$-tree in a range query search.

• Bulletin of the Korean Mathematical Society
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• v.59 no.2
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• pp.345-350
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• 2022

In this work, we confirm a weak version of a conjecture proposed by Hong Wang. The ideal of the work comes from the tree packing conjecture made by Gyárfás and Lehel. Bollobás confirms the tree packing conjecture for many small tree, who showed that one can pack T₁, T₂, …, $T_{n/\sqrt{2}}$ into Kn and that a better bound would follow from a famous conjecture of Erdős. In a similar direction, Hobbs, Bourgeois and Kasiraj made the following conjecture: Any sequence of trees T₁, T₂, …, T_n, with T_i having order i, can be packed into K_n-1,[n/2]. Further Hobbs, Bourgeois and Kasiraj [3] proved that any two trees can be packed into a complete bipartite graph K_n-1,[n/2]. Motivated by the result, Hong Wang propose the conjecture: For each k-partite tree T(𝕏) of order n, there is a restrained packing of two copies of T(𝕏) into a complete k-partite graph B_n+m(𝕐), where $m={\lfloor}{\frac{k}{2}}{\rfloor}$. Hong Wong [4] confirmed this conjecture for k = 2. In this paper, we prove a weak version of this conjecture.

• Bulletin of the Korean Mathematical Society
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• v.33 no.1
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• pp.119-126
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• 1996

In this paper we study the asymptotic behavior of the edge independence number of a random (n,n)-tree. The tools we use include the matrix-tree theorem, the probabilistic method and Hall's theorem. We begin with some definitions. An (n,n)_tree T is a connected, acyclic, bipartite graph with n light and n dark vertices (see [Pa92]). A subset M of edges of a graph is called independent(or matching) if no two edges of M are adfacent. A subset S of vertices of a graph is called independent if no two vertices of S are adjacent. The edge independence number of a graph T is the number $\beta_1(T)$ of edges in any largest independent subset of edges of T. Let $\Gamma(n,n)$ denote the set of all (n,n)-tree with n light vertices labeled 1, $\ldots$, n and n dark vertices labeled 1, $\ldots$, n. We give $\Gamma(n,n)$ the uniform probability distribution. Our aim in this paper is to find bounds on $\beta_1$(T) for a random (n,n)-tree T is $\Gamma(n,n)$.

• Kyungpook Mathematical Journal
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• v.52 no.4
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• pp.513-519
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• 2012

For a spanning tree T of a connected graph ${\Gamma}$ and for a labelling ${\phi}$: E(T) ${\rightarrow}$ {+,-},${\phi}$ is called an alternating sign on a spanning tree T of a graph ${\Gamma}$ if for any cotree edge $e{\in}E({\Gamma})-E(T)$, the unique path in T joining both end vertices of e has alternating signs. In the present article, we prove that any graph has a spanning tree T and an alternating sign on T.

• Journal of Korea Game Society
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• v.13 no.4
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• pp.25-34
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• 2013

Spatial partitioning trees are needed for processing collision detections efficiently. In order to select split planes for spatial partitioning trees, the tree balance and the number of polygons overlapped with the split plane should be considered. In this paper, the heuristic algorithm controlling weight values of tree build criteria is proposed for spatial partitioning trees of 3D games. As the weight values are changed, tree build time, T-junction elimination time which can cause visual artifacts in splitting polygons overlapped with the split plane, rendering speed (frame per second: FPS) according to tree balance are analysed under 3D game simulations.

• Journal of applied mathematics & informatics
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• v.37 no.3_4
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• pp.163-176
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• 2019

Given a distribution of pebbles on the vertices of a connected graph G, a pebbling move is defined as the removal of two pebbles from some vertex and the placement of one of those pebbles at an adjacent vertex. The t-pebbling number, $f_t(G)$, of a connected graph G, is the smallest positive integer such that from every placement of $f_t(G)$ pebbles, t pebbles can be moved to any specified vertex by a sequence of pebbling moves. A graph G has the 2t-pebbling property if for any distribution with more than $2f_t(G)$ - q pebbles, where q is the number of vertices with at least one pebble, it is possible, using the sequence of pebbling moves, to put 2t pebbles on any vertex. In this paper, we determine the t-pebbling number for the middle graph of a complete binary tree $M(B_h)$ and we show that the middle graph of a complete binary tree $M(B_h)$ satisfies the 2t-pebbling property.

• Bulletin of the Korean Mathematical Society
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• v.57 no.1
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• pp.245-250
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• 2020

Let γt(G) and τ(G) denote the total domination number and vertex cover number of graph G, respectively. In this paper, we study the total domination number of the central tree C(T) for a tree T. First, a relationship between the total domination number of C(T) and the vertex cover number of tree T is discussed. We characterize the central trees with equal total domination number and independence number. Applying the first result, we improve the upper bound on the total domination number of C(T) and solve one open problem posed by Kazemnejad et al..