• Proceedings of the Korea Contents Association Conference
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• 2010.05a
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• pp.13-15
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• 2010

이동객체의 공간 데이터를 색인하기 위해 검색성능이 뛰어난 R-tree구조가 많이 활용된다. 최근 R-tree를 B+-tree처럼 인접한 단말노드 간의 연결을 통해 질의 처리를 수행하는 ISR-tree와 ISG-index가 제안되었다. 이 기법들은 MBR (Minimum Boundary Rectangle) 간의 인접한 이웃 노드를 결정하기 위해 보르노이 다이어그램(Voronoi Diagram)을 이용한다. MBR을 대상으로 하는 보르노이 다이어그램은 매우 복잡한 연산과정을 거친다. 본 논문에서는 점을 대상으로 하는 보르노이 다이어그램 연산을 활용한 인접한 이웃 MBR을 연산하는 기법을 제안한다. 각 MBR의 꼭지점들을 기준으로 보르노이 다이어그램을 만들 경우, 인접한 MBR의 꼭지점들의 보르노이 셀이 항상 인접한 것을 알아내었고, 이를 활용한다. 제안하는 기법의 우수성을 증명하기 위해 기존의 기법과 비교하여 성능평가를 수행하였다.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.157-159
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• 2007

The conventional hard disk has been the dominant database storage system for over 25 years. Recently, hybrid systems which incorporate the advantages of flash memory into the conventional hard disks are considered to be the next dominant storage systems to support databases for desktops and server computers. Their features are satisfying the requirements like enhanced data I/O, energy consumption and reduced boot time, and they are sufficient to hybrid storage systems as major database storages. However, we need to improve traditional index node management schemes based on B-Tree due to the relatively slow characteristics of hard disk operations, as compared to flash memory. In order to achieve this goal, we propose a new index node management scheme called FNC-Tree. FNC-Tree-based index node management enhanced search and update performance by caching data objects in unused free area of flash leaf nodes to reduce slow hard disk I/Os in index access processes.

• 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..

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.2
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• pp.39-43
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• 2009

we studied and analyzed a tree mortality of 7 species(Pinus koraiensis etc) in surface forest fire area. In this results, the order of tree mortality was Cryptomeria japonica>Pinus koraiensis>Pinus densiflora>Pinus thunbergii>Larix leptolepis>Pinus rigida>Quercus. More damaged crown was higher tree mortality and more d.b.h was less tree mortality. Especially, oak trees in which a damage rate of crown was less 30% almost survived.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.11a
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• pp.454-457
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• 2011

본 연구에서는 소방시설의 성능위주의설계를 수행하기 위하여 ETA(Event Tree Analysis) 기법을 적용하는 방안을 고찰하였다. ETA기법에서는 화재시나리오를 사건(Event)의 인과관계로 된 각 단계의 사건으로 구성한다. 본 연구에서는 ETA에서 구성된 시나리오에 따른 심각도를 화재시뮬레이션과 피난 시뮬레이션을 통한 수행으로 사망자수를 도출하는 방안을 적용하였고, 각 시나리오의 빈도(확률)은 FTA(Fault Tree Analysis) 기법을 적용하여 분기 확률을 도출하도록 하였다. ETA에서 도출한 사망자수와 빈도를 이용하여 F-N 커브를 작성하여 위험도를 평가하여 소방설계의 보완 및 대책을 수립하는 방안을 제시하였다.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1481-1484
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• 1997

This paper describes a electrical tree simulation by fractal theory. Tree patterns produced by computer simulation with random numbers were studied from the point of view of fractal dimension. Tree patterns have a variety of shapes such as branch-like, bush-like, and quasi-bush-like trees. The patterns are determined by origins and probability ratio. The fractal dimensions have been measured a function of discharge number.

• Journal of Mushroom
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• v.16 no.4
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• pp.338-341
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• 2018

This study investigated the possibility of using pine tree sawdust in thinning-out tree as a substitute for poplar and douglas-fir tree sawdust in oyster mushroom cultivation. Mycelial growth was 10.8 cm in medium supplemented with 70% pine sawdust after 18 days of culture and 10.2 cm in control medium. Mycelial density showed high density with no significant difference between treatments. Fresh weight and diameter of fruiting bodies were slightly lower in medium supplemented with pine tree sawdust. The hardness of pine tree sawdust was slightly higher in the medium supplemented with 20% and 30% of pine tree sawdust. The L value showed a tendency to be higher in the pine added medium, but the a and b values d id not show any significant difference between the treatments. The yields of fruiting body were 157 g / 850 ml for the control and 170 g / 850 ml for the 40% added pine tree sawdust.

• Korean Journal of Microbiology
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• v.47 no.3
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• pp.268-274
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• 2011

Anabaena (Cyanobacteria, Nostocales) are important for water quality controls, because they are often responsible for freshwater green tides; moreover, some species are reported to produce hepatotoxin. In this study, we sequenced RNA polymerase beta subunit (rpoB) gene of Anabaena, and evaluated their sequences for the potential use of a molecular taxonomic marker in this taxon. Anabaena rpoB showed low DNA similarity and high genetic divergences when compared those of 16S rRNA, and the molecular differences were statistically significant (Student t-test, p<0.01). Parsimony analyses showed the rpoB gene evolves 4.8-fold faster than 16S rRNA. In addition, phylogeny of the rpoB gene separated each Anabaena strain more clearly compared with a 16S rRNA tree. These results suggest that the rpoB gene is a useful marker for the molecular phylogenetics and the species discrimination of Anabaena.

• The KIPS Transactions:PartD
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• v.8D no.2
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• pp.145-153
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• 2001

The Pyramid-Technique is based on mapping n-dimensional space data into one-dimensional data and expressing it as B-tree ; and by solving the problem of search time complexity the pyramid technique also prevents the effect \"phenomenon of dimensional curse\" which is caused by treatment of hypercube range query in n-dimensional data space. The Spherical Pyramid-Technique applies the pyramid method’s space division strategy, uses spherical range query and improves the search performance to make it suitable for similarity search. However, depending on the size of data and change in dimensions, the two above technique demonstrate significantly inferior search performance for data sizes greater than one million and dimensions greater than sixteen. In this paper, we propose a new index-structured PdR-Tree to improve the search performance for high dimensional data such as multimedia data. Test results using simulation data as well as real data demonstrate that PdR-Tree surpasses both the Pyramid-Technique and Spherical Pyramid-Technique in terms of search performance.

• Journal of the Korea Society of Computer and Information
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• v.10 no.5 s.37
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• pp.33-40
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• 2005

Recently So far Many low-cost mobile machinery have been produced. Those are being used for study and business. But those are some weak Points which are small-capacity storage and quite low-speed system. If we use general database programs or key-searching algorithm, It could decrease in performance of system. To solve those Problems, we applied CBDS(Compact Binary Digital Search) trie to mobile environment. As a result we could accomplish our goal which are quick searching and low-capacity indexing. We compared with some Java classes such as TreeSet to evaluation. As a result, the velocity of searching was a little slow than B-tree based TreeSet. But the storage space have been decreased by 29 percent. So I think that it would be practical use.