• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.7
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• pp.1218-1224
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• 2016

This paper presents the results of a study on the effect of surface modified alumina nanocomposites on electrical tree growth in epoxy insulation. Treeing experiments were conducted at a fixde AC voltage (500kV/mm, 10kV/60Hz)on unfilled epoxy sample as well as epoxy nanocomposites of 4 types with different loading and surface modified GDE gram. Time for tree growth as well as tree propagation length were studied. The results show that there is a significant improvement tree propagation time compare unfilled epoxy to epoxy nano alumina composites. Different tree propagation shapes as well as slower tree growth with 4 types nano alumina composites were observed.

• Journal of Korea Multimedia Society
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• v.20 no.11
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• pp.1793-1802
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• 2017

In the recent years, IT and Network Technology has rapidly advanced environment in accordance with the needs of the times, the usage of the smart learning service is increasing. Smart learning is extended from e-learning which is limited concept of space and place. This system can be easily exposed to the various security threats due to characteristic of wireless service system. Therefore, this paper proposes the improvement methods of smart learning system security by use of faults analysis methods such as the FTA(Fault Tree Analysis) and FMECA(Failure Mode Effects and Criticality Analysis) utilizing the consolidated analysis method which maximized advantage and minimized disadvantage of each technique.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.6
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• pp.698-704
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• 2011

This study aims to facilitate and increase the performance of the Traffic Analysis System which receives the location information of vessels sailing along the coast all over the country in real time and analyzes the vessels' sailing situation. Especially, the research has a signification that the system is designed with the application of Quad-Tree and R-Tree data structure in order for system users to search necessary information quickly and effectively, and it verifies the improvement of the performance by showing experiment results comparing the existing Traffic Analysis System to newly upgraded Traffic Analysis System.

• 한국데이터정보과학회:학술대회논문집
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• 2005.04a
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• pp.164-173
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• 2005

Data mining is the method to find useful information for large amounts of data in database. It is used to find hidden knowledge by massive data, unexpectedly pattern, relation to new rule. The methods of data mining are decision tree, association rules, clustering, neural network and so on. The decision tree approach is most useful in classification problems and to divide the search space into rectangular regions. Decision tree algorithms are used extensively for data mining in many domains such as retail target marketing, fraud detection, data reduction and variable screening, category merging, etc. We analyze waste database united with local information using decision tree techniques for environmental information. We can use these decision tree outputs for environmental preservation and improvement.

• Journal of KIISE
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• v.42 no.4
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• pp.522-529
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• 2015

Ever since the R-tree was proposed to index multi-dimensional data, many efforts have been made to improve its query performances. One common trend to improve query performance is to parallelize query processing with the use of multi-core architectures. To this end, a GPU-base R-tree has been recently proposed. However, even though a GPU-based R-tree can exhibit an improvement in query performance, it is limited in its ability to handle large volumes of data because GPUs have limited physical memory. To address this problem, we propose MGR-tree (Multi-GPU R-tree), which can manage large volumes of data by dividing nodes into multiple GPUs. Our experiments show that MGR-tree is up to 9.1 times faster than a sequential search on a GPU and up to 1.6 times faster than a conventional GPU-based R-tree.

• The KIPS Transactions:PartA
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• v.12A no.2 s.92
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• pp.109-116
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• 2005

In this paper, we introduce the method that a user analyses the similarity of the two programs by using keyword from the syntactic tree, created after the syntax analysis, and its implementation. The main advantage of the method is the performance improvement through using only keyword of syntax tree. In the paper, we propose the similarity evaluation model and how we extract keyword from syntax tree. In addition, we also show the improvement in the performance in analysis and in the system's structure. We expect that our system will be utilized in the similarity evaluation in text and XML documents.

• Journal of KIISE
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• v.41 no.10
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• pp.792-798
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• 2014

In spatial databases, R-tree is one of the most widely used indexing structures and many variants have been proposed for its performance improvement. Among these variants, Hilbert R-tree is a representative method using Hilbert curve to process large amounts of data without high cost split techniques to construct the R-tree. This Hilbert R-tree, however, is hardly applicable to large-scale applications in practice mainly due to high pre-processing costs and slow bulk-load time. To overcome the limitations of Hilbert R-tree, we propose a novel approach for parallelizing Hilbert mapping and thus accelerating bulk-loading of Hilbert R-tree on GPU memory. Hilbert R-tree based on GPU improves bulk-loading performance by applying the inversed-cell method and exploiting parallelism for packing the R-tree structure. Our experimental results show that the proposed scheme is up to 45 times faster compared to the traditional CPU-based bulk-loading schemes.

• Journal of Forest and Environmental Science
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• v.25 no.2
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• pp.111-118
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• 2009

Multiple shoot induction and plant regeneration using apical bud and nodal explants of 100 year old tree of Anthocephalus cadamba, an important sacred and medicinal tree in India was achieved for the first time. Aseptic explants cultured in Murashige and Skoog (MS) medium augmented with different concentrations of BAP (0.1, 0.5, 1.0, 2.5, 5.0 and 10 mg/l), when maintained for 60 days, healthy shoots were induced in presence of BAP (1 mg/l). Lower concentrations of BAP (0.1 - 0.5 mg/l) induced only one shoot per explant. Increase in number of shoots per explant was observed in presence of higher concentrations of BAP (2.5, 5.0 and 10 mg/l). However, elongation of shoots was completely inhibited. Bud break and shoot regeneration was largely associated with seasonal factors. Apical buds cultured during June to August exhibited early bud break within two weeks of initial culture. In rest of the months, bud break and shoot regeneration was very slow irrespective of the various concentrations of BAP used in the medium. Explants sourced from three different maturity levels of shoots indicated that actively growing shoots from the mother plant with 1 - 2 nodal segments was more suitable for culture initiation than the explants collected from mature shoots at dormant stage. Regenerated shoots with 2 - 3 pairs of leaves when transferred to half strength MS medium fortified with IBA (1 mg/l), 60% of the shoots induced healthy roots, indicating the possibility of large scale micropropagation.

• Journal of Information Processing Systems
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• v.9 no.2
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• pp.315-332
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• 2013

This paper presents an approach for improving the use of VP-tree in video indexing and searching. A vantage-point tree or VP-tree is one of the metric space-based indexing methods used in multimedia database searches and data retrieval. Instead of relying on the Euclidean distance as a measure of search space, the proposed approach focuses on the trigonometric inequality for compressing the search range, which thus, improves the search performance. A test result of using 10,000 video files shows that this method reduced the search time by 5-12%, as compared to the existing method that uses the AESA algorithm.

• IE interfaces
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• v.15 no.3
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• pp.241-246
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• 2002

Some extensions of minimum spanning tree problem are NP-hard problem in which polynomial-time solutions for them do not exist. Because of their complexity, recently some researcher have used the genetic algorithms to solve them. In genetic algorithm approach the Prufer number is usually used to represent a tree. In this paper we discuss the problem of the Prufer number encoding method and propose an improved genetic operation. Using a numerical comparison we demonstrate the excellence of the proposed method.