• Journal of Korea Spatial Information System Society
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• v.6 no.1 s.11
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• pp.19-29
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• 2004

Recently, studies have been performed to improve the cache performance of the R-Tree in main memory. A general mothed to improve the cache performance of the R-Tree is to reduce size of an entry so that a node can store more entries and fanout of it can increase. However, this method generally requites additional process to reduce information of entries and do not support incremental updates. In addition, the cache miss always occurs on moving between a parent node and a child node. To solve these problems efficiently, this paper proposes and evaluates the PR-Tree that is an extended R-Tree indexing method using prefetching in main memory. The PR-Tree can produce a wider node to optimize prefetching without additional modifications on the R-Tree. Moreover, the PR-Tree reduces cache miss rates that occur in moving between a parent node and a child node. In our simulation, the search performance, the update performance, and the node split performance of the PR-Tree improve up to 38%. 30%, and 67% respectively, compared with the original R-Tree.

• The KIPS Transactions:PartD
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• v.13D no.4 s.107
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• pp.463-476
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• 2006

R-trees have been traditionally optimized for the I/O performance with the disk page as the tree node. Recently, researchers have proposed cache-conscious variations of R-trees optimized for the CPU cache performance in main memory environments, where the node size is several cache lines wide and more entries are packed in a node by compressing MBR keys. However, because there is a big difference between the node sizes of two types of R-trees, disk-optimized R-trees show poor cache performance while cache-optimized R-trees exhibit poor disk performance. In this paper, we propose a cache and disk optimized R-tree, called the PR-tree (Prefetching R-tree). For the cache performance, the node size of the PR-tree is wider than a cache line, and the prefetch instruction is used to reduce the number of cache misses. For the I/O performance, the nodes of the PR-tree are fitted into one disk page. We represent the detailed analysis of cache misses for range queries, and enumerate all the reasonable in-page leaf and nonleaf node sizes, and heights of in-page trees to figure out tree parameters for best cache and I/O performance. The PR-tree that we propose achieves better cache performance than the disk-optimized R-tree: a factor of 3.5-15.1 improvement for one-by-one insertions, 6.5-15.1 improvement for deletions, 1.3-1.9 improvement for range queries, and 2.7-9.7 improvement for k-nearest neighbor queries. All experimental results do not show notable declines of the I/O performance.

• 한국공간정보시스템학회:학술대회논문집
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• 2003.11a
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• pp.123-128
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• 2003

최근 프로세서와 메인 메모리간의 속도 차이가 커지면서 캐시 실패가 메인 메모리에서 동작하는 R-Tree의 성능 저하에 미치는 영향이 커짐에 따라 캐시 실패를 줄여 캐시 성능을 개선하려는 연구가 많이 진행되고 있다. 일반적인 캐시 성능 개선 방법은 엔트리 정보를 줄설 노드에 더 않은 엔트리를 저장함으로써 펜-아웃(fanout)을 증가시키고 캐시 실패를 최소화한다. 그러나 이러한 방법은 엔트리 정보를 줄이는 추가 연산으로 인해 갱신 성능이 떨어지고, 노드간 이동시 발생하는 캐시 실패는 여전히 해결하지 못하고 있다. 본 논문은 이를 해결하기 위해 선반입(prefetching)을 적용한 확장된 R-Tree인 PR-tree(Prefetching R-Tree)를 제안하고 평가하였다 PR-Tree는 펜-아웃을 증가시키고 트리의 높이를 낮추기 위해 실제 캐시 라인의 정수 배인 노드를 생성하고, 선반입을 적용하여 노드 캐시로 인한 메모리 지연을 최소화하였다. 또한 접근할 노드를 선반입하여 노드간 이동시 발생하는 캐시 실패도 최소화하였다. PR-Tree는 실험에서 R-Tree보다 검색 연산에서 최대 38%의 성능 향상을 보였으며, 갱신 연산에서도 최대 30%의 성능 향상을 보였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.769-772
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• 2007

공간 데이터의 효율적인 처리는 현대의 멀티미디어 데이터베이스에 있어서 대단히 중요한 역할을 하고 있다. 많은 응용분야에서 방대한 양의 공간 데이터는 보조기억장치(예: disk)에 저장이 되어 사용이 되고 공간 색인구조의 처리는 I/O에 대한 의존도가 크므로, I/O 연산의 병렬처리는 공간 색인구조의 질의반응시간을 현저하게 줄일 수 있다. 본 논문에서는 PR-tree라는 병렬형 공간 색인구조를 제안한다. PR-tree는 MXR-tree에 비해 높은 공간활용도와 빠른 처리시간을 보임으로써 공간 데이터베이스를 위한 효율적인 색인구조로 사용이 될 것으로 기대된다.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10b
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• pp.117-119
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• 1998

대용량의 데이터를 다루는 지리정보 시스템은 I/O가 시스템의 병목현상을 발생시킨다. 따라서, I/O의 병렬화로 GIS의 데이터 요구를 만족시키려는 연구가 이루어져 왔다. PR(Parallel R-tree)[1]도 이러한 연구에 속한다. 한편, 지리 정보 시스템의 질의는 영역질의가 대부분이다. 영역질의는 특성상 인접한 객체들의 동시에 요구한다. 그러므로, 인접한 데이터를 물리적으로 인접하게 배치하면 I/O의 성능이 향상된다. 본 논문에서는 인접한 객체를 물리적으로 인접한 위치에 저장하는 방식인 EPR(Enhanced PR)기법과 단말노드 구조를 제안하고 그 성능을 평가하였다.

• Journal of Forest and Environmental Science
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• v.29 no.3
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• pp.194-199
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• 2013

The aim of the present study was to assess the effect of transitional boundary on community composition and soil carbon stock. Five vegetation types were recognized horizontally along the transitional strip based on the dominance of tree species i.e., Pure Anogeissus latifolia forest (P.AL), mixed Pinus roxburghii and Lannea coromandelica forest (M.PR&LC), pure Pinus roxburghii forest (P.PR), mixed Pinus roxburghii and Lannea coromandelica (M.PR&LC) and pure Anogeissus latifolia forest (P.AL). The results revealed that Anogeissus latifolia was reported dominant tree in the outer transitional boundaries of the forest, which reduced dominance of trees towards middle where Pinus roxburghii was found dominant. The soil carbon stock was reported higher in the Anogeissus latifolia dominant forest and reduced with the dominance of Pinus roxburghii in the middle site. Both the species are growing close to one another and competing for survival, but the aggressive nature of Anogeissus latifolia particular in this region may change new growth of Pinus roxburghii and will enhance soil carbon stock. But high anthropogenic pressure on Anogeissus latifolia tree species could be limited chance to further its flourish.

• Geomechanics and Engineering
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• v.29 no.5
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• pp.523-533
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• 2022

Several prediction model of penetration rate (PR) of tunnel boring machines (TBMs) have been focused on applying to design stage. In construction stage, however, the expected PR and its trends are changed during tunneling owing to TBM excavation skills and the gap between the investigated and actual geological conditions. Monitoring the PR during tunneling is crucial to rescheduling the excavation plan in real-time. This study proposes a sequential prediction method applicable in the construction stage. Geological and TBM operating data are collected from Gunpo cable tunnel in Korea, and preprocessed through normalization and augmentation. The results show that the sequential prediction for 1 ring unit prediction distance (UPD) is R²≥0.79; whereas, a one-step prediction is R²≤0.30. In modeling algorithm, a gradient boosted regression tree (GBRT) outperformed a least square-based linear regression in sequential prediction method. For practical use, a simple equation between the R² and UPD is proposed. When UPD increases R² decreases exponentially; In particular, UPD at R²=0.60 is calculated as 28 rings using the equation. Such a time interval will provide enough time for decision-making. Evidently, the UPD can be adjusted depending on other project and the R² value targeted by an operator. Therefore, a calculation process for the equation between the R² and UPD is addressed.

• Journal of the Korea Computer Industry Society
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• v.6 no.3
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• pp.539-550
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• 2005

The spanning tree, which is being used the most widely in indoor wiring network, is chosen for the network topology of the optimal LAN design. To apply a spanning tree to GA, the concept of $Pr\ddot{u}fer$ numbers is used. $Pr\ddot{u}fer$ numbers can express he spanning tree in an efficient and brief way, and also can properly represent the characteristics of spanning trees. This paper uses Pareto Stratum-Niche Cubicle(PS-NC) GA by complementing the defect of the same priority allowance in non-dominated solutions of pareto genetic algorithm(PGA). By applying the PS-NC GA to the LAN design areas, the optimal LAN topology design in terms of minimizing both message delay time and connection-cost could be accomplished in a relatively short time. Numerical analysis has been done for a hypothetical data set. The results show that the proposed algorithm could provide better or good solutions for the multi-objective LAN design problem in a fairly short time.

• The Plant Pathology Journal
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• v.20 no.2
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• pp.147-154
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• 2004

A simple and reliable procedure for RT-PCR detection of Apple stem pitting virus (ASPV), Cherry rasp leaf virus (CRLV), and Cherry necrotic rusty mottle virus (CNRMV) was developed. Two virus specific primer sets for each virus were found to specifically detect each virus among fourteen sets of designed oligonucleotide primers. Total RNAs extracted from healthy and from ASPV-,CRLV- and CNRMV-infected plant tissues were used to synthesize cDNA using oligo dT primer and then amplified by virus-specific primers for each virus. Each primer specifically amplified DNA fragments of 578 bp and 306 bp products for ASPV (prAS CP-C and prAS CP-N primers, respectively); 697 bp and 429 bp products for CRLV (prCR4 and prCR5-JQ3D3 primers, respectively); and 370 bp and 257 bp products for CNRMV (prCN4 and prCN6-NEG 1 primers, respec-tively) by RT-PCR. DNA sequencing of amplified DNA fragments confirmed the nature of each amplified DNA. Altogether, these results suggest that these virus specific primer sets can specifically amplify viral sequences in infected tissues and thus indicate that they can be used for specific detection of each virus.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.466-469
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• 2007

최근 늘어가는 통신 서비스에 대한 관심은 관련 이론 및 기술의 발전을 주도해 왔다. 이러한 통신 시스템에 관련한 문제들 중에 가장 근간이 되는 문제 중 하나는 최적 통신 걸침 나무 (OCST: Optimal Communication Spanning Tree) 문제이다. 본 논문에서는 이러한 최적 통신 걸침 나무 문제에 대한 해법으로 최적 통신 걸침 나무 문제에 적합한 새로운 유전자 표현법을 이용한 유전 알고리즘을 설계하여 구현한다. 제안하는 유전 알고리즘은 n개의 노드에 대해 n-2개의 숫자 열로 표현가능하다고 알려진 기존의 $Pr\ddot{u}fer$수 기반의 유전자 표현법을 개선하여 보다 더 최적 통신 걸침 문제에 적합하도록 고안한 새로운 유전자 표현법을 이용한다. 임의로 생성된 예제에 대한 수치 실험을 통해 통신시스템의 기본 문제 중 하나인 최적 통신 걸침 문제의 해법으로서의 제안 알고리즘의 유용성과 효율성을 확인한다.