• Journal of Korean Society of Forest Science
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• v.101 no.4
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• pp.648-655
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• 2012

This research is aimed at suggesting the reasonable guideline for managing tree density of a therapeutic forest to enhance the therapeutic efficiency. To obtain visually preferable tree density for 4 coniferous tree species; Pinus koraiensis, Chamaecyparis obtusa, Pinus densiflora, Larix kaempferi, the simulations of tree density according to the 3 diameter classes are used. 250 people participated in questionnaire and 239 people of them were analyzed. The tree density preferences of 4 tree species are as follows; Pinus koraiensis forest; tree density for trees with Diameter (DBH=D)<25 cm about 816/ha, tree density for trees with 25=D<40 about 400/ha and tree density for trees with 40=D about 277/ha. Chamaecyparis obtusa forest; tree density for trees with D<25 about 625/ha, tree density for trees with 25=D<40 about 625/ha and tree density for trees with 40=D about 400/ha. Pinus densiflora forest; tree density for trees with D<25 about 816/ha, tree density for trees with 25=D<40 about 625/ha and tree density for trees with 40=D about 400/ha. Larix kaempferi forest; tree density for trees with D<25 about 625/ha, tree density for trees with 25=D<40 about 625/ha and tree density for trees with 40=D about 277/ha.

• Journal of KIISE:Information Networking
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• v.30 no.4
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• pp.520-534
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• 2003

In this paper, a performance evaluation model of the Fat-tree Network with the multiple-buffered crossbar switches is proposed and examined. Buffered switch technique is well known to solve the data collision problem of the switch network. The proposed evaluation model is developed by investigating the transfer patterns of data packets in a switch with output-buffers. Two important parameters of the network performance, throughput and delay, are then evaluated. The proposed model takes simple and primitive switch networks, i.e., no flow control and drop packet, to demonstrate analysis procedures clearly. It, however, can not only be applied to any other complicate modern switch networks that have intelligent flow control but also estimate the performance of any size networks with multiple-buffered switches. To validate the proposed analysis model, the simulation is carried out on the various sizes of Fat-tree networks that uses the multiple buffered crossbar switches. Less than 2% differences between analysis and simulation results are observed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.2 no.2
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• pp.82-102
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• 2008

Packet losses tend to occur during short error bursts separated by long periods of relatively error-free transmission. There is also a significant spatial correlation in loss among the receiver nodes in a multicast session. To recover packet transmission errors at the transport layer, tree-based protocols construct a logical tree for error recovery before data transmission is started. The current tree construction scheme does not scale well because it overloads the sender node. We propose a scalable recovery tree construction scheme considering these properties. Unlike the existing tree construction schemes, our scheme distributes some tasks normally handled by the sender node to specific nodes acting as repair node distributors. It also allows receiver nodes to adaptively re-select their repair node when they experience unacceptable error recovery delay. Simulation results show that our scheme constructs the logical tree with reduced message and time overhead. Our analysis also indicates that it provides fast error recovery, since it can reduce the number of additional retransmissions from its upstream repair nodes or sender node.

• Journal of the Korea Society for Simulation
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• v.6 no.2
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• pp.45-57
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• 1997

MAC (media access control) bridge is used to interconnect separate LANs and to relay frames between the BLANs (bridged LANs). Bridge architecture consists of MAC entity, MAC relay entity and bridge protocol entity protocol entity and performs learning, filtering and forwarding functions using filtering database. In this paper, we simulate these functions of bridge and the STP (spanning tree protocol). The STP derives an active topology from an arbitrarily connected BLAN. Our simulation model assumes a BLAN consisted of three bridge forming a closed loop. In order to remove the loop, each bridge process exchanges configruation BPDU (bridge protocol data unit0 with other bridge processes connected to the bridge itself. To simulate the communication between bridges, we implement the IPC (inter-process communication) server using message queues. Our simulation results show that the assumed BLAN contains no closed loop and then there is no alternative route and no unnecessary traffic.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5A
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• pp.502-510
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• 2011

In this paper, we propose a slot scheduling algorithm for balancing power consumption in tree-based sensor networks. In this type of networks, nodes with lower depths tend to consume more energy than those with higher depths, thereby reducing the life time of the network. The proposed algorithm allocates a series of receiving slots first and then a series of sending slots. This way of slot allocation eases packet aggregation and filtering, and thus reduces traffic load on nodes near a sink. We compare the proposed algorithm and the frame-slot allocation algorithm employed in the TreeMAC by resorting to simulation. The simulation results showed that the proposed approach well achieves the balancing of power consumption.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1984.04a
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• pp.18-21
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• 1984

In this paper, the tree coding using the (M, L) multi-path search algorithm has teen investigated. A hybrid adaptation scheme which employs a block adaptation as well as a sequential dadptation is described for application in quantization and compression of speech signals. Simulation results with the gybrid adaptation scheme indicate that a relatively good speech quality can be obtained at rate about 8Kbps. All necessary parameters such as MlL and filter-order were found from simulation and these parameters turned out to be a good compromise between the complexity and overall performance.

• Proceedings of the Korea Society for Simulation Conference
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• 2000.11a
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• pp.219-225
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• 2000

본 연구에서는 이산사건 동적 시스템을 모델링하고 성능을 분석하기 위한 통합 소프트웨어를 개발하였다. 소프트웨어는 페트리네트를 기반으로 비쥬얼 C++와 비쥬얼 베이직을 이용하여 개발되었으며 윈도우즈 환경 하에서 동작하는 범용 그래픽도구를 내장하고 있다. 본 소프트웨어를 이용하면 사용자는 마우스의 드래그 앤 드롭만으로 페트리네트 모델을 작성할 수가 있으며 모델이 작성되면 수리적 분석과 시뮬레이션을 통하여 시스템의 성능분석을 자동으로 수행하여 준다. 또한 시스템의 논리적인 특성을 분석하기 위하여 coverbility tree와 reachability tree를 지원한다. 이외에도 deadlock을 탐지하고 이를 해소하는 기능과 정교한 세부 모델링이 가능하도록 다양한 활성화 함수와 분포를 지원하며 시스템의 성능척도와 관련된 다양한 통계치를 제공해준다.

• 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.

• Journal of the Korea Society for Simulation
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• v.32 no.3
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• pp.67-74
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• 2023

A semiconductor fabrication facility(FAB) is one of the most capital-intensive and large-scale manufacturing systems which operate under complex and uncertain constraints through hundreds of fabrication steps. To improve fab performance with intuitive scheduling, practitioners have used weighted-sum scheduling. Since the determination of weights in the scheduling significantly affects fab performance, they often rely on simulation-based decision making for obtaining optimal weights. However, a large-scale and high-fidelity simulation generally is time-intensive to evaluate with an exhaustive search. In this study, we investigated three sampling methods (i.e., Optimal latin hypercube sampling(OLHS), Genetic algorithm(GA), and Decision tree based sequential search(DSS)) for the optimization. Our simulation experiments demonstrate that: (1) three methods outperform greedy heuristics in performance metrics; (2) GA and DSS can be promising tools to accelerate the decision-making process.

• Journal of the Korean Institute of Landscape Architecture
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• v.27 no.4
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• pp.143-150
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• 1999

The purpose of this research is to find som ways to model tree forms more efficiently in reference with surveying structural data and handling parameters in plant Editor of AccuRender, the AutoCAD-based rendering software adopting the procedural plant modeling technique. In case of modelling a new tree, because it is efficient to modify an existing tree data as a template, we attempted to classify 81 species' data from existing plant library including conifers and deciduous tree. According to the qualitative characteristics and quantitative parameters of geometrical and branching structure, 8 types of tree form were classified with factor and cluster analysis. Some critical aspects found in the distributions of standardized scores of parameters in each type were discussed for explaining the tree forms intuitively. For adaptability of the resulted classification and typical parameters, 10 species of tree were measured and modelled, and proved to be very similar to the real structures of tree forms. CG or CAD-based plant modelling technique would be recommended not only as a presentation tool but for planting design, landscape simulation and assessment.