• MALSORI
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• no.50
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• pp.123-137
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• 2004

In this paper, we consider the implementation of connected digit recognition system using tree structured lexicon model. To implement efficiently the fixed or variable length digit recognition system, finite state network (FSN) is required. We merge the word network algorithm that implements the FSN with lexical tree search algorithm that is used for general speech recognition system for fast search and large vocabulary systems. To find the efficient modeling of digit recognition system, we investigate some performance changes when the lexical tree search is applied.

• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.3
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• pp.49-57
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• 2010

We extended a general attack tree to apply cyber attack model for network vulnerability analysis. We defined an extended cyber attack tree (E-CAT) which extends the general attack tree by associating each node of the tree with a transition of attack that could have contributed to the cyber attack. The E-CAT resolved the limitation that a general attack tree can not express complex and sophisticate attacks. Firstly, the Boolean expression can simply express attack scenario with symbols and codes. Secondary, An Attack Generation Probability is used to select attack method in an attack tree. A CONDITION-composition can express new and modified attack transition which a aeneral attack tree can not express. The E-CAT is possible to have attack's flexibility and improve attack success rate when it is applied to cyber attack model.

• The KIPS Transactions:PartC
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• v.16C no.6
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• pp.731-736
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• 2009

In wireless sensor network, many sensor nodes are distributed in the field. They communicate the sensing data each other and forward it to sink. Routing protocols, which define the delivery methods of sending data, affect to the lifetime of sensor network. This paper proposes RTAF that is a routing-tree construction algorithm of sensor nodes by a single flooding process in wireless sensor network. A routing tree is constructed by selecting a parent node using the forward-direction flooding packet and gathering children nodes using the reverse-direction flooding packet. In this process, a node with much energy becomes the parent node. And the routing tree is periodically reconstructed in order to distribute the loads of parent nodes. The proposed algorithm compared performance with Modified-LEACH using NS2 network simulation tool. The simulation result shows that the proposed algorithm constructs a routing-tree faster and reduced 40-80% in routing-tree construction packet.

• Journal of Korea Water Resources Association
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• v.54 no.1
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• pp.49-60
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• 2021

This study presents a methodology to estimate two distinct fractal dimensions of natural river basin by using fractal tree concept. To this end, an analysis is performed on fractal features of a complete drainage network which consists of all possible drainage paths within a river basin based on the growth process of fractal tree. The growth process of fractal tree would occur only within the limited drainage paths possessing stream flow features in a river basin. In the case of small river basin, the bifurcation process of network is more sensitive to the growth step of fractal tree than the meandering process of stream segment, so that various bifurcation structures could be generated in a single network. Therefore, fractal dimension of network structure for small river basin should be estimated in the form of a range not a single figure. Furthermore, the network structures with fractal tree from this study might be more useful information than stream networks from a topographic or digital map for analysis of drainage structure on small river basin.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.1
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• pp.109-117
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• 2011

It was calculated using empirical formulas for the weight of Tetrapod, which was a representative armor unit in the rubble mound breakwater in Korea. As the formulas were evaluated from a curve-fitting with the result of hydraulic test, the uncertainty of experimental error was included. Therefore, the neural network and M5' model tree were used to minimize the uncertainty and predicted the stability number of armor block. The index of agreement between the predicted and measured stability number was calculated to assess the degree of uncertainty for each model. While the neural network with the highest index of agreement have an excellent prediction capability, a significant disadvantage exists that general designers can not easily handle the method. However, although M5' model tree has a lower prediction capability than the neural network, the model tree is easily used by the designers because it has a good prediction capability compared with the existing empirical formula and can be used to propose the formulas like an empirical formula.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.6
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• pp.1424-1432
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• 2009

For the efficient management of hospital sickbeds, it is important to predict the length of stay (LoS) of appendicitis patients. This study analyzed the patient data to find factors that show high positive correlation with LoS, build LoS prediction models using neural network and decision tree models, and compare their performance. In order to increase the prediction accuracy, we applied the ensemble techniques such as bagging and boosting. Experimental results show that decision tree model which was built with less number of variables shows prediction accuracy almost equal to that of neural network model, and that bagging is better than boosting. In conclusion, since the decision tree model which provides better explanation than neural network model can well predict the LoS of appendicitis patients and can also be used to select the input variables, it is recommended that hospitals make use of the decision tree techniques more actively.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.6
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• pp.693-702
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• 2015

The objective of this study is to investigate and evaluate that a roadside tree root intrudes sewer network systems. Two approaches were performed to assess the characteristics of tree root intrusion. First, the characteristics of tree roots that had invaded sewers were directly observed by means of closed-circuit television inspection robot. Second, the intrusion proportions of tree root into rain gutters in the sampling area were investigated. As tree species of low intrusion proportions, the results indicated that Ginkgo biloba Linn. and Acer buergerianum Miq. were 1.7% and 4.3%. On the other hand, tree species of high intrusion proportions were Metasequoia glyptostroboides Hu et Cheng, Ulmus davidiana var. japonica Nakai and Zelkova serrata Makino as 22.2%, 20.4%, and 17.6% respectively. In particular, sewers and gutters around Zelkova species should be the focus of maintenance work because of the high proportion of these trees on roadsides.

• Journal of KIISE:Information Networking
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• v.31 no.2
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• pp.224-232
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• 2004

To guarantee the reliability in multicast transmission, researches providing reliability through hierarchical control tree which is independent on data channel tree are known to provide high scalability. However, the logical control tree in transport layer constructed without topology information of the corresponding network layer tree may inefficiently use the network resources because the logical control tree is not closely related to the tree topology of the network layer. A router assisted control tree mechanism presented in this paper would improve the efficiency of the link as well as it would remove the replicated data. In addition, it requires to a router a small change which examines the message type of the control tree.

• Journal of the Korea Society of Computer and Information
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• v.19 no.9
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• pp.65-73
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• 2014

Since Time synchronization is also critical in Wireless Sensor Networks (WSN) like other networks, a time synchronization protocol for WSN called IBS(Indirect-Broadcast Synchronization) has been already proposed in 2012. As IBS operates in cluster tree topology, network lifetime may be mainly shortened by cluster head node[s], which usually consumes more power than cluster member (i.e. non-cluster head) nodes. In this paper, I propose enhanced version of IBS (called EIBS) which saves overall energy and prolongs network lifetime by re-constructing partial cluster tree locally. Compared with other tree construction approaches, this tree reconstruction algorithm is not only simpler, but also more efficient in the light of overall power consumption and network lifetime.

• Proceedings of the IEEK Conference
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• 2000.11c
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• pp.59-62
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• 2000

In this paper, We propose the new interconnection network which is designed to edge numbering method using inorder traversal a Fibonacci trees and its jump sequence is Fibonacci numbers. It has a simple (shortest path)routing algorithm, diameter, node degree. It has a spaning subtree which is Fibonacci tree and it is embedded Fibonacci tree. It is compared with Hypercube. We improve diameter compared with Hypercube on interconnection network measrtes.