• Journal of KIISE:Software and Applications
• /
• v.32 no.4
• /
• pp.247-257
• /
• 2005

Generally, the network topology design problem is characterized as a kind of NP-hard combinatorial optimization problem, which is difficult to solve with the classical method because it has exponentially increasing complexity with the augmented network size. In this paper, we propose the efficient approach with two phase that is comprised of evolutionary computation approach based on Prufer number(PN), which can efficiently represent the spanning tree, and a heuristic method considering 2-connectivity, to solve the highly reliable network topology design problem minimizing the construction cost subject to network reliability: firstly, to find the spanning tree, genetic algorithm that is the most widely known type of evolutionary computation approach, is used; secondly, a heuristic method is employed, in order to search the optimal network topology based on the spanning tree obtained in the first Phase, considering 2-connectivity. Lastly, the performance of our approach is provided from the results of numerical examples.

• Korean Journal of Remote Sensing
• /
• v.23 no.6
• /
• pp.529-536
• /
• 2007

As the Imperious surface is an important index for the estimation of urbanization and environmental change, the increase of impervious surfaces causes meteorological and hydrological changes like urban climate change, urban flood discharge increasing, urban flood frequency increasing, and urban flood modelling during the rainy season. In this study, the estimation of impervious surfaces is performed by using Landsat-7 ETM+ image in An-sung area. The construction of sampling data and checking data is used by IKONOS image. It transform to a tasselled cap and NDVI through the reflexibility rate of Landsat ETM+ image and analyze various variables that influence on impervious surface. Finally, the impervious surfaces map is accomplished by regression tree algorithm.

• Proceedings of the KSME Conference
• /
• 2000.04b
• /
• pp.655-660
• /
• 2000

Animation technique from the PIV database is particularly emphasized to give macroscopic and quantitative description of complex flow fields. This paper shows animation construction and application example for the post-processing of PIV data. As examples, first case is a pitching airfoil immersed in tree surface water circulating tunnel. Second case is a wake of a model-ship. Third case of PIV data is a large scale surface flow field. Obtained images are processed in time sequence by PIV exclusive routines where an efficient and reliable cross correlation algorithm is included for vector identification. All. animation Jobs are implemented completely on single personal computer environment. Compressed digital images are obtained initially by Motion-JPEG board and various An files are finally obtained through graphic processes.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.6A
• /
• pp.600-610
• /
• 2010

In this paper, a multicast mechanism is proposed for intermittently disconnected networks where the nodes move forward in formation or within a limited area. The proposed scheme extends the well-known tree-based multicast routing mechanism called MAODV by modifying the tree construction and data delivery scheme. Especially, an algorithm is introduced which determines the flooding hop count k estimating the degree of the movement of children in the tree. The performance evaluation was done by the simulation and the proposed scheme was compared with MAODV and two multicast routing schemes for DTN (Disruption Tolerant Network) including the Epidemic routing and ST-multicast. The evaluation results show that our scheme improves the original MAODV from the aspect of tree reconstruction events and message delivery ratio. Compared with the Epidemic routing scheme, our scheme achieves 85% message delivery ratio with less than 50% message delivery overhead.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.15 no.6
• /
• pp.71-79
• /
• 2016

Evaluation of the walkability of the urban pedestrian network requires construction of a pedestrian network model that reflects Space Syntax Theory. Space Syntax Theory deduces an integration value through which materials for evaluation of the pedestrian network's connectivity can be produced; and can aid in illustrating the ease of walkability through the model's calculation of pedestrian indices such as movability, comfort, and safety. But the representation of space syntax theory in the pedestrian network requires that turn delay be added by means of a network-type construction method. While tree-based Dial Algorithm proposed for the logit-based probability walkability distribution model may be effective for link-based pedestrian volume distribution, it requires further network expansion to reflect turn delays. In this research, Vine-based Dial Algorithm is executed in order to obtain a measure reflecting the integration value for Space Syntax Theory. The Vine-based Dial Algorithm of two adjacent links, which forms the minimum unit of the Vine network, has the advantage of encompassing turn delay, and thus eliminates the need for network expansion. Usage of the model to evaluation of complicated pedestrian spheres such as urban roads is left to further research. Especially the progression of the proposed method is deduced through case study.

• The Journal of the Acoustical Society of Korea
• /
• v.13 no.3
• /
• pp.63-70
• /
• 1994

In this Paper, we propose a new codeword tying algorithm based on a tree structured classfier. The proposed algorithm which can be viewed as a kind of soft decision using statistical properties between codewords and states has an advantage of fast construction, and guarantees a unique optimal solution. Also, it can easily be applied to any speech recognition system based on discrete hidden Markov model (HMM). Experimental results on speaker-independent isolated word recognition show error reduction of $6\%$ for the codebook of size 256 and $9\%$ for 512 size and also HMM parameter reduction of about $20\%$.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.6
• /
• pp.2922-2945
• /
• 2018

Achieving efficient authentication is a crucial issue for stream data commonly seen in content delivery, peer-to-peer, and multicast/broadcast networks. Stream authentication mechanisms need to be operated efficiently at both sender-side and receiver-side at the same time because of the properties of stream data such as real-time and delay-sensitivity. Until now, many stream authentication mechanisms have been proposed, but they are not efficient enough to be used in stream applications where the efficiency for sender and receiver sides are required simultaneously since most of them could achieve one of either sender-side and receiver-side efficiency. In this paper, we propose an efficient stream authentication mechanism, so called TIM, by integrating Trapdoor Hash Function and Merkle Hash Tree. Our construction can support efficient streaming data processing at both sender-side and receiver-side at the same time differently from previously proposed other schemes. Through theoretical and experimental analysis, we show that TIM can provide enhanced performance at both sender and receiver sides compared with existing mechanisms. Furthermore, TIM provides an important feature for streaming authentication, the resilience against transmission loss, since each data block can be verified with authentication information contained in itself.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.22 no.5
• /
• pp.575-589
• /
• 2020

In recent years, Shield TBM construction has been continuously increasing in domestic tunnels. The main excavation tool in the shield TBM construction is a disc cutter which naturally wears during the excavation process and significantly degrades the excavation efficiency. Therefore, it is important to know the appropriate time of the disc cutter replacement. In this study, it is proposed a predictive model that can determine yes/no of disc cutter replacement using machine learning algorithm. To do this, the shield TBM machine data which is highly correlated to the disc cutter wears and the disc cutter replacement from the shield TBM field which is already constructed are used as the input data in the model. Also, the algorithms used in the study were the support vector machine, k-nearest neighbor algorithm, and decision tree algorithm are all classification methods used in machine learning. In order to construct an optimal predictive model and to evaluate the performance of the model, the classification performance evaluation index was compared and analyzed.

• ETRI Journal
• /
• v.44 no.4
• /
• pp.573-587
• /
• 2022

The agricultural sector is completely different from other sectors since it completely relies on various natural and climatic factors. Climate changes have many effects, including lack of annual rainfall and pests, heat waves, changes in sea level, and global ozone/atmospheric CO₂ fluctuation, on land and agriculture in similar ways. Climate change also affects the environment. Based on these factors, farmers chose their crops to increase productivity in their fields. Many existing agricultural ontologies are either domain-specific or have been created with minimal vocabulary and no proper evaluation framework has been implemented. A new agricultural ontology focused on subdomains is designed to assist farmers using Jaccard relative extractor (JRE) and Naïve Bayes algorithm. The JRE is used to find the similarity between two sentences and words in the agricultural documents and the relationship between two terms is identified via the Naïve Bayes algorithm. In the proposed method, the preprocessing of data is carried out through natural language processing techniques and the tags whose dimensions are reduced are subjected to rule-based formal concept analysis and mapping. The subdomain ontologies of weather, pest, and soil are built separately, and the overall agricultural ontology are built around them. The gold standard for the lexical layer is used to evaluate the proposed technique, and its performance is analyzed by comparing it with different state-of-the-art systems. Precision, recall, F-measure, Matthews correlation coefficient, receiver operating characteristic curve area, and precision-recall curve area are the performance metrics used to analyze the performance. The proposed methodology gives a precision score of 94.40% when compared with the decision tree(83.94%) and K-nearest neighbor algorithm(86.89%) for agricultural ontology construction.

• Journal of KIISE:Information Networking
• /
• v.35 no.5
• /
• pp.402-408
• /
• 2008

This paper considers the problem of minimizing network-wide broadcast latency in multi-rate wireless mesh networks where a node can dynamically adjust its link layer transmission rates to its neighbors. We propose a broadcast algorithm that complements existing broadcast construct algorithm which chooses a multicast node randomly when each candidate node has same metric. We consider the currently accumulated broadcast latency from source node to the each candidate node so far to choose the next broadcast node. The proposed broadcast algorithm for minimizing latency in a multi-rate mesh networks which exploit wireless advantage and the multi-rate nature of the network. Simulation based on current 802.11 parameters shows that proposed MinLink_WCDS algorithm improves overall latency than the previous existing broadcast algorithm.