• The Korean Journal of Applied Statistics
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• v.29 no.2
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• pp.345-354
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• 2016

Inhomogeneous Poisson process models are widely applied to landslide data to understand how environmental variables systematically influence the risk of landslides. However, those models cannot successfully explain the clustering phenomenon of landslide locations. In order to overcome this limitation, we propose to use a Cauchy cluster process model and show how it improves the goodness of fit to the landslide data in terms of K-function. In addition, a numerical study is performed to select the optimal estimation method for the Cauchy cluster process.

• The Journal of the Acoustical Society of Korea
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• v.26 no.5
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• pp.199-206
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• 2007

In this paper we propose a new clustering algorithm that performs clustering the feature vectors for the speaker identification. Unlike typical clustering approaches, the proposed method performs the clustering without the initial guesses of locations of the cluster centers and a priori information about the number of clusters. Cluster centers are obtained incrementally by adding one cluster center at a time through the boundary subtractive clustering algorithm. The number of clusters is obtained from investigating the mutual relationship between clusters. The experimental results for artificial datum and TIMIT DB show the effectiveness of the proposed algorithm as compared with the conventional methods.

• Journal of the Ergonomics Society of Korea
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• v.34 no.3
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• pp.247-264
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• 2015

Objective: The purpose of this study is to determine the priority of information presentation and the effective menu type to be placed in the center of a gauge cluster display for commercial trucks and to present a set of ergonomic designs for the gauge cluster display. Background: An effective ergonomic design is specifically needed for the development of the gauge cluster display for the commercial trucks, because more diverse and heavier information is delivered to truck drivers, compared to the information to passenger car drivers. Method: First, all the information that must be shown on the commercial truck display was collected. Then, the severity, frequency of use, and display design parameters were evaluated for those information by commercial truck drivers. Next, an analysis on the information attributes and the heuristic evaluation utilizing the display design principles were carried out. According to the results, a design alternative of the main screen to be displayed was constructed by priority. A comparative analysis between the alternative and existing main screens was also conducted to see the efficacy of the designs. Lastly, we conducted an experiment for the selection of menu type. The experiment was conducted using the driving simulator with an eye-tracking device. The independent variables were four types of the menu reflecting the commercial truck characteristics such as grid type, icon type, list type, and flow type. We measured preference, total execution time, the total duration of fixation on the gauge cluster area, and the total number of fixation on the gauge cluster area as dependent variables. Results: Four types of driver convenience information and six types of driver assistance information were selected as the information to be placed primarily on the main screen of the gauge cluster. The Grid type was the most effective among the menu types. Conclusion: In this study, the information that appears on the main screen of the display, the division of the display and the design of the menu type for commercial truck drivers were suggested. Application: This study is expected to be utilized as guidelines on the ergonomic design of a gauge cluster display for commercial trucks.

• International journal of advanced smart convergence
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• v.6 no.1
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• pp.50-56
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• 2017

Wireless sensor nodes have limited energy, so it is important to optimize energy consumption to preserve network lifetime. Various protocols have been proposed for this purpose. LEACH protocol and SEP are the representative protocols. These protocols become less effective as the Sensor Field becomes wider. To improve this, MR-SEP and L-SEP were proposed. These protocols increase the energy efficiency by dividing the Sensor Field into layers and reducing the transmission distance. However, when dividing a layer, there are cases where it is divided inefficiently, and a node within a certain range from a Base Station has a better transmission efficiency than a direct transmission method using a cluster method. In this paper, we propose a Single-hop layer for L-SEP to improve inefficient layer division and near node transmission efficiency. When the larger the Sensor Field, the better the performance of the proposed method by up to 87%. The larger the sensor field, the more efficient the proposed method is over the conventional method. That is, the proposed method is suitable for the wide Sensor Field.

• Journal of Korea Multimedia Society
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• v.4 no.6
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• pp.543-553
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• 2001

In this paper, we proposed management strategy of medical image data in order to solve the problem in traditional medical images migration method. As management strategy of medical image data we proposed EAT(Expanded Average Transaction time) data migration method and data storing method based on temporal interrelation. In EAT data migration strategy, we define the dividing criterion which distinguish entity versions to be stored in each storage and also define entity versions to be stored in each storage. We defined degree of overlap and degree of difference for any two entity versions, and integrated those values and described method which place entity versions to storage. In order to compare the number of cluster references when we change rate of temporal queries, the number of cluster references of proposed method is smaller than that of traditional method.

• Journal of Internet Computing and Services
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• v.11 no.1
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• pp.59-69
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• 2010

With the growing number of web services, there arise issues of finding suitable services. But, the traditional keyword search method is insufficient for two reasons: (1) this does not capture the underlying semantics of web services. (2) this does not suffice for accurately specifying users' information needs. In order to overcome limitations of this keyword search method, we propose a novel syntactic analysis and ontology learning method. The syntactic analysis method gives us a breadth of coverage for common terms, while the ontology learning method gives a depth of coverage by providing relationships. By combining these two methods, we hope to improve both the recall and the precision. We describe an experimental study on a collection of 508 web services that shows the high recall and precision of our method.

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.11a
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• pp.1-1
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• 1994

;The electronic state calculations for various types of ceramic materials have beell performed by the use of $DV-X\;{\alpha}$ cluster method. The molecular orbital levels and wave functions for model clusters have been computed to study the electronic properties ami chemical bonding of the ceramics. For ${\beta}-sialon(Si_{6-z}Al_zO_zN_{8-z})$ which is a high temperature structural material based on ${\beta}-Si_3N_4$, we have made model cluster calculations to estimate the strength of chemical bonding between atoms by the Mulliken population analysis. It is found that the covalent bonding between Si and N atoms is very strong in pure ${\beta}-Si_3N_4$, but the covalency around solute atom is considerably weakened when Si atom is substituted by AI. This tendency is enhanced by an additional substitution of oxygen atom for N. The result calculated can well explain the experimental data of changes in mechanical properties such as the reductions of Young's modulus and Vickers hardness with increment of z-value in ${\beta}-sialon$. Various model clusters for transition metal oxides which show many interesting physical and chemical properties have also been calculated. High-valent perovskite-type iron oxides EMFe0_3E(M=Ca and Sr) possess very interesting magnetic and chemical properties. In these oxides, iron exists as $Fe^{4+}$ state, but the experimental measurement of Mossba~er effect suggests that disproportionation $2Fe^{4+}=Fe^{3+}+Fe^{5+}$ takes place for $CaFe0_3$ at low temperatures. The model cluster calculations for these compounds indicated the existence of considerably strong covalent bonding of Fe-O. The calculations of hyperfine interaction at iron neucleus show very good agreement with the experimental Mossbauer measurements. The result calculated also implies that the disproportionation reaction is strongly possible by assuming the quenching of breathing phonon mode at low temperatures.tures.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5487-5495
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• 2012

The important issue that applies security key are secure rekeying, processing time and cost reduction. Because of sensor node's limited energy, energy consumption for rekeying affects lifetime of network. Thus it is necessary a secure and efficient security key management method. In this paper, I propose an energy efficient group-based cluster key management (EEGCK) in the large scale sensor networks. EEGCK uses five security key for efficient key management and different polynomial degree using security fitness function of sector, cluster and group is applied for rekeying and security processing. Through both analysis and simulation, I also show that proposed EEGCK is better than previous security management method at point of network energy efficiency.

• Journal of Digital Convergence
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• v.10 no.9
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• pp.363-368
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• 2012

The Cluster-based routing protocol is consumed the energy consumption efficiently, but there are many isolated nodes while clustering, so these are impeding energy efficiency. Hop-by-hop based routing protocol is suitable large-scaled network or dynamic environment. However, with the periodic flooding signal and rapid energy loss of near sink nodes, the network life time become shorter. In this paper, We propose the hybrid routing protocol that combine the cluster based routing method for energy efficiency of nodes and hop-by-hop method for re-joining the isolated nodes and load balance of nodes in the near cluster using fibonacci sequence. Based on the analysis, it is proved that the hybrid routing protocol provided higher energy efficiency and less the isolated nodes than previous methods.

• The KIPS Transactions:PartD
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• v.9D no.5
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• pp.779-788
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• 2002

There are many technically difficult issues in searching multimedia data such as image, video and audio because they are massive and more complex than simple text-based data. As a method of searching multimedia data, a similarity retrieval has been studied to retrieve automatically basic features of multimedia data and to make a search among data with retrieved features because exact match is not adaptable to a matrix of features of multimedia. In this paper, data clustering and its indexing are proposed as a speedy similarity-retrieval method of multimedia data. This approach clusters similar images on adjacent disk cylinders and then builds Indexes to access the clusters. To minimize the search cost, the hashing is adapted to index cluster. In addition, to reduce I/O time, the proposed searching takes just one I/O to look up the location of the cluster containing similar object and one sequential file I/O to read in this cluster. The proposed schema solves the problem of multi-dimension by using clustering and its indexing and has higher search efficiency than the content-based image retrieval that uses only clustering or indexing structure.