• Journal of Korea Multimedia Society
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• v.8 no.7
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• pp.857-868
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• 2005

Schema clustering is important as a prerequisite to the integration of XML schemas. This paper presents an efficient method for clustering XML schemas. The proposed method first computes similarities among schemas. The similarity is defined by the size of the common structure between two schemas under the assumption that the schemas with less cost to be integrated are more similar. Specifically, we extract one-to-one matchings between paths with the largest number of corresponding elements. Finally, a hierarchical clustering method is applied to the value of similarity. Experimental results with many XML schemas show that the method has peformed better compared with previous works, resulting in a Precision of $99\%$ and a rate of clustering of $93\%$ in average.

• Journal of Broadcast Engineering
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• v.11 no.2 s.31
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• pp.153-163
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• 2006

We propose a new video compression method based on MCTF(motion compensated temporal filtering) with constant quality. SPECK is an efficient image compression coding method of encoding DWT coefficients. Especially SPECK method is very efficient for coding the motion compensated residual image which usually has larger amounts of high frequency components than the natural images. And proposed multi block size hierarchical motion estimation technique is more efficient than classical block matching algorithm with fixed block size both in estimation precision and operation costs. Proposed video method based on MCTF video compression can also support multi-frame rate decoding with reasonable complexity. Simulation results showed that proposed method outperforms H.263 video compression standard.

• Proceedings of the Korean System Dynamics Society
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• 1999.08a
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• pp.105-132
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• 1999

If a system such as a port has a large boundary and complexity, and the system's substance is considered as a black box, forecast accuracy will be very low. Furthermore various components in a port exert significant influence on each other. To copy with these problem the form of structure models were introduced by using SD method. The Competitive Ports Model had several sub-systems consisting of each Unit Port models, and each Unit Port model was made by quantitative, qualitative factors and their feedback loops. The fact that all components of one port have influence on the components of the other ports should be taken into account to construct Competitive Port Models. However, with the current approach that is impossible, and in this paper, therefore, models were simplified by HFP adapted to integrate level variables of unit port models. Although many studies on modelling of port competitive situation have been conducted, both theoretical frame and methodology are still very weak. In this study, a new algorithm called ESD(Extensional System Dynamics) for the evaluation of port competition was presented, and applied to simulate port systems in northeast Asia.

• Journal of Korean Library and Information Science Society
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• v.39 no.2
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• pp.291-312
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• 2008

This study intends to make a comprehensive investigation on an application of FRBR model to KORMARC records. To the end, issues associated with FRBR implementation are analyzed, and automatic algorithms to covert bibliographic records into FRBR model are examined thoroughly. On the basis of it. this study implemented four-level hierarchical bibliographic structure of FRBR model using existing KORMARC records. 161 sample records for an experiment were selected from Korea national library. The work chosen as sample records was "Hamlet." Results suggest that considerable difficulties would be encountered in the process of FRBRizing KORMARC records.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.7
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• pp.1582-1587
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• 2005

In coagulant control of water treatment plants, rule extraction, one of datamining categories, was performed for coagulant control of a water treatment plant. Clustering methods were applied to extract control rules from data. These control rules can be used for fully automation of water treatment plants instead of operator's knowledge for plant control. To perform fuzzy clustering, there are some coefficients to be determined and these kinds of studies have been performed over decades such as clustering indices. In this study, statistical indices were taken to calculate the number of clusters. Simultaneously, seed points were found out based on hierarchical clustering. These statistical approaches give information about features of clusters, so it can reduce computing cost and increase accuracy of clustering. The proposed algorithm can play an important role in datamining and knowledge discovery.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.12
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• pp.1124-1132
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• 2011

This paper deals with smooth path generation using B-spline for fixed-wing unmanned aerial vehicles manuevering in 2D environment. Hexagonal cell representation is employed to model the 2D environment, which features increased connectivity among cells over square cell representation. Subsequently, hexagonal cell representation enables smoother path generation based on a discrete sequence of path from the path planner. In addition, we present an on-line path smoothing algorithm incorporating B-spline path templates. The path templates are computed off-line by taking into account all possible path sequences within finite horizon. During on-line implementation, the B-spline curves from the templates are stitched together repeatedly to come up with a reference trajectory for UAVs. This method is an effective way of generating smooth path with reduced on-line computation requirement, hence it can be implemented on a small low-cost autopilot that has limited computational resources.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.61.1-61.1
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• 2016

Black hole (BH) mass is a fundamental quantity to understand BH growth, galaxy evolution, and connection between them. Thus, obtaining accurate and precise BH mass estimates over cosmic time is of paramount importance. The rest-frame UV CIV ${\lambda}1549$ broad emission line is commonly used for BH mass estimates in high-redshift AGNs (i.e., $2{\leq}z{\leq}5$) when single-epoch (SE) optical spectra are available. Achieving correct and accurate calibration for CIV-based SE BH mass estimators against the most reliable reverberation-mapping based BH mass estimates is thus practically important and still useful. By performing multi-component spectral decomposition analysis to obtained high-quality HST UV spectra for the updated sample of local reverberation-mapped AGNs including new HST STIS observations, CIV emission line widths and continuum luminosities are consistently measured. Using a Bayesian hierarchical model with MCMC sampling based on Hamiltonian Monte Carlo algorithm (Stan NUTS), we provide the most consistent and accurate calibration of CIV-based BH mass estimators for the three line width characterizations, i.e., full width at half maximum (FWHM), line dispersion (${\sigma}_{line}$), and mean absolute deviation (MAD), in the extended BH mass dynamic range of log $M_{BH}/M_{\odot}=6.5-9.1$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.3
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• pp.395-402
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• 2003

The capacity of a CDMA cellular system is determined by the amount of interference, therefore the exact estimation of interference is important to evaluate the system performance. In this paper, we propose an approximated equation which calculates reverse link other cell interference in the CDMA cellular systems. The equation using Riemann-Zeta function has a property that it is useful in case of any radio propagation loss exponents. And we compare calculation results with simulation results in other to verify it's usefulness. The upper bound of system capacity calculated with the proposed approximated equation gives almost alike result with the simulation. The proposed interference bound is useful to calculate system capacity and to evaluate some algorithm in a hierarchical cellular system which must be considered various propagation exponents.

• The Transactions of the Korea Information Processing Society
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• v.3 no.5
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• pp.1198-1206
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• 1996

This paper proposes the functionality of communication network management which operates in central control station of satellite communication network, which will be constructed to DAMA-SCPC ground station using KORE ASAT. And communication network configuration components are classified with hierarchical structure in order to efficiently maintain communication network operation management, and configuration components that are classified into graphic objects and this graphic objects are visualized with tree structure which can be handled uniformally and efficiently. In addition to that, this paper proposes expression method of graphic object to implement our real time communication network management system, and the real time communication net-work management composed as client-server system. The performance of the proposed algorithm is analyzed through the computer simulation.

• Journal of IKEEE
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• v.11 no.4
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• pp.322-330
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• 2007

Recent advances in wireless networks and low-cost, low-power design have led to active research in large-scale networks of small, wireless, low power sensors and actuators, In large-scale networks, lots of timing-synchronization protocols already exist (such as NTP, GPS), In ad-hoc networks, especially wireless sensor networks, it is hard to synchronize all nodes in networks because it has no infrastructure. In addition, sensor nodes have low-power CPU (it cannot perform the complex computation), low batteries, and even they have to have active and inactive section by periods. Therefore, new approach to time synchronization is needed for wireless sensor networks, In this paper, I propose Energy-Efficient Time Synchronization (EETS) protocol providing network-wide time synchronization in wireless sensor networks, The algorithm is organized two phase, In first phase, I make a hierarchical tree with sensor nodes by broadcasting "Level Discovery" packet. In second phase, I synchronize them by exchanging time stamp packets, And I also consider send time, access time and propagation time. I have shown the performance of EETS comparing Timing-sync Protocol for Sensor Networks (TPSN) and Reference Broadcast Synchronization (RBS) about energy efficiency and time synchronization accuracy using NESLsim.