• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.1B
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• pp.48-57
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• 2008

Wireless sensor networks are composed of a lot of sensor nodes and they are used to monitor environments. Since many studies on wireless sensor networks have considered a stationary sink node, they cannot provide fully ubiquitous applications based on a mobile sink node. In those applications, routing paths for a mobile sink node should be updated while a sink node moves in order to deliver sensor data without data loss. In this paper, we propose a method to continuously update routing paths for a mobile sink node which can be extended on hierarchical multi-hop routing protocols in wireless sensor networks. The efficiency of the proposed scheme has been validated through comparing existing method using a location based routing protocol by extensive computer simulation.

• The KIPS Transactions:PartB
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• v.12B no.7 s.103
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• pp.737-744
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• 2005

In this paper, we propose a three-level color clustering algerian for the binarization of text regions extracted from natural scene images. The proposed algorithm consists of three phases of color segmentation. First, the ordinary images in which the texts are well separated from the background, are binarized. Then, in the second phase, the input image is passed through a high pass filter to deal with those affected by natural or artificial light. Finally, the image Is passed through a low pass filter to deal with the texture in texts and/or background. We have shown that the proposed algorithm is more effective used gray-information binarization algorithm. To evaluate the effectiveness of the proposed algorithm we use a commercial OCR software ARMI 6.0 to observe the recognition accuracies on the binarized images. The experimental results on word and character recognition show that the proposed approach is more accurate than conventional methods by over $35\%$.

• Journal of Navigation and Port Research
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• v.27 no.4
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• pp.465-469
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• 2003

It has well known that MUSIC and ESPRIT algorithms estimate angle of arrival(AOA) with high resolution by eigenvalue decomposition of the covariance matrix which were obtained from the array antennas, However, the disadvantage of MUSIC and ESPRIT is that they are computationally ineffective, and then they are difficult to implement in real time. the other problem of MUSIC and ESPRIT is to require calibrated antennas with uniform features, and are sensitive ti the manufacturing fault and other physical uncertainties. To overcome these disadvantages, several method using neural model have been study. For multiple signals, those methods require huge training data prior to AOA estimation. This paper proposes the algorithm for AOA estimation by interconnected Hopfield neural model. Computer simulations show the validity of the proposed algorithm. It follows that the proposed method yields better AOA estimates than MUSIC. Moreover, out method does not require huge training procedure and only assigns interconnected coefficients to the neural network prior to AOA estimation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.886-889
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• 2010

Power consumption measurement in sensor network is difficult to proceed by survey in real field. Thus, through simulation, the power consumption is estimated and replacement time of nodes are decided. A simulation tool simulates various facts such as power consumption, packet transmission traffic, network topology and etc. In this paper, it suggests sensor node power model to simulate power consumption which has large importance among simulation facts in sensor network. This model omits calculating expressions that the data originally surveyed can substitute with, according to power consumption property of each functions in sensor node in order to minimize calculations in simulation. In this case accuracy of power consumption estimation will be reduced, but can simulate it faster due to reduced calculation. Suggested model is fitted to analyze power consumption difference between two or more sensor network algorithms with rapid simulation speed rather than accurate simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.3
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• pp.425-433
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• 2018

In this paper, we propose a super-resolution reconstruction algorithm for plenoptic images based on the reliability of disparity. The subperture image generated by the Flanoptic camera image is used for disparity estimation and reconstruction of super-resolution image based on TV_L1 algorithm. In particular, the proposed image reconstruction method is effective in the boundary region where disparity may be relatively inaccurate. The determination of reliability of disparity vector is based on the upper, lower, left and right positional relationship of the sub-aperture image. In our method, the unreliable vectors are excluded in reconstruction. The performance of the proposed method was evaluated by comparing to a bicubic interpolation method, a conventional disparity based method and dictionary based method. The experimental results show that the proposed method provides the best performance in terms of PSNR(Peak Signal to noise ratio), SSIM(Structural Similarity).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.10
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• pp.1405-1411
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• 2018

This paper designs access control system for MS-word(Microsoft-word) document system. The system designed in this paper uses the document-related information by analyzing the MS-word document structure. It is designed to block access to users who can not access the modified information by partially modifying MS-word document information. This makes it impossible to read documents other than those who have access to the MS-word document. This allows you to control access to the MS-word document. A user with access to the MS-word document will be able to retrieve the modified information back to the original information so that the document can be read normally. In this paper, we design and implement experiments. In the experiment, we performed document access if MS-word document information was modified. Experimental results show that the MS-word access control system operates normally.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.8
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• pp.1894-1902
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• 2009

As the spread of LBS(Location Based Service), MDT(Mobile Data Terminal) and PDA (Personal Digital Assistant) services using mobile terminals, various systems are under development to to manage the performance of these services. This paper describes a mobile performance management system which is implemented to test the performance of mobility between the user and the terminal or between the terminal and the mobile server automatically in the mobile-user field. The system has four modules: scenario management module, MDT monitoring, LBS monitoring, and PDA monitoring. The scenario management module manages the performance by monitoring all modules. The LBS monitoring module monitors LBS call attempt stage, call connecting stage, and LBS test for established connection. Thus, the LBS monitoring module manages the performance for every stage of the call. The MDT monitoring module monitors the performance according to the input command and the PDA monitoring module monitors according to the input from the set up and the execution menu.

• Journal of KIISE:Information Networking
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• v.36 no.3
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• pp.222-230
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• 2009

A sensor network is an important element of the ubiquitous and it consists of sensor fields that contain sensor nodes and sink nodes that collect data from sensor nodes. Since each sensor node has limited resources, one of the important issues covered in the past sensor network studies has been maximizing the usage of limited energy to extend network lifetime. However, most studies have only considered fixed sink nodes, which created various problems for cases with multiple mobile sink nodes. Accordingly, while maintaining routes to mobile sink nodes, this study aims to deploy the hybrid communication mode that combines single and multi-hop modes for intra-cluster and inter-cluster transmission to resolve the problem of failed data transmission to mobile sink nodes caused by disconnected routes. Furthermore, a 2-level hierarchical routing protocol was used to reduce the number of sensor nodes participating in data transmission, and cross-shape trajectory forwarding was employed in packet transmission to provide an efficient data dissemination method.

• Journal of KIISE:Information Networking
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• v.30 no.5
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• pp.621-630
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• 2003

In this paper, we implemented SIP protocol that supports IPv6 and differentiated call processing scheme for NGN(Next Regeneration Network). In NGN, SIP processes call signaling among various application services. A softswitch and SIP server must give priority to sensitive services such as Fax, network management and home networking that require a fast call setup time. Also, the support of IPv6 is needed under consideration of All-IP. We proposed differentiated call processing scheme. The differentiated call processing scheme supports differentiated call processing as priority of service class on call processing in SW server We defined three service classes and use the Flow Label field of the IPv6 header for setting service class. Through the performance analysis, we proved that it improves throughput for call message with the high priority. The result of performance analysis demonstrates that differentiated call processing scheme gives better performance for the service requiring a fast session establishment in NGN.

• The KIPS Transactions:PartD
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• v.16D no.2
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• pp.201-212
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• 2009

There are various methods to trace output in software development to verify the consistency and completeness of requirements. Existing studies do present the trace meta-model or automated tools, but fail to list specifically traced output or traced items. Also, in regards to trace tables, which contain traced items, existing studies don‘t consider the whole software development process but merely its sub-process. Given this, the present study suggests an extended requirements tracetable that tracks output from the inception of the project through the architectural design phase to the application delivery, following up on the researcher’s previous study on a tracetable that considered only a sub-process of the whole development process. In addition, in order to address the problem of the tracking process becoming complicated with increased tracefields due to an extended trace table, the researcher suggests a method for normalizing a requirements tracetable that can integrate and separate by development process phase. Apply it to theH system development project of a D company, and this study caseverified application possibility of study, confirmed an effect of a chase to easily find out an error of requirements. Improve precision of a traceto verify consistency of requirements and completeness through this study, and will minimize failure of a software development.