• Journal of Korea Multimedia Society
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• v.9 no.9
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• pp.1118-1130
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• 2006

Existed pattern analysis algorithms in data streams environment have researched performance improvement and effective memory usage. But when new data streams come, existed pattern analysis algorithms have to analyze patterns again and have to generate pattern tree again. This approach needs many calculations in real situation that needs real time pattern analysis. This paper proposes a method that continuously analyzes patterns of incoming data streams in real time. This method analyzes patterns fast, and thereafter obtains real time patterns by updating previously analyzed patterns. The incoming data streams are divided into several sequences based on time based window. Informations of the sequences are inputted into a hash table. When the number of the sequences are over predefined bound, patterns are analyzed from the hash table. The patterns form a pattern tree, and later created new patterns update the pattern tree. In this way, real time patterns are always maintained in the pattern tree. During pattern analysis, suffixes of both new pattern and existed pattern in the tree can be same. Then a pointer is created from the new pattern to the existed pattern. This method reduce calculation time during duplicated pattern analysis. And old patterns in the tree are deleted easily by FIFO method. The advantage of our algorithm is proved by performance comparison with existed method, MILE, in a condition that pattern is changed continuously. And we look around performance variation by changing several variable in the algorithm.

• Journal of Korea Multimedia Society
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• v.10 no.8
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• pp.1052-1059
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• 2007

Network security system used in the large scale network composes individual security system which protects only own domain. Problems of individual security system are not to protect the backbone network and to be hard to cope with in real-time. In this paper we proposed a security system which includes security function at the router, and the access point, which exist at the backbone network, to solve the problems. This security system sends the alert messages to an integrated security management system after detecting intrusions. The integrated security management system releases confrontation plan to each suity system. Thus the systematic and immediate confrontation is possible. We analyzed function verification and efficiency by using the security system and the integrated security management system suggested in this paper. We confirmed this integrated security management system has a possibility of a systematic and immediate confrontation.

• The Transactions of the Korea Information Processing Society
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• v.4 no.6
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• pp.1495-1507
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• 1997

Among a number of approaches to text compression, adaptive dictionary schemes based on a sliding window have been very frequently used due to their high performance. The LZ77 algorithm is the most efficient algorithm which implements such adaptive schemes for the practical use of text compression. This paperpresents a VLSI architecture designed for processing the LZ77 algorithm in parallel. Compared with the other VLSI architectures developed so far, the proposed architecture provides the more viable solution to high performance with regard to its throughput, efficient implementation of the VLSI systolic arrays, and hardware scalability. Indeed, without being affected by the size of the sliding window, our system has the complexity of O(N) for both the compression and decompression and also requires small wafer area, where N is the size of the input text.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.2090-2101
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• 2015

We propose a robust tracking method that combines the merits of ACM(active contour model) and the color-based PF(particle filter), effectively. In the proposed method, PF and ACM track the color distribution and the contour of the target, respectively, and Decision part merges the estimate results from the two trackers to determine the position and scale of the target and to update the target model. By controlling the internal energy of ACM based on the estimate of the position and scale from PF tracker, we can prevent the snake pointers from falsely converging to the background clutters. We appled the proposed method to track the head of person in video and have conducted computer experiments to analyze the errors of the estimated position and scale.

• Journal of the Korean Data and Information Science Society
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• v.28 no.5
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• pp.1109-1123
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• 2017

This paper examines there is any differences among determinants of cash holdings and marginal value of cash depending on the life-cycle of firm. To accomplish these objective, we collect financial and market data of KRX listing firms for a period of 2001-2013. We present evidence of significant effect of life-cycle on the cash holdings determinants and marginal value of cash. Specially, the effect of investment opportunity related variable are varies through life-cycle. The results also suggest that marginal values of cash in the introduction stage and exit stage is higher than those in other stages. Overall, this means that the motive of cash holdings in Korean firms is weak. and shareholders place different value on a firm's cash holdings depending on the life-cycle.

• Journal of Digital Contents Society
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• v.14 no.3
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• pp.283-290
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• 2013

The current centralized mobility control protocols such as proxy mobile IPv6 (PMIPv6) are dependent on a central mobility anchor to process all control/data traffic. However, such centralized mobility control protocols have some drawbacks such as traffic concentration into the core network and serious service degradation in case of the failure of such a centralized mobility anchor, etc. In this paper, therefore, in order to alleviate these drawbacks, we propose a PMIPv6-based distributed mobility control scheme considering a user's movement locality. Performance evaluation results demonstrate that the proposed scheme has apparent potentials to alleviate serious drawbacks of S-PMIP, which is a closely-related distributed mobility control scheme, as well as PMIPv6, while reducing the total mobility control cost.

• Journal of Korea Multimedia Society
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• v.23 no.4
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• pp.566-573
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• 2020

Computers are the most common tool when using the Internet and utilizing a mouse to select and execute objects. Eye tracking technology is welcomed as an alternative technology to help control computers for users who cannot use their hands due to their disabilities. However, the pointer execution method of the existing eye tracking technique causes many malfunctions. Therefore, in this paper, we developed a gaze tracking interface that combines voice commands to solve the malfunction problem when the upper limb disabled uses the existing gaze tracking technology to execute computer menus and objects. Usability verification was conducted through comparative experiments regarding the improvements of the malfunction. The upper limb disabled who are hand-impaired use eye tracking technology to move the pointer and utilize the voice commands, such as, "okay" while browsing the computer screen for instant clicks. As a result of the comparative experiments on the reduction of the malfunction of pointer execution with the existing gaze interfaces, we verified that our system, Eye-Voice, reduced the malfunction rate of pointer execution and is effective for the upper limb disabled to use.

• Journal of KIISE:Software and Applications
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• v.31 no.10
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• pp.1304-1319
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• 2004

We can significantly reduce the cost o# program testing by automating the process of test data generation. Test data generation usually concerns identifying input values on which a selected path is executed. Although lots of research has been done so far, there still remains a lot of issues to be addressed. One of the issues is the shape problem. The shape problem refers to the problem of figuring out a shape of the input data structure required to cause the traversal of a given path. In this paper, we introduce a new method for the shape problem. The method converts the selected path into static single assignment (SSA) form without pointer dereferences. This allows us to consider each statement in the selected path as a constraint involving equality or inequality. We solve the constraints to get a solution which will be represented in terms of the points-to relations for each input variable. Simple, but illustrative examples are given to explain the proposed method.

• The Journal of the Korea Contents Association
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• v.5 no.2
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• pp.187-197
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• 2005

In this paper, we propose an extended TB-tree, called ETB-tree, which can improve the performance of an existing TB-tree proposed for indexing the trajectories of moving objects in Location-Based Service(LBS). The proposed ETB-tree directly accesses the preceding node by maintaining a direct table, called D-Table which contains the page number in disk and memory pointers pointing the leaf node with the first and last lines segment of moving objects. It can improve the insertion performance by quick searching the preceding node of a moving object and retrieval performance owing to accessing directly the corresponding trajectories In disk for the trajectory-based query. In addition, the ETB-tree provides consistency of a tree by reflecting a newly inserted line segment to the tree both in memory and disk. The experimental results show that the proposed indexing technique gains better performance than other traditional ones with respect to the insertion and retrieval of a trajectory query.

• The Journal of the Korea Contents Association
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• v.10 no.12
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• pp.70-76
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• 2010

This paper Extended ELZW(EBCDIC Lempel Ziv Welch) algorithm uses 2 byte prefix field for pointer of a table and 1 byte suffix field for repeat counter. where, a prefix field uses a pointer(index) of compression table and a suffix field uses a counter of overlapping or recursion text data in compression table. To increase compression ratio, after construction of compression table, table data are properly packed as different bit string in accordance with a alphabet, Hangeul, and pointer respectively. Therefore, proposed ELZW algorithm is superior to 1byte LZW algorithm as 5.22 percent and superior to 2byte LZW algorithm as 8.96 percent.