• Journal of KIISE:Databases
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• v.30 no.3
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• pp.225-236
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• 2003

MOLAP systems store data in a multidimensional away called a 'cube' and access them using way indexes. When a cube is placed into disk, it can be Partitioned into a set of chunks of the same side length. Such a cube storage scheme is called the chunk-based MOLAP cube storage scheme. It gives data clustering effect so that all the dimensions are guaranteed to get a fair chance in terms of the query processing speed. In order to achieve high space utilization, sparse chunks are further compressed. Due to data compression, the relative position of chunks cannot be obtained in constant time without using indexes. In this paper, we propose a bitmap index for chunk-based MOLAP cubes. The index can be constructed along with the corresponding cube generation. The relative position of chunks is retained in the index so that chunk retrieval can be done in constant time. We placed in an index block as many chunks as possible so that the number of index searches is minimized for OLAP operations such as range queries. We showed the proposed index is efficient by comparing it with multidimensional indexes such as UB-tree and grid file in terms of time and space.

• Journal of KIISE:Software and Applications
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• v.30 no.7_8
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• pp.610-617
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• 2003

Similarity matching in video database is of growing importance in many new applications such as video clustering and digital video libraries. In order to provide efficient access to relevant data in large databases, there have been many research efforts in video indexing with diverse spatial and temporal features. however, most of the previous works relied on sequential matching methods or memory-based inverted file techniques, thus making them unsuitable for a large volume of video databases. In order to resolve this problem, this paper proposes an effective and scalable indexing technique using a trie, originally proposed for string matching, as an index structure. For building an index, we convert each frame into a symbol sequence using a window order heuristic and build a disk-resident trie from a set of symbol sequences. For query processing, we perform a depth-first search on the trie and execute a temporal segmentation. To verify the superiority of our approach, we perform several experiments with real and synthetic data sets. The results reveal that our approach consistently outperforms the sequential scan method, and the performance gain is maintained even with a large volume of video databases.

• Journal of Navigation and Port Research
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• v.30 no.3 s.109
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• pp.189-195
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• 2006

Sea operation monitoring system is a system for the automatic ship operation that is used on the variety sea operations such as laying optical cables on the sea between the countries, laying cables on the seabed for a remote island, laying pipelines for the natural gas, and so forth. This system processes data which obtained through setting up environment and input from several sensors, and display GPS information with ENC data. And this system processes not only data of route file about sea operation, but also realtime information from PDA of client wirelessly connected with AP on wireless LAN. In addition, this system can improve efficiency of the operation as a result of enabling free movement within valid range. This paper design and implementation monitoring system from above appropriate to the embedded system, and improve competitive power of ship through prevention of a ship accident, to keep minimizing operation loads and support both the automatic ship operation and the safety voyage.

• Journal of the Korean Society for information Management
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• v.18 no.3
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• pp.29-40
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• 2001

In this paper, we suggest a query optimization algorithm to select the optimal processing method of an extended boolean query on inverted files. There can be a lot of methods for processing an extended boolean query according to the processing sequence oh the keywords con tamed in the query, In this sense, the problem of optimizing an extended boolean query it essentially that of optimizing the keyword sequence in the query. In this paper, we show that the problem is basically analogous to the problem of finding the optimal join order in database query optimization, and apply the ideas in the area to the problem solving. We establish the cost model for processing an extended boolean query and develop an algorithm to filled the optimal keyword-processing sequence based on the concept of keyword rank using the keyword selectivity and the access costs of inverted file. We prove that the method selected by the optimization algorithm is really optimum, and show, through experiments, that the optimal method is superior to the others in performance We believe that the suggested optimization algorithm will contribute to the significant enhancement of the information retrieval performance.

• Journal of Korea Multimedia Society
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• v.12 no.10
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• pp.1397-1406
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• 2009

This paper propose the "Digital Format Registry(DFR)" to solve the problem related digital objects preservation system in the Korean Industry. Digital format registry is a kind of database that saves syntax and meaning informations of a digital file format and for giving help to make preserve in long-term even technical environment of a specific application has been changing. The role of the Technical Information Registry has been developed in this research and development is maintaining a technical information that is the foundation to maintain the long-term preservation and access to a digital objects. The function that can extract text information from a digital document object is implemented in DFR as a basic function at the first time in the world. This function make information consumers search a information that is needed easily and conveniently and can be used for development more effective records management system with retrieving the Key(index).

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.6
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• pp.75-84
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• 2014

In order to solve the problems such as overload, single point of failure, non-optimized data path, and network scalability in conventional central mobility management protocols, distributed mobility management schemes have been continually studied in and around the IETF. In this paper, a network-based partially-distributed mobility management mechanism, pDMMv6, is suggested and the performance comparison with traditional protocols such as PMIPv6 and MIPv6 is made through simulation under the various user traffic environment. The simulation results include UDP packet delivery ratio, end-to-end packet delay, binding delay for registration signaling, CPU utilization in each node, and response delays in several server-client TCP applications such as web browsing, e-mail, telnet remote login, FTP file up/down-load, and database access.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.315-320
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• 2009

Since flash memory can not be overwritten on updating data, new data are updated in new area and old data should be invalidated and erased for garbage collection. With develop of flash memory technology, capacity of flash memory is rapidly increasing. It increases rapidly execution time of CPU to search an entire flash memory of large capacity when choosing the block to erase in garbage collection. To solve the problem that is increasing execution time of CPU, flash memory is partitioned into several groups, the block to erase in garbage collection is searched within the corresponding group. In workload of access locality, we enhanced wear-leveling within group by allocating hot data to hot group and cold data to cold group respectively and enhanced wear-leveling among groups by exchanging periodically hot group and cold group.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1418-1425
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• 2009

This paper proposes a novel FTL (Flash Translation Layer) algorithm based on sector-level mapping to reduce the number of total erase operations in flash memory accesses. The proposed algorithm can reduce the number of erase operations by utilizing the sector-level mapping table when writing data at flash memory. Sector-level mapping technique reduces flash memory access time and extendsthe life time of the flash memory. In the algorithm, wear-leveling is implemented by selecting victim blocks having the minimal number of erase operations, when empty spaces for write are not available. To evaluate the performance of the proposed FTL algorithm, experiments were performed on several applications, such as MP3 players, MPEG players, web browsers and document editors. The proposed algorithm reduces the number of erase operations by 72.4% and 61.9%, when compared with well-known BAST and FAST algorithms, respectively.

• Journal of the Korea Society of Computer and Information
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• v.9 no.4 s.32
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• pp.5-12
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• 2004

The data transformation between XML and Relation Database is made through the Principle of mapping bewtween them. There are two ways to access SQL Server, one is to assign SQL query to URL and the other is to use template file. MS-SQL server takes advantage of OpenXML function to transform the results of executing SQL query into XML documents. That is, OpenXML first makes node tree and then transforms row set data of XML documents into XML data of relation type. In order to insert XML data into database data. data is extracted from parsing XML documents using sp_xml_preparedocument procedure, and then the document structure is mapped into tree structure and stored in a table of database. Consequently, Data transformation between XML and Relation Database is made through mapping bewtween them. This article proposes the principle of mapping between XML and Relation Database and then shows the implementation of transformation between them so that it introduces the possibilty of bringing the extension and efficiency of data and various effects.

• Journal of the Korea Society of Computer and Information
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• v.25 no.11
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• pp.51-58
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• 2020

Most of the students in computer-related departments work on projects, and it is essential to use a database for project execution. To use such a database, it is necessary to install a Database Management System. However, it takes several minutes (hours) to install a DBMS, and some DBMS require a difficult installation process. Therefore, in order to solve this problem, this study proposed a system that can easily install DBMS using Docker. Docker is an open source project that automates the deployment of Linux applications into software containers. Docker Container is wrapped in a complete file system that includes everything necessary for the execution of software, and includes code, runtime, system tools, system libraries, and anything that is installed on the server. This guarantees that they will always run the same regardless of the environment in which they are running. After creating a database using this proposed system, you can check the database access information on the web and check the server status in minutes. As a result of of implementing this proposed system and applying it to the projects of 10 teams, the installation time was reduced by 94.5% for Maria DBMS and 98.3% for Oracle DBMS than individual installation, confirming improved efficiency.