• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.574-576
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• 2021

It is necessary to introduce micro-service techniques when constructing large-scale operating systems or systems that take into account scalability. Kafka is a message queue with the pub/sub model, which has features that are well applied to distributed environments and is also suitable for microservices in that it can utilize various data sources. In this paper, we propose a data sharing method for educational video sharing services using Apache's Kafka. The proposed system builds a Kafka cluster for the educational video sharing service to share various data, and also uses a spark cluster to link with recommendation systems based on similarities in educational videos. We also present a way to share various data sources, such as files, various DBMS, etc.

• Journal of the Korea Society of Computer and Information
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• v.25 no.10
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• pp.23-34
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• 2020

In this paper, we proposes a method to automatically construct SHACL schemas for RDF knowledge graphs(KGs) generated by Direct Mapping(DM). DM and SHACL are all W3C recommendations. DM consists of rules to transform the data in an RDB into an RDF graph. SHACL is a language to describe and validate the structure of RDF graphs. The proposed method automatically translates the integrity constraints as well as the structure information in an RDB schema into SHACL. Thus, our SHACL schemas are able to check integrity instead of RDBMSs. This is a consideration to assure database consistency even when RDBs are served as virtual RDF KGs. We tested our results on 24 DM test cases, published by W3C. It was shown that they are effective in describing and validating RDF KGs.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.338-341
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• 2003

According to a long-term master plan for the implementing of MOMAF's marine environmental informatization, we have developed marine environment portal web site which consists of 7 main-menu and 39 sub-menu including various types of contents (text, image and multimedia) based on RDBMS. This portal site was opened in Oct., 2002 (http://www.meps.info). Also, for the national institutions' distributed DB which is archived and managed respectively the marine chemical data and biological data, the integrated retrieval system was developed. This system is meaningful for the making collaborative use of real data and could be applied for data mining, marine research, marine environmental GIS and making-decisions.

• Journal of KIISE:Databases
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• v.33 no.5
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• pp.551-562
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• 2006

XML query caching for XML database-backed Web applications began to be investigated recently. Despite its practical significance, efficiency of the storage schemes for cached query results has not been addressed. In this paper, we deal with the storage schemes for XML query cache. A fundamental problem that needs to be considered in designing an efficient storage structure for XML query cache is that there exist performance tradeoffs between the two major types of operations on a cached query result. The two are (1) retrieving the whole of it to return the query result and (2) updating just a small portion of it for its incremental refresh against the updates done to its source. We propose eight different storage schemes for XML query cache, which are categorized into three groups: (1) the schemes based on the plain text file, (2) the schemes based on the persistent DOM (PDOM) file, and (3) a scheme employing an RDBMS. We implemented all of them, and compared their performance with each other. We also compared our proposal with a storage scheme based on a current state-of-the-art XML storage scheme, showing that ours is more efficient.

• Journal of Korea Multimedia Society
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• v.10 no.7
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• pp.807-816
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• 2007

Since W3C proposed XML in 1996, XML documents have been widely spreaded in many internet documents. Because of this, needs for research related with XML is increasing. Especially, it is being well performed to study XML management system for storage, retrieval, and management with XML Documents. Among these studies, XRel is a representative study for XML management and has been become a comparative study. In this study, we suggest XML documents management system based on Relational DataBase Management System. This system is stored not all possible path expressions such as XRel, but filtered path expression which has text value or attribute value. And by giving each node Node Expression Identifier, we try to match given Node Expression Identifier. Finally, to prove efficiency of the suggested technique, this paper shows the result of experiment that compares XPath query processing performance between suggested study and existing technique, XRel.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.11
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• pp.2067-2075
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• 2017

Lately big data processing is considered as an emerging issue. As a huge amount of data is generated, data processing capability is getting important. In processing big data, both Hadoop distributed file system and unstructured date processing-based NoSQL data store are getting a lot of attention. However, there still exists problems and inconvenience to use NoSQL. In case of low volume data, MapReduce of NoSQL normally consumes unnecessary processing time and requires relatively much more data retrieval time than RDBMS. In order to address the NoSQL problem, in this paper, an interworking scheme between NoSQL and the conventional RDBMS is proposed. The developed auto-mapping scheme enables to choose an appropriate database (NoSQL or RDBMS) depending on the amount of data, which results in fast search time. The experimental results for a specific data set shows that the database interworking scheme reduces data searching time by 35% at the maximum.

• The Journal of Society for e-Business Studies
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• v.14 no.1
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• pp.57-79
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• 2009

As the Web-based e-Business prevails, the volume of XML data on the Web is getting larger than ever. Although much research has been done on decomposing and storing XML data in RDB, which is now the most popular storage for XML, and on processing XML queries through their SQL counterparts, little attention was paid to how to alleviate the burden of storing massive volume of XML data. In this paper, we propose a hybrid method of storing XML data in RDB, whereby the unit of storage could be an XML subtree as well as an XML node. The part of XML data whose nodes were separately stored could be reformed into an XML subtree for storing when it gets rarely queried or less valuable for reference as time goes by. With this method, we designed and implemented a hybrid XML storage and query processing system, comparing it with the conventional system where an XML node is the only unit of storage. Through experiments, we compared storage efficiency and query processing performance, validating the effectiveness of our proposed system.

• Journal of KIISE:Databases
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• v.31 no.2
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• pp.183-194
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• 2004

As XML is a do facto standard for a data exchange language, there have been several researches on efficient processing XML queries. The most important thing to consider when processing XML queries is how efficiently we can process path expressions in queries. Some previous works make results by performing a sequence of join operations on all records corresponding to labels in the path expression. Others works check the existence of paths in the query using an RDBMS's string comparison operator and make results by extracting the records corresponding to the paths. In this paper we suggested a new query planning algorithm based on path containment relationships and two join operators supporting the planning algorithm. The join operators use only the records related to the paths in a query as input data, scan them only once, and generate result data using a pipelining mechanism. By analysis and experiments, we confirmed that our techniques(a new query planning algorithm and two join operators) achieved significantly higher performance than other previous works.

• Journal of Digital Contents Society
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• v.6 no.2
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• pp.107-112
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• 2005

We need a research for representing and processing of multimedia data in database because of increasing the importance and utilization of the data owing to development of internet technology. RDBMS supports only the storing-structure to store multimedia, but the support for data type, representation and query of multimedia is insufficient. To cope with this problem, ISO/IEC standardized SQL multimedia(SQL/MM) for multimedia data. However, ORDBMS supports SQL/MM, but RDBMS does not support it. Therfore, this theis proposes a query interpreter to support SQL/MM in MS-SQL 2000 as one of RDBMS and introduces a image retrieval application using it. The quary interpreter supports the function to convert SQL/MM into SQL, and additionally the function of the image duplication check. The image processing application using a query interpreter can easily be integrated and operated with traditional RDBMS-based system.

• The KIPS Transactions:PartD
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• v.15D no.4
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• pp.549-556
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• 2008

Web-based Enterprise Intranet System is developed Object-oriented programming language and data management is constructed using RDBMS. Between Object-oriented programming language and RDBMS bring about "Object-Relational Impedance Mismatch" due to heterogeneous paradigm. To solve this kinds of problems commonly use the ORM Framework that it is converting data between incompatible type systems in databases and object-oriented programming languages, uses complex mapping metadata. It causes difficult to develop and maintain because of inflexible in changes. This paper proposed persistence framework that solve the existing complexity of ORM framework and has more flexible in evolution of database table. This persistence framework is unnecessary meta information that connecting with entity of database table and the objects, it offers users convenience of maintenance and it allows far more flexible and affordable systems to be built because of automatically code generation. The result of testing based on the proposed persistence framework with Hibernate, iBATIS, It is similar response time with iBATIS and it has more about three times faster than Hibernate. But iBATIS has problems of mass data processing.