• Journal of KIISE:Databases
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• v.36 no.5
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• pp.352-365
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• 2009

Recently, data access control policies have not been applied for authorized or unauthorized persons properly and information leakage incidents have occurred due to database security vulnerabilities. In the traditional database access control methods, administrators grant permissions for accessing database objects to users. However, these methods couldn't be applied for diverse access control policies to the database. In addition, another database security method which uses data encryption is difficult to utilize data indexing. Thus, this paper proposes an enhanced database access control system via a packet analysis method between client and database server in network to apply diverse security policies. The proposed security system can be applied the applications with access control policies related to specific factors such as date, time, SQL string, the number of result data and etc. And it also assures integrity via a public key certificate and MAC (Message Authentication Code) to prevent modification of user information and query sentences.

• Journal of Korea Multimedia Society
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• v.11 no.1
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• pp.1-12
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• 2008

Database encryption is one of the important mechanisms for prohibiting internal malicious users and outside hackers from utilizing data. Frequent occurrences of encryption and decryption cause degradation of database performance so that many factors should be considered in implementing encryption system. In this paper, we propose an architecture of database encryption system and data encryption module. In addition we suggest extended SQL in order to manage data encryption and decryption. In implementing database encryption system, we adopt ARIA encryption algorithm which is proved to be the most fast one among Korea standardized encryption algorithm. We use an single key for each database in encrypting data rather than using several keys in order to improve performance. Research over performance evaluation of database encryption system is rare up to now. Based on our implemented system, we provide performance evaluation results over various H/W platforms and compare performance differences between plain text and encrypted data.

• International Journal of Internet, Broadcasting and Communication
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• v.10 no.2
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• pp.31-38
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• 2018

As the use of open source databases grows, so does need to evaluate, the performance of search queries for these databases. This paper compares the search query performance of SQL-based open source databases with commercial databases through experiments. The targets are MySql, MariaDB, and MS-SQL Server. In this study, the execution time of various types of search queries are measured. Also, search query performance was experimented according to change of index and number of tuples. Experimental results show that SQL-based open source databases have the potential to replace commercial databases when indexes are used and the number of tuples is not very large.

• Proceedings of the Korean Society of Computer Information Conference
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• 2015.07a
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• pp.147-148
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• 2015

대학의 컴퓨터 관련 학과에서 데이터베이스에 대한 SQL(DML)을 학생들에게 숙지시키기 위한 시험(정기 시험, 퀴즈)은 필수이며, 이에 대한 채점을 수작업을 하고 있어 교수들에게 채점의 부담으로 작용하고 있다. 본 논문은 이런 부담을 덜기 위한 SQL 채점 자동화 시스템을 개발함으로써 학생들에게 채점의 부담 없이 시험을 통해 충분한 시험을 실시하도록 하는 시스템을 개발하였다. 대학에서 SQL은 SELECT, UPDATE, INSERT, DELETE 4개의 데이터 조작어로 구분되며, 기본적인 구문의 시험이 대부분이다, 이에 대한 채점 구문분석을 위한 파싱트리(parsing tree)을 만들어 자동 채점 시스템을 구현하였다.

• The KIPS Transactions:PartD
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• v.9D no.5
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• pp.789-800
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• 2002

XML is a standard format of web data and is currently used as a prevailing language for exchanging data. Most of the commercial data are stored in a relational database. It is quite important to convert these conventionally stored data into those for exchange and use them in data exchange, or to get the query results effectively by utilizing XQL on XML data which are store in a relational database. Thus, it is absolutely required to have a proper query processing mechanism for XML data and to maintain many XML data properly. Up to now, many cases of researches on the storage and retrieval of XML data have been carried out and under study. But, effective retrieval and storage system for path queries like XQL has yet to be contrived. Thus, in this paper, a schema to store XML data is designed, in which DFS-Numbegering method is used to store data effectively. And an effective path query processing method is also designed and implemented, in which a traditional relational database engine is used. That is, XQL is converted into SQL with a XQL processor if a user makes query XQL in a system. A database system executes SQL, and a XML generator uses a generated record and makes a XML document.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.12
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• pp.487-496
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• 2017

In MySQL InnoDB, there are two ways of storing data. One is to create a separate tablespace for each table and store it separately. Another is to store all table and index information in a single system tablespace. You can use this information to recover deleted data from the record. However, in most of the current database forensic studies, the former is actively researched and its structure is analyzed, whereas the latter is not enough to be used for forensics. Both approaches must be analyzed in terms of database forensics because their storage structures are different from each other. In this paper, we propose a method for recovering deleted records in a method of storing records in IBDATA file, which is a single system tablespace. First, we analyze the IBDATA file to reveal its structure. And introduce delete record recovery algorithm which extended to an unallocated page area which was not considered in the past. In addition, we show that the recovery rate is improved up to 68% compared with the existing method through verification using real data by implementing the algorithm as a tool.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.2
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• pp.223-232
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• 2017

Previous research on data recovery in Microsoft SQL Server has focused on restoring data based on in the transaction log that might have deleted records exist. However, there was a limit that was not applicable if the related transaction log did not exist or the physical database file was not connected to Server. Since the suspect in the crime scene may delete the data records using a different deletion statements besides "delete", we need to check the remaining data and a recovery possibility of the deleted record. In this paper, we examined the changes "Page Allocation information" of the table, "Unallocation deleted data", "Row Offset Array" in the page according to "delete", "truncate" and "drop" events. Finally it confirmed the possibility of data recovery and availability of management tools in Microsoft SQL Server digital forensic investigation.

• 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.

• Journal of KIISE:Databases
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• v.29 no.3
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• pp.207-216
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• 2002

Nowadays, we can easily access a remote database as well as a local database with HTML forms. Although implementing a database application with HTML forms is much simpler than implementing it with a proprietary graphical user Interface system, HTML forms and CGI programs still must be coded. We implemented a software tool that automatically generates the SQL statements that create a database for an application, the forms that are used as a user interface, and the Java servlets that retrieve the data requested through the forms. The database tables to be treated and the forms to be generated are determined by the class diagram for the application. Our software tool, which we call WebSiteGen, thus simplifies the implementation of a Web-based database application.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.108-110
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• 2019

A Database is a collection of data that does not have redundancy, and it is essential to easily use and share information in an information society where the amount of information is increasing. A typical structure of a Database is a relational database and a tree-structure Database. This research studies the programming language MUMPS, which is a tree structure database. This language constructs the database by storing arrays in a dynamic or B-Tree format. Unlike SQL, which must be used in languages such as Java and C #, MUMPS supports language and database independently and can manage data, so the data porting rate is high. In fact, in U.S. hospitals, the MUMPS-based platform has a high market share.