• Journal of The Korean Association of Information Education
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• v.5 no.1
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• pp.159-167
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• 2001

According to the development of the educational information business, many schools have been changing. For example, school networks and education networks have been constructed, the teaching-learning methods have been diversified, and information has been shared. But the information are not being controlled and shared effectively in schools and classrooms. The purpose of this study is to research school networks increasing efficiency highly with low expenses, to design Linux-based class management database on the basis of analyzing the teacher's class management, and to develop this database which can help teachers manage classes effectively.

• The Journal of Information Systems
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• v.6 no.1
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• pp.159-180
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• 1997

Database sharing system(DBSS) refers to a system for high performance transaction processing. In DBSS, the processing nodes are locally coupled via a high speed network and share a common database at the disk level. Each node has a local memory, a separate copy of operating system, and a DBMS. To reduce the number of disk accesses, the node caches database pages in its local memory buffer. However, since multiple nodes may be simultaneously cached a page, cache consistency must be ensured so that every node can always access the latest version of pages. In this paper, we propose efficient buffer invalidation schemes in DBSS, where the database is logically partitioned using primary copy authority to reduce locking overhead. The proposed schemes can improve performance by reducing the disk access overhead and the message overhead due to maintaining cache consistency. Furthermore, they can show good performance when database workloads are varied dynamically.

• Journal of KIISE:Databases
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• v.32 no.2
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• pp.142-150
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• 2005

A shared disks (SD) cluster couples multiple computing nodes, and every node shares a common database at the disk level. A great deal of research indicates that the SD cluster is suitable to high performance transaction processing, but the aggregation of SD cluster with real-time processing has not been investigated at all. A real-time transaction has not only ACID properties of traditional transactions but also time constraints. By adopting cluster technology, the real-time services will be highly available and can exploit inter-node parallelism. In this paper, we first develop an experiment model of an SD-based real-time database system (SD-RTDBS). Then we investigate the feasibility of real-time transaction processing in the SD cluster using the experiment model. We also evaluate the cross effect of real-time transaction processing algorithms and SD cluster algorithms under a wide variety of database workloads.

• Journal of the Korea Society of Computer and Information
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• v.11 no.6 s.44
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• pp.289-298
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• 2006

Many researches are going on with regard to issues and problems related to mobile database systems, which are caused by the weak connectivity of wireless networks, the mobility and the portability of mobile clients. Mobile computing satisfies user's demands for convenience and performance to use information at any time and in any place, but it has many problems to be solved in the aspect of data management. The purpose of our study is to design Mobile Continuous Query Processing System(MCQPS) to solve problems related to database hoarding, the maintenance of shared data consistency and the optimization of logging, which are caused by the weak connectivity and disconnection of wireless networks inherent in mobile database systems under mobile client server environments. We proved the superiority of the proposed MCQPS by comparing its performance to the C I S(Client-Intercept-Slaver) model. In Addition, we experiment on proposed index structure and methodology in various methods.

• Proceedings of the Korea Contents Association Conference
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• 2005.05a
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• pp.315-319
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• 2005

In this paper, we present a Petri Net (PN) model for reliability analysis of fault-tolerant database system models that consists of components one shared memory, bus, processors and database (disk). Each component can be failed and repaired individually. The system is operational as long as database and one of component is operational. We develop Stochastic Reward Net (SRN) Model for reliability analysis of database system. SRN is potential to define various reward functions. and can be easily used to obtain performance measures. The modeling techniques using variable cardinality, enabling function, timed transition priority in SRN are shown.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.1346-1351
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• 2009

In this paper we propose a framework for an Object Relational IFC Server (OR-IFC Server). Enormous amounts of information are generated in each project. Today, many BIM systems are developed by various CAD software vendors. Industry Foundation Classes (IFC) developed by International Alliance for Interoperability (IAI) is an open standard data model for exchanging data between the various BIM tools. The IFC provides a foundation for exchanging and sharing of information directly between software applications and define a shared building project model. The IFC model server is a database management system that can keep track of transactions, modifications, and deletions. It plays a role as an information hub for storing and sharing information between various parties involved in construction projects. Users can communicate with each other via the internet and utilize functions implemented in the model server such as partial data import/export, file merge, version control, etc. IFC model servers using relational database systems have been developed. However, they suffered from slow performance and long transaction time due to a complex mapping process between the IFC structure and a relational-database structure because the IFC model schema is defined in the EXPRESS language which is object-favored language. In order to simplify the mapping process, we developed a set of rules to map the IFC model to an object-relational database (ORDB). Once the database has been configured, only those pieces of information that are required for a specific information-exchange scenario are extracted using the pre-defined information delivery manual (IDM). Therefore, file sizes will be reduced when exchanging data, meaning that files can now be effectively exchanged and shared. In this study, the framework of the IFC server using ORDB and IDM and the method to develop it will be examined.

• Journal of Information Management
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• v.23 no.2
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• pp.40-56
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• 1992

The inhouse database can be used as an effective tool for managing inhouse/corporaterelated informations, which efficiently support business activities as they are shared by all the inhouse members. The inhouse database construction processes can be classified into a concept design, various kinds of DB format designs, abstracting/indexing, and DB operation/maintenance. This article presents a method of systematizing the concept design elements such as information flow support system, usable resources, and so on.

• Journal of Electrical Engineering and information Science
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• v.2 no.5
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• pp.89-99
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• 1997

The application for real-time database systems must satisfy timing constraints. Typically the timing constraints are expressed in the form of deadlines which are represented by priorities to e used by schedulers. In any real-time applications, since the system maintains sensitive information to be shared by multiple users with different levels of security clearance, security is another important requirement. As more advanced database systems are being used in applications that need to support timeliness while managing sensitive information, protocols that satisfy both requirements need to be developed. In this appear, we proposed a new priority-driven secure multiversion locking (PSMVL) protocol for real-time secure database systems. The schedules produced by PSMVL are proven to e one-copy serializable. We have also shown tat the protocol eliminates covert channels and priority inversions. The details of the protocol, including the compatibility matrix and the version selection algorithms are presented. the results of the performance comparisons of our protocol with other protocols are described.

• The Journal of Information Technology
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• v.9 no.4
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• pp.35-47
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• 2006

Many researches are going on with regard to issues and problems related to mobile database systems, which are caused by the weak connectivity of wireless networks, the mobility and the portability of mobile clients. Mobile computing satisfies user's demands for convenience and performance to use information at any time and in any place, but it has many problems to be solved in the aspect of data management. The purpose of our study is to Implement Real-Time Mobile Query Processing System(MQPS) to solve problems related to database hoarding, the maintenance of shared dataconsistency and the optimization of logging, which are caused by the weak connectivity and disconnection of wireless networks inherent in mobile database systems under mobile client server environments. In addition, we proved the superiority of the proposed MQPS by comparing its performance to the C I S(Client-Intercept-Srever) model.

• Journal of the Korean Operations Research and Management Science Society
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• v.24 no.4
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• pp.157-170
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• 1999

The web-based groupware systems hold many possibilities for system developers and users. Especially, web-based group collaborative systems are emerging as enterprise-wide information systems. Since data in group collaborative systems are apt to be shared among multiple concurrent users and modified simutaneously by them, the web-based group collaborative systems must support synchronous collaboration in order to provide users with synchronized and consistent views of shared data. However, current web technologies have limitations in supporting this, largely because the existing Hypertext Transfer Protocol(HTTP) is unidirectional and does not allow web servers to send messages to their web browsers without first receiving requests from them. This paper proposes an active web server that can overcome such limitations and facilitate synchronous collaboration in web-based group collaborative systems. To accomplish such goals, the active web server manages dependency relationships beween shared data and web browsers referencing them and actively propagates changing details of the shared data to all web browsers referencing them. And, this paper examines usefulness and effectiveness of the active web server to apply it to the ball-bearing design example of concurrent engineering design systems. The prototype system of the active web server is developed on a commercial Object-oriented Database Management System(0DBMS) called OBJECTSTERE using the C++ programming language.