• Journal of the Semiconductor & Display Technology
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• v.3 no.4
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• pp.13-17
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• 2004

As the usage of wireless LAN becomes common in working environment, the number of database systems that support both wired and wireless users increases rapidly. The characteristics of wireless LAN that its speed is slow relatively comparing to wired network and the users in its environment connects to different communication points as they moves creates another challenge to be resolved in database systems. In the environment of hybrid communication systems, wired and wireless for voluminous data amount and a number of users, the two layer architecture of the conventional client-server database systems has limitation in the system performance. This is due to that server is the only point of data service in client-server database systems. In this paper, we discuss a new extended database system architecture that data services are distributed among servers and clients based on user database access patterns in order to improve system performance. We analyze the expected system performance by using simulation technique and prove the practical utilization of the system by demonstrating experimental results.

• The Journal of Society for e-Business Studies
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• v.4 no.1
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• pp.1-19
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• 1999

Workflow management system provides automation of job processes by maintaining shareability on information about various job process schedules and persons related to those schedules. Existing workflow management systems use file or database to store the information generated in those systems. However, file or database system could manage only non-complicated information for the workflow but not the information resources of an enterprise which is complicated and of various formats. Therefore, we need a data management system that could control those information resources. This system should manage the data which are distributed at several places geographically. Information Repository could meet those requirements. Information Repository may integrate, store and manage information resources requested by application systems. We have an international standard for the information repository, Information Resources Dictionary System(IRDS). The IRDS, however, does not support distributed environment. In this paper, we design and implement an information repository based on IRDS that may be operated in distributed environment. We verify that this information repository is more effective and is more effective than any other file or database system.

• The Journal of Information Systems
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• v.14 no.3
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• pp.17-22
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• 2005

Location management is very important in location-based services to provide services to the mobile users like banking, city guides and many more. Ubiquitous and mobile devices are the source of data in location management and its significant operations are update and search method. Some studies to improve these were presented by using optimal sequential paging, location area scheme and hierarchical database scheme. In addition, not all location services have the same access methods on data and it lead to difficulties of providing services. A proposed location management of multi-agent architecture is presented in this study. It shows the coordination of the agents on the distributed database of location-based services. The proposal focuses on the location management of the mobile object presented in a hierarchical search and update. Also, it uses a nearest neighbor technique for efficient search method of mobile objects.

• Asia pacific journal of information systems
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• v.5 no.2
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• pp.131-142
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• 1995

In distributed database systems materialized views are useful to solve many problems caused by data replication. This paper deals with the problem of updating materialized views incluing join operations. We use a differential update which uses logs that record the change of base tables in certain periods. This method avoids locking of the base tables so that it makes the system more efficient. We update materialized views periodically to save the updating cost envolved. A screen test is applied to differential files to eliminate tuples that are irrelevant to any of the views being updated. Using these methods, a detailed procedure is addressed to refresh materialized views. Then we show that our update procedure performs better than a semijoin approach.

• Journal of Korea Multimedia Society
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• v.12 no.2
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• pp.178-190
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• 2009

XML is recommended by W3C(World Wide Web) and widely accepted as a standard markup language for expression and sharing data. Recently, increasing the use and the amount of XML documents, there is required that easy methods for accessing XML documents at anytime and anywhere, therefore, the distributed XML repository systems is developed. For this, distributed XML repository systems is necessary to research catalog management schemes. In this paper, we design distributed XML database model considering CPU costs, I/O costs, concurrency control, two-phase commits a protocol, queuing delay and so on. And we implement a simulator in order to execute performance evaluation centralized catalog method, fully replicated catalog method, and partitioned catalog method using reasonably setting up environments.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10a
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• pp.11-12
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• 2007

• Proceedings of the Korea Database Society Conference
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• 1994.09a
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• pp.49-69
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• 1994

A client/server system has become the computing architecture for the business organization which seeks competitive edges. Technically, a client/server system places application processing close to the user and thus increases performance. This paper's two primary goals are (i) to present a performance model for client/server database systems and (ii) to demonstrate analytically the effectiveness of client/server computing in comparison with other computing architectures via an illustrative example. The model is most likely to be used as a practical performance guide for client/server computing.

• Journal of Korea Game Society
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• v.1 no.1
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• pp.31-36
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• 2001

Generally, the internet online game systems are divided into two parts, clients and servers. The clients provide a connection with game server to each user and communicate between them. And, the server controls all clients by the game rules fairly and manages database systems to maintain the user information. In this paper, we propose a configuration method for internet online game servers using distributed scheme. To apply this method, we divide game server into three sub-level parts again. First part of game server is login server to establish the connection between communication server and clients. Second part is communication server to connect between clients and main game server during playing the game. And last part is DBMS that performs database independently. Our proposed scheme suggests that the game server operates very stable because of decreasing of processing load by distributed scheme. So, our proposed server configuration applies to similar online game easily.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.9
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• pp.1867-1879
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• 1997

DREAM-S is a distributed main-memory database system for the real-time processing of shared operational datra in ATM switching systems. DREAM-S has a client-server architecture in which only the server has the diskstorage, and provides the T-Tree index structure for efficient accesses to the data. We propose a recovery technique for the T-Tree index structre in DREAM-S. Although main-memory database system offer efficient access performance, the database int he main-memory may be broken when system failure such as database transaction failure or power failure occurs. Therfore, a recovery technique that recovers the database (including index structures) is essential for fault tolerant ATM switching systems. Proposed recovery technique relieves the bottleneck of the server processors disk operations by maintaining the T-Tree index structure only in the main-memory. In addition, fast recovery is guaranteed even in large number of client systems since the T-Tree index structure(s) in each system can be recovered cncurrently.

• International Journal of Computer Science & Network Security
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• v.23 no.5
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• pp.128-134
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• 2023

The widespread usage of blockchain technology in cryptocurrencies has led to the adoption of the blockchain concept in data storage management systems for secure and effective data storage and management. Several innovative studies have proposed solutions that integrate blockchain with distributed databases. In this article, we review current blockchain databases, then focus on two well-known blockchain databases-BigchainDB and FalconDB-to illustrate their architecture and design aspects in more detail. BigchainDB is a distributed database that integrates blockchain properties to enhance immutability and decentralization as well as a high transaction rate, low latency, and accurate queries. Its architecture consists of three layers: the transaction layer, consensus layer, and data model layer. FalconDB, on the other hand, is a shared database that allows multiple clients to collaborate on the database securely and efficiently, even if they have limited resources. It has two layers: the authentication layer and the consensus layer, which are used with client requests and results. Finally, a comparison is made between the two blockchain databases, revealing that they share some characteristics such as immutability, low latency, permission, horizontal scalability, decentralization, and the same consensus protocol. However, they vary in terms of database type, concurrency mechanism, replication model, cost, and the usage of smart contracts.