• Journal of KIISE:Computing Practices and Letters
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• v.6 no.2
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• pp.113-119
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• 2000

In this paper, we design and implement a query processor of real-time main memory database systems, which reflect the characteristics of main memory database systems and satisfy timing constraints. The proposed query processor manages real-time data that has timing constraint by exploiting meta database. It supports CLI in order to make application programs. It also supports extended CLI and stored CLI. The former can be expressed the Information on real-time transaction. The latter is designed to support frequently processed transaction. The proposed query processor is implemented as query processor of real-time database management systems. We Present performance evaluation results that illustrate ratio of transaction, which satisfy deadline are increased by the query processing ability of system and the efficient management of real-time data.

• The Transactions of the Korea Information Processing Society
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• v.5 no.6
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• pp.1418-1430
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• 1998

Temporal databases support an efficient historical management by means of valid time and transaction time. Valid time stands for the time when a data happens in the real world. And transaction time stands for the time when a data is stored in the database, Temporal Query Processing System(TQPS) should be extended so as tc process the temporal operations for the historical informations in the user query as well as the conventional relational operations. In this paper, the extended temporal query processing systems which is based on the previous temporal query processing system for TQuel(Temporal Query Language) consists of the temporal syntax analyzer, temporal semantic analyzer, temporal code generator, and temporal interpreter is to be described, The algorithm for additional functions such as transaction time management, temporal aggregates, temporal views, temporal joins and the heuristic optimization functions and their example how to be processed is shown.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.3
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• pp.247-253
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• 2004

This paper mainly deals with a transaction model for the reliability guarantee in a Web-Based Real-Time Reservation Service System. We suggest the Web-Based Global Transaction Model which binds up each transaction currently divided by a function into one transaction and deals with one transaction. Also, we propose a Fail-Check Process in order to deal with the exceptions to be happened in a transaction process. And the simulation shows us that the model which we suggest is feasible and possible through the transaction processing procedure.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.8
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• pp.895-904
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• 1999

• Journal of KIISE:Databases
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• v.29 no.6
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• pp.464-476
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• 2002

Main-memory database systems which reside entire databases in main memory are suitable for high-performance real-time transaction processing. If two-phase locking(2PL) as concurrency control protocol is used for the transactions accessing main-memory databases, however, the possibility of lock conflict will be low but lock operations become relatively big overhead in total transaction processing time. In this paper, We designed a real-time static locking(RT-SL) protocol which minimizes lock operation overhead and reflects the priority of transactions and we implemented it on a main-memory real-time database system, Mr.RT. We also evaluate and compare its performance with the existing real-time locking protocols based on 2PL such as 2PL-PI and 2PL-HP. The extensive experiments reveal that our RT-SL outperforms the existing ones in most cases.

• The Journal of Society for e-Business Studies
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• v.14 no.4
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• pp.119-131
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• 2009

During a decade, e-Commerce environments supporting real-time transaction processing have been getting larger. In telecommunication and financial environments, research and building for main memory database systems have been doing to support real-time transaction processing. A research on indexing for fast transaction support focuses on reducing cache misses or reducing memory access latency when cache misses happen. In the paper, we propose a prefetch method for tree index structures to reduce memory access latency. We present a prefetch-efficient pCST-tree and show superiority of the proposed tree by experiments.

• The Transactions of the Korea Information Processing Society
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• v.3 no.6
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• pp.1418-1432
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• 1996

In addition t improved availability, replication of data can enhance performance of distributed real-time transaction processing system by allowing transactions initiated at multiple node to be processed concurrently. To satisfy both the consistency and real-time constraints, it is necessary to integrate concurrency control and atomic commitment protocols with time-driven scheduling methods. blocking caused by existing concurrency control protocols is incompatible with time-driven scheduling because they cannot schedule transactions to meet given deadlines. To maintain consistency of replicated data and to provide a high degree of schedulability and predictability , the proposed time-driven scheduling methods integrate optimistic concurrency control protocols that minimize the duration of blocking and produce the serialization by reflecting the priority transactions. The atomicity of transactions is maintained to ensure successful commitment in distributed environment. Specific time-driven scheduling techniqueare discussed, together with an analysis of the performance of this scheduling.

• Journal of Information Processing Systems
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• v.1 no.1 s.1
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• pp.9-13
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• 2005

Computer security has become a critical issue with the rapid development of business and other transaction systems over the Internet. The application of artificial intelligence, machine learning and data mining techniques to intrusion detection systems has been increasing recently. But most research is focused on improving the classification performance of a classifier. Selecting important features from input data leads to simplification of the problem, and faster and more accurate detection rates. Thus selecting important features is an important issue in intrusion detection. Another issue in intrusion detection is that most of the intrusion detection systems are performed by off-line and it is not a suitable method for a real-time intrusion detection system. In this paper, we develop the real-time intrusion detection system, which combines an on-line feature extraction method with the Least Squares Support Vector Machine classifier. Applying the proposed system to KDD CUP 99 data, experimental results show that it has a remarkable feature extraction and classification performance compared to existing off-line intrusion detection systems.

• The Transactions of the Korea Information Processing Society
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• v.3 no.4
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• pp.803-816
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• 1996

It is possible to prevent deadlock if the priority which is conventionally given to transactions is endowed to data items and the transactions with the highest priority among transactions accessing the data item is allowed to proceed. Based on this observation, we proposed a Data-Priority Based Locking Protocol(DPLP) and evaluated its performance against known locking protocols in Real Time Database Management System(RTDBMS). Transaction inter-arrival time(IAT) was varied to determine success ratio, average-lateness, confict ratio and restart ratio, In these simulations we verified that the proposed DPLP performs better than the other protocols.

• The Transactions of the Korea Information Processing Society
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• v.5 no.6
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• pp.1377-1389
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• 1998

Firm real time transactions on firm real-time database systems arc discarded when they miss their deadlines. as there is no value to completing them after they miss their deadlines. Several approaches that exploit the semantics of firm deadlines to improve the performance of firm real-time database systems have been proposed in the literature. They are based Oil locking or optimistic concurrency controL The performance comparisons of the two approaches differ with svstems load. In this paper. we develop a novel policy termed stop/resume deferred restart policy, and a concurrency control algorithm based on the policy (temled Altcmativc Version Concurrency Contro). When conflicts : due to Pliority) occur our algmithm maintains the immediately restarted VerSlOn as wpll as the stopped version of a transaction in order to use one of the two to meet the firm deadline. At last we show that our policy generates scrializable schedules and show tbat our algorithm performs better than the traditionally used method for wide ranges of the system load for firm deadline transaction.