• The KIPS Transactions:PartD
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• v.8D no.1
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• pp.10-23
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• 2001

Transactions in real-time active databases have the notion of activeness where transactions are generated by external effects and another transaction. In this paper, we propose the multi version concurrency control algorithm for real-time active transactions. A real-time active transaction has a timing constraint in the form of a deadline until which the user wants to complete the transaction, and is characterized by triggering relationships which mean that association between a transaction that triggers the execution of another transaction and the triggered transaction. The triggering relationship is an important factor to resolve data conflicts among real-time active transactions. The proposed concurrency control mechanism resolves data conflicts by considering triggering relationships between conflicting transactions as well as priorities and precedence relationships. The conflict resolution mechanism considers association types of the triggering relationship such as abort and commit dependency, and then resolves data conflicts in favor of higher priority transactions. We also present the experimental results of our algorithm comparing other real-time active concurrency control algorithms.

• 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 Internet Computing and Services
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• v.6 no.1
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• pp.73-84
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• 2005

ALTIBASE/sup TM/ is the relational main-memory DBMS in which a main memory is primarily used as the main storage device. We present the database replication strategies and techniques of the ALTIBASETM system in order to meet the requirement of high availability and efficient transaction processing. Our process architecture for replication management and its communication model are proposed, and database replication protocols are also described. We show the experimental result of transaction processing rate with various DBMS parameters and overall performance of database replication system as compared to standalone system.

• The Journal of Korean Association of Computer Education
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• v.4 no.2
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• pp.51-61
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• 2001

With the advance of computer and communication technologies, a lot of virtual schools provide web-based classes that provide learning environments out of temporal and spatial constraints and many research works on the web-based classes have been proposed. Various techniques are required to build the virtual schools efficiently. One of them is the scheme for transaction management. However, existing transaction management schemes have inappropriate features for supporting web-based classes. In this paper, we propose a new locking-based transaction processing protocol that satisfies the requirements after presenting the requirements for transaction management to support web-based classes. In the protocol, a new method, called mark, is adopted to satisfy the requirements. The proposed protocol also eliminates unnecessary delays or abortions and thus, the proposed protocol can improve the performance of database systems.

• Journal of Internet Computing and Services
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• v.1 no.2
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• pp.11-18
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• 2000

In this paper we present a new extensible model based upon the concept of subtransactions in real-time transaction systems. The nested transaction model originally proposed by J. Moss is extended for real-time uniprocessor transaction systems by adding explicit timing constraints. Based upon the model, an integrated concurrency control and scheduling algorithm is developed, that not only guarantees timing constraints of a set of real-time transactions but also maintains consistency of the database. The algorithm is based on the priority ceiling protocol of Sha et al. We prove that the Real-Time Nested Priority Ceiling Protocol prevents unbounded blocking and deadlock, and maintains the serializability of a set of real-time transactions. We use the upper bound on the duration that a transaction can be blocked to show that it is possible to analyze the schedulability of a transaction set using rate-monotonic priority assignment. This work is viewed as a step toward multiprocessor and distributed real-time nested transaction systems. Also, it is possible to be extended to include the real-time multimedia transactions in the emerging web-based database application areas.

• Journal of Korean Institute of Industrial Engineers
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• v.27 no.1
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• pp.30-36
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• 2001

We present a new algorithm for mining association rules in the large database. Association rules are the relationships of items in the same transaction. These rules provide useful information for marketing. Since Apriori algorithm was introduced in 1994, many researchers have worked to improve Apriori algorithm. However, the drawback of Apriori-based algorithm is that it scans the transaction database repeatedly. The algorithm which we propose scans the database twice. The first scanning of the database collects frequent length l-itemsets. And then, the algorithm scans the database one more time to construct the data structure Common-Item Tree which stores the information about frequent itemsets. To find all frequent itemsets, the algorithm scans Common-Item Tree instead of the database. As scanning Common-Item Tree takes less time than scanning the database, the algorithm proposed is more efficient than Apriori-based algorithm.

• Journal of Information Technology Applications and Management
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• v.12 no.4
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• pp.59-70
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• 2005

Flash memories are one of best media to support portable computer's storages in mobile computing environment. The features of non-volatility, low power consumption, and fast access time for read operations are sufficient grounds to support flash memory as major database storage components of portable computers. However, we need to improve traditional transaction management scheme due to the relatively slow characteristics of flash operation as compared to RAM memory. in order to achieve this goal, we devise a new scheme called Flash Two Phase Locking (F2PL) scheme for efficient transaction processing. F2Pl improves transaction performance by allowing multi version reads and efficiently handling slow flash write/erase operation in lock management process. We also propose a simulation model to show the performance of F2PL. Based on the results of the performance evaluation, we conclude that F2PL scheme outperforms the traditional scheme.

• Journal of Korea Multimedia Society
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• v.6 no.4
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• pp.583-593
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• 2003

Engineering design applications require the support of long transactions in cooperative environments. The problem of the existing copy/update/merge approaches is that the partial effects of a committed transaction may be not part of the merged version. This paper introduces a new cooperative transaction model, which allows updates to be progressively notified or propagated into other transactions accessing the same object. To support incremental update propagation and notification, we use the term dynamic dependency to define the intertransaction dependency relationships among all the objects checked out from the public database. Consistency in multiple copies of the same object is achieved by a two-phase delta-merge protocol. Our model provides a synchronization of cooperative updates performed in several workspaces without using locking mechanisms.

• The KIPS Transactions:PartD
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• v.8D no.5
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• pp.473-482
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• 2001

Integrated heterogeneous database systems provide the unified interface for users and applications today in order to access the underlying diverse data sources located in different sites. The multiple heterogeneous data sources have the different and specialized data structures and transaction processing capabilities. Because of local autonomy, the local system does not have the capability of cooperation to control the global transaction. Hence designing the global transaction manager with supporting the global serializability is difficult task. To resolve the well-known indirect conflict, we define the global transaction model by using the characteristics of global integrity constraints. And then we propose the site-locking operation and its protocol to manage the global transaction. The correctness and analysis of our site-locking protocol is proved and performance gain over the related other methods is also estimated in this paper.

• International Journal of Contents
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• v.12 no.1
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• pp.60-64
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• 2016

As new applications of cloud data management system (CDMS) such as online games, cooperation edit, social network, and so on, are increasing, transaction processing capabilities for CDMS are required. Several transaction processing methods for cloud data management system (CDMS) have been proposed. However, existing transaction processing methods have some problems. Some of them provide limited transaction processing capabilities. Some of them are hard to be integrated with existing CDMSs. In this paper, we proposed a new concurrency control method to support transaction processing capability for CDMS to solve these problems. The proposed method was designed and implemented based on Spark, an in-memory distributed processing framework. It uses RDD (Resilient Distributed Dataset) model to provide fault tolerant to data in the main memory. In our proposed method, database stored in CDMS is loaded to main memory managed by Spark. The loaded data set is then transformed to RDD. In addition, we proposed a multi-version concurrency control method through immutable characteristics of RDD. Finally, we performed experiments to show the feasibility of the proposed method.