• The Transactions of the Korea Information Processing Society
• /
• v.4 no.3
• /
• pp.639-648
• /
• 1997

As the areas of computer application are expanded, the real-time applicition enviroments that must process as many transactions as possible within their deadlines have been increased recently. Conventional disk based databaes system is not appropriate in real-time transaction processing due to delying time for disk I/O processing. When the system is overloaede, the performance of transaction scheduling technique using earliest deadline first deteriorates rapidly because it can assign the highest priority ot a transaction that has already missed or is about to miss tis deadline. Therfore, the performance of suggested transaction secheduling technique is made to improved by propos-ing the doule locking mechanism based on priority. Finally, in order to evaluate the performance of the proposed priority-based double locking techniques under single proessor and main memory database system environments, the simulation model was developed using the SLAM II language.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2001.10a
• /
• pp.125-128
• /
• 2001

이동 통신 기술의 발전은 사용자로 하여금 이동 중에도 정보를 공유할 수 있는 토대를 제공하였다. 하지만, 이동 컴퓨팅 환경에서 기존의 유선 환경에서와 같은 수준의 서비스를 제공하기 위해서는 이질적이며 분산되어 있는 다수의 정보 자원을 사용할 수 있어야 한다. 따라서, 고정된 네트워크 상의 상호 이질적인 데이터베이스에 접근하여 이동 컴퓨팅 환경의 특성에 맞게 정보를 효과적으로 처리할 수 있는 트랜잭션 모델 및 표준화된 아키텍쳐에 관한 연구가 필요하다. 본 연구에서는 표준 미들웨어에 기반 하여 위와 같은 요구사항을 만족시키는 이동 트랜잭션 모델을 제시하였다.

• Journal of KIISE:Databases
• /
• v.29 no.6
• /
• pp.502-512
• /
• 2002

Most of previous replication schemes assume lazy schemes, which asynchronously propagate replica updates to other nodes after the updating transaction commits. While lazy schemes are novel in the sense that they can resolve high deadlock frequencies of eager schemes, they suffer from the fact that users should be responsible for the data consistency. Recently replication schemes based on the messaging order of group communication have been studied. They can reduce the deadlock frequencies using the messaging order, but they have another problem of increasing execution overhead of aborted transactions at high degree of concurrency. This is because the sender node validates global serializability after multicasting replica update messages to other nodes. In this paper, we propose an efficient eager replication scheme for reducing the number of messaging and overhead of aborted transactions significantly. The proposed scheme validates any conflicts before multicasting and does not multicast when there is any conflict; hence, it can exploit performance improvement by alleviating the message traffic for replica update or by reducing the number of disk accesses and locking delay due to aborted transactions.

• Journal of KIISE:Databases
• /
• v.29 no.6
• /
• pp.500-500
• /
• 2002

Most of previous replication schemes assume lazy schemes, which asynchronously propagate replica updates to other nodes after the updating transaction commits. While lazy schemes are novel in the sense that they can resolve high deadlock frequencies of eager schemes, they suffer from the fact that users should be responsible for the data consistency. Recently replication schemes based on the messaging order of group communication have been studied. They can reduce the deadlock frequencies using the messaging order, but they have another problem of increasing execution overhead of aborted transactions at high degree of concurrency. This is because the sender node validates global serializability after multicasting replica update messages to other nodes. In this paper, we propose an efficient eager replication scheme for reducing the number of messaging and overhead of aborted transactions significantly. The proposed scheme validates any conflicts before multicasting and does not multicast when there is any conflict; hence, it can exploit performance improvement by alleviating the message traffic for replica update or by reducing the number of disk accesses and locking delay due to aborted transactions.

• The KIPS Transactions:PartD
• /
• v.11D no.3
• /
• pp.717-730
• /
• 2004

Recently. many researches on the personalization of a web-site have been actively made. The web personalization predicts the sets of the most interesting URLs for each user through data mining approaches such as clustering techniques. Most existing methods using clustering techniques represented the web transactions as bit vectors that represent whether users visit a certain WRL or not to cluster web transactions. The similarity of the web transactions was decided according to the match degree of bit vectors. However, since the existing methods consider only whether users visit a certain URL or not, users' interestingness on the URL is excluded from clustering web transactions. That is, it is possible that the web transactions with different visit proposes or inclinations are classified into the same group. In this paper. we propose an enhanced transaction modeling with interestingness weight to solve such problems and a new similarity measuring method that exploits the proposed transaction modeling. It is shown through performance evaluation that our similarity measuring method improves the accuracy of the web transaction clustering over the existing method.

• Proceedings of the Korea Database Society Conference
• /
• 1999.06a
• /
• pp.241-250
• /
• 1999

인터넷 온라인 유통업은 기본적으로 다량의 트랜잭션 발생을 전제로 한다. 본 논문에서는 디지털 프로세스 처리를 목표로 한 프로세스 에이전트를 정의하고 이들의 활동 프레임웍을 제시하고 있다. 인터넷 온라인 유통업을 대상으로 내부 프로세스를 분석해 보았으며 이를 토대로 다양한 운영층 프로세스 에이전트 유형과 특성을 정의하였다 또한, 다수의 에이전트로 구성된 프로세스 에이전트팀 조직과 활동 원칙도 제시하였다. 에이전트의 구현을 위해 멀티쓰레딩 기법을 사용하였다. 단순한 데이터처리를 담당하는 운영층 프로세스 에이전트에 대한 연구는 향후 보다 복잡한 지능을 가진 전략층 프로세스 에이전트에 대한 연구로 발전할 것이다.

• Proceedings of the Korea Inteligent Information System Society Conference
• /
• 1999.03a
• /
• pp.241-250
• /
• 1999

인터넷 온라인 유통업은 기본적으로 다량의 트랜잭션 발생을 전제로 한다. 본 논문은 디지털 프로세스 처리를 목표로 한 프로세스 에이전트를 정의하고 이들의 활동 프레임웍을 제시하고 있다. 인터넷 온라인 유통업을 대상으로 내부 프로세스를 분석해 보았으며 이를 토대로 다양한 운영층 프로세스 에이전트 유형과 특성을 정의하였다. 또한, 다수의 에이전트로 구성된 프로세스 에이전트팀 조직과 활동 원칙도 제시하였다. 에이전트의 구현을 위해 컬티쓰데딩 기법을 사용하였다. 단순한 데이터 처리를 담당하는 운영층 프로세스 에이전트에 대한 연구는 향후 보다 복잡한 지능을 가진 전략층 프로세스 에이전트에 대한 연구로 발전할 것이다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2002.04b
• /
• pp.85-87
• /
• 2002

본 논문에서는 인터넷 상에서의 물품 구입 및 판매 요구를 지원하기 위한 분산 트랜잭션 처리 모델을 제시한다. 가상 공간에서의 트랜잭션 처리를 위해서는 구입 요구와 판매 요구 조건이 부합되어야 한다. 이러한 요구 사향들을 저장하기 위해 지리적인 지역 레벨에 따라 데이터베이스를 사용하고 이들을 DNS의 계층 구조와 비슷하게 연결한다. 또한 각 판매 및 구입 요구 정보를 여러 사이트에 복제 저장함으로써 판매 및 구입 요구가 발생하면 부합되는 구입 및 판매 요구를 검색하는 시간을 줄일 수 있다. 판매 및 구입 요구 정보를 저장하는 방식에 따른 검색 시간에 대한 복잡도를 분석하여 제시하였다.

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

• Journal of the Korea Computer Industry Society
• /
• v.4 no.12
• /
• pp.1053-1068
• /
• 2003

In this paper, we propose a new scheduling method without timing covert channel of real-time transaction for secure database systems that implement mandatory access control. Our scheduling method use the wait queue based on security level to remove timing covert channel. And it use priority queue that consider transaction type, deadline, and weight. Therefore, the proposed scheduling method prevents timing covert channel because it is kept noninterference between transactions with different security level, and maximizes the sum of the weight of transactions that satisfy its deadline. The simulation results, is a comparison of traditional methods, show that our scheduling method is improved to 30%.