• Journal of Korea Multimedia Society
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• v.7 no.8
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• pp.1097-1106
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• 2004

The typical web cluster architecture consists of replicated real servers and a virtual server that routes client requests among the real servers. In this paper, we proposed an efficient dynamic load distribution method with load prediction for the web cluster systems. The virtual server transmit status request message to real servers in other to get load states. However the load states dose not accurate during load distribution, thus the virtual server predict the load status of real servers and assign a request of the client to the minimum loaded real server. The proposed distribution methods works not related to partial breakdown of real servers, thus the system works with high availability. We also show that the proposed distribution method preserve scalable property and improve the throughput through a set of simulations.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10d
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• pp.108-111
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• 2007

네트워크가 광범위하게 발달함에 따라 악의적인 공격도 늘어나고 있다. 악의적인 공격을 막는 방법으로 침입을 차단하는 프로그램을 설치하는 것 외에도 시스템을 패치하는 것은 중요한 부분을 차지한다. 패치 분배 시스템은 대규모 네트워크 상의 시스템에 패치를 분배할 때 부하 분산을 하기 위하여 계층적 구조로 설계된다. 본 논문에서는 계층적 패치 분배 구조에서 상위 계승이 하위 계층을 효과적으로 인증하기 위한 방법을 제안한다.

• Journal of the Korean Data and Information Science Society
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• v.18 no.3
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• pp.637-644
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• 2007

We consider a life testing experiment in which several two component shared parallel system are put on test, and the test is terminated at a pre-designed experiment. The bivariate data obtained from such a system level life testing can be classified into three cases: (1) the case of failed two components with known failure times, (2) the case of one censored component and the other failed component of which the failure time might be known or unknown, (3) the case of censored two components. In this paper, the maximum likelihood estimators of parameters for Block and Basu bivariate exponential model under above censoring scheme are obtained and the results of comparative studies are presented.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.6
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• pp.2713-2719
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• 2012

According to increasing of various location-based services, distributed data stream processing techniques have been widely studied to provide high scalability and availability. In previous researches, in order to balance the load of distributed nodes, the geographic characteristics of spatial data stream are not considered. For this reason, distributed operations for adjacent spatial regions increases the overall system load. We propose a operation allocation scheme considering the characteristics of spatial operations to effectively processing spatial data stream in distributed computing environments. The proposed method presents the efficient share maximizing approach that preferentially distributes spatial operations sharing the common query regions to the same node in order to separate the adjacent spatial operations on overlapped regions.

• The Transactions of the Korea Information Processing Society
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• v.5 no.9
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• pp.2248-2255
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• 1998

The property of connectivity between DBMS and application system developed in java is very important under the distributed object environments with heterogeneous systems. In these days, mostly used JDBC 3-tier model, which supports the connectivity, has two problems: the one is the restricted connectivity needed for the Java applet as application programs and the other is the additional efforts to design and implemtnt in linking any application program with the middleware from being deficit of standard protocol. In order to solve these problems, we have worked on Enlarging the properties of JDBC 3 tier model by applying CORBA distributed object environments. Thus, the enlarged 3-tier model has an ORB-JDBC sub protocol for the client sub-protocol and a middleware whose property is supported by CORBA.