• Journal of the Korea Computer Industry Society
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• v.5 no.9
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• pp.1063-1068
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• 2004

A log file in web server stores various information of web server. The web server information is good reference information to improve web service quality. Also if web server occurs any fault, log file information is important information to find out occurred error. Currently, many of web server manager that they have wire have disadvantages in mobility. In order to solve above problem, this paper represent web server manager based mobile. Incase web server manager based mobile, it can immediately know recent log information accessing real-rime as also anytime, anywhere

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2005.11a
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• pp.471-474
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• 2005

원격 에이전트 서버는 에이전트 개발자가 제어권한올 가지지 못한다. 원격 에이전트 서버 중 일부가 다운된 상황에서는 에이전트를 정상적으로 동작시키기 어렵다. 이런 경우 일반적으로 이용하는 방법은 이동 에이전트가 각 에이전트 서버에 도착하면 복제본을 저장해 두는 것이다. 그러나 서버 고장 상태로부터 온라인 상태로 돌아올 때까지 복제본을 이용할 수 없게 되므로 적합한 해결책 되지 못한다. 본 논문은 에이전트 서버 고장시 이동 에이전트가 계속 동작할 수 있는 결함허용 처리기법올 제안한다. 제안 기법은 이동 에이전트를 생성하는 홈 에이전트 서버와 이동 에이전트가 방문한 이전 에이전트 서버에서 수행되며 원격 에이전트 서버에 고장이 발생한 경우 제안기법을 통해 결함허용을 처리하며 실험을 통해 제안 기법에서의 요소별 오버헤드를 분석한다.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11a
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• pp.437-440
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• 2003

본 논문은 P2P 네트워크에서 어플리케이션 레벨의 영속성있는 저장 시스템에 대해서 살펴본다. 인터넷 클라이언트의 성능 향상과 인터넷 접속 기술의 발달로 Peer-to-Peer (P2P)라는 키워드로 대표되는 다양한 파일 저장, 검색, 공유 어플리케이션이 소개되었다. 그러나, 기존의 서버 기반의 분산 저장 방식은 xDSL 기반의 가변 IP 기반의 현재 인터넷 환경에서 불안정한 성능을 보이고, 파일을 저장하고 나서 검색 발견의 확률이 떨어지는 문제점을 가진다. 본 논문에서는 시스템의 가용성(Availability)을 높이기 위한 파일의 분할 저장, 중복 저장 방법을 소개하고 이의 효과를 분석해 보인다.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.16-21
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• 2000

XML 문서와 같은 구조적 문서는 관계형 데이터베이스에 저장하는 것이 적합하다. 본 논문에서는 XML 문서의 각 엘리먼트를 관계형 데이터베이스에 검색을 위해 적정 노드까지만 깊이 우선 탐색 순서쌍에 의해 저장하고, 검색된 문서의 재생성 속도를 향상하기 위해 문서전체를 저장하는 방법을 제시하였다. 또 위에서 제시한 방법을 저장 시스템과 분석 검색하는 시스템을 서로 다른 사이트로 분리하는 것을 제안한다. 이를 통해 XML 문서를 서로 다른 사이트로 분리함으로써 서버의 부담을 줄여 저장 및 검색 성능을 향상한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.5
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• pp.1229-1240
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• 1998

In this paper, we provide a design of DAVIC VOD service system with proxy servers which perform caching of video streams. Proxy servers are placed between a service provider system and service consumer systems. They provide video services to consumers on behalf of the service provider, therefore they reduce the loads of service providers and network. The operation of a proxy server depends on whether the requested program is in its storage. If this is the case, the prosy servere takes all the controls, but if the proxy does not have the program, it forwards the service request the proxy server takes all the controls, but if the prosy does not have the program, it forwards the service request to a service provider. While the service provider system provides the program to the consumer, the proxy copies and caches the program. The proxy server executes cache replacement, if necessary. We show by simultion that the LFU is the most efficiency caching replacement algorithm among the typical algorithms such as LRU, LFU, FIFO.

• Journal of Korea Multimedia Society
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• v.6 no.6
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• pp.1100-1110
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• 2003

Design and implementation of remote procedure cail (RPC) resource service system based on the XML considering the request delegation between the servers are described for the resource application and efficient processing of distributed environment. For this purpose, the request information about several server, which would be used by client, is encoded into XML document based on XML-DOM and transferred to server. Server classifies the client requests using objects which can deal with the XMLL-DOM. For the request delegation between the servers, server saves the request result of client in XMLL-DOM structure without replying it immediately, and makes the client request delegated to another server in XML-DOM's request information. In addition, the resource repository are managed for resource transparency of distributed environment. As a result, resource application and processing efficiency are improved by reduction of response time caused by integration of RPC and XML-RPC services and request delegation between the servers. Extension of asynchronous and average blocking time of client were reduced and information of resource which can be used by client was offered.

• KIISE Transactions on Computing Practices
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• v.23 no.2
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• pp.128-133
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• 2017

In recent years, the number of systems for the analysis of large volumes of data is increasing. Hadoop, a representative big data system, stores and processes the large data in the distributed environment of multiple servers, where system-resource management is very important. The authors attempted to detect anomalies from the rapid changing of the log data that are collected from the multiple servers using simple but efficient anomaly-detection techniques. Accordingly, an Apache Hive storage architecture was designed to store the log data that were collected from the multiple servers in the Hadoop ecosystem. Also, three anomaly-detection techniques were designed based on the moving-average and 3-sigma concepts. It was finally confirmed that all three of the techniques detected the abnormal intervals correctly, while the weighted anomaly-detection technique is more precise than the basic techniques. These results show an excellent approach for the detection of log-data anomalies with the use of simple techniques in the Hadoop ecosystem.

• Journal of KIISE:Databases
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• v.32 no.6
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• pp.616-627
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• 2005

In the shared storage file system, systems can directly access the shared storage device through specialized data-only subnetwork unlike in the network attached file server system. In this shared-storage architecture, data consistency is maintained by some designated set of lock servers which use control network to send and receive the lock information. Furthermore, lease mechanism is introduced to cope with the control network failure. But when the control network is partitioned, participating systems can no longer make progress after the lease term expires until the network recovers. This paper addresses this limitation and proposes a method that allows partitioned systems to make progress under the partition of control network. The proposed method works in a manner that each participating system is rotationally given a predefined lease term periodically. It is also shown that the proposed mechanism always preserves data consistency.

• Smart Media Journal
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• v.6 no.3
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• pp.21-28
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• 2017

There is growing interest in the use of cloud services these days because the amount of sensitive physical information related to u-fitness-based exercise management increase in explosive. However, it is possible to illegally access information stored in a cloud server, and to find out who owns the information, even, to illegally deduce an association among the information stored in its memory. The cloud server may also intentionally pass over the owner's legitimate operation requests such as modification and deletion of stored information, and may lose or damage information due to its malfunction. So, it is strongly required to solve the above problems because we can not trust the cloud server entirely. In this paper, we propose a protocol to preserve the privacy of the owner for u-Fitness-based exercise management in a cloud computing environment. And we show that our proposed architecture is applicable in real environment through security analysis and performance analysis.

• Journal of KIISE:Databases
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• v.31 no.3
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• pp.274-286
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• 2004

In mobile client-server environments, mobile clients usually are disconnected with their server because of high cost of wireless communication and keep their own local copies to provide efficient updating the cached map. The update of the server database leads to invalidation of the cached map in the client side. To solve the issues of invalidation of the cached map, it is not efficient to resend part of the updated server database to clients whenever the updating of the server database occurs. This paper proposes a log-based update propagation method to propagate the server's update into its relevant clients by using only update logs. Too many logs increasingly accumulate as the sever database is updated several times. The sequential search of the relevant log data for a specific client is time-consuming. Sending of unnecessary logs should be avoided for reducing the overhead of communication.'re solve these problems, we first define unnecessary logs and then suggest log reduction methods to avoid or cancel creating unnecessary logs. The update log index is used for quickly retrieving relevant logs.