• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.163-167
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• 2005

A research to evaluate efficiency of design optimization was performed for aerodynamic design optimization problem in distributed computing environment. The aerodynamic analyses which take most of computational work during design optimization were divided into several jobs and allocated to associated PC clients through network. This is not a parallel process based on domain decomposition rather than a simultaneous distributed-analyses process using network-distributed computers. GBOM(gradient-based optimization method), SAO(Sequential Approximate Optimization) and RSM(Response Surface Method) were implemented to perform design optimization of transonic airfoil and to evaluate their efficiencies. One dimensional minimization followed by direction search involved in the GBOM was found an obstacle against improving efficiency of the design process in distributed computing environment. The SAO was found quite suitable for the distributed computing environment even it has a handicap of local search. The RSM is apparently the fittest for distributed computing environment, but additional trial and error works needed to enhance the reliability of the approximation model are annoying and time-consuming so that they often impair the automatic capability of design optimization and also deteriorate efficiency from the practical point of view.

• 디지털콘텐츠학회 논문지
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• 제6권4호
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• pp.267-272
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• 2005

유비쿼터스 컴퓨팅 환경은 미래 생활을 대변하는 새로운 패러다임으로 IT와 개인 생활에 많은 변화를 일으킬 것으로 기대된다. 그러나 유비쿼터스 컴퓨팅 환경은 방대한 정보를 언제 어디서든 획득할 수 있고, 공유할 수 있어서 보안위협 및 개인의 프라이버시 침해와 같은 역기능의 문제가 심화되고 있는 추세이다. 본 논문에서는 유비쿼터스 컴퓨팅 환경에서 RFID 기술 도입에 따른 역기능을 최소화하기 위한 방안에 대해 연구하였다. 본 논문에서는 유비쿼터스 컴퓨팅 환경의 중요한 부분인 RFID시스템에서 발생할 수 있는 보안 및 프라이버시 위험요인들과 보안 요구사항에 대해 알아보았다. 그리고 이러한 위험요인에 대해 현재 진행되고 있는 기술적 해결방법들을 살펴보았다.

• 인터넷정보학회논문지
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• 제17권1호
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• pp.7-14
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• 2016

최근 클라우드 컴퓨팅 기술이 발전함에 따라, 언제 어디서나 스마트 폰이나 컴퓨터로 접속하여 업무를 처리할 수 있다. 또한 IT 인프라를 구축하기 위한 초기투자비용과 유지보수에 대한 부담을 줄이는 방안으로 적합하다고 여겨지면서 클라우드 컴퓨팅은 발전하였다. 클라우드 컴퓨팅의 수요가 급격하게 늘어남에 따라, 데이터센터의 환경을 유지하기 위해 소비되는 전력에 관한 문제가 발생하였다. 이 문제를 해결하기 위해서는 먼저 소비전력을 측정할 수 있어야 한다. 비록 전력측정기를 이용하여 소비전력을 측정하는 것은 정확한 소비전력을 얻을 수 있지만, 추가비용이 발생한다. 따라서 본 논문에서는 전력측정기에 의존하지 않고 소비전력을 예측하는 방안을 제시한다. 제시한 방안의 정확성을 입증하기 위해 클라우드 컴퓨팅 환경에서 CPU와 Hard disk 테스트를 실시하였다. 테스트가 진행되는 동안, 제안한 방안과 전력측정기에 의해 예측 값과 실제 값을 얻고. 오차율을 계산하였다. 그 결과 CPU 테스트에서 예측 값과 실제 값의 차이는 약 4.22%이고, Hard disk 테스트에서는 약 8.51%을 보였다.

• Journal of Information Processing Systems
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• 제2권1호
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• pp.28-33
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• 2006

The initial research of Task Computing in the ubiquitous computing (UbiComp) environment revealed the need for access control of services. Context-awareness of service requests in ubiquitous computing necessitates a well-designed model to enable effective and adaptive invocation. However, nowadays little work is being undertaken on service access control under the UbiComp environment, which makes the exposed service suffer from the problem of ill-use. One of the research focuses is how to handle the access to the resources over the network. Policy-Based Access Control is an access control method. It adopts a security policy to evaluate requests for resources but has a light-weight combination of the resources. Motivated by the problem above, we propose a universal model and an algorithm to enhance service access control in UbiComp. We detail the architecture of the model and present the access control implementation.

• 한국정보처리학회논문지
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• 제7권6호
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• pp.1932-1940
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• 2000

We must solve problems caused by mobile computing environments for supporting efficient mobile computing services. The problem is the use of wireless medium having high error rates and low bandwidth, and the sudden network disconnection to reduce the power consumption of a mobile host and the cost of the network connection. For these problems, we proposed the architecture of the partial connection manager and designed and implemented that in this paper. In particular, The partial connection manager creates the limited number of mobile agents according to priority and sends them in parallel to server systems and combines results of them process rapidly the user request. By applying the proposed partial connection manager to the mobile computing services called cybermarket, we knew that the mobile agent technique could be suited to the mobile computing environment and overcome the partial connection problem caused by eh mobile computing environment.

• 한국컴퓨터정보학회논문지
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• 제22권12호
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• pp.87-93
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• 2017

The purpose of this study is to design and develop of digital contents to improve computational thinking in the online education environment. First, we planned the design and development of contents with 19 experts of Software education. Digital content was designed from the point of view of improving the educational quality and the quality of contents for the improve of computing thinking. The content type is classified into the SW education area; computer science, programming, physical computing, convergent computing, computing thinking, and software education that improves the computing thinking. And we designed 45 learning programs for each SW education area. Designed learning contents were developed in 464 lessons to suit the online education environment. The content validity of the proposed content was verified by the expert group and the average CVI value was over .83. Through this, we could analyze that the developed contents will help learners to expand their computing thinking.

• 디지털산업정보학회논문지
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• 제8권3호
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• pp.57-64
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• 2012

Computing environment combined with development of internet and IT technology is changing to cloud computing environment. In addition, cloud computing is revitalized more because of propagation of LTE and suggestion of N-screen Service. Virtualization is the point technology for suggest IT resource to service form to users in this cloud computing. This technology combines other system physically or divides one system logically and uses resource efficiently. Many users can be provided application and hardware as needed using this. But, lately various attack using weak point of virtualization technology are increasing rapidly. In this study, we analyze type and weak point of virtualization technology, the point of cloud computing. And we study about function and the position which intrusion detection system has to prepare in order to detect and block attack using this.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권9호
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• pp.4063-4086
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• 2016

Cloud computing is a robust technology, which facilitate to resolve many parallel distributed computing issues in the modern Big Data environment. Hadoop is an ecosystem, which process large data-sets in distributed computing environment. The HDFS is a filesystem of Hadoop, which process data blocks to the cluster nodes. The data block placement has become a bottleneck to overall performance in a Hadoop cluster. The current placement policy assumes that, all Datanodes have equal computing capacity to process data blocks. This computing capacity includes availability of same storage media and same processing performances of a node. As a result, Hadoop cluster performance gets effected with unbalanced workloads, inefficient storage-tier, network traffic congestion and HDFS integrity issues. This paper proposes a storage-tier-aware Robust Data Placement (RDP) scheme, which systematically resolves unbalanced workloads, reduces network congestion to an optimal state, utilizes storage-tier in a useful manner and minimizes the HDFS integrity issues. The experimental results show that the proposed approach reduced unbalanced workload issue to 72%. Moreover, the presented approach resolve storage-tier compatibility problem to 81% by predicting storage for block jobs and improved overall data block placement by 78% through pre-calculated computing capacity allocations and execution of map files over respective Namenode and Datanodes.

• 융합보안논문지
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• 제8권1호
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• pp.35-42
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• 2008

사용자가 접하는 정보 시스템과 어플리케이션에 대한 관리가 중요한 문제로 대두되면서 시스템 접근과 관리를 위한 방법론이 제기되고 있다. 여러 가지 형태의 인증 기술이 사용되고 있지만, 복잡한 인증 관리 및 운용에 따른 비효율성은 유 무선 환경의 다양하고 새로운 비즈니스의 성공적인 전개를 위해서는 부적절하다. 또한 서로 다른 인증 방식을 사용하는 모바일 컴퓨팅 환경 하에서 유연하고 연속적인 서비스를 기대하기란 매우 어렵다. 유비쿼터스 컴퓨팅 환경하에서는 상호운용성 및 보안성이 지원되는 분산 인증 방안을 연구 개발하는 것은 매우 중요한 사안이다. 이에 따라 본 논문에서는 유선(fixed) 컴퓨팅 환경에서뿐만 아니라 이동(mobile) 컴퓨팅 환경까지 고려한 유비쿼터스 컴퓨팅 환경으로 확장 가능한 분산 인증의 관리 및 운용 방안에 대한 요구사항과 권한 메커니즘에 대해 살펴봄으로써, 향후 진정한 유비쿼터스 환경에서의 분산형 인증기법에 관한 적극적인 참여를 유도할 수 있을 것으로 기대한다.

• 산업경영시스템학회지
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• 제31권3호
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• pp.43-51
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• 2008

Recent advances in mobile computing technologies and platform-independent information systems have enabled to realize a ubiquitous environment. Community computing has been developed as a useful tool for realizing collaborative services in a ubiquitous environment. In this paper, we present a formal model of a ubiquitous space that takes community concept into consideration and propose two management frameworks that prevent conflicts among communities. To demonstrate the validity of the proposed frameworks, an example for coordinating two communities is provided.