• Smart Structures and Systems
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• 제3권4호
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• pp.455-474
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• 2007

A flexibility-based distributed computing strategy (DCS) for structural health monitoring (SHM) has recently been proposed which is suitable for implementation on a network of densely distributed smart sensors. This approach uses a hierarchical strategy in which adjacent smart sensors are grouped together to form sensor communities. A flexibility-based damage detection method is employed to evaluate the condition of the local elements within the communities by utilizing only locally measured information. The damage detection results in these communities are then communicated with the surrounding communities and sent back to a central station. Structural health monitoring can be done without relying on central data acquisition and processing. The main purpose of this paper is to experimentally verify this flexibility-based DCS approach using wired sensors; such verification is essential prior to implementation on a smart sensor platform. The damage locating vector method that forms foundation of the DCS approach is briefly reviewed, followed by an overview of the DCS approach. This flexibility-based approach is then experimentally verified employing a 5.6 m long three-dimensional truss structure. To simulate damage in the structure, the original truss members are replaced by ones with a reduced cross section. Both single and multiple damage scenarios are studied. Experimental results show that the DCS approach can successfully detect the damage at local elements using only locally measured information.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제2권12호
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• pp.569-576
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• 2013

최근 많은 관심을 받고 있는 클라우드 컴퓨팅이 해결해야할 가장 큰 문제는 바로 보안이다. 일반적인 클라우드 컴퓨팅 환경에서는 사용자의 데이터 보호를 위해 수많은 분산서버를 이용하여 데이터를 저장한다. 하지만 분산서버에 저장된 데이터를 암호화 과정을 거치지 않고 그대로 저장하게 된다면, 마스터 서버에 저장된 분산파일 위치를 추적하여 그대로 유출이 되는 문제가 발생할 수 있다. 이러한 문제를 방지하기 위해 비밀키를 이용하여 분산된 데이터를 암호화해야할 필요성이 존재한다. 그러나 대용량 데이터의 경우 수십, 수백 개의 조각으로 나누어지게 되는데 분산서버마다 각각의 비밀키를 이용하게 된다면, 관리의 어려움이 존재할 뿐 아니라 분산 서버에 대한 정당한 인증, 암복호화 과정을 수없이 거치게 되어 막대한 오버헤드가 발생하게 된다. 따라서 본 논문에서는 이와 같은 문제점을 해결하기 위해 Hadoop 환경에 적합한 XOR 및 RAID기반의 효율적인 분산 저장 및 복구 기법을 제안하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권3호
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• pp.1141-1163
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• 2019

In an effort to minimize operational expenses and supply users with more scalable services, distributed applications are actually going towards the Cloud. These applications, sent out over multiple environments and machines, are composed by inter-connecting independently developed services and components. The implementation of such programs on the Cloud is difficult and generally carried out either by hand or perhaps by composing personalized scripts. This is extremely error prone plus it has been found that misconfiguration may be the root of huge mistakes. We introduce AutoBot, a flexible platform for modeling, installing and (re)configuring complex distributed cloud-based applications which evolve dynamically in time. AutoBot includes three modules: A simple and new model describing the configuration properties and interdependencies of components; a dynamic protocol for the deployment and configuration ensuring appropriate resolution of these interdependencies; a runtime system that guarantee the proper configuration of the program on many virtual machines and, if necessary, the reconfiguration of the deployed system. This reduces the manual application deployment process that is monotonous and prone to errors. Some validation experiments were conducted on AutoBot in order to ensure that the proposed system works as expected. We also discuss the opportunity of reusing the platform in the transition of applications from Cloud to Fog computing.

• International Journal of Contents
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• 제2권4호
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• pp.25-30
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• 2006

The mutual exclusion (MX) paradigm can be used as a building block in many practical problems such as group communication, atomic commitment and replicated data management where the exclusive use of an object might be useful. The problem has been widely studied in the research community since one reason for this wide interest is that many distributed protocols need a mutual exclusion protocol. However, despite its usefulness, to our knowledge there is no work that has been devoted to this problem in a mobile computing environment. In this paper, we describe a solution to the mutual exclusion problem from mobile computing systems. This solution is based on the token-based mutual exclusion algorithm.

• JSTS:Journal of Semiconductor Technology and Science
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• 제10권1호
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• pp.49-54
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• 2010

This paper describes a fast circuit simulation technique using the latency insertion method (LIM) with a parallel and distributed leapfrog algorithm. The numerical simulation results on the PC cluster system that uses the cloud computing system are shown. As a result, it is confirmed that our method is very useful and practical.

• 한국컴퓨터정보학회논문지
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• 제12권6호
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• pp.1-9
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• 2007

본 논문에서는 분산된 자원 관리를 위한 새로운 프레임워크를 제안한다. 제안된 프레임워크는 새로운 특징들을 가진다. 첫째로, 자원 관리 시스템은 시스템 속성에 의해 특징지어지는 자원 컨텐츠 정보를 사용하여 분산되어진다. 자원 컨텐츠에 의거하는 분산 시스템은 그리드를 통해 워크로드 균형을 고려한다. 또한 Quality of Service(QoS)를 위한 특수한 스케줄링 요청을 만족시킨다. 두 번째로. 분산 시스템은 계층적 peer-to-peer 네트워크를 구성한다. 이러한 peered 네트워크는 효과적인 메시지 라우팅 메커니즘을 제공한다. 제안된 프레임워크가 시뮬레이션을 통하여 분산 환경에서 QoS를 만족한다는 것을 증명하고 있다.

• 한국물환경학회지
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• 제31권5호
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• pp.491-506
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• 2015

Distributed models represent watersheds using a network of numerous, uniform calculation units to provide spatially detailed and consistent evaluations across the watershed. However, these models have a disadvantage in general requiring a high computing cost. Semi-distributed models, on the other hand, delineate watersheds using a simplified network of non-uniform calculation units requiring a much lower computing cost than distributed models. Employing a simplified network of non-uniform units, however, semi-distributed models cannot but have limitations in spatially-consistent simulations of hydrogeochemical processes and are often not favoured for such a task as identifying critical source areas within a watershed. Aiming to overcome these shortcomings of both groups of models, a hybrid watershed model STREAM (Spatio-Temporal River-basin Ecohydrology Analysis Model) was developed in this study. Like a distributed model, STREAM divides a watershed into square grid cells of a same size each of which may have a different set of hydrogeochemical parameters reflecting the spatial heterogeneity. Like many semi-distributed models, STREAM groups individual cells of similar hydrogeochemical properties into representative cells for which real computations of the model are carried out. With this hybrid structure, STREAM requires a relatively small computational cost although it still keeps the critical advantage of distributed models.

• 한국데이타베이스학회:학술대회논문집
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• 한국데이타베이스학회 1994년도 DB산업기술 활성화를 위한 학술대회 및 기술 심포지움
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• pp.49-69
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• 1994

A client/server system has become the computing architecture for the business organization which seeks competitive edges. Technically, a client/server system places application processing close to the user and thus increases performance. This paper's two primary goals are (i) to present a performance model for client/server database systems and (ii) to demonstrate analytically the effectiveness of client/server computing in comparison with other computing architectures via an illustrative example. The model is most likely to be used as a practical performance guide for client/server computing.

• 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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.462-464
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• 2004

ActiveX is the general name for a set of Microsoft Technologies that allows users to re-use code and link individual programs together to suit their computing needs. In addition ActiveX technology Provides a standard model for interapplication communication that different programming language. ActiveX is based on COM(Component Object Model), the COM standard allow developer to create code and application from a multitude of different languages and build a defined interface to that code, making it easily accessible by other application. By using ActiveX, user can access the functionality of other applications running remote computer distributed through the network and communicate over the network to build distributed applications. LabVIEW provides access to other Windows applications using ActiveX technologies. So in this paper we implement distributed application using ActiveX technology for remote control and monitoring.