• Journal of the Korea Society of Computer and Information
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• v.16 no.1
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• pp.101-115
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• 2011

PECOLE (Peer-to-Peer Collaborative Environment) is a P2P-based multimedia distributed collaborative environment supporting a collaborative workspace which is composed of a variety of collaborative applications such as multi-chat, video conferencing, screen sharing and etc. Unfortunately, due to the PECOLE's simple group management, it is impossible to perform collaboration activities while joining multiple groups. In this paper, we present the design and implementation of PECOLE+ which is an extension of PECOLE. PECOLE+ resolves the drawback of PECOLE by providing the Group Management Service and the Workspace Management Service. The Group Management Service provides functionalities such as creating groups, joining multiple groups, and searching groups, and etc. The Workspace Management Service provides each group with an associated workspace, supporting the execution of collaborative applications over the workspace. In addition, any collaborative applications with the provided plug-in interfaces can be executed over the workspace as a PECOLE+ collaborative application.

• Journal of Internet Computing and Services
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• v.14 no.1
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• pp.53-62
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• 2013

It is common among users to have multiple computing devices as well as to access their files or do work at different locations. To achieve file consistency as well as mobility in this scenario, an efficient approach for workspace synchronization should be used. However, file synchronization alone cannot guarantee the mobility of work environment which allows activities to be resumed at any place and time. This paper proposes a ubiquitous synchronization approach which provides cloud-based access to a user's workspace. Efficient synchronization is achieved by combining session monitoring with file system management. Experimental results show that the proposed mechanism outperforms Cloud Master-replica Synchronization in terms of number of I/O operations, CPU utilization, as well as the average and maximum latencies in responding to client requests.

• Journal of Information Technology Services
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• v.8 no.1
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• pp.193-202
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• 2009

Cloud computing emerges as a new computing paradigm which targets reliable and customizable services. The term builds on decades of research in virtual machine, distributed and parallel computing, utility computing, and more recently networking, web service, and software as a service. In this paper, we provide a seamless connection migration of web services. This is useful for cloud computing environment in which many client terminals have mobility. With the wireless internet facility, those mobile users can move place to place during internet communication. Therefore, we provide solutions to the two major problems in current virtualization based migration: communication failure problems and connection re-establishment. Communication channel flushing by zero window notification helps to resolve the communication failure problems and TCP port inheritance prevents connection re-establishment errors during socket reconstruction. Thus, our web service migration facility is now able to preserve open network connections, and even for server sockets. This is a highly transparent approach, in that we did not Introduce additional messages for channel flushing and did not make any modification to the TCP protocol stack. Experimental results show that the overhead due to connection migration of web services is almost negligible when compared with time to take the conventional web service migration.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.12
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• pp.2657-2664
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• 2012

Web-based learning receives much attention as an effective learning method because users can use the learning service at any time from any space. A learning management system(LMS) provides online educational environment among teachers and students, supporting various facilities to deliver educational contents. Since most of the existing LMSs support one-way or limited two-way teaching services among teachers and students, there are a lot of difficulties in performing collaboration among students and/or collaboration among teachers and students. In this paper, we describe the development of collaborative workspaces which provides effective collaborative educational environment on Moodle which is widely accepted as a typical LMS. Through the provided various types of collaborative workspaces, users can easily perform group activities, sharing educational with appropriate access control mechanism.