• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.7
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• pp.3026-3049
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• 2016

Cloud computing promises high performance and cost-efficiency. However, most cloud infrastructures operate at a low utilization, which greatly adheres cost effectiveness. Previous works focus on seeking efficient virtual machine (VM) consolidation strategies to increase the utilization of virtual resources in production environment, but overlook the under-utilization of backup virtual resources. We propose a heuristic time sharing policy of backup VMs derived from the restless multi-armed bandit problem. The proposed policy achieves increasing backup virtual resources utilization and providing high availability. Both the results in simulation and prototype system experiments show that the traditional 1:1 backup provision can be extended to 1:M (M≫1) between the backup VMs and the service VMs, and the utilization of backup VMs can be enhanced significantly.

• Convergence Security Journal
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• v.13 no.6
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• pp.17-24
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• 2013

Recently, the cloud computing technology is emerging as an important issue in the world, and In the technology and services has attracted much attention. However, the positive aspects of cloud computing unlike the includes several vulnerabilities. For this reason, the hacking techniques according to the evolution of a variety of attacks and damages is expected. Therefore, this paper will be analyzed through case studies and experiments to the security technology trends of the cloud computing. and In the future, this is expected to be utilized as a basis for the security system design and corresponding technology development.

• Journal of Information Technology Services
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• v.7 no.4
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• pp.209-219
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• 2008

Recently the number of Internet firms providing useful information like weather forecast data is growing. However most of such information is not prepared in accordance with customers' demand, resulting in relatively low customer satisfaction. To upgrade the service quality, it is recommended to devise a system for customers to get involved in the process of service production, which normally requires a huge investment on supporting computer systems like clusters. In this paper, as a way to cut down the budget for computer systems but to improve the performance, we extend the HPC cluster system to include other Internet servers working independently on the same LAN, to make use of their idle times. We also deal with some issues resulting from the extension, like the security problem and a possible deadlock caused by overload on some non-dedicated nodes. At the end, we apply the technique in the solution of some 2D grid problem.

• ETRI Journal
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• v.46 no.3
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• pp.501-512
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• 2024

With an explosive increase of data produced annually, researchers have been attempting to develop solutions for systems that can effectively handle large amounts of data. Single-operating-system (OS) non-uniform memory access (NUMA) abstraction technology is an important technology that ensures the compatibility of single-node programming interfaces across multiple nodes owing to its higher cost efficiency compared with scale-up systems. However, existing technologies have not been successful in optimizing user performance. In this paper, we introduce a single-OS NUMA abstraction technology that ensures full compatibility with the existing OS while improving the performance at both hypervisor and guest levels. Benchmark results show that the proposed technique can improve performance by up to 4.74× on average in terms of execution time compared with the existing state-of-the-art opensource technology.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.3
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• pp.491-500
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• 2013

With the advent of big data and increased costs of SSD(HDD), domestic and foreign Internet cafes and organizations have adopted NDS(No Disk System) solution recently. NDS is a storage virtualization solution based on a kind of cloud computing. It manages Operating System and applications in the central server, which were originally managed by individual computers. This research will illustrate the way to analyze user's behaviors under NDS circumstance.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.2
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• pp.203-212
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• 2013

Recently, cloud computing is one of the parts showing the biggest growth in the IT market and is expected to continue to grow into. Especially, many companies are adopting virtual desktop infrastructure as private cloud computing to achieve in saving the cost and enhancing the efficiency of the servers. However, current digital forensic investigation methodology of cloud computing is not systematized scientifically and technically. To do this, depending on the type of each cloud computing services, digital evidence collection system for the legal enforcement should be established. In this paper, we focus on virtual desktop infrastructure as private cloud computing and introduce the most widely used around the world desktop virtualization solutions of VMware, Citrix, and Microsoft. And We propose digital forensic investigation methodology for private cloud computing that is constructed by these solutions.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.4
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• pp.1017-1023
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• 2015

The amount of smart phones has increased exponentially. Due to the periodic release of high-performance smart phones and upgraded operating system, new smart phones become out-dated over 1 or 2 years. In order to solve environmental constraints of these smart phones, virtualization technology using Thin-Client terminal has been developed. However, in the case of Virtual Machine(VM), the applications associated with sensors and a GPS device can not run because they are not included. In this paper, by implementing the device driver for Android running in a virtual machine in the x86-based systems, it is to provide Android virtualization capabilities such as using the latest smart phones in the virtual machine environment. It would like to propose a method that the virtual device driver receives sensors and GPS information from the old Android smart phones(Thin-Client) that actually work and run as if the real device exists.

• The Journal of the Korea Contents Association
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• v.6 no.10
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• pp.126-133
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• 2006

Application software streaming is a virtualization technology that enables users to use applications without installation on her/his computer. With application streaming service, a client immediately starts and uses the application as if it were installed. The application can be executed while executable codes for the application may still be streamed. Since the software streaming is based on networks, its service is affected by network failures. Network failures may cause the streamed application to stop, and to make it worse, also the system may crash because executable codes for the application can't be streamed from the streaming server. Using the Pareto principle (80 vs. 20 rule), users can be served continuously with the minimum functions that are frequently used, pre-fetched and cached if we provide a more intelligent and fault-tolerant streaming technique. This paper proposes the concept and technique named Evergreen. Using the Evergreen technique, users can continue using the streamed application while a network failure occurs, although user can access only the streamed code. We also discuss the implementation of Evergreen technique in details.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2002.11a
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• pp.520-532
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• 2002

A new architecture called the Storage Area Network(SAN) was developed in response to the requirements of high availability of data scalable growth and system performance. In order to use SAN more efficiently, most SAN operating systems support storage virtualization concepts that allow users to view physical storage devices attached to SAN as a large volume virtually. A logical volume manager plays a key role in storage virtualization. In order for mapping managers to process snap-shots and reorganizations, an efficient freespace manager is required, and it affects the overall performance of logical volume. In this thesis, we design and implement a freespace manager for logical volume manager. The freespace manager efficiently allocates physical blocks for logical blocks. Also, it processes space allocation requests for suports snapshots and reorganizations.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.757-760
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• 2012

Cloud storage system that cloud computing providers provides large amounts of data storage and processing of cloud computing is a key component. Large vendors (such as Facebook, YouTube, Google) in the mass sending of data through the network quickly and easily share photos, videos, documents, etc. from heterogeneous devices, such as tablets, smartphones, and the data that is stored in the cloud storage using was approached. At time, growth and development of the globally data, the cloud storage business model emerging is getting. Analysis new network storage cloud storage services concepts and technologies, including data manipulation, storage virtualization, data replication and duplication, security, cloud computing core.