• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3B
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• pp.375-390
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• 2004

Domain Name System(DNS), one of the most important Internet services, handles mapping from host names to Internet addresses and vice versa, and precedes many Internet applications such as Web, e-mail, file transfer, etc. In this paper, we propose a structural design of a generic name server system providing name services for a huge domain for the purpose of improving the performance as well as the reliability of the system. We demonstrate the validity of the design by implementing and running a testbed system. Our testbed employs a couple of master name sowers for distributing the service overhead over two, rather than one, servers and for achieving high availability of the system as a whole. We suggest the use of dynamic update to add and delete records from a zone for which the name server has authority. The slave name servers located remotely then get a new, updated copy of the zone via incremental zone transfers(IXFRs). The experiments with the implemented testbed show that the proposed structure would easily manage increasing demands on the server power, and be highly available in the face of transient faults of a module in the system.

• International Journal of Contents
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• v.12 no.3
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• pp.29-33
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• 2016

Cloud computing makes extensive use of virtual machines that permit for workloads, as well as resource usage, to be isolated from one another, and a hypervisor can be used by a virtual machine to construct cloud computing infrastructure. However, the hypervisor has high resource usage when constructing virtual machines, which results in a waste of allocated resources when not activated. Docker provides a more light-weight method to obtain agile computing resources based on a container technique that handles this problem. In this study, we have chosen this specific tool due to the increasing popularity of MapReduce and cloud container technologies such as Docker. This study aims to automatically configure Twister workloads for container-driven clouds. Basically, this is the first attempt towards automatic configuration of Twister jobs on a container-based cloud platform VM for many workloads.

• The Transactions of the Korea Information Processing Society
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• v.6 no.4
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• pp.1009-1021
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• 1999

This paper describes the design principles and structure of a prototype system for collaborative authoring over a wide area network. The system includes extensive support for commenting and comment review, facilities for document space navigation, and tools for controlling and monitoring work group activity, including document locking and activity recording. The operational prototype provides a testbed for the examination of human computer interaction, group interaction, group support, document structures, and the problem and the history of efforts to address it.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.1137-1140
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• 1999

In this thesis, we research about Communication System Construction and Test-Bed Realization Method and Software’s Design with written program into Embedded Micro Controller’s restricted memory region using a DSP Chip to deal with mainly high speed communication. Tools used for modern communication network control use TI or AMD general chip class, but nevertheless responsibility for the point at issue, Analog Device is architecture design model moderated for small communication system. In this thesis, we present extended model, and realize basic case.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.9-12
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• 1999

The 6Bone is an environment supporting experimentation with the IPv6 protocols and products implementing it. Several functions of IPv6 remain loosely defined or undefined but the protocols related on IPv6 are being developed continuously. It is clear that ATM(Asynchronous Transfer Mode) technology is playing a important role in the evolution of the Internet as a transmission medium. In this paper, we suggest a design plan for the 6Bone overlayed on the existing ATM network, KOREN(Korea Research and Education Network). The planed 6Bone will become a good testbed to develop new networking technology and new services related on IPv6.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2005.04a
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• pp.185-188
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• 2005

This paper suggests a control method for efficient topology/parameter evolution in a bond-graph-based GP design framework that automatically synthesizes designs for multi-domain, lumped parameter dynamic systems, We adopt a hierarchical breeding control mechanism with fitness-level-dependent differences to obtain better balancing of topology/parameter search - biased toward topological changes at low fitness levels, and toward parameter changes at high fitness levels. As a testbed for this approach, an eigenvalue assignment problem, which is to find bond graph models exhibiting minimal distance errors from target sets of eigenvalues, was tested and showed improved performance for various sets of eigenvalues.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.10
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• pp.877-888
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• 2012

Network virtualization technology is a crucial research issue of Future Internet which pursues a service-oriented architecture so-called NaaS (Network as a Service) or SDN (Software Defined Network). Network virtualization is expected to play an important role in Future Internet researches as a network testbed technology which enables innovative protocols to be experimented independently on a common testbed environment. We propose a control framework in order to provide user defined topology and bandwidth services with network virtualization and to separate and manage multiple-user traffics in a small and medium scale - single domain research network. The proposed framework (VIMS; Virtual network Integrated control and Management System) supports testbed expansions without any changes of heterogeneous virtual network support equipments through accommodation of each equipment's control plane. The framework shows a feasibility through applied to KOREN and we describe the differences and further study directions for improvement the framework comparing with GENI control framework.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.5
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• pp.416-422
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• 2016

This paper presents preliminary performance analysis of a satellite formation flying testbed, which is under development by Astrodynamics and Control Laboratory, Department of Astronomy, Yonsei University. A model reference adaptive controller (MRAC) with a first-order reference model is chosen to enhance the response of reaction wheel system which is subject to uncertainties caused by unmodelled dynamics and measurement noise. In addition, an on-line parameter estimation (OPE) technique based on the least square is combined to eliminate the effect of angular measurement noise by estimating the moment of inertia. Both numerical simulations and hardware experiments with MRAC support the effectiveness and applicability of the adaptive control scheme, which maintains the tracking error below $0.25^{\circ}$ for the entire time span. However, the high frequency control input generated in hardware experiment strongly suggests design modifications to reduce the effect of deadzone.

• KIISE Transactions on Computing Practices
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• v.21 no.1
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• pp.1-12
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• 2015

To realize futuristic services with agility, the role of the experimental facility (i.e., testbed) based on integrated resources has become important, so that developers can flexibly utilize the dynamic provisioning power of software-defined networking and cloud computing. Following this trend, an OpenFlow-based SDN testbed environment, denoted as OF@TEIN, connects multiple sites with unique SmartX Racks (i.e., virtualization-enabled converged resources). In this paper, in order to automate the multi-point L2 (i.e., Ethernet) inter-connection of OpenFlow islands, we introduce an automated tool to configure the required Network Virtualization using Generic Routing Encapsulation (NVGRE) tunneling. With the proposed automation tool, the operators can efficiently and quickly manage network inter-connections among multiple OpenFlow sites, while letting developers to control their own traffic flows for service realization experiments.

• Journal of the Korean Geotechnical Society
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• v.32 no.11
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• pp.97-108
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• 2016

Lunar rover plays an important role in lunar exploration. Especially, performance of rover wheel related to interaction with lunar soil is of great importance when it comes to optimization of rover's configuration. In this study, in order to investigate the motion performance of lunar rover's wheel on Korean Lunar Soil Simulant (KLS-1), a single wheel testbed was developed and used to carry out a series of experiments with two kinds of wheel with grousers and without grousers which were used to perform the experiments. Wheel traction performance was evaluated by using traction parameters such as drawbar pull, torque and sinkage correlated with slip ratio. The results showed that the single wheel testbed was suitable for evaluation of the performance of wheel and rover wheel with grousers which was likely to have higher traction performance than that without grousers in Korean Lunar soil simulant. The experimental results could be utilized in verification of the optimum wheel design and effectiveness of wheel traction for Korean lunar rover.