• Journal of KIISE
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• v.43 no.12
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• pp.1404-1411
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• 2016

Network virtualization is a technique that abstracts the physical network to provide multiple virtual networks to users. Virtualized network has the advantage to offer flexible services and improve resource utilization. In SDN architecture, network hypervisor serves to virtualize the network through address virtualization, topology virtualization and policy virtualization. Among them, address virtualization refers to the technique that provides an independent address space for each virtual network. Previous work divided the physical address space, and assigned an individual division to each virtual network. Each virtual address is then mapped one-to-one to a physical address. However, this approach requires a lot of flow entries, thus making it disadvantageous. Since SDN switches use TCAM (Ternary Contents Addressable Memory) for the flow table, it is very important to reduce the number of flow entries in the aspect of cost and scalability. In this paper, we propose a LISP based address virtualization, which separates address spaces for the physical and virtual addresses and transmits packet through tunneling, in order to resolve the limitation of the previous studies. By implementing a prototype, we show that the proposed scheme provides better scalability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10A
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• pp.912-921
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• 2005

Optical burst switching(OBS) is a promising solution for building terabit optical routers and realizing If over WDM. Channel scheduling Algorithm for reduce contention is one of the major challenges in OBS. We address the issue of how to provide basic burst channel scheduling in optical burst switched WDM networks with fiber delay lines(FDLs). In OBS networks the control and payload components or a burst are sent separately with a time gap. If CHP arrives to burst switch node, because using scheduling algorithm for data burst, reservation resources such as wavelength and transmit data burst without O/E/O conversion, because contention and void between burst are happened at channel scheduling process for data burst that happened the link utilization and bust drop probability Existent proposed methods are become much research to solve these problems. Propose channel scheduling algorithm that use Release Time of bust to emphasize clearance between data and data dissipation that is happened in data assignment in this treatise and maximize bust drop probability and the resources use rate (RTUC : Release Time Unscheduled Channel). As simulation results, Confirmed that is more superior in terms of data drop and link utilization than scheduling algorithm that is proposed existing. As simulation results, confirmed improved performance than scheduling algorithm that is proposed existing in terms of survival of burst, efficiency resource and delay. However, In case load were less, degradation confirmed than existent scheduling algorithm relatively, and confirmed that is superior in data drop aspect in case of load increased.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.4
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• pp.436-444
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• 2018

Currently, the new substation automation uses the international standard IEC 61850 communication protocol. KEPCO is also constructing a new substation based on IEC 61850 from 2013 through the pilot application and research and development starting from 2007. However, there are few cases where existing substations(Transformer, T/L GIS, D/L GIS, etc.) have been used, and RTU based substations operating systems have been changed to SA substations based on IEC 61850. Therefore, the introduction of IEC 61850 in existing substation facilities has the advantage of enhancing the substantiality of the substation by reusing existing facilities, improving the interoperability with the latest substations introduced, and converting existing substations into systems suitable for unmanned operation. In this paper, we introduce a case of changing the existing RTU based substation operation system to digital substation using IEC 61850 field information processor, Ethernet switch and SA operation system. Also, IEC 61850 client authentication program and Wireshark, which is a packet analysis tool, verify IEC 61850 conformance and its feasibility.