• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.9
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• pp.1910-1917
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• 2011

In this paper, a cloud computing platform is designed and implemented based on an open source cloud platform, OpenNebula, and Xen hypervisor on each node for efficient computer lab system. For the purpose of convenient management, a web-based user interface has been developed for the cloud virtualization system. Once individual virtual machine is allocated to a user based upon class schedule, each user can access the virtual machine remotely and use appropriate operating system and application programs. The developed system can reduce computer lab upgrade cost, management cost, and administration time considerably.

• The Journal of the Korea institute of electronic communication sciences
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• v.2 no.4
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• pp.215-221
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• 2007

IPv6 is a protocol to solve the address space limitation of IPv4 by IETF. Many transition mechanism to communicate between IPv4 and IPv6 in mixed IPv4/IPv6 network are proposed. DSTM tunneling is a mechanism that dual stack in IPv6 network is able to communicate with node in IPv4 network by dynamic allocating the IPv4 address. This mechanism supports the execution of IPv4 dependent application without modification at IPv6 network. In this paper, we explain the security vulnerability at DSTM network for DHCP attack, TEP attack, and source spoofing attack then describe the result of attacks.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.5
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• pp.482-486
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• 2008

When we design a sensor nodes, a energy-consumption of sensor nodes centers on design concerns to prolong lifetime of sensor network. In recent year, many researches have attempted to study this issue. One of that is TTDD(Two-Tier Data Dissemination approach) proposed to support a sensor network which includes several mobile sensor nodes. But it gives rise to a problem which increasing control packet for the formation and maintenance a grid structure. Therefore, we proposed a Energy-Efficient Routing Protocol used a permanent grid structure for reducing control packets in a sensor network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12A
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• pp.1160-1170
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• 2010

Existing multipath routing mechanism has much overhead to maintain the state of nodes on the multipath route and does not guarantees completely disjoint multipath construction from source to destination. In this paper, we propose an Explicit Disjoint Multipath (EDM) routing algorithm to enhance energy efficiency through removing the flooding mechanism for route discovery process, minimizing the number of nodes participating in route update and balancing the traffic load for entire network. EDM constructs logical pipelines which can create disjoint multipaths in logical way. Then it physically performs anchor node based geographic routing along the logical pipeline in order to build multipath to the destination. EDM can provide the distribution effect of traffic load over the network, help to balance the energy consumption and therefore extend the network lifetime.

• Journal of Internet Computing and Services
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• v.7 no.1
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• pp.143-150
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• 2006

The quickest path problem deals with the transmission of a message of size ${\sigma}$ from a source to a destination with the minimum end to end delay over a network with bandwidth and delay constraints on the links. We consider two basic modes and four variations for the message delivery at the nodes reflecting the mechanisms such as circuit switching. Internet protocol, and their combinations, For each of first five modes, we present O($m^2+mnlogn$) algorithm to compute the quickest path for a given message size ${\sigma}$, For the last mode, the quickest path can be computed in O(m+nlogn) time.

• Journal of the Korea Society for Simulation
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• v.17 no.1
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• pp.1-8
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• 2008

If a sink can move in sensor networks, the routing change can be more occur. If the sink has the mobility, it moves in sensor network area so that the connection between the sink system and sensor nodes will be changed continuously. Hence, the overhead can occur cased by the many routing changed. Therefore, the dynamic routing scheme is needed to support the mobile sink connection. In this paper, we propose the previous connection assignment scheme. The mobile sink can have low cost overhead from calculating dynamic rerouting that it determines the new virtual path before the physical path setup.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.8
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• pp.2096-2105
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• 1998

As there can be coincident bursts which may result in congetsion in a node of ATM network, reactive flow control schemes are required to guarantee user's Quality of Service. But, the high speed characteristics of ATM networks make it difficult to control source transmission rate in reacting to congestions in intermediate nodes. Therefore, flow control in Customer Premise Network may be more efficient than end-to-end flow control. In this paper, we propose a management model for flow ontrol in CPN and new Network Access Flow/Congestsion control scheme to utilize efficiently Virtual Path Connection.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.5
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• pp.1146-1154
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• 2010

A virtual machine lease service in the cloud computing environment has been implemented using the open source cloud computing platform, OpenNebula. In addition, a web-based cloud user interface is developed for both convenient resource management and efficient service access. The present virtual machine allocation scheme adopted in OpenNebula has performance reduction problem because of not considering CPU allocation scheduler of the virtualization software. In order to address this problem we have considered both the priority of the idle CPU resources of the cluster and credit scheduler of Xen, which resulted in performance improvement of the OpenNebula virtual machine scheduler. The experimental results showed that the proposed allocation scheme provided more virtual machine creations and more CPU resource allocations for cloud service.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1836-1837
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• 2007

무선 센서 네트워크에서 소스(Source)에서 Sink까지의 데이터 수집(Data Dissemination)은 정확한 정보를 제공, 구축하는데 있어 중요한 부분 중에 하나이다. 본 논문에서는 필요한 정보만을 신속하고 정확하게 얻기 위하여 모바일 싱크(Mobile Sink)을 이용한다. 모바일 싱크(Mobile Sink) 대해서 에너지를 효율적으로 사용할 수 있는 라우팅 기법을 소개하고, 모바일 싱크(Mobile Sink)가 이동할 때 네트워크의 연결 유지 시간(network lifetime)을 연장시키기 위해 Source에서 모바일 싱크(Mobile Sink)까지 데이터 수집(Data Dissemination)을 기법을 제안한다. 제안된 기법으로 Source와 Mobile Sink까지 가상 좌표를 통해 data dissemination path를 효율적으로 설정하고, 모바일 싱크(Mobile Sink)가 다른 좌표로 이동하였을 경우 전 좌표에서 설정되었던 경로와 새로운 좌표에서 설정된 경로를 유지, 수정을 통해 over-hearing 현상을 줄임으로써 효율적으로 에너지를 소비하도록 한다. 제안된 기법은 무선 센서 네트워크 환경에서 노드들의 수명을 연장시키고, 데이터 전송 시간을 단축시켜 더 빠른 데이터 수집(Data Dissemination)을 수식적으로 결과를 보여 준다.

• Annual Conference of KIPS
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• 2019.05a
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• pp.62-64
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• 2019

4차 산업 혁명에 들어서며 블록체인 기술이 크게 주목받고 있다. 블록체인의 간단한 정의는 분산 환경에서 모든 노드들이 수정할 수 없는 원장을 관리 하는 것이다. 블록체인은 크게 public 블록체인과 private 블록체인으로 구분할 수 있다. 이중 private 블록체인에 대한 연구가 활발히 이뤄지고 있고, 실제 많은 기업이나 연구소에서 실제 환경이나 시스템에 적용 시키려는 노력을 하고 있다. 많은 블록체인 플랫폼 중 하이퍼레저는 가장 활발히 개발이 진행되고 있는 오픈 소스 프로젝트 중 하나이다. 하이퍼레저는 Linux Foundation에서 주관하는 프로젝트로 그 중 가장 널리 알려져 있는 플랫폼으로 패브릭이 있다. 패브릭은 private 블록체인 기술로 비즈니스 상황에서 조직간 블록체인 환경을 구성하는 것에 초점이 맞춰져 있는 플랫폼이다. 패브릭은 클라이언트가 트랜잭션을 제출한 후 원장에 저장될 때까지의 과정을 독립적으로 실행되는 3 단계로 구분해 놓고 있다. 3단계는 실행, 순서화, 검증 단계로 이루어져 있다. 본 논문에서는 실행과 순서화 단계에 대해 처리시간 분석을 진행한다. 분석한 데이터를 기반으로 어떤 단계의 영향이 가장 큰지 살펴보고 차후 연구에 이용할 것이다. 차후 연구는 실행과 순서화 단계에 대한 처리시간을 줄일 수 있는 연구를 진행할 것이다.