• Title/Summary/Keyword: 동적 결정 네트워크

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Implementation of a Kinematic Network-Based Single-Frequency GPS Measurement Model and Its Simulation Tests for Precise Positioning and Attitude Determination of Surveying Vessel (동적네트워크 기반 단일주파수 GPS 관측데이터 모델링을 통한 측량선의 정밀측위 및 자세각결정 알고리즘 구현과 수치실험에 의한 성능분석)

  • Hungkyu, Lee;Siwan, Lyu
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.33 no.2
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    • pp.131-142
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    • 2015
  • In order to support the development of a cost-effective river bathymetric system, this research has focused on modeling GPS observables, which are obtained by array of five single-frequency receivers (i.e., two references and three rovers) to estimate the high accurate kinematic position, and the surveying vessel altitude. Also, by applying all GPS measurements as multiple-baselines with constraining rover baselines, we derived the socalled ‘kinematic network model.’ From the model, the integer-constrained least-squares (LS) for position estimation and the implicit LS for attitude determination were implemented, while a series of simulation tests with respect to the baseline lengths around 2km performed to demonstrate its accuracy analysis. The on-the-fly (OTF) ambiguity resolution tests revealed that ninety-nine percents of time-to-fix-first ambiguity (TTFF) can be decided in less than two seconds, when the positioning accuracy of ambiguity-fixed solutions was assessed as the greater than or equal to one and two centimeters in horizontal and vertical, respectively. Comparing to the GPS-derived attitudes, the achievable accuracy gradually descended in sequence of yaw, pitch and roll due to the antenna geometric configuration. Furthermore, the RMSE values for the baseline lengths of three to six meters were within ±1′for yaw, and less than ±10′and ±20′for pitch and roll, respectively, but those of between six to fifteen meters were less than ±1′for yaw, ±5′for pitch, and ±10′for roll.

Topic Similarity-based Event Routing Algorithm for Wireless Ad-Hoc Publish/Subscribe Systems (Ad-Hoc 무선 환경의 발행/구독 시스템을 위한 구독주제 유사도 기반의 이벤트 라우팅 알고리즘)

  • Nguyen, Hieu Trung;Oh, Sang-Yoon
    • Journal of the Korea Society of Computer and Information
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    • v.14 no.10
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    • pp.11-22
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    • 2009
  • For a wireless ad-hoc network, event routing algorithm of the publish/subscribe system is especially important for the performance of the system because of the dynamic characteristic and constraint network of its own. In this paper, we propose a new hybrid event routing algorithm. TopSim for efficient publish/subscribe system on the wireless ad-hoc network by extending the ShopParent algorithm by considering not only network overheads to choose a Parent of the publish/subscribe tree, but also topic similarity which is closeness of subscriptions. Our evaluation shows our proposed TopSim performs better for the case where a new joining node subscribed to the multiple topics and there is a node among Parent candidate nodes who subscribe to the ones in the list of multiple topics (related topics).

Dynamic Multi-Rate Routing Sub-Layer for Mobile Ad hoc Networks (모바일 애드 혹 네트워크에서의 동적 다중전송속도 경로 배정 알고리즘)

  • Nam Yong-Sub;Choi Nak-Jung;Ryu Ji-Ho;Kwon Tae-Kyoung;Choi Yang-Hee
    • Proceedings of the Korean Information Science Society Conference
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    • 2006.06d
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    • pp.115-117
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    • 2006
  • IEEE 802.11 표준은 채널 상태에 따라 다양한 전송 속도를 지원하며, 무선랜 환경에서 이러한 특성을 활용하는 연구들이 진행되어 왔다. 그러나, 모바일 애드 혹 네트워크 환경에서 다중전송속도를 활용하는 연구는 거의 이루어지지 않았다. 본 논문은 모바일 애드 혹 네트워크에서 동적으로 다중전송속도를 활용하여 채널 효율을 높이는 알고리즘을 제안한다. 제안 기법은 MAC 계층과 네트워크 계층 중간에 위치하며 각 계층에 독립적으로 동작한다. 라우팅 프로토콜에서 결정한 다음 홉에 더불어, 제안 기법은 더 빠른 전송 속도를 갖는 중계 경로를 탐색한다. 또한, 패킷의 크기에 따라 경쟁 부하를 고려하여 선택적으로 전송 경로를 변경한다. 모의 실험을 통한 성능 평가는 제안 기법의 우수한 성능을 입증한다.

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Process Scheduling for High-Performance Network I/O Virtualization over Multicore Systems (멀티코어 시스템에서 고성능 네트워크 I/O 가상화를 위한 프로세스 스케줄링)

  • Kim, Jong-Seo;Jin, Hyun-Wook
    • Proceedings of the Korean Information Science Society Conference
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    • 2011.06a
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    • pp.520-523
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    • 2011
  • 가상화는 하나의 컴퓨팅 노드에 여러 개의 가상 머신을 구성하여 서버의 자원 활용률을 높여주는 매우 유용한 기술이다. 하지만 아직까지 멀티코어 기반의 전가상화(Full Virtualization) 환경에서 네트워크 I/O 성능 향상을 위한 연구는 미비하다. 또한 기존의 프로세스 스케줄링 기법은 통신을 수행하는 게스트 도메인의 프로세스들을 효과적으로 지원해주지 않는다. 이러한 문제를 해결하기 위하여 네트워크 I/O 가상화를 위한 통신 프로세스의 동적 스케줄링 방식을 제안한다. 기존의 프로세스 친화도 결정 기법을 기반으로 네트워크 I/O 가상화에 특화된 제안 기법은 전가상화 VMM(Virtual Machine Monitor)인 VirtualBox를 대상으로 구현되었으며, 성능 측정을 통하여 네 개의 가상 머신을 적용하였을 경우 기존 리눅스 스케줄러 대비 총 네트워크 사용량을 약 97% 상승 시킴을 보인다.

Firewall System based on Network Traffic State (네트워크 트래픽 상태 기반의 방화벽 시스템)

  • Song, Byung-Wook;Kim, Hong-Chul;Park, In-Sung;Kim, Sang-Wook
    • Proceedings of the Korea Information Processing Society Conference
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    • 2001.04b
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    • pp.1077-1080
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    • 2001
  • 본 논문에서는 트래픽 상태를 기반으로 네트워크 패킷의 상호관계에 따라 트래픽을 제어하는 방화벽 모델을 제시한다. 기존의 방화벽은 단순한 필터링 메커니즘과 보안 정책으로 복잡하고 다양해진 네트워크 트래픽 패턴에 효과적으로 대응할 수 없었다. 그러나, 본 논문에서는 네트워크 트래픽의 정보를 정적인 상태 정보와 동적인 상태 정보로 구분하여 수집하고 이러한 정보를 보안 정책에 의하여 생성된 상태 그래프의 의사 결정에 반영함으로서 트래픽의 미세한 변화에도 효과적이고 다양한 대응을 할 수 있도록 하였다. 그리고, 트래픽 분석기, 네트워크 에이전트, 관리자 인터페이스로 구분함으로서 관리자 인터페이스의 형태와 위치의 독립성을 높임으로서 보다 효과적인 사용환경을 제공하도록 하였다.

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A Migration Method of Virtual Machines based Dynamic Threshold in Virtualization Environments (가상화 환경에서 동적 임계치 기반 가상 머신 이주 기법)

  • Choi, Hogun;Park, JiSu;Shon, Jin Gon
    • The Journal of Korean Association of Computer Education
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    • v.18 no.2
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    • pp.83-90
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    • 2015
  • In an virtualization environment, several virtual machines use physical resources together. If a specific virtual machine uses to much of the computing resources, other machines may not be working properly. There are various method to solve this problem. Most representative study is to migrate a specified virtual machines to a different server, a target server. In this study, server load can be transferred to a target server by the remigrate of the load imposed on virtual machine. It is still problematic that virtual machine has to remigrate to a different server. This thesis has proposed the algorithm determining the remigration targets by applying dynamic thresholds to solve those problems. The migration algorithm applies dynamic thresholds according to the following criteria. Firstly, the usage of CPU, network and memory; secondly, decide the set of artificial machine and the target server based on the resources surpassed thresholds; thirdly, determine artificial machines based on the resource usage in the target server.

TPC-BS: Transmission Power Control based on Binary Search in the Wireless Sensor Networks (TPC-BS: 센서 네트워크에서 이진검색 방법을 이용한 빠른 전송전력 결정 방법)

  • Oh, Seung-Hyun
    • Journal of Korea Multimedia Society
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    • v.14 no.11
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    • pp.1420-1430
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    • 2011
  • This paper proposes a new method to optimize energy consumption in a wireless modem by setting up a transmission power value according to the distance between nodes and circumstance in the MAC layer of IEEE 802.15.4. The proposed method can dynamically find an optimal transmission power range using the binary search scheme and minimize overhead caused by multiple message transmissions when determining the optimal transmission power. The determined transmission power is used for transmitting data packets and can be modified dynamically depending on the changes in a network environment when exchanging data packets and acknowledgement signals. The results of the simulations show 30% reduction in energy consumption while 2.5 times increase in data transmission rate per unit of energy comparing with IEEE 802.15.4 standard.

Dynamic Threshold Determination Method for Energy Efficient SEF using Fuzzy Logic in Wireless Sensor Networks (무선 센서 네트워크에서 통계적 여과 기법의 에너지 효율 향상을 위한 퍼지논리를 적용한 동적 경계값 결정 기법)

  • Choi, Hyeon-Myeong;Lee, Sun-Ho;Cho, Tae-Ho
    • Journal of the Korea Society for Simulation
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    • v.19 no.1
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    • pp.53-61
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    • 2010
  • In wireless sensor networks(WSNs) individual sensor nodes are subject to security compromises. An adversary can physically capture sensor nodes and obtain the security information. And the adversary injects false reports into the network using compromised nodes. If undetected, these false reports are forwarded to the base station. False reports injection attacks can not only result in false alarms but also depletion of the limited amount of energy in battery powered sensor nodes. To combat these false reports injection attacks, several filtering schemes have been proposed. The statistical en-routing filtering(SEF) scheme can detect and drop false reports during the forwarding process. In SEF, The number of the message authentication codes(threshold) is important for detecting false reports and saving energy. In this paper, we propose a dynamic threshold determination method for energy efficient SEF using fuzzy-logic in wireless sensor networks. The proposed method consider false reports rate and the number of compromised partitions. If low rate of false reports in the networks, the threshold should low. If high rate of false reports in networks, the threshold should high. We evaluated the proposed method’s performance via simulation.

Embracing Device Characteristics for Dynamic Adaptive Video Streaming (DLNA 기기 특성을 고려한 동적 적응형 스트리밍에 대한 연구)

  • Kim, Mijung;Jin, Feng;Yoon, Ilchul;Jin, Xianshu
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2014.05a
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    • pp.574-577
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    • 2014
  • Multimedia contents sharing services based on DLNA (Digital Living Network Alliance) technology such as Allshare or Smartshare in wireless home networks is widely adapted in Korea. However, the characteristics of the wireless network - frequently fluctuated bandwidth and signal strength could degrade the quality perceived by users. To minimize the impact of the challenge there are active researches in dynamic adaptive streaming. This paper proposes a dynamic adaptive streaming approach designed in a wireless network taking into account of the specifications of the user device such as resolution and processor. We modify the Kalman filter considering the characteristics of the device and demonstrate that the proposed approach determines Bit Rate using the modified filter.

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An Energy Efficient Clustering Scheme for WSNs (WSN에서 에너지 효율적인 클러스터링 기법)

  • Chung, Kil-Soo;Lee, Won-Seok;Song, ChangYoung
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.4
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    • pp.252-258
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    • 2013
  • As WSN is energy constraint so energy efficiency of nodes is important. Because avoiding long distance communication, clustering operating in rounds is an efficient algorithm for prolonging the lifetime of WSN and its performance depends on duration of a round. A short round time leads to frequent re-clustering while a long round time increases energy consume of cluster heads more. So existing clustering schemes determine proper round time, based on the parameters of initial WSN. But it is not appropriate to apply the round time according to initial value throughout the whole network time because WSN is very dynamic networks nodes can be added or vanished. In this paper we propose a new algorithm which calculates the round time relying on the alive node number to adapt the dynamic WSN. Simulation results validate the proposed algorithm has better performance in terms of energy consumption of nodes and loss rate of data.