• Title/Summary/Keyword: Information flow control

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An Interior Point Method based Reactive Optimal Power Flow Incorporating Margin Enhancement Constraints

  • Song Hwa-Chang;Lee Byong-Jun;Moon Young-Hwan
    • KIEE International Transactions on Power Engineering
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    • v.5A no.2
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    • pp.152-158
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    • 2005
  • This paper describes a reactive optimal power flow incorporating margin enhancement constraints. Margin sensitivity at a steady-state voltage instability point is calculated using invariant space parametric sensitivity, and it can provide valuable information for selection of effective control parameters. However, the weakest buses in neighboring regions have high margin sensitivities within a certain range. Hence, the control determination using only the sensitivity information might cause violation of operational limits of the base operating point, at which the control is applied to enhance voltage stability margin in the direction of parameter increase. This paper applies an interior point method (IPM) to solve the optimal power flow formulation with the margin enhancement constraints, and shunt capacitances are mainly considered as control variables. In addition, nonlinearity of margin enhancement with respect to control of shunt capacitance is considered for speed-up control determination in the numerical example using the IEEE 118-bus test system.

Priority-based Scheduling Policy for OpenFlow Control Plane

  • Kasabai, Piyawad;Djemame, Karim;Puangpronpitag, Somnuk
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.2
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    • pp.733-750
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    • 2019
  • Software Defined Networking (SDN) is a new network paradigm, allowing administrators to manage networks through central controllers by separating control plane from data plane. So, one or more controllers must locate outside switches. However, this separation may cause delay problems between controllers and switches. In this paper, we therefore propose a Priority-based Scheduling policy for OpenFlow (PSO) to reduce the delay of some significant traffic. Our PSO is based on packet prioritization mechanisms in both OpenFlow switches and controllers. In addition, we have prototyped and experimented on PSO using a network simulator (ns-3). From the experimental results, PSO has demonstrated low delay for targeted traffic in the out-of-brand control network. The targeted traffic can acquire forwarding rules with lower delay under network congestion in control links (with normalized load > 0.8), comparing to traditional OpenFlow. Furthermore, PSO is helpful in the in-band control network to prioritize OpenFlow messages over data packets.

Proposed Distribution Voltage Control Method for Connected Cluster PV Systems

  • Lee, Kyung-Soo;Yamaguchi, Kenichiro;Kurokawa, Kosuke
    • Journal of Power Electronics
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    • v.7 no.4
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    • pp.286-293
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    • 2007
  • This paper proposes a distribution voltage control method when a voltage increase condition occurs due to reverse power flow from the clustered photovoltaic (PV) system. This proposed distribution voltage control is performed a by distribution-unified power flow controller (D-UPFC). D-UPFC consists of a hi-directional ac-ac converter and transformer. It does not use any energy storage component or rectifier circuit, but it directly converts ac to ac. The distribution model and D-UPFC voltage control using the ATP-EMTP program were simulated and the results show the voltage increase control in the distribution system.

CPN Management Model and Network Access Flow/Congestion Control in ATM Network (CPN의 관리 모델과 망 엑세스 흐름/혼잡 제어)

  • 김양섭;권혁인;김영찬
    • 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.

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FuzzyGuard: A DDoS attack prevention extension in software-defined wireless sensor networks

  • Huang, Meigen;Yu, Bin
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.7
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    • pp.3671-3689
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    • 2019
  • Software defined networking brings unique security risks such as control plane saturation attack while enhancing the performance of wireless sensor networks. The attack is a new type of distributed denial of service (DDoS) attack, which is easy to launch. However, it is difficult to detect and hard to defend. In response to this, the attack threat model is discussed firstly, and then a DDoS attack prevention extension, called FuzzyGuard, is proposed. In FuzzyGuard, a control network with both the protection of data flow and the convergence of attack flow is constructed in the data plane by using the idea of independent routing control flow. Then, the attack detection is implemented by fuzzy inference method to output the current security state of the network. Different probabilistic suppression modes are adopted subsequently to deal with the attack flow to cost-effectively reduce the impact of the attack on the network. The prototype is implemented on SDN-WISE and the simulation experiment is carried out. The evaluation results show that FuzzyGuard could effectively protect the normal forwarding of data flow in the attacked state and has a good defensive effect on the control plane saturation attack with lower resource requirements.

Performance Comparison between Material Flow Control Mechanisms Using Simulation (시뮬레이션을 통한 생산흐름통제시스템의 성능비교)

  • Park, Sang-Geun;Ha, Chung-Hun
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.35 no.1
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    • pp.115-123
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    • 2012
  • Material flow control mechanism is a kind of operational policy in manufacturing. It is very important because it varies throughput, throughput time, and work-in-process (WIP) under the same manufacturing resources. Many Researchers have developed various material flow control mechanisms and insisted that their mechanism is superior to others. However the experimental environment used in the performance comparison are different and impractical. In this paper, we set various manufacturing environments to fairly compare five previous material flow control mechanism : Push, Pull, CONWIP, Gated MaxWIP, and Critical WIP Loops. The simulation results show that the Push is superior to others in both of throughput and WIP if required demand is less than 80% of capacity. In addition, the performance of CONWIP and its variants are not different statistically.

Control of Boundary Layer Flow Transition via Distributed Reduced-Order Controller

  • Lee, Keun-Hyoung
    • Journal of Mechanical Science and Technology
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    • v.16 no.12
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    • pp.1561-1575
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    • 2002
  • A reduced-order linear feedback controller, which is used to control the linear disturbance in two-dimensional plane Poiseuille flow, is applied to a boundary layer flow for stability control. Using model reduction and linear-quadratic-Gaussian/loop-transfer-recovery control synthesis, a distributed controller is designed from the linearized two-dimensional Navier-Stokes equations. This reduced-order controller, requiring only the wall-shear information, is shown to effectively suppress the linear disturbance in boundary layer flow under the uncertainty of Reynolds number. The controller also suppresses the nonlinear disturbance in the boundary layer flow, which would lead to unstable flow regime without control. The flow is relaminarized in the long run. Other effects of the controller on the flow are also discussed.

Underwater Packet Flow Control for Underwater Networks (수중네트워크를 위한 수중패킷 흐름제어기법)

  • Shin, Soo Young;Park, Soo Hyun
    • Journal of Korea Multimedia Society
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    • v.19 no.5
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    • pp.924-931
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    • 2016
  • In this paper, Various network adaptive MAC scheduling technique is proposed to effectively overcome limits of narrow bandwidth and low transmission speed in underwater. UPFC(Underwater Packet Flow Control) is a technique to reduce both the number of transmission and transmission time using three types (Normal, Blocked, Parallel) of data transmission. In this technique, the load information, in which a transmission node have, is transmitted to destination node using marginal bit in reserved header. Then the transmitted information is referred to determine weighting factor. According to the weighting factor, scheduling is dynamically changed adaptively. The performance of UPFC is analyzed and flow control technique which can be applied to Cluster Based Network and Ad Hoc network as well.

A Translation Method from Control Flow Descriptions in cycle-accurate level to Synthesizable RTL VHDL Descriptions (Cycle 수준의 Control Flow Description에서 합성 가능한 VHDL 기술로의 변환 방법에 관한 연구)

  • 윤창열;장경선
    • Proceedings of the IEEK Conference
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    • 2003.07b
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    • pp.819-822
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    • 2003
  • This paper defines an algorithmic description language in cycle-accurate level which can be used to design hardware components. The proposed language is less complex and more flexible than VHDL language. In that the language includes C-like control flow descriptions and brief timing information(i.e. clock cycle boundaries) indicated by 'wait_edge' statements. We generate RTL VHDL codes from the descriptions. The proposed language requires only 10~30% of the # of lines to describe the same functionality compared with RTL VHDL.

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