• Title/Summary/Keyword: Information flow control

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A Study on Secure Role-Based Access Control (안전한 직무 기반 접근 제어에 대한 연구)

  • Lee, Ho
    • Journal of the Korea Society of Computer and Information
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    • v.6 no.4
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    • pp.119-124
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    • 2001
  • In the paper, is proposed a secure role-based access control model that not only has s functions such as security, integrity and flow control, but also can easily meet access requirements of role-based social organizations. The proposed role-based access control mod designed based on proven existing rule-based access control mechanisms in order to be app real access control systems. The model proposed in the paper is simple and secure. It can be used for the web-based application systems working on the Internet.

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A Study on the Dynamic Flow Control Algorithm on Video Conference System (화상회의 시스템에서 동적 흐름 제어기법에 관한 연구)

  • Koo Ha-Sung
    • Journal of Korea Society of Industrial Information Systems
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    • v.10 no.3
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    • pp.48-56
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    • 2005
  • This paper proposes a dynamic end-to-end flow control algorithm that is more effective than previous methods considering either the Rate of Packet Loss (RPL) or Round Trip Time (RTT). When the RPL is under normal conditions, the current network status will be in one of three defined states by using the RTT and this makes bandwidth control precise before serious packet loss occurs. If the RPL exceeds a critical level, then the network is considered to be in a fourth state. Suitable transmission rates are determined depending on the network status and are controlled by adjusting not only the number of transmitted frames but also the quality of the frames. In this paper, we present some experimental results of the proposed algorithm. According to our quantitative analysis, the proposed method performs 1.6 to 6 times better than the previous method in terms of the RPL. At the same time, the total number of transmitted packets is increased, which indicates that the proposed method can provide greater bandwidth capacity than previous methods.

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Prevention of Buffer Overflow in the Mobility Support Router for I-TCP (I-TCP를 위한 이동성 지원 라우터에서의 버퍼 오버플로우 방지)

  • 김창호;최학준;장주욱
    • Journal of KIISE:Information Networking
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    • v.31 no.1
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    • pp.20-26
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    • 2004
  • A congestion control algorithm to prevent buffer overflow in MSR(Mobility Support Router) for I-TCP is proposed. Due to high bit error rate and frequent hand-offs over wireless environment, the current congestion control scheme in TCP Reno over mixed(wired and wireless) network exhibits lower throughput than the throughput achieved over wired only network. I-TCP has been proposed to address this by splitting a TCP connection into two TCP connections over wired section and wireless section, respectively. However, buffer overflow in MSR may occur whenever there are excessive bit errors or frequent hand-offs. This may lead to the loss of packets acked by MSR(resident in buffer) to the sender, but not received by the receiver, breaking TCP end-to-end semantics. In this Paper, a new scheme is proposed to prevent the MSR buffer from overflow by introducing “flow control” between the sender and the MSR. Advertised window for the TCP connection between the sender and the MSR is tied to the remaining MSR buffer space, controlling the flow of packets to the MSR buffer before overflow occurs.

An Error Recovery Mechanism for Communications with Reliability and Transport Control for Media Access in Sensor Network (센서 네트워크에서의 매체제어를 위한 전송제어 및 신뢰성 있는 통신을 위한 에러 복구 기법)

  • Min, Byung-Ung;Kim, Dong-Il;Choi, Sam-Gil
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.11 no.6
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    • pp.1190-1194
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    • 2007
  • In sensor network, the importance of transporting data with reliability is growing gradually to support communications. Data flow from sink to nodes needs reliability for the control or management, that is very sensitive and intolerable, however relatively, data flow from nodes to sink is tolerable. In this paper, with emphasis of the data flow from sink to nodes, we proposed the mechanism that establishes confidence interval for transport. Establishing confidence interval herby-hop, not end to end, if errors happen or there's missing data, this mechanism recovers them with selective acknowledgement using fixed window. In addition, this mechanism supports franc congestion control depending on the buffer condition. Through the simulation, we showed that this mechanism has an excellent performance for error recovery in sensor network.

An ABR flow control algorithm considering propagation delay (ATM 망에서 전파 지연을 고려한 ABR 흐름 제어)

  • 박기현;김승천;김동연;이재용;이상배
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.35S no.5
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    • pp.17-26
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    • 1998
  • B-ISDN has many advantages to provide multimedia, image transfer, etc. Recently, ABR service has been proposed in order to satisfy user's various requirements in it. In this paper, we propose a new ABR flow control algorithm called CAPRO. This algorithm uses the buffer proportional to propagation delay and controls the traffic on a link-by-link basis in order to minimize the effect of propagation delay. In order to use buffer more efficienctly, we define the request cell and the control cell. Then, we analyze our algorithm using mathematical model, simulate it using SLAM system, and compare to the existing EPRCA. As a result, our algorithm has the benifit of the throughput, cell loss probability, and fairness.

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동축류 이차유동 분사를 이용한 추력 벡터 제어 방법에서 코안다 플랩의 형상에 따른 작동 특성 연구

  • Kim, Ju-Hyeon
    • Proceeding of EDISON Challenge
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    • 2016.03a
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    • pp.537-540
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    • 2016
  • 유체역학적 추력 방향 제어(Fluidic Thrust Vector Control) 방법 중 하나인 동축류 제어 유동 분사를 이용한 추력 방향 제어(Co-flow Thrust Vector Control)의 작동 특성에 대해서 연구하였다. 이 제어 방법은 점성 유동이 벽면에 부착되어 흐르는 코안다 효과(Coanda Effect)를 이용하여 주 유동을 편향 시키는 방법으로서 그 편향각은 이러한 제어 유동 노즐 출구의 플랩 형상에 영향을 받는 것으로 알려져 있다. 이 연구에서는 출구 플랩 형상을 여러 가지로 바꾸어 가며 주 유동의 전압력 300kPa일 때 제어 유동의 편향각이 포화되는 제어유동의 전압력을 측정하였다. 그 결과 쐐기형 플랩의 각도가 증가할수록 포화 영역에서의 편향각은 증가하며 그 각은 플랩의 각도와 일치한다. 그러나 각도가 증가할수록 제어 유동이 플랩의 벽면을 지나면서 팽창파에 의해 가속되어 충격파을 발생시키게 되고 이 충격파는 주 유동에게까지 전파되어 주 유동 제트의 속도를 감소시킨다.

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Real-Time Stochastic Optimum Control of Traffic Signals

  • Lee, Hee-Hyol
    • Journal of information and communication convergence engineering
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    • v.11 no.1
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    • pp.30-44
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    • 2013
  • Traffic congestion has become a serious problem with the recent exponential increase in the number of vehicles. In urban areas, almost all traffic congestion occurs at intersections. One of the ways to solve this problem is road expansion, but it is difficult to realize in urban areas because of the high cost and long construction period. In such cases, traffic signal control is a reasonable method for reducing traffic jams. In an actual situation, the traffic flow changes randomly and its randomness makes the control of traffic signals difficult. A prediction of traffic jams is, therefore, necessary and effective for reducing traffic jams. In addition, an autonomous distributed (stand-alone) point control of each traffic light individually is better than the wide and/or line control of traffic lights from the perspective of real-time control. This paper describes a stochastic optimum control of crossroads and multi-way traffic signals. First, a stochastic model of traffic flows and traffic jams is constructed by using a Bayesian network. Secondly, the probabilistic distributions of the traffic flows are estimated by using a cellular automaton, and then the probabilistic distributions of traffic jams are predicted. Thirdly, optimum traffic signals of crossroads and multi-way intersection are searched by using a modified particle swarm optimization algorithm to realize real-time traffic control. Finally, simulations are carried out to confirm the effectiveness of the real-time stochastic optimum control of traffic signals.

An Unload and Load Request Logic for Semiconductor Fab Considering Inter-Bay Material Flow (Inter-Bay 물류 흐름을 고려한 반도체 Fab의 Unload 및 Load Request Logic 개발)

  • Suh, Jung-Dae;Koo, Pyung-Hoi;Jang, Jae-Jin
    • IE interfaces
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    • v.17 no.spc
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    • pp.131-140
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    • 2004
  • The purpose of this paper is to develop and show the efficiency of the URL(Unload Request Logic) and LRL(Load Request Logic) of the dispatcher in the Fab(Fabrication) Manufacturing Execution System. These logics are the core procedures which control the material(wafer and glass substrate) flow efficiently in the semiconductor and LCD fab considering inter-bay as well as intra-bay material flow. We use the present and future status information of the system by look-ahead and the information about the future transportation schedule of Automated Guided Vehicles. The simulation results show that the URL and LRL presented in this paper reduce the average lead time, average and maximum WIP level, and the average available AGV waiting time.

The Mathematical Analysis of an Extended Mark Flow Graph for Design of the Discrete-event Control System (이산시스템 설계를 위한 확장된 마크흐름선도의 수학적 해석)

  • 김희정;백형구;김종민;여정모
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2001.05a
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    • pp.692-695
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    • 2001
  • The EMFG(Extended Mark Flow Graph) is not only a powerful tool to. designing the discrete-event system conceptually or specifically but also a good representation tool for implementing the system directly. We present a transitions-firing process and automatic changes of the number of marks in each box as a firing determination algorithm with the incident matrix and the state transition equation. The convenient analysis and design of a system as well as Computer Aided Design is possible because the operations of an EMFG ran be represented in the mathematical analysis with ease.

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Characteristics of Sediment Movement and Local Peoples' Countermeasure for Evacuation - focused on Inie areas of Kangwon-do - (집중 호우에 따른 부유토사 유출 특징 및 주민 대응 -2006넌 7월 강도 인제 지역을 중심으로-)

  • Kang, Sang-Hyeok
    • Spatial Information Research
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    • v.16 no.1
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    • pp.11-17
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    • 2008
  • In order to reduce flood damage with debris flow, it is necessary to build up comprehensive flood control, including structural and non-structural countermeasures. In this paper, the decision making factors of individual refuge activities which are major non-structural activities to save peoples, lives against flood have been estimated based on questionnaire survey. Furthermore, in order to effective debris flow countermeasures, its simulation has carried out and it will useful fur minimizing their damages.

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