• 제목/요약/키워드: Traffic control

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항공교통관제사와 조종사 인적오류의 연계성 (Association of Human Error on Air Traffic Controller and Pilot)

  • 문우춘;최연철;양한모
    • 한국항공운항학회지
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    • 제16권4호
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    • pp.35-40
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    • 2008
  • There are many studies indicate that human is one of the major contributing factors to the aviation accident. To this end, the Human Factor of pilots and in flight operations has been a popular subject to be studied, however, not of the air traffic controllers. Recently, some States have started studying Human Errors in Air Traffic Control field, removal of the potential errors in advance and prevention of the similar errors. This study analyzed Human Errors in air traffic control in terms of LOSA of airlines, which has been actively studied. This study will contribute to safe Flight Operation and Air Traffic Control.

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도시고속도로 교통류 제어전략이 교통안전에 미치는 영향에 관한 연구 (A Study on the Effect of Urban Freeway Traffic Control Strategies on Safety)

  • 강정규
    • 대한교통학회지
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    • 제14권2호
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    • pp.223-237
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    • 1996
  • Based on the traffic and accident data collected on a 4.2km (2.6mile) section of Interstate highway 35W in Minneapolis the relationship between traffic operation variables and safety measures is investigated. An aggregate specification that could be integrated into an urban freeway safety prediction methodology is proposed as a multiple regression model. The specification includes lane occupancy and volume data, which are the control parameters commonly used because they can be measured in real time. The primary variables that appear to affect the safety of urban freeway are : vehicle-miles of travel, entrance ramp volumes and the dynamic effect of queue building. The potential benefits of freeway traffic control strategies on freeway safety are also investigated via a simulation study. It was concluded that improvement of urban freeway safety is achievable by traffic control strategies which homogenize traffic conditions areound critical occupancy values.

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현장적용을 위한 연동형 반감응 신호제어 개발 및 분석 (Developing and Evaluation of Coordinated Semi-Actuated Signal Control for Field Application)

  • 박순용;이석기;정준화
    • 한국콘텐츠학회논문지
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    • 제14권3호
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    • pp.451-462
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    • 2014
  • 본 연구에서는 지방부 간선 또는 지선 축에서 효과적으로 사용 가능한 연동형 반감응 신호제어 알고리즘을 개발하고 이를 평가하였다. 연동형 반감응 신호제어에 대한 모의실험 결과를 살펴보면, 주 부 도로의 교통량 차이가 커질수록 연동형 반감응 신호제어의 지체가 최적화된 고정식 신호제어에 비해 감소하는 것을 확인하였다. 그러나 주부도로의 교통량이 같거나 전체 교통량이 많아지면 최적화된 고정식 신호제어의 지체가 더 낮게 나타났으며, 횡단 보행량이 많아질수록 차량 지체가 증가하는 것으로 확인되었다. 따라서 연동형 반감응 신호제어는 차량 교통량이 일정수준 이하인 곳에 적용하되, 횡단 보행량을 고려하여 적용지역을 선별해야 할 것이다.

ABR 트랙픽 제어를 위한 버퍼 readout 스케쥴링 (A buffer readout scheduling for ABR traffic control)

  • 구창회;이재호
    • 전자공학회논문지S
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    • 제34S권11호
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    • pp.25-33
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    • 1997
  • The end-to-end rate-based control mechanism is used for the flow control of the ABR service to allow much more flexibility in ATM switching system. To accommodate the ABR service effciently many algorithms such as EFCI, EPRCA, ERICA, and CAPC2 have been proposed for the switch algorithm. ABR cells and related RM cells are received at the ATM switch fabric transparently without any processing. And then cells received from the traffic source are queued in the ABR buffer of switching system. The ABR buffer usually has some thresholds for easy congestion control signal transmission. Whatever we use, therefore, these can be many ABR traffic control algorithms to implement the ABR transfer capability. The genertion of congestion indicate signal for ABR control algorithms is determined by ABR buffer satus. And ABR buffer status is determined by ABR cells transfer ratio in ATM switch fabrics. In this paper, we presented the functional structures for control of the ABR traffic capability, proposed the readout scheduling, cell slot allocation of output link and the buffer allocation model for effective ABR traffic guranteeing with considering CBR/VBR traffics in ATM switch. Since the proposed readout scheduling scheme can provide more avaliable space to ABR buffer than existing readout scheduling scheme, generation rate of a SEND signal, that is, BCN signal in destination node can be increased for ABR call connection. Therefore, the proposed scheme, in this paper, can be appropriate as algorithm for effective ABR traffic service on output link of ATM switching node.

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ATM 망에 대한 트래픽 제어의 문제점 분석 (Traffic control issues for ATM networks)

  • 최영철;조유제;최문기
    • 한국통신학회:학술대회논문집
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    • 한국통신학회 1991년도 추계종합학술발표회논문집
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    • pp.179-182
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    • 1991
  • In this paper, we survey traffic control issues for the B-ISDN based on the ATM. We first investigate traffic descriptors to represent the characteristics of various ATM traffics in a standardized form. Also, we examine key issues related to the connection admission control, usage parameter control, network parameter control, priority control, and congestion control.

A New Class-Based Traffic Queue Management Algorithm in the Internet

  • Zhu, Ye
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제3권6호
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    • pp.575-596
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    • 2009
  • Facing limited network resources such as bandwidth and processing capability, the Internet will have congestion from time to time. In this paper, we propose a scheme to maximize the total utility offered by the network to the end user during congested times. We believe the only way to achieve our goal is to make the scheme application-aware, that is, to take advantage of the characteristics of the application. To make our scheme scalable, it is designed to be class-based. Traffic from applications with similar characteristics is classified into the same class. We adopted the RED queue management mechanism to adaptively control the traffic belonging to the same class. To achieve the optimal utility, the traffic belonging to different classes should be controlled differently. By adjusting link bandwidth assignments of different classes, the scheme can achieve the goal and adapt to the changes of dynamical incoming traffic. We use the control theoretical approach to analyze our scheme. In this paper, we focus on optimizing the control on two types of traffic flows: TCP and Simple UDP (SUDP, modeling audio or video applications based on UDP). We derive the differential equations to model the dynamics of SUDP traffic flows and drive stability conditions for the system with both SUDP and TCP traffic flows. In our study, we also find analytical results on the TCP traffic stable point are not accurate, so we derived new formulas on the TCP traffic stable point. We verified the proposed scheme with extensive NS2 simulations.

무선랜에서의 실시간 및 비실시간 트래픽 스케줄링 (Scheduling of Real-time and Nonreal-time Traffics in IEEE 802.11 Wireless LAN)

  • Lee, Ju-Hee;Lee, Chae Y.
    • 한국경영과학회지
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    • 제28권2호
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    • pp.75-89
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    • 2003
  • Media Access Control (MAC) Protocol in IEEE 802.11 Wireless LAN standard supports two types of services, synchronous and asynchronous. Synchronous real-time traffic is served by Point Coordination Function (PCF) that implements polling access method. Asynchronous nonreal-time traffic is provided by Distributed Coordination Function (DCF) based on Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol. Since real-time traffic is sensitive to delay, and nonreal-time traffic to error and throughput, proper traffic scheduling algorithm needs to be designed. But it is known that the standard IEEE 802.11 scheme is insufficient to serve real-time traffic. In this paper, real-time traffic scheduling and admission control algorithm is proposed. To satisfy the deadline violation probability of the real time traffic the downlink traffic is scheduled before the uplink by Earliest Due Date (EDD) rule. Admission of real-time connection is controlled to satisfy the minimum throughput of nonreal-time traffic which is estimated by exponential smoothing. Simulation is performed to have proper system capacity that satisfies the Quality of Service (QoS) requirement. Tradeoff between real-time and nonreal-time stations is demonstrated. The admission control and the EDD with downlink-first scheduling are illustrated to be effective for the real-time traffic in the wireless LAN.

ATM 망에서의 통화품질 평가를 위한 근사화 기법과 이를 이용한 호 수락 제어 (A call admission control in ATM networks using approximation technique for QOS estimation)

  • 안동명;한덕찬
    • 한국통신학회논문지
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    • 제23권9A호
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    • pp.2184-2196
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    • 1998
  • Admission control is one of the most important congestion control mechanism to be executed at the call set up phase by regulating traffic into a network in a preventive way. An efficient QOS evaluation or bandwidth estimation method is required for call admission to be decided in real time. In this paper, we spropose a computtionally simple approximation method of estimating cell loss probability and mean cell delay for admission control of both delay sensitive and loss sensitive calls. Mixed input queueing system, where a new call combines with the existing traffic, is used as a queueing model for QOS estimation. Also traffic parameters are suggested to characterize both a new call and existing traffic. Aggregate traffic is approximated by a renewal process with these traffic parameters and then mean delay and cell loss probability are detemined using appropriate approximation formulas. The accuracy of this approximation approach is examined by comparing their results with exact analysis or simulation results of vrious mixed unput queueing systems. Based on this QOS estimation method, call admission control scheme which is traffic independent and computable in yeal time are proposed.

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시간지연에 따른 열차의 운행간격 제어알고리즘 (Traffic Regulation Algorithm for Metro Lines with Time Delay)

  • 박민기
    • 전기전자학회논문지
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    • 제26권4호
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    • pp.590-595
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    • 2022
  • 철도운행 시스템에서 외란에 의해 지연이 발생하면 열차 사이의 시간간격 편차가 증가하여 열차운행이 불안정하게 된다. 따라서 이러한 불안정한 열차운행을 방지하기 위하여 열차의 운행간격을 제어하는 것이 필요하다. 본 논문에서는 철도운행 시스템의 안정성을 보장하는 간단하면서도 효과적인 새로운 열차의 운행간격 제어알고리즘을 제안한다. 제안한 알고리즘은 이산 열차모델에 기반하며 열차의 적정한 운행간격이 유지되도록 출발시간 편차와 선행열차 제어입력의 선형조합에 의해 운행시간을 제어한다. 시뮬레이션을 통해 제안한 방법의 유효성을 보인다.

STOP AND GO CRUISE CONTROL

  • Venhovens, P.;Naab, K.;Adiprasito. B.
    • International Journal of Automotive Technology
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    • 제1권2호
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    • pp.61-69
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    • 2000
  • This paper will address the basic requirements for realizing a stop and go cruise control system. Issues discussed comprise: functional, sensor and basic HMI requirements, primary characterization of naturalistic stop & go driving, and the basic approach of the transformation of situational knowledge in an elementary controller.

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