• Title, Summary, Keyword: Congestion Prediction

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UDT Flow Control Method based on Congestion Prediction (혼잡예측 기반의 UDT 흐름제어 기법)

  • Lee, Seung-ah;Kim, Seunghae;Cho, Gihwan
    • Proceedings of the Korea Information Processing Society Conference
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    • pp.1019-1022
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    • 2010
  • 네트워크 기술의 발전으로 이용할 수 있는 대역폭이 증가하고 있다. 그에 따라 증가한 대역폭을 효율적으로 사용하기 위한 전송 기술이 요구되고 있다. TCP Vegas는 RTT(Round Trip Time)를 이용해 혼잡을 미리 예측하여 윈도우 크기를 조절하는 혼잡 제어 알고리즘을 사용한다. UDT는 높은 대역폭과 큰 RTT 환경에서 대용량 데이터를 전송하기 위해 제공된 응용 기반의 전송 프로토콜이다. 본 논문에서는 UDT에 혼잡예측 알고리즘을 적용한 새로운 UDT의 혼잡제어 알고리즘을 제안한다. 혼잡예측을 통해 혼잡한 구간, 혼잡하지 않은 구간을 나누어 혼잡윈도우를 갱신한다. 혼잡하지 않은 구간에서 혼잡윈도우를 증가시키고 혼잡한 구간에서 혼잡윈도우를 감소시킴으로써 기존의 UDT보다 성능이 개선되었음을 확인 할 수 있다.

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The Prediction of Rolling Contact Fatigue of Wheels for a Korea High Speed Train (한국형 고속철도 차량의 차륜의 구름접촉 피로 예측)

  • Choi Jeong Heum;Han Dong-Chul;Kim Ki-Hwan
    • Proceedings of the KSR Conference
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    • pp.1109-1114
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    • 2005
  • The rolling contact fatigue of wheels for high speed trains is a matter of increasing importance. The wheel damages from fatigue crack makes noise up and safety down. RCF-casued accidents cause traffic congestion and economical costs as well as personal injuries. In this study, we examine the rolling contact fatigue of wheels for power car running at 300km/h. Using the results of multi-body dynamic analysis and the proposed procedure of Ekberg, we calculate the fatigue index of surface-initiated fatigue, subsurface-initiated fatigue and fatigue initiated at deep material defects. As a result. the fatigue index shows us whether fatigue will appear and in which form. In addition, we present Shakedown map on surface-initiated fatigue.

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Prediction of Speed in Urban Freeway Having More Freight Vehicles - Based in I-696 in Michigan -

  • Kim, Tae-Gon;Jeong, Yeon-Woo
    • Journal of Navigation and Port Research
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    • v.36 no.7
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    • pp.591-597
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    • 2012
  • Generally an urban freeway means a primary arterial which provides road users with a free-flow speed, except for ramp junctions during rush hours. However, most road users suffer from traffic congestion in the basic segments as well as in the ramp junctions of urban freeway during rush hours, because most road users prefer urban freeways to local roads in the urban areas. This study then intends to analyze lane traffic characteristics of urban freeway basic segments having more freight vehicles during rush hours, find the lane showing a high correlation with the segment speed between lane speeds, and finally suggest a segment-speed predictive model by the lane speed of urban freeway basic segments during rush hours.

Highway traffic noise modeling and estimation based on vehicles volume and speed

  • Rassafi, Amir Abbas;Ghassempour, Jafar
    • Advances in environmental research
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    • v.4 no.4
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    • pp.211-218
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    • 2015
  • Traffic noise estimation models are useful in evaluation of the noise pollution in current circumstances. They are helpful tools for design and planning new roads and highways. Measurement of average traffic noise level is possible when traffic speed and volume are known. The objective of this study was to devise a model for prediction of highway traffic noise levels based on current traffic variables in Iran. The design of this model was to take the impact of traffic congestion into consideration and to be field tested. This study is a library research augmented by field study conducted on Saeedi Highway located south west of Tehran. The period for the field study lasted 5 days from 7-12 February, 2013. This study examined liner and non-liner methods in formulation of its model. Liner method without a fixed coefficient was the best fit for the intended model. The proposed model can serve as a decision making tool to estimate the impact of key influential factors on sound pressure levels in urban areas in Iran.

Dynamic Retry Adaptation Scheme to Improve Transmission of H.264 HD Video over 802.11 Peer-to-Peer Networks

  • Sinky, Mohammed;Lee, Ben;Lee, Tae-Wook;Kim, Chang-Gone;Shin, Jong-Keun
    • ETRI Journal
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    • v.37 no.6
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    • pp.1096-1107
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    • 2015
  • This paper presents a dynamic retry adaptation scheme for H.264 HD video, called DRAS.264, which dynamically adjusts the retry limits of frames at the medium access control (MAC) layer according to the impact those frames have on the streamed H.264 HD video. DRAS.264 is further improved with a bandwidth estimation technique, better prediction of packet delays, and expanded results covering multi-slice video. Our study is performed using the Open Evaluation Framework for Video Over Networks as a simulation environment for various congestion scenarios. Results show improvements in average peak signal-to-noise ratios of up to 4.45 dB for DRAS.264 in comparison to the default MAC layer operation. Furthermore, the ability of DRAS.264 to prioritize data of H.264 bitstreams reduces error propagation during video playback, leading to noticeable visual improvements.

A Prediction Model on Freeway Accident Duration using AFT Survival Analysis (AFT 생존분석 기법을 이용한 고속도로 교통사고 지속시간 예측모형)

  • Jeong, Yeon-Sik;Song, Sang-Gyu;Choe, Gi-Ju
    • Journal of Korean Society of Transportation
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    • v.25 no.5
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    • pp.135-148
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    • 2007
  • Understanding the relation between characteristics of an accident and its duration is crucial for the efficient response of accidents and the reduction of total delay caused by accidents. Thus the objective of this study is to model accident duration using an AFT metric model. Although the log-logistic and log-normal AFT models were selected based on the previous studies and statistical theory, the log-logistic model was better fitted. Since the AFT model is commonly used for the purpose of prediction, the estimated model can be also used for the prediction of duration on freeways as soon as the base accident information is reported. Therefore, the predicted information will be directly useful to make some decisions regarding the resources needed to clear accident and dispatch crews as well as will lead to less traffic congestion and much saving the injured.

Predicting Average Speed within the Enterance and Exit Ramp Junction Areas of Urban Freeway (도시고속도로의 진출·입 연결로 접속구간 내 평균속도의 추정에 관한 연구)

  • Kim, Tae Gon;Kwon, Mi Hyeon;Ji, Seung Keun
    • Journal of The Korean Society of Civil Engineers
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    • v.30 no.3D
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    • pp.215-222
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    • 2010
  • Average speed denotes a travel speed based on the average travel time of vehicles to traverse a segment of roadway, and average travel speed is used as a measure of effectiveness (MOE) suggested in the highway capacity manual (HCM) for evaluating the level of service (LOS) of roadway. Most of the urban freeways in our country are having congestion problem regardless of the rush hours as a high-speed highway with a speed limit of 80km/h or less. Especially traffic congestion within the ramp junction areas is becoming worse by the increased traffic and lack of links with the arterials around the urban freeway. So, the purpose in this study is to identify the traffic characteristics within the ramp junction areas of urban freeway, predict the average speed within the ramp junction areas based on the traffic characteristics identified, and finally prove the validity of the average speed predicted.

A Theoretical Analysis of Probabilistic DDHV Estimation Models (확률적인 중방향 설계시간 교통량 산정 모형에 관한 이론적 해석)

  • Cho, Jun-Han;Kim, Seong-Ho;Rho, Jeong-Hyun
    • Journal of Korean Society of Transportation
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    • v.26 no.3
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    • pp.199-209
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    • 2008
  • This paper is described the concepts and limitations for the traditional directional design hour volume estimation. The main objective of this paper is to establish an estimation method of probabilistic directional design hour volume in order to improve the limitation for the traditional approach method. To express the traffic congestion of specific road segment, this paper proposed the link travel time as the probability that the road capacity can accommodate a certain traffic demand at desired service level. Also, the link travel time threshold was derived from chance-constrained stochastic model. Such successive probabilistic process could determine optimal ranked design hour volume and directional design hour volume. Therefore, the probabilistic directional design hour volume can consider the traffic congestion and economic aspect in road planning and design stage. It is hoped that this study will provide a better understanding of various issues involved in the short term prediction of directional design hourly volume on different types of roads.

Strategies for Providing Detour Route Information and Traffic Flow Management for Flood Disasters (수해 재난 시 우회교통정보 제공 및 교통류 관리전략)

  • Sin, Seong-Il;Jo, Yong-Chan;Lee, Chang-Ju
    • Journal of Korean Society of Transportation
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    • v.25 no.6
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    • pp.33-42
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    • 2007
  • This research proposes strategies about providing detour route information and traffic management for flood disasters. Suggested strategies are based on prevention and preparation concepts including prediction, optimization, and simulation in order to minimize damage. Specifically, this study shows the possibility that average travel speed is increased by proper signal progression during downpours or heavy snowfalls. In addition, in order to protect the drivers and vehicles from dangerous situations, this study proposes a route guidance strategy based on variational inequalities such as flooding. However, other roads can have traffic congestion by the suggested strategies. Thus, this study also shows the possibility to solve traffic congestion of other roads in networks with emergency signal modes.

Development of a Freeway Travel Time Estimating and Forecasting Model using Traffic Volume (차량검지기 교통량 데이터를 이용한 고속도로 통행시간 추정 및 예측모형 개발에 관한 연구)

  • 오세창;김명하;백용현
    • Journal of Korean Society of Transportation
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    • v.21 no.5
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    • pp.83-95
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    • 2003
  • This study aims to develop travel time estimation and prediction models on the freeway using measurements from vehicle detectors. In this study, we established a travel time estimation model using traffic volume which is a principle factor of traffic flow changes by reviewing existing travel time estimation techniques. As a result of goodness of fit test. in the normal traffic condition over 70km/h, RMSEP(Root Mean Square Error Proportion) from travel speed is lower than the proposed model, but the proposed model produce more reliable travel times than the other one in the congestion. Therefore in cases of congestion the model uses the method of calculating the delay time from excess link volumes from the in- and outflow and the vehicle speeds from detectors in the traffic situation at a speed of over 70km/h. We also conducted short term prediction of Kalman Filtering to forecast traffic condition and more accurate travel times using statistical model The results of evaluation showed that the lag time occurred between predicted travel time and estimated travel time but the RMSEP values of predicted travel time to observations are as 1ow as that of estimation.