• 대한수학회지
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• 제57권4호
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• pp.987-1004
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• 2020

Motivated by the traffic flow model with Arrhenius looka-head relaxation dynamics introduced in [25], this paper proposes a traffic flow model with look ahead relaxation-behind intensification by inserting look behind intensification dynamics to the flux. Finite time shock formation conditions in the proposed model with various types of interaction potentials are identified. Several numerical experiments are performed in order to demonstrate the performance of the modified model. It is observed that, comparing to other well-known macroscopic traffic flow models, the model equipped with look ahead relaxation-behind intensification has both enhanced dispersive and smoothing effects.

• 한국ITS학회 논문지
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• 제8권2호
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• pp.60-66
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• 2009

Acceleration Noise는 교통류의 안정성을 진단하는데 중요한 지표이다. 하지만, 기존의 연구에서는 개별차량의 Acceleration Noise에 대해서만 수행되었고, 거시적 관점에서의 Acceleration Noise에 대해서는 연구가 이루어지지 않은 실정이다. 본 논문에서는 거시적 교통류 모니터링 지표인 Network Acceleration Noise를 제안하고, 이를 분석하여 거시 교통류 모니터링 활용방안에 대한 연구를 수행하였다.

• 대한교통학회지
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• 제14권1호
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• pp.101-116
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• 1996

Increased attention has been paid in recent years to the need of traffic management for alleviating urban traffic congestion. This paper presents a discrete event modeling and simulation framework for analyzing the traffic flow. Traffic simulation models can be classified as being either microscopic and macroscopic models. The discrete event modeling and simulation technique can be basically employed to describe the macroscopic traffic simulation model. To do this, we have employed the System Entity Structure/Model Base (SES/MB) framework which integrates the dynamic-based formalism of simulation with the symbolic formalism of AI. The SES/MB framework supports to hierarchical, modular discrete event modeling and simulation environment. We also adopt the Symbolic DEVS (Discrete Event System Specification) to developed the automated analysis methodology for generating optimal signal light policy. Several simulation tests will demonstrates the techniques.

• 한국ITS학회 논문지
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• 제9권2호
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• pp.33-40
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• 2010

본 논문에서는 거시교통류 모니터링을 위한 세 가지 지표를 다루고 신뢰성 있는 지표산출에 필요한 적정 프로브차량 비율을 결정하기 위해 샘플링 기법을 이용하는 방법에 대하여 연구한다. 모니터링 세 가지 지표로는 Travel Time Index(TTI), Acceleration Noise(AN) 그리고 Two Fluid(TF)를 살펴보고, 적정 프로브 차량 비율의 결정방법으로는 절대오차를 이용한 표본크기의 결정방법과 상대오차를 이용한 표본크기의 결정방법에 대하여 고찰한다. 그리고 표본추출비율에 따른 지표 값 변동을 비교 검토하기 위해 서울시 강남지역의 대규모 자료를 이용하여 모의실험을 실시하였다. 모의실험 결과 교통수요 단계(Demand Level)가 증가함에 따라 상대오차를 이용한 표본 추출비율이 줄어들며, 추출비율은 허용오차, 링크통과차량의 수와 반비례 관계이므로 추출비율을 증가시킬수록 허용오차를 줄일 수 있음을 알 수 있었다.

• 한국도로학회논문집
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• 제18권1호
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• pp.119-129
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• 2016

PURPOSES : The purpose of this study is to develop a methodology for estimating additional carbon emissions due to freeway incidents. METHODS : As our country grows, our highway policy has mainly neglected the environmental and social sectors. However, with the formation of a national green growth keynote and an increase in the number of people interested in environmental and social issues, problems related to social issues, such as traffic accidents and congestion, and environmental issues, such as the impact of air pollution caused by exhaust gases that are emitted from highway vehicles, are beginning to be discussed. Accordingly, studies have been conducted on a variety of environmental aspects in the field of road transport, and for the quantitative calculation of greenhouse gas emissions, using various methods. However, in order to observe the effects of carbon emissions, microscopic simulations must use many difficult variables such as cost, analysis time, and ease of analysis process. In this study, additional greenhouse gas emissions that occur because of highway traffic accidents were classified by type (incident handling time, number of lanes blocked, freeway level of service), and the annual additional emissions based on incidents were calculated. According to the results, congestion length and emissions tend to increase with an increase in incident clearance time, number of occupied lanes, and worsening level of service. Using this data, we analyzed accident data on the Gyeong-bu Expressway (Yang-Jae IC - Osan IC) for a year. RESULTS : Additional greenhouse gas emissions that occur because of highway traffic accidents were classified by type (incident handling time, number of lanes blocked, freeway level of service) and annual additional emissions caused by accidents were calculated. CONCLUSIONS : In this study, a methodology for estimating carbon emissions due to freeway incidents was developed that incorporates macroscopic flow models. The results of the study are organized in the form of a look-Up table that calculates carbon emissions rather easily.

• 대한교통학회지
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• 제22권3호
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• pp.179-201
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• 2004

지능형 교통체계(intelligent transport systems)의 구축이 점차 널리 확대됨에 따라 교통류의 실시간 모형화(online traffic flow modeling)의 중요성이 증대되고 있다. 교통량-밀도 관계는 주어진 교통량, 밀도 상황에서 교통류의 행태를 나타낼 뿐만 아니라 거시 교통류 모형의 결과에 많은 영향을 미친다. 현재까지 교통량-밀도관계에 관한 대부분의 연구는 그 관계식을 규명하는데 그치고 있다. 상류부와 하류부의 교통 상태에 따른 교통량-밀도관계의 시간적 변화는 교통류의 모형화에 반드시 고려되어야 할 특성이지만, 현재까지 그에 대한 연구가 폭넓게 이루어지지 않고 있는 실정이다. 본 논문에서는 한 지점에서의 교통량-밀도관계가 시간의 흐름에 따라 분석되었고 states diagram으로 표현되었다. 동적 교통량-밀도관계 (dynamic flow-density relation)는 states diagram으로부터 fuzzy-logic을 이용하여 유추되었고, 거시 교통류모형을 실시간으로 응용할 수 있는 기초를 제공하였다. 동적 교통량-밀도관계를 거시 교통류 모형에 이용함으로써 교통류의 실시간 모형화 과정에서 발생하는 모수추정 (parameter calibration) 문제를 완화하였다.

• 대한교통학회지
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• 제27권1호
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• pp.27-34
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• 2009

도로교통망의 시스템변화에 대한 효과분석의 일환으로 1979년 Herman이 제시한 Two-Fluid Model을 적용하여 거시적인 교통류 변화특성을 분석하였으며, 이를 통해 도로시설의 운영개선 효과를 정량적으로 확인하였다. 본 연구에서는 일반국도 3호선 의정부 전체 구간의 약 8km, 총 31개 신호교차로를 분석 대상으로 하며, TSIS CORSIM 및 Run Time Extension을 이용한 미시적 시뮬레이션 분석으로 현황 및 개선 대안에 대한 개별차량의 주행정보를 추출하였다. Two-Fluid Model의 파라메타 산출결과 현황 대비 신호제어시스템 개선 시 네트워크의 서비스 질을 의미하는 단위거리 당 평균최소통행시간(Tm)은 약 35% 감소하였으며, 네트워크 수요증가에 대한 저항성을 의미하는 파라메타 n은 약 28%의 향상된 결과를 나타내었다. 국도 축을 대상으로 하는 시뮬레이션 기반의 자료 수집으로 인해 제한된 연구결과이나 Two-Fluid Model이 신호 최적화 및 연동형 반감응제어의 적용 등 신호제어시스템 개선에 대한 우수한 거시적 효과평가 지표로 활용되어 질 수 있음을 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권10호
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• pp.3858-3874
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• 2021

As an essential part of the urban transportation system, precise perception of the traffic flow parameters at the traffic signal intersection ensures traffic safety and fully improves the intersection's capacity. Traditional detection methods of road traffic flow parameter can be divided into the micro and the macro. The microscopic detection methods include geomagnetic induction coil technology, aerial detection technology based on the unmanned aerial vehicles (UAV) and camera video detection technology based on the fixed scene. The macroscopic detection methods include floating car data analysis technology. All the above methods have their advantages and disadvantages. Recently, indoor location methods based on wireless signals have attracted wide attention due to their applicability and low cost. This paper extends the wireless signal indoor location method to the outdoor intersection scene for traffic flow parameter estimation. In this paper, the detection scene is constructed at the intersection based on the received signal strength indication (RSSI) ranging technology extracted from the wireless signal. We extracted the RSSI data from the wireless signals sent to the road side unit (RSU) by the vehicle nodes, calibrated the RSSI ranging model, and finally obtained the traffic flow parameters of the intersection entrance road. We measured the average speed of traffic flow through multiple simulation experiments, the trajectory of traffic flow, and the spatiotemporal map at a single intersection inlet. Finally, we obtained the queue length of the inlet lane at the intersection. The simulation results of the experiment show that the RSSI ranging positioning method based on wireless signals can accurately estimate the traffic flow parameters at the intersection, which also provides a foundation for accurately estimating the traffic flow state in the future era of the Internet of Vehicles.

• Journal of Electrical Engineering and Technology
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• 제12권5호
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• pp.2031-2042
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• 2017

In this paper, a novel traffic flow control method based-on ramp metering and speed regulation using an adaptive sliding mode control (ASMC) method along with a deadzoned parameter adaptation law is proposed at a stochastic macroscopic level traffic environment, where the influence of the density and speed disturbances is accounted for in the traffic dynamic equations. The goal of this paper is to design a local traffic flow controller using both ramp metering and speed regulation based on ASMC, in order to achieve the desired density and speed for the maintenance of the maximum mainline throughput against disturbances in practice. The proposed method is advantageous in that it can improve the traffic flow performance compared to the traditional methods using only ramp metering, even in the presence of ramp storage limitation and disturbances. Moreover, a prior knowledge of disturbance magnitude is not required in the process of designing the controller unlike the conventional sliding mode controller. A stability analysis is presented to show that the traffic system under the proposed traffic flow control method is guaranteed to be uniformly bounded and its ultimate bound can be adjusted to be sufficiently small in terms of deadzone. The validity of the proposed method is demonstrated under different traffic situations (i.e., different initial traffic status), in the sense that the proposed control method is capable of stabilizing traffic flow better than the previously well-known Asservissement Lineaire d'Entree Autoroutiere (ALINEA) strategy and also feedback linearization control (FLC) method.

• 한국ITS학회:학술대회논문집
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• 한국ITS학회 2010년도 춘계학술대회
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• pp.126-131
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• 2010