• 디지털산업정보학회논문지
• /
• 제18권2호
• /
• pp.9-16
• /
• 2022

The nodes constituting the vehicle ad hoc network (VANET) are vehicles moving along the road and road side units (RSUs) installed around the road. The vehicle ad hoc network is used to collect the status, speed, and location information of vehicles driving on the road, and to communicate with vehicles, vehicles, and RSUs. Today, as the number of vehicles continues to increase, urban roads are suffering from traffic jams, which cause various problems such as time, fuel, and the environment. In this paper, we propose a method to solve traffic congestion problems on urban roads and demonstrate that the method can be applied to solve traffic congestion problems through performance evaluation using two typical protocols of vehicle ad hoc networks, AODV and GPSR. The performance evaluation used ns-2 simulator, and the average number of traffic jams and the waiting time due to the average traffic congestion were measured. Through this, we demonstrate that the vehicle ad hoc-based traffic congestion management technique proposed in this paper can be applied to urban roads in smart cities.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• 제1권1호
• /
• pp.1-5
• /
• 2001

In this paper, we propose a fuzzy traffic controller that is able to cope with traffic congestion appropriately. In order to consider such situation as loss of green time caused by spillback of upper crossroad, it imports a degree of traffic congestion of upper roads which vehicles on a crossroad are to proceed to. We constructed the equal-partitioned fuzzy traffic controller that uses the membership functions of the same size and shape, and modified the size and shape, and modified the size and shape of its membership functions by the membership function modification algorithm. In experiment, we compared and analyzed the fixed signal controller, the fuzzy traffic controller with the membership of the same size and shape, and the modified fuzzy traffic controller by using the delay time, the proportion of entered vehicles to occurred vehicles and the proportion of passed vehicles to entered vehicles. As a result of experiment, the modified fuzzy controller showed more enhanced performance than others.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제12권3호
• /
• pp.1152-1167
• /
• 2018

In this paper, I propose an application layer cooperative congestion control scheme for safety message broadcast in vehicular networks, called CMS, that adaptively controls a vehicle's safety message rate and transmit timing based on the channel congestion state. Motivated by the fact that all vehicles should transmit and receive an application layer safety message in a periodic manner, I directly exploit the message itself as a means of estimating the channel congestion state. In particular, vehicles can determine wider network conditions by appending their local channel estimation result onto safety message transmissions and sharing them with each other. In result CMS realizes cooperative congestion control without any modification of the existing MAC protocol. I present extensive NS-3 simulation results which show that CMS outperforms conventional congestion control schemes in terms of the packet collision rate and throughput, especially in a high-density traffic environment.

• 전기전자학회논문지
• /
• 제21권2호
• /
• pp.115-122
• /
• 2017

In vehicular safety service, every vehicle broadcasts Basic Safety Message (BSM) periodically to inform neighbor vehicles of host vehicle information. However, this can cause network congestion in a region that is crowded with vehicles resulting in a reduction in the message delivery ratio and an increase in the end-to-end delay. Therefore, it could destabilize the vehicular safety service system. In this paper, in order to improve the congestion control and to consider the hidden node problem, we propose a congestion control scheme using entire network congestion level estimation combined with transmission power control, data rate control and time slot based transmission control algorithm. The performance of this scheme is evaluated using a Qualnet network simulator. The simulation result shows that our scheme mitigates network congestion in heavy traffic cases and enhances network capacity in light traffic cases, so that packet error rate is perfectly within 10% and entire network load level is maintained within 60~70%. Thus, it can be concluded that the proposed congestion control scheme has quite good performance.

• 전기학회논문지
• /
• 제64권11호
• /
• pp.1578-1586
• /
• 2015

Personal rapid transit (PRT) is getting attention as a new form of transportation. It is energy efficient and provides the high level of passenger service. In this study, the dynamic PRT dispatching and routing problem is dealt with. Passengers request transportation service on a complex network, and an operating system monitors passenger arrivals and coordinates vehicles in real time. A new online dispatching and routing algorithm is proposed, which minimizes the total travel distance of vehicles and the waiting time of passengers. The algorithm dispatches vehicles by considering multiple vehicles' state and multiple passengers at the same time. In particular, finding the shortest-time path is attempted by taking into account the future congestion on lanes. Discrete-event simulation is employed to validate the performance of the proposed algorithm. The results show the algorithm in this study outperforms others.

• 대한교통학회지
• /
• 제29권6호
• /
• pp.17-23
• /
• 2011

$CO_2$ 배출량은 차량의 속도와 관련이 있으며. 속도는 도로의 종류에 따라 다르게 나타난다. 그러므로 단속류 간선 도로의 차량 당 $CO_2$ 배출량은 교차로 특성과 지정체의 영향을 받을 가능성이 많다. 따라서 교차로의 존재, 지정체의 영향과 차량 당 $CO_2$ 배출량의 분석이 필요하다. 연구 방법은 첫째, 국도를 대상으로 차량의 교차로 통과방법에 따른 차량 당 $CO_2$ 배출량차이를 비교하였다. 둘째, 전체 대상구간에서 자유속도와 지정체 속도에 따른 차량 당 $CO_2$ 배출량차이를 비교하였다. 셋째, 구간별 차량당 $CO_2$ 배출량차이를 비교하였다. 차량 당 $CO_2$ 배출의 정량화를 위하여 속도에 따른 배출량 곡선을 사용하였다. 연구 결과는 첫째, 교차로에서 감가속 방법에 따라 최대 12%까지 차량 당 $CO_2$ 배출량의 차이가 나타났다. 둘째, 대상 구간 전체에서 지정체로 인해 30%이상 차량 당 $CO_2$를 배출하는 것으로 나타났다. 셋째, 구간별 비교 결과 교차로 특성 등에 따라 최대 차량 당 40%까지 차이가 나타났다. 본 연구를 통해 교차로 통과방법, 통행속도, 교차로 특성을 개선하면 차량 당 $CO_2$ 배출량을 감소할 수 있다는 추론이 가능하다.

• 한국ITS학회 논문지
• /
• 제12권6호
• /
• pp.68-77
• /
• 2013

본 연구에서는 끼어들기 위반단속시스템 개발을 위한 교통정체판정방법에 대한 실험적 연구결과를 제시하였다. 해당 정체판정 방법은 정체를 검지하여 끼어들기 위반단속시스템의 최적 구동기준을 결정하는데 목적이 있다. ITS 분야에서 일반적으로 정체판정은 구간통행속도를 기준으로 한다. 그러나 영상검지 방식적용 시 속도오차 등으로 인해 정체판정의 오류가 높게 나타날 수 있으며, 본 연구에서는 현장실험을 통해 속도와 점유율을 종합적으로 고려한 방식을 제시하였다. 현장실험 결과 영상검지체계 기반의 끼어들기위반 단속시스템에서 정체판정 기준으로 속도의 경우 20km/h, 점유율의 경우 60% 이상의 조건을 적용할 경우 실제 정체상황과 같은 결과를 얻을 수 있었고, 정확도를 높일 수 있었다.

• 한국경영과학회지
• /
• 제41권3호
• /
• pp.75-96
• /
• 2016

This paper investigates the usefulness of drones in an urban delivery system. We define the vehicle and drone routing problem with time window (VDRPTW) and present a model that can describe a dual mode delivery system consisting of drones and vehicles in the metropolitan area. Drones are relatively free from traffic congestion but have limited flight range and capacity. Vehicles are not free from traffic congestion, and the complexity of urban road network reduces the efficiency of vehicles. Using drones and vehicles together can reduce inefficiency of the urban delivery system because of their complementary cooperation. In this paper, we assume that drones operate in a point-to-point manner between the depot and customers, and that customers in the need of fast delivery are willing to pay additional charges. For the experiment datasets, we use instances of Solomon (1987), which are well known in the Vehicle Routing Problem society. Moreover, to mirror the urban logistics demand trend, customers who want fast delivery are added to the Solomon's instances. We propose a hybrid evolutionary algorithm for solving VDRPTW. The experiment results provide different useful insights according to the geographical distributions of customers. In the instances where customers are randomly located and in instances where some customers are randomly located while others form some clusters, the dual mode delivery system displays lower total cost and higher customer satisfaction. In instances with clustered customers, the dual mode delivery system exhibits narrow competition for the total cost with the delivery system that uses only vehicles. In this case, using drones and vehicles together can reduce the level of dissatisfaction of customers who take their cargo over the time-window. From the view point of strategic flexibility, the dual mode delivery system appears to be more interesting. In meeting the objective of maximizing customer satisfaction, the use of drones and vehicles incurs less cost and requires fewer resources.

• 한국ITS학회 논문지
• /
• 제16권6호
• /
• pp.244-257
• /
• 2017

교통혼잡은 운전자의 인지반응시간, 운전미숙, 무리한 차로변경 등 인적요인으로부터 발생된다. 자율주행자동차가 도입되면 이러한 인적요인들이 배제되고 군집주행으로 인해 평균주행속도 상승, 교통흐름 안정화, 도로용량 증대 효과가 예상된다. 본 연구는 자율주행자동차도입으로 인한 교통흐름 변화를 교통량-밀도-속도 산포도 그래프를 통해 분석하고, 도로용량 증대 효과를 도출하였다. 분석 결과, 자율주행자동차의 혼입율이 높아질수록 교통량-밀도-속도의 그래프 곡선이 완화되며, 폭이 줄어들어 교통류가 안정적으로 변화하였다. 또한 자율주행자동차 혼입율 100%에서는 도로용량이 약 120% 증대되는 것으로 분석되었다. 자율주행자동차 도입으로 인한 교통혼잡개선 및 교통수요관리 측면에서 긍정적인 기대효과가 있을 것으로 분석되었다.

• 한국터널지하공간학회 논문집
• /
• 제18권1호
• /
• pp.41-52
• /
• 2016

터널 화재시 정체차량에 의한 정체길이가 터널연장을 초과할 경우, 환기저항의 증가에 따른 제연설비 용량의 증가가 발생하게 된다. 그러나 현행 방재지침에는 정체길이에 대한 정의가 없기 때문에 합리적 산출식의 제시가 필요하다. 본 연구에서는 터널 화재시 정체차량 대수에 의한 정체길이의 산정식을 제시하고, 터널연장별 적용성 분석을 수행하였다. 일반적인 터널의 경우, 화재시 정체길이의 과도한 적용을 방지하기 위해서는 터널연장 1,200 m 까지는 정체길이와 터널연장과의 상호비교가 필요한 것으로 분석되었고, 모델터널에 대한 적용성 평가결과 제연용 제트팬의 절감효과가 있는 것으로 분석되었다. 더불어 정체길이의 판별여부를 대형차혼입률과 터널연장의 관계로 설명할 수 있는 정량화 선도를 제시하였다. 결과적으로 제연설비 용량결정시, 정체차량에 의한 정체길이가 터널연장을 초과하는 경우에는 터널연장을 초과하는 차량대수는 차량에 의한 환기저항 산정에서 제외하는 것이 타당한 것으로 분석된다.