• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.2
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• pp.63-75
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• 2013

Roundabouts have been operated in Europe, America and Australia since the 1970s, and many relevant researches continually was carried out. Though many studies regarding roundabout have been recently conducted in korea, most of them have focused on its operational safety and efficiency. Moreover, roundabout design guideline did not define a clear criteria related to pedestrian in roundabout, but seldom investigate the influences of pedestrian on crosswalk. In this study, we seek ways to operate the pedestrian crosswalk signal on roundabout maximizing their operational effects in exceptional case such as rush hour or intersection near the special facilities. We proved that roundabout signal operation is effective under certain circumstances in according to the number of pedestrian, and suggested the optimal signal timing plan for signalized roundabouts. For pursuing the above, we conducted the simulation test using the VISSIM model. The results show that the operational effectiveness of signalized roundabout was evaluated to be better than non-signalized roundabout in specific pedestrian volume condition. In addition, those results are confirmed using simulation analysis conducted on the real roundabout.

• Journal of the Korea Concrete Institute
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• v.28 no.5
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• pp.509-517
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• 2016

In terms of bridge construction, the concrete deck slab is weak members compared to beam members of the bridge supports. Deck slabs must be sound to support and distribute vehicle loads. If slabs are not enough to support the loads, it should be replaced. Bridge deck replacement has been an important industry over the world since the construction is simplified to shorten construction time and to save construction costs. Slab module provides a quickly, easily and reliably construction method in order to avoid high cost and minimum traffic disruption. in addition, slab module shows high reliability since they are factory products. However, slab module should be considered in the performance under various loads. In this study, structural analysis is performed to evaluate the performance of slab module under vehicle loads and temperature loads. Spiral rebar is also utilized around the vertical joints to improve the structural integrity under the lifting loads. In order to confirm the weak area of slab module for the lift condition, numerical analysis has been performed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5D
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• pp.617-625
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• 2008

In low-density areas where travel pattern is widely dispersed and travel demand is relatively low, transit operators find it very difficult to provide a reasonable level of service at a reasonable cost. Timed-transfer system or network, if designed properly, can provide a reasonable level of service for passengers using transit systems serving low-density areas. The paper intends to apply a timed-transfer system for bus lines serving Yangsan City area and to assess the effects resulted from the application. The concept of a timed-transfer network/system is briefly described, and the present conditions of bus systems in Yangsan City area are discussed, focusing on the aspects of network type and the related problems. The bus timed-transfer network for the area is then developed by adjusting the existing routes and network with the consideration of travel time, route alignments, headways and transfer centers. One must note that developing a timed-transfer network presumes that network and schedule should be developed together. The effects of the developed time-transfer system on the passengers and operators are found substantially so as to justify its introduction to the City. The results of this study will be of considerable use for planners to design the transit systems in low density areas, where in general travel activities are widely dispersed and travel demands are low, so that provision of good quality of transit services are difficult.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.4
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• pp.54-62
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• 2018

As a part of realization of artificial intelligence signal(AI Signal), this study proposed an actuated signal algorithm based on vehicle queue length that estimates in real time by deep learning. In order to implement the algorithm, we built an API(COM Interface) to control the micro traffic simulator Vissim in the tensorflow that implements the deep learning model. In Vissim, when the link travel time and the traffic volume collected by signal cycle are transferred to the tensorflow, the vehicle queue length is estimated by the deep learning model. The signal time is calculated based on the vehicle queue length, and the simulation is performed by adjusting the signaling inside Vissim. The algorithm developed in this study is analyzed that the vehicle delay is reduced by about 5% compared to the current TOD mode. It is applied to only one intersection in the network and its effect is limited. Future study is proposed to expand the space such as corridor control or network control using this algorithm.

• Journal of Korean Society of Transportation
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• v.22 no.1 s.72
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• pp.43-62
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• 2004

Conventionally the estimation method of the origin-destination Matrix has been developed by implementing the expansion of sampled data obtained from roadside interview and household travel survey. In the survey process, the bigger the sample size is, the higher the level of limitation, due to taking time for an error test for a cost and a time. Estimating the O-D matrix from observed traffic count data has been applied as methods of over-coming this limitation, and a gradient model is known as one of the most popular techniques. However, in case of the gradient model, although it may be capable of minimizing the error between the observed and estimated traffic volumes, a prior O-D matrix structure cannot maintained exactly. That is to say, unwanted changes may be occurred. For this reason, this study adopts a conjugate gradient algorithm to take into account two factors: estimation of the O-D matrix from the conjugate gradient algorithm while reflecting the prior O-D matrix structure maintained. This development of the O-D matrix estimation model is to minimize the error between observed and estimated traffic volumes. This study validates the model using the simple network, and then applies it to a large scale network. There are several findings through the tests. First, as the consequence of consistency, it is apparent that the upper level of this model plays a key role by the internal relationship with lower level. Secondly, as the respect of estimation precision, the estimation error is lied within the tolerance interval. Furthermore, the structure of the estimated O-D matrix has not changed too much, and even still has conserved some attributes.

• Journal of Korean Society of Transportation
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• v.20 no.5
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• pp.113-130
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• 2002

In this paper, we developed DNL(Dynamic Network Loading) model based on Moving cell theory to analyze the dynamic characteristics of traffic flow in congested network. In this paper vehicles entered into link at same interval would construct one cell, and the cells moved according to Cell following rule. In the past researches relating to DNL model a continuous single link is separated into two sections such as running section and queuing section to describe physical queue so that various dynamic states generated in real link are only simplified by running and queuing state. However, the approach has some difficulties in simulating various dynamic flow characteristics. To overcome these problems, we present Moving cell theory which is developed by combining Car following theory and Lagrangian method mainly using for the analysis of air pollutants dispersion. In Moving cell theory platoons are represented by cells and each cell is processed by Cell following theory. This type of simulation model is firstly presented by Cremer et al(1999). However they did not develop merging and diverging model because their model was applied to basic freeway section. Moreover they set the number of vehicles which can be included in one cell in one interval so this formulation cant apply to signalized intersection in urban network. To solve these difficulties we develop new approach using Moving cell theory and simulate traffic flow dynamics continuously by movement and state transition of the cells. The developed model are played on simple network including merging and diverging section and it shows improved abilities to describe flow dynamics comparing past DNL models.

• Journal of Korean Society of Transportation
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• v.30 no.4
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• pp.43-59
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• 2012

Assuming a completed Smart Highway road & communication environment that allows real-time information collection and transmission of road traffic condition ahead, the purpose of this study is to develop a plan for inducing a network-level safe driving pattern by providing road traffic condition and safety information to multiple drivers through a road information provision device. In this study, the device with a function that displays different colors according to the hazard level to the existing delineator has been named 'Smart Delineator'. Smart Delineator is a device that provides not only alignment information but also safety information for drivers to receive real-time warning information and intuitively recognize road traffic condition ahead so that drivers can respond. To examine the effects of safety driving inducement level on drivers, a simulation test was conducted using driving simulator as well as a satisfaction survey. The result showed that the Smart Delineator was able to identify the location of occurrence and affecting driving according pattern, either adhering to recommended speed or reducing speed according to the pre-defined hazard level.

• Journal of Preventive Medicine and Public Health
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• v.6 no.1
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• pp.43-49
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• 1973

In this study noise source in a ward at four general hospitals in Seoul area has been investigated and analysed. The degree of reaction against noise by 171 randomly has also been examined. The results of the study have shown that the source of noise is the speakers of wired broadcasting or from visiting guests in two hospitals located in residential area. The patients at the two other hospitals located at commercial site have been suffered more from traffic noise. However, because of their separated living at hospital from their ordinary houselife, sixty one percent of the inpatients have wished a music sound of around 60 dB (A). After having considered the results of the investigation and wishes of the inpatients, following suggestions have been made: 1. Reduce the number of guests or their length of stay. 2. Wired broadcasting system should be substitued by wireless one, or if it's unavoidable, it should be used in office rooms only. 3. Since the stops and starts of vehicles induce much noise, Seoul City Government be requested to prepare an appropriate administrative measure for the vehicles around hospital area and it should prevent the establishment of new hospitals along high way site. 4. By using earphone, inpatients can choose a wireless channel according to each individual's taste. This through the masking effect, would cover up the noise source. 5. Rooms along the streets should be utilized as offices, otherwise double windows should be set up for inpatient's wards.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.3
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• pp.1-19
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• 2021

The domastic hard shoulder running(HSR) System has been gradually expanding since its initial implementation in September 2007 with the aim of increasing capacity and resolving congestion. Hard Shoulder is used as a space for driver's visual comfort and a place for vehicles to evacuate in case of emergency, but it is replaced by a space for driving when the HSR System is implemented. Therefore, it was intended to determine the improvement effect before and after implementation of the HSR system through safety analysis and mobility analysis. The safety analysis analyzed the impact of traffic accidents by comparing HSR sections and similar sections. The mobility analysis was to determine the improvement effect by quantifying the speed and traffic volume changes before and after HSR System implementation. According to safety yanalysis, there is no effect of reducing traffic accidents when implementing the HSR System. In mobility analysis, the implementation of the HSR System significantly improved the speed of traffic during peak hours and significantly reduces slow and delay hours.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.1
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• pp.276-290
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• 2023

Several efforts in Korea are currently underway with the goal of commercializing autonomous vehicles. Hence, various studies are emerging on autonomous vehicles that drive safely and quickly according to operating guidelines. The current study examines the path search of an autonomous vehicle from a microscopic viewpoint and tries to prove the efficiency required by learning the lane change of an autonomous vehicle through Deep Q-Learning. A SUMO was used to achieve this purpose. The scenario was set to start with a random lane at the starting point and make a right turn through a lane change to the third lane at the destination. As a result of the study, the analysis was divided into simulation-based lane change and simulation-based lane change applied with Deep Q-Learning. The average traffic speed was improved by about 40% in the case of simulation with Deep Q-Learning applied, compared to the case without application, and the average waiting time was reduced by about 2 seconds and the average queue length by about 2.3 vehicles.