• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.6
• /
• pp.296-301
• /
• 2020

Three types of traffic signal systems are two-color signal systems that flash red and green and are mainly used on crosswalks, next, three-color equalization systems mainly used at T-shaped intersections with red and yellow lights and a green arrow, and third, four-color intersections that generally have red, yellow and green colored lights and a green arrow. In what is known as the "dilemma zone" area, a driver collects information that influences his/her decision whether to stop, speed, tail, interrupt, or violate a traffic light, depending on the intersection width, vehicle speed, cognitive response time and reference yellow signal time. This study examined the impact of changes in the length of the dilemma zone areas based on changes in yellow signal times, the speed of the intersection passages, and signal lamps. Downward adjustments of 50km/h and 60km/h affected yellow signal time. The yellow signal time increased by 0.1 to 2.3[s] due to this effect and the dilemma zone area increased by 1.22 to 26[m]. The driver of the dilemma zone could quickly decide to reduce the time remaining of the straight (3color, 4color) green signal to reduce the potential of a traffic accident at the intersection traffic. Safe entry of red (LED palm) and left-turn signals for entering flashed at the intersection and operated at midnight.

• Journal of Korean Society of Transportation
• /
• v.32 no.4
• /
• pp.410-420
• /
• 2014

This research suggests a new tram signal priority model which determines signal timings and tram intersection waiting time using analytical method. This model can calculate the signal timings for Early Green and Green Extension among the active tram signal priority techniques by tram detection time of upstream detector. Moreover, it can determine the tram intersection waiting time that means tram intersection travel time delay from a vantage point of tram travel. Under the active tram signal priority condition, priority phases can bring additional green time from variable green time of non-priority phases. In this study, the signal timing and tram intersection waiting time calculation model was set up using analytical methods. In case studies using an isolated intersection, this study checks tram intersection waiting time ranged 12.7 to 29.4 seconds when variable green times of non-priority phases are 44 to 10 seconds under 120 seconds of cycle length.

• Journal of Korean Society of Transportation
• /
• v.27 no.2
• /
• pp.15-22
• /
• 2009

There exist some limits when we forecast urban railway demand by traditional 4 step model. The first reason is that the model based on socioeconomic data by an administrative unit, 'Dong', yields a 'Dong' unit trip matrix. But a 'Dong' often has two or more stations. The second reason is that urban railway demand by station would be affected rather by station access area on foot than by a 'Dong' unit. So the model based on 'Dong' characteristic data have some inaccuracies in itself. Owing to the limits of the model based on 'Dong' unit data, there exits some difficulty in forecasting urban railway demand by station. So this paper studied two alternatives. The first is to forecast the demand by using the data of station access area on foot rather than 'Dong' unit data. This needs too much time and effort to collect data and analyse them, while the accuracy of the model didn't improve a lot. The second is to adjust the location of 'Dong' centroid and the length of centroid connector link. By this way we can reflect the characteristics of station access area on foot under traditional 4 step model. Comparing the expected demand to the observed data for each station, the result looks like very similar.

• Korean Chemical Engineering Research
• /
• v.52 no.4
• /
• pp.475-480
• /
• 2014

In the fields of researches associated with plant layout optimization, the main goal is to minimize the costs of pipelines for connecting equipment. However, what is the lacking of considerations in previous researches is to handle the multi floor processes considering the safety distances for domino impacts on a complex plant. The mathematical programming formulation can be transformed into MILP (Mixed Integer Linear Programming) problems as considering safety distances, maintenance spaces, and economic benefits for solving the multi-floor plant layout problem. The objective function of this problem is to minimize piping costs connecting facilities in the process. However, it is really hard to solve this problem due to complex unequality or equality constraints such as sufficient spaces for the maintenance and passages, meaning that there are many conditional statements in the objective function. Thus, it is impossible to solve this problem with conventional optimization solvers using the derivatives of objective function. In this study, the PSO (Particle Swarm Optimization) technique, which is one of the representative sampling approaches, is employed to find the optimal solution considering various constraints. The EO (Ethylene Oxide) plant is illustrated to verify the efficacy of the proposed method.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.12 no.4
• /
• pp.131-140
• /
• 2012

The shortest path search algorithm of navigation is generally based on Dijkstra algorithm and considers only the distance using the weight. Dijkstra algorithm based on the distance mainly ought to perform the 'number of nodes 1' and requires a lot of memory, for it is to start from the starting node and to decide the shortest path for all the nodes. Also, it searches only the same identical path in case of any bottleneck due to an accident nearby, since it is based only on the distance, and hence does not have a system that searches the detour road. In order to solve this problem, this paper considers only the travelling time per road (travelling speed * distance), without applying speed criteria (smoothness, slow speed, stagnation and accident control) or road class (express road, national road and provincial road). This provides an advantage of searching the detour, considering the reality that there are differences in time take for the car to travel on different roads with same distance, due to any accident, stagnation, or repair construction. The suggested algorithm proves that it can help us to reach the destination within the shortest time, making a detour from any congested road (outbreak) on providing an information on traveling time continuously(real-time) even though there is an accident in a particular road.

• Journal of Korean Society of Steel Construction
• /
• v.9 no.3 s.32
• /
• pp.287-300
• /
• 1997

In this study, an effective application method of AE technique for the detection of fatigue crack in multi-girder steel bridges has been proposed. The applicability has been examined through the laboratory works with bridge model. The proposed analytical method which evaluates the remaining fatigue lives of structural members may improve the rational determination of the priority of inspection for structural members assuming to have fatigue cracks. Laboratory tests for the application of AE technique to steel girder bridges show that the frequency bands of traffic noise are in the range between 10 show that the frequency bands of traffic noise are in the range between 100~200 kHz and the AE signal raised from fatigue cracks is concentrated around 400~500 kHz. Therefore. R30 sensor is proved to be the most suitable for the detection of cracks in steel girder bridges. A linear proportionality between the crack propagation and the frequency of AE signals has been obtained. In addition, an economic and effective source location method for steel girder bridges was studied through experiments.

• Journal of the Korea Institute of Building Construction
• /
• v.17 no.5
• /
• pp.445-451
• /
• 2017

Because of the supply-demand problem of aggregate, recently, the construction sites using 100% crushed sand are increasing and the use of low quality aggregate such as farmland sand is increasing too. When the low quality aggregate is used, the various quality defect of concrete such as the strength reduction, the increase of shrinkage and bleeding can be occurred. Therefore, in this study, the performance improvement PC admixture was developed to minimize the quality defect of plain concrete of basement parking area, when the low quality aggregate was used at the plain concrete of basement parking area. The slump loss to elapsed time test, the compressive strength test, the bleeding test and the drying shrinkage test were carried out.

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