• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.5
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• pp.29-37
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• 2017

Intersection signal's phase time is calculated and determined by car and pedestrian traffic volume. If signal phase time and traffic volume dis-matched, cars and pedestrians have much delay time. This paper suggested an All-Red phase application method that cars and pedestrians securing safety and minimizing traffic signal waiting time. The key solution of this suggested method is determining All-Red phase operation by using sum of spare green time that have no passing cars. That is, total time of spare green time that have no passing cars is longer than All-Red phase time, operating All-Red phase has an effect. And case study carried out at the signalized intersection, revealed that this suggested method has much effectiveness.

• Journal of Korean Society of Transportation
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• v.25 no.2 s.95
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• pp.83-93
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• 2007

Pedestrians and vehicle users should be treated with equal importance in urban street design. However, current street design suggests that the design criteria for sidewalks is based on the functional hierarchy of the vehicles, therefore it is necessary to develop sidewalk design standards that give more weight to pedestrians rather than vehicles. For this, this study suggests that the level of service of pedestrians should be considered in the process of designing sidewalks. Currently, level of service (LOS) criteria for pedestrians in the Korean Highway Capacity Manual are based on pedestrian volume, but the volume of pedestrians is seldomly estimated in practice. So, the current LOS criteria has limitations in terms of practical use. Also, the study assumes that the pedestrian flow rate is hardly the dominant factor that could affect the LOS of pedestrians at most urban sidewalks. In this context, the study considers a new LOS for sidewalk design based on the comfort of pedestrians while passing pedestrians coming from the opposite direction. Then the study attempts to link the new LOS criteria to the land use patterns using data of pedestrian traffic characteristics acquired from the field. In addition to this, the scope in which the suggested criteria can be applied is suggested.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.6
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• pp.133-143
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• 2018

Roundabouts are generally installed at which traffic and pedestrian volume is relatively small intersections, and hence traffic can flow one direction around a circular island without traffic lights. A number of researches for roundabout signal metering have been processing ways to deal with operation efficiency drops in conditions of unusual traffic and pedestrian volume increases. However, there is still a shortcoming exists in previous operation algorithm does not consider the hidden vehicles between yield lines and detectors and queueing vehicles in circular lanes. These queueing vehicles between them can be cleared by introducing the queue clearance time. The purpose of this research is developing a real time signal metering operation algorithm by considering the vehicle queue clearance time. The results of varying queue clearance time application show that there is a substantial average vehicle delay reduction in VISSIM Com-Interface simulation. When the total number of entering vehicle is 3,200~4,800 vehicle/hour with varying queue clearance time application 21~50 seconds gives average delay reduction per vehicle by 16.1~71.7%.

• Journal of Korean Society of Transportation
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• v.33 no.4
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• pp.337-347
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• 2015

Since the application of roundabouts by 2010 have been started, more than 350 roundabouts were installed in Korea. Recently the types of constructed roundabouts become various, and the intersection conditions for installing roundabouts were also various. However, there were some difficulties to install roundabouts around school zone due to safety problems. In this study, appropriate distance from adjacent signal crosswalks to roundabouts were estimated for securing pedestrian safety and operation efficiency around school zone. With the analyses, the minimum distance standard was suggested to obtain operational effectiveness of roundabout according to traffic volume, traffic flow, pedestrian green time and secures pedestrian safety and convenience. In this paper, average delay of roundabout as various length of distances between an adjacent crosswalk and a roundabout as different pedestrian signal times, traffic volumes, traffic flow rates were analyzed. Through this study, it was found that about four times of delay in a roundabout was generated if there was adjacent signal crosswalk. However if there is enough distance between an adjacent crosswalk and a roundabout, the value of increasing delay on roundabouts with adjacent a signalized crosswalk can be considerably reduced. Critical value of the distance between a roundabout and a signal crosswalk in case of roundabouts within 200-500 vehicle/hour/lane entry traffic flow, 20-40% of left turn traffic, and over 15 seconds pedestrian green time was about 50 meters. In conclusion, if there is minimum 40 meter distance from roundabouts, adjacent signal crosswalks can be installed and operated for students' safety around school zone.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.6
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• pp.54-63
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• 2014

Traffic accident frequency and severity level in Korea are known to be very serious. Especially the number of pedestrian fatalities was much worse and 1.6 time higher than the OECD average. According to the National Police Agency, the flash signals are reported to have many safety benefits as well as travel time reduction, which is opposed to the foreign studies. With this background of expanding the flash signal, this research aims to investigate the overall impact of the flash signal operation on safety, investigating and comparing the accident occurrence on the flash signal and the full signal intersections. For doing this accident prediction models for both flash and full signal intersections were estimated using independent variables (geometric features and traffic volume) and 3-year (2011-2013) accident data collected in Seoul. Considering the rare and random nature of accident occurrence and overdispersion (variance > mean) of the data, the negative binomial regression model was applied. As a result, installing wider crosswalk and increasing the number of pedestrian push buttons seemed to increase the safety of the flash signal intersections. In addition, the result showed that the average accident occurrence at the flash signal intersections was higher than at the full signal-operated intersections, 9% higher with everything else the same.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.3
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• pp.94-104
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• 2016

In this study, factor and cluster analysis are used to classify characteristics of the administrative basic unit, "Dong", of the Incheon Metropolitan City. Travel characteristics of the classified groups are then analyzed through databases to provide directions of urban transportation planning. First, industrially developed administrative-dong show a high commuting volume by using cars. Thus the analysis indicated the need to staggering work-hour system and signal operating system policy. Second, commercially developed administrative-dong show heavy use of public transportation and long distance commute as well as high volume of shoppers. The analysis indicated the need to improve road infrastructure. Third, densely populated administrative-dong show a high rate of commute to work and school as well as long hours of commuting. Thus the analysis indicated the need to improve road transportation policies during rush hours. Fourth, administrative-dong with multiple characteristics feature heavy pedestrian traffic thus the study analyzed the need to improve pedestrian environment policies. Lastly, administrative-dong in close proximity to train stations feature extensive use of biking as well as high volume of shoppers and students commuting. Thus the study analyzed the necessity to have plans to enhance accessibility.

• International Journal of Highway Engineering
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• v.20 no.2
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• pp.75-85
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• 2018

PURPOSES : This study aimed to analyze traffic accidents at circular intersections, and discuss accident reduction strategies based on land use and vehicle type. METHODS : Traffic accident data from 2010 to 2014 were collected from the "traffic accident analysis system" (TAAS) data set of the Road Traffic Authority. To develop the accident rate model, a multiple linear regression model was used. Explanatory variables such as geometry and traffic volume were used to develop the models. RESULTS : The main results of the study are as follows. First, it was found that the null hypotheses that land use and vehicle type do not affect the accident rate should be rejected. Second, 16 accident rate models, which are statistically significant (with high $R^2$ values), were developed. Finally, the area of the central island, number of speed humps, entry lane width, circulatory roadway width, bus stops, and pedestrian crossings were analyzed to determine their effect on accidents according to the type of land use and vehicle. CONCLUSIONS : Through the developed accident rate models, it was revealed that the accident factors at circular intersections changed depending on land use and vehicle type. Thus, selecting the appropriate location of bus stops for trucks, widening entry lanes for cars, and installing splitter islands and optimal lighting for motorcycles were determined to be important for reducing the accident rate. Additionally, the evaluation showed that commercial and mixed land use had a weaker effect on accidents than residential land use.

• International Journal of Highway Engineering
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• v.15 no.2
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• pp.131-138
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• 2013

PURPOSES : The intents of the study are to identify the accident factors and to demonstrate the potentials of tobit model as a tool to study the number of accidents on arterial roads segments. METHODS : This paper uses a tobit regression as a methodology to analyze the factors affecting the number of accidents. In pursuing the above goal, this study gives particular attentions to analyzing the data of 2,446 accidents (1,610 in major arterial roads and 836 in minor arterial roads) occurred on arterial roads in 2007 to 2010. RESULTS : First, 3 accident models which were classified by total arterial roads, major arterial roads and minor arterial roads, and were all statistically significant were developed. Second, the exclusive right-turn lane as common variable, and the number of accident, traffic volume, number of lanes, link length, rate of median, number of entrances, number of pedestrian crossings, number of curves, number of bus stops and exclusive left-turn as specific variables of the models were selected. Finally, the paired sample t-test could not be rejected the null hypotheses of three types of models. CONCLUSIONS : Using data from vehicle accidents on arterial roads, the estimation results show that many factors related to roadway geometrics and traffic characteristics significantly affect to the number of accidents.

• The Korean Journal of Ceramics
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• v.4 no.4
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• pp.368-371
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• 1998

The work aims to evaluate the necessary physical properties of Abrasion Resistant Pavers designed for high volume pedestrian and road vehicle traffic and their influence on the selection of raw materials and ceramic processes. The pavers' specifications such as high strength and ware resistance demand a careful clay preparation, slow drying, slow firing and a balanced chemical and mineralogical composition. Therefore, developing abrasion Resistant Pavers in existing modern brickmaking plants, which are designed primarily for making bricks and pavers for domestic applications, has become a challenge for manufacturers and ceramic professionals. The significance of quality control and research and development in the production of these high class pavers is also emphasised in this work through the investigation of a paver that exhibits shrinkage cracking.

• International Journal of Highway Engineering
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• v.17 no.4
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• pp.89-98
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• 2015

PURPOSES : This study evaluated the feasibility of implementing protected-permissive left-turn (PPLT) signals at three-leg signalized intersections. METHODS: A three-leg signalized intersection with permissive left-turn was first selected. A VISSIM simulation model was constructed using data collected from the test site. The VISSIM network was calibrated by adjusting related parameter values in order to minimize the difference between the simulated and surveyed critical gap. The calibrated network was validated by the number of waiting left-turning vehicles per cycle. Finally, the mobility and safety measures were extracted from simulation runs in which permissive, protected left turns as well as PPLTs were realized based on diverse traffic volume scenarios. RESULTS : The mobility-related measures of effectiveness (MOEs) of the case with PPLT outperformed the other two left-turn treatment scenarios. In particular, the average waiting time per cycle for the left-turn vehicles in the case with PPLT was reduced by 30 s. The safety-related MOEs of the case with PPLT were somewhat higher than those in the case with protected left-turns and much higher than those in the case with permissive left-turns. CONCLUSIONS : Based on the mobility- and safety-related MOEs generated from the VISSIM simulation runs, the use of PPLT seems to be feasible at three-leg signalized intersections where the left-turn is permissive and a pedestrian signal exists at the conflicting approach. However, in order to use the PPLT in earnest, it is necessary to revise the road traffic act, traffic signs, and related manuals.