• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.1
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• pp.105-115
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• 2014

A numerical analysis on the smoke behavior and evacuee safety has been performed with computational fluid dynamics. The purpose of this study is to build computational processes for an evacuation and prevention of a fire disaster of a 3 km-length tunnel in Korea. To save computational cost, 1.5 km of the tunnel that can include a few cross-passing tunnels is considered. We are going to assess the fire safety in a road tunnel according to the smoke level, which consists of the smoke density and the height from the floor. The smoke density is obtained in detail from three-dimensional unsteady CFD analysis. To obtain proper temperature distributions on the tunnel wall, one-dimensional conduction equation is considered instead of an adiabatic wall boundary or a constant heat flux. The tunnel considered in this study equips the cross passing tunnels for evacuees every 250 m. The distance is critical in both safety and economy. The more cross passing tunnels, the more safe but the more expensive. Three different jet fan operations can be considered in this study; under- and over-critical velocities for normal traffic condition and 0-velocoty operation for the traffic congestion. The SE (smoke environment) level maps show a smoke environment and an evacuating behavior every moment.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.2
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• pp.164-181
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• 2023

In a low speed limit environment, the speed limit tolerance of automated traffic enforcement devices is very high, which is one of the main factors for the low compliance rate. Therefore, in this study, we aimed to the improve the speed limit tolerance and to present a new standard. The effects of the operator and user errors that can cause speeding by drivers were analyzed. Based on the results of the analysis, an improvement of the tolerance was proposed by applying an error in the enforcement device and GPS speed. In addition, long-term expected safety effects such as the accident rate and severity were estimated from the operator's perspective when improving the tolerance. As a result of the estimation, the speed limit compliance rate, accident rate, and change rate of a number of severe accidents due to speed change, and pedestrian traffic accident mortality rate were all improved in all speed limit environments. The introduction of the proposed improvement is expected to improve road safety significantly.

• Journal of Korean Society of Transportation
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• v.32 no.3
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• pp.266-279
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• 2014

For the evaluation of roadway safety, diverse methods, including before-after studies, simple comparison using historic traffic accident data, methods based on experts' opinion or literature, have been applied. Especially, many research efforts have developed traffic accident prediction models in order to identify critical elements causing accidents and evaluate the level of safety. A traffic accident prediction model must secure predictability and transferability. By acquiring the predictability, the model can increase the accuracy in predicting the frequency of accidents qualitatively and quantitatively. By guaranteeing the transferability, the model can be used for other locations with acceptable accuracy. To this end, traffic accident prediction models using non-linear regression, artificial neural network, and structural equation were developed in this study. The predictability and transferability of three models were compared using a model development data set collected from 90 signalized intersections and a model validation data set from other 33 signalized intersections based on mean absolute deviation and mean squared prediction error. As a result of the comparison using the model development data set, the artificial neural network showed the highest predictability. However, the non-linear regression model was found out to be most appropriate in the comparison using the model validation data set. Conclusively, the artificial neural network has a strong ability in representing the relationship between the frequency of traffic accidents and traffic and road design elements. However, the predictability of the artificial neural network significantly decreased when the artificial neural network was applied to a new data which was not used in the model developing.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.31-42
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• 2019

Among the driving information recorded in the event data recorder (EDR), the speed information of the vehicle before the traffic accident is a very important factor that determines the punishment of the driver of the accident vehicle, the identification of the offender and the victim, and the possibility of avoiding the accident. Also, by analyzing the EDR data, the deceleration of the accident vehicle can be analyzed. In this study, the results of the braking test of the previous study and the analysis of the EDR data of the traffic accident vehicle were compared to suggest an appropriate deceleration value applicable to the calculation of the stopping distance. As a result of the braking test of the vehicle equipped with ABS of the previous study, the average deceleration of the vehicle was 0.79g ~ 0.94g. In addition, the deceleration value was calculated from 0.92g to 0.94g in the recent automobile safety evaluation braking test conducted by the Korea Automobile Testing & Research Institute. In addition, the deceleration value of 0.55g ~ 0.71g was calculated through the analysis of EDR data performed in this study, and the value was smaller than the deceleration value measured in the braking experiment of the previous study.

• Korean Journal of Remote Sensing
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• v.11 no.3
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• pp.101-116
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• 1995

The fact that the demands on traffic data collection are imposed by economic and safety considerations raisese the question of the potential for complementing existing traffic data collection programs with satellite data. Evaluating and monitoring traffic characteristics is becoming increasingly important as worsening congestion, declining economic situations, and increasing environmental sensitivies are forcing the government and municipalities to make better use of existing roadway capacities. The present system of using automatic counters at selected points on highways works well from a temporal point of view (i.e., during a specific period of time at one location). However, the present system does not cover the spatial aspects of the entire road system (i.e., for every location during specific periods of time); the counters are employed only at points and only on selected highways. This lack of spatial coverage is due, in part, to the cost of the automatic counters systems (fixed procurement and maintenance costs) and of the personal required to deploy them. The current procedure is believed to work fairly well in the aggregate mode, at the macro level. However, at micro level, the numbers are more suspect. In addition, the statistics only work when assuming a certain homogenity among characteristics of highways in the same class, an assumption that is impossible to test whn little or no data is gathered on many of the highways for a given class. In this paper, a remote sensing system as complement of the existing system is considered and implemented. Since satellite imagery with high resolution is not available, digitized panchromatic imagery acquired from an aircraft platform is utilized for initial test of the feasibility and performance capability of remote sensing data. Different levels of imagery resolutions are evaluated in an attempt to determine what vehicle types could be classified and counted against a background of pavement types, which might be expected in panchromatic satellite imagery. The results of a systematic study with three different levels of resolutions (1m, 2m and 4m) show that the panchromat ic reflectances of vehicles and pavements would be distributed so similarly that it would be difficult to classify systematically and analytically remotely sensing vehicles on pavement within panchromatic range. Anaysis of the aerial photographs show that the shadows of the vehicles could be a cue for vehicle detection.

• International Journal of Highway Engineering
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• v.13 no.3
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• pp.39-49
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• 2011

The porous pavement system is widely considered very effective in urban street because of its various benefits on safety and environment, but the pavement thickness design system has not been established yet. In porous pavement system. rainwater penetrates to the subgrade through porous pavements layers. Porous pavements are expected to reduce or alleviate the problems caused by impermeable pavement layer such as flood damage due to heavy rain in the city, drainage load, disorder in ecosystem, and heat island. However, its structural design methods in traffic roads has not been made mainly because of not being able to consider adequately the effect of rainwater on subgrade strength. In this study, structural design method of porous pavements is suggested after considering the subgrade weakness due to rainwater and numerical mechanical analysis. It is noted that elastic modulus of subgrade is reduced by 20% as subgrade moisture content is increased by 2% at optimum moisture content in the literature review. As a result of both finite element analysis and strength loss of subgrade by the existing design method, it is necessary to increase subbase thickness about 30cm in porous pavements compared with the existing traffic road pavement system. It is similar to premium thickness of structural design of porous pavements in Japan.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.481-489
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• 2017

The study area,Cheonan Stream, is an urban river that flows through urban areas in close proximity to densely populated areas and multi-use facilities. The natural river improvement project from 2006 to 2015 improved the quality of life of local residents with the improvement of river function, the restoration of the natural ecosystem and the securement of hydrophilic space. A bike way in the constructed waterside space was built focusing on trails. This study suggests improvements appropriate for insufficient bike way function-related regulations. The problems of ramps, river crossing facilities, stairway facilities, safety facilities, signs, road markings, and parking facilities, etc.have arisen in the utilization situation and citizen consciousness survey. As an improvement, it was suggested that 12% or fewer ramps should be improved, a submerged bridge should be installed at 7 places separated by stepping bridges, and signs and road markings according to bike way-related regulations should be installed and bike parking facilities at Cheonan station and Cheonan bus terminal should be expanded. The bike way in the waterfront of ChoenanCheon(river) will increase the accessibility and utilization rate of short-distance transportation with the institutional expansion of bike use facilities and work organizations and the improvement of facilities in accordance with urban rivers and bike-related regulations. Therefore, it is expected that the development of the living space will be beneficial for the citizens due to the elimination of traffic in the city and the activation of bike traffic.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.401-404
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• 2008

Bridges are exposed to very severe environment and experience, as service life increased, elevated traffic load and traffic flow, in addition to natural disasters. In comparing to other road structures, bridges may cause more significant damage, such as human-involved accidents, to the society in the event of collapse. A certain level of service shall be necessarily secured to assure the minimum safety of users. The cost for manage and preserve bridges will increase gradually and more restrictions will be loaded to efficiently distribute the limited resources, such as monetary budget and human resource etc. In order to enhance performance and serviceability of bridges with the limited resource, asset management technique has been applied into the bridge management system, which capitalizes the road infrastructures including bridges and assess them in accordance with the government finance report. In the application of asset management, there must be a tool for assess the performance of bridges and this study introduces the basic information on the definition and role of performance measures for asset management for bridges.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.3
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• pp.243-248
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• 2015

Domestic road and railroad construction have been increasingly growing and for reasons of mitigating traffic congestion, urban plan and refurbishment project, deeper and longer tunnels have been built. The event of fire is the most fatal accident in a tunnel, and it can be very disastrous with a high possibility. In this study, QRA (Quantitative Risk Analysis) which is one of quantitative risk analysis approaches was applied to tunnel fire safety design and the evaluation of QRA cases and the cost comparison of QRA methods were carried out. In addition analysis of risk reduction effect of tunnel fire safety system was conducted using AHP (Analytic Hierarchy Process) and the priority of major factors that could mitigate the risk in tunnel fire was presented. As a result, significant cost reduction effect could be obtained by incorporating QRA and it is expected to design fire safety system rationally. The priority of fire safety system based on risk mitigation effect by fire safety system considering the cost is in order of water pipe, emergency lighting, evacuation passage and smoke control system.

• Journal of Korean Society of Transportation
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• v.23 no.5 s.83
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• pp.73-81
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• 2005

Triangle-shaped island was been used for the exclusive separation between the right-turn and the through flow. However, in case that existing Triangle-Shaped Island is built at the intersection of narrow road. there are more possibilities of traffic collision trespassing into the opposite lane. Accordingly, separation of the opposite lane is required so as to prevent the intrusion of the large-sized (a heavy) vehicle into the opposite lane turning at the intersection. This study showed the comparison between intersection composed of existing Triangle-Shaped Island and the intersection with Drop Island is added. First of all, in the safety aspect, a method to decide location and shape of Drop Island considering turning trajectory of the large-sized (the heavy vehicle) is addressed. The guideline on the placement of drop island install location and method to decide form the consider heavy truck's turn trajectory in safety side. As a conclusion. we analyzed that drop island is relatively superior to existing Triangle-Shaped Island in terms of driver, ease of driving, driving pleasantness, pedestrian, widening and economic performance aspect.