• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.3
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• pp.309-321
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• 2007

Since the first diesel passenger car hit the local road in late 2005, the share of diesel cars is growing significantly; possibly up to the level as in the western Europe. In this study, the effects of introduction of diesel passenger cars on the ventilation rate and facility capacity are analyzed for the three individual cases with different basic exhaust rate based on the vehicle age, the vehicle class percentage and the smoke exhaust rate. The target tunnel for this comparative study is a typical 2 km-long 2-lane highway tunnel. Case 1 assuming the current local design standards and the diesel vehicles comprising 40% of the total passenger cars on the road required more ventilation rate and facility capacity than in the case only with the current standards. Case 2 which is the real tunnel currently in the designing stage taking into account the vehicle age but ignoring the diesel vehicle ratio, and Case 3 on the contrary considering the both factors show similar level of ventilation characteristics as EURO-3 emission regulation. Application of the emission standard set by the Ministry of Environment for newly manufactured vehicles in the current local tunnel design standard indicates higher requirements than for EURO-2 regulation, whereas the emission standard came into effect in 2006 results in the ventilation characteristics similar to EURO-4. This study aims at providing fundamental information for assessing the basic emission rate and determining the optimal ventilation rate and facility capacity considering the growing percentage of diesel cars and gradually decreasing level of smoke emission forced by the relevant laws.

• Korean Journal of Optics and Photonics
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• v.28 no.6
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• pp.273-280
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• 2017

In this paper, a freeform reflector is designed for low road lighting. In the case of low road lighting, which requires light distribution over a wide lane compared to the height, it is difficult to match uniformity, compared to existing road lighting. To satisfy road lighting grade M3, the reflector was divided into nine parts, and the inclination of the reflecting surface was changed to have the desired light distribution. The fitted curves were drawn based on each point, following the formula that was derived. Through the Street Light Simulation of LightTools, we confirmed that it meets the M3 road lighting standard; we then made it directly and satisfied the lighting grade on an actual road, proving the validity of the design result.

• Journal of Korean Society of Transportation
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• v.35 no.5
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• pp.385-395
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• 2017

This study deals with the small-scale roundabout. The purpose of this study is to analyze the average delay of vehicle in roundabout, and suggest the efficient planning and design standard. In pursuing the above, this study gives particular attentions to analyzing the average delay time according to the inscribed circle diameter, speed of circulatory roadway lane and traffic volume. The operational efficiencies of 96 scenarios (3 sizes of inscribed circle diameter ${\times}$ 4 types of circulatory roadway speed ${\times}$ traffic volume) are analyzed using VISSIM (Verkehr In $St{\ddot{a}}dten$-SIMulationsmodell). The main results are as follows. First, the optimal design speed of small-scale roundabout are derived from the above scenario analysis. Second, the traffic volume of LOS D is estimated to be 2,180-2,740pcph. Third, the traffic volume of LOS F that is required to improve is above 2.780pcph. The results might be expected to give some implications to providing the countermeasures for the operational efficiency of roundabout.

• Tunnel and Underground Space
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• v.27 no.3
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• pp.132-145
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• 2017

Shock loss was not applied for the tunnel ventilation of road tunnel in the past. However, pressure losses due to the shock loss can be significant in network double-deck road tunnel in which combining and separating road structures exist. For the optimum ventilation design of network double-deck road tunnel, this study conducted 3D CFD numerical analysis for the shock loss at the combining and separating flows. The CFD model was made with the real-scale model that was the standard section of double-deck road tunnel. The shock loss coefficient of various combining and separating angles and road width was obtained and compared to the existing design values. As a result of the comparison, the shock loss coefficient of the $30^{\circ}$ separating flow model was higher and that of the two-lane combining flow model was lower. Since the combining and separating angles and road width can be important for the design of shock loss estimation, it is considered that this study can provide the accurate design factors for the calculation of ventilation system capacity. In addition, this study conducted 3D CFD analysis in order to calculate the shock loss coefficient of both combining and separating flows at flared intersection, and the result was compared with the design values of ASHRAE. The model that was not widened at the intersection showed three times higher at the most, and the other model that was widened at the intersection resulted two times higher shock loss coefficients.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.8
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• pp.1593-1598
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• 2012

In this paper, we propose an intelligent signal control method based on fuzzy logic applicable in real time. We design membership functions to model occupied time and the number of vehicles for each lane. A priority for each signal phase is computed by the popular Max-Min fuzzy inference based on control rules and membership degrees of prepared two functions at any given time. A tie breaking scheme is considering weighted sum of the rate of occupied time per number of vehicles in that block and the standard deviation of these blocks. Only a signal phase with the highest priority is opened and all others are closed and the duration of the phase opening is computed proportional to the rate of number of weighting vehicles in that signal per all weighted vehicles. The simulation result shows that the proposed method is more efficient than the static control in all simulation conditions in $2{\times}3$ experimental designs with the number of vehicles in intersection and congestion degrees that have all three levels.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.4
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• pp.325-334
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• 2008

The standard prestressed concrete I-girder bridge (PSC I-girder bridge) is one of the most prevalent types for small and medium bridges in Korea. When determining the member forces in a section to assess the safety of girder in this type of bridge, the general practice is to use the simplified practical equations or the live load distribution factors proposed in design standards rather than the precise analysis through the finite element method or so. Meanwhile, the live load distribution factors currently used in Korean design practice are just a reflection of overseas research results or design standards without alterations. Therefore, it is necessary to develop an equation of the live load distribution factors fit for the design conditions of Korea, considering the standardized section of standard PSC I-girder bridges and the design strength of concrete. In this study, to develop an equation of the live load distribution factors, a parametric analysis and sensitivity analysis were carried out on the parameters such as width of bridge, span length, girder spacing, width of traffic lane, etc. As a result, the major variables to determine the size of distribution factors were girder spacing, overhang length and span length in case of external girders. For internal adjacent girders, the determinant factors were girder spacing, overhang length, span length and width of bridge. For internal girders, the factors were girder spacing, width of bridge and span length. Then, an equation of live load distribution factors was developed through the multiple linear regression analysis on the results of parametric analysis. When the actual practice engineers design a bridge with the equation of live load distribution factors developed here, they will determine the design of member forces ensuring the appropriate safety rate more easily. Moreover, in the preliminary design, this model is expected to save much time for the repetitive design to improve the structural efficiency of PSC I-girder bridges.

• International Journal of Highway Engineering
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• v.11 no.4
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• pp.69-78
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• 2009

Korea has achieved significant economic growth with building the Gyeongbu Expressway. As the number of new road construction projects has decreased, it becomes more important to maintain optimal status of the current road networks. One of the best ways to accomplish it is weight enforcement as active control measure of traffic load. This study is to develop High-speed Weigh-in-motion System in order to enhance efficiency of weight enforcement, and to analyze patterns of overloaded trucks on highways through the system. Furthermore, it is to review possibilities of developing overweight control system with application of the HS-WIM system. The HS-WIM system developed by this study consists of two sets of an axle load sensor, a loop sensor and a wandering sensor on each lane. A wandering sensor detects whether a travelling vehicle is off the lane or not with the function of checking the location of tire imprint. The sensor of the WIM system has better function of classifying types of vehicles than other existing systems by detecting wheel distance and tire type such as single or dual tire. As a result, its measurement errors regarding 12 types of vehicle classification are very low, which is an advantage of the sensor. The verification tests of the system under all conditions showed that the mean measurement errors of axle weight and gross axle weight were within 15 percent and 7 percent respectively. According to the WIM rate standard of the COST-323, the WIM system of this study is ranked at B(10). It means the system is appropriate for the purpose of design, maintenance and valuation of road infrastructure. The WIM system in testing a 5-axle cargo truck, the most frequently overloaded vehicle among 12 types of vehicles, is ranked at A(5) which means the system is available to control overloaded vehicles. In this case, the measurement errors of axle load and gross axle load were within 8 percent and 5 percent respectively. Weight analysis of all types of vehicles on highways showed that the most frequently overloaded vehicles were type 5, 6, 7 and 12 among 12 vehicle types. As a result, it is necessary to use more effective overweight enforcement system for vehicles which are seriously overloaded due to their lift axles. Traffic volume data depending upon vehicle types is basic information for road design and construction, maintenance, analysis of traffic flow, road policies as well as research.

• Journal of Korean Society of Transportation
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• v.29 no.3
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• pp.103-114
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• 2011

In this study, we discuss a fatal accident severity model obtained from the analysis of 112 crash sites collected since 2000, and the resulting relationship between fatal accidents and roadway geometry design. From the 720 times computer simulations for improving driving safety, we then reached the following conclusions:. First, the result of cross and frequency-analyses on the car accident sites showed that 43.7% of the accidents occurred on the curved roads, 60.7% on the vertical curve section, 57.2% on the roadways with radius of curvature of 0 to 24m, 83.9% on the roads with superelevation of 0.1 to 2.0% and 49.1% on the one-way 2-lane roads; vehicle types involved are passenger vehicles (33.0%), trucks (20.5%) and buses (14.3%) in order of frequency. The results also show that the superelevation is the most influencing factor for the fatal accidents. Second, employing the Ordered Probit Model (OPM), we developed a severity model for fatal accidents being a function of on various road conditions so as to the damages can be predicted. The proposed model possibly assists the practitioners to predict dangerous roadway segments, and to take appropriate measures in advance. Third, computer simulation runs show that providing adequate superelevation on the segment where a fatal accident occurred could reduce similar fatal accidents by at least 85%. This result indicates that the regulations specified in the Rule for Road Structure and Facility Standard (description and guidelines) should be enhanced to include more specific requirement for providing the superelevation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.93-99
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• 2017

The rate of traffic accidents that occurred in Korea last year is 10 out of every 100,000 people, ranking it 6th among the 35 OECD member countries. The accident rate of children with disabilities and elderly people is also high. The purpose of this study is to introduce traffic safety facilities which have been developed for the reduction of traffic accidents in non-urban areas in Korea through an analysis of the related literature, the accident factors using traffic accident analysis system data and traffic accident characteristics. Traffic safety integrated facilities for ICT-based pedestrian crossings are subject to cross-sectional coverage of child protection zones. The smart safety fence prevents vehicles from parking illegally and informs pedestrians that there is an access vehicle on the pedestrian crossing. The smart bump is designed to warn drivers who are not aware of the pedestrians. In order to standardize the appropriate form and size of the traffic safety facilities for pedestrian crossings, we constructed a standard model for each type, considering the road function, press classification, power, lane number, geometric form, etc. As a result, the rate of traffic accidents involving vulnerable people was reduced. In addition, it is anticipated that the maintenance costs will be reduced by the use of a solar power supply and their compatibility with the existing installed safety fences.

• Journal of Korean Society of Transportation
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• v.35 no.3
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• pp.234-246
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• 2017

The Seoul metropolitan government introduced the bus information systems, bus rapid transit to increase travel speed and punctuality but still suffer from insufficiency. This paper delivers a study verifying the external factors at near the bus stops. The dependent variable was set to the standard deviation of (1) travel time and (2) travel time to and from the bus stop in this study. The independent variables were set to (1) the number of routes, (2) traffic volume by bus type, (3) the number of bus bays, (4) the possibility of passing, (5) the distance to crosswalks and intersections, and (5) the presence of residential road. The results showed that the most significant factors included the link section speed, number of bus bay, distance to crosswalk, and the possibility of passing.