• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.565-568
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• 2006

This study was retentive material into the porosities of the permeable asphalt concrete, we developed retentive asphalt concrete which can absorb water in rain and decrease the temperature of the pavement through the vaporization of rainwater. The experimental results showed that the maximum stability appeared in the 5.0% types of both AP-5 and SBS PMA. Between these two types, the maximum stability of the asphalt with AP-5 was 480kg, which means it met the stability requirement for walkways but didn't meet the requirement for roadways. On the other hand, the maximum stability of the asphalt concrete with SBS PMA was 676kg, which was 176 kg higher than the requirement for roadways(500kg) and satisfy the requirement of KS. The retentive material was 56.4% in the type of the retentive material with 30% diatomaceous earth, 66.6% in 50% type, 87.5% in 70% type. In the aspect of thermal properties, the retentive asphalt concrete can lower the surface temperature by about 15 degrees lower than the normal asphalt concrete can. This effect could be made by the evaporation cooling effect and the surface albedo. It should be noted that the evaporation cooling effect cools it by about 10 degrees and the surface albedo by about 5 degrees.

• International Journal of Highway Engineering
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• v.19 no.3
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• pp.45-55
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• 2017

PURPOSES: The objective of this study is to estimate required minimum spacing between Freeway IC for high-speed roadways. METHODS : Since high-speed roadways with over 140 km/h design speed do not exist in Korea, VISSIM Simulation Program was used for analysis. Acceleration noise and conflicts were selected for Evaluation Index. Standard deviation size for acceleration and deceleration was calculated by VISSIM to estimate acceleration noise. Conflicts were produced in areas between Freeway IC with SSAM. RESULTS : As a result, required minimum spacing was 6 km for acceleration noise analysis, while 5 km was deducted for conflict analysis. For Model Evaluation, with SAS, conflicts did not show much difference in 5~6 km area by 90% confidence interval. CONCLUSIONS : For acceleration noise, results showed lacking in its discrimination between index per Minimum Spacing. However, conflicts were valid in difference; required minimum spacing was 5 km by validation result.

• Journal of Auto-vehicle Safety Association
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• v.15 no.2
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• pp.6-12
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• 2023

For the commercialization and standardization of autonomous vehicles, demand for rigorous safety criteria has been increased over the world. In Korea, the number of extraordinary service permission for automated vehicles has risen since Hyundai Motor Company got its initial license in March 2016. Nevertheless, licensing standards and evaluation factors are still insufficient for operating on public roadways. To assure driving safety, it is significant to verify whether or not the vehicle's decision is similar to human driving. This paper validates the safety of the autonomous vehicle by drawing scenario-based comparisons between manual driving and autonomous driving. In consideration of real traffic situations and safety priority, seven scenarios were chosen and classified into basic and advanced scenarios. All scenarios and safety factors are constructed based on existing ADAS requirements and investigated via a computer simulation and actual experiment. The input data was collected by an experimental vehicle test on the SNU FMTC test track located at Siheung. Then the offline simulation was conducted to verify the output was appropriate and comparable to the manual driving data.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.69-76
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• 2020

Global warming is a very important problem as it causes rapid climate change and natural disasters. Therefore, researches related to renewable energy are being actively conducted while promoting policies such as reducing carbon dioxide emission and increasing the proportion of renewable energy. Solar power generation is being applied in urban areas like BIPV as well as existing idle areas outside the city. Therefore, in this study, precast concrete blocks developed for paving roadways capable of solar power generation were designed and constructed. For the evaluation of field applicability for 6 months, skid resistance and block settlement were measured. As a result of the experiment, it was found that skid resistance satisfies the standard of general roadway in Korea, but not the standard of highway. The skid resistance tended to decrease as time passed. In addition, the settlement of the block gradually increased slightly, but it is much smaller than the allowable settlement of the roadway. Therefore, it is necessary to establish a maintenance period and method based on the periodic measurement results in the future.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.861-868
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• 1999

Drainage concrete pavement, unlike water permeable concrete pavement, is to preclude the pavement from overflowing with water, such as rain water, from infiltrating into earth by placing a border in the middle layer which makes water to flow through the surface of the border to the conduit. Drainage concrete pavement enhances car wheel resistance to slippery and wet road surface and imbibes noise caused by friction on the road. Also, by using pigment, it adds to the beauty of the environment. Drainage concrete pavement can be used for sidewalks, roadways, parking lots and expressways.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.329-334
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• 1997

Most of domestic pavement were non-permeable. However, in foreign country although it wasn't entirely satisfied, porous pavement was partially utilized with footpaths and soft-roadways. In this study, experiments were carried out to investigate the properties fundamental of porous concrete pavement. As a result of experiments, it was concluded that the coefficient of permeability was increased in proportion to continuous void ratio and decreased in proportion to S/a ratio and unit cement contents. On the other hand, the strength of porous concrete pavement was in inverse proportion to the void ratio.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.5 no.1 s.9
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• pp.55-63
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• 2006

Speeding is one of the major causes of traffic accidnets in urban areas. Driver feedback sign(DFS) is a traffic control device that can be used for many traffic environments including work zones, school zones, and roadways. In this paper, the effectiveness of DFS was evaluated through a field study using speed data collected from before and after study periods. In addition traffic safety improvement was also quantitatively estimated using the variance of speed data collected. Staistical test results showed that the speed difference was statistically significant, and the distribution of speed data was also shifted greatly. Therefore, it was concluded that installing the DFS in roadways might lead to unifomity of speed of traffic flow, thus, potential safety improvement might be expected.

• International Journal of Highway Engineering
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• v.18 no.6
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• pp.35-40
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• 2016

OBJECTIVES : The objective of this study is to analyze the nonlinear behavior of block pavements using multi-load level falling weight deflectometer (FWD) deflections. METHODS : Recently, block pavements are employed not only in sidewalks, but also in roadways. For the application of block pavements in roadways, the structural capacities of subbase and subgrade are important factors that support the carry traffic load. Multi-load level FWD testing was conducted on block pavements to analyze their nonlinear behavior. The deflection ratio due to the increase in load was analyzed to estimate the nonlinearity of block pavements. Finite element method with nonlinear soil model was applied to simulate the actual nonlinear behavior of the block pavement under different levels of load. RESULTS : The results of the FWD testing show that the center deflections in block pavements are approximately ten times greater than that in asphalt pavements. The deflection ratios of the block pavement due to the increase in the load range from 1.2 to 1.5, indicating that the deflection increased by 20~50%. The material coefficients of the nonlinear soil model were determined by comparing the measured deflections with the predicted deflections using the finite element method. CONCLUSIONS : In this study, the nonlinear behavior of block pavements was reviewed using multi-load level FWD testing. The deflection ratio proposed in this study can estimate the nonlinearity of block pavements. The use of nonlinear soil model in subbase and subgrade increases the accuracy of predicting deflections in finite element method.

• International Journal of Highway Engineering
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• v.10 no.2
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• pp.91-100
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• 2008

The quality of service on urban roadways have been evaluated mainly based on such quantitative measures as travel speed and delay. However, in addition to the quantitative aspects, drivers traveling on urban roadways are subject to be influenced by qualitative measures such as aesthetic aspects of the roadway and other drivers' violation of traffic laws. Based on this notion, this study attempts to identify roadway service quality indices, considering both qualitative and quantitative aspects and evaluate the quality of service using the modified Importance-Performance Analysis (IPA), a technique often applied in the field of marketing. The modified IPA is proposed in this study as a way to evaluate the service quality, reflecting the relative performance between study areas and performance indices. A case study is implemented over the Gangnam and Gangbuk areas in Seoul, resulting in identifying the items needed to be improved for each study area.

• Geomechanics and Engineering
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• v.11 no.3
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• pp.401-420
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• 2016

The stability of deep coal roadways with large sections and thick top coal is a typical challenge in many coal mines in China. The innovative Universal Discrete Element Code (UDEC) trigon block is adopted to create a numerical model based on a case study at the Dongtan coal mine in China to better understand the failure mechanism and stability control mechanism of this kind of roadway. The failure process of an unsupported roadway is simulated, and the results suggest that the deformation of the roof is more serious than that of the sides and floor, especially in the center of the roof. The radial stress that is released is more intense than the tangential stress, while a large zone of relaxation appears around the roadway. The failure process begins from partial failure at roadway corners, and then propagates deeper into the roof and sides, finally resulting in large deformation in the roadway. A combined support system is proposed to support roadways based on an analysis of the simulation results. The numerical simulation and field monitoring suggest that the availability of this support method is feasible both in theory and practice, which can provide helpful references for research on the failure mechanisms and scientific support designing of engineering in deep coal mines.