• Journal of Korean Society of Transportation
• /
• v.27 no.4
• /
• pp.55-61
• /
• 2009

In order to observe the impact of a type of vehicles for traffic flows and pavement, vehicle classifications is conducted. Korean Ministry of Land, Transport and Maritime Affairs provides 12-type vehicle classifications on National expressways, National highways, and Provincial roads. Current AVC (Automatic Vehicle Classification) devices decide vehicle types comparing measurements of vehicle lengths, wheelbases, overhangs etc. to a reference table including those of all types of models. This study developed an algorithm for macroscopic vehicle classification which is less sensitive to tuning sensors and updating the reference table. For those characteristics, trend lines in vehicle lengths and wheelbases are employed. To assess the algorithm developed, vehicle lengths and wheelbases were collected from an AVC device. In this experiment, this algorithm showed the accuracy of 88.2 % compared to true values obtained from video replaying. Our efforts in this study are expected to contribute to developing devices for macroscopic vehicle classification.

• International Journal of Highway Engineering
• /
• v.15 no.4
• /
• pp.107-116
• /
• 2013

PURPOSES: The liquid-type chemical warm-mix asphalt (WMA) additive has been developed. This study evaluates the basic properties of the additive and the mechanical properties of WMA asphalt and mixture manufactured by using the newly developed chemical additive. METHODS: First, the newly developed WMA additive was applied to the original asphalt by various composition of additive components and dosage ratio of additive. These WMA asphalt binders were evaluated in terms of penetration, softening point, rotational viscosity, and PG grade. Based on the binder test results, one best candidate was chosen to apply to the mixture and then the mechanical properties of WMA mixture were evaluated for moisture susceptibility, dynamic modulus, and rutting and fatigue resistance. RESULTS : According to the binder test, WMA asphalt binders showed the similar properties to the original asphalt binder except the penetraion index of WMA additive was a little higher than original binder. From the Superpave mix design, the optimum asphalt content and volumetric properties of WMA mixture were almost the same with those of hot mix asphalt (HMA) mixture even though the production and compaction temperatures were $30^{\circ}C$ lower for the WMA mixture. From the first set of performance evaluation, it was found that the WMA mixture would have some problem in moisture susceptibility. The additive was modified to improve the resistance to moisture and the second set of performance evaluation showed that the WMA mixture with modified chemical additive would have the similar performance to HMA mixture. CONCLUSIONS : Based on the various laboratory tests, it was concluded that the newly developed chemical WMA additve could be successfully used to produce the WMA mixture with the comparable performance to the HMA mixture. These laboratory evaluations should be confirmed by applying this additive to the field and monitoring the long-term performance of the pavement, which are scheduled in the near future.

• Journal of Wetlands Research
• /
• v.15 no.4
• /
• pp.543-553
• /
• 2013

In Korea, there have been many studies and progresses on various types of pilot scale or commercialized field scale Best Management Practices(BMP) during the last 10 years. Runoff characteristics of diffuse pollutants from different land uses are well identified and documented. However, for the coastal area connected directly with shoreline, runoff patterns and management schemes of non-point pollution were not fully studied. Recently, coastal area is emerging as a new development axis especially in west coast side of Korea such as Incheon city and Chungnam province, thus urbanized area rapidly increased but there are no buffer zones and BMP facilities to aim at preventing direct discharge of the first flush into coastal sea and beaches. In this study, parking area in Deacheon harbor, Boryeong City in Chungnam Province was selected and rainfall runoff was monitored for two year period in order to examine run-off features from which proper type of BMP suitable for coastal area is proposed. Coastal area usually has a low ground water level and consists of plain land, so that large scale BMP such as storm water retention pond and wetland requiring great excavation works is not best management plan. In addition, monitoring study shows that storm water from the paved parking area has a high salinity compared with those in storm water from the inland. High salinity is detrimental for the vegetation. Therefore, BMP employing least vegetative cover and also in terms of maintenance is a good option such as infiltration trench and porous pavement.

• International Journal of Highway Engineering
• /
• v.19 no.5
• /
• pp.107-115
• /
• 2017

PURPOSES : The piezoelectric energy road analysis technology using a three-dimensional finite element method was developed to investigate pavement behaviors when piezoelectric energy harvesters and a new polyurethane surface layer were installed in field conditions. The main purpose of this study is to predict the long-term performance of the piezoelectric energy road through the proposed analytical steps. METHODS : To predict the stresses and strains of the piezoelectric energy road, the developed energy harvesters were embedded into the polyurethane surface layer (50 mm from the top surface). The typical type of triaxial dump truck loading was applied to the top of each energy harvester. In this paper, a general purpose finite element analysis program called ABAQUS was used and it was assumed that a harvester is installed in the cross section of a typical asphalt pavement structure. RESULTS : The maximum tensile stress of the polyurethane surface layer in the initial fatigue model occurred up to 0.035 MPa in the transverse direction when the truck tire load was loaded on the top of each harvester. The maximum tensile stresses were 0.025 MPa in the intermediate fatigue model and 0.013 MPa in the final fatigue model, which were 72% and 37% lower than that of the initial stage model, respectively. CONCLUSIONS : The main critical damage locations can be estimated between the base layer and the surface layer. If the crack propagates, bottom-up cracking from the base layer is the main cracking pattern where the tensile stress is higher than in other locations. It is also considered that the possibility of cracking in the top-down direction at the edge of energy harvester is more likely to occur because the material strength of the energy harvester is much higher and plays a role in the supporting points. In terms of long-term performance, all tensile stresses in the energy harvester and polyurethane layer are less than 1% of the maximum tensile strength and the possibility of fatigue damage was very low. Since the harvester is embedded in the surface layer of the polyurethane, which has higher tensile strength and toughness, it can assure a good, long-term performance.

• International Journal of Highway Engineering
• /
• v.19 no.3
• /
• pp.19-30
• /
• 2017

PURPOSES : This study proposes the road asset valuation approach using alternative depreciation methods. It has become necessary to have asset management system according to the adoption of accrual basis accounting for governmental financial reporting and the amendment of the road act. Therefore, it is very important to analyze the effect of depreciation methods on road asset value as a basic research for road asset management system. METHODS : The Ministry of Strategy and Finance (MOSF) has mainly performed road asset valuation based on Write down Replacement Cost and Straight Line depreciation method. This study suggests some appropriate asset valuation methods for road assets through case analysis using three depreciation methods: Consumption-based depreciation method, Condition-based depreciation method, and Straight Line depreciation method. A road asset valuation data of national highway route 1 (year 2014) is used to analyze the effect of three depreciation methods on the road asset value. Road assets include land and structures (pavement, bridge, and tunnel). This study mainly focuses on structures such as bridges and tunnels, because according to governmental accounting standards, land and road pavement assets do not depreciate. RESULTS : The main results of this study are as follows. Firstly, overall asset value of national highway route 1 was estimated at 6.97 trillion KRW when MOSF's method (straight-line depreciation method) is applied. Secondly, asset value was estimated at 4.85 trillion KRW on application of consumption-based depreciation method. Thirdly, asset value was estimated at 4.37 trillion KRW when condition-based depreciation method is applied. Therefore, either consumption-based or condition-based depreciation methods would be more appropriate than straight-line depreciation method if we can use the condition data of road assets including land that are available in real time. CONCLUSIONS : Since road assets such as pavements, bridges, and tunnels have various patterns of deterioration and condition monitoring period, it is necessary to consider a specific valuation method according to the condition of each road asset. Firstly, even though road pavements do not depreciate, asset valuation through condition-based depreciation method would be more appropriate when requirements for application of non-depreciation approach are not satisfied. Since bridge and tunnel facilities show various patterns of deterioration and condition monitoring period by type and condition level, consumption-based depreciation method based on deterioration model would be appropriate. Therefore, it is necessary to have a reasonable asset management system to apply condition-based depreciation method and a periodic condition investigation to manage road assets well.

• Journal of the Society of Disaster Information
• /
• v.19 no.2
• /
• pp.305-312
• /
• 2023

Purpose: Although the damage caused by abnormal temperatures is extensive, blow-up or black ice is typical in concrete structures. In this study, PCM with high phase change energy was mixed with concrete to reduce temperature damage to concrete pavement. Method: In order to reduce temperature damage to low temperatures and high temperatures, capsule-type PCM with phase change temperatures of 4.5℃ and 44℃ was replaced by 10%, 30%, and 50%, and thermal performance experiments and compressive strength experiments were conducted using thermocouples and variable chambers. Result: As a result of the thermal performance experiment, it was found that the incorporation of PCM improves temperature resistance by up to 25% or more, and increases thermal resistance at all temperatures with high specific heat when substituted in large amounts. As a result of the compression strength experiment, a substitution of 30% or more resulted in a decrease in the compression strength, and a large strength difference was shown based on the phase change temperature of the PCM. Conclusion: The incorporation of PCMs has been shown to increase the thermal performance of concrete, with the greatest increase in thermal performance near the phase change temperature of PCM. In addition, a small strength reduction of 10% to 20% occurs at the highest substitution rate of 50% substitution, so there is no significant problem with usability, and additional PCM substitution is expected to improve thermal performance.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.2
• /
• pp.511-520
• /
• 2020

Owing to global warming, heat waves have become stronger in the summer, and research on improving the thermal environment of green spaces, such as urban parks, is being conducted. On the other hand, studies on improving the urban thermal environment, which is changing due to the greening pattern and the intensity of the wind, are still insufficient. This study analyzed the temperature of the green spaces on campus to understand the factors affecting the temperature changes. After investigating the covering condition and planting form of the site, factors, such as temperature, humidity, wind direction, wind speed, and illuminance, were measured. The most influential factors on the temperature distribution are evapotranspiration and wind - induced heat transfer. The other major factors affecting the temperature change were the type of cover, wind velocity/wind direction, type of planting, shade / solar irradiance. In the type of cover, the plant was classified as low temperature, and the asphalt pavement was classified as high temperature. In wind speed, instantaneous temperature was reduced by 1.2 ℃ in southern wind, 0.7 ℃ in the westerly wind, 0.4 ℃ in the north wind and 0.5 ℃ in the east wind when a wind of 3.5m/s or more was blown.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2004.04a
• /
• pp.472-472
• /
• 2004

Numerous studies on urban groundwater have been carried out in many other countries. Urban groundwater shows a unique hydrologic system because of complex urban characteristics such as road pavement, sewers and public water supply systems. These urban facilities may change the characteristics of groundwater recharge but contaminate its quality as well. There have been several researches on urban groundwater in Seoul. Seoul has been industrialized very rapidly so that the city has large population. The recent population in Seoul amounts to more than ten millions, corresponding to a very high density of about 17, 000 people/km$^2$. Therefore, many factors affect the groundwater quality and quantity in Seoul. Nowadays, groundwater in Seoul is being extracted for construction, industrial use, and drinking and so on. There are 15, 714 wells in Seoul and its annual usage is 41, 425, 977m$^3$(in 2001). Therefore, systematic studies are needed to properly manage and use the groundwater in Seoul. The purposes of this study in progress are to identify geochemical characteristics of groundwater in Seoul and to determine the extent of groundwater contamination and its relationship with urban characteristics. For this study, groundwater was sampled from more than 400 preexisting wells that were randomly selected throughout the Seoul area. For all samples, major cations together with Si, Al, Fe, Pb, Hg For 200 samples among them, TCE, PCE, BTEX were also analyzed by GC. Our study shows that groundwater types of Seoul are distributed broadly from Ca-HCO$_3$ type to Ca-Cl＋NO$_3$ type. The latter type indicates anthropogenic contamination. Among cations, Ca is generally high in most samples. In some samples, Na and K are dominant. The dominant anions change widely from HCO$_3$ to Cl＋NO$_3$. The anion composition is considered to effectively indicate the contribution of distinct anthropogenic sources. In addition, major ions are positively proportional to total dissolved solid (TDS) except K and NO$_3$. Thus, we consider that TDS may be used as an effective indicator of the extent of pollution. However, the increase of TDS may result from increased water-rock interaction. To determine the extent of groundwater contamination, it is needed to figure out the baseline water quality in Seoul. Furthermore, detailed geochemical studies are required to find out pollution sources and their corresponding hydrochemical parameters.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.5
• /
• pp.54-63
• /
• 2018

In this study, the stability and economic feasibility of a MSE (Mechanically stability earth) wall with a pre-cast concrete pacing panel was investigated for a standard section of highway. Based on the design criteria, the MSE walls of the panel type were designed considering the load conditions of the highway, such as the dead load of the concrete pavement, traffic load, and impact load of the barrier. The length of the ribbed metal strip was arranged at 0.9H according to the height of the MSE walls. Because the length of the reinforcement was set to 0.9H according to the height of the MSE wall, the external stability governed by the shape of the reinforced soil was not affected by the height increase. The factor of safety (FOS) for the bearing capacity was decreased drastically due to the increase in self-weight according to the height of the MSE wall. As a result of examining the internal stability according to the cohesive gravity method, the FOS of pullout was increased and the FOS of fracture was decreased. As the height of the MSEW wall increases, the horizontal earth pressure acting as an active force and the vertical earth pressure acting as a resistance force are increased together, so that the FOS of the pullout is increased. Because the long-term allowable tensile force of the ribbed metal strip is constant, the FOS of the fracture is decreased by only an increase in the horizontal earth pressure according to the height. The panel type MSE wall was more economical than the block type at all heights. Compared to the concrete retaining wall, it has excellent economic efficiency at a height of 5.0 m or more.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.20 no.1
• /
• pp.100-118
• /
• 2021

In this study, PM accidents (1,603case) and bicycle accidents (14,672case) that occurred in the last three years were analyzed to determine the characteristics of PM traffic accidents. In particular, PM traffic accidents were divided into perpetrators and victims to determine the characteristics in detail. For PM accidents, the analysis was conducted on the status of each road grade, road type, weather condition, accident type, day and night occurrence, and vehicle type. The number of PM accidents that occurred in 2019 increased by 129%, and deaths increased by more than 200% compared to the previous year. The proportion of pedestrian accidents among PM traffic accidents was higher than that of bicycle accidents. Therefore, regulations on PM traffic are necessary. For the 20 deaths of PM, a detailed analysis was conducted to analyze the factors of traffic accidents. PM fatalities occurred in 50% of vehicle accidents, and 7 out of 10 vehicle accidents occurred at night. This is believed to have been caused by falling or overturning due to an obstacle, such as a depression in the road pavement or a speed bump.