• Journal of Korean Society of Transportation
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• v.23 no.4 s.82
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• pp.17-28
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• 2005

About 91.1% of Railway-Highway Crossings (RHC) in Korea use a Constant Distance Warning System(CDWS), while about 8.9% use a Constant Warning Time System(CWTS). The CDWS does not recognize speed differences of approaching trains and provides only waiting times to vehicles and pedestrians based on the highest speed of approaching trains. Under the CDWS, therefore, low speed trains provide unnecessary waiting times at crossings which often generates complains to vehicle drivers and pedestrians and may cause wrong decisions to pass the crossings. The objective of this research is to improve the safety of the RHC by developing accurate a CWTS. In this research a train speed and location detection system was developed with ultra sonic detectors. Locations of the detectors was decided based on the highest speed and the minimum warning time of Saemaul of 160 km/h. To validate the algorithms of the newly developed systems the lab tests were conducted. The results show that the train detection system provides accurate locations of trains and the maximum error between real speeds of trains and those of the system was 0.07m/s.

• International Journal of Highway Engineering
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• v.8 no.1 s.27
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• pp.89-98
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• 2006

The weight-to-power ratio of the standard truck for the climbing lane design is known to be 200lb/hp. The value was known to be assumed based on constant trucks' capability and regional distributions in stead of widely varied distributions region by region. Additionally, this value was assumed after investigating registered vehicles' statistics instead of investigating real portions of truck volumes. Therefore, it may be said that the value of the current standard truck does not reflect regional or industrial diversity and proportions of truck volumes. To resolve these issues, the present paper studies diversified standard trucks which consider regionally or industrially diversified and observed-volume based weigh-to-power ratios. For this purpose, individual trucks' weigh-to-power ratios obtained at toll-gates of national expressways were used. For regionally based study, the whole nation are divided into 8 regions, then each region is characterized by a unit of a weigh-to-power ratio. The applicability of each value is provided. Results show that the single value for the nationwide standard truck may be 208 lb/hp, 8 lb/hp higher than the current value of 200 lb/hp. Results also show that regional values ranged widely from 170 lb/hp to 230 lb, 30 lb/hp higher/lower than the current value. Conclusively, regional diversity of trucks' weigh-to-power ratios was identified then three types of standardized weigh-to-power ratios which may represent regional characteristics were suggested. As the diversified standard truck are applied to the design standard, two benefits are expected such as decrease of rear-end accident rates or decrease of climb lane construction costs.

• International Journal of Highway Engineering
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• v.4 no.2 s.12
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• pp.33-42
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• 2002

The cracks in the pavements result from drying shrinkage, temperature change, repeated traffic loadings and so on. The reduction of soil support, spatting and many local failures are caused by water and incompressible foreign materials infiltrated into the cracks. In order to reduce this kind of problems the crack width must be controlled and managed by the accurate measurement. The current method is a visual survey using a microscope, which requires traffic blocking. The purpose of this study is to find the best condition to measure accurate crack width using automated pavement condition survey equipment running at the similar speed as other vehicles. In this study pavement surfaces are filmed on an enlarged scale by the camera with a zoom lens, and then the proper focal distance is determined according to the crack width through a pilot survey. The conditions for measurement of the accurate crack width using the image processing technique are suggested by comparing crack widths surveyed using a microscope in the field with those computed by various factors in the image processing program, STADI-2. In conclusion, the camera with a focal distance of 75m could detect crack range of 0.5mm$\sim$1.2mm In width with an accuracy of 80% for CRCP. The camera with a focal distance of 12.5mm could detect crack range of 1.8mm$\sim$3.3mm in width with an accuracy of 90% for asphalt pavement.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.159-166
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• 2011

Green house gas emissions are increasing as development of the industrial economy of the international community. Many countries in the world are endeavoring to reduce green house gas emissions under severe climate change. In order to protect grobal warming, government is trying to reduce green gas emissions under "Low Carbon Green Growth Policy" and investing climiate-firendly industries such as renewable energy harvesting. Renewable energy has been rapidly developing as a result of investment for development technology of using natural energy such as solar, wind, tidal, etc. There are lots of waste energy in the road space. However, nobody is not interested in waste energy from the road space. This paper present a fundamentally experimental study of energy harvesting technique to use waste energy in the road. The waste energy in the road is covered a pressure and impact of vehicles on the road, the radiant heat from asphalt pavement, road noise and vibration etc. In this study, an energy harvesting device using piezoelectric element is proposed and various tests are conducted to investigate a characteristic of this device as function of impact loading based on piezoelectric effect behavior. This paper shows the energy harvesting results of the device using domestic piezoelectirc element as a function of impact load size and pavement types.

• International Journal of Highway Engineering
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• v.13 no.1
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• pp.139-148
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• 2011

Asphalt concrete overlay method is used by general maintenance and rehabilitation of construction for aged concrete pavement in Korea. However, in case of the AC overlay method to extend service life of the existing concrete pavements, various distresses of reflection crack, pothole and rutting are the typical problems of the asphalt overlay on existing concrete pavement since it has different physical characteristics between asphalt overlay and existing concrete pavement. To achieve this, application of concrete overlay method is required instead of AC overlay method. Concrete overlay method has advantages that can reduce maintenance cycle and costs since it has excellent bearing value for heavy vehicles and no rutting. However, technical problems of detour road construction, traffic control and other disadvantages happened by long curing time. Thus, in this study and experimental research were launched to evaluate the workability, durability and resistance against environmental loading of Very Rapid Hardening Acrylic Polymer Modified Concrete(VRH-APMC) for application of bonded concrete overlay method. Test results showed that the compressive and bond strength were exceed 21MPa and 1.4MPa of target strength after four hours for rapid traffic opening properties. And tests of resistance against environmental loading results showed that VRH-APMC secured excellent durability. Thus, it was known that VRH-APMC was suitable material for large scale bonded concrete overlay method, and it was possible to use maintenance and rehabilitation method which needs enough workability and rapid traffic opening.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.1D
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• pp.7-15
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• 2011

The travel time value is important factor for the evaluation of feasibility the transportation facility investment. The existing method for calculation of the travel time for each mode uses daily average trip purpose. So the value of travel time is constant because it is estimated with only daily average proportion. This daily constant time value can distort the results of future demands of toll roads or economic appraisals for the projects. The proportion of the trip purpose varies by time periods. Accordingly the value of travel time also varies by time periods. In this study, times periods are classified as morning peak, evening peak, business time off-peak, and non-business time off-peak. And trip purpose proportions are sorted by each time period from raw data of Seoul household trip study, then the value of travel time for each time period is estimated with these sorted purpose proportions. A case study of Seoul Jung-gu and Yongsan-gu performed with newly estimated time value by time periods. The result of benefit calculation with the daily constant time value is overestimated approximately annual 2.5 billion Won compared by time values by time periods. The demands of toll roads are also overestimated with the existing daily constant time value by daily 3,500 vehicles and total revenue of toll roads are overestimated by annually 1 billion Won. In conclusion, the value of travel time by each time period enables the more precise economic evaluation of the transportation facility investment projects, mode choice behavior, and route choice behavior especially for toll roads.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.198-206
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• 2016

Fuel economy label will be used as a national indicator in energy management, leading to the development of car technology manufacturer and plays a role in providing consumer vehicle purchase information. But the government's fuel economy label is continued consumer complaint is different and diminishing fuel economy were introduced by the government to measure the exact fuel economy label than resetting the 5-cycle test method in the US for the domestic vehicle standards. Originally two test mode in order to reduce the impact of the sharp increase in the resources required but methods of calculating a measured result value by driving all of the five test mode a variety of environmental conditions and the running pattern is reflected to the fuel economy label (city( FTP-75 mode), highway(HWFET mode)) and using 5-cycle correction formula for calculating a fuel consumption value and the equivalent value to calculate the result of the 5-cycle test. The compensation was calculated expression 30s, 5-Cycle Test Method of vehicles in 2011 was considered necessary to review the existing 5-cycle correction formula for the New Type car due to the recent rapid development of automotive technology. In this study, recent technology is targeting 14 units New Type car applied over the same test method and the existing check test mode specific fuel economy properties and, as a result of analyzing the corrected expression differences that have already been developed with the existing test vehicle resulting large did not show the difference was found to correction formula also not getting the existing fuel correction expression significant effect on the improvement of the current automobile technology as a maximum error of less than 1.5%.

• Journal of Korean Society of Transportation
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• v.33 no.5
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• pp.449-460
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• 2015

The reliability of air quality evaluation results for green transportation could be improved by applying correct emission factors. Unlike previous studies, which estimated emission factors that focused on vehicles in laboratory experiments, this study investigates emission factors according to road types and time using real driving data. The real driving data was collected using a Portable Activity Monitoring System (PAMS) according to road types and time, which it compared and analyzed fuel consumption from collected data. The result of the study shows that fuel consumption on national highway is 17.33% higher than the fuel consumption on expressway. In addition, the average fuel consumption of peak time is 4.7% higher than that of non-peak time for 22.5km/h. The difference in fuel consumption for road types and time is verified using ANOCOVA and MANOVA. As a result, the hypothesis of this study - that fuel consumption differs according to road types and time, even if the travel speed is the same - has proved valid. It also suggests correction factor of emission factors by using the difference in fuel consumption. It is highly expected that this study can improve the reliability of emissions from mobile pollution sources.

• Journal of Korean Society of Transportation
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• v.33 no.1
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• pp.40-49
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• 2015

In this study, the effects of inertial driving on a fuel-cut zone were analyzed by measuring the instantaneous variations of fuel consumption and speed. Thirteen sites with 2-8% downhill slopes were selected for the vehicle experiments. The vehicles were driven on the sites in two different driving modes, and the various vehicle states were measured using OBD under driving. For the analysis of the effects of inertial driving, the characteristics of fuel consumption, speed, and rpm were compared between normal and inertial driving. As a result, the fuel consumption was reduced from 24% to 78% according to the downhill grade. The amount of fuel consumption reduction was about 30cc for driving 500m downhill. Fuel cost savings amounting to 35 billion won can be achieved if inertial driving will be done in the case of Munemi-ro3. It is also believed that the reduced fuel consumption and vehicle speed through inertial driving will have considerable environmental and safety benefits.

• Journal of Korean Society of Transportation
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• v.28 no.4
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• pp.141-156
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• 2010

In this paper, understanding there is a limitation with a comprehensive and network approach for the evaluation of existing vehicle and pedestrian environments, the authors focus on developing an integrated approach to assessing these environments. The network evaluation here means the assessment at a three-dimensional level that includes evaluation methods of lines/axes in a spatial concept as well as integration of evaluation indicators being used for vehicles and the walking environment. Grey System Theory (GST) was applied based on the theoretical background for network and comprehensive integrated evaluation, and the evaluation of the vehicle and pedestrian environment was performed by assigning target areas to walking preference zones. As a result of the comprehensive evaluation and analysis by GST, even if the service level is the same as the operating indicators (Highway Capacity Manual) of the vehicle and pedestrian environment, or relatively better, it was identified that the total score could be varied over Grey Category because the observed data are calculated after considering the weights between evaluation indicators by the range of Grey Category on the comprehensive evaluation. Considering comprehensively these points, although the indicators on the operation of roads are relatively good, in the event that the indicators on the safety of roads are bad, it was known that the scores over Grey Category also could be changed. The result is that this evaluation method can be used to evaluate the network concept per lane (per axis) as well as to diagnose the current state by type of urban street in the future.