• Journal of Korean Society of Forest Science
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• v.97 no.4
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• pp.467-477
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• 2008

This study is analyzed on user's activities and recreational value through a questionnaire on users of the forest road in urban forest. Users visiting the forest road in urban forest went to there about three times a week, and the re-visit intention was showed highly. The forest road in urban forest is used too much for the promotion of health as a walk and a mountain pass of the citizen, and they think that forest road is useful for forest recreation. The satisfaction grade on forest road's equipment was effective above the average. As the result of valuation on recreational value of forest road in urban forest, the recreational value was evaluated 153.2 won. So, if it is collected the using fees for forest road, it was showed that it is proper about 150 won for one person.

• Journal of Environmental Science International
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• v.16 no.5
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• pp.611-622
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• 2007

The purpose of this research was to three-criteria landuse-pattern, developing density, NDVI which were related to the heat island and find the distribution characteristic of urban surface temperature and urban heat island effects. The results of this study were as follows. According to the analysis of surface temperatures, the first grade was the outside-city like a mountain and its temperature was less than $12.18^{\circ}C$. The fifth grade was the downtown industrial area and its temperature was more than $23.54^{\circ}C$. It means Daegu-Metropolitan-City has the serious heat-island effect. the results of landuse pattern analysis, in case of fifth and forth grade, city area was occupied over 90% with residential, commercial and industrial areas, but in case of third grade, openspace was occupied over 70%. The results of developing density analysis, the temperature had high correlation with building ratio, road ratio, vegetation ratio and etc. To plan for the decrease of heat island effect needed the extension of green space, decrease of paving, but there was a limit to get the objective method for grade classification because of lacking in the basic data, the research of criteria will be accomplished continuously.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.718-727
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• 2000

Nowadays, most passenger cars equipped with automatic transmissions use torque converter clutches to reduce fuel consumption, and recently the slip control scheme of torque converter clutches is widely studied for the expansion of the operating region of torque converter clutches and thus for the further improvement of the fuel economy of vehicles. In this study, the analysis of the torque converter clutch system including the line pressure control unit of the automatic transmission and the actuating hydraulic control unit of the torque converter clutch is performed, and a feedforward controller and a fuzzy logic controller for its slip control are proposed. Also, for the slip controller to use the grade resistance information during control, an observer-based grade resistance estimator is designed. The performance of the designed grade resistance estimator and the slip controller is verified by dynamic simulations, and the effect of the torque converter clutch slip control on the fuel economy is examined using a driving cycle simulation.

• International Journal of Highway Engineering
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• v.14 no.5
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• pp.47-55
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• 2012

PURPOSES: SUPERPAVE binder grade tests including Multiple Stress Creep and Recovery(MSCR) test are applied to evaluate rheological properties of four polymer modified binders. METHODS: To evaluate grade of four modified binders, PG testing protocols, such as DSR, BBR and MSCR are employed. RESULTS: It is observed that MSCR test shows different performance grades especially on modified binders. Both DMP and EG binder show similar high temperature performance to SBS 5% modified binder. CONCLUSIONS: Binder Grading system in Korea need to be reviewed to properly reflect the performnace of modified binders. The binders modified with DMP and EG can be possible alternatives SBS 5% modified binder considering its performance and cost.

• International Journal of Highway Engineering
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• v.18 no.6
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• pp.131-136
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• 2016

OBJECTIVES : The objective of this research is to determine the integrity of pavement structures for areas where voids exist. Furthermore, we conducted the study of voided-area analysis and remaining life prediction for pavement structures using finite element method. METHODS : To determine the remaining life of the existing voided areas under asphalt concrete pavements, field and falling weight deflectometer (FWD) tests were conducted. Comparison methods were used to have better accuracy in the finite element method (FEM) analysis compared to the measured surface displacements due to the loaded trucks. In addition, the modeled FEM used in this study was compared with well-known software programs. RESULTS : The results show that a good agreement on the analyzed and measured displacements can be obtained through comparisons of the surface displacement due to loaded trucks. Furthermore, the modeled FEM program was compared with the available pavement-structure software programs, resulting in the same values of tensile strains in terms of the thickness of asphalt concrete layers. CONCLUSIONS : The study, which is related to voided-area analysis and remaining life prediction using FEM for pavement structures, was successfully conducted based on the comparison between our methods and the sinkhole grade used in Japan.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.5
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• pp.576-582
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• 2015

Generally, the fuel economy of hybrid electric vehicle (HEV) is effected by the size of each component. In this study the fuel economy for HEV of our own making is evaluated using backward simulator, where dynamic programming is applied. In a competition, the vehicle is running through the road course that includes many speed bumps and steep grade. Therefore, the new driving cycle including road grade is developed for the simulation. The backward simulator is also developed through modeling each component. A performance map of engine and motor for component sizing is made from the existing engine map and motor map adapted to the HEV of our own making. For optimal component sizing, the feasible region is defined by restricting the power range of power sources. Optimal component size for best fuel economy is obtained within the feasible region through the backward simulation.

• International Journal of Highway Engineering
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• v.17 no.5
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• pp.75-82
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• 2015

PURPOSES : In link matching using vehicular trajectory in a car navigation system, it is technically difficult to match the location of the subject vehicle with a link on an electronic map in the vehicle on a grade separation highway segment consisting of an elevated highway and atgrade highway, because of the overlap of geometric lines of the two highways. This study was initiated to propose a link matching algorithm using the characteristics of vehicular movement of the subject vehicle. METHODS : The selected test site is the highway segment between Jeong-reung IC and Gil-eum IC where the Inner Circulation Road and Jeong-reung-ro run together. To evaluate the proposed algorithm, this study collected the raw packet data of vehicles that drove on the test site. In a simulation environment, link matching was performed using an existing algorithm as well as the proposed algorithm. RESULTS: It was clearly found that the characteristics of vehicular movements are different on the two highways. CONCLUSIONS: The proposed algorithm outperformed the existing algorithm.

• International Journal of Highway Engineering
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• v.18 no.1
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• pp.85-90
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• 2016

PURPOSES : The objective of this paper is to understand the deterioration phenomenon and causes in the pavement of a ramp area. METHODS : Ramp areas need to be sloped because of the centrifugal force, which depends on the vehicle speed and grade of the ramp area. As a result, vertical and horizontal forces are applied on the pavement surface of the ramp area. Furthermore, the horizontal force depends on the vehicle speed and grade of the ramp area. In order to analyze the pavement structure of a ramp area, a multi-layered elastic analysis program was used to evaluate the weakest link of fatigue cracking deterioration, according to the simultaneously applied vertical and horizontal forces. RESULTS : From case studies related to the bonding conditions between the surface and base layer in a ramp area, it was found that the partially bonded cases resulted in a critical potential of fatigue cracking deterioration, in a comparison of 50%, 70%, and fully bonded cases. CONCLUSIONS : According to the results of the case studies, the pavement structure system should be reinforced by upgrading the material or increasing the thickness compared to the general pavement areas, in order to provide a performance life similar to the mainline pavements in the ramp areas.

• International Journal of Highway Engineering
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• v.15 no.4
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• pp.177-186
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• 2013

PURPOSES: The purpose of this study theoretically reviews vertical grade deriving process in super high speed environment and compares overseas design criteria with Domestic Standardization also draws suitable vertical grade design criteria of high standard for Domestic Circumstances in Korea. METHODS : By researching domestic vehicle registration status, calculating typical vehicle, using Vissim which is traffic simulation program, Speed-distance curve of the vehicle is derived under each design speed condition. Through Speed-distance curve, estimating critical length of grade and considering critical length of grade, maximum longitudinal incline is proposed. RESULTS : The result of domestic vehicle registration status, the typical vehicle for deriving vertical grade is calculated based on gravity horsepower ratio 200 lb/hp. For calculating critical length of grade, according to change speed of uphill entry, speed-distance curve is derived by using Vissim. Critical length of grade is calculated based on design speed 20 km/h criteria which is point of retardation. Estimated critical length of grade is 808 m and based on this result, maximum longitudinal incline was confirmed in the design speed between 130km/h to 140km/h. CONCLUSIONS: The case of the typical vehicle(truck) which is gravity horsepower ratio 200 lb/hp, maximum longitudinal incline 2% is desirable at the super high speed environment in the design speed between 130km/h to 140km/h.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.361-362
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• 2007

This paper presents the Traffic information system that based on an embedded WinCE board which has GPS and HSDPA. This system is able to overcome the limit of area using the Internet service which other systems can't provide. When the embedded board receives data about the geometric and vehicle speed information, it transmits to the server via HSDPA/the Internet. The server receives and processes it for the path services. And also we present the path guidance algorithm which is based on the speed information. These algorithm responses to the dynamical traffic condition through updating traffic information. Especially, we suggest a Traffic Status Variable in each branch which represents each road's traffic status. This Traffic Status Variable contains speed, road grade; we separate the road three groups as speed limitation; and past speed data - for example, week day rush hour of each road. In addition, the data of cross about left-turn or right-turn can update. Those elements is consisted Traffic Status Variable.