• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.338-340
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• 2009

The asphalt pavement is usually non-uniform since achieving a non-segregated and homogeneous asphalt mixture is very difficult. The segregation can occur in the mixed material before it is fed onto the road and it become segregated as it is being placed onto the road surface. Note that this segregation determines the performance of the asphalt pavement. Hence, it is necessary to check the segregation by estimating the density of the asphalt pavement in the field. In this paper, a research on estimating the density of the asphalt mixture by measuring the dielectric constant of the material is conducted. An RF transceiver and an antenna are designed and tested to a series of asphalt density samples, and discussions are shown.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.277-282
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• 2006

Road traffic noise is not produced by any one factor rather occurs as a composition of various factors. Its occurrence is made by running engine noise, tire frictional, and exhaust noise etc. The quality of the noise depends on the size of the vehicles, rotation and engine speed, vehicle load, package state of the road and incline etc. The occurrence of noise level of heavy trucks appears louder than smaller vehicles and the noise levels produced differs according to speed and load etc between similar size vehicles. Other factors such as traffic density, average speed, mixing rate of heavy vehicles, and the distance between vehicles also generate road traffic noise. In this paper we examine 2, 4, and 6-lane roads in Jeonju. Consequently, this study examined the means used to measure road traffic noise. It was found that when there is a large traffic density and the average velocity is below 70 km/hr, the noise level could receive a relative proper value by the current measuring means. But in the case of night-time, it was found that the current measuring method is inapposite.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.3
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• pp.266-271
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• 2009

Electronic equipments and a missile carried by heavy trucks are often subjected to vibration and shock excitation during their transportation. Electronic equipments are so vulnerable to vibration and shock input that it is necessary to know in advance the vibration level of the truck which cause the damage of equipments. Road tests of a heavy truck carrying a canister on different road conditions such as paved road, unpaved road, and washboard are performed and the effect of road conditions on the vibration characteristics are analyzed. Vibration levels were measured at various locations of the truck along the path through which vibration was transmitted. This study reveals that the velocity of the truck as well as the road surface conditions are main factors which affect the vibration levels of the truck. The power spectrum density of the measured vibration signal and the factors affecting the PSD are also analyzed in this paper.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1836-1842
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• 2015

On road networks, the clustering of moving objects is important for traffic monitoring and routes recommendation. The existing schemes find out density route by considering the number of vehicles in a road segment. Since they don’t consider the features of each road segment such as width, length, and directions in a road network, the results are not correct in some real road networks. To overcome such problems, we propose a clustering method for congested routes discovering from the trajectories of moving objects on road networks. The proposed scheme can be divided into three steps. First, it divides each road network into segments with different width, length, and directions. Second, the congested road segments are detected through analyzing the trajectories of moving objects on the road network. The saturation degree of each road segment and the average moving speed of vehicles in a road segment are computed to detect the congested road segments. Finally, we compute the final congested routes by using a clustering scheme. The experimental results showed that the proposed scheme can efficiently discover the congested routes in different directions of the roads.

• Wind and Structures
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• v.6 no.5
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• pp.325-346
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• 2003

High-sided road vehicles are susceptible to a sharp-edged crosswind gust, which may cause vehicle accidents such as overturning, excessive sideslip, or exaggerated rotation. This paper thus investigates the dynamic behaviour and possible accidents of high-sided road vehicles entering a sharp-edged crosswind gust with road surface roughness and vehicle suspension included. The high-sided road vehicle is modelled as a combination of several rigid bodies connected by a series of springs and dampers in both vertical and lateral directions. The random roughness of road surface is generated from power spectral density functions for various road conditions. The empirical formulae derived from wind tunnel test results are employed to determine aerodynamic forces and moments acting on the vehicle. After the governing equations of motion are established, an extensive computation work is performed to examine the effects of road surface roughness and vehicle suspension on the dynamic behaviour and vehicle accidents. It is demonstrated that for the high-sided road vehicle and wind forces specified in the computation, the accident vehicle speed of the road vehicle running on the road of average condition is relatively smaller than that running on the road of very good condition for a given crosswind gust. The vehicle suspension system should be taken into consideration, and the accident vehicle speed becomes smaller if the vehicle suspension system has softer springs and lighter dampers.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.1 no.1
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• pp.18-27
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• 1998

To investigate the restoration progression on soil physical properties and vegetation at the surface of logging road affected by timber harvesting operation. This study was carried out at logging roads constructed from 1989 to 1994 in Mt. Baekwoon, Kwangyang, Chollanam-do. Judging from the analysis of soil hardness, there were significant changes in the depth of soil between 5 and 10cm. Soil hardness was recovered from the compacted condition to the natural forest condition after 9 years passed. Soil macroporous ratio (pF2.7) of topsoil was higher than that of deep soil. Soil moisture retention of topsoil was more improved than that of deep soil. From the view of soil bulk density, the necessary time for recovering to the undisturbed condition of forest soil was about 10 years in the logging road left. Soil physical properties such as soil bulk density and porous ratio were recovered as time passed. Improved soil physical properties promoted the plant recovery on the logging road surface. The dominant species on the logging roads were Comus kousa, Prunus sargentii as overstory species, Rubus crataegifolius, Lespedeza bicolor as understory species, and Saussurea gracilis, Pteridium aquilinum var. latiusculum as herbaceous species. The plant recovery of bank-slopes was faster than that of cut-slopes and road surface. In progress of year, average plant coverage were 70 to 90% in cut- and bank-slopes and 30 to 60% on the logging road, surface which was elapsed 9 years after logging road construction. Therefore, additional planting and seeding work could be effective to the soil condition and vegetation restoration.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.571-577
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• 2018

A gyratory compactor was developed to reflect the field compaction roller, which is commonly used in road construction. Unlike the compaction of the proctor using a conventional impact load, the gyratory compactor simulated the field roller compaction characteristics using the compressive force by the roller weight and the shear force through the rotation of a roller. The purpose of this study was to evaluate the shear stress and density change characteristics during compaction, which are difficult to obtain in the existing compaction process of the proctor, and to utilize it as a basic data for road design. The compaction characteristics of sand and subgrade soils were also analyzed and evaluated using the gyratory compactor. The compaction characteristics obtained using the gyratory compaction are basically the number of gyrations, height of the specimen, compaction density, void ratio, degree of saturation, and shear stress. As the number of gyrations increased, the height of the specimen decreased, the compaction density increased, the void ratio decreased, the degree of saturation increased, and the shear stress tended to increase. The shear stress of the compacted specimens started at 200 kPa in the initial stage of compaction and increased to approximately 330 to 350 kPa at 50 gyrations. The compaction density, degree of saturation and shear stress tended to increase with increasing water content in the same specimens. Compaction using turning compaction has the advantage of measuring the physical properties required for road design, such as density and shear stress, so that more engineering road design will be possible if it is reflected in road design.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.424-429
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• 2013

The trolley carrying the pod moves along by the airfield runway. The pod through the trolley are subjected to vibration arising from the ground state, the precision optical components in the pod can have a significant impact. The road tests were conducted by using the measurement pod to remove the risk for the project. The measurement pod was composed with the ACRA, sensors, battery. The accelerometers were attached to get the acceleration through the road condition. The PSD envelop was calculated by FFT from the acceleration. The driving safety was proven through comparing the measurement data and MIL-STD-810G specification.

• Journal of Korean Society of Forest Science
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• v.83 no.4
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• pp.545-555
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• 1994

The objective of the study was to provide the useful scientific data on the early rehabilitation of the legging road after timber harvesting in the forest area. This study was carried out at logging roads which were constructed during 1989 and 1994 in Mt. Baekwoon. The field survey was conducted in July, 1991. Judging from the analysis of soil bulk density, time required for recovery as the undisturbed forest soil condition was more than 10 years in the road which was left, and the regression equation is as follows, $$Y_1=1.4195-0.0744{\cdot}X(R^2=0.91)$$ $$Y_2=1.4673-0.0688{\cdot}X(R^2=0.73)$$ (X : elapsed year after road construction. $Y_1$, $Y_2$ : soil bulk density($g/cm^3$) at 0~7.5cm, and 7.5~15.0cm, respectively) Especially soil bulk density with buffer strip-woods was $0.890-0.903g/cm^3$, so it was 20% lower than that of logging road surface without buffer strip-woods. Among the 7 factors, location, sand content, and soil hardness had statistically significant effect on the soil bulk density in logging road surface. The pioneer species on logging road surface were Rhus cratargifolius, Prunus chinensis, and Lespedeza cyrtobotrya, etc. in woody species, and Pteridium aquilinum, Arundinella hirta, and Lysimachia clethroides, etc. in herb species. So, in process of year, average plant coverage were 70% on cutting and banking slope and 20% on logging road surface which elapsed 6 years after logging road construction. Through this research, buffer strip-woods must be remained for environmental conservation of forest conditions, and from the time to be closed the road, planting, seeding, and grazing works could be effective to the soil condition and vegetation recovery.

• Journal of the Korean Institute of Landscape Architecture
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• v.35 no.6
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• pp.37-47
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• 2008

Recently, reckless exploitation of land resources without much consideration for the environmental value of the land has been witnessed to accommodate the ever-increasing demands for regional development. Fragmentation due to land development is a major reason for the declining biodiversity in forest ecosystems. The purposes of this study were (1) to investigate the relationship between the factors of land development and forest fragmentation in 13 watersheds of a metropolitan area and (2) to suggest a forest management plan through the relationship. We carried out a factor analysis to determine explanatory axes of forest fragmentation, and then conducted a correlation analysis between the factor scores and the factor of land development, such as the rate of built-up areas, road density, number of built-up patches, and area of housing developments. The first explanatory axis represented stability of landscape highly related with the rate of the built-up area and road density. The second axis represented the level of fragment highly related with a number of built-up patches. Forest fragmentation patterns of the 13 watersheds were classified for the similarity in forest fragmentation. This study presents the forest management plans including distribution and level of land development and forest conservation.