• Journal of Korean Society of Forest Science
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• v.107 no.2
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• pp.166-173
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• 2018

This study was carried out to establish the standard of sub-base facility which can strengthen road surface bearing capacity for smooth passage of logging trucks in forest road as the size of the logging truck has been increased in order to improve the efficiency of timber transportation. The results of reinforcement effect analysis of the surface bearing capacity by the thickness of sub-base prepared with the optimum aggregate mix ratio using geosynthetics for forest road on the soft ground in the Forest Technology and Management Research Center are as follows. The surface bearing capacity of CBR exceeding 15% was found to be sufficient when the sub-base was constructed over 0.2 m depth of laying gravels with installation of geosynthetics after digging out subsoil. However, there is no significant difference in reinforcement effect of surface bearing capacity by types of geosynthetics. And, it was found that the surface bearing capacity was insufficient in the installation of sub-base. Therefore, in the case of soft ground, It is possible to secure the reinforcement of the surface bearing capacity for the smooth passage of heavy logging trucks by sub-base, that was constructed over 0.2 m depth of laying gravels with installation of geosynthetics after digging out subsoil.

• Journal of Korean Society of Forest Science
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• v.89 no.3
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• pp.397-404
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• 2000

This study was carried out to investigate the influence of the road structure and site conditions on side-ditch stability of forest road. For experimental purposes, the forest road in the Kwangrung Experimental Forest, Korea Forestry Research Institute, was chosen as a study site. A total of 556 plots wes set up as every longitudinal gradient changing points by belt-transect method. Data of 10 road structural characteristics and side-ditch stability were collected from each plot and analysed by Quantification II. The main factors in order of partial correlation coefficient were longitudinal gradient, road position, inclination of cut-slope, constituent material of cut-slopes, distance of surface flow, cross-sectional shape of road, pavement material, vegetation of cut-slopes and length of cut-slope. The erosion of side-ditch of forest road occurred in the following cases; more than 8% of the longitudinal gradient, road position of hill under side and foot hill, more than $50^{\circ}$ of inclination of cut-slope, constituent material of cut-slopes of hard soil and gravel soil, more than 80m of distance of surface flow, pavement material with earth or gravel, more than medium covered of vegetation of cut-slopes, and the straight and convex form of road-bed.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.10 no.2
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• pp.34-43
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• 2007

To investigate the restoration procedure on soil physical properties and vegetation at the surface of strip road affected by timber harvesting operation. This study was carried out at strip roads constructed between 1989 and 1994 in Mt. Baekun, Kwangyang, Chollanam-Do. Soil hardness of the surface layer was improved with change of time after strip road construction, but that of 7.6~15 cm depth from the surface was not improved. According to linear regression analysis, it was estimated 16.6 years in 0~7.5 cm and 16.9 years in 7.6~15 cm soil depth to be restored to natural forest lands. The amount of surface soil erosion was 0.045$m^3$/km/yr on strip roads constructed in 1989 and 1990, and road constructed in 1994 showed the highest value (4.5$m^3$/km/yr). Vegetation coverage rates of road surface were 96.7% in strip roads constructed in 1990. Those of cutslope and fillslope were highest in roads constructed in 1990. The results indicated that strip roads were restored with change of time after road construction.

• Korean Journal of Agricultural Science
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• v.45 no.2
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• pp.177-184
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• 2018

The frost heave process from repeated freezing and thawing actions in winter on forest road cut-slopes is important for forest road maintenance and management. This study investigated the damages of the forest heave process on forest road cut-slopes by measuring the changes in the road-cut surface elevation and sediment production and by conducting vegetation surveys which were aimed at providing information for forest road maintenance plans. The temperature and humidity differences were determined between the north and south cut-slopes. T-test showed that the north slope had a lower temperature and humidity than that of the south slope. Field observations also confirmed frozen soils on the north slopes, indicating that the north slopes are susceptible to frost heave. Sediment was converted to dry weight per unit area ($g/m^2$). T-test showed that the north slope produced more sediment than that of the south slope. The study confirmed that more frost heave occurred on the north cut-slopes than on the south cut-slopes. Vegetation surveys were conducted on five cut-slope plots. Considering the dominant species found above the cut-slopes, vegetations in all the plots are expected to succeed to pine and oak in the future. The dominant species appearing on the cut-slopes of the study area were exotic species because the elapsed time of the site was only 2 - 4 years.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.4
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• pp.94-106
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• 2022

In order to increase timber self-sufficiency, Korea's 6th Basic Forest Plan aims to increase the density of forest roads to 12.8 m ha^-1 by 2037. However, due to rapid re-forestation, current management infrastructure is insufficient, with just 4.8 m ha^-1 of forest roads in 2017. This is partly due to time and cost limitations on the process of forest road feasibility evaluation, which considers factors such as topography and forest conditions. To solve this problem, we propose an eco-friendly and efficient forest road network planning method using a geographic information system (GIS), which can evaluate a potential road site remotely based on spatial information. To facilitate such planning, this study identifies forest road construction priorities that can be evaluated using spatial information, such as topography, forest type and forest disasters. A method of predicting the optimal route to connect a forest road with existing roads is also derived. Overlapping analysis was performed using GIS-MCE (which combines GIS with multi-criteria evaluation), targeting the areas of Cheongsong-gun and Buk-gu, Pohang-si, which have a low forest-road density. Each factor affecting the suitability of a proposed new forest road site was assigned a cost, creating a cost surface that facilitates prioritization for each forest type. The forest path's optimal route was then derived using least-cost path analysis. The results of this process were 30 forestry site recommendations in Cheongsong-gun and one in Buk-gu, Pohang-si; this would increase forest road density for the managed forest sites in Cheongsong-gun from 1.58 m ha^-1 to 2.55 m ha^-1. This evaluation method can contribute to the policy of increasing timber self-sufficiency by providing clear guidelines for selecting forest road construction sites and predicting optimal connections to the existing road network.

• Korean Journal of Agricultural Science
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• v.23 no.1
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• pp.138-149
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• 1996

This study was aimed at predicting to running speed related to alignment factors of forest road, and recommending the improvement method of forest road construction using the running speed of vehicles. For these purposes, this study proceeds to select forest roads after reviewing the planning papers and maps, to measure the road alignment factors such as longitudinal gradient, width of roadway, radius of curve, length of curve, superelevation, and conditions of road surface on the subject forest road. It was found that the average running speed of logging truck showed lower value than that of the expected speed of 'Forest Road Construction Regulations and Rules', and the average running speed of loaded truck showed 70-85% of the speed of empty truck. According to the road conditions, speed index (reductive ratio of running speed) was also calculated with respect to radius of curve, longitudinal dradient. The results of the study on the running speed of vehicle subject to the alignment of forest roads make it possible for one to judge the quality of the existed and to be constructed forest roads, to select the structure of forest road to improve the running speed of vehicle on forest road.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.6
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• pp.121-132
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• 2018

Weather is an important factor affecting roadway transportation in many aspects such as traffic flow, driver 's driving patterns, and crashes. This study focuses on the relationship between weather and road surface condition and develops a model to estimate the road surface condition using machine learning. A road surface sensor was attached to the probe vehicle to collect road surface condition classified into three categories as 'dry', 'moist' and 'wet'. Road geometry information (curvature, gradient), traffic information (link speed), weather information (rainfall, humidity, temperature, wind speed) are utilized as variables to estimate the road surface condition. A variety of machine learning algorithms examined for predicting the road surface condition, and a two - stage classification model based on 'Random forest' which has the highest accuracy was constructed. 14 days of data were used to train the model and 2 days of data were used to test the accuracy of the model. As a result, a road surface state prediction model with 81.74% accuracy was constructed. The result of this study shows the possibility of estimating the road surface condition using the existing weather and traffic information without installing new equipment or sensors.

• Journal of Korean Society of Forest Science
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• v.84 no.3
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• pp.319-332
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• 1995

This research was carried out to investigate the influences of forest road characteristics and rainfalls on the amount of erosion on the newly - constructed forest road in the Research Forests of Seoul National University located in Mt. Backwoon - san, Kwangyang. Amount of soil erosion on the newly - constructed forest road was measured for 2 years since the forest road construction. Using the stepwise multiple regression method, amount of soil erosion from cut - slopes, fill - slopes, road surfaces, and side - ditches were seperately expressed as a function of statistically significant road design and rainfall factors, and multiple regression models to estimate the amount of soil erosion were significant to explain the variance in erosion by each structures. According to results of this study, amount of erosion from the newly - constructed forest road was estimated as much as 668.51m/km for 2 years. Out of total amount of soil erosion, 21.9%(144.27m/km) from cut - slopes, 39.8%(261.89m/km) from fill - slopes, 8.1%(53.33m/km) from road surfaces, and 30.2%(199.02m/km) from side - ditches were occurred.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.6
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• pp.51-60
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• 2015

This study conducted shear strength test and plate bearing test to look into the characteristics of bearing capacity using geosynthetics case on forest road surface. The shear strength test showed that the internal friction angle at the time when geosynthetics was used was measured larger on average than that in the unreinforced case. Therefore, using geosynthetics case produced more bearing capacity reinforcement effect. The result from the comparison test of internal friction angle by geosynthetics type revealed that the internal friction angle at the time when geotextile case was used was measured larger. That was attributable to the difference between the area of the total cross section of geotextile made in type of non-woven fabric and its material. Plate bearing test showed that the settlement at the time when geosynthetics was used was measured smaller than that in the unreinforced case. Therefore, using geosynthetics produced more bearing power reinforcement effect. The result from the comparison test showed that geogrid case was measured smaller than geotextile case. Henceforth, It is seemed that it will be necessary to keep studying the reinforcement engineering and process of forest road surface which fits the characteristics and conditions of geosynthetics to prevent forest road demage.

• 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.