• Atmosphere
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• v.17 no.3
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• pp.231-240
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• 2007

The flow regimes of continuously stratified flow over a double mountain and the effects of a double mountain on wave breaking, upstream blocking, and severe downslope windstorms are investigated using a mesoscale numerical model (ARPS). According to the occurrence or non-occurrence of wave breaking and upstream blocking, three different flow regimes are identified over a double mountain. Higher critical Froude numbers are required for wave breaking and upstream blocking initiation for a double mountain than for an isolated mountain. This means that the nonlinearity and blocking effect for a double mountain is larger than that for an isolated mountain. As the separation distance between two mountains decreases, the degree of flow nonlinearity increases, while the blocking effect decreases. A rapid increase of the surface horizontal velocity downwind of each mountain near the critical mountain height for wave breaking initiation indicates that severe downslope windstorms are enhanced by wave breaking. For the flow with wave breaking, the numerically calculated surface drag is much larger than theoretically calculated one because the region with the maximum negative perturbation pressure moves from the top to the downwind slope of each mountain as the internal jump propagating downwind occurs.

• Geomechanics and Engineering
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• v.19 no.1
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• pp.1-9
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• 2019

Shallow failures occur frequently in both engineered and natural slopes in expansive soils. Rainfall infiltration is the most predominant triggering factor that contributes to slope failures in both expansive soils and clayey soils. However, slope failures in expansive soils have some distinct characteristics in comparison to slopes in conventional clayey soils. They typically undergo shallow failures with gentle sliding retrogression characteristics. The shallow sliding mass near the slope surface is typically in a state of unsaturated condition and will exhibit significant volume changes with increasing water content during rainfall periods. Many other properties or characteristics change such as the shear strength, matric suction including stress distribution change with respect to depth and time. All these parameters have a significant contribution to the expansive soil slopes instability and are difficult to take into consideration in slope stability analysis using traditional slope stability analysis methods based on principles of saturated soil mechanics. In this paper, commercial software VADOSE/W that can account for climatic factors is used to predict variation of matric suction with respect to time for an expansive soil cut slope in China, which is reported in the literature. The variation of factor of safety with respect to time for this slope is computed using SLOPE/W by taking account of shear strength reduction associated with loss of matric suction extending state-of-the art understanding of the mechanics of unsaturated soils.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.10 no.5
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• pp.51-57
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• 2007

In order to study the characteristics of vegetation structure in Gundal mountain, we investigated forest community using belt transect method at 30 sites in Gundal mountain. As the result of important value' calculation on over DBH 2cm, Pinus densiflora (56.8), Quercus mongolica (48.5), Pinus rigida(41.4), Castanea crenata (22.3), Quercus variabilis (22.3), Carpinus laxiflora (16.9), Quercus aliena (11.3), Sorbus alnifolia (8.6), and Quercus acutissima (8.5) were in the order of important value. According to the ordination analysis of Gundal mountain forest, Quercus mongolica was found in north face and high of mountain. Carpinus laxiflora was found in north face steep slope and middle of mountain. As DBH analysis, the study community will be dominated by Quercus species. The correlation between the forest community and environment factor could be thought as distinction by soil nutrition etc., but we need more study about environment factors.

• Journal of Environmental Science International
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• v.29 no.5
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• pp.519-529
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• 2020

The purpose of this study was to provide basic health care data for the climate aspects of park re-cultivation by evaluating air ions according to the type of vegetation in the valley and upper slopes of the mountain park. Simple negative or positive air ions were expected to show the same tendencies, so they were analyzed in terms of correcting the air ion index. By analyzing the air ions according to the topography, it was found that valley > slope in terms of the air ion index. When analyzing air ions according to tree species, we found that evergreen conifers in the valley > the deciduous broad-leaved trees in the valley > the evergreen conifers in the slope = the deciduous broad-leaved trees in the slope. For DBH(Diameter at breast height), the valley large pole > slope large pole > slope medium hard wood, while crown density was analyzed as valley dense > slope dense> valley proper > slope proper. Layered structure analysis showed that the multi-layer structure of the valley > multi-layer structure of the slope = the single-layer structure of the valley > the single-layer structure of the slope. The correlation coefficient was determined according to vegetation type and air ion index in the order of DBH > crown density > layer structure > geomorphic structure. In this study, limits exist except for ridge line, valley, and slopes in urban mountain parks. Therefore, analysis should be made considering both topographical structure and various vegetation types in future studies of air ions.

• Korean Journal of Environment and Ecology
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• v.29 no.2
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• pp.184-191
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• 2015

This study aimed to analyze characteristics of the seasonal habitat use of reintroduced Long-tailed Gorals (n=7) in Woraksan (mountain) National Park. We collected 10,721 goral coordinates in Woraksan (mountain) National Park via transmitters, and analyzed habitat use (e.g., aspect, distance from stream and road) from November 2006 to January 2013. Aspect use was southwest (22.6 %), and seasonal aspect use had a southwestern slope (in the spring, summer, and autumn). A northwestern aspect was detected in winter, but slope of $30^{\circ}{\sim}35^{\circ}$ (19.0 %) was used regardless of the season and mean elevation use was 500 m. Moreover, seasonal use was higher in the summer and lower in the winter and spring. The distance from the stream was mainly 50 m in 17.2 %, except in the winter (distance of 300 m), and it was within 50 m in the spring, summer, and autumn. The distance from the road was 100 m in 25.7 %, and seasonal use was within 100 m except for the winter. Thus, we examined significant differences in the habitat use of reintroduced gorals in Woraksan (mountain), and provide elementary data for habitat stabilization of Woraksan (mountain) National Park where goral restoration has advanced.

• Journal of Environmental Science International
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• v.21 no.6
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• pp.725-738
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• 2012

Recently, a variety of GIS-based tools enabling to generate topographic parameters for hydrologic and hydraulic researches have been developed. However, most of GIS-based tools are usually insufficient to estimate and visualize river channel slopes especially along the river network, which can be possibly utilized for many hydraulic equations such as Manning's formula. Many existing GIS-based tools have simply averaged cell-based slopes for the other advanced level of hydrologic units as likely as the mean watershed slope, thus that the river channel slope from the simple approach resulted in the inaccurate channel slope particularly for the mountain region where the slope varies significantly along the downstream direction. The paper aims to provide several more advanced GIS-based methodologies to assess the river channel slopes along the given river network. The developed algorithms were integrated with a newly developed tool named RiverSlope, which adapted theoretical formulas of river hydraulics to calculate channel slopes. For the study area, Han stream in the Jeju island was selected, where the channel slopes have a tendency to rapidly change the upstream near the Halla mountain and sustain the mild slope adjacent to watershed outlet heading for the ocean. The paper compared the simple slope method from the Arc Hydro, with other more complicated methods. The results are discussed to decide better approaches based on the given conditions.

• The Journal of Engineering Geology
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• v.21 no.4
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• pp.281-293
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• 2011

We investigated the causes and characteristics of a landslide at Hwangryeong Mountain, Busan, based on aerial photos, annual precipitation data, rock fracture patterns, and geomorphic features using GIS Software, and a statistical analysis of tilted trees. The analyzed slope shows evidence of a previous slope failure event and the possibility of future failures. Although the NW-SE trending slope was relatively stable until 1975, a large-scale slope failure occurred between 1975 and 1985 due to complex factors, including favorably oriented geologic structures, human activity, and heavy rain. This indicates that a detailed study of geologic structures, slope stability, and rainfall characteristics is important for slope cuttings that could be a major factor and cause of urban landsliding events. The statistic analysis of tilted trees shows a slow progressive creeping type of mass wasting with rock falls oblique to the dip of the slope, with the slope having moved towards the west since 1985. A concentration of tree tilting has developed on the northwestern part of the slope, which could reach critical levels in the future. The analysis of deformed trees is a useful tool for understanding landslides and for predicting and preventing future landslide events.

• Tunnel and Underground Space
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• v.4 no.3
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• pp.215-227
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• 1994

Rock Mass classifications have been developed in many European countries. The most widely used classification methods are the Rock Mass Rating (RMR) system proposed by Bieniawski(1973) and the Q-system developed By Barton et al. (1974). These methods are also adopted at many mountain tunnels and subway sites in our country. Here, a geomechanical classification for slopeds in rock, the "Slope Mass Rating"(SMR) is presented for the preliminary assessment of slope stabiliyt. This method can be applied to excavation and support design in the front part of tunnel and cutting area as a guide line and recommendation on support methods which allow a systemmetic use of geomechanical classification for rock slopes.

• Journal of The Geomorphological Association of Korea
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• v.24 no.1
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• pp.63-76
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• 2017

This research was classified mountain areas with high ecological, environmental and resource value among the macro scaled terrain that can be checked at the space scale of less than 1:1,000,000 and analyzed the topographical characteristics. It has been confirmed that the mountains of the Korean peninsula belong to the groups IV, V, VI(classification by Kapos et al.(2000)) as a result of applying the quantitative standards for designation of mountain areas to the global mountain system. The area of mountains calculated using high resolution DEM is equivalent to 48% of the area of the Korean peninsula, and the result is quite different from the general idea of which 70% is the mountain area of the Korean peninsula. The mountain areas show the distribution of geomorphons, that is different from the plains and the hills and also, it shows the differences between the mountains of the groups IV~ VI classified according to the altitude. As a result of analyzing the relations among type pattern, slope, and relief, specific geomorphons are concentrated at $10^{\circ}$ and $20^{\circ}$ and it shows the possibility to classify the mountainous areas into two groups based on the result that the distribution of landform patterns are bimodal in the relation to the amount of relief.

• Journal of Korean Society of Forest Science
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• v.76 no.2
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• pp.161-168
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• 1987

Forest road (10 Km) constructed for the demonstrational purpose by Forest Work Training Center (F.T.C.) in 1984 was partly damaged through the roadside landside and ditch erosion by the typhoon in 1986. The causes were investigated to apply for protecting against the damage of mountain forest road. The damaging length caused by roadside landside is around 3% out of total length of 10 Km forest road, and mostly coming from the curve road filled up more than 10 m slope length on the concave mountain slope, partly from the foot of fillslope along the ever-following valley and from the both side of fillslope under the outlet of culvert with ever-flowing water. In case of ditch erosion, the big damage at V-type ditch is coming from the overflow of valley water flowing down along the inside slope. Other problem is also showing in the steepness of longitudial gradient, which is felt as a problem in road to be constructed under more than 10 persent of gradient. Other cause of ditch erosion is coming from the bury of sand basin (water collecting wall) by the debris in small diameter culvert zone, namely less than 400mm, in diameter and by the soil mass slumped down from steep wall slope. From above results the causes of F.T.C. model road damage is showing to come from no-following the general guide or little experience to protect against the forest road damage. When improved above mentioned mistakes, F.T.C. Method of mountain forest road type could be developed as a model of Mountain forest road.