• Journal of Environmental Science International
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• v.21 no.3
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• pp.297-303
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• 2012

Slope is the geographic factor reflecting the 3-dimensional features of basin and it can be considered as the important geomorphological factor which governs the morphology of basin and the dynamics of water movement. In this study the approach to the 3-dimensional structures of basin is attempted with statistical analysis of local slope which can be defined and measured in easy and objective manner by means of DEM. As a result local slope is confirmed to be a highly variable spatial factor in basin. And distribution map of local slope based on spatial autocorrelation length in this study would be a useful tool in the further research of hydrology and geomorphology.

• Ocean and Polar Research
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• v.32 no.3
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• pp.309-319
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• 2010

To assess community structure and diversity of archaea, a clone sequencing analysis based on an archaeal 16S rRNA gene was conducted at three sediment depths of the continental slope and Ulleung Basin in the East Sea. A total of 311 and 342 clones were sequenced at the slope and basin sites, respectively. Marine Group I, which is known as the ammonia oxidizers, appeared to predominate in the surface sediment of both sites (97.3% at slope, 88.5% at basin). In the anoxic subsurface sediment of the slope and basin, the predominant archaeal group differed noticeably. Marine Benthic Group B dominated in the subsurface sediment of the slope. Marine Benthic Group D and Miscellaneous Crenarchaeotal Group were the second largest archaeal group at 8-9 cm and 18-19 cm depth, respectively. Marine Benthic Group C of Crenarchaeota occupied the highest proportion by accounting for more than 60% of total clones in the subsurface sediments of the basin site. While archaeal groups that use metal oxide as an electron acceptor were relatively more abundant at the basin sites with manganese (Mn) oxide-enriched surface sediment, archaeal groups related to the sulfur cycle were more abundant in the sulfidogenic sediments of the slope. Overall results indicate that archaeal communities in the Ulleung Basin show clear spatial variation with depth and sites according to geochemical properties the sediment. Archaeal communities also seem to play a significant role in the biogeochemical carbon (C), nitrogen (N), sulfur (S), and metal cycles at each site.

• Journal of Environmental Science International
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• v.9 no.1
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• pp.13-18
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• 2000

The purpose of this study is to estimate the low-flow statistics at the mountainous watershed. The formulation for the estimation of the design low-flow statistics was obtained by means of a hydraulic approach applied to a simple conceptual model for a mountainous watershed. Three of the independent variables associated with the low-flow statistics is watershed area(A), average basin slope(S) and the base flow recession constant(K); Watershed area was measured from topographic maps and average basin slope is approximated in this study using Strahler's slope determining method. And base flow recession constant computed using Vogel and Kroll's method. Unfortunately, this method is usually unavailable at ungaged sites. In this study, recession constant at ungaged sites is estimated using graphical regression method used by Giese and Mason. The model for estimating low-flow statistics were applied to all 61 catchments in the Sumjin, Mankyung basin.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.11b
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• pp.103-114
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• 2002

Stability of cut-slope is considered to have a deep relationship with rock types since rock has its own engineering and geological characteristic such as shear strength, durability, weathering profile, geological structures. Therefore, analysis of geological and engineering characterisics of rock mass is essential for the evaluation of rock slope stability This paper introduces the statistical data of slope failure cases which was collected from highway slopes constructed in sedimentary rock mainly of shale in Ky ng-sang Basin. Primary failure feature in this area is planar failure along the bedding regardless of slope geometry. Even a disasterous slope failure case due to the thick clay layer between the beddings was reported. Failures and rock fall were reported to ocurred frequently after the completion of cutting due to the weathering, so long-term slope stability should be considered as a important factors in design.

• Economic and Environmental Geology
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• v.50 no.2
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• pp.129-143
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• 2017

The shallow sediments in the southwestern Ulleung Basin consist of mass flow deposits such as slide/slump and debris flow deposits (DFD), caused by slope failure. These sediments are proven to be important in studying geological disaster and stability of the seafloor. In this paper, we analysised the flow accumulation and slope failure susceptibility of the Ulleung Basin on the basis of multi-beam data, collected in this area. We also studied the distribution pattern and the seismic characteristics of the DFD in the uppermost layer of the Ulleung Basin on the basis of seismic data. The slope susceptibility was calculated as the frequency ratio of each factors including slope, aspect, curvature and stream power index (SPI), which causes the slope failure. These results indicate that the slope failure is frequently to occur in the southern and western continental slope of the Ulleung Basin. The sediment flow (mass flow) caused by the slope failure converges to the north and northwest of the Ulleung Basin. According to the seismic characteristics, the uppermost layer in study area can be divided into four sedimentary unit. These sedimentary units develop from the south and southwest to the north and northwest in association with slope susceptibility and flow accumulation.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.107-112
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• 2005

Road is built continuously along with development of industry and cut slope is happened necessarily in road construction. Geoengineers are executing cut slope stability analysis considering various cut slope condition such as topography, geology, hydraulic condition and so on. The Tertiary Jungja Basin is located in the southeastern coastal area of the Korea Peninsula. Jungja Basin area is created by geotectonic movement of the plate after Early Miocene epoch. The northwestern and southwestern boundary of the basin is fault zone. The Basement rock is hornfels (Ulsan Formation). Basin-fills consist of extrusive volcanic rock(Tangsa Andesites), unconsolidated fluviatile conglomerate(Kangdong Formation) and shallow brackish-water sandstone(Sinhyun Formation). The characteristics of cut slopes in this area is different with cut slopes in the other site. Soil layers in this area is unconsolidated sediments and is not formed the weathering and erosion of the rock. So, the depth of soil layer is very thick. Faults of this area are northwest-southeast and northeast-southwest direction. Expandible clay mineral as smectite, chlorite et al. detected from fault gouge using XRD. Therefore, Jungja Basin area must consider the characteristics of the faults and soil layers thickness necessarily cut slopes stability analysis.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.339-346
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• 1999

The stability of rock slope is considered to have a deep relation with types of rocks because types of rocks have their own typical weathering profiles, geological structures and characteristics of failures. Therefore it is essential for the evaluation of rock slope stability to analyze geological and engineering characteristics in rock mass. The data which collected from investigated slopes in sedimentary rock of Kyengsang Basin along highways were analyzed. Primary factors affecting slope stability in rock mass are: dips and strikes of slopes and discontinuities, shear strength of discontinuities, slope geometry and geological structures etc.

• Ocean and Polar Research
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• v.32 no.3
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• pp.299-307
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• 2010

In conjunction with geochemical characteristics, rate of sulfate reduction was investigated at two sediment sites in the continental slope and rise (basin) of the Ulleung Basin in the East Sea. Geochemical sediment analysis revealed that the surface sediments of the basin site (D2) were enriched with manganese oxides (348 ${\mu}mol$ $cm^{-3}$) and iron oxides (133 ${\mu}mol$ $cm^{-3}$), whereas total reduced sulfur (TRS) in the solid phase was nearly depleted. Sulfate reduction rates (SRRs) ranged from 20.96 to 92.87 nmol $cm^{-3}$ $d^{-1}$ at the slope site (M1) and from 0.65 to 22.32 nmol $cm^{-3}$ $d^{-1}$ at the basin site (D2). Depth integrated SRR within the top 10 cm depth of the slope site (M1; 5.25 mmol $m^{-2}$ $d^{-1}$) was approximately 6 times higher than that at the basin site (D2; 0.94 mmol $m^{-2}$ $d^{-1}$) despite high organic content (>2.0% dry wt.) in the sediment of both sites. The results indicate that the spatial variations of sulfate reduction are affected by the distribution of manganese oxide and iron oxide-enriched surface sediment of the Ulleung Basin.

• Journal of the Korean Geographical Society
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• v.40
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• pp.15-29
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• 1989

The purpose of this study is to analyze the Slope Angles and Summit Levels in the relation with the geological structures in the Taehwa River Basii where the NNE-SSW trending Yangsan fault and subsiduary fault are well developed. The mean slope angle in the Taehwa river basin is 12.18$^{\circ}$. The mean slope is higher in the volcanic and metamorphic terrain than in the area of granitic and sedimentary rocks. In view of a slope angle, the area can be divided into four categories, that is, low plains (0-5$^{\circ}$), hilly gentle slopes (5-15$^{\circ}$), moderate steep mountain slope (15-25$^{\circ}$), and steep mountain slope (over 25$^{\circ}$). The analysis of summit level exhibits that the mean of the highest points in the Taehwa River Basin composed mainly of the volcanic and metamorphic rocks is 327m.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1306-1310
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• 2009

The roughness coefficients were estimated by the Manning's equation for the measured stage and flow velocity of Bocheong stream basin in Kum river. The relationships between the estimated roughness coefficients and the geomorphologic factors were formulated by the linear, logarithmic, exponential and power type function, thereafter correlation equations were presented. The correlation analysis was performed between the measured stream length and the basin area of Bocheong stream basin by the linear, logarithmic, exponential and power type function, and correlation equation for the stream length was given. The roughness coefficient has strong correlationship with stream slope, but low correlation coefficients with stream length and basin area. For the correlationship with the roughness coefficients and the stream slope, the logarithmic type function has the smallest correlation coefficient, on the other hand, the exponential type function has the largest correlation coefficient. For the relationship between the stream length and the basin area, the correlation coefficient of the logarithmic type function shows the smallest value, linear type function shows the largest value.