• Korean Journal of Agricultural and Forest Meteorology
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• 제11권4호
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• pp.151-161
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• 2009

Configuration of soil hydraulic property is an essential component to understand the hydrological processes at the hillslope scale. In this study, we investigated temporal variations in pore development and soil hydraulic properties during the period from March to October in 2008. Characteristics for macropore flow and hydraulic conductivity were measured at two hillslopes: one is the hillslope located at the Buprunsa in Sulmachun watershed, and the other is the hillslope located in Gwangneung Research Forest. Vertical fluxes through macropore were measured using a tension infiltrometer at the depth of surface. The saturated hydraulic conductivities in March, June, July and September were relatively high compared to those in May and October. Temporal variations in several soil hydraulic features could be explained by the differences in vegetation activity and soil moisture content determined by antecedent precipitation. Particularly, the features of macropores had a substantial impact on hydraulic conductivity in the forest hillslope. The temporal nonuniformity of the soil hydraulic properties observed in this study manifests the dynamic features of hydrological processes in the hillslope scale and the experimental results will be useful to understand the internal hydrological processes in the mountainous hillslope.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• 제6권4호
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• pp.242-248
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• 2001

A high resolution Chirp seismic profile and a multichannel seismic reflection profile were analysed to study the possibility of gas hydrate presence in the southwestern upper slope of the Ulleung Basin. The Chirp profile shows acoustic turbidity, acoustic void, and pockmarks, suggesting the presence of shallow gas in the sediments .Slope failures appear to have occurred in association with decomposition of gas hydrated sediments. A bottom-simulating reflector (BSR) is seen in subbottom depths of 60 to 110 m below the seafloor at water depths of 750 to 1130 m. The sediments above BSR are characterized by acoustic blanking probably due to amplitude reduction caused by a mixture of gas hydrate with sediments. The interval velocity above the BSR is 1,650 m/sec and it drops abruptly to 1,080 m/sec below the BSR. The sediment column between seafloor and the BSR thins with increasing water depth, which is very closely related to increasing geothermal gradient with increasing water depth in the Ulleung Basin.

• Journal of the Korean Geotechnical Society
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• 제23권6호
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• pp.97-102
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• 2007

Though the stability analysis of soil slopes widely employs the limit equilibrium method, the study on the jointed rock slopes must consider the direction of joint and the characteristics of Joint at the same time. This study analyzes the result of the change in the factors which show the characteristics of discontinuity and the shape factor of rock slopes, and so on, in an attempt to validate the propriety as to the interpretation of jointed rock slope stability which uses the general finite element program. First, the difference depending on the flow rules was compared, and the factor effect study was conducted. The selected independent variables included the direction of joint which displays the mechanical characteristics of discontinuity, adhesive cohesion, friction angle, the inclination and height of rock slope which reveal the shape of slope and surcharge load. And the horizontal displacement was numerically interpreted at the 1/3 point below the slope, a dependent variable, to compare the relative degree of factor effects. The findings of study on factor effects led to the validation that the result of horizontal displacement for each factor satisfied various engineering characteristics, making it possible to be applied to stability interpretation of jointed rock slope. A modelling is possible, which considers the application of the result of real geotechnical surveys & laboratory studies and the non-linear characteristics when designing the rock slope. In addition, the stress change which may result from the natural disaster, such as precipitation, and the construction, can be expressed. Furthermore, as the complicated rock condition and the ground supporting effect can be considered through FEM, it is considered to be very useful in making an engineering decision on the cut-slope, reinforcement and so on.

• Journal of the Korean Geographical Society
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• 제46권6호
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• pp.673-692
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• 2011

Advances in computer technology have enabled us to develop and use numerical landscape evolution models (NLEMs) for exploring the dynamics of geomorphic system from a variety of viewpoints which previously could have not been taken. However, as of yet there have been no trials using or developing NLEMs in Korea. The purpose of this research is to develop a 2 dimensional NLEM on a geological time scale and evaluate its usefulness. The newly developed NLEM (ND-NLEM) treats bedrock weathering as one of the major geomorphic processes and attempts to simulate the thickness of soil. As such it is possible to model the weathering-limited as well as the transport-limited environment on hillslopes. Moreover the ND-NLEM includes not only slow and continuous mass transport like soil creep, but also rapid and discrete mass transport like landslides. Bedrock incision is simulated in the ND-NLEM where fluvial transport capacity is large enough to move all channel bed loads, such that ND-NLEM can model the detachment-limited environment. Furthermore the ND-NLEM adopts the D-infinity algorithm when routing flows in the model domain, so it reduces distortion due to the use of the steepest descent slope flow direction algorithm. In the experiments to evaluate the usefulness of the ND-NLEM, characteristics of the channel network observed from the model results were similar to those of the case study area for comparison, and the hypsometry curve log during the experiment showed rational evidence of landscape evolution. Therefore, the ND-NLEM is shown to be useful for simulating landscape evolution on a geological time scale.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• 제9권1호
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• pp.1-12
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• 2004

Sedimentary facies and high-resolution echo facies were analyzed to elucidate sedimentation pattern of the late Quaternary glacial-marine deposits in the northern continental margin of the South Shetland Islands. Six sedimentary facies are classified, based on grain texture and sedimentary structures in gravity cores. The high-resolution (3.5 ㎑) echo characters are classified into 6 echo facies on the basis of clarity, continuity, and shape of bottom and subbottom echoes together with seafloor topography. Distribution of the echo and sedimentary facies suggest that there was a significant change in sedimentation pattern between the Last Glacial Maximum (LGM) and subsequent glacier-retreating period. When the grounded glaciers extended to the present shelfbreak during LGM, coarse-grained subglacial tills were widespread in the shelf area, and deep troughs in the shelf were carved beneath the fast-flowing ice steam. As the glacial margin retreated landward after LGM, dense meltwater plumes released from the retreating ice-front were funneled along the glacier-carved troughs, and accumulated channel- or cannyon-fill deposits in the shelf and the upper to mid slope. At that time, slope sediments seem to have been reworked by slope failures and unsteady contour currents, and further transported by fine-grained turbidity currents along the South Shetland Trench. After the glacial retreat, sediments in the shelf and slope areas have been mainly introduced by persistent (hemi) pelagic settling, and fine-grained turbidity currents frequently occur along the axis of the South Shetland Trench.

• Journal of the Speleological Society of Korea
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• 제67호
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• pp.43-51
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• 2005

This study on Gobongdond Wetlands have hydrogeomorpholosic charateristics in the southern-west of Gogongsan. This study area have been dissected and deep weathered. in geology, this area show banded gneiss consisting of alternated felsis and mafic layers. in geomorphology this area have 3 slope that surplyed the surface water and ground water, but have a little water source by surface water. The most of Gobongdong wetland's water sources are aquifer or confined aquifer, so this wetlands have many seepages or discharges. The characteristics of Soil have retained the wetland's water. Deep weathering made the parents soil into clay minerals.(siallitization) This clay minerals have a high water table.

• The Journal of Engineering Geology
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• 제20권1호
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• pp.101-109
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• 2010

There are many slopes generally developed by excavation and cut slope with small steps on massive slopes of roads. Especially these cut slopes which excavating around fault fracture zone need a reinforcement technology in order to ensure safety. In the case of slope excavation, it is difficult to use the existing slope support at fracture zone because of geological characteristics. Especially the factor of safety decreases significantly due to the movement of blocks in bed rocks and the expansion of interspace of discontinuous planes in fractured zones caused by excavation. Thus an efficient reinforcement technique in accordance with geological properties of fracture zones needs to be developed because the existing slope support has a restricted application. Therefore it is necessary to develop the specialized rock bolt technique in order to ensure an efficient factor of safety for anomalous fracture zones in slopes and tunnels. The purpose of this study is to develop newly improved rock bolt to increase a supporting effect of the swellex bolt method used recently as a friction type in fracture zones.

• Korean Journal of Agricultural and Forest Meteorology
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• 제18권2호
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• pp.88-98
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• 2016

The storage variation in the vadose zone at a hillslope is important to understand the hydrological process. This study explores seasonal changes of soil water storage at a hillslope scale. The study was conducted on a hillslope of Beomrunsa, located in the Seolma-cheon river basin in Paju-si, Gyeonggi-do. Using soil moisture measurements through Time Domain Reflectometry (TDR), storage, discharge, and response constant were calculated for all monitoring points on a hillslope between March and November, 2010. This study found that temporal changes in storage are resulted from the rainfall distribution patterns. Analysis of the spatial changes in storage indicated that the soil water storage tends to increase towards the downslope direction. The discharges calculated based on the soil water measurements exhibited a high correlation with observation discharge. The storage response constant was high during the autumn which demonstrates the increased contribution from upslope is responsible for the occurrence of soil water recharge during autumn.

• Journal of the Korean Geotechnical Society
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• 제21권5호
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• pp.93-101
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• 2005

The formation of slopes is unavoidable under the special circumstance of Korea where $7%$ of the whole area are composed of mountains and civil engineering projects such as road and site developments are increasing with industrial development and horizontal expansions of urban area. Stability of slopes is one of quite important issues under special meteorological characteristics that over two-thirds of annual average rainfall is concentrated in summer season and the localized torrential downpour is getting more frequent recently. As a result of these circumstances, partial slope failures by debris flow of the high water content soils occur frequently in cut soil slopes. In this case of debris flow slope failure, slope declination method is selected fur the stable recovery because it is impossible to recover entirely by existing recovery methods. Seeding or special grass planting methods are followed separately without exception. The method by which entire recover with bigger stability ratio would be possible and grass planting work would be done simultaneously is developed. For debris flow failure slopes, this study secured the safety of slopes by preventing the inflow of rainwater and scour using geosynthetics-reinforced embankment, and created nature-friendly slopes by planting trees on the slopes.

• Journal of Korea Water Resources Association
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• 제32권1호
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• pp.83-94
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• 1999

In continental margins, turbid underflows which are not confined to a given channel, are free to spread laterally as well as longitudinally. Lateral spreading can reduce substantially the run out distance of flows along continental shelves and slopes. Laboratory experiments with a large tank, employing saline density currents as surrogates for fine-grained turbidity flow, coupled with dimensional analysis, have been used to develop a simple expression for lateral spreading rates of two-dimensional flows on sloping beds. characteristic length and time are determined by the flow discharge and buoyancy flux at the inlet. By knowing the initial width of the flow, the spreading law can be used to estimate the maximum width of the current at different times as well as the longitudinal spreading rate. Predictions for flows compare favorably against observations.