• 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 Agricultural Engineers
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• v.64 no.4
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• pp.1-10
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• 2022

A vegetative filter strip (VFS) is one of the best management practices (BMPs) to reduce pollutant loads. This study aims to assess the effectiveness of VFS in dense upland field areas. The study areas are agricultural fields in the Maedae (MD), Gaa (GA), and Jaun (JU) watersheds, where severe sediment yields have occurred and the Korean government has designated them as non-point management regions. The agricultural fields were divided into three or four clusters for each watershed based on their slope, slope length, and area (e.g., MD1, MD2). To assess the sediment trapping (STE) and pesticide reduction efficiency (PRE) of VFS, the Vegetative Filter Strip Modeling System (VFSMOD) was applied with three different scenarios (SC) (SC1: VFS with rye vegetation; SC2: VFS with rye vegetation and a gentle slope in VFS range; and SC3: VFS with grass mixture). For SC1, there were relatively short slope lengths and small areas in the MD1 and GA3 clusters, and they showed higher pollutant reduction (STE>50%, PRE>25%). For SC2 and SC3, all clusters in GA and some clusters (MD1 and MD3) in MD show higher pollutant reduction (>25%), while the uplands in JU still show a lower pollutant (<25%). With correlation analysis between geographic characteristics and VFS effectiveness slope and slope length showed relative higher correlations with the pollutant efficiency than a area. The results of this study implied that slope and slope length should be considered to find suitable upland conditions for VFS installations.

• Journal of Industrial Technology
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• v.21 no.B
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• pp.223-232
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• 2001

This study is finding the most appropriate model of kangwondo watershed. To synthesize each hydrograph, It is found to several parameters which are used in existing hydrographes. then the synthestic hydrograph is compared and investigated with many hydrographes of the rivers in kanwondo. These methods, Nakayasu, Clark, SCS are used to calculate the run-off of this watershed. When the calculated run-off is compared with real rating-curves, then it is found that the SCS method using the Clark's concentrantion time is the best way on this area having large watershed, long river length and gentle water slope, the Nakayasu method is more suitable on this area having small watershed, short river length and steep water slope. Also it is founded from analyzing run-off hydrographes, peak run-off and peak time that the Clark's method applied Kirpich's concentration time way is suitable in the area of kangwondo.

• Journal of the Korean Institute of Rural Architecture
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• v.8 no.1
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• pp.111-120
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• 2006

Our ancestor has accumulated inimitable a building system from experience. and they finally invented Gu-dul that heat the stone as a hitting system. The purpose of this study is to investigate and to write down the on Excavation & Restoration of Traditional Gu-dul in Young-dong. It was found that Gu-dul was the most suited for natural condition. That is wind, direction, earth level. As the results of analyzing the built- technque of traditional Gu- dul : 1) The Gu-dul type is lined, scattered, and mixed. 2) The hight of bank is 25-30cm, 3) The depth of Gaejari is 30-45cm, and The slope of that is gentle. 4) The slope of Gorae(a floor hitter) is 5 - 8%. (from the middle to the edge and from the lower part to the upper part) Therefore, For the practical application of future houses, it will be needed to develop the reasonable hitting system, and suggest to set up Gu-dul for our health and saving energy.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.1 no.1
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• pp.1-7
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• 1989

Theoretical studies have been made to analyze combined refraction diffraction of the wind waves propagating on a large scale current in water of varying depth. The governing equation for monochromatic waves was derived through splitting a mild slope equation into two equations. A numerical model is developed using finite difference scheme which is computationally very efficient for modelling large area. Numerical examples concerning the interactions between waves and rip currents over a gentle slope are presented, in which the current effects on the wave diffraction in the caustic region are closely examined.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.31 no.3 s.52
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• pp.259-263
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• 2005

The aim of the present study is to evaluate relationship between UV-induced MED and perfusion value assessed by Laser Doppler Perfusion Imager. In this study, A increasing linear relationship is seen between perfusion and dose (p<0.05). The dose-response curve show a steep slope in the case of lower MED values group after MED point, For higher MED group, increase with a gentle slope.

• Journal of the Korean association of regional geographers
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• v.15 no.2
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• pp.192-203
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• 2009

The purpose of this paper is to elucidate the formative processes of depositional landforms in Jiwoo drainage basin which located in the most upstream reach of Namgang River. Through the analysis of morphologic characteristics and sedimentary facies, the formative processes can be summarized as follow: First, the high depositional landforms(Sapyeong, Eungam, Naedongdyttle site) were formed by gelifluction process in the periglacial environment during the last glacial period. And the relative height over river bed of them is getting lower from upper to downstream. The extent of the high depositional landforms is assumed about 1 kilometer downstream far from the confluence of Jiwoo stream and Namgang River. Second, the sediments in the gentle slope at Jangseungbuldle were carried by gelifluction process during the last glacial stage after the deep-weathered bedrock had formed a gentle slope. Third, the high depositional landforms were dissected during warm and humid environment of postglacial stage, and some sediments of them were left in the river bed. Later, as the more upstream high depositional landforms were dissected completely, stream power was getting more than resistance(sediment storage) and the low depositional landforms(Sapyeong, Yongchusa, Deungbangdle site) were formed.

• Ocean and Polar Research
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• v.26 no.2
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• pp.207-218
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• 2004

Lomilik Seamount in the west Pacific was seismically surveyed and photographed to illuminate the bottom topography, the condition of manganese crust, and the characteristics of sedimentary environment. Lomilik Seamount has a NW-SE elongated bottom topography with steep slopes in the NESW direction part. Even though the steep slopes of the seamount are devoid of deposits, the summit area and gentle slope of the seamount are covered with thick deposits. The seismic data indicate that Lomilik Seamount is a flat-topped and step-faulted guyot of volcanic origin. Deep-sea camera photographs show that much of the seafloor is rippled in symmetrical and asymmetrical patterns. The traces of biological activity were distinct on gentle seafloor suggesting the low-energy bottom conditions. Some photographs also show outcrops encrusted with manganese crusts. Sedimentary environments in the Lomilik Seamount appear have been governed by regional morphology and strong bottom current.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.168-172
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• 2012

This paper is focusing on the comparison of different kinds of BPFs(Band Pass Filters) passing signals with a particular frequency band. According to the different classifications, features and target application systems, BPF has many types. Chebyshev filter which has a steep slope and a few ripples, and Butterworth filter which has no ripple but gentle slope are the most typical BPFs. The ideal filter is flat in the passband and the slope in the transition band is perpendicular. In this paper, we suggest the cascading Chebyshev BPF with the advantages of the Chebyshev filter and the Butterworth filter simultaneously to make a closest filter to an ideal filter. The proposing BPF is the tenth Chebyshev BPF cascading the fourth and the sixth, and it is designed as the tenth cascading Chebyshev BPF. To measure the performance of the designing filter, we have compared and analyzed the tenth Chebyshev filter with the tenth Butterworth filter. As a result, the tenth cascading Chebyshev BPF has decreased the ripple more than 1/4 [dB] in the passband. Finally, the output of the simulation showed the validity of the proposing cascading Chebyshev filter.

• Journal of Korea Water Resources Association
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• v.46 no.5
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• pp.559-568
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• 2013

Surface compaction significantly impacts runoff and soil erosion under rainfall since it leads to changes of soil physical characteristics such as increase of bulk density and shear stress, change of microporosity, and decrease of hydraulic conductivity. This study addressed surface compaction effects on runoff and soil loss from bare and disturbed soils that are commonly distributed on construction sites. Thirty-six rainfall simulations from three replicates of each involving rainfall intensities (68.5 mm/hr, 95.6 mm/hr) and plot gradients ($5^{\circ}$, $12.5^{\circ}$, $20^{\circ}$) were conducted to measure runoff and soil loss for two different soil surface treatments (compacted surface, non-compacted surface). Compacted surface increased significantly soil bulk density and soil strength. However, the effect of surface treatments on runoff changed with rainfall intensity and plot gradient. Rainfall intensity and plot gradient had a positive effect on mean soil loss. In addition, the effect of surface treatments on soil loss responded differently with rainfall intensity and plot gradient. Compacted surfaces increased soil loss at gentle slope ($5^{\circ}$) while they decreased soil loss at steep slope ($20^{\circ}$). These results indicate that there exists transitional slope range ($10{\sim}15^{\circ}$) between gentle and steep slope by surface compaction effects on soil loss under disturbed bare soils and simulated rainfalls.