• Title/Summary/Keyword: Multi-layer Soil

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Evaluation of Average Shear-wave Velocity Estimation Methods of Multi-layered Strata Considering Site Period (지반주기를 고려한 다층지반의 평균전단파속도 추정 방법 평가)

  • Kim, Dong-Kwan
    • Journal of the Earthquake Engineering Society of Korea
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    • v.23 no.3
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    • pp.191-199
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    • 2019
  • To calculate proper seismic design load and seismic design category, the exact site class for construction site is required. At present, the average shear-wave velocity for multi-layer soil deposits is calculated by the sum of shear-wave velocities without considering of vertical relationship of the strata. In this study, the transfer function for the multi-layered soil deposits was reviewed on the basis of the wave propagation theory. Also, the transfer function was accurately verified by the finite element model and the eigenvalue analysis. Three methods for site period estimation were evaluated. The sum of shear-wave velocities underestimated the average shear-wave velocities of 526 strata with large deviations. The equation of Mexican code overestimated the average shear-wave velocities. The equation of Japanese code well estimated the average shear-wave velocities with small deviation.

A Multi-Layer Perceptron for Color Index based Vegetation Segmentation (색상지수 기반의 식물분할을 위한 다층퍼셉트론 신경망)

  • Lee, Moon-Kyu
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.43 no.1
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    • pp.16-25
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    • 2020
  • Vegetation segmentation in a field color image is a process of distinguishing vegetation objects of interests like crops and weeds from a background of soil and/or other residues. The performance of the process is crucial in automatic precision agriculture which includes weed control and crop status monitoring. To facilitate the segmentation, color indices have predominantly been used to transform the color image into its gray-scale image. A thresholding technique like the Otsu method is then applied to distinguish vegetation parts from the background. An obvious demerit of the thresholding based segmentation will be that classification of each pixel into vegetation or background is carried out solely by using the color feature of the pixel itself without taking into account color features of its neighboring pixels. This paper presents a new pixel-based segmentation method which employs a multi-layer perceptron neural network to classify the gray-scale image into vegetation and nonvegetation pixels. The input data of the neural network for each pixel are 2-dimensional gray-level values surrounding the pixel. To generate a gray-scale image from a raw RGB color image, a well-known color index called Excess Green minus Excess Red Index was used. Experimental results using 80 field images of 4 vegetation species demonstrate the superiority of the neural network to existing threshold-based segmentation methods in terms of accuracy, precision, recall, and harmonic mean.

Analysis of Influential Factors from Rainfall to Stream Water Quality in Small Forested Watershed - pH, dissolved oxygen, electrical conductivity - (산림유역내(山林流域內) 강수(降水)로부터 계류수질(溪流水質)에 미치는 영향인자(影響因子) 분석(分析) - pH, 용존산소(溶存酸素), 전기전도도(電氣傳導度) -)

  • Park, Jae-Hyeon;Woo, Bo-Myeong
    • Journal of Korean Society of Forest Science
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    • v.86 no.4
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    • pp.489-501
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    • 1997
  • This research was conducted to analyze the influence of the environmental factors on water quality such as pH, dissolved oxygen, and electrical conductivity of rainfall, throughfall, soil water(A and B layer), and stream water quality at a small forested watershed. Rainfall, throughfall, soil water(A and B layer), and stream water were sampled at the study sites in Kwanak Arboretum, Seoul National University in Mt. Kwanak for 14 months(Jul. 1, 1996~Aug. 31, 1997). Average rainfall pH value was 6.06(ranged from 5.02 to 6.60). Acid rain frequency(less than pH 5.6) was 16.7%. The lowest rainfall pH value was 5.02. Average of pH values in hydrological processes were decreasing in the following order, stream water>soil water [Prunus serrulata var, spontanea(B layer>A layer)]>throughfall(Prunus serrulata var. spontanea)>soil water [Carpinus laxiflora(B layer >A layer)]>throughfall(Carpinus laxiflora)>rainfall>soil water [Pinus rigida(B layer>A layer)]>throughfall(Pinus rigida). pH values of throughfall in Prunes serrulata var. spontanea and Carpinus laxiflora were higher in Pines rigida. Average of dissolved oxygen values in hydrological processes were decreasing in the order, stream water>throughfall(Carpinus laxiflora>Prunus serrulata var, spontanea>Pines rigida)>rainfall>soil water [Prunes serrulata var. spontanea(A layer)>Pines rigida(A layer)>Carpinus laxiflora(A layer)>Prunes serrulata var. spontanea(B layer)>Pines rigida(B layer)>Carpinus laxiflora(B layer)]. And average electrical conductivity values in hydrological processes were decreasing in the order, soil water (B layer>A layer)>throughfall(Pinus rigida>Prunes serrulata var, spontanea>Carpinus laxiflora)>stream water>rainfall. Multiple regression equations of electrical conductivity and $Mg^{2+}$, $Na^+$, total amount of cation, total amount of ion, and no. of before non-rain days in rainfall, throughfall, soil and stream water shows high significance(Multi R; 0.84).

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Seismic Performance of Bridge with Pile Bent Structures in Soft Ground against Near-Fault Ground Motions (연약지반에 건설된 단일형 현장타설말뚝 교량의 근단층지반운동에 대한 내진성능)

  • Sun, Chang-Ho;An, Sung-Min;Kim, Jung-Han;Kim, Ick-Hyun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.7
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    • pp.137-144
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    • 2019
  • For the structures near the seismogenic fault, the evaluation of seismic performance against near-fault ground motions is important as well as for design ground motions. In this study, characteristics of seismic behaviors and seismic performance of the pile-bent bridge constructed on the thick soft soil site with various weak soil layers were analyzed. The input ground motions were synthesized by the directivity pulse parameters for intra-plate regions. The ground motion acceleration histories of each layer were obtained by one-dimensional site response analysis. Each soil layer was modeled by equivalent linear springs, and multi-support excitations with different input ground motions at each soil spring were applied for nonlinear seismic analyses. The analysis result by the near-fault ground motions and ground motions matched to design spectra were compared. In case of the near fault ground motion input, the bridge behaved within the elastic range but the location of the maximum moment occurred was different from the result of design ground motion input.

임기광산 폐석적치장의 수리침투특성 분석

  • 지상우;정영욱;임길재
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2004.09a
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    • pp.394-398
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    • 2004
  • This study was carried out to plan the prevention of the generation and discharge of acid mine drainage (AMD). Hydraulic characteristics were tested with the disk tension infiltrometer around the waste rock dump of the Imgi abandoned pyrophyllite mine in Busan, Korea. Because the waste rock dump of the Imgi mine have very low infiltration rate, most of rain was expected flowing into adjoined stream through the slope or plane as surface flow rather then throughflow or ground water. But slopes of the waste rock dump have many 'V' type erosion gullies and consist multi-layers. These gullies and multi-layers have coarse clastic particle layer which have very large hydraulic conductivity. So through these coarse clastic particle layers a large part of rain flow into ground. And also these layers could be played a function of aeration path, which induced oxidation of sulfide minerals and generation of AMD continuously.tinuously.

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Back Analysis of the Earth Wall in Multi-layered Subgrade (다층지반에 근입된 흙막이 벽의 역해석에 관한 연구)

  • 이승훈;김종민;김수일;장범수
    • Journal of the Korean Geotechnical Society
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    • v.18 no.1
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    • pp.71-78
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    • 2002
  • This paper presents a back-calculation technique leer the prediction of the behavior of earth wall inserted in multi-layered soil deposit. The soil properties are back-calculated from the measured displacement at each construction stage and the behavior of earth wall far the next construction stage is predicted using back-calculated soil properties. For multi-layered soil deposit, the back-calculation would be very difficult due to the increase in the number of variables. In this study, to solve this difficulty, the back-calculation was performed successively from the lowest layer to the upper layers. An efficient elasto-plastic beam-column analysis was used for forward analysis to minimize the computation time of iterative back-calculation procedure. The coefficients of subgrade reaction and lateral earth pressure necessary for the formation of p-y curve were selected as back calculation variables, and to minimize the effect of abnormal behavior of the wall which might be caused by any unexpected action during construction, the difference between measured displacement increment and computed displacement increment at each construction stages is used as the objective function of optimization. The constrained sequential linear programming was used for the optimization technique to found values of variables minimizing the objective function. The proposed method in this study was verified using numerically generated data and measured field data.

Planting foundations and Turfgrass Species Adapted to Grounds (스포츠 그라운드에 적합한 식재지반과 잔디 초종에 관한 연구)

  • 심상렬;정대영;김경남
    • Journal of the Korean Institute of Landscape Architecture
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    • v.28 no.2
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    • pp.61-70
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    • 2000
  • The purpose of this study is to identify the proper species of turf and the ground structure for the turf sports grounds. Analysis items are particle distribution of sand and gravel, saturated hydraulic conductivity, soil hardness, and turf growth. Results of this study are as follows. 1)The particle distribution of sand used in the multi-layer rootzone is within the upper limit of the standard level. The diameter of mid-size grain({TEX}$D_{50}${/TEX})was 0.62mm and the value of uniformity ({TEX}$D_{90}${/TEX}/{TEX}$D_{10}${/TEX}) was 3.93. The particle size distribution of sand used in the single-layer rootzone was beyond the standard level as {TEX}$D_{50}${/TEX})=0.86 and {TEX}$D_{90}${/TEX}/{TEX}$D_{10}${/TEX}=8.86. 2) Saturated hydraulic conductivity of the sand was higher in the multi-layer rootzone than in the single-layer rootzone while bulk density was vice versa. 3) Surface hardness was high on Kentucky bluegrass+perennial ryegrass compared to zoysiagrass probably caused by root density. 4) Visual covering and visual rating were highly evaluated on zoysiagrass within summer while better evaluated on Kentucky bluegrass+perennial ryegrass throughout fall to spring. 5) Visual color was better evaluated on Kentucky bluegrass+perennial ryegrass than on zoysiagrass throughout the year. These studies are demanded urgently according to increase in interest in the ground and turf species of the turf sports ground because of World Cup 2002.

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Behavior of Pile Groups in Multi-layers Soil under Lateral Loading (다층지반에서 횡하중을 받는 군말뚝의 거동)

  • Kim, Yongmoon;Ahn, Kwangkuk
    • Journal of the Korean GEO-environmental Society
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    • v.13 no.3
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    • pp.85-90
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    • 2012
  • This paper deals with the results for a numerical analysis of single piles and pile groups in multi-layers soil(granite soil-clay-granite soil) subjected to monotonous lateral loading using the ABAQUS finite element software. The investigated variables in this study include free head and embedded capped single pile, pile diameter (0.5m), pile length (10m), and pile groups. Numerical analyses were conducted by variation of spacing piles(s=3D, 4D, 5D) to compare the behaviour of single pile without cap and group pile. The $1{\times}3$ pile group(leading pile, middle pile, trail pile) was selected to investigate the individual pile and group lateral resistance, the distribution of the resistance among the piles. The analysis model of clay and the material of granite soil was modeled by using Druker-Prager constitutive relationship and existing treatise respectively. The pile was considered as a elastic circular concrete pile. As a result, the more pile space was extended, the value of P-multiplier is appeared to be less effective to leading pile. The lateral resistance of single-layer showed approximately 4-20% larger than the multi-layers.

The Change of Soil Animals by Forest Ecosystem Restoration Types (산림생태계 복원유형별 토양동물 변화)

  • Kang, Hyun-Mi;Song, Jae-Tak;Choi, Song-Hyun;Kim, Dong-Hyo
    • Korean Journal of Environment and Ecology
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    • v.31 no.1
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    • pp.62-71
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    • 2017
  • In this study, in order to examine the change of soil animals by vegetation restoration types, experimental sites with biotope restoration method, forest topsoil paving method, small diameter trees planting method and multi-layer community planting method were applied and the control site was selected. The naturalness of soil animals was analysed by studying the change of soil animals. It was confirmed that the control site has a high level of the naturalness of soil animals as it includes a mixture of fauna sensitive and insensitive to environment distributed widely over the site. The experimental site with biotope restoration method showed a similar level of the naturalness of soil animals as the control site. Furthermore, the naturalness of soil animals in the experimental sites with small diameter trees planting method and multi-layer community planting method also showed a progressive restoration although the level of the naturalness of soil animals is lower than the experimental site with the biotope restoration method. Therefore, it is confirmed that the experimental site with biotope restoration method shows a faster recovery of soil animal than other sites. This is because this method uses the portion of topsoil and subsoil that were dug from the intact forest during transplantation.

5-SRICOS Method : Prediction of Scour Depth Around Bridge Piers in Cohesive Soils (S-SRICOS 방법 : 점성토지반의 교각세굴깊이 예측)

  • 곽기석
    • Journal of the Korean Geotechnical Society
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    • v.18 no.2
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    • pp.13-21
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    • 2002
  • A new method called S-SRICOS is proposed to predict the local scour depth around bridge piers. The S-SRICOS method is a simplified version of the SRICOS method which was developed to predict the scour depth versus time curve around bridge piers. The SRICOS method which considers the time effect based on the soil properties and the hydraulic parameters can handle a multi-flood hydrograph and multi-layer soil systems with the SRICOS program. An attempt was made to simplify the method to the point where only hand calculations would be required. The concept of the equivalent time was developed leer this purpose. The S-SROICOS method requires only 4 parameters such as pier width, design bridge life, design velocity corresponding to the design bridge life, and initial scour rate of the soil. The S-SRICOS method was verified against 55 cases of the scour depth results using the SRICOS method.