• Title/Summary/Keyword: initial slope

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Shallow Landslide Assessment Considering the Influence of Vegetation Cover

  • Viet, Tran The;Lee, Giha;Kim, Minseok
    • Journal of the Korean GEO-environmental Society
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    • v.17 no.4
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    • pp.17-31
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    • 2016
  • Many researchers have evaluated the influence of vegetation cover on slope stability. However, due to the extensive variety of site conditions and vegetation types, different studies have often provided inconsistent results, especially when evaluating in different regions. Therefore, additional studies need to be conducted to identify the positive impacts of vegetation cover for slope stabilization. This study used the Transient Rainfall Infiltration and Grid-based Regional Slope-stability Model (TRIGRS) to predict the occurrence of landslides in a watershed in Jinbu-Myeon, Pyeongchang-gun, Korea. The influence of vegetation cover was assessed by spatially and temporally comparing the predicted landslides corresponding to multiple trials of cohesion values (which include the role of root cohesion) and real observed landslide scars to back-calculate the contribution of vegetation cover to slope stabilization. The lower bound of cohesion was defined based on the fact that there are no unstable cells in the raster stability map at initial conditions, and the modified success rate was used to evaluate the model performance. In the next step, the most reliable value representing the contribution of vegetation cover in the study area was applied for landslide assessment. The analyzed results showed that the role of vegetation cover could be replaced by increasing the soil cohesion by 3.8 kPa. Without considering the influence of vegetation cover, a large area of the studied watershed is unconditionally unstable in the initial condition. However, when tree root cohesion is taken into account, the model produces more realistic results with about 76.7% of observed unstable cells and 78.6% of observed stable cells being well predicted.

Texture of Chewing Gum: Instrumental and Sensory Rheological Characteristics (츄잉검의 텍스쳐 : 기계적(機械的) 물성(物性)과 관능적(官能的) 특성(特性))

  • Pyun, Yu-Ryang;Yoo, Myung-Shik;Lee, Yoon-Hyung
    • Korean Journal of Food Science and Technology
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    • v.16 no.3
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    • pp.303-308
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    • 1984
  • Instrumental and sensory characteristics of chewing gums were measured at each masticatory stage, and the correlations between the characteristics were analyzed. In instrumental characteristics, similarities were proved between initial puncture work and puncture force, intermediate hardness and penetration work, final hardness and penetration work, and adhesion work and adhesion force. Final hardness correlated highly with yield force and the slope of force-distance curve of penetration test, and the slope also correlated significantly with springiness and adhesion force. In sensory characteristics, the correlations of the same parameter between trained panel and consumer were extremely high. Initial stiffness correlated significantly with both intermediate and final firmness by consumer. Highly significant correlations were obtained between final firmness and stiffness and between lift and cohesion by trained panel, whereas firmness correlated with adhesion negatively.

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Initial Mass Functions of Massive Stars in OB Associations

  • Kang, Yong-Hee
    • Publications of The Korean Astronomical Society
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    • v.2 no.1
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    • pp.30-38
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    • 1985
  • We derived initial mass functions (IMF) of massive stars in three different regions of spiral arms within 2.5kpc from the sun. The derived IMF slope $\beta$ of Local arm stars is found to be $-2.09{\sim}-2.06$, very close to that of Bisiacchi et al. (1983). For Sagittarius-Carina arm stars $\beta$ ranges from -1.77 to - 1.72 which is close to that of overall stars given by Germany et al. (1982). Possible causes inducing the regional difference in IMFs are discussed.

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Velocity Estimation of a Compass Gait Biped Robot by Using Impact Condition and Initial Condition Reset (충돌 조건과 초기치 리셋을 이용한 컴퍼스 이족 로봇의 속도 추정)

  • Son, Young-Ik
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.11
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    • pp.2266-2268
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    • 2009
  • In this paper, a simple method of angle velocity estimation is presented for a passive dynamic biped robot. The estimation problem is not an easy task because its dynamic model is a hybrid system involved with an impact condition. Instead of designing a complex observer for hybrid systems we simply utilize the impact condition to reset the initial condition of the high-pass filter when the non-support leg hits the slope. The approach has been verified by simulation results.

NUMERICAL SIMULATION OF TWO-DIMENSIONAL FREE-SURFACE FLOW AND WAVE TRANSFORMATION OVER CONSTANT-SLOPE BOTTOM TOPOGRAPHY

  • DIMAKOPOULOS AGGELOS S;DIMAS ATHANASSIOS A
    • Proceedings of the Korea Water Resources Association Conference
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    • 2005.09b
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    • pp.842-845
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    • 2005
  • A method for the numerical simulation of two-dimensional free-surface flow resulting from the propagation of regular gravity waves over topography with arbitrary bottom shape is presented. The method is based on the numerical solution of the Euler equations subject to the fully nonlinear free-surface boundary conditions and the appropriate bottom, inflow and outflow conditions using a hybrid finite-differences and spectral-method scheme. The formulation includes a boundary-fitted transformation, and is suitable for extension to incorporate large-eddy simulation (LES) and large-wave simulation (LWS) terms for turbulence and breaking wave modeling, respectively. Results are presented for the simulation of the free-surface flow over two different bottom topographies, with constant slope values of 1:10 and 1:20, two different inflow wave lengths and two different inflow wave heights. An absorption outflow zone is utilized and the results indicate minimum wave reflection from the outflow boundary. Over the bottom slope, lengths of waves in the linear regime are modified according to linear theory dispersion, while wave heights remain more or less unchanged. For waves in the nonlinear regime, wave lengths are becoming shorter, while the free surface elevation deviates from its initial sinusoidal shape.

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Effects of the Initial Texture on Formability in Aluminum Sheet Stretching (알루미늄 판재 스트래칭에서 초기 집합조직이 성형성에 미치는 영향)

  • Sim K. S.;Kim Y. I.;Lee Y. S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2001.10a
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    • pp.62-65
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    • 2001
  • The effects of the initial torture of workpiece as well as the process conditions such as punch speed and lubrication on the formablity of sheet stretching are investigated by experiments. Two types of the initial textures of aluminum sheet plane strain compression torture and recrystallization texture are chosen since those are the most common in practice. Punch loads vs depth and thickness strain distributions along radial directions having the slope of $0^{\circ},\;45^{\circ},\;90^{\circ}$ with rolling directions are reported for hemishperical punch stretchings under a variety of process conditions.

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Effect of Hydraulic Conductivity on Suction Profile and Stability of Cut-Slope during Low Intensity Rainfall (저강도 강우시 절토사면의 흡인력 분포와 안정성에 대한 투수계수의 효과)

  • Khalid, Mahmood;Kim, Jin-Man
    • Journal of the Korean Geotechnical Society
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    • v.28 no.6
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    • pp.63-70
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    • 2012
  • The authors discuss the effect of hydraulic conductivity on the suction profile and stability of a typical cut-slope subjected to low intensity rainfall. The initial suction value above the ground table in the unsaturated zone is assumed to be 15 kPa. The uncoupled approach of finite element and limit equilibrium method is used to evaluate the stability of the cut-slope at different elapsed times of rainfall. The finite element seepage analysis shows that the soil in the unsaturated zone always remains unsaturated during the course of low intensity rainfall. Furthermore, the slope stability remains practically unchanged so long as the wetting front remains in the unsaturated zone but it decreases noticeably when the wetting front reaches and elevates the ground water table level.

A new model approach to predict the unloading rock slope displacement behavior based on monitoring data

  • Jiang, Ting;Shen, Zhenzhong;Yang, Meng;Xu, Liqun;Gan, Lei;Cui, Xinbo
    • Structural Engineering and Mechanics
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    • v.67 no.2
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    • pp.105-113
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    • 2018
  • To improve the prediction accuracy of the strong-unloading rock slope performance and obtain the range of variation in the slope displacement, a new displacement time-series prediction model is proposed, called the fuzzy information granulation (FIG)-genetic algorithm (GA)-back propagation neural network (BPNN) model. Initially, a displacement time series is selected as the training samples of the prediction model on the basis of an analysis of the causes of the change in the slope behavior. Then, FIG is executed to partition the series and obtain the characteristic parameters of every partition. Furthermore, the later characteristic parameters are predicted by inputting the earlier characteristic parameters into the GA-BPNN model, where a GA is used to optimize the initial weights and thresholds of the BPNN; in the process, the numbers of input layer nodes, hidden layer nodes, and output layer nodes are determined by a trial method. Finally, the prediction model is evaluated by comparing the measured and predicted values. The model is applied to predict the displacement time series of a strong-unloading rock slope in a hydropower station. The engineering case shows that the FIG-GA-BPNN model can obtain more accurate predicted results and has high engineering application value.

Slope Stability Evaluation System of Sanitary Landfill on Soft Ground and Its Reliability (연약지반상 위생매립지 안정성 평가에 대한 문제점 분석과 개선방향)

  • 우동찬;송좌빈
    • Proceedings of the Korean Geotechical Society Conference
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    • 1997.03a
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    • pp.161-168
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    • 1997
  • The purpose of this study is to evaluate the possibility of normalization of the distibutions of soil parameters taken from soft ground and the reliability of the safety factors of specific objects on it, including sanitary landfill. Through this study it is found that distributions of soil parameters could be adjusted to appropriate normal distributions as possibility density functions(PDF), and that especially the group of initial cohesions and the coresponding safety factors has a perfect linear correlation. According to those results the PDF to initial cohesion as possibility parameter can not only be tmsformed to the PDF to safety factor but also, conseqently, the reliability of the safety factor(SF) simply based on the mean value of soil parameter(Co) can be calculated or easily picked up from the standrad normal distribution table. It is therefore concluded that even though calculated values of safety factors are over any standard requirements some possibility of risk both to the objects and natural soft ground could be still existing, and also a new standard value for this slope stability control system should be derived just by adjusting old one according to the magnitude of risk possibility.

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Evaluation of the q-w Curve on Rock-Socketed Drilled Shafts by Triaxial Compression Tests (삼축압축시험을 통한 암반에 근입된 현장타설말뚝의 선단 하중전이곡선 산정)

  • Kim, Tae-Hyung;Kim, Yong-Min;Jeong, Sang-Seom
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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    • pp.455-465
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    • 2008
  • In this study, the load distribution and deformation of rock-socketed drilled shafts subjected to axial load are investigated based on small scale model tests. In order to analyze the effects of major influencing factors of end bearing capacity, Hoek-cell triaxial tests were performed. From the test results, it was found that the initial slope of end bearing load transfer (q-w) curve was highly dependent on rock mass modulus and pile diameter, while the ultimate unit toe resistance ($q_{max}$) was influenced by rock mass modulus and the spacing of discontinuities. End bearing load transfer function of drilled shafts socketed in rock was proposed based on the Hoek-cell triaxial test results and the field loading tests which were performed on granite and gneiss in South Korea. Through the comparison with pile load tests, it is found that the load-transfer curve by the present study is in good agreement with the general trend observed by field loading tests, and thus represents a significant improvement in the prediction of load transfer of drilled shaft.

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