• Title/Summary/Keyword: probabilistic analysis

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The Analysis of the Seepage Quantity of Reservoir Embankment using Stochastic Response Surface Method (확률론적 응답면 기법을 이용한 저수지 제체의 침투수량 해석)

  • Bong, Tae-Ho;Son, Young-Hwan;Noh, Soo-Kack;Choi, Woo-Seok
    • Journal of The Korean Society of Agricultural Engineers
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    • v.55 no.3
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    • pp.75-84
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    • 2013
  • The seepage quantity analysis of reservoir embankment is very important for assessment of embankment safety. However, the conventional analysis does not consider uncertainty of soil properties. Permeability is known that the coefficient of variation is larger than other soil properties and seepage quantity is highly dependent on the permeability of embankment. Therefore, probabilistic analysis should be carried out for seepage analysis. To designers, however, the probabilistic analysis is not an easy task. In this paper, the method that can be performed probabilistic analysis easily and efficiently through the numerical analysis based commercial program is proposed. Stochastic response surface method is used for approximate the limit state function and when estimating the coefficients, the moving least squares method is applied in order to reduce local error. The probabilistic analysis is performed by LHC-MCS through the response surface. This method was applied to two type (homogeneous, core zone) earth dams and permeability of embankment body and core are considered as random variables. As a result, seepage quantity was predicted effectively by response surface and probabilistic analysis could be successfully implemented.

The probabilistic Analysis of Degree of Consolidation by Spatial Variability of Cv (압밀계수의 공간변동성에 따른 압밀도의 확률론적 해석)

  • Bong, Tae-Ho;Son, Young-Hwan;Noh, Soo-Kack;Park, Jae-Sung
    • Journal of The Korean Society of Agricultural Engineers
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    • v.54 no.3
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    • pp.55-63
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    • 2012
  • Soil properties are not random values which is represented by mean and standard deviation but show spatial correlation. Especially, soils are highly variable in their properties and rarely homogeneous. Thus, the accuracy and reliability of probabilistic analysis results is decreased when using only one random variable as design parameter. In this paper, to consider spatial variability of soil property, one-dimensional random fields of coefficient of consolidation ($C_v$) were generated based on a Karhunen-Loeve expansion. A Latin hypercube Monte Calro simulation coupled with finite difference method for Terzaghi's one dimensional consolidation theory was then used to probabilistic analysis. The results show that the failure probability is smaller when consider spatial variability of $C_v$ than not considered and the failure probability increased when the autocorrelation distance increased. Thus, the uncertainty of soil can be overestimated when spatial variability of soil property is not considered, and therefore, to perform a more accurate probabilistic analysis, spatial variability of soil property needed to be considered.

Minimum Expected Cost based Design of Vertical Drain Systems (최소기대비용에 의한 연직배수시설의 설계)

  • Kim, Seong-Pil;Son, Young-Hwan;Chang, Pyung-Wook
    • Journal of The Korean Society of Agricultural Engineers
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    • v.49 no.6
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    • pp.93-101
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    • 2007
  • In general, geotechnical properties have many uncertain aspects, thus probabilistic analysis have been used to consider these aspects. It is, however, quite difficult to select an appropriate target probability for a certain structure or construction process. In this study, minimum expected cost design method based on probabilistic analysis is suggested for design of vertical drains generally used to accelerate consolidation in soft clayey soils. A sensitivity analysis is performed to select the most important uncertain parameters for the design of vertical drains. Monte Carlo simulation is used in sensitivity analysis and probabilistic analysis. Total expected cost, defined as the sum of initial cost and expected additive cost, varies widely with variation of input parameters used in design of vertical drain systems. And probability of failure to get the minimum total expected cost varies under the different design conditions. A minimum value of total expected cost is suggested as a design value in this study. The proposed design concept is applicable to unit construction process because this approach is to consider the uncertainties using probabilistic analysis and uncertainties of geotechnical properties.

Probabilistic Analysis of Vertical Drains using Hasofer-Lind Reliability Index (신뢰성지수를 이용한 연직배수공법의 확률론적 해석)

  • Kim, Seong-Pil;Heo, Joon;Bong, Tae-Ho
    • Journal of The Korean Society of Agricultural Engineers
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    • v.53 no.6
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    • pp.1-6
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    • 2011
  • The conventional factor of safety as used in geotechnical engineering does not reflect the degree of uncertainty of the relevant parameters. Then in the geotechnical engineering, there have been efforts to reflect the uncertainties of the geotechnical properties through probabilistic analysis. In this study, a practical method for probabilistic analysis using the Hasofer-Lind reliability index is introduced. The method is based on the perspective of an ellipsoid that just touches the failure surface in the original space of the variables. The method is applied to prefabricated vertical drains (PVD) and compared with the result of Monte Carlo Simulation method.

Development of a New Method to Consider Uncertainty of 1-D Soil Profile for the Probabilistic Analysis (확률론적 지반 해석을 위한 1차원 지반 구조의 불확실성 고려 방법의 개발)

  • Hwang, Hea-Jin;Park, Hyung-Choon
    • Journal of the Korean Geotechnical Society
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    • v.29 no.3
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    • pp.41-50
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    • 2013
  • There always exists uncertainty which is mainly due to uncertainty of the evaluation of a geotechnical structure at a site. The uncertainty in the geotechnical analysis can be considered in the probabilistic analysis using the Monte Carlo Simulation. It needs various soil profiles which could be possible at the target site. In this study, a new method is proposed to generate soil profiles which are probable at the site. The proposed method analyzes a structure of a site and generates one dimensional soil profiles for a probabilistic analysis. Through the field application, the applicability of the prosed method was shown.

Dynamic Analysis of Suspension for Small Form Factor MO Drive (초소형 광자기 드라이브용 서스펜션의 동특성 해석)

  • 홍어진;오우석;박노철;양현석;박영필
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.406-411
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    • 2003
  • One of the trends on information storage device is focused on the development of micro-optical devices with OFH (Optical Flying Head). Many different types of sliders for OFH and optical component systems have been introduced in the literature. However, the important issue on the mechanical system, which consists of suspension, swing arm and VCM (Voice Coil Motor) part has not been discussed up to date. In this research, we analyses the suspension, which is used for the small form factor MO drive. The analysis is in process two ways. One is probabilistic analysis, another is dynamic shock analysis. Probabilistic analysis is a technique you can use to assess the effect of uncertain input parameters and assumptions on your analysis model. Using a probabilistic analysis you can and out how much the results of a finite elements analysis are affected by uncertainties in the model. Dynamic shock analysis is used for the mobile applications. The mechanical robustness of the suspension simulating the shock responses of a disk-suspension is proposed in this paper.

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Probabilistic Analysis of Dynamic Characteristics of Structures considering Joint Fastening and Tolerance (체결부 및 공차를 고려한 구조물의 확률기반 동적 특성 연구)

  • Won, Jun-Ho;Kwang, Kang-Jin;Choi, Joo-Ho
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.18 no.4
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    • pp.44-50
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    • 2010
  • Structural vibration is a significant problem in many multi-part or multi-component assemblies. In aircraft industry, structures are composed of various fasteners, such as bolts, snap, hinge, weld or other fastener or connector (collectively "fasteners"). Due to these, prediction and design involving dynamic characteristics is quite complicated. However, the current state of the art does not provide an analytical tool to effectively predict structure's dynamic characteristics, because consideration of structural uncertainties (i.e. material properties, geometric tolerance, dimensional tolerance, environment and so on) is difficult and very small fasteners in the structure cause a huge amount of analysis time to predict dynamic characteristics using the FEM (finite element method). In this study, to resolve the current state of the art, a new approach is proposed using the FEM and probabilistic analysis. Firstly, equivalent elements are developed using simple element (e.g. bar, beam, mass) to replace fasteners' finite element model. Developed equivalent elements enable to explain static behavior and dynamic behavior of the structure. Secondly, probabilistic analysis is applied to evaluate the PDF (probability density function) of dynamic characteristics due to tolerance, material properties and so on. MCS (Monte-Carlo simulation) is employed for this. Proposed methodology offers efficiency of dynamic analysis and reality of the field as well. Simple plates joined by fasteners are taken as an example to illustrate the proposed method.

Probabilistic analysis of peak response to nonstationary seismic excitations

  • Wang, S.S.;Hong, H.P.
    • Structural Engineering and Mechanics
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    • v.20 no.5
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    • pp.527-542
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    • 2005
  • The main objective of this study is to examine the accuracy of the complete quadratic combination (CQC) rule with the modal responses defined by the ordinates of the uniform hazard spectra (UHS) to evaluate the peak responses of the multi-degree-of-freedom (MDOF) systems subjected to nonstationary seismic excitations. For the probabilistic analysis of the peak responses, it is considered that the seismic excitations can be modeled using evolutionary power spectra density functions with uncertain model parameters. More specifically, a seismological model and the Kanai-Tajimi model with the boxcar or the exponential modulating functions were used to define the evolutionary power spectral density functions in this study. A set of UHS was obtained based on the probabilistic analysis of transient responses of single-degree-of-freedom systems subjected to the seismic excitations. The results of probabilistic analysis of the peak responses of MDOF systems were obtained, and compared with the peak responses calculated by using the CQC rule with the modal responses given by the UHS. The comparison seemed to indicate that the use of the CQC rule with the commonly employed correlation coefficient and the peak modal responses from the UHS could lead to significant under- or over-estimation when contributions from each of the modes are similarly significant.

Probabilistic Approach of Stability Analysis for Rock Wedge Failure (확률론적 해석방법을 이용한 쐐기파괴의 안정성 해석)

  • Park, Hyuck-Jin
    • Economic and Environmental Geology
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    • v.33 no.4
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    • pp.295-307
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    • 2000
  • Probabilistic analysis is a powerful method to quantify variability and uncertainty common in engineering geology fields. In rock slope engineering, the uncertainty and variation may be in the form of scatter in orientations and geometries of discontinuities, and also test results. However, in the deterministic analysis, the factor of safety which is used to ensure stability of rock slopes, is based on the fixed representative values for each parameter without a consideration of the scattering in data. For comparison, in the probabilistic analysis, these discontinuity parameters are considered as random variables, and therefore, the reliability and probability theories are utilized to evaluate the possibility of slope failure. Therefore, in the probabilistic analysis, the factor of safety is considered as a random variable and replaced by the probability of failure to measure the level of slope stability. In this study, the stochastic properties of discontinuity parameters are evaluated and the stability of rock slope is analyzed based on the random properties of discontinuity parameters. Then, the results between the deterministic analysis and the probabilistic analysis are compared and the differences between the two analysis methods are explained.

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Probabilistic Analysis of Vertical Drains Using Spreadsheet (Spreadsheet를 이용한 연직배수공법의 확률론적 해석)

  • Kim, Seong-Pil;Heo, Joon;Yoon, Chang-Jin
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.09a
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    • pp.1024-1029
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    • 2010
  • The conventional factor of safety as used in geotechnical engineering does not reflect the degree of uncertainty of the relevant parameters. Then in the geotechnical engineering, there have been efforts to reflect the uncertainties of the geotechnical properties through probabilistic analysis. In this study, a practical method for calculation the second moment reliability index using the optimization tool of a spreadsheet software is introduced. And this methodology was proposed by Low, B. K.(1996). The method is based on the perspective of an ellipsoid that just touches the failure surface in the original space of the variables. The method is applied to vertical drains(PVD) and compared with th result of Monte Carlo Simulation method.

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