• Title/Summary/Keyword: Kriging method

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A Robust Design Using Approximation Model and Probability of Success (근사모델 및 성공확률을 이용한 강건설계)

  • Song, Byoung-Cheol;Lee, Kwon-Hee
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.7 no.3
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    • pp.3-11
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    • 2008
  • Robust design pioneered by Dr. G. Taguchi has been applied to versatile engineering problems for improving quality. Since 1980s, the Taguchi method has been introduced to numerical optimization, complementing the deficiencies of deterministic optimization, which is often called the robust optimization. In this study, the robust optimization strategy is proposed by considering the robustness of objective and constraint functions. The statistics of responses in the functions are surrogated by kriging models. In addition, objective and/or constraint function is represented by the probability of success, thus facilitating robust optimization. The mathematical problem and the two-bar design problem are investigated to show the validity of the proposed method.

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A PRACTICAL THREE-DIMENSIONAL ESTIMATION TECHNIQUE FOR SPATIAL DISTRIBUTION OF GROUNDWATER CONTAMINANT CONCENTRATIONS

  • Richard Ewing;Kang, Sung-Kwon;Kim, Jeon-Gook;Thomas B.Stauffer
    • Journal of the Korean Mathematical Society
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    • v.38 no.3
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    • pp.523-559
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    • 2001
  • To predict the fate of groundwater contaminants, accurate spatially continuous information is needed. Because most field sampling of groundwater contaminants are not conducted spatially continuous manner, a special estimation technique is required to interpolate/extrapolate concentration distributions at unmeasured locations. A practical three-dimensional estimations method for in situ groundwater contaminant concentrations is introduced. It consistas of two general steps: estimation of macroscopic transport process and kriging. Using field data and nonlinear optimization techniques, the macroscopic behavior of the contaminant plume is estimated. A spatial distribution of residuals is obtained by subtracting the macroscopic transport portion from field data, then kriging is applied to estimate residuals at unsampled locations. To reduce outlier effects on obtaining correlations between residual data which are needed for determining variougram models, the R(sub)p-estimator is introduced. The proposed estimation method is applied to a field data set.

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Shape Optimization of a Segment Ball Valve Using Metamodels

  • Lee, Jin-Hwan;Lee, Kwon-Hee
    • Journal of Navigation and Port Research
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    • v.34 no.7
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    • pp.553-558
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    • 2010
  • This study presents the optimization design process of a segment ball valve that involves the reduction of the flow resistance coefficient and the satisfaction of the strength requirement. Numerical analysis of fluid flow and structural analysis have been performed to predict the flow resistance coefficient and the maximum stress of a segment ball valve. In this study, a segment ball valve incorporating the advantages of a ball valve and a butterfly valve has been devised. In general, ball valves are installed in a pipe system where tight shut off is required. Butterfly valves having smaller end-to-end dimension than ball valve can be installed in narrow spaces in a pipe system. The metamodels for the shape design of a segment ball valve are built by the response surface method and the Kriging interpolation model.

Method for Evaluating Optimal Air Monitoring Sites for SO2 in Ulsan (울산광역시 아황산가스(SO2)의 최적관측소 평가방법)

  • Lim, Junghyun;Yoon, Sanghoo
    • Journal of Environmental Science International
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    • v.26 no.9
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    • pp.1073-1080
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    • 2017
  • Manufacturing and technology industries produce large amounts of air pollutants. Ulsan Metropolitan City, South Korea, is well-known for its large industrial complexes; in particular, the concentration of $SO_2$ here is the highest in the country. We assessed $SO_2$ monitoring sites based on conditional and joint entropy, because this is a common method for determining an optimal air monitoring network. Monthly $SO_2$ concentrations from 12 air monitoring sites were collected, and the distribution of spatial locations was determined by kriging. Mean absolute error, Root Mean Squared Error (RMSE), bias and correlation coefficients were employed to evaluate the considered algorithms. An optimal air monitoring network for Ulsan was suggested based on the improvement of RMSE.

Sequential Feasible Domain Sampling of Kriging Metamodel by Using Penalty Function (벌칙함수 기반 크리깅메타모델의 순차적 유용영역 실험계획)

  • Lee Tae-Hee;Seong Jun-Yeob;Jung Jae-Jun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.6 s.249
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    • pp.691-697
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    • 2006
  • Metamodel, model of model, has been widely used to improve an efficiency of optimization process in engineering fields. However, global metamodels of constraints in a constrained optimization problem are required good accuracy around neighborhood of optimum point. To satisfy this requirement, more sampling points must be located around the boundary and inside of feasible region. Therefore, a new sampling strategy that is capable of identifying feasible domain should be applied to select sampling points for metamodels of constraints. In this research, we suggeste sequential feasible domain sampling that can locate sampling points likely within feasible domain by using penalty function method. To validate the excellence of feasible domain sampling, we compare the optimum results from the proposed method with those form conventional global space-filling sampling for a variety of optimization problems. The advantages of the feasible domain sampling are discussed further.

Shape Design of an Outer Tie Rod, Considering Durability Criteria (내구 기준을 고려한 아우터 타이 로드의 형상 설계)

  • Kim, Jong-Kyu;Kwon, Young-Min;Park, Young-Chul;Lee, Kwon-Hee
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.8 no.4
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    • pp.54-60
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    • 2009
  • Weight reduction of automobile parts has been sought to achieve fuel efficiency and energy conservation. In this study, a shape design procedure is suggested to obtained the lightweight design of an outer tie rod. The developed aluminium Al6082M is selected as a steel-substitute material. Strength assesment and durability are the important design criterion in the structural design of an outer tie rod. This study considers strength and durability in the optimization process. In this study, the kriging interpolation method and trial and error method are adopted to obtain the minimum weight satisfying the strength and durability constraints.

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Structural Optimization of a Manifold Valve for Pressure Vessel (압력용기 매니폴드 밸브의 구조최적설계)

  • Bae, Tae-Sung;Kim, Si-Pom;Lee, Kwon-Hee
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.12
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    • pp.102-109
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    • 2009
  • This study proposes the structural optimization of a manifold valve. FE analysis is performed to evaluate the strength of a manifold valve. In addition, the structural optimization technique is applied to reduce its weight. In this study, the optimization method using the kriging interpolation method is adopted to obtain the minimum weight satisfying the strength constraint. The maximum stress and the weight are replaced by the metamodels. In this process, tile sample points are generated by latin-hypercube design. Optimum designs are obtained by ANSYS Workbench and the in-house program.

A Study on Spatial Characteristics of Rainfall in Imha Basin (임하 유역 강우의 공간적 특성에 관한 연구)

  • Lee, Sang-Jin;Lee, Bae-Sung;Kang, Bu-Sick;Hwang, Man-Ha
    • Journal of The Korean Society of Agricultural Engineers
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    • v.49 no.1
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    • pp.3-13
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    • 2007
  • In this study, spatial characteristics of rainfall in Imha basin were investigated by cross-correlation analysis among rainfall gaging stations and rainfall-runoff analysis used in HEC-HMS model for analysis of influence on observed rainfall. The Kriging technique was applied to rain(all analysis in Imha basin to reflect spatial characteristics of regional rainfall. Their results are compared to rainfall-runoff data with spatially distributed rainfall data as well as the classical thiessen method. The results by kriging technique approached by geostatistical method could reflect spatial characteristics of regional rainfall properly in Imha basin.

Louvered Fin Heat Exchanger : Optimal Design and Numerical Investigation of Heat and Flow Characteristics (루버휜 최적 설계 및 최적 모델의 열유동 특성 분석)

  • Ryu, Kijung;Lee, Kwan-Soo
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.25 no.12
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    • pp.654-659
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    • 2013
  • This paper presents a numerical optimization of louvered fins to enhance the JF factor in terms of the design parameters, including the fin pitch, the number of louvers, the louver angle, the fin thickness, and the re-direction louver length. We carried out a parametric study to select the three most important parameters affecting the JF factor, which were the fin pitch, number of louvers, and the louver angle. We optimally designed the louvered fin by using 3rd-order full factorial design, the kriging method, and a micro genetic algorithm. Consequently, the JF factor of the optimum model increased by 16% compared to that of the base model. Moreover, the optimum model reduced the pressure drop by 17% with a comparable heat transfer rate.

Conceptual Design Optimization of Tensairity Girder Using Variable Complexity Modeling Method

  • Yin, Shi;Zhu, Ming;Liang, Haoquan;Zhao, Da
    • International Journal of Aeronautical and Space Sciences
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    • v.17 no.1
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    • pp.29-36
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    • 2016
  • Tensairity girder is a light weight inflatable fabric structural concept which can be used in road emergency transportation. It uses low pressure air to stabilize compression elements against buckling. With the purpose of obtaining the comprehensive target of minimum deflection and weight under ultimate load, the cross-section and the inner pressure of tensairity girder was optimized in this paper. The Variable Complexity Modeling (VCM) method was used in this paper combining the Kriging approximate method with the Finite Element Analysis (FEA) method, which was implemented by ABAQUS. In the Kriging method, the sample points of the surrogate model were outlined by Design of Experiment (DOE) technique based on Optimal Latin Hypercube. The optimization framework was constructed in iSIGHT with a global optimization method, Multi-Island Genetic Algorithm (MIGA), followed by a local optimization method, Sequential Quadratic Program (SQP). The result of the optimization gives a prominent conceptual design of the tensairity girder, which approves the solution architecture of VCM is feasible and efficient. Furthermore, a useful trend of sensitivity between optimization variables and responses was performed to guide future design. It was proved that the inner pressure is the key parameter to balance the maximum Von Mises stress and deflection on tensairity girder, and the parameters of cross section impact the mass of tensairity girder obviously.