• Title/Summary/Keyword: kriging metamodel

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A NOVEL METHOD FOR REFINING A META-MODEL BY PARETO FRONTIER (파레토 프론티어를 이용한 메타모델 정예화 기법 개발)

  • Jo, S.J.;Chae, S.H.;Yee, K.J.
    • Journal of computational fluids engineering
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    • v.14 no.4
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    • pp.31-40
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    • 2009
  • Although optimization by sequentially refining metamodels is known to be computationally very efficient, the metamodel that can be used for this purpose is limited to Kriging method due to the difficulties related with sample points selections. The present study suggests a novel method for sequentially refining metamodels using Pareto Frontiers, which can be used independent of the type of metamodels. It is shown from the examples that the present method yields more accurate metamodels compared with full-factorial optimization and also guarantees global optimum irrespective of the initial conditions. Finally, in order to prove the generality of the present method, it is applied to a 2D transonic airfoil optimization problem, and the successful design results are obtained.

ROBUST DESIGN OPTIMIZATION OF RAE2822 AIRFOIL UNDER OPERATIONAL UNCERTAINTY USING METAMODEL (근사모델을 이용한 RAE2822 운용 불확실성 강건최적설계)

  • Bae, H.G.;Kwon, J.H.
    • 한국전산유체공학회:학술대회논문집
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    • 2010.05a
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    • pp.60-66
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    • 2010
  • In the view of robust design optimization, RAE2822 airfoil was designed to achieve not only the maximum lift-to-drag ratio but also insensitivity of that. While the RAE2822 is flying at the cruise speed, Mach variation is considered as the operational uncertainty. In order to explore the design space, metamodels were introduced instead of consecutively computing the gradient. Also a metamodel was used to represent the sigma space. Using the metamodel, an optimum value was searched in the view of global optimization.

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Aerodynamic Shape Design Method for Wing Planform Using Metamodel (근사모델을 이용한 날개 평면형상 공력형상설계 방법)

  • Bae, Hyogil;Jeong, Sora
    • Journal of Aerospace System Engineering
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    • v.8 no.4
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    • pp.18-23
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    • 2014
  • In preliminary design phase, the wing geometry of the civil aircraft was determined using the empirical equation and historical data. To make wing geometry more aerodynamically efficient, an aerodynamic shape optimization was conducted. For this purpose the parametric modeling, high fidelity CFD analysis and metamodel-based optimal design technique were adopted. The parametric modeling got the design process to achieve the improvement by generating the configuration outputs easily for the major design variables. The optimal design equations were formularized as the type of the multi-objective functions considering low/high speed and lift/drag coefficient. The optimal solution was explored with the help of the kriging metamodel and the desirability function, therefore the optimal wing planform was sought to be excellent at both low and high speed region. Additionally the optimal wing planform was validated that it was excellent not only at the specific AOA, but also all over the range of AOA.

Sensitivity Approach of Sequential Sampling for Kriging Model (민감도법을 이용한 크리깅모델의 순차적 실험계획)

  • Lee, Tae-Hee;Jung, Jae-Jun;Hwang, In-Kyo;Lee, Chang-Seob
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.11
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    • pp.1760-1767
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    • 2004
  • Sequential sampling approaches of a metamodel that sampling points are updated sequentially become a significant consideration in metamodeling technique. Sequential sampling design is more effective than classical space filling design of all-at-once sampling because sequential sampling design is to add new sampling points by means of distance between sampling points or precdiction error obtained from metamodel. However, though the extremum points can strongly reflect the behaviors of responses, the existing sequential sampling designs are inefficient to approximate extremum points of original model. In this research, new sequential sampling approach using the sensitivity of Kriging model is proposed, so that new approach reflects the behaviors of response sequentially. Various sequential sampling designs are reviewed and the performances of the proposed approach are compared with those of existing sequential sampling approaches by using mean squared error. The accuracy of the proposed approach is investigated against optimization results of test problems so that superiority of the sensitivity approach is verified.

Multiobjective optimization strategy based on kriging metamodel and its application to design of axial piston pumps (크리깅 메타모델에 기반한 다목적최적설계 전략과 액셜 피스톤 펌프 설계에의 응용)

  • Jeong, Jong Hyun;Baek, Seok Heum;Suh, Yong Kweon
    • Journal of Advanced Marine Engineering and Technology
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    • v.37 no.8
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    • pp.893-904
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    • 2013
  • In this paper, a Kriging metamodel-based multi-objective optimization strategy in conjunction with an NSGA-II(non-dominated sorted genetic algorithm-II) has been employed to optimize the valve-plate shape of the axial piston pump utilizing 3D CFD simulations. The optimization process for minimum pressure ripple and maximum pump efficiency is composed of two steps; (1) CFD simulation of the piston pump operation with various combination of six parameters selected based on the optimization principle, and (2) applying a multi-objective optimization approach based on the NSGA-II using the CFD data set to evaluate the Pareto front. Our exploration shows that we can choose an optimal trade-off solution combination to reach a target efficiency of the axial piston pump with minimum pressure ripple.

A STUDY ON CONSTRAINED EGO METHOD FOR NOISY CFD DATA (Noisy 한 CFD 결과에 대한 구속조건을 고려한 EGO 방법 연구)

  • Bae, H.G.;Kwon, J.H.
    • Journal of computational fluids engineering
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    • v.17 no.4
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    • pp.32-40
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    • 2012
  • Efficient Global Optimization (EGO) method is a global optimization technique which can select the next sample point automatically by infill sampling criteria (ISC) and search for the global minimum with less samples than what the conventional global optimization method needs. ISC function consists of the predictor and mean square error (MSE) provided from the kriging model which is a stochastic metamodel. Also the constrained EGO method can minimize the objective function dealing with the constraints under EGO concept. In this study the constrained EGO method applied to the RAE2822 airfoil shape design formulated with the constraint. But the noisy CFD data caused the kriging model to fail to depict the true function. The distorted kriging model would make the EGO deviate from the correct search. This distortion of kriging model can be handled with the interpolation(p=free) kriging model. With the interpolation(p=free) kriging model, however, the search of EGO solution was stalled in the narrow feasible region without the chance to update the objective and constraint functions. Then the accuracy of EGO solution was not good enough. So the three-step search method was proposed to obtain the accurate global minimum as well as prevent from the distortion of kriging model for the noisy constrained CFD problem.

Optimum Design of Composite Structures using Metamodels (메타모델을 이용한 복합재료 구조물의 최적 설계)

  • 이재훈;강지호;홍창선;김천곤
    • Composites Research
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    • v.16 no.4
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    • pp.36-43
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    • 2003
  • In this research, the optimization of composite structures was performed using metamodels. The optimization of composite structures requires a lot of time when optimizing the result of the time-consuming analysis. Thus, metamodels are used to replace the time-consuming analysis with simple models. RSM, kriging and neural networks are widely used metamodels. RSM and kriging were used in this study. The ultimate failure load analysis of the composite structure was approximated by metamodels. The optimizations of the composite plate were performed to maximize ultimate failure load using genetic algorithm and metamodels.

Efficient Adaptive Global Optimization for Constrained Problems (구속조건이 있는 문제의 적응 전역최적화 효율 향상에 대한 연구)

  • Ahn, Joong-Ki;Lee, Ho-Il;Lee, Sung-Mhan
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.38 no.6
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    • pp.557-563
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    • 2010
  • This paper addresses the issue of adaptive global optimization using Kriging metamodel known as EGO(Efficient Global Optimization). The algorithm adaptively chooses where to generate subsequent samples based on an explicit trade-off between reduction of global uncertainty and exploration of the region of the interest. A strategy that saves the computational cost by using expectations derived from probabilistic nature of approximate model is proposed. At every iteration, a candidate test point that seems to be feasible/inactive or has little possibility to improve for minimum is identified and excluded from updating approximate models. By doing that the computational cost is saved without loss of accuracy.

Optimal Rotor Structure Design of Interior Permanent Magnet Synchronous Machine based on Efficient Genetic Algorithm Using Kriging Model

  • Woo, Dong-Kyun;Kim, Il-Woo;Jung, Hyun-Kyo
    • Journal of Electrical Engineering and Technology
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    • v.7 no.4
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    • pp.530-537
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    • 2012
  • In the recent past, genetic algorithm (GA) and evolutionary optimization scheme have become increasingly popular for the design of electromagnetic (EM) devices. However, the conventional GA suffers from computational drawback and parameter dependency when applied to a computationally expensive problem, such as practical EM optimization design. To overcome these issues, a hybrid optimization scheme using GA in conjunction with Kriging is proposed. The algorithm is validated by using two mathematical problems and by optimizing rotor structure of interior permanent magnet synchronous machine.

Structural Design of a Circumferential Friction Disc-brake, Considering Thermoelastic Instability (열탄성 불안정성을 고려한 원주면 마찰형 디스크 브레이크의 구조설계)

  • Song, Byoung-Cheol;Kang, Dong-Heon;Kim, Young-Hee;Park, Young-Chul;Lee, Kwon-Hee
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.6 no.3
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    • pp.38-46
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    • 2007
  • Weight reduction for an automobile component has been sought to achieve fuel efficiency and energy conservation. In response to this trend, a new disc-brake called the circumferential friction disc-brake is suggested. This paper compares the mechanical performances of a conventional disc-brake and a suggested disc-brake, under the dynamic braking condition. The thermoelastic instability is considered to simulate the test condition. Furthermore, the metamodel using kriging interpolation method is introduced to obtain the optimum design of a suggested circumferential friction disc-brake. The design results obtained by the kriging method are compared with those obtained by the ANSYS.

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