• Title/Summary/Keyword: robust model

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Deriving Robust Reservoir Operation Policy under Changing Climate: Use of Robust Optimiziation with Stochastic Dynamic Programming

  • Kim, Gi Joo;Kim, Young-Oh
    • 한국수자원학회:학술대회논문집
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    • 한국수자원학회 2020년도 학술발표회
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    • pp.171-171
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    • 2020
  • Decision making strategies should consider both adaptiveness and robustness in order to deal with two main characteristics of climate change: non-stationarity and deep uncertainty. Especially, robust strategies are different from traditional optimal strategies in the sense that they are satisfactory over a wider range of uncertainty and may act as a key when confronting climate change. In this study, a new framework named Robust Stochastic Dynamic Programming (R-SDP) is proposed, which couples previously developed robust optimization (RO) into the objective function and constraint of SDP. Two main approaches of RO, feasibility robustness and solution robustness, are considered in the optimization algorithm and consequently, three models to be tested are developed: conventional-SDP (CSDP), R-SDP-Feasibility (RSDP-F), and R-SDP-Solution (RSDP-S). The developed models were used to derive optimal monthly release rules in a single reservoir, and multiple simulations of the derived monthly policy under inflow scenarios with varying mean and standard deviations are undergone. Simulation results were then evaluated with a wide range of evaluation metrics from reliability, resiliency, vulnerability to additional robustness measures. Evaluation results were finally visualized with advanced visualization tools that are used in multi-objective robust decision making (MORDM) framework. As a result, RSDP-F and RSDP-S models yielded more risk averse, or conservative, results than the CSDP model, and a trade-off relationship between traditional and robustness metrics was discovered.

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다목적 시스템식별을 이용한 모우드 불확실성이 있는 구조물의 강인 최적 감쇠기 설계 (Robust Optimal Damper Design of Structures with Modal Uncertainty Using Multi-Objective System Identification)

  • 정성운;옥승용;박원석;고현무
    • 한국안전학회지
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    • 제27권1호
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    • pp.76-85
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    • 2012
  • This paper proposes a robust damper design technique for adjacent structures against model uncertainty. This approach introduces multi-objective optimization based system identification using measurement information which enables reasonable selection of the perturbation range in the robust design. Moreover, in order to improve the numerical efficiency in sampling the structural models required for the robust design of large structures, we define new objective functions which enable us to minimize the number of candidate models suitable to the purpose of the robust design. In addition, the performance index is newly employed to evaluate the robust performance of the sampled structural models, and the robust design has been performed according to the performance index. As a numerical example to demonstrate the efficiency of the proposed method, 5-story and 10-story two adjacent buildings are taken into account, and the existing and newly proposed robust design approaches are compared with each other. The results demonstrate that the proposed approach can guarantee more robust damper system only using small number of samples of the structural models because of using the measurement information which leads to improvement in the numerical efficiency, compared with the existing robust design methods.

An Efficient Model Parameter Compensation Method foe Robust Speech Recognition

  • 정용주
    • 대한음성학회지:말소리
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    • 제45호
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    • pp.107-115
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    • 2003
  • An efficient method that compensates the HMM parameters for the noisy speech recognition is proposed. Instead of assuming some analytical approximations as in the PMC, the proposed method directly re-estimates the HMM parameters by the segmental k-means algorithm. The proposed method has shown improved results compared with the conventional PMC method at reduced computational cost.

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실용적인 혼합물 성분 공정변수 실험설계 (Practical designs for mixture component-process experiments)

  • 임용빈
    • 품질경영학회지
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    • 제39권3호
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    • pp.400-411
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    • 2011
  • Process variables are factors in an experiment that are not mixture components but could affect the blending properties of the mixture ingredients. For example, the effectiveness of an etching solution which is measured as an etch rate is not only a function of the proportions of the three acids that are combined to form the mixture, but also depends on the temperature of the solution and the agitation rate. Efficient designs for the mixture components-process variables experiments depend on the mixture components-process variables model which is called a combined model. We often use the product model between the canonical polynomial model for the mixture and process variables model as a combined model. In this paper we propose three starting models for the mixture components-process variables experiments. One of the starting model we are considering is the model which includes product terms up to cubic order interactions between mixture effects and the linear & pure quadratic effect of the process variables from the product model. In this paper, we propose a method for finding robust designs and practical designs with respect to D-, G-, and I-optimality for the various starting combined models and then, we find practically efficient and robust designs for estimating the regression coefficients for those models. We find the prediction capability of those recommended designs in the case of three components and three process variables to be good by checking FDS(Fraction of Design Space) plots.

Decentralized Nonlinear Voltage Control of Multi-machine Power Systems with Nonlinear Interconnections

  • Lee, Jae-Won;Yoon, Tae-Woong;Im, Sun
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2004년도 ICCAS
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    • pp.448-453
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    • 2004
  • In this paper, an adaptive robust decentralized excitation control scheme is proposed to enhance the transient stability of a multi-machine power system. We employ a state model where the terminal voltage of each generator is regarded as part of the state. Using this state model, the proposed controller is obtained in two steps: firstly, a robust controller is designed for the nominal system with no interconnection terms; then an adaptive compensator is proposed to deal with those interconnection terms, whose upper bounds are estimated. The resulting adaptive scheme guarantees the practical stability of the closed-loop, and also the uniform ultimate boundedness in the presence of disturbances.

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Voting based Cue Integration for Visual Servoing

  • Cho, Che-Seung;Chung, Byeong-Mook
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2003년도 ICCAS
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    • pp.798-802
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    • 2003
  • The robustness and reliability of vision algorithms is the key issue in robotic research and industrial applications. In this paper, the robust real time visual tracking in complex scene is considered. A common approach to increase robustness of a tracking system is to use different models (CAD model etc.) known a priori. Also fusion of multiple features facilitates robust detection and tracking of objects in scenes of realistic complexity. Because voting is a very simple or no model is needed for fusion, voting-based fusion of cues is applied. The approach for this algorithm is tested in a 3D Cartesian robot which tracks a toy vehicle moving along 3D rail, and the Kalman filter is used to estimate the motion parameters, namely the system state vector of moving object with unknown dynamics. Experimental results show that fusion of cues and motion estimation in a tracking system has a robust performance.

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기하학적 특징 모델을 이용한 강건한 영상 모자이크 기법 (Robust Image Mosaic using Geometrical Feature Model)

  • 김정훈;김대현;윤용인;최종수
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2000년도 추계종합학술대회 논문집(4)
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    • pp.13-16
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    • 2000
  • This paper presents a robust method to combine a collection of images with small fields of view to obtain an image with a large field of view. In the previous works, there are two main areas which one is a cross correlation-based method and the other is a feature-based method. The former is based on motion estimation from video sequences. so there are a problem on rotating a camera about optical axis. In the latter method, it is difficult to match correspondence feature points correctly.'re find correct correspondences, we proposed the geometrical feature model and correspondence filters and the Gaussian distribution weight function to blend the images smoothly. The experiments show that our method is robust and effective.

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다구찌 방법(方法)을 이용한 경제적(經濟的) 발주량(發注量)의 안정성(安定性) 설계(設計) (Determination of a Robust Economic Order Quantity Using Taguchi Method)

  • 최종덕;서순근
    • 품질경영학회지
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    • 제20권1호
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    • pp.68-79
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    • 1992
  • The economic order quantity(EOQ) is a robust quantity, and it is largely insensitive to reasonable errors in the estimation of most of its parameters. Optimal EOQ and reorder point which are not sensitive to the estimates of the various cost model parameters for Kim and Park's model are determined. This of Taguchi's parameter design which finds a robust EOQ and reorder point using reasonable cost structure on the assumption of normally distributed quality characteristic. A numerical example is also presented to illustrate the proposed procedure and computer aided numerical experiments for selected values of backordered fractions and standard deviations are performed.

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