• Title/Summary/Keyword: approximation technique

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Repetitive Response Surface Enhancement Technique Using ResponseSurface Sub-Optimization and Design Space Transformation (반응모델 최적화와 설계공간 변환을 이용한 반복적 반응면 개선 기법 연구)

  • Jeon, Gwon-Su;Lee, Jae-U;Byeon, Yeong-Hwan
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.1
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    • pp.42-48
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    • 2006
  • In this study, a repetitive response surface enhancement technique (RRSET) is proposed as a new system approximation method for the efficient multidisciplinary design and optimization (MDO). In order to represent the highly nonlinear behavior of the response with second order polynomials, RRSET introduces a design space transformation using stretching functions and repetitive response surface improvement. The tentative optimal point is repetitively included to the set of experimental points to better approximate the response surface of the system especially near the optimal point, hence a response surface with significantly improved accuracy can be generated with very small experimental points and system iterations. As a system optimizer, the simulated annealing, which generates a global design solution is utilized. The proposed technique is applied to several numerical examples, and demonstrates the validity and efficiency of the method. With its improved approximation accuracy, the RRSET can contribute to resolve large and complex system design problems under MDO environment.

A Low Power SAR ADC with Enhanced SNDR for Sensor Application (신호 대 잡음비가 향상된 센서 신호 측정용 저 전력 SAR형 A/D 변환기)

  • Jung, Chan-Kyeong;Lim, Shin-Il
    • Journal of Sensor Science and Technology
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    • v.27 no.1
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    • pp.31-35
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    • 2018
  • This paper describes a low-power, SNDR (signal-to-noise and distortion ration) enhanced SAR (successive approximation register) type 12b ADC (analog-to-digital converter) with noise shaping technique. For low power consumption and small chip size of the DAC (digital-to-analog converter), the top plate sampling technique and the dummy capacitor switching technique are used to implement 12b operation with a 10b capacitor array in DAC. Noise shaping technique is applied to improve the SNDR by reducing the errors from the mismatching of DAC capacitor arrays, the errors caused by attenuation capacitor and the errors from the comparator noise. The proposed SAR ADC is designed with a $0.18{\mu}m$ CMOS process. The simulation results show that the SNDR of the SAR ADC without the noise shaping technique is 71 dB and that of the SAR ADC with the noise shaping technique is 84 dB. We can achieve the 13 dB improvement in SNDR with this noise shaping technique. The power consumption is $73.8{\mu}W$ and the FoM (figure-of-merit) is 5.2fJ/conversion-step.

On the Modified Supplementary Variable Technique for a Discrete-Time GI/G/1 Queue with Multiple Vacations (복수휴가형 이산시간 GI/G/1 대기체계에 대한 수정부가변수법)

  • Lee, Doo Ho
    • Journal of Korean Institute of Industrial Engineers
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    • v.42 no.5
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    • pp.304-313
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    • 2016
  • This work suggests a new analysis approach for a discrete-time GI/G/1 queue with multiple vacations. The method used is called a modified supplementary variable technique and our result is an exact transform-free expression for the steady state queue length distribution. Utilizing this result, we propose a simple two-moment approximation for the queue length distribution. From this, approximations for the mean queue length and the probabilities of the number of customers in the system are also obtained. To evaluate the approximations, we conduct numerical experiments which show that our approximations are remarkably simple yet provide fairly good performance, especially for a Bernoulli arrival process.

DETECTION AND COUNTING OF FLOWERS BASED ON DIGITAL IMAGES USING COMPUTER VISION AND A CONCAVE POINT DETECTION TECHNIQUE

  • PAN ZHAO;BYEONG-CHUN SHIN
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.27 no.1
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    • pp.37-55
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    • 2023
  • In this paper we propose a new algorithm for detecting and counting flowers in a complex background based on digital images. The algorithm mainly includes the following parts: edge contour extraction of flowers, edge contour determination of overlapped flowers and flower counting. We use a contour detection technique in Computer Vision (CV) to extract the edge contours of flowers and propose an improved algorithm with a concave point detection technique to find accurate segmentation for overlapped flowers. In this process, we first use the polygon approximation to smooth edge contours and then adopt the second-order central moments to fit ellipse contours to determine whether edge contours overlap. To obtain accurate segmentation points, we calculate the curvature of each pixel point on the edge contours with an improved Curvature Scale Space (CSS) corner detector. Finally, we successively give three adaptive judgment criteria to detect and count flowers accurately and automatically. Both experimental results and the proposed evaluation indicators reveal that the proposed algorithm is more efficient for flower counting.

A Square-Root Forward Backward Correlation-based Projection Approximation for Subspace Tracking (신호부공간 추정 성능 향상을 위한 전후방 상관과 제곱근행렬 갱신을 이용한 COPAST(correlation-based projection approximation for subspace-tracking) 알고리즘 연구)

  • Lim, June-Seok;Pyeon, Yong-Kug
    • 전자공학회논문지 IE
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    • v.48 no.1
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    • pp.7-15
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    • 2011
  • In this paper, we propose a correlation-based subspace estimation technique, which is called square-root forward/backward correlation-based projection approximation subspace tracking(SRFB-COPAST). The SRFB-COPAST utilizes the forward and backward correlation matrix as well as square-root recursive matrix update in projection approximation approach to develop the subspace tracking algorithm. With the projection approximation, the square-root recursive FB-COPAST is presented. The proposed algorithm has the better performance than the recently developed COPAST method.

Influence of the Diagonal Dominance of Modal Damping Matrix on the Decoupling Approximation (모드 댐핑 행렬의 대각선 성분 우세가 비연관화 근사에 미치는 영향)

  • 김정수;최기흥;최기상
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.8
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    • pp.1963-1970
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    • 1993
  • A simple technique to decouple the modal equations of motion of a linear nonclassically damped system is to neglect the off-diagonal elements of the modal damping matrix. This is called the decoupling approximation. It has generally been conceived that smallness of off-diagonal elements relative to the diagonal ones would validate its use. In this study, the relationship between elements of the modal damping matrix and the error arising from the decoupling approximation is explored. It is shown that the enhanced diagonal dominance of the modal damping matrix need not diminish the error. In fact, the error may even increase. Moreover, the error is found to be strongly dependent on the exitation. Therefore, within the practical range of engineering applications, diagonal dominance of the modal damping matrix would not be sufficient to supress the effect of modal coupling.

Kernel Adatron Algorithm of Support Vector Machine for Function Approximation (함수근사를 위한 서포트 벡터 기계의 커널 애더트론 알고리즘)

  • Seok, Kyung-Ha;Hwang, Chang-Ha
    • The Transactions of the Korea Information Processing Society
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    • v.7 no.6
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    • pp.1867-1873
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    • 2000
  • Function approximation from a set of input-output pairs has numerous applications in scientific and engineering areas. Support vector machine (SVM) is a new and very promising classification, regression and function approximation technique developed by Vapnik and his group at AT&TG Bell Laboratories. However, it has failed to establish itself as common machine learning tool. This is partly due to the fact that this is not easy to implement, and its standard implementation requires the use of optimization package for quadratic programming (QP). In this appear we present simple iterative Kernel Adatron (KA) algorithm for function approximation and compare it with standard SVM algorithm using QP.

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Performance Evaluation of a Multi - Item Production System Operated by the CONWIP Control Mechanism (CONWIP 통제방식에 의해 운영되는 다품목 생산시스템의 성능평가)

  • Park, Chan-Woo;Lee, Hyo-Seong;Kim, Chang-Gon
    • Journal of Korean Institute of Industrial Engineers
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    • v.28 no.1
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    • pp.1-13
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    • 2002
  • We study a multi-component production/inventory system in which individual components are made to meet various demand types. We assume that the demands arrive according to a Poisson process, but there is a fixed probability that a demand requests a particular kit of different components. Each component is produced by a flow line with several stations. The production of each component is operated by the CONWIP control mechanism. To analyse this system, we propose an approximation method based on aggregation method. In application of the aggregation method, a product-form approximation technique as well as a matrix-geometric method is used. Comparisons with simulation show that the approximation method provides fairly good results.

Minimum Weight Design for Bridge Girder using Approximation based Optimization Method

  • ;Yearn-Tzuo(Andrew);Gar
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.37 no.E
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    • pp.31-39
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    • 1995
  • Weight minimization for the steel bridge girders using an approximation based optimization technique is presented. To accomplish this, an optimization oriented finite element program is used to achieve continuous weight reduction until the optimum is reached. To reduce computational cost, approximation techniques are adopted during the optimization process. Constraint deletion as well as intermediate design variables and responses are also used for higher qualitv of approximations and for a better convergence rate. Both the reliability and the effectiveness of the underlying optimization method are reviewed.

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A New Method for Approximation of Linear System in Frequency Domain (주파수영역에서 선형시스템 간략화를 위한 새로운 방법)

  • Kwon, Oh-Shin
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.24 no.4
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    • pp.583-589
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    • 1987
  • A new approximation method is proposed for the linear model reduction of high order dynamic systems. This mehtod is based upon the denominator table(D-table) and time moment-matching technique. The denominator table(D-table) is used to obtain the denominator polynomial of reduced-order model, and the numerator polynomial is obtained by time moment-matching method. This proposed method does not require the calculation of the alpha-beta expansion and reciprocal transformation which should be calculadted by Routh approximation method. The advantages of the proposed method are that it is computationally every attractive better than Routh approximation method and the reduced model is stable Il the original system is stable.

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