• 제목/요약/키워드: Approximation component

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SIZE DISTRIBUTION OF ONE CONNECTED COMPONENT OF ELLIPTIC RANDOM FIELD

  • Alodat, M.T.
    • Journal of the Korean Statistical Society
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    • 제36권4호
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    • pp.479-488
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    • 2007
  • The elliptic random field is an extension to the Gaussian random field. We proved a theorem which characterizes the elliptic random field. We proposed a heuristic approach to derive an approximation to the distribution of the size of one connected component of its excursion set above a high threshold. We used this approximation to approximate the distribution of the largest cluster size. We used simulation to compare the approximation with the exact distribution.

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

  • 박찬우;이효성;김창곤
    • 대한산업공학회지
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    • 제28권1호
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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.

Sensitivity Analysis in Principal Component Regression with Quadratic Approximation

  • Shin, Jae-Kyoung;Chang, Duk-Joon
    • Journal of the Korean Data and Information Science Society
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    • 제14권3호
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    • pp.623-630
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    • 2003
  • Recently, Tanaka(1988) derived two influence functions related to an eigenvalue problem $(A-\lambda_sI)\upsilon_s=0$ of real symmetric matrix A and used them for sensitivity analysis in principal component analysis. In this paper, we deal with the perturbation expansions up to quadratic terms of the same functions and discuss the application to sensitivity analysis in principal component regression analysis(PCRA). Numerical example is given to show how the approximation improves with the quadratic term.

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Wavelet Transform을 이용한 감조하천 수위자료의 유출성분 추출 (Extraction of Runoff Component from Stage in Tidal River Using Wavelet Transform)

  • 오창열;이진원;정성원;박성천
    • 한국수자원학회논문집
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    • 제40권10호
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    • pp.793-800
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    • 2007
  • 본 연구는 조석의 영향을 받는 하동2 지점의 수위자료로부터 시간과 주파수 영역에서 유연한 분해능을 갖는 웨이블렛 변환을 적용하여 강우에 의한 유출성분과 조석에 의한 조위성분을 추출하였다. 최종파형 분해단계의 근사성분은 가장 큰 에너지 값은 87.77%를 나타내었으며, 상세성분 중 반일주조형의 주기성(약 12시간)을 갖는 D3의 에너지 값은 10.70%로 나타났다. 또한 D3의 왜도 및 첨도 값은 여수 조위자료와 유사함을 보여주었다. 따라서 하동2 지점의 수위자료에 대하여 최종 분해된 최종파형 분해단계의 근사성분(A6)과 D6, D5 상세성분은 유출성분이며, 상세성분 D4, D3, D2는 조석의 영향으로 수위가 상승과 하강을 반복하는 조위성분인 것으로 나타났다.

수질 및 강우자료의 상관분석을 위한 웨이블렛 변환의 적용 (Application of Wavelet Transform for Correlation Analysis between Water Quality and Rainfall Data)

  • 진영훈;오창열;박성천
    • 한국물환경학회지
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    • 제22권5호
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    • pp.831-837
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    • 2006
  • The present study applies wavelet transform for the extraction of various periodicities which are included in TOC and pH time series of water quality and rainfall data. The primary objective of the present study is to detect the relationships between the respective data through the correlation analysis using the approximation components which are decomposed by wavelet transform. The results reveal the approximation components of TOC and pH in the 5th level of wavelet transform can explain more than 99% of the whole energy for the raw data respectively and there are considerably high correlation between the approximation components of the respective data used for the study even through no significant correlation between the raw data has been detected.

웨이블렛 변환과 인공신경망을 이용한 일 TOC 자료의 예측에 관한 연구 (Study on the Prediction of Daily TOC Data by Using Wavelet Transform and Artificial Neural Networks)

  • 곽필정;오창열;진영훈;박성천
    • 한국물환경학회지
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    • 제22권5호
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    • pp.952-957
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    • 2006
  • The present study applied wavelet transform and artificial neural networks (ANNs) for the prediction of daily TOC data. TOC data were transformed into denoised data by the wavelet transform and the noise-reduced data were used for the prediction model by artificial neural networks. For the application of wavelet transform, Daubechies wavelet of order 10 ('db10') was used as a basis function and decomposed the TOC data up to fifth level with five detail components and one approximation component. ANNs were calibrated with the input data of the segregated TOC data corresponding to the details from second to fifth level and the approximation. Consequently, the ANNs model for the prediction of daily TOC data showed the best result when it had seventeen hidden nodes in its layer.

Numerical Investigations in Choosing the Number of Principal Components in Principal Component Regression - CASE I

  • Shin, Jae-Kyoung;Moon, Sung-Ho
    • Journal of the Korean Data and Information Science Society
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    • 제8권2호
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    • pp.127-134
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    • 1997
  • A method is proposed for the choice of the number of principal components in principal component regression based on the predicted error sum of squares. To do this, we approximately evaluate that statistic using a linear approximation based on the perturbation expansion. In this paper, we apply the proposed method to various data sets and discuss some properties in choosing the number of principal components in principal component regression.

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A Study on the Equivalent Model of an External Electrode Fluorescent Lamp Based on Equivalent Resistance and Capacitance Variation

  • Cho, Kyu-Min;Oh, Won-Sik;Moon, Gun-Woo;Park, Mun-Soo;Lee, Sang-Gil
    • Journal of Power Electronics
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    • 제7권1호
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    • pp.38-43
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    • 2007
  • An External Electrode Fluorescent Lamp (EEFL) has longer lifespan, higher power efficiency and higher luminance than a Cold Cathode Fluorescent Lamp (CCFL). Moreover, it is easy to drive them in parallel. Therefore, the EEFL is expected to quickly replace the CCFL in LCD backlight systems. However, the EEFL has more complex characteristics than the CCFL with a resistive component, because it has both a resistive component by plasma and a capacitive component by external electrode. In this paper, values of resistance and capacitance are measured at several power levels and at several operating frequencies. They are expressed by a numeral formula based on a linear approximation that represents the equivalent resistance and capacitance as a function of power. Then we made block diagram of the equivalent circuit model using numerical expressions. Simulation waveforms and experimental results are presented to verify the feasibility of the equivalent model.

영산강 유역의 유출량 및 수질자료에 대한 비선형 동역학과 웨이블렛 이론의 적용 (Application of Nonlinear Dynamics and Wavelet Theory for Discharge and Water Quality Data in Youngsan River Basin)

  • 오창열;진영훈;박성천
    • 한국물환경학회지
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    • 제23권4호
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    • pp.551-560
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    • 2007
  • The present study analyzed noise reduction and long/short-term components for discharge, TOC concentration, and TOC load data in order to understand the data characteristics better. For the purpose, wavelet transform which can reduce noise from raw data and has flexible resolution in time and frequency domain was applied and the theory of nonlinear dynamics was also used to determine the last decomposition level for wavelet transform. Wavelet function of 'db10' and the 7th level for the last decomposition of wavelet transform were applied for the all data in the present study. Also the results revealed that the energy ratios of approximation components with 187-hour periodicity decomposed from 7th level of wavelet transform were 94.71% (discharge), 99.00% (TOC concentration), and 93.84% (TOC load), respectively. In addition, the energy ratios of detail components showed the range between 1.00% and 6.17%, which were extremely small comparing to the energy ratios of approximation components, therefore, the first and second detail components might be considered as noise components included in the raw data.

진화퍼지 근사화모델에 의한 비선형 구조시스템의 최적설계 (Optimal Design of Nonlinear Structural Systems via EFM Based Approximations)

  • 이종수;김승진
    • 한국지능시스템학회:학술대회논문집
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    • 한국퍼지및지능시스템학회 2000년도 춘계학술대회 학술발표 논문집
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    • pp.122-125
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    • 2000
  • The paper describes the adaptation of evolutionary fuzzy model ins (EFM) in developing global function approximation tools for use in genetic algorithm based optimization of nonlinear structural systems. EFM is an optimization process to determine the fuzzy membership parameters for constructing global approximation model in a case where the training data are not sufficiently provided or uncertain information is included in design process. The paper presents the performance of EFM in terms of numbers of fuzzy rules and training data, and then explores the EFM based sizing of automotive component for passenger protection.

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