• Title/Summary/Keyword: variance errors.

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Power Analysis for Tests Adjusted for Measurement Error

  • Heo, Sun-Yeong;Eltinge, John L.
    • 한국데이터정보과학회:학술대회논문집
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    • 2003.05a
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    • pp.1-14
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    • 2003
  • In man cases, the measurement error variances may be functions of the unknown true values or related covariate. In some cases, the measurement error variances increase in proportion to the value of predictor. This paper develops estimators of the parameters of a linear measurement error variance function under stratified multistage random sampling design and additional conditions. Also, this paper evaluates and compares the power of an asymptotically unbiased test with that of an asymptotically biased test. The proposed method are applied to blood sample measurements from the U.S. Third National Health and Nutrition Examination Survey(NHANES III)

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A Study on the Speciman For High Speed Machining (고속가공을 위한 검사시편에 관한 연구)

  • 정종윤;황영수;이춘만;정원지;고태조
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.12 no.4
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    • pp.77-84
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    • 2003
  • The properties of a machine tool greatly affect machining quality since a machine tool has large variance in its features. Machine tool makers want to find best machining condition with the one that they have built. Machine builders need to develop test specimen since it helps finding characteristics of machine tools when the machining properties of the specimen are analyzed. This paper develops test specimen to identify features of the main spindle, the feeding device, and the frame of a machine tool. The specimen is machined with a high speed machine and the features of the machine are analyzed with test items. They are surface roughness, overshoot in axial movement, errors in circular movement, feeding with small movement and compensational error. This work can improve usability for a machine tool in machining practice.

An Experimental Study on Engineering Properties of High-Strength Concrete by Revision Error of the Ratio of Surface Moisture in Fine Aggregate (잔골재의 표면수율 보정오차에 따른 고강도콘크리트의 공학적 특성에 관한 실험적 연구)

  • Kang, Suk-Pyo;Jang, Jong-Ho;Park, Yong-Mock;Lee, Seung-Hoon;Yu, Jae-Chul;Kim, Moo-Han
    • Proceedings of the Korea Concrete Institute Conference
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    • 2000.04a
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    • pp.53-56
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    • 2000
  • The performance of high-strength concrete is controlled by the fact, affecting the quality management, especially by revision error in water content of the ratio of surface moisture in fine aggregate. The difference in water content results from the revision error of the ratio of surface moisture and errors in sampled aggregate in the processing ready-mixed concrete plant. This study is to investigate the properties of flowing and hardening by investionally varying the revision error of the ratio of surface moisture in fine aggregate to compare and analyze the variance in quality.

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An Optimal FIR Filter for Discrete Time-varying State Space Models (이산 시변 상태공간 모델을 위한 최적 유한 임펄스 응답 필터)

  • Kwon, Bo-Kyu
    • Journal of Institute of Control, Robotics and Systems
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    • v.17 no.12
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    • pp.1183-1187
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    • 2011
  • In this paper, an optimal FIR (Finite-Impulse-Response) filter is proposed for discrete time-varying state-space models. The proposed filter estimates the current state using measured output samples on the recent time horizon so that the variance of the estimation error is minimized. It is designed to be linear, unbiased, with an FIR structure, and is independent of any state information. Due to its FIR structure, the proposed filter is believed to be robust for modeling uncertainty or numerical errors than other IIR filters, such as the Kalman filter. For a general system with system and measurement noise, the proposed filter is derived without any artificial assumptions such as the nonsingular assumption of the system matrix A and any infinite covariance of the initial state. A numerical example show that the proposed FIR filter has better performance than the Kalman filter based on the IIR (Infinite- Impulse-Response) structure when modeling uncertainties exist.

Robust Optimization of a Lens System for a Mobile Phone Camera (휴대폰 카메라용 렌즈 시스템의 강건최적설계)

  • Jung, Sang-Jin;Min, Jun-Hong;Choi, Dong-Hoon;Kim, Ju-Ho
    • Korean Journal of Computational Design and Engineering
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    • v.15 no.5
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    • pp.325-332
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    • 2010
  • A lens system for mobile phone cameras is comprised of various lenses and designed so as to satisfy design requirements for responses such as a modular transfer function (MTF). However, it is difficult to manufacture and assemble camera modules to maintain the same performance compared with the designed camera modules, because of uncertainty. We should always design a lens system by considering uncertainty that can be caused by errors in the manufacturing and assembly process of mobile phone cameras. The robust optimization offers tools of making robust decisions with the consideration of design parameters, uncontrollable parameters, and the variance of the system. Using an efficient reliability analysis method and an optimization algorithm, we obtained robust optimization results that maximize the mean of MTF and minimize the standard deviation and proposed a new robust design process for a lens system.

A Study on the Evaluative Method of Workability For High Speed Machining (고속가공기의 가공성 평가방법에 관한 연구)

  • Lee, Choon-Man;Ryu, Sung-Pyo;Hwang, Young-Su;Chung, Won-Jee;Jung, Jong-Yun;Ko, Tae-Jo
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.1858-1863
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    • 2003
  • The properties of a machine tool greatly affect machining quality since a machine tool has large variance in its features. Machine tool makers want to find best machining condition with the one that they have built. Machine builders need to develop test specimen since it helps finding characteristics of machine tools when the machining properties of the specimen are analyzed. This paper develops test specimen to identify features of the main spindle, the feeding device, and the frame of a machine tool. The specimen is machined with a high speed machine and the features of the machine are analyzed with test items. They are surface roughness, overshoot in axial movement, errors in circular movement, feeding with small movement, and compensational error. This work can improve usability for a machine tool in machining practice.

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Estimating Prediction Errors in Binary Classification Problem: Cross-Validation versus Bootstrap

  • Kim Ji-Hyun;Cha Eun-Song
    • Communications for Statistical Applications and Methods
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    • v.13 no.1
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    • pp.151-165
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    • 2006
  • It is important to estimate the true misclassification rate of a given classifier when an independent set of test data is not available. Cross-validation and bootstrap are two possible approaches in this case. In related literature bootstrap estimators of the true misclassification rate were asserted to have better performance for small samples than cross-validation estimators. We compare the two estimators empirically when the classification rule is so adaptive to training data that its apparent misclassification rate is close to zero. We confirm that bootstrap estimators have better performance for small samples because of small variance, and we have found a new fact that their bias tends to be significant even for moderate to large samples, in which case cross-validation estimators have better performance with less computation.

The Influence of Electric Noise for Decrepit Vehicle (전기 노이즈가 노후 차량에 미치는 영향)

  • Choi, Nyeonsik
    • The Transactions of the Korean Institute of Power Electronics
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    • v.22 no.5
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    • pp.382-389
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    • 2017
  • The development of electronic technology has been rapidly achieved in the automotive industry. A trend that attaches electric equipment, including ECUs at vehicles, is observed. However, decrepit vehicles have several electrical noises and errors. The effect of electric noise on vehicles that are focused on smoke was investigated. Many researchers have argued that one of the reasons of the occurrence of smoke in vehicles is the inexact time of the occurrence of ignition. Moreover, various physical, chemical, and thermodynamic solutions were attempted to approach and many improvements were accomplished. However, in this study, the reduction of electrical and electronic noise is confirmed to improve the accuracy of the injection time on decrepit vehicles with electrical and electric technologies. Previous studies suggest that the distance between the pilot and main ignitions affect the occurrence of smoke and control the variance value of the distance between pilot and main ignitions with electric filter. Thus, the effect of reducing smoke occurred.

Review on Application Tolerance of Unit Hydrograph for Calculating Flood Runoff Hydrograph (홍수 유출 수문곡선 산출에 단위유량도 적용 오차의 정도 검토)

  • Yoo, Ju-Hwan;Yoon, Yeo-Jin
    • Proceedings of the Korea Water Resources Association Conference
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    • 2010.05a
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    • pp.346-349
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    • 2010
  • In this study several unit hydrographs by rainfall storms are derived and moving averaged unit hydrograph is extracted from them based on the rainfall-runoff data in a small basin 8.5 $km^2$ wide. And peak discharges and peak times of the unit hydrographs are investigated and reviewed. And then a representative unit hydrograph of the moving averaged one is applied to the linear convolution integration for obtaining the flood discharge hydrograph and peak discharge and time of its result are researched and inspected. Variance in application of the representative unit hydrograph in a basin on assumption of linearity is appeared and this is given as a counterevidence about that the runoff response from rainfall on a basin has nonlinear characteristics. And As a result of application of derived representative unit hydrograph the errors in peak discharge and time are investigated.

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Estimation of Reliability for a Parallel System with Dependent Exponential Components (종속 지수 성분을 가지는 병렬시스템의 신뢰도 추정)

  • 안정향;윤상철
    • Journal of Korea Society of Industrial Information Systems
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    • v.8 no.4
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    • pp.94-100
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    • 2003
  • In this paper, we study the estimation of reliability function for a parallel system with k dependent exponential components. We assume that the failure of one of the k components changes the life distribution of the remaining components. Also, we compare with Cramer-Rna lower bound for variances of the minimum variance unbiased estimator, and the mean square errors of the maximum likelihood estimator of reliability system with the through the Monte Carlo simulation.

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