• Title/Summary/Keyword: 가중계수

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Flowrate Integration Errors of Multi-path Ultrasonic Flowmeter using Weighting Factors (가중계수에 의한 다회선 초음파 유량계의 유량적분오차)

  • Lee, Ho-June;Hwang, Shang-Yoon;Kim, Kyoung-Jin
    • 유체기계공업학회:학술대회논문집
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    • 2003.12a
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    • pp.154-160
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    • 2003
  • Multi-path ultrasonic flowrate measuring technology is being received much attentions from a variety of industrial fields to exactly measure the flowmeter. Multi-path ultrasonic flowmeter has much advantage since it has no moving parts and not occurred pressure loss. It offers good accuracy, repeatability, linearity and Tum-down ratio can measure over 1:50. The present study investigates flowrate integration errors using weighting factors. A theoretical flow model uses power law to describe a fully developed velocity profiles and wall roughness changes. The methods of weighting factor simulate three configurations of measuring location of gaussian, chebyshev and tailor method. The obtained results show that many chord arrangements are not affected for wall roughness changes and can measure accurate flowrate.

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A Graphical Method for Evaluating the Effect of Outliers in One- and Two-Variate Data (일변량 및 이변량 자료에 대하여 특이값의 영향을 평가하기 위한 그래픽 방법)

  • Jang, Dae-Heung
    • The Korean Journal of Applied Statistics
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    • v.20 no.2
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    • pp.395-407
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    • 2007
  • Outliers distort many measures for data analysis. We can propose dandelion seed plot as a graphical tool for evaluating the effect of outliers in one-and two-variate data. We can draw mean-variance dandelion seed plots using linked curves which are made by changing weights from 1 to 0 for each datum. Similarly we can also draw covariance-correlation-coefficient dandelion seed plots. This graphical method can be a useful tool for elementary statistics education in college.

Regression model for the preparation of calibration curve in the quantitative LC-MS/MS analysis of urinary methamphetamine, amphetamine and 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid using R (소변 중 메트암페타민, 암페타민 및 대마 대사체 LC-MS/MS 정량분석에서 검량선 작성을 위한 R을 활용한 회귀모델 선택)

  • Kim, Jin Young;Shin, Dong Won
    • Analytical Science and Technology
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    • v.34 no.6
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    • pp.241-250
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    • 2021
  • Calibration curves are essential in quantitative methods and for improving the accuracy of analyte measurements in biological samples. In this study, a statistical analysis model built in the R language (The R Foundation for Statistical Computing) was used to identify a set of weighting factors and regression models based on a stepwise selection criteria. An LC-MS/MS method was used to detect the presence of urinary methamphetamine, amphetamine, and 11-nor-9-carboxy-Δ9 -tetrahydrocannabinol in a sample set. Weighting factors for the calibration curves were derived by calculating the heteroscedasticity of the measurements, where the presence of heteroscedasticity was determined via variance tests. The optimal regression model and weighting factor were chosen according to the sum of the absolute percentage relative error. Subsequently, the order of the regression model was calculated using a partial variance test. The proposed statistical analysis tool facilitated selection of the optimal calibration model and detection of methamphetamine, amphetamine, and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol in urine. Thus, this study for the selection of weighting and the use of a complex regression equation may provide insights for linear and quadratic regressions in analytical and bioanalytical measurements.

A new Implementation of Perceptual LPC Cepstrum and its Application to Speech Recognition (인지 LPC cepstrum의 새로운 구현 및 음성인식에의 적용)

  • Kim, Jin-Young;Choi, Seong-Ho
    • The Journal of the Acoustical Society of Korea
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    • v.15 no.5
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    • pp.61-64
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    • 1996
  • To improve the performance of a recognition system, namely the recognition rate, we propose a hew implementation of perceptual distance using LPC cepstrum(perceptual cepstrum, PLC). The PLC is caculated by convolution of a usual LPC cepstrum and a perceptual lifter(PL). To caculate PL, we define a new weighting function in the linear frequency domain considering the frequency scale(Bark-scale) characteristics. The PL is the inverse Fourier transform of the exponents of the weighting function. We verified our method through the speech recognition experiments. The performance of PLC was compared with that of the rasied sine liftering method.

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The Joint Effect of factors on Generalization Performance of Neural Network Learning Procedure (신경망 학습의 일반화 성능향상을 위한 인자들의 결합효과)

  • Yoon YeoChang
    • The KIPS Transactions:PartB
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    • v.12B no.3 s.99
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    • pp.343-348
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    • 2005
  • The goal of this paper is to study the joint effect of factors of neural network teaming procedure. There are many factors, which may affect the generalization ability and teaming speed of neural networks, such as the initial values of weights, the learning rates, and the regularization coefficients. We will apply a constructive training algerian for neural network, then patterns are trained incrementally by considering them one by one. First, we will investigate the effect of these factors on generalization performance and learning speed. Based on these factors' effect, we will propose a joint method that simultaneously considers these three factors, and dynamically hue the learning rate and regularization coefficient. Then we will present the results of some experimental comparison among these kinds of methods in several simulated nonlinear data. Finally, we will draw conclusions and make plan for future work.

Weight Function Theory for Piezoelectric Materials with a Crack (균열을 가진 압전재료에서의 가중함수이론)

  • 손인호;안득만
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.7
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    • pp.208-216
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    • 2003
  • In this paper, a two-dimensional electroelastic analysis is performed on a piezoelectric material with an open crack. The approach of Lekhnitskii's complex potential functions is used in the derivation and Bueckner's weight function theory is extended to piezoelectric materials. The stress intensity factors and the electric displacement intensity factor are calculated by the weight function theory.

Determination of Thermal Shock Stress Intensity Factor for Elliptical Crack by Modified Vainshtok Weight Function Method (수정 Vainshtok 가중함수법에 의한 타원균열의 열충격 응력세기계수의 결정)

  • 이강용;김종성
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.2
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    • pp.463-474
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    • 1995
  • Modified Vainshtok weight function method is developed. The thermal shock stress intensity factors for elliptical surface cracks existed in the thin and thick walled cylinders are determined. The present results are compared with previous solutions and shown to be good agreement with them.

Weight Function Theory for Piezoelectric Materials with Crack in Anti-Plane Deformation (균열을 가진 압전재료에 대한 면외 변형에서의 가중함수이론)

  • Son, In-Ho;An, Deuk-Man
    • Journal of Ocean Engineering and Technology
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    • v.24 no.3
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    • pp.59-63
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    • 2010
  • In this paper, an electroelastic analysis is performed on a piezoelectric material with an open crack in anti-plane deformation. Bueckner’s weight function theory is extended to piezoelectric materials in anti-plane deformation. The stress intensity factors and electric displacement intensity factor are calculated by the weight function theory.

Design-based Properties of Least Square Estimators in Panel Regression Model (패널회귀모형에서 회귀계수 추정량의 설계기반 성질)

  • Kim, Kyu-Seong
    • Survey Research
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    • v.12 no.3
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    • pp.49-62
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    • 2011
  • In this paper we investigate design-based properties of both the ordinary least square estimator and the weighted least square estimator for regression coefficients in panel regression model. We derive formulas of approximate bias, variance and mean square error for the ordinary least square estimator and approximate variance for the weighted least square estimator after linearization of least square estimators. Also we compare their magnitudes each other numerically through a simulation study. We consider a three years data of Korean Welfare Panel Study as a finite population and take household income as a dependent variable and choose 7 exploratory variables related household as independent variables in panel regression model. Then we calculate approximate bias, variance, mean square error for the ordinary least square estimator and approximate variance for the weighted least square estimator based on several sample sizes from 50 to 1,000 by 50. Through the simulation study we found some tendencies as follows. First, the mean square error of the ordinary least square estimator is getting larger than the variance of the weighted least square estimator as sample sizes increase. Next, the magnitude of mean square error of the ordinary least square estimator is depending on the magnitude of the bias of the estimator, which is large when the bias is large. Finally, with regard to approximate variance, variances of the ordinary least square estimator are smaller than those of the weighted least square estimator in many cases in the simulation.

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Weighting Effect on the Weighted Mean in Finite Population (유한모집단에서 가중평균에 포함된 가중치의 효과)

  • Kim, Kyu-Seong
    • Survey Research
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    • v.7 no.2
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    • pp.53-69
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    • 2006
  • Weights can be made and imposed in both sample design stage and analysis stage in a sample survey. While in design stage weights are related with sample data acquisition quantities such as sample selection probability and response rate, in analysis stage weights are connected with external quantities, for instance population quantities and some auxiliary information. The final weight is the product of all weights in both stage. In the present paper, we focus on the weight in analysis stage and investigate the effect of such weights imposed on the weighted mean when estimating the population mean. We consider a finite population with a pair of fixed survey value and weight in each unit, and suppose equal selection probability designs. Under the condition we derive the formulas of the bias as well as mean square error of the weighted mean and show that the weighted mean is biased and the direction and amount of the bias can be explained by the correlation between survey variate and weight: if the correlation coefficient is positive, then the weighted mein over-estimates the population mean, on the other hand, if negative, then under-estimates. Also the magnitude of bias is getting larger when the correlation coefficient is getting greater. In addition to theoretical derivation about the weighted mean, we conduct a simulation study to show quantities of the bias and mean square errors numerically. In the simulation, nine weights having correlation coefficient with survey variate from -0.2 to 0.6 are generated and four sample sizes from 100 to 400 are considered and then biases and mean square errors are calculated in each case. As a result, in the case or 400 sample size and 0.55 correlation coefficient, the amount or squared bias of the weighted mean occupies up to 82% among mean square error, which says the weighted mean might be biased very seriously in some cases.

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