• 지구물리와물리탐사
• /
• 제16권4호
• /
• pp.284-292
• /
• 2013

삼각망에서 얻은 2차원 변위자료로부터 주축변형, 회전, 팽창등을 산출하는 안정된 계산순서를 제시하였으며, 이들 추산치의 오차가 삼각망의 면적간에 반비례하므로 자료망의 크기를 택함에 유의하여야함을 지적하였다. 이 순서를, 2011년 토호쿠지진에 의해 발생한 한반도지역의 변위의 GPS관측자료에 적용하여 안정된 추산치들을 얻었다.

• Communications for Statistical Applications and Methods
• /
• 제6권1호
• /
• pp.275-283
• /
• 1999

In order to estimate a parameter $(\alpha,\beta^r), r\epsilonN$, in a distribution belonging to a location-scale family we usually use best invariant estimator (BIE) and best unbiased estimator (BUE). But in some conditions Ryu (1996) showed that BIE is better than BUE. In this paper we calculate risks of BIE and BUE in a normal and an exponential distribution respectively and calculate a percentage risk improvement exponential distribution respectively and calculate a percentage risk improvement (PRI). We find the sample size n which make no significant differences between BIE and BUE in a normal distribution. And we show that BIE is always significantly better than BUE in an exponential distribution. Also simulation in a normal distribution is given to convince us of our result.

• Journal of Electrical Engineering and Technology
• /
• 제13권2호
• /
• pp.559-567
• /
• 2018

In this paper, we propose a new load forecasting method for smart air conditioning (A/C) based on the modified thermodynamics of indoor temperature and the unbiased finite memory estimator (UFME). Based on modified first-order thermodynamics, the dynamic behavior of indoor temperature can be described by the time-domain state-space model, and an accurate estimate of indoor temperature can be achieved by the proposed UFME. In addition, a reliable A/C load forecast can be obtained using the proposed method. Our study involves the experimental validation of the proposed A/C load forecasting method and communication construction between DR server and HEMS in a test bed. Through experimental data sets, the effectiveness of the proposed estimation method is validated.

• International Journal of Reliability and Applications
• /
• 제14권1호
• /
• pp.27-39
• /
• 2013

In this article, a new model based on the Rayleigh distribution is introduced. This model is useful and practical in physics, reliability, and life testing. The statistical and reliability properties of this model are presented, including moments, the hazard rate, the reversed hazard rate, and mean residual life functions, among others. In addition, it is shown that the distributions of the new model are ordered regarding the strongest likelihood ratio ordering. Four estimating methods, namely, method of moment, maximum likelihood method, Bayes estimation, and uniformly minimum variance unbiased, are used to estimate the parameters of this model. Simulation is used to calculate the estimates and to study their properties. Finally, the appropriateness of this model for real data sets is shown by using the chi-square goodness of fit test and the Kolmogorov-Smirnov statistic.

• 대한수학회지
• /
• 제61권3호
• /
• pp.427-444
• /
• 2024

The matrix completion problem is to predict missing entries of a data matrix using the low-rank approximation of the observed entries. Typical approaches to matrix completion problem often rely on thresholding the singular values of the data matrix. However, these approaches have some limitations. In particular, a discontinuity is present near the thresholding value, and the thresholding value must be manually selected. To overcome these difficulties, we propose a shrinkage and thresholding function that smoothly thresholds the singular values to obtain more accurate and robust estimation of the data matrix. Furthermore, the proposed function is differentiable so that the thresholding values can be adaptively calculated during the iterations using Stein unbiased risk estimate. The experimental results demonstrate that the proposed algorithm yields a more accurate estimation with a faster execution than other matrix completion algorithms in image inpainting problems.

• Journal of the Korean Statistical Society
• /
• 제22권2호
• /
• pp.209-217
• /
• 1993

The multicollinearity problem in a multiple linear regression model may present deleterious effects on predictions. Thus, its is desirable to consider the optimal fractions with respect to the unbiased estimate of the mean squares errors of the predicted values. Interstingly, the optimal fractions can be also illuminated by the Bayesian inerpretation of the general James-Stein estimators.

• Journal of the Korean Data and Information Science Society
• /
• 제13권1호
• /
• pp.147-156
• /
• 2002

In this paper, we study the properties of the modified winsorized mean to estimate the mean of a two-truncation parameter population. Under some mild conditions, the estimator is found to be strongly consistent and asymptotically unbiased even though the sample is doubly type II censored.

• Journal of the Korean Data and Information Science Society
• /
• 제18권4호
• /
• pp.1179-1189
• /
• 2007

In this paper, we estimate the proportion of individuals having health insurance in a given year for several small domains cross-classified by age, sex and other demographic characteristics using the data provided by the National Center for Health Statistics(NCHS). We employ Bayesian as well as frequentist methodology to obtain small domain estimates and the associated measures of precision. One of the new features of our study is that we utilize the survey weights along with the model to derive the small domain estimates.

• Journal of the Korean Statistical Society
• /
• 제12권2호
• /
• pp.69-80
• /
• 1983

The purpose of this paper is to obtain representation of the mathematical special functions and the numerical values of the mean square errors for the quasi-ranges in random small smaples ($n \leq 30$) from the Weibull distribution with a shape and a scale parameters, and to estimate the scale parameter by use of unbiased estimator based on the quasi-range. It will be shown that the jackknife estimator of the range is worse than the range of random samples from the given distribution in the sense of the mean square error.

• 천문학회보
• /
• 제36권2호
• /
• pp.144.1-144.1
• /
• 2011

We explore the metallicity distribution of the Galactic halo based on the SDSS ugriz photometry. We use empirically calibrated sets of stellar isochrones to determine distances and metallicities of individual main-sequence stars in the halo. At heliocentric distances greater than 5 kpc, we find that the in situ photometric metallicity distribution reveals chemically divided dual halo components, which supports arguments from earlier studies based on the medium resolution spectroscopy. Our finding provides an unbiased estimate of relative fractions of each of these stellar components in the Galactic halo.