• Title/Summary/Keyword: Sample case

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An Improved Method for Constructing Confidence Interval of Median : Small Sample Case

  • Park, Sang-Gue;Choi, Ji-Yun
    • Journal of the Korean Data and Information Science Society
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    • v.15 no.4
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    • pp.973-980
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    • 2004
  • Phase I clinical trials are often pharmacologically oriented and usually attempt to find the best dose of drug to employ. However, other purposes like determination of sizes and types of side effects and toxicity and organ system involved are equally important. Estimation of treatment effects or side effects is usually ignored since it is usually based on too small sample, even though Phase II clinical trials would be designed based on the Phase I studies. Statistical methods for constructing the approximate confidence interval for population median in case of small sample are considered and an improved method is proposed. The proposed estimator is compared with current methods through simulation studies.

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Current Density Equations Representing the Transition between the Injection- and Bulk-limited Currents for Organic Semiconductors

  • Lee, Sang-Gun;Hattori, Reiji
    • Journal of Information Display
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    • v.10 no.4
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    • pp.143-148
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    • 2009
  • The theoretical current density equations for organic semiconductors was derived according to the internal carrier emission equation based on the diffusion model at the Schottky barrier contact and the mobility equation based on the field dependence model, the so-called "Poole-Frenkel mobility model." The electric field becomes constant because of the absence of a space charge effect in the case of a higher injection barrier height and a lower sample thickness, but there is distribution in the electric field because of the space charge effect in the case of a lower injection barrier height and a higher sample thickness. The transition between the injection- and bulk-limited currents was presented according to the Schottky barrier height and the sample thickness change.

표준시료를 이용한 토양중 중금속 분석방법 비교

  • Yun Jeong-Gi;Kim Tae-Seung;Kim Dong-Ho;Jeon Seong-Hwan;Jeong Il-Rok;Kim Hyeok
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2005.04a
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    • pp.242-246
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    • 2005
  • The heavy metal analysis (Cd, Pb, Cu, Cr, Zn, Ni) with various extraction methods was performed using the certified sample and real soil sample. In case of the certified samples, $10.5{\sim}118%$ of recovery was showed with various ranges depend on the metal kinds and extraction methods. Also, the alkali-digestion method was showed the proper results by applying in hexavalent chromium. In case of real sample, compared to amounts of heavy metals extracted using 0.1N-HCl, those extracted using acid digestion are higher by $3{\sim}24$ times in Cu, $1.1{\sim}1.5$ times in Cd, $2{\sim}23$ times in Pb, $3{\sim}104$ times in Zn, $12{\sim}101$ times in Ni, $30{\sim}202$ times in Cr. There is no considerable difference between four acid digestion methods.

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A Study on the physical characteristics of foaming glass by recycling waste glass (재생발포유리의 물리적 특성에 관한 연구)

  • Kim Hyung-Ju;Chang Pil-Kyu;Choi Chang-Ha;Lee Soo-Wohn;Cho Hae-Yong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.6 no.6
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    • pp.473-477
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    • 2005
  • In the study of foaming a general waste glass, sample 1 to 5 were made in a various foaming conditions, measurements of pH, density, compressive strength, thermal conductivity, and the sound absorption rate were carried out. Sample I showed the most small pore, and sample 5 showed pores of 3 times larger than that of sample 1. In terms of pore size, Sample 5 was foamed mostly well, but except lower density compressive strength, efficiency of sound absorption, testing in sound room were obtained below the minimum values is lower. In the case of Sample 1 it showed $0.58g/cm^3$, but the final target value was $0.8g/cm^3$. In the case of compressive strength it showed $22kg/cm^3$, which is above value of the final target. The efficiency of sound absorption of Sample 1 showed NRC 0.68, which is close to the final target of NRC 0.7.

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Estimation in a Two-Sample Proportional Odds Model

  • Kim, Ju-Sung;Seo, Min-Ja
    • Journal of the Korean Data and Information Science Society
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    • v.16 no.2
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    • pp.327-334
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    • 2005
  • In this paper we propose a new estimator of relative odds ratio in the two-sample case of proportional odds model. Also, we show that the estimator is consistent and asymptotically normal. The efficiency of the proposed is assessed through a simulation study.

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On the Autocovariance Function of INAR(1) Process with a Negative Binomial or a Poisson marginal

  • Park, You-Sung;Kim, Heeyoung
    • Journal of the Korean Statistical Society
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    • v.29 no.3
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    • pp.269-284
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    • 2000
  • We show asymptotic normality of the sample mean and sample autocovariances function generated from first-order integer valued autoregressive process(INAR(1)) with a negative binomial or a Poisson marginal. It is shown that a Poisson INAR(1) process is a special case of a negative binomial INAR(1) process.

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Some nonparametric test procedure for the multi-sample case

  • Park, Hyo-Il;Kim, Ju-Sung
    • Journal of the Korean Data and Information Science Society
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    • v.20 no.1
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    • pp.237-250
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    • 2009
  • We consider a nonparametric test procedure for the multi-sample problem with grouped data. We construct the test statistics based on the scores obtained from the likelihood ratio principle and derive the limiting distribution under the null hypothesis. Also we illustrate our procedure with an example and obtain the asymptotic properties under the Pitman translation alternatives. Also we discuss some concluding remarks. Finally we derive the covariance between components in the Appendix.

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Minimum risk point estimation of two-stage procedure for mean

  • Choi, Ki-Heon
    • Journal of the Korean Data and Information Science Society
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    • v.20 no.5
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    • pp.887-894
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    • 2009
  • The two-stage minimum risk point estimation of mean, the probability of success in a sequence of Bernoulli trials, is considered for the case where loss is taken to be symmetrized relative squared error of estimation, plus a fixed cost per observation. First order asymptotic expansions are obtained for large sample properties of two-stage procedure. Monte Carlo simulation is carried out to obtain the expected sample size that minimizes the risk and to examine its finite sample behavior.

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On the Estimation in Regression Models with Multiplicative Errors

  • Park, Cheol-Yong
    • Journal of the Korean Data and Information Science Society
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    • v.10 no.1
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    • pp.193-198
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    • 1999
  • The estimation of parameters in regression models with multiplicative errors is usually based on the gamma or log-normal likelihoods. Under reciprocal misspecification, we compare the small sample efficiencies of two sets of estimators via a Monte Carlo study. We further consider the case where the errors are a random sample from a Weibull distribution. We compute the asymptotic relative efficiency of quasi-likelihood estimators on the original scale to least squares estimators on the log-transformed scale and perform a Monte Carlo study to compare the small sample performances of quasi-likelihood and least squares estimators.

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