• Communications for Statistical Applications and Methods
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• v.15 no.2
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• pp.161-171
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• 2008

This study discusses Johnson's $S_U$-normal distribution capturing a wide range of non-normality in various regression models. We provide the likelihood inference using Johnson's $S_U$-normal distribution, and propose a likelihood ratio (LR) test for normality. We also apply the $S_U$-normal distribution to the binary and censored regression models. Monte Carlo simulations are used to show that the LR test using the $S_U$-normal distribution can be served as a model specification test for normal error distribution, and that the $S_U$-normal maximum likelihood (ML) estimators tend to yield more reliable marginal effect estimates in the binary and censored model when the error distributions are non-normal.

• Communications for Statistical Applications and Methods
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• v.19 no.3
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• pp.345-358
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• 2012

In a parametric sample selection model, the distribution assumption is critical to obtain consistent estimates. Conventionally, the normality assumption has been adopted for both error terms in selection and main equations of the model. The normality assumption, however, may excessively restrict the true underlying distribution of the model. This study introduces the $S_U$-normal distribution into the error distribution of a sample selection model. The $S_U$-normal distribution can accommodate a wide range of skewness and kurtosis compared to the normal distribution. It also includes the normal distribution as a limiting distribution. Moreover, the $S_U$-normal distribution can be easily extended to multivariate dimensions. We provide the log-likelihood function and expected value formula based on a bivariate $S_U$-normal distribution in a sample selection model. The results of simulations indicate the $S_U$-normal model outperforms the normal model for the consistency of estimators. As an empirical application, we provide the sample selection model for car ownership and a car expense relationship.

• KDI Journal of Economic Policy
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• v.32 no.3
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• pp.71-99
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• 2010

The concept of CoVaR introduced by Adrian and Brunnermeier (2009) is a useful tool to measure the risk spillover effect. It can capture the risk contribution of each institution to overall systemic risk. While Adrian and Brunnermeier rely on the quantile regression method in the estimation of CoVaR, we propose a new estimation method using parametric distribution functions such as bivariate normal and $S_U$-normal distribution functions. Based on our estimates of CoVaR for Korean banking industry, we investigate the practical usefulness of CoVaR for a systemic risk measure, and compare the estimation performance of each model. Empirical results show that bank makes a positive contribution to system risk. We also find that quantile regression and normal distribution models tend to considerably underestimate the CoVaR (in absolute value) compared to $S_U$-normal distribution model, and this underestimation becomes serious when the crisis in a financial system is assumed.

• International Journal of Reliability and Applications
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• v.10 no.2
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• pp.81-88
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• 2009

A non-parametric procedure is presented for testing exponentially against used better than aged in convex ordering class (UBAC) of life distributions based on u-test. Convergence of the proposed statistic to the normal distribution is proved. Selected critical values are tabulated for sample sizes 5(5)40. The Pitman asymptotic relative efficiency of my proposed test to tests of other classes is studied. An example of 40 patients suffering from blood cancer disease demonstrates practical application of the proposed test.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.331-333
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• 2003

This paper describes the effect of the interconnected wind turbine generators on fault current level of distribution networks. Distributed generator(DG) interconnected with grid can supply the power into a power network not only the normal conditions, but also the fault conditions of distribution network. If the fault happened in the distribution power line with DG, the fault current level measured in a relaying point might be higher than that of distribution network without wind turbine generator due to the contribution of wind farm. Consequently, it may destroy the conventional protective devices applied in the distribution network with DG. Simulation results shows that the current level of fault happened in the power line with DG depends on the power output of DG.

• Journal of Distribution Science
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• v.20 no.9
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• pp.83-95
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• 2022

Purpose: This study aims to explore an ability to time market-wide investor sentiment of mutual fund managers in an emerging market. Research design, data, and methodology: Based on data of Thai mutual fund market over the period of 2000-2019, our sample includes 283 equity funds, consisting of 204 bank-related funds and 79 nonbank-related funds. We perform our regression analyses at the aggregate and portfolio levels. Results: Under the non-normal distribution of return, we find different behaviors between the best- and worst-performing funds in an ability to time market-wide investor sentiment in Thailand, which is dissimilar to the findings in the U.S. Bottom fund managers act as sentiment hedgers, who decrease (increase) an exposure of investment portfolios when the investor sentiment is high (low). Oppositely, top fund managers are likely to chase investor sentiment. Conclusion: We find that only the worst-performing fund managers, especially for bank-related funds are able to time the market-wide investor sentiment. An advantage of gaining information from their bank's clients is a key success. A competition in the mutual fund industry, an ability to predict fundamentals, and financial literacy are possible reasons to explain the main findings found in this study.

• The Korean Journal of Nuclear Medicine
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• v.21 no.2
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• pp.133-141
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• 1987

To evaluate the values of the thyroid autoantibody measured by radioimmunoassay (RIA) and compare it with hemagglutination method (HA) in the normal and the thyroid disease, data were obtained from total 618 persons; 236 healthy persons, 217 patients with Graves' disease (including 113 patients with undertreated Graves' disease), 100 Hashimoto's disease, 31 thyroid nodule, and 34 simple goiter. RSR kit made in England was used and could be detected to at least 3 U/ml. The positive rates of normal group were antimicrosomal antibody (AMA) 31.8%, antithyroglobulin antibody (ATA) 44.5% by RIA and there was no considerable change in sex and age distribution. In Graves' disease, the positive rates of AMA and ATA were 90.4, 76.9% by RIA, 85, 39% by HA. In Hashimoto's disease, 94,91 % by RIA, and 87,48% by HA, respectively. The autoantibody titer by RIA in thyroid autoimmune disease as well as in normal group was more senisitive than that by HA, especially in ATA. There were linear relationships between the titer of RIA and that of HA in AMA of Graves' disease and AMA and ATA of Hashimoto's disease. There was no relationship among thyroid autoantibody, free $T_4$ index, TBII, and TSH. The titers of AMA and ATA were found to decrease in patients with Graves' disease during the course of antithyroid drug therapy. Of the 236 normal subjects, thirty-seven (15.7%) had concentrations of above 7.5 U/ml in AMA, forty. four (18.6%) above 9 U/ml in ATA. These values were considered as the upper limit for the normal range. In Graves' disease, 82.7, 53.8% were above 7.5, 9 U/ml, respectively; In Hashimoto's disease, 82, 79% were positive. We conclude that RIA was more sensitve than HA in measuring the thyoird autoantibody, but we will study further more for determining the normal range and its interpretation.

• Journal of Korean Society for Atmospheric Environment
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• v.8 no.4
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• pp.269-276
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• 1992

Typical lebvels of heavy metal exposure for humans may be attributed to four components in the environment ; food, inhaled air, various types of dust, and drinking water. To assess the health risk of lead, it is necessary to estimate the blood lead levels in the populations of concern under various air lead concentrations. The blood lead levels of the population in Seoul and Yeoju are estimated by Biokinetic model for the risk assessment in this study. The differences in blood lead levels between areas of different land use are not dominant but some differences show among different age groups and sex. Blood lead levels of the population show log normal distribution. The geometric standard deviation values of blood lead levels are in the range of 1.25 ~ 1.39, it is somewhat smaller than the values in the general U.S pollution which are determined to be from 1.31 to 1.41 by the U.S. EPA.

• Journal of the Korean Statistical Society
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• v.32 no.2
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• pp.175-191
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• 2003

An empirical Bayesian approach is discussed for estimation of characteristics from the two-way balanced rotation sampling design which includes U.S. Current Population Survey and Canadian Labor Force Survey as special cases. An empirical Bayesian estimator is derived for monthly effect under presence of two types of biases and correlations It is shown that the marginal distribution of observation provides more general correlation structure than that frequentist has assumed. Consistent estimators are derived for hyper-parameters in Normal priors.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.4
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• pp.398-404
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• 1993

In order to examine the anticarcinogenic effects of garlic juice on the hamster buccal pouch carcinogenesis induced by 9, 10-dimethyl-1, 2-benzanthracene (DMBA) totally 135 hamster.0.5% DMBA in mineral oil were painted onto the hamster buccal pouch three times a week on 50th, 70th and 90th day, while normal saline, 1% and 3% garlic juice were forced to oral tube feeding. Tumor cell induction could be seen on 50th experimental day, presumed to early carcinogenic inductive stage. And the tumor cells proliferated rapidly thereafter, so 70th and 90th experimental day were chosen for the comparison of anticarcinogenic effect of garlic juice. The every specimens were fixed in 10% buffered formalin for routine histopathological observation and also fixed in Carnoy's solution for the BrdU immunohistochemital detection of S-stage tumor cell distribution during the carcinogenesis. There showed more or less increased anticarcinogenic effect of garlic juice against DMBA induced hamster buccal pouch carcinoma, increased comparing to the control group showing invasive tumor growth after all histopathologically, BrdU immunoreactivity on normal pouch mucosa epithelium, representing the mitotic status, more decreased in the garlic juice feeding group than the control group. Meanwhile the neoplastic epithelium of all experimental groups showed much increased BrdU immunostaining irregularly.