• The Korean Journal of Applied Statistics
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• v.13 no.2
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• pp.343-352
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• 2000

In this study. the author proposes a nonhierarchical clustering method. called the "Double K-Means Clustering", which performs clustering of multivariate observations with the following algorithm: Step I: Carry out the ordinary K-means clmitering and obtain k temporary clusters with sizes $n_1$,... , $n_k$, centroids $c_$1,..., $c_k$ and pooled covariance matrix S. $\bullet$ Step II-I: Allocate the observation x, to the cluster F if it satisfies ..... where N is the total number of observations, for -i = 1, . ,N. $\bullet$ Step II-2: Update cluster sizes $n_1$,... , $n_k$, centroids $c_$1,..., $c_k$ and pooled covariance matrix S. $\bullet$ Step II-3: Repeat Steps II-I and II-2 until the change becomes negligible. The double K-means clustering is nearly "optimal" under the mixture of k multivariate normal distributions with the common covariance matrix. Also, it is nearly affine invariant, with the data-analytic implication that variable standardizations are not that required. The method is numerically demonstrated on Fisher's iris data.

• Korean Journal of Clinical Pharmacy
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• v.25 no.3
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• pp.131-137
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• 2015

Background: The protective effect of metformin against breast cancer is inconclusive. Objective: To evaluate the effect of metformin on breast cancer risk and mortality in patients with type 2 diabetes. Method: A comprehensive literature search was performed for pertinent articles published prior to June 30, 2014, using PubMed and EMBASE. Study heterogeneity was estimated with $I^2$ statistic. The data from the included studies were pooled and weighted by random-effects model. The quality of each included study was assessed on the basis of the 9-star Newcastle-Ottawa Scale and publication bias was evaluated by visual inspection of a funnel plot. Results: Ten studies were included in the meta-analysis of the association of metformin and breast cancer risk. By synthesizing the data from the studies, the pooled odds ratio (OR) was 0.72 (95% CI: 0.59, 0.87) (p = 0.0005). Three cohort studies were included for meta-analysis of the association between metformin and breast cancer-related mortality. Metformin was associated with a significant decrease in mortality (Risk ratio: 0.68; 95% CI: 0.51, 0.90, p = 0.007). Conclusion: The present meta-analysis suggests that metformin appears to be associated with a lower risk of breast cancer incidence and mortality in patients with type 2 diabetes.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.12
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• pp.1696-1700
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• 2001

An experiment was conducted to examine the effect of different feeding levels of concentrate (85, 100 and 115%) and age (15, 18 and 24 month) on fatty acid synthetase (FAS) activities in the 4 locations of adipose tissues (intermuscular, ITER; intramuscular, ITRA; kidney, KIDN and subcutaneous, SUBC) of 36 Korean native cattle (Hanwoo) steers. Steers of 100% feeding group were fed the amount of concentrate to meet the daily nutrient requirements, and the steers of second and third groups were fed concentrates at the levels of 85% and 115% of that of control group, respectively, up to 18 month of age. Thereafter, the steers were fed ad libitum up to 24 month of age. Feeding level of concentrates tended to affect the FAS activity of various adipose tissues in Hanwoo steers of each age. The FAS activity of ITER adipose tissue had the decreasing trend as the age of steers advanced while those of ITRA and SUBC adipose tissues had the slightly increasing tendency with age. The FAS activity based on the pooled data increased with the feeding level of concentrates (115%) in which the activities from all 4 adipose depots were higher than those with the lowest (85%) feeding level. Similar trend was observed from the pooled data of feeding level of concentrates by age of steers in which the FAS activities for all 3 ages were increased with feeding levels of concentrates. But the response in the FAS activity to the feeding level varied with age.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.4
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• pp.317-328
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• 2021

This study aims to determine the factors that affect dividends initiation by initial public offering firms in Malaysia. The ownership structure is examined from a corporate governance theoretical perspective in order to evaluate the impacts of managerial, institutional, and family ownership on the dividend's initiation decision of IPO firms. This study employs a quantitative pooled cross-section of 372 Malaysian IPO companies active during the period of 2002-2013. The number of firms that went public each year varies, thus the pooled cross-section data takes place in this case rather than the panel data. The logistic model was employed to test the proposed hypotheses. The results revealed that the presence of institutional investors in the ownership structure make it more likely for IPO firms to initiate dividends. On the contrary, the presence of a family ownership structure in IPO companies as the controlling shareholder makes these companies less probable to initiate dividends. Managerial ownership was found to have no effect on the decision of initiating dividends by IPO firms. The findings of this study suggest that the existence of institutional and family ownerships are agency cost mitigators, as these ownership types could prompt IPOs firms to initiate dividends to overcome the agency conflicts.

• International Journal of Industrial Entomology and Biomaterials
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• v.41 no.2
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• pp.56-62
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• 2020

Mulberry (Morus spp. family: Moraceae) has prime importance in the sericulture industry, and its foliage is the only natural feed of the silkworm Bombyx mori L. Traditional classification methods using morphological traits were largely unsuccessful in assessing the diversity and relationships among different mulberry species because of environmental influences on the traits of interest. For these reasons, it is difficult to differentiate between the varieties and cultivars of Morus spp. In the present study, inter-simple sequence repeat (ISSR) markers were used to investigate the genetic diversity of 48 mulberry samples genotyped using nine ISSR primers. The ISSR markers exhibited polymorphisms (53.2%) among mulberry genotypes. Furthermore, similarity coefficient estimated for these ISSR markers was found to vary between 0.67 and 0.99 for the combined pooled data. The phenogram drawn using the UPGMA cluster method based on combined pooled data of the ISSR markers divided the 48 mulberry genotypes into seven major groups. No genetic association was found in the collection area, and there was a mixed pattern between the mulberry lines. The hybridization between different mulberry species is highly likely to be homogenized due to natural hybridization.

• Korean Journal of Social Welfare
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• v.59 no.1
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• pp.5-25
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• 2007

The purpose of this study is to explore factors influencing the poverty of the elderly in Korea. In spite the fact that poverty of the elderly is more serious than any other demographic group, this important issue is rarely studied. Using the 7-year accumulated data from the KLIPS(Korean Labor and Income Study), I combined the work history of the elders, their demographic characteristics and residence to estimate pooled data analysis of the elderly after reaching age 55 and who are also only living by themselves(only the elders). The results of this study are as followed: first of all, age, education, marital status, wealth, residence and work history are shown to be significant predictors for the poverty of elderly. Second, the results show that factors influencing the poverty is different depending on the elder's (demographic) characteristics. For example, age and marital status is a more important predictor in female than in male, and wealth and health status is a more important predictor in elders who do not have a spouse than in elders who do. Such results suggest that the policy of the poverty of the elderly which is only focused on elder's characteristic is limited. Therefore we can suggest that a policy which workable people can earn decent income and saving wealth for their elderly in job is needed. Especially, policies on the 'Working Poor' and reconstruct the current public pension system is very much needed.

• Journal of the Korean Data and Information Science Society
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• v.25 no.5
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• pp.971-986
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• 2014

When thousands of hypotheses are tested simultaneously, the probability of rejecting any true hypotheses increases, and large multiplicity problems are generated. To solve these problems, researchers have proposed different approaches to multiple testing methods, considering family-wise error rate (FWER), false discovery rate (FDR) or false nondiscovery rate (FNR) as a type I error and some test statistics. In this article, we discuss Bonferroni (1960), Holm (1979), Benjamini and Hochberg (1995) and Benjamini and Yekutieli (2001) procedures based on T statistics, modified T statistics or local-pooled-error (LPE) statistics. We also consider Sun and Cai (2007) procedure based on Z statistics. These procedures are compared in the simulation and applied to Arabidopsis microarray gene expression data to identify differentially expressed genes.

• Journal of Environmental Health Sciences
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• v.33 no.4
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• pp.264-275
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• 2007

The objective of this study was to offer basic and scientific data for decision-making of policy for improvement and management of radon, natural radiation gas, in Korea and to form the foundation of radon related international cooperation. Therefore, this study collected and re-analysed the articles on exposure of radon in various indoor environment in journals related environment in Korea since 1980 and estimated the annual exposure dose and effective dose by exposure of radon received by inhabitants in them. The highest pooled average radon concentration of $50.17{\pm}4.08\;Bq/m^3$ (95% CI : $42.17{\sim}58.17\;Bq/m^3$) was found in dwelling house among various indoor environment. All of pooled average radon concentration estimated in this study showed lower than the guideline concentration ($148\;Bq/m^3)$ of US EPA and the Korean Ministry of Environment. The annual effective dose received by inhabitants in various indoor environment was estimated 1.071 mSv/yr. That is equal to annual effective dose (1.0 mSv/yr) by exposure of radon estimated by UNSCEAR.

• Health Policy and Management
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• v.24 no.1
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• pp.47-55
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• 2014

Background: Korea is considered to have an integrative health system where both western medicine and Korean (traditional) medicine are officially recognized and provided. Although Korean medicine has been covered by National Health Insurance over 20 years, equity in the utilization of Korean medical care has rarely been examined. Methods: We examined medical care utilization and expenditure of outpatient Korean medicine using panel fixed effects model to remove selection bias. Then we compared it with pooled ordinary least square (OLS) model. This study used Korea Health Panel data, which provides accurate information on out-of-pocket health care payment, including non-covered medical services. Results: Principal findings indicate that the frequency of the utilization of Korean medicine is related with unobservable individual choices different from western medicine, so the panel fixed effect model is appropriate. But pooled OLS model is better fitted for the expenditure of Korean medicine, after controlling for western medical care expenditure. After adjusting for the selection bias, socioeconomic status (income, education) was significantly associated with the expenditure of Korean medicine, but not with the frequency of the utilization of Korean medicine. Conclusion: This study shows that expenditure of Korean medicine utilization is inequitable across socioeconomic groups, which implies that health insurance coverage of Korean medicine is not sufficient.

• Agribusiness and Information Management
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• v.8 no.2
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• pp.1-8
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• 2016

The present study has aimed at analyzing the technical and scale efficiencies of credit utilization by the farmer-borrowers in Chittoor district of Andhra Pradesh, India. DEA approach was followed to analyze the credit utilization efficiency and to analyze the factors influencing the credit utilization efficiency, log-linear regression analysis was attempted. DEA analysis revealed that, the number of farmers operating at CRS are more in number in marginal farms (40%) followed by other (35%) and small (17.5%) farms. Regarding the number of farmers operating at VRS, small farmers dominate the scenario with 72.5 per cent followed by other (67.5%) and marginal (42.5%) farmers. With reference to scale efficiency, marginal farmers are in majority (52.5%) followed by other (47.5%) and small (25%) farmers. At the pooled level, 26.7 per cent of the farmers are being operated at CRS, 63 per cent at VRS and 32.5 per cent of the farmers are either performed at the optimum scale or were close to the optimum scale (farms having scale efficiency values equal to or more than 0.90). Nearly 58, 15 and 28 percents of the farmers in the marginal farms category were found operating in the region of increasing, decreasing and constant returns respectively. Compared to marginal farmers category, there are less number of farmers operating at CRS both in small farmers category (15%) and other farmers category (22.5%). At the pooled level, only 5 per cent of the farmers are operating at DRS, majority of the farmers (73%) are operating at IRS and only 22 per cent of the farmers are operating at CRS indicating efficient utilization of credit. The log-linear regression model fitted to analyze the major determinants of credit utilization (technical) efficiency of farmer-borrowers revealed that, the three variables viz., cost of cultivation and family expenditure (both negatively influencing at 1% significant level) and family income (positively influencing at 1% significant level) are the major determinants of credit utilization efficiency across all the selected farmers categories and at pooled level. The analysis further indicate that, escalation in the cost of cultivation of crop enterprises in the region, rise in family expenditure and prior indebtedness of the farmers are showing adverse influence on the credit utilization efficiency of the farmer-borrowers.