• Journal of Labour Economics
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• v.30 no.3
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• pp.103-138
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• 2007

The purpose of this study is: (1) to compare the awareness of inequality concept between Korea and other countries using the survey, (2) to identify whether several inequality measures, which have diverse concepts, are different in empirical aspect, and (3) to suggest the direction for the income distribution policy in Korea. The results of the survey has shown a surprising fact in that the majority of respondents do not agree with the basic assumptions outlined by Gini coefficient, which is the relative inequality measures that had been generally accepted in the past. These results are very similar to those of other countries. However, the major difference with other countries is that the Koreans feel that absolute income inequality-the income gap between the poor and rich, has increased more than relative income inequality, when all incomes of social members are doubled. From the result it is difficult to say that the bi-polarization index is different from Gini coefficient in statistical aspect although it has different theoretical background. The national development strategy should seek to promote "the pro-poor growth" since the change of inequality affect differently on the change of growth and inequality depending on whether the inequality change is relative or absolute.

• Honam Mathematical Journal
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• v.40 no.3
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• pp.509-519
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• 2018

In this paper, we introduce a new class of reciprocal convex set which is called as relative reciprocal convex set. We establish a necessary and sufficient condition for the minimum of the differentiable relative reciprocal convex function. This condition can be viewed as a new class of variational inequality which is called relative reciprocal variational inequality. Using the auxiliary principle technique we discuss the existence criteria for the solution of relative reciprocal variational inequality. Some special cases which are naturally included in our main results are also discussed.

• Journal of Preventive Medicine and Public Health
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• v.51 no.6
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• pp.310-319
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• 2018

Objectives: This study examined trends in inequality in cigarette smoking prevalence by income according to recent anti-smoking policies in Korea. Methods: The data used in this study were drawn from three nationally representative surveys, the Korea National Health and Nutrition Examination Survey, the Korea Community Health Survey, and the Social Survey of Statistics Korea. We calculated the age-standardized smoking prevalence, the slope index of inequality, and the relative index of inequality by income level as a socioeconomic position indicator. Results: Smoking prevalence among men decreased during the study period, but the downward trend became especially pronounced in 2015, when the tobacco price was substantially increased. Inequalities in cigarette smoking by income were evident in both genders over the study period in all three national surveys examined. Absolute inequality tended to decrease between 2014 and 2015 among men. Absolute and relative inequality by income decreased between 2008 and 2016 in women aged 30-59, except between 2014 and 2015. Conclusions: The recent anti-smoking policies in Korea resulted in a downward trend in smoking prevalence among men, but not in relative inequality, throughout the study period. Absolute inequality decreased over the study period among men aged 30-59. A more aggressive tax policy is warranted to further reduce socioeconomic inequalities in smoking in young adults in Korea.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.625-631
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• 2011

This paper presents a discrete-time output feedback consensus algorithm for Multi-Agent Systems (MAS). Under the assumption that an agent is aware of the relative state information about its neighbors, a state feedback consensus algorithm is designed based on Linear Matrix Inequality (LMI) method. In general, however, it is possible to obtain its relative output information rather than the relative state information. To reconcile this problem, an Unknown Input Observer (UIO) is employed in this paper. To this end, first it is shown that the relative state information can be estimated using the UIO and the measured relative output information. Then a certainty-equivalence type output feedback consensus algorithm is proposed by combining the LMI-based state feedback consensus algorithm with the UIO. Finally, simulation results are given to illustrate that the proposed method successfully achieves the state consensus.

• Journal of applied mathematics & informatics
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• v.39 no.5_6
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• pp.751-760
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• 2021

We study in this paper the right Rényi mean for a quantum divergence induced from the α - z Rényi relative entropy. Many properties including homogeneity, invariance under permutation, repetition and unitary congruence transformation, and determinantal inequality have been presented. Moreover, we give the identity of two right Rényi means with respect to tensor product.

• Korean Journal of Mathematics
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• v.18 no.2
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• pp.195-200
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• 2010

Let C be a closed convex set in ${\mathbb{S}}^m$ or ${\mathbb{H}}^m$. Assume that ${\Sigma}$ is an n-dimensional compact minimal submanifold outside C such that ${\Sigma}$ is orthogonal to ${\partial}C$ along ${\partial}{\Sigma}{\cap}{\partial}C$ and ${\partial}{\Sigma}$ lies on a geodesic sphere centered at a fixed point $p{\in}{\partial}{\Sigma}{\cap}{\partial}C$ and that r is the distance in ${\mathbb{S}}^m$ or ${\mathbb{H}}^m$ from p. We make use of a modified volume $M_p({\Sigma})$ of ${\Sigma}$ and obtain a sharp relative isoperimetric inequality $$\frac{1}{2}n^n{\omega}_nM_p({\Sigma})^{n-1}{\leq}Vol({\partial}{\Sigma}{\sim}{\partial}C)^n$$, where ${\omega}_n$ is the volume of a unit ball in ${\mathbb{R}}^n$ Equality holds if and only if ${\Sigma}$ is a totally geodesic half ball centered at p.

• Korean Journal of Mathematics
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• v.16 no.4
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• pp.527-535
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• 2008

Let $I{\in}C^{1,1}$ be a strongly indefinite functional defined on a Hilbert space H. We investigate the number of the critical points of I when I satisfies one pair of Torus-Sphere variational linking inequality. We show that I has at least two critical points when I satisfies one pair of Torus-Sphere variational linking inequality with $(P.S.)^*_c$ condition. We prove this result by use of the limit relative category and critical point theory on the manifold with boundary.

• Journal of Labour Economics
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• v.30 no.3
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• pp.77-102
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• 2007

This paper compares income and consumption for their relative effectiveness in measuring inequality. Although income inequality has received more attention in the literature, the permanent income hypothesis links consumption to welfare more directly than income. To the extent economic agents smooth their consumptions, consumption inequality is a better indicator for an economy's welfare inequality, and it is especially so when income volatility is high. The empirical analysis in this paper indicates that the income and consumption patterns among the Korean wage/salary worker households are quite consistent with the permanent income hypothesis. Further, it is found that consumption inequality tends to be lower than income inequality, and more importantly, that the two inequalities do not always vary in the same direction. These results call for stronger emphasis on consumption inequality in inequality literature.

• Journal of Preventive Medicine and Public Health
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• v.40 no.5
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• pp.381-387
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• 2007

Objectives: This study was conducted in order to determine how the association between socioeconomic position(SEP) and health status changes with age among Seoul residents aged 25 and over. Methods: We utilized the 2001 and 2005 Seoul Citizens Health Indicators Surveys. We used self-rated 'poor' health status as an outcome variable, and family income as an indicator of SEP. In order to characterize the differential effects of socioeconomic position on health by age, we conducted separate multivariate analyses by 10-year age groups, controlling for sociodemographic covariates. In order to assess the relative health inequality across socioeconomic groups, we estimated the Relative Index of Inequality (RII). Results: The risk of 'poor health' is significantly high in low family income groups, and this increased risk is seen at all ages. However, the magnitude of relative socioeconomic inequality in health, as measured by the odds ratio and RII, is not identical across age groups. The difference in health across income groups is small in early adulthood (ages 25-34), but increases with age until relatively late in life (ages 35-64). It then decreases among the elderly population (ages more than 65). When the RII reported in 2005 is compared to that reported in 2001, RII can be seen to have increased across all ages, with the exception of individuals aged 25-34. Conclusions: The magnitude of health inequality is the greatest during mid- to late adulthood (ages 45-64). In addition, health inequalities have worsened between 2001 and 2005 across all age groups after economic crisis.

• Korean Journal of Social Welfare
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• v.64 no.2
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• pp.55-83
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• 2012

Self-employment rate is high in Korean labor market, while the income gap within self-employed is also high. Although, there are very few studies that addressed on the income inequality of self-employed. Thus, this study has measured the earnings inequality of self-employed by generalized entropy indices and decomposed inequality factor and trend. The empirical study is based on Korea Welfare Panel Study wave 1~4. The main result from this analysis is summarized in three points. Firstly, earnings inequality of self-employed is severely high and the earnings polarization within self-employed has become more serious in Korea. Secondly, this study provides the evidence that the main factor of earnings inequality of self-employed is the status of self-employment, education level, age group, workplace scale and industry. Thirdly, the contribution of relative changes in the incomes of the status of self-employment is the largest to the inequality trend. In terms of education level, age group and industry, the increase of inequality within group(pure effect) mainly attributes to the rise of earnings inequality of self-employed and the change effect of group composition contributes to deterioration of inequality.