• Journal of Preventive Medicine and Public Health
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• v.47 no.2
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• pp.104-112
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• 2014

Objectives: To date, studies have not comprehensively demonstrated the relationship between stroke incidence and socioeconomic status. This study investigated stroke incidence by household income level in conjunction with age, sex, and stroke subtype in Korea. Methods: Contributions by the head of household were used as the basis for income levels. Household income levels for 21 766 036 people were classified into 6 groups. The stroke incidences were calculated by household income level, both overall within income categories and further by age group, sex, and stroke subtype. To present the inequalities among the six ranked groups in a single value, the slope index of inequality and relative index of inequality were calculated. Results: In 2005, 57 690 people were first-time stroke patients. The incidences of total stroke for males and females increased as the income level decreased. The incidences of stroke increased as the income level decreased in those 74 years old and under, whereas there was no difference by income levels in those 75 and over. Intracerebral hemorrhage for the males represented the highest inequality among stroke subtypes. Incidences of subarachnoid hemorrhage did not differ by income levels. Conclusions: The incidence of stroke increases as the income level decreases, but it differs according to sex, age, and stroke subtype. The difference in the relative incidence is large for male intracerebral hemorrhage, whereas the difference in the absolute incidence is large for male ischemic stroke.

• Journal of Preventive Medicine and Public Health
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• v.40 no.6
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• pp.475-486
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• 2007

Objectives : Socioeconomic position (SEP) refers to the socioeconomic factors that influence which position an individual or group of people will hold within the structure of a society. In this study, we provide a comprehensive review of various indicators of SEP, including education level, occupation-based SEP, income and wealth, area SEP, life-course SEP, and SEP indicators for women, elderly and youth. Methods and results : This report provides a brief theoretical background and discusses the measurement, interpretation issues, advantages and limitations associated with the use of each SEP indicator. We also describe some problems that arise when selecting SEP indicators and highlight the indicators that appear to be appropriate for health inequality research. Some practical information for use in health inequality research in South Korea is also presented. Conclusions : Investigation into the associations between various SEP indicators and health outcomes can provide a more complete understanding of mechanisms between SEP and health. The relationship between specific SEP indicators and specific health outcomes can vary by country due to the differences in the historical, socioeconomic, and cultural contexts of the SEP indicators.

• Annals of Rehabilitation Medicine
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• v.42 no.6
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• pp.863-871
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• 2018

Objective To evaluate the association between progression of curvature of scoliosis, and correction for functional component in patients with juvenile idiopathic scoliosis (JIS). Methods We retrospectively reviewed medical data of patients prescribed custom molded foot orthosis (FO) to correct inequality of RCSPA (resting calcaneal stance position angle), and chose 52 patients (26 females, 26 males) with Cobb angle ${\geq}10^{\circ}$ in radiology and uneven pelvic level at iliac crest by different RCSPA (${\geq}3^{\circ}$) as a factor of functional scoliosis. They had different hump angle ${\geq}5^{\circ}$ in forward bending test, for idiopathic scoliosis component. Their mean age and mean period of wearing FO were $79.5{\pm}10.6months$ and $18.6{\pm}0.70months$. Results Cobb angle was reduced from $22.03^{\circ}{\pm}4.39^{\circ}$ initially to $18.86^{\circ}{\pm}7.53^{\circ}$ after wearing FO. Pelvis height difference and RCSPA difference, were reduced from $1.07{\pm}0.25cm$ initially to $0.60{\pm}0.36$, and from $4.25^{\circ}{\pm}0.71^{\circ}$ initially to $1.71^{\circ}{\pm}0.75^{\circ}$ (p<0.01). Cobb angle improved most in 9 months. However, there was no significant improvement for those with more than $25^{\circ}$ of Cobb angle initially. Mean Cobb angle improved in all age groups, but patients less than 6 years had clinically significant improvement of more than $5^{\circ}$. Conclusion JIS can have functional components, which should be identified and managed. Foot orthosis is useful in correcting functional factors, in the case of pelvic inequality caused by different RCSPA, for patients with juvenile idiopathic scoliosis.

• Journal of Preventive Medicine and Public Health
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• v.55 no.4
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• pp.389-397
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• 2022

Objectives: This study examined the effect of out-of-pocket (OOP) payment reduction on the potential utilization of low-value magnetic resonance imaging (MRI) across income groups. Methods: We conducted an experimental vignette survey using a proportional quota-based sample of individuals in Korea (n=1229). In two hypothetical vignettes, participants were asked whether they would be willing to use MRI if they had uncomplicated headache and non-specific low back pain, each before and after OOP payment reduction. To account for the possible role of physician inducement, half of the participants were initially presented with vignettes that included a physician recommendation for low-value care. The predicted probability, slope index of inequality (SII), and relative index of inequality (RII) were calculated using logistic regression. Results: Before OOP payment reduction, the lowest income quintile was least likely to use low-value MRI regardless of physician inducement (36.7-49.6% for low back pain; 30.5-39.3% for headache). After OOP payment reduction, almost all individuals in each income quintile were willing to use low-value MRI (89.8-98.0% for low back pain; 78.1-90.3% for headache). Absolute and relative inequalities concerning potential low-value MRI utilization decreased after OOP payments were reduced, even without physician inducement (SII: from 8.15 to 5.37%, RII: from 1.20 to 1.06 for low back pain; SII: from 6.99 to 0.83%, RII: from 1.20 to 1.01 for headache). Conclusions: OOP payment reduction for MRI has the potential to increase low-value care utilization among all income groups while decreasing inequality in low-value care utilization.

• Journal of Ocean Engineering and Technology
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• v.26 no.3
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• pp.20-25
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• 2012

In this paper, the authors propose a new approach to the control problem of marine vessels that are moored or controlled by actuators. The vessel control system is basically based on Dynamic Positioning System (DPS) technology. The main object of this paper is to obtain a more useful control design method for DPS. In this problem, the control allocation is a complication. For this problem, many results have been given and verified by other researchers using a two-step process, with the controller and control allocation design processes carried out individually. In this paper, the authors provide a more sophisticated design solution for this issue. The authors propose a new design method in which the controller design and control allocation problems are considered and solved simultaneously. In other words, the system stability, control performance, and allocation problem are unified by an LMI (linear matrix inequality) based on control theory. The usefulness of the proposed approach is verified by a simulation using a supply vessel model.

• Journal of Korean Academy of Nursing
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• v.44 no.6
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• pp.743-750
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• 2014

Purpose: The objective of this study was to provide a trend analysis of the prevalence of diabetes relative to the socioeconomic, lifestyle, and physiologic risk factors among Korean adults aged over 30 years for a 10-year period using data from the Korean National Health and Nutrition Examination Survey. Methods: Prevalence difference and the slope index of inequality were calculated for each risk factors using binomial regression by considering the repeated cross-sectional features of the data. The prevalence ratio and the relative index of inequality were calculated using log-binomial regression. Linear trend tests were performed using SAS 9.2. Results: Crude prevalence of diabetes increased over the 10-year period, and was higher for men than for women. It was very high for adults 60 years or over, consistently increasing over time. The prevalence among unemployed men, women with higher level of stress, women with hypertension, and adults with serum triglyceride levels over 135 mg/dL increased over the 10-year period in comparison with the respective control group. Conclusion: Considering the rapid economic development and associated lifestyle changes in Korea, action should be taken to control the prevalence of diabetes by both preventing and consistently monitoring these identified risk factors using a public-health approach.

• Korean Journal of Health Education and Promotion
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• v.32 no.2
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• pp.27-37
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• 2015

Objectives: As the increasing of the length of the lifespan, more recent policy interest are concerned with how many years of life are lived without functional disability or activity limitation. We investigated the relationship between deprivation and activity limitation at the 251 local authority level. Methods: The data were derived from the 2010 Census 10% sample data. Crude and age-standardized activity limitation rates by gender at the ages of 50 or over and deprivation index were calculated. Mapping and multiple linear regression analysis were applied to explore relationship between area activity limitation and area deprivation. Results: There were considerable differences in activity limitation rate across the 251 local authorities. Age-standardized activity limitation rate in both male and female were strongly associated with the level of area deprivation. Especially, low social class, male unemployment, or non-apartment residents at the local level were strong positive association with local authorities' age-standardized activity limitation. Conclusion: More policy attention is needed for tackling regional inequality in activity limitation among older adults.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.6
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• pp.780-785
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• 2007

This paper proposes the decentralized dynamic output feedback controller for discrete-time nonlinear interconnected systems using Takagi-Sugeno (T-S) fuzzy model. Through T-S fuzzy model of each subsystem, the decentralized dynamic output feedback controller is designed. By the closed-loop subsystems with controller, it represents the linear matrix inequality (LMI) for stability of whole interconnected system. The value of control gain are obtained by LMI. An example is given to show the experimentally verification discussed throughout the paper.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.4
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• pp.797-802
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• 2010

In this paper, a systematic procedure to design a nonlinear controller for nonlinear active magnetic bearing (AMB) systems is presented. To do this, we effectively convert the AMB system into a polytopic quasi-linear parameter varying (LPV) system, which is a representation of nonlinear state-space models and is described by the convex combination of a set of precisely known vertices. Unlike the existing quasi-LPV systems, the nonlinear weighting functions, which construct the polytopic quasi-LPV model of the AMB system by connecting the vertices, include not only state variables but also the input ones. This allows us to treat the input nonlinearity effectively. By means of the derived polytopic quasi-LPV model and linear matrix inequality (LMI) conditions, nonlinear controller that stabilizes the AMB system is obtained. The effectiveness of the proposed controller design methodology is finally demonstrated through numerical simulations.

• Journal of Preventive Medicine and Public Health
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• v.45 no.2
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• pp.113-121
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• 2012

Objectives: This study examined the trends in gender disparity in the self-rated health of people aged 25 to 64 in South Korea, a rapidly changing society, with specific attention to socio-structural inequality. Methods: Representative sample data were obtained from six successive, nationwide Social Statistics Surveys of the Korean National Statistical Office performed during 1992 to 2010. Results: The results showed a convergent trend in poor self-rated health between genders since 1992, with a sharper decline in gender disparity observed in younger adults (aged 25 to 44) than in older adults (aged 45 to 64). The diminishing gender gap seemed to be attributable to an increase in women;s educational attainment levels and to their higher status in the labor market. Conclusions: The study indicated the importance of equitable social opportunities for both genders for understanding the historical trends in the gender gap in the self-reported health data from South Korea.