• Journal of Life Science
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• v.17 no.2 s.82
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• pp.218-222
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• 2007

The purpose of this study is to evaluate the relationship between high sensitive C-reactive protein (hsCRP) and pulse transit time (PPT). Apparently healthy 233 subjects had been enrolled in the health promotion center of the Pusan National University Hospital from Jan. 29 to Feb. 26, 2004. They had no previous history of diabetes, hypertension and hyperlipidemia. Subjects were categorized according to tertiles of hsCRP level [Group 1: first tertile $(0.01\;{\sim}\;0.02\;mg/dl)$, Group 2: second tertile $(0.03\;{\sim}\;0.05\;mg/dl)$, Group 3: third tertile $(0.06\;{\sim}\;0.12\;mg/dl)$, and Group 4: Fourth tertile $(0.13\;{\sim}\;16.8\;mg/dl)$]. PTT body mass index (BMI), total cholesterol (T-C), LDL-cholesterol(LDL-C), blood sugar (BS), systolic blood pressure (sBP) and diastolic blood pressure (dBP) were significantly different among hsCRP groups (p<0.05). HsCRP is positively related with BMI, tryglyceride (TG), LDL, sBP and dBP (p<0.05), and negatively related with PTT and HDL-cholesterol (HDL-C) (p<0.05). PTT is significantly negatively related with hsCRP, T-C, TG, LDL-C, BS, dBP and sBP (p<0.05). The hsCRP and PTT were related before controlling BMI, T-C, LDL-C, sBP, and dBP, but not related after conkolling. The relationship between hsCRP and PTT depends on cardiovascular disease risk factors.

• Journal of Nutrition and Health
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• v.56 no.6
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• pp.702-713
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• 2023

Purpose: Depression is a prevalent mental health concern globally including South Korea. Given the growing interest in the relationship between diet and mental health, this study aimed to investigate the association between seafood consumption and depression among Korean adults. Methods: A cross-sectional analysis was conducted using data from the Korea National Health and Nutrition Examination Survey (KNHANES, 2014-2020). The study included 18,149 participants (7,541 men and 10,608 women) aged 19 years and older who completed the Patient Health Questionnaire (PHQ-9). Seafood intake levels were assessed using a oneday 24-hour dietary recall, and participants were categorized into three tertiles by gender. Depression status was determined using the PHQ-9 scores and the self-report of the doctor's diagnosis and treatment. Multivariable logistic regression analysis was performed to assess the association between seafood consumption and depression in both genders. Results: Participants with a higher seafood intake had a significantly lower nutritional density of total fat, while the nutritional density of omega-3 polyunsaturated fatty acids was significantly higher. The prevalence of depression was significantly lower in the highest tertile of seafood consumption compared to the lowest tertile in both men (p < 0.001) and women (p < 0.001). After adjusting for confounding factors, the highest tertile of seafood consumption demonstrated a decreased risk of depression compared to the lowest tertile in men (odds ratio [OR], 0.71; 95% confidence interval [CI], 0.51-0.99; p-trend = 0.020) and women (OR, 0.73; 95% CI, 0.59-0.91; p-trend = 0.004). Conclusion: The findings of this study suggest that consuming seafood rich in omega-3 fatty acids may potentially reduce the risk of depression in the adult population.

• The Journal of the Korea Contents Association
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• v.18 no.4
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• pp.444-453
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• 2018

The study addresses the analysis on the financial determinants of corporate research and development (R&D) expenditure in finance. Overall level of R&D spending was estimated as one of the top-tier on a global basis and a majority of the expenditure was invested by large domestic firms in private sector. Consequently, financial factors that influence R&D intensity were empirically tested in the first hypothesis by using conditional quantile regression model for firms listed in KOSPI stock market in the post-era of the global financial turmoil. Firms in the groups of high- and low-R&D intensity were statistically compared to detect financial differences in the second hypothesis which was accompanied by the test of multi-logit model that included firms without R&D outlay. Concerning the results of the hypothesis tests, R&D spending of the prior fiscal year, firm size, business risk and advertising expense overall showed statistically significant impacts to determine the level. As an extended study of [1] that had examined financial factors of R&D intensity at the macro-level, the results of the present study are anticipated to contribute to maximizing shareholders' wealth in advance or emerging capital markets, when applied to find an optimal level of R&D expenditure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.443-452
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• 2018

The purpose of this study was to investigate the utilization behavior of medical services according to the characteristics of socioeconomic status (SES) and prevalence by using the 6th National Health and Nutrition Survey data for adults over 25 years old. Frequency and technical statistical analysis, ANOVA, ${\chi}^2$-test, and regression analysis were performed using SPSS 23.0. The results were as follows: more female than male, 65 years old and over, high school graduate, and unemployed and income quintiles were similar. The SES score considering education level, function, and income quintiles was the highest at 7-8, and most of the respondents felt moderate about their subjective health condition. The mean number of prevalence was $1.07{\pm}1.497$, the mean utilization of outpatient services was $0.50{\pm}0.045$, and the mean number of inpatient services use was $0.12{\pm}0.454$. Depending on general characteristics, there was a significant difference between subjects with prevalence and subjective health conditions. Higher age was associated with lower education, skill level, income, and SES score, and average prevalence was associated with poor subjective health conditions. More serious prevalence was associated with greater utilization of inpatient services. More chronic prevalence was associated with utilization of outpatient services. In other words, higher SES score was associated with lower overall use of medical services. Lower SES score was associated with higher use of medical services. In conclusion, we must develop appropriate health education programs that can prevent diseases in groups with low socioeconomic characteristics. There is the need to construct and implement a community-based appropriate health service system so that proper medical services can be used.

• The Journal of the Korea Contents Association
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• v.14 no.12
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• pp.973-988
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• 2014

This study investigated one of the contemporary issues in the Korean capital market and two hypotheses of concern were tested on the financial determinants of profitability for the firms belonging to the Korean chaebols during the era of the post-global financial turmoil. The first hypothesis applying conditional quantile regression (CQR) estimation provided the evidence that leverage ratio, fixed asset utilization, and foreign ownership among the nine quantitative explanatory variables, had overall statistical significance relative to the book-valued profitability measure, while additional variables such as a firm's size, fixed and a proxy for the type of exchange market showed their strong impacts on the market-valued profitability indicator. Concerning the formulated 'extended' DuPont system, only two components of EBITDAEBIT and EMULTIPLIER revealed their prominent influence on ROE (Return on Equity) over the two tested periods (the years 2008 and 2012).

• The Journal of the Korea Contents Association
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• v.16 no.5
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• pp.399-409
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• 2016

Purpose: The purpose of this study was to examine factors influencing health related quality of life(HRQOL) in patients with hypertension. Methods: This study carried out secondary analysis using the data from the $5^{th}$ Korean National Health and Nutrition Examination Survey. Subject samples who were selected are 1,240 hypertension patients. The data were analyzed by using descriptive statistics, traditional classic regression, and quantile regression. Results: Restriction of activity, depressive mood, and subjective health status had only significant effects on HRQOL(p<.001). After quantile regression, depressive mood and subjective health status had only significant at 20%(p<.001), 40%(p<.001), and 60%(p<.01) of HRQOL. Perceived stress(p<.001) and regular exercise(p<.01) had only significant at 20% of HRQOL. Current drinking status had only significant at 20%(p<.001) and 80%(p<.01) of HRQOL. Conclusions: Quantile regression maybe a better statistical tool in understanding the heterogeneous effect of hypertension patient's HRQOL as health outcome. Therefore interventions are needed for patients with hypertension to manage each of the factors affecting the patient's perceived health status by each quantile.

• Journal of the Korean Data and Information Science Society
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• v.28 no.6
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• pp.1457-1469
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• 2017

Private education expenses is one of the key issues in Korea and there have been many discussions about it. Academically, most of previous researches for private education expenses have used multiple regression linear model based on ordinary least squares (OLS) method. However, if the data do not satisfy the basic assumptions of the OLS method such as the normality and homoscedasticity, there is a problem with the reliability of estimations of parameters. In this case, quantile regression model is preferred to OLS model since it does not depend on the assumptions of nonnormality and heteroscedasticity for the data. In the present study, the data from a survey on private education expenses, conducted by Statistics Korea in 2015 has been analyzed for investigation of the impacting factors for private education expenses. Since the data do not satisfy the OLS assumptions, quantile regression model has been employed in Bayesian approach by using gibbs sampling method. The analysis results show that the gender of the student, parent's age, and the time and cost of participating after school are not significant. Household income is positively significant in proportion to the same size for all levels (quantiles) of private education expenses. Spending on private education in Seoul is higher than other regions and the regional difference grows as private education expenditure increases. Total time for private education and student's achievement have positive effect on the lower quantiles than the higher quantiles. Education level of father is positively significant for midium-high quantiles only, but education level of mother is for all but low quantiles. Participating after school is positively significant for the lower quantiles but EBS textbook cost is positively significant for the higher quantiles.

• Journal of Nutrition and Health
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• v.47 no.5
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• pp.321-329
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• 2014

Purpose: The aim of this study was to determine the relationship between serum concentrations of 25-hydroxyvitamin D [25(OH)D] and chronic obstructive pulmonary disease (COPD) prevalence. Methods: The analysis was performed using data from the Fifth Korean National Health and Nutrition Examination Survey, a cross-sectional survey of the Korean civilian population conducted from 2010 to 2012. The analyses were restricted to males who were 40 years of age and above. Complex sample multiple logistic regression analyses were used to examine the associations of COPD prevalence with 25(OH)D and other factors. Results: $FEV_1/FEV_6$ varied significantly with smoking status, age, household income, education level, occupation, body mass index (BMI), and physical activity (p < 0.05). In univariate analysis, smoking status, BMI, household income, education level, and occupation showed association with COPD (p < 0.05), but vitamin D was not associated with COPD (p = 0.078). However, when adjusted with smoking status, household income, education level, occupation, BMI, age, and smoking index, the lowest quartile of 25(OH)D showed OR 1.643 (95% CI 1.161-2.236) compared to 3rd quartile (p = 0.024). Conclusion: A significant relationship was observed between serum concentration of 25(OH)D and COPD.

• Journal of Korean Society of Forest Science
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• v.108 no.3
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• pp.392-404
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• 2019

The purpose of this study was to identify the impact of various income sources on income inequality of forestry households. Data from the Forestry Household Economy Survey from 2013-2016 were analyzed using the Gini coefficient decomposition method via income source. In particular, the income inequality analysis of forestry households was broken down into separate analyses based on group, i.e., the whole of forestry households and the five income quintile classes. The results of the analyses showed that income inequality of forestry households is primarily affected by forestry and nonforestry incomes and income quintile class. Moreover, income inequality of the highest income quintile class was largely affected by forestry income compared with other sources of income, whereas that of other income quintile classes was largely affected by nonforestry income. Therefore, in order to reduce income inequality in forestry households, it is necessary to increase the proportion of forestry income in the lower four quintile classes. Given that the income of the lowest quintile class is negative, it is necessary to devise ways to improve the proportion and quantity of forestry income. At the same time, as forestry income increases, a policy alternative is also required to improve inequality in forestry income.

• Management & Information Systems Review
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• v.38 no.3
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• pp.1-19
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• 2019

This paper investigates the asymmetric effects of crude oil price uncertainty on industrial stock returns under different market conditions (bearish and bullish stock markets). We consider a quantile regression method using monthly oil volatility index, KOSPI and 22 industrial stock indices from May 2007 to February 2019. Especially, we take care of the positive and negative changes of the oil volatility index to analyze asymmetric effects of the oil price uncertainty for the bearish and bullish stock market conditions. During the bearish markets, the oil volatility index has relatively strong statistically significant negative effects on the industrial stock returns. These effects gradually decrease when the market conditions became more bullish markets. In particular, positive changes in the oil volatility index yields a further significant decrease in 12 industrial stock returns during the extreme bearish markets. Moreover, during the bullish markets, negative changes in the oil volatility index have statistically significant negative effects on the 12 industrial stock returns. From the empirical results, we see that participants of the Korean stock market are sensitive to bad news in a recession.