• Tuberculosis and Respiratory Diseases
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• 제85권4호
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• pp.349-357
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• 2022

Background: The most consistently identified mortality determinants for the new coronavirus 2019 (COVID-19) infection are aging, male sex, cardiovascular/respiratory diseases, and cancer. They were determined from heterogeneous cohorts that included patients with different disease severity and previous conditions. The main goal of this study was to determine if activities of daily living (ADL) dependence measured by Barthel's index could be a predictor for COVID-19 mortality. Methods: A prospective cohort study was performed with a consecutive sample of 340 COVID-19 patients representing patients from all over the northern region of Portugal from October 2020 to March 2021. Mortality risk factors were determined after controlling for demographics, ADL dependence, admission time, comorbidities, clinical manifestations, and delay-time for diagnosis. Central tendency measures were used to analyze continuous variables and absolute numbers (proportions) for categorical variables. For univariable analysis, we used t test, chi-square test, or Fisher exact test as appropriate (α=0.05). Multivariable analysis was performed using logistic regression. IBM SPSS version 27 statistical software was used for data analysis. Results: The cohort included 340 patients (55.3% females) with a mean age of 80.6±11.0 years. The mortality rate was 19.7%. Univariate analysis revealed that aging, ADL dependence, pneumonia, and dementia were associated with mortality and that dyslipidemia and obesity were associated with survival. In multivariable analysis, dyslipidemia (odds ratio [OR], 0.35; 95% confidence interval [CI], 0.17-0.71) was independently associated with survival. Age ≥86 years (pooled OR, 2.239; 95% CI, 1.100-4.559), pneumonia (pooled OR, 3.00; 95% CI, 1.362-6.606), and ADL dependence (pooled OR, 6.296; 95% CI, 1.795-22.088) were significantly related to mortality (receiver operating characteristic area under the curve, 82.1%; p<0.001). Conclusion: ADL dependence, aging, and pneumonia are three main predictors for COVID-19 mortality in an elderly population.

• 산업융합연구
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• 제22권6호
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• pp.61-71
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• 2024

본 연구의 목적은 아동의 모 애착과 행복감 간의 관계에서 자아탄력성과 스마트폰 의존도의 매개효과를 검증하는 것이다. 이를 위해 육아정책연구소(Korea Institute of Child Care and Education)에서 조사한 한국 아동패널 12차 데이터를 활용하였고, 그 중 1,143명을 연구대상자로 선정했다. 분석 방법은 빈도분석, 기술통계분석, 상관분석을 실시하였고, Process Macro Model Number 4 분석을 활용하여 매개효과를 분석하였다. 스마트폰 의존도와 자아탄력성의 간접효과는 부트스트래핑(Bootstrapping)를 적용하여 검증하였다. 연구결과는 다음과 같다. 첫째, 모 애착은 아동의 행복감을 증가시키는 것으로 나타났다. 둘째, 아동의 모 애착과 행복감 간의 관계에서 자아탄력성의 부분 매개효과를 확인했다. 셋째, 아동의 모 애착이 행복감에 미치는 영향에서 스마트폰 의존도는 부분 매개효과를 보이는 것으로 나타났다. 이러한 연구결과를 바탕으로 아동의 행복감을 증진시킬 수 있는 다양한 실천적 과제들을 제시했다.

• 보건의료산업학회지
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• 제9권3호
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• pp.145-157
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• 2015

Objectives : This study identified factors that influenced social nicotine dependence in university students using descriptive methods. Methods : Data were collected 429 university students from 2 universities in B metropolitan city. The analytical methods were the t-test, ANOVA, Scheffe's test, Pearson's Correlation Coefficient and multiple regression analysis. Results : There were significant differences in social nicotine dependence according to gender (t=3.359, p=.001), smoking status (t=8.915, p=.000), religion (t=3.841, p=.022), economic status (t=3.632, p=.027) and grade (t=8.466, p=.000). Social nicotine dependence was weakly correlated with anxiety (r=.113, p<.05). Meaningful variables that explain social nicotine dependence were anxiety, self-efficacy self-esteem, female, smokers and no religion. Conclusions : It is necessary to develop a comprehensive smoke-free policy that considers social nicotine dependence to improve the cultural and social awareness of the associated health hazards of smoking, and to develop smoking cessation education and smoking prevention programs that improve the self-efficacy and self-esteem of university students.

• 산업융합연구
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• 제21권7호
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• pp.65-73
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• 2023

본 연구는 청소년의 학업무기력과 스마트폰 의존의 관계를 파악하고 자아존중감과 친구관계의 병렬매개효과를 검증하였다. 이를 위해 한국청소년정책연구원에서 수행한 한국아동·청소년 패널조사 2018(KCYPS) 4차 자료를 활용하였으며, 조사에 응답한 청소년 중 무응답 및 이상 값 346명을 제거한 뒤 2,244명을 분석에 활용하였다. 자료분석을 위해 통계패키지 프로그램 SPSS WIN 25.0과 Hayes(2013)의 PROCESS Macro V 3.5를 활용하였으며, 다음과 같은 결과를 도출했다. 첫째, 청소년의 학업무기력은 스마트폰 의존에 정(+)적인 영향이 나타났다. 둘째, 청소년의 학업무기력과 스마트폰 의존의 관계에서 자아존중감은 매개하는 것으로 나타났다. 셋째, 청소년의 학업무기력과 스마트폰 의존의 관계에서 친구관계는 매개하는 것으로 나타났다. 이를 토대로 청소년의 스마트폰 의존을 감소시키기 위한 실천적·정책적 제언과 연구의 한계점을 극복하기 위한 후속 연구를 제안했다.

• 대한산업공학회지
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• 제33권4호
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• pp.410-418
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• 2007

This article suggests the methods to investigate adverse movement across global stock markets arising from insolvency of subprime mortgage in U.S. Our application deals with asymptotic tail dependence of daily stock index returns (KOSPI, DJIA, Shanghai Composite) of three countries; Korea, U.S., and China, over specific period via extreme value theory and copula functions. Daily stock index returns among three countries show higher extremal dependence during the period exposed to systematic shock. We confirm that extreme value theory and copula functions have potential to well describe the extreme dependence between three countries' daily stock index returns.

• Journal of Korea Trade
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• 제24권3호
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• pp.37-54
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• 2020

Purpose - This study is to investigate the determinants of suppliers' dependence on buyers in the home country by developing a theoretical model of innovative activities. The high dependence of auto parts suppliers on a single local buyer in South Korea due to firm ownership issues and incremental innovation is examined using data from a set of organizations that supply intermediate goods to this automotive manufacturer. Furthermore, we tested the moderating effect of FDI and global knowledge sourcing on the relationship between firm ownership and suppliers' dependence on the local buyer. Design/methodology - To test the hypotheses, we examined a sample of 101 suppliers over 10 years in the Korean automobile parts industry. In this empirical analysis, we utilized a fixed-effects generalized least squares model using panel data. Findings - In this study, domestic firms (automobile parts suppliers) were more dependent on a single local buyer (automobile assembler) than foreign-owned suppliers operating in Korea. In addition, incremental innovation was the mediating mechanism between domestic firms and dependence on the local buyer. To reduce this dependence on the buyer, we suggest two different international strategies: geographical diversification through FDI and global knowledge sourcing. Originality/value - Previous studies showed that asymmetric dependence between firms has many adverse effects. This study proved that domestic and foreign-owned suppliers have different levels of dependence on local buyers due to their heterogeneous characteristics and business strategies. We distinguish two different types of innovation - radical innovation and incremental innovation - that previous studies have often treated as equal when it comes to firm autonomy. Finally, we propose that both FDI and international knowledge sourcing as global strategies to weaken suppliers' asymmetric dependence on a single buyer.

• Communications for Statistical Applications and Methods
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• 제27권1호
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• pp.79-95
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• 2020

The globalization of financial markets has broadened investment opportunities. International investors' investment portfolios consist of financial instruments from various countries; consequently, the risks associated with economic dependence among countries should be carefully considered. Step-down equity-linked securities (ELS) are a structured financial product that have recently become popular among Korean investors. Payoffs are based on two or three stock indices from different regions; therefore, dependence between the indices should be reflected in the risk analysis. In this study, we consider a regime-switching copula model to describe the joint behavior of two stock indices- the Eurostoxx50 and the Hang Seng China Enterprises Index (HSCEI). These indices are commonly used as underlying assets of step-down ELS. Using historical data, we analyze the risk associated with step-down ELS through the probabilities of early redemption. A regime-switching copula model can accommodate complicated dependence. Thus, it should be considered in the risk analysis of step-down ELS.

• 대한수학회지
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• 제35권4호
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• pp.945-960
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• 1998

This paper is concerned with investigating the asymptotic behavior of end effects for a generalized heat conduction problem with an added dissipation term defined on a three-dimensional semi-infinite cylinder. With homogeneous Dirichlet conditions on the lateral surface of the cylinder it is shown that solutions either grow exponentially or decay exponentially in the distance from the finite end of the cylinder. In particular, to render decay estimate explicit, we pattern after the analysis of Payne and Song [13, 15]. The continuous dependence effect of perturbing the equations parameters is also investigated.

• 호남수학학술지
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• 제25권1호
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• pp.117-127
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• 2003

In this note we perform an extreme point analysis on two natural definitions of negative quadrant dependence of three random variables and examine how different these two notions of dependence. We also characterize some special distributions which are both negatively lower orthant dependent and negatively upper orthant dependent.

• 생물정신의학
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• 제10권2호
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• pp.159-167
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• 2003

Objective:Under the hypothesis that 5-HTTLPR polymorphism plays some role in the susceptibility or vulnerability of some subgroup of alcohol dependence, associations of 5-HTTLPR polymorphism with alcohol dependence were examined. Method:This association analysis included 109 Korean alcohol dependent and 113 Korean control subjects. DNA of all subjects were genotyped for the biallelic functional polymorphism in the 5-HTTLPR. Considering the likelihood of heterogeneity in the alcohol dependence phenotype, alcohol dependent subjects were subgrouped by onset age, family history of alcohol dependence and severity of withdrawal symptoms. Results:There were no significant differences in the frequencies of either the 5-HTTLPR genotype or the short vs. long allele in alcohol dependent and control subjects. The frequency of the S allele and S-carrier (LS or SS genotype) was significantly increased in the early onset alcohol dependent subjects and the familial alcohol dependent subjects compared with that in the control subjects. Conclusion:The results suggest that the 5-HTT 'S' promoter polymorphism is associated with an increased susceptibility or vulnerability to develop early onset alcohol dependence and familial alcohol dependence, which characterize Cloninger's type 2 alcohol dependence.