• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.3 s.49
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• pp.1-11
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• 2006

This paper presents a seismic fragility analysis method for a cable-stayed bridge with energy dissipation devices. Model uncertainties represented by random variables include input ground motions, characteristics of energy dissipation devices and the stiffness of cable-stayed bridge. Using linear regression, we established demand models for the fragility analysis from the relationship between maximum responses and the intensity of input ground motions. For capacity models, we considered the moment and shear force of the main tower, longitudinal displacement of the girder, deviation of the stay cables tension and the local buckling of the main steel tower as the limit states for cable-stayed bridge. As a numerical example, fragility analysis results for the 2nd Jindo bridge are presented. The effect of energy dissipation devices is also briefly discussed.

• Journal of Korea Society of Waste Management
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• v.35 no.8
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• pp.777-784
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• 2018

Since climate change increases the risk of extreme rainfall events, concerns on flood management have also increased. In order to rapidly recover from flood damages and prevent secondary damages, fast collection and treatment of flood debris are necessary. Therefore, a quick and precise estimation of flood debris generation is a crucial procedure in disaster management. Despite the importance of debris estimation, methodologies have not been well established. Given the intrinsic heterogeneity of flood debris from local conditions, a regional-scale model can increase the accuracy of the estimation. The objectives of this study are 1) to identify significant damage variables to predict the flood debris generation, 2) to ascertain the difference in the coefficients, and 3) to evaluate the accuracy of the debris estimation model. The scope of this work is flood events in Ulsan city region during 2008-2016. According to the correlation test and multicollinearity test, the number of damaged buildings, area of damaged cropland, and length of damaged roads were derived as significant parameters. Key parameters seems to be strongly dependent on regional conditions and not only selected parameters but also coefficients in this study were different from those in previous studies. The debris estimation in this study has better accuracy than previous models in nationwide scale. It can be said that the development of a regional-scale flood debris estimation model will enhance the accuracy of the prediction.

• Korean Journal of Biological Psychiatry
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• v.29 no.2
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• pp.46-55
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• 2022

Objectives Many studies have reported noticeable increases in the proportion of employees working either relatively short or relatively long hours. Such trends have been accompanied by an increasing concern that how much subjective mental well-being of employees would be influenced by their hours of work. The aim of this study was to investigate the association between work hours and clinically relevant depressive symptoms with demographic variables adjusted. Methods Participants were employees of a total of 56 private companies and local government organizations in Korea, aged 19 to 65 years. A self-report questionnaire that included items on working hour, job stress, levels of depression, and socio-demographic factors was administered to 15360 Korean employees, with 14477 valid responses. Hierarchical linear regression analyses, adjusted for sociodemographic factors, job related demographic factors, job stress, were used additionally to estimate the association between working hours and depressive scores. Results We found that working more than 40 hours per week correlated positively with the level of depressive symptoms after adjusting for demographic variables and the level of job stress. Furthermore, working 40 or fewer hours per week correlated negatively with the level of depressive symptoms. Being younger (β = -0.078, β = -0.099), being a female (β = 2.770, β = 1.268), and possessing a lower level of education (β = -0.315, β = -1.125) were significantly associated with higher level of depressive symptoms in all respondents. Conclusions Both of working excessively long or short hours is significantly associated with the prevalence of depressive symptoms. Establishing proper office hours for employees is critical to improving the quality of working conditions and maintaining good mental health in the workplace.

• Journal of Intelligence and Information Systems
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• v.28 no.2
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• pp.147-170
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• 2022

Although the number of patent which is one of the core outputs of technological innovation continues to increase, the number of low-value patents also hugely increased. Therefore, efficient evaluation of patents has become important. Estimation of patent lifespan which represents private value of a patent, has been studied for a long time, but in most cases it relied on a linear model. Even if machine learning methods were used, interpretation or explanation of the relationship between explanatory variables and patent lifespan was insufficient. In this study, patent lifespan (number of renewals) is predicted based on the idea that patent lifespan represents the value of the patent. For the research, 4,033,414 patents applied between 1996 and 2017 and finally granted were collected from USPTO (US Patent and Trademark Office). To predict the patent lifespan, we use variables that can reflect the characteristics of the patent, the patent owner's characteristics, and the inventor's characteristics. We build four different models (Ridge Regression, Random Forest, Feed Forward Neural Network, Gradient Boosting Models) and perform hyperparameter tuning through 5-fold Cross Validation. Then, the performance of the generated models are evaluated, and the relative importance of predictors is also presented. In addition, based on the Gradient Boosting Model which have excellent performance, Accumulated Local Effects Plot is presented to visualize the relationship between predictors and patent lifespan. Finally, we apply Kernal SHAP (SHapley Additive exPlanations) to present the evaluation reason of individual patents, and discuss applicability to the patent evaluation system. This study has academic significance in that it cumulatively contributes to the existing patent life estimation research and supplements the limitations of existing patent life estimation studies based on linearity. It is academically meaningful that this study contributes cumulatively to the existing studies which estimate patent lifespan, and that it supplements the limitations of linear models. Also, it is practically meaningful to suggest a method for deriving the evaluation basis for individual patent value and examine the applicability to patent evaluation systems.

• The Korean Journal of Applied Statistics
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• v.33 no.3
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• pp.335-345
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• 2020

This paper deals with the problem of estimating the log-transformed linear regression model to fit actual battle data from the Ardennes Campaign of World War II into the Lanchester model. The problem of determining a global solution for parameters and multicollinearity problems are identified and modified by examining the results of previous studies on data. The least squares method requires attention because a local solution can be found rather than a global solution if considering a specific constraint or a limited candidate group. The method of exploring this multicollinearity problem can be confirmed by a statistic known as a variance inflation factor. Therefore, the Lanchester model is simplified to avoid these problems, and the combat power attrition rate model was proposed which is statistically significant and easy to explain. When fitting the model, the dependence problem between the data has occurred due to autocorrelation. Matters that might be underestimated or overestimated were resolved by the Cochrane-Orcutt method as well as guaranteeing independence and normality.

• Journal of Internet of Things and Convergence
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• v.8 no.6
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• pp.99-113
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• 2022

This study is descriptive research to investigate the effects of COVID-19 stress, interpersonal (caregiver-patient) stress, and emotional labor on burnout in emergency room (ER) nurses during the COVID-19 pandemic. The data collection of this study was conducted from December 9 to 23, 2021 with ER nurses working at five tertiary general hospitals and general hospitals of Medical Center H. The data was collected with a questionnaire using tools measuring the subjects' general & job-related characteristics, COVID-19 stress, interpersonal(caregiver-patient) stress, emotional labor and burnout. The collected data was analyzed using the SPSS/WIN 25.0 statistical program for frequency analysis, descriptive statistical analysis, independent sample t-test, one-way ANOVA, Scheffé test, correlation analysis, and multiple regression analysis. The average score of COVID-19 stress in ER nurses was 3.64, interpersonal(caregiver-patient) stress 4.35, emotional labor 3.38, and burnout 3.44. As a result of analyzing differences according to general & job-related characteristics, burnout showed a significant difference according to gender, marital status, total clinical experience, and working organization. And burnout showed a significant positive correlation with COVID-19 stress, interpersonal stress and emotional labor. As a result of multiple linear regression analysis, regional emergency medical centers and local emergency medical centers among the work organization types, interpersonal stress, COVID-19 stress, and gender and the explanatory power was 28.6%. Through these results, we intend to provide basic data for the development of an intervention program to prevent burnout of emergency room nurses and improve nursing performance at the time of a new infectious disease pandemic.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4758-4767
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• 2015

This study investigates the relationship between occupational stress, depression, drinking among heavy industrial male workers. The participants of this study were 312 workers in a local heavy industry. The data were collected by self-report using questionnaires from May to June, 2014. The data were analyzed using descriptive statistics. t-test, ANOVA, and pearson correlation coefficient, scheffe test, stepwise multiple linear regression with the SPSS/WIN 20.0 program. The total mean scores of occupational stress on the subjects were $53.77({\pm}6.33)$, depression were $12.10({\pm}7.44)$, drinking were $10.32({\pm}7.55)$. The study showed that drinking is positively correlated with occupational stress, depression. Also drinking explained 15.9% of occupational stress in heavy industrial male workers. This study provides baseline data for the preparation of management strategies that can address the occupational stress, depression, drinking of heavy industrial male workers.

• Korean Journal of Health Education and Promotion
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• v.32 no.3
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• pp.23-31
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• 2015

Objectives: The contribution of health behavior is high in the mortality variation. Mortality variation can be decreased through the policies and programs for improving health behavior. We investigated that health behaviors effected with standardized mortality in community. Methods: We examined the distribution of health determinant factors and correlation analyzed between factors and performed multiple linear regression. Data were collected from 2012 Community Health Survey in 253 communities, annual regional statistics, and statistics from Statistics Korea. Results: This study defined that the variation of standardized mortality and there are exist inequality level of health determinant factors in 253 communities. This study showed that the higher standardized mortality explained through health behavior factors of the current smoking rate, walking exercise rate and diagnosis of hypertension or diabetes rate after adjusted other factors(adjusted $R^2=0.709$, p<0.001). Conclusions: Smoking, walking exercise and diagnosis chronic disease affecting on the regional variation of standardized mortality. These factors can be improved by the local residents themselves.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.3
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• pp.237-246
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• 2021

The ILI, developed by the IWA (International Water Association), has been used in many countries as an indicator of water leakage. In Korea, the revenue water has been used as a performance indicator for waterworks although there is an opinion to replace it with the ILI. Hence, it has been necessary to investigate whether the ILI can replace the revenue water in Korea. The four main operating indicators (i.e., water service population, profit-loss ratio, fiscal self-reliance, and aged pipe rate) of 162 Korean waterworks were compared with the ILI with the linear regression method. Local water authorities with more than 1 million water service population, with more than 60% profit-loss ratio, more than 40% and less than 60% fiscal self-reliance, and more than 20% aged pipe rate showed meaningful correlation between the four parameters and the ILI. In the remaining cases, their correlations were little or weak. This means that using the ILI may not be an efficient method to represent the performance of the water supply system in Korea because of the lack of UARL (Unavoidable Annual Real Losses) data accuracy. To use the ILI in Korea, it will be required to carry out an additional research to accumulate reliable CARL (Current Annual Real Losses) and UARL data in the future.

• Journal of Environmental Health Sciences
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• v.47 no.2
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• pp.131-143
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• 2021

Objectives: This study aims to investigate the atmospheric concentration of polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) and the urinary concentration of biomarkers in residents near the Shinpyeong·Jangrim Industrial Complex to compare them with those of residents in a control area. Methods: Hazardous air pollutants (PAHs and VOCs) were measured in an exposure area (two sites) and a control area (one site). Urine samples were collected from residents near the industrial complex (184 persons) and residents in the control area (181 persons). Multiple linear regression analysis was used to identify which factors affected the concentration of PAHs and VOCs metabolites. Results: The average atmospheric concentration of PAHs in Shinpyeong-dong and Jangrim-dong was 0.45 and 0.59 ppb for pyrene, 0.15 and 0.16 ppb for benzo[a]pyrene, and 0.29 and 0.35 ppb for dibenz[a,h]anthracene. The average atmospheric concentration of VOCs was 1.10 and 0.99 ppb for benzene, 8.22 and 11.30 ppb for toluene, and 1.91 and 3.05 ppb for ethylbenzene, respectively. The concentrations of PAHs and VOCs in residents near the Shinpyeong·Jangrim Industrial Complex were higher than those of residents in the control area. Geometric means of urinary 2-hydroxyfluorene, 1-hydroxypyrene, methylhippuric acid, and mandelic acid concentrations were 0.45, 0.22, 391.51, and 201.36 ㎍/g creatinine, respectively. Those levels were all significantly higher than those in the control area (p<0.05). In addition, as a result of multiple regression analysis, even after adjusting for potential confounding factors such as gender and smoking, the concentration of metabolites in urine was high in residents near the Shinpyeong·Jangrim Industrial Complex. Conclusion: The results of this study show the possibility of human exposure to VOCs in residents near the Shinpyeong·Jangrim Industrial Complex. Therefore, continuous monitoring of the local community is required for the management of environmental pollutant emissions.