• Korean Journal of Social Welfare
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• v.63 no.1
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• pp.187-215
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• 2011

This study examined the longitudinal relationship between depressive symptoms and alcohol use based on the tension reduction hypothesis and the intoxication hypothesis considering for path of depressive symptoms on alcohol use and vice versa simultaneously. And this study examined the effect of psychosocial behavior factors (i.e. smoking level, self-esteem, satisfaction with family relationships, and satisfaction with social relationships) on depressive symptoms and alcohol use. Using the data on the Korea Welfare Panel Study for the 1st, 2nd, and 3rd years, this study were estimated using the Latent Growth Curve Model which is helpful for examining differences between the two. The results are as follows: the initial level of alcohol use had a positive impact on the rate of change in depressive symptoms, thereby supporting the intoxication hypothesis. Second, self-esteem and satisfaction with family relationships act as variables with the biggest effect on the initial level and the rate of change in depressive symptoms, whereas other psychosocial behavior factors such as smoking level and satisfaction with social relationship exert the largest influence over the initial level and the rate of change in alcohol use. This study has implications in that it clarified the confused relationship mechanism between alcohol use and depressive symptoms the two. Based on the finding of the study, political and practical implications were discussed.

• Journal of Korea Water Resources Association
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• v.39 no.5 s.166
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• pp.395-403
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• 2006

This study suggests the use of a simple method, called the unit concentration response function(UCRF) for predicting travel time and dispersion of pollutants with the minimum information of study area instead of numerical models which are widely used In the Previous studies. However, the numerical models require time-consuming, tedious effort, and many data sets. So we derive the UCRF using some components such as travel time, peak concentration, and passage time of pollutant etc. We use the regression equation for the estimations of components which were developed from the investigations of many river basins in USA. This study used the regression equaiton for the UCRF to the accident of Dichloromethane leak into the Nakdong River occurred on June 30, 1994 and applied the UCRF for the predictions of travel time and dispersion. The predictions were compared with the results by QUAL2E model. The results by the regression equaiton and QUAL2E model had a good agreement between observed and simulated concentrations. Therefore, the regression equation for the UCRF which can simply estimate travel time and concentration of pollutants showed its applicability for the ungaged basin.

• Ecology and Resilient Infrastructure
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• v.1 no.2
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• pp.49-60
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• 2014

Fish assemblages play an integral role in stream ecosystem and are influenced by stream environmental conditions and habitat disturbances. Fish community structures and habitat parameters of U.S. EPA rapid bio-assessment protocol were surveyed to investigate the effect of stream environment and habitat disturbance on fish communities at 13 study sites in the Gapyeong Stream, a typical gravel-bed stream. Principal component analysis (PCA) based on data from habitat assessment at each study site indicated that the study sites were differentiated by habitat parameters such as embeddedness, velocity/depth regime and sediment deposition, which were related with bed slope. A total of 46 species belonging to 12 families were collected in the Gapyeong Stream. A dominant species was Zacco koreanus, subdominant species was Z. platypus. Hierarchical cluster analysis based on species abundance classified fish communities into the three main groups along the stream longitudinal change. Non-metric multidimensional scaling (NMDS) portrayed that fish community structures were related to major habitat parameters, i.e., epifaunal substrate/available cover, embeddedness, velocity/depth regime, sediment deposition, channel alternation and frequency of riffles. These results suggested that fish community structures were primary affected by the longitudinal environmental changes, and those were modified by habitat disturbance in the Gapyeong Stream, a gravel-bed stream.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.509-519
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• 2016

This study intends to examine how the subjective health perception of drinkers influences the depression trajectory change by using longitudinal data for elderly drinkers. This study has set up a balanced panel by combining the results from "Aging study panel research" conducted in the year 2006 (1st), 2008 (2nd), 2010 (3rd), 2012 (4th). A total of 543 elderly drinkers, who have responded to each research have been selected as targets for the final analysis. In the analyses, descriptive statistics and Latent Growth Modeling were conducted to examine the causal relationship between the observed and latent variables. The results are as follows: First, it was found that there was a negative correlation-with statistical significance-between the initial value of subjective health perception and the initial status of depression symptom. Second, there was a positive correlation between the initial value of subjective health perception and the changes of depression symptom. This indicates that elderly drinkers with high health perception usually have high degree of depression change; however, this does not mean it was statistically significant. Third, there was a statistically significant correlation between subjective health perception change and depression symptom change. It was found that the depression change level would be low if the subjective health perception change level was high. Thus, we can assume that the depression symptoms of elderly drinker c would slow down if the subjective health perception level increases.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.118-124
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• 2017

In this study, a numerical simulation was performed using commercial code Fluent(v.17.1). The underground Combined Cycle Power Plant (CCPP) was simplified to analyze the methane gas leakage with the crack size and position. In addition, extensive numerical simulations were carried out for different crack sizes from 10 mm to 20 mm. The crack position is the gas leakage, which is assumed to be near the pipe elbow and the gas turbine. A total of 4 cases were compared and analyzed. To analyze the gas leakage, the concept of the Lower Flammable Limit (LFL) was applied. The leakage distance was defined in the longitudinal direction, and the transverse direction was estimated and quantitatively analyzed. As a result, the leakage distance in the longitudinal direction varies by 52.3 % depending on the crack size at the same crack position. Moreover, the maximum difference was 34.8 % according to the crack position when the crack sizes are identical. As jet flow impacts on the obstacle and changes its direction, the recirculation flows are formed. These results are expected to provide useful data to optimize the location and number of gas detections in confined spaces, such as underground CCPP.

• Allergy, Asthma & Immunology Research
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• v.10 no.6
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• pp.614-627
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• 2018

Purpose: Asthma is a heterogeneous disease that responds to medications to varying degrees. Cluster analyses have identified several phenotypes and variables related to fixed airway obstruction; however, few longitudinal studies of lung function have been performed on adult asthmatics. We investigated clinical, demographic, and inflammatory factors related to persistent airflow limitation based on lung function trajectories over 1 year. Methods: Serial post-bronchodilator forced expiratory volume (FEV) 1% values were obtained from 1,679 asthmatics who were followed up every 3 months for 1 year. First, a hierarchical cluster analysis was performed using Ward's method to generate a dendrogram for the optimum number of clusters using the complete post-FEV1 sets from 448 subjects. Then, a trajectory cluster analysis of serial post-FEV1 sets was performed using the k-means clustering for the longitudinal data trajectory method. Next, trajectory clustering for the serial post-FEV1 sets of a total of 1,679 asthmatics was performed after imputation of missing post-FEV1 values using regression methods. Results: Trajectories 1 and 2 were associated with normal lung function during the study period, and trajectory 3 was associated with a reversal to normal of the moderately decreased baseline FEV1 within 3 months. Trajectories 4 and 5 were associated with severe asthma with a marked reduction in baseline FEV1. However, the FEV1 associated with trajectory 4 was increased at 3 months, whereas the FEV1 associated with trajectory 5 was persistently disturbed over 1 year. Compared with trajectory 4, trajectory 5 was associated with older asthmatics with less atopy, a lower immunoglobulin E (IgE) level, sputum neutrophilia and higher dosages of oral steroids. In contrast, trajectory 4 was associated with higher sputum and blood eosinophil counts and more frequent exacerbations. Conclusions: Trajectory clustering analysis of FEV1 identified 5 distinct types, representing well-preserved to severely decreased FEV1. Persistent airflow obstruction may be related to non-atopy, a low IgE level, and older age accompanied by neutrophilic inflammation and low baseline FEV1 levels.

• Korean Journal of Family Social Work
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• no.53
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• pp.161-198
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• 2016

This study examined how previous financial and time transfers from mothers to their adult children affect co-residence of elderly mothers and their adult children in South Korea. This study employed multi-level logistic analysis considering hierarchical relationship structures between mothers and their adult children. A sample of 1,925 elderly mothers and 7,460 adult children was extracted from data which were from the first wave (in 2006) to the forth wave (in 2012) of Korean Longitudinal Study of Ageing (KLoSA). The result of the analysis suggested that past financial transfer from mothers to their adult children was not significantly associated with co-residence between elderly mothers and their adult children. However, likelihood of co-residence increased with the amount of time transfer, which was measured by unit of time for elderly mothers' caring for their grandchildren. This study discussed that long-term reciprocal relationships between elderly mothers and their adult children are built by intergenerational support relationships. However, the result that showed only grandmaternal child care affected intergenerational co-residence implies that intergenerational care may play an important role in intergenerational reciprocal relationships. Through these findings, this study suggested theoretical, practical, and policy implications.

• Korean Journal of Social Welfare Studies
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• v.47 no.1
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• pp.261-290
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• 2016

The purpose of this study was to examine how previous grandmaternal child care affects contacts between older mothers and their adult children. This study especially focused on intergenerational long-term reciprocity relationships. In this study, data from the first wave (in 2006) to the forth wave (in 2012) of Korean Longitudinal Study of Ageing yielded a sample of 1,925 elderly mothers and 7,460 adult children. This study employed multi-level analyses considering hierarchical structures between the mothers and their adult children. In this study, past grandmaternal child care was measured by providing care behavior and unit of time for care. Intergenerational contacts was measured by frequency of face-to-face and non-face-to-face contacts. The results showed that adult children who previously received child care from their mothers were more likely to contact to their mothers. Additionally, the increasing amount of time for elderly mothers to provide care to their grandchildren led to more frequent contacts between elderly mothers and their adult children. The findings proved that grandmaternal child care was in important position in reciprocal relationships between elderly mothers and their adult children. Through these results, this study suggested theoretical, policy, and practical implications.

• Journal of the Korea Society of Computer and Information
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• v.25 no.6
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• pp.171-181
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• 2020

This is an empirical study that analyzes factors affecting the work-family compatibility of female wage workers with underage children. The analysis was conducted with 1,113 women from the 7th wave of the Korean Longitudinal Survey of Women & Families by Korean Women's Development Institute. As for research methods, multiple regression analysis was used in order to analyze the effects of 'social support(home support, maternity protection support, childcare and education services)', 'job characteristics', 'socio-demographic variables' and 'husband characteristics' on 'work-family compatibility and conflict'. As a result, it was analyzed that the husband's support for work life, gender inequality at work and women's educational training were the factors that strengthen work-family compatibility. It was also analyzed that gender inequality, use of childcare and education facility, number of underage children, age of husband, husband's satisfaction with caring support and husband's support for work life were the factors that cause conflict between work and family. Thus, if the policy of strengthening the work-family compatibility is a long-term policy, it appears that it is necessary to supplement and strengthen policies that can reduce conflict factors in the short term. It is hoped that the results of the study will be used as objective and academic data to strengthen the maternity protection and work-family compatibility of female workers with underage children.

• Journal of vocational education research
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• v.37 no.4
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• pp.67-89
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• 2018

The purpose of this study is to analyze the role of career flexibility on employment status, career growth, and job satisfaction longitudinally. Demographic information(gender, age, parent's income level, and students' perceived financial states of family), vocational identity, employment status, career growth, and job satisfaction at 1, 2, and 3 years after the first data collection with a sample of 259(time 1), 229(time 2), 182(time 3) were collected respectively. Multivariate regression and logistic regression analysis were performed. Results showed that in-breadth career exploration positively predicted to employment status at time 1, 2, 3 consistently and career flexibility also positively predicted to employment status at time 2, 3. The longitudinal effect of career flexibility was found that the expectancy of career flexibility had shown to have stronger effect. In addition, career growth was influenced by in-depth career exploration at time 2, 3. On the other hand, no variables were related to job satisfaction in this study. Results of the current study provided the new insights for career education and limitation and future suggestions were discussed.