• The Journal of Korean Association of Computer Education
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• v.10 no.4
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• pp.93-102
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• 2007

The present study is to investigate the elements of e-learning strategies affecting the levels of participation, achievement and satisfaction for learners who participated in the university blended learning environment. For this, 58 subjects were recruited who participated in the blended learning class at K university. E-learning strategies, achievement and satisfaction levels were measured for data collection, and the level of participation was measured by analyzing the LMS log-in database. For data analysis, first, means and standard deviation were computed to find the level of e-learning strategies of the subjects. Second, linear regression analysis was conducted to find the e-learning strategies that could estimate the levels of achievement, participation and satisfaction. As a result, variables to estimate the achievement level included time management strategy and overload management strategy. Variables to estimate the participation level included self-directed strategy, time management strategy and overload management strategy. Finally, variables to estimate the satisfaction level included multiple discussion management strategy, asynchronous management strategy and sociality. Based on these estimated variables, the author suggested some ideas to increase the educational effectiveness.

• Journal of Digital Convergence
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• v.16 no.7
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• pp.493-509
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• 2018

This study was performed to compare the effects of health behaviors, dietary habits, and psychological health on metabolic syndrome (MS) between young adults living in one-person households (OPHs) and multiple-person households (MPHs). The data from the Korean National Health and Nutrition Examination Survey (KNHANES), which was conducted in 2014 and 2016 were used. The subjects were 2,682, who were 20 to 39 years old. The data were analyzed using complex sample Rao-Scott ${\chi}^2-tests$, t-tests, and multiple logistic regression using SPSS 23.0 software. Sex, age, obesity, and subjective health status were associated with MS in young adults living in either OPHs or MPHs. Breakfast consumption frequency, eating alone, food label use, stress, and depression were associated with MS only in young adults living in OPHs. Thus, these differentiated risk factors of MS should be considered, when health promotion strategies and interventions are planned for young adults living in OPHs. Also, further studies are needed to evaluate the effectiveness of the strategies or interventions.

• Korean Journal of Remote Sensing
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• v.37 no.6_1
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• pp.1739-1756
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• 2021

Atmospheric nitrogen dioxide (NO₂) is mainly caused by anthropogenic emissions. It contributes to the formation of secondary pollutants and ozone through chemical reactions, and adversely affects human health. Although ground stations to monitor NO₂ concentrations in real time are operated in Korea, they have a limitation that it is difficult to analyze the spatial distribution of NO₂ concentrations, especially over the areas with no stations. Therefore, this study conducted a comparative experiment of spatial interpolation of NO₂ concentrations based on two linear-regression methods(i.e., multi linear regression (MLR), and regression kriging (RK)), and two machine learning approaches (i.e., random forest (RF), and support vector regression (SVR)) for the year of 2020. Four approaches were compared using leave-one-out-cross validation (LOOCV). The daily LOOCV results showed that MLR, RK, and SVR produced the average daily index of agreement (IOA) of 0.57, which was higher than that of RF (0.50). The average daily normalized root mean square error of RK was 0.9483%, which was slightly lower than those of the other models. MLR, RK and SVR showed similar seasonal distribution patterns, and the dynamic range of the resultant NO₂ concentrations from these three models was similar while that from RF was relatively small. The multivariate linear regression approaches are expected to be a promising method for spatial interpolation of ground-level NO₂ concentrations and other parameters in urban areas.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3353-3360
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• 2015

This study was conducted to identify the BMI of enlisted soldiers, to understand the difference between their BMI and that of other men in their age group, and to identify the influence factors of enlisted soldiers' BMI change. The survey has been conducted self-evaluation questionnaire from 23 Feb. 2009 to 31 Mar. 2009 from 4 different forces as methods. Independent-sample T-test, chi-square test and multiple linear regression analysis were used for statistical analysis from 301 collected data. As a result of surveying enlisted soldiers' BMI, their obesity rate 18.6% was lower than 22.1% of other men in their age group. In terms of health behavior, the underweight&normal weight group(2.39) showed higher diet score than the overweight group(2.13), showing that the underweight&normal weight group ate relatively slowly, less spicy and less sweet food compared to the overweight group. The overweight group(2.25) showed lower satisfaction with their body type than the underweight&normal weight group(2.98), while the overweight group(4.01) showed a significantly higher score than the underweight&normal weight group(3.37) for weight control activity. The influence factors of BMI change were diet habit, subjective perception of body type, and weight control activity. In order to improve of enlisted soldiers' BMI, it would be necessary to improve the food service and the snack bars for interventional control of food that influence obesity, rather than personal effort, in addition, education for right body-shape perception and encouraging on weight control activity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.461-470
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• 2020

This study analyzed the determinants of land compensation costs using the CALS (Continuous Acquisition & Life-Cycle Support) system to generate data for the construction (planning, design, building, management) process. For analysis, variables used in the related research on land costs were used, which included eight variables (Land Area, Individual Public Land Price, Appraisal & Assessment, Land Category, Use District 1, Terrain Elevation, Terrain Shape, and Road). Also, the variables were analyzed using the machine learning-based Xgboost algorithm. Individual Public Land Price was identified as the most important variable in determining land cost. We used a linear multiple regression analysis to verify the determinants of land compensation. For this verification, the dependent variable included was the Individual Public Land Price, and the independent variables were the numeric variable (Land Area) and factor variables (Land Category, Use District 1, Terrain Elevation, Terrain Shape, Road). This study found that the significant variables were Land Category, Use District 1, and Road.

• Journal of Nutrition and Health
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• v.47 no.2
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• pp.113-123
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• 2014

Purpose: Vitamin D has been known to play an important role in the central nervous system and brain functions in the human body, and cumulative evidence has shown that vitamin D deficiency might be linked with various mental health conditions. Epidemiologic studies have shown that vitamin D deficiency may be associated with higher risk of depression in the US and European populations. However, limited information is available regarding the association between vitamin D status and depression in the Korean population. The objective of this study was to examine the associations between vitamin D levels and prevalence of depression. Methods: We conducted a cross-sectional analysis using nationally representative data from the 2008-2010 Korean National Health and Nutrition Examination Survey from which serum 25-hydroxyvitamin D concentrations were available. A total of 18,735 adults who had available demographic, dietary, and lifestyle information were included in our analysis. We defined "depression" with a diagnosis by a physician. "Depressed condition" was defined as having feelings of sadness or depression without diagnosis by a physician. Results: The prevalence of depression was 1.63% and 5.43% in Korean men and women, respectively; 12.5% of men and 26.1% of women were defined as the group having depressed conditions. In multivariate logistic regression models, no significant associations were observed between vitamin D status and prevalence of depression or depressed conditions in Korean men and women. Conclusion: We found no association between vitamin D insufficiency and depression/depressed conditions in Korean adults. Future large prospective studies and randomized controlled trials are needed to confirm this relationship.

• Journal of agricultural medicine and community health
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• v.43 no.1
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• pp.1-8
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• 2018

Objectives: This study was performed to identify the relations between the old's participation in voluntary service activities and health-related quality of life. Methods: The subjects of the study were 318 elderly people aged over 65 years. They were interviewed with the use of a questionnaire from May 1 to June 30, 2012 to collect data. To verify the data collected, this study carried out a linear regression analysis. Results: The health-related quality of life of the elderly who were participating in voluntary service activities was statistically significantly higher than that of those who were not. Conclusions: This study has meaning in that it discovered that the elderly people's participation in voluntary service activities had a positive effect on their health-related quality of life.

• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.473-479
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• 2003

The purpose of this study is to recover the CIE XYZ tristimulus values of original colors from scanner output signals, and to reproduce true colors on the monitor. The process of this study is composed of three steps; scanner characterization, chromatic adaptation transformation, and color space transformation between and sRGB. Especially, in the process of recovery, scanner stimuli were obtained accurately by dividing the non-linear photometric response curve into two parts. As the result of test to EPSON Expression 1680 scanner, the average color difference between true and recovered XYZ for 228 target colors, 22 test neutrals, and 36 test colors were 1.49, 0.97, and 1.42 $\Delta$ $E_{UV}$ *, respectively. With the transformation from illuminant D50 to illuminant D65, the input signals to sRGB monitor were predicted. Finally, it could be found that displayed colors with predicted input signals were very consistent with true colors. with true colors.

• The Journal of Engineering Geology
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• v.32 no.4
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• pp.597-610
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• 2022

Knowledge of the failure behavior of friction materials considering their intermediate principal stress is related to an understanding of situations where these materials might be used: for example, the stability of deep-seated boreholes and fault slip analysis. This study designed equipment for physically implementing true triaxial compression and used it to assess specimens of plaster, a friction material. The material's mechanical behaviors are discussed based on the results. The applicability of the 3D failure criteria are also reviewed. The tested specimens were molded cuboids of width, length, and height 52, 52, and 104 mm, respectively. A total of 24 true triaxial compression tests were performed under various combinations of 𝜎₃ and 𝜎₂ conditions. Conventional uniaxial and triaxial compression tests were employed to estimate the mechanical properties of the plaster for use as parameters for 3D failure criteria. Examining the stress-strain relations of the plaster materials showed that a large difference between the intermediate principal stress and the minimum principal stress indicated strong brittle behavior. The mechanical behavior of the plaster used here reflects the change of intermediate principal stress. Nonlinear multiple regression analysis on the test data in the principal space showed that the modified Wiebols-Cook failure criterion and the modified Lade failure criterion were the most suitable 3D failure criteria for the tested plaster.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.168-181
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• 2016

The purpose of this study was to investigate eating habits and patterns in accordance with the mental health status in Korea. Data from the fifth Korean National Health and Nutrition Examination Survey in 2010-2012 by the CDCP were used to target 19-year-olds. A total of 15,484 subjects (6,348 men and 9,500 women) were enrolled in this study. The collected data were analyzed using frequency analysis, cross-analysis, and multiple logistic regression analysis. The results revealed that men showed, with linear tendency, a decrease in stress and suicidal ideation with an increase in the number of meals. (p<.05). Women also showed, with linear tendency, that an increase in the number of meals resulted in a reduction of stress, depression, and suicidal ideation (p<.05). The stress level of women decreased by 0.667 times when they ate two meals rather than one time meal per day. If women ate three meals compared with one meal per day, stress, depression, and suicidal ideation were reduced by 0.522, 0.605, and 0.508 times, respectively (p<.05). It was found that Aa regular eating habit may have an impact on stress, depression, and suicidal ideation. Moreover, irregular meals, brought on by modern influences, could have a negative impact on mental health, leading to social and economic losses. These results suggest that we need to educate and promote awareness on proper eating habits.