• Journal of Korea Water Resources Association
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• v.43 no.1
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• pp.81-94
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• 2010

Input variable selection is one of the various techniques for improving the performance of artificial neural network. In this study, mutual information is applied for input variable selection technique instead of correlation coefficient that is widely used. Among 152 variables of RDAPS (Regional Data Assimilation and Prediction System) output results, input variables for artificial neural network are chosen by computing mutual information between rainfall records and RDAPS' variables. At first the rainfall forecast variable of RDAPS result, namely APCP, is included as input variable and the other input variables are selected according to the rank of mutual information and correlation coefficient. The input variables using mutual information are usually those variables about wind velocity such as D300, U925, etc. Several statistical error estimates show that the result from mutual information is generally more accurate than those from the previous research and correlation coefficient. In addition, the artificial neural network using input variables computed by mutual information can effectively reduce the relative errors corresponding to the high rainfall events.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.36 no.1
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• pp.3-14
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• 2020

Dormitories of Korean university are planned to pursue qualitative growth after a period of quantitative growth in the 1970s. However, since the 1990s, the physical plan for qualitative growth has not changed significantly and the effects of these changes on dormitory residents has not been verified. The purpose of this study is to identify the environmental factors influencing dormitory life adaptation and to provide a basis for qualitative growth of university dormitories to help dormitory residents adapt to the environment. The research was conducted in three stages. First, the elements of the residential environment of the dormitory complex, which is an independent variable, were derived. The dormitory life adaptation scale was developed to measure the dependent variable. Secondly, a questionnaire survey was conducted to obtain the environmental factors of current dormitory and previous residence and three elements of dormitory life adaptation; 'acceptance of change', 'familiarity', and 'anxiety'. Third, statistical analysis was conducted to determine whether each factor influenced dormitory life adaptation.

• Smart Structures and Systems
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• v.20 no.1
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• pp.23-33
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• 2017

Variable Curvature Friction Pendulum (VCFP) bearing is one of the alternatives to control excessive induced responses of isolated structures subjected to near-fault ground motions. The curvature of sliding surface in this isolator is varying with displacement and its function is non-spherical. Selecting the most appropriate function for the sliding surface depends on the design objectives and ground motion characteristics. To date, few polynomial functions have been experimentally tested for VCFP however it needs comprehensive parametric study to find out which one provides the most effective behavior. Herein, seismic performance of the isolated structure mounted on VCFP is investigated with two different polynomial functions of the sliding surface (Order 4 and 6). By variation of the constants in these functions through changing design parameters, 120 cases of isolators are evaluated and the most proper function is explored to minimize floor acceleration and/or isolator displacement under different hazard levels. Beside representing the desire sliding surface with adaptive behavior, it was shown that the polynomial function with order 6 has least possible floor acceleration under seven near-field ground motions in different levels.

• Culinary science and hospitality research
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• v.12 no.2 s.29
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• pp.1-17
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• 2006

This study is to develop a viable measurement tool of crowdedness in restaurants. First, to measure customer’s awareness of crowdedness related to each different environmental factor in a restaurant, 49 factors of crowdedness awareness were selected based on the previous studies and then properties of each factor affecting customer’s satisfaction for crowdedness were analyzed. To analyze effects of each factor upon the satisfaction rate, a Multiple Regression Analysis was conducted with the crowdedness awareness as an independent variable and satisfaction of crowdedness as a dependent variable. The results showed that when an analysis of the environmental factors in the crowdedness awareness was conducted in an effort to develop a measurement tool of crowdedness awareness in restaurants, that would be fit for the domestic food service market, based upon 49 factors of restaurant environment. Focusing on expectation and satisfaction rate, it was found that rating the satisfaction level would be a much more effective tool to measure crowdedness awareness because satisfaction rate appeared to be more closely related to the awareness than the results obtained from the Multiple Regression Analysis with a difference between expectation and satisfaction scores as an independent variable.

• Journal of the Korean Society of Safety
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• v.32 no.3
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• pp.34-40
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• 2017

The catastrophic collapse of the in-boiler scaffolding system in the two thermal power plants occurred in March and April 2012. After site investigation and document review, it was found that the specialized scaffolding system was imported for overhaul & maintenance and that the system did not get the safety certification at the import. In this regard, this study developed & proposed an access platform and a support for the vertical tube section of the super heat as well as a variable-length platform for the horizontal tube section, satisfying the domestic certification standards. The access platform was developed to be easy to handle by the worker with a weight of about 0.069 kN, which could reduce the risk of falling accidents and workers' musculoskeletal diseases. For the variable-length platform, it is possible to cope with various changes in length between the horizontal tubes associated with the increase of rigidity in the overlapping and the elimination of the protrusion.

• Smart Structures and Systems
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• v.13 no.2
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• pp.319-341
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• 2014

A family of smart tuned mass dampers (STMDs) with variable frequency and damping properties is analyzed under harmonic excitations and ground motions. Two types of STMDs are studied: one is realized by a semi-active independently variable stiffness (SAIVS) device and the other is realized by a pendulum with an adjustable length. Based on the feedback signal, the angle of the SAIVS device or the length of the pendulum is adjusted by using a servomotor such that the frequency of the STMD matches the dominant excitation frequency in real-time. Closed-form solutions are derived for the two types of STMDs under harmonic excitations and ground motions. Results indicate that a small damping ratio (zero damping is the best theoretically) and an appropriate mass ratio can produce significant reduction when compared to the case with no tuned mass damper. Experiments are conducted to verify the theoretical result of the smart pendulum TMD (SPTMD). Frequency tuning of the SPTMD is implemented through tracking and analyzing the signal of the excitation using a short time Fourier transformation (STFT) based control algorithm. It is found that the theoretical model can predict the structural responses well. Both the SAIVS STMD and the SPTMD can significantly attenuate the structural responses and outperform the conventional passive TMDs.

• Korean Journal of Construction Engineering and Management
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• v.24 no.6
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• pp.81-90
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• 2023

Climate change has resulted in increased frequency and intensity of heat waves, which poses a significant threat to the health and safety of construction workers, particularly those engaged in labor-intensive and heat-stress vulnerable working environments. To address this challenge, this study aimed to propose an interpretable machine learning approach for forecasting personal heat strain by considering the cumulative effect of heat exposure as a situational variable, which has not been taken into account in the existing approach. As a result, the proposed model, which incorporated the cumulative working time along with environmental and personal variables, was found to have superior forecast performance and explanatory power. Specifically, the proposed Multi-Layer Perceptron (MLP) model achieved a Mean Absolute Error (MAE) of 0.034 (℃) and an R-squared of 99.3% (0.933). Feature importance analysis revealed that the cumulative working time, as a situational variable, had the most significant impact on personal heat strain. These findings highlight the importance of systematic management of personal heat strain at construction sites by comprehensively considering the cumulative working time as a situational variable as well as environmental and personal variables. This study provided a valuable contribution to the construction industry by offering a reliable and accurate heat strain forecasting model, enhancing the health and safety of construction workers.

• Annals of Occupational and Environmental Medicine
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• v.34
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• pp.18.1-18.12
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• 2022

Background: Little attention has been paid to the relationship between perceived discrimination and self-rated health (SRH) among foreign workers in Korea. Transnational ties with the home country are known to be critical among immigrants, as they allow the maintenance of social networks and support. Nonetheless, as far as we know, no studies have examined the impact of transnational ties on SRH itself and the relationship between perceived discrimination and SRH, which the current study tries to examine. Methods: Logistic regression analyses were conducted using the 2013 Survey on Living Conditions of Foreign Workers in Korea. Adult foreign workers from different Asian countries (n = 1,370) participated in this study. The dependent variable was good SRH and the independent variable was perceived discrimination. Transnational ties with the home country, as a moderating variable, was categorized into broad (i.e., contacting family members in the home country) vs. narrow types (i.e., visiting the home country). Results: Foreign workers who perceived discrimination had a lower rate of good SRH than those who did not perceive discrimination. Broad social transnational ties moderated the relationship between perceived discrimination and SRH; narrow social transnational ties did not. Conclusions: In line with previous studies, an association was found between perceived discrimination and SRH. Broad social transnational ties can be a good source of social support and buffer against the distress of perceived discrimination.

• Journal of the Korean Home Economics Association
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• v.36 no.5
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• pp.47-58
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• 1998

The purposes of this study was to examine the effects of demographics, environmental attitude, environmental behavior, exposure to environmental information, and motives of clothing disposition on clothing disposal behavior. Data were obtained from questionnaires filled out by 217 women in Taegu and were analyzed by utilizing factor analysis, correlation analysis, and stepwise regression analysis. The results indicated that clothing disposal behavior was influenced by predicted variables such as education, exposure to environmental information, environmental attitude, and environmental behavior. Among predicted variables, the environmental attitude was the most important variable affecting clothing disposal behaivor. However, the proportion of variation in clothing disposal behavior that was explained by predicted variables was relatively low.

• Journal of Environmental Impact Assessment
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• v.32 no.4
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• pp.203-213
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• 2023

The AERMOD model was the most used, accounting for 89.0%, based on the analysis of the environmental impact assessment reports published in the Environmental Impact Assessment Information Support System (EIASS) between 2021 and 2022. The mismatch of versions between AERMET and AERMOD was found to be 25.3%. There was the operational time discrepancy of 50.6% from industrial complexes, urban development projects between used in the model and applied in estimating pollutant emissions. The results of applying various versions of the AERMET and AERMOD models to both area sources and point sources in both simple and complex terrain in the Gunsan area showed similar values after AERMOD version 12 (15181). Emissions are assessed as 24-hour operation, and the predicted concentration in both simple and complex terrain when using the variable emission coefficient option that applies an 8-hour daytime operation in the model is lowered by 37.42% ~ 74.27% for area sources and by 32.06% ~ 54.45% for point sources. Therefore, to prevent the error in using the variable emission coefficient, it is required to clearly present the emission calculation process and provide a detailed explanation of the composition of modeling input data in the environmental impact assessment reports. Also, thorough reviews by special institutions are essential.