• 한국물환경학회지
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• 제24권1호
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• pp.99-106
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• 2008

With globally increasing interests in climate-soil-vegetation system, a new stochastic model of soil water and plant water stress is derived for better understanding of the soil water and plant water stress dynamics and their role in water-controlled ecosystem. The steady-state assumption is used for simplifying the equations. The derived model is simple yet realistic that it can account for the essential features of the system. The model represents the general characteristics of rainfall, soil, and vegetation; i.e. the soil moisture constitutes the decrease form of the steady-state and the plant water stress becomes increasing with the steady state when the rainfall is decreased. With this model, further deep study for the effects of soil water and plant water stress on the system will be accomplished.

• 한국대기환경학회지
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• 제20권1호
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• pp.47-58
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• 2004

The $textsc{k}$-$\varepsilon$ algebraic stress model (KEASM) was applied to atmospheric dispersion simulation using the Lagrangian particle dispersion model and was compared with the most popular turbulence closure model in the field of atmospheric simulation, the Mellor-Yamada (MY) model. KEASM has been rarely applied to atmospheric simulation, but it includes the pressure redistribution effect of buoyancy due to heat and momentum fluxes. On the other hand, such effect is excluded from MY model. In the simulation study, the difference in the two turbulence models was reflected to both the turbulent velocity and the Lagrangian time scale. There was little difference in the vertical diffusion coefficient $\sigma$$_{z}$. However, the horizontal diffusion coefficient or calculated by KEASM was larger than that by MY model, coincided with the Pasquill-Gifford (PG) chart. The applicability of KEASM to atmospheric simulations was demonstrated by the simulations.s.

• 한국직업건강간호학회지
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• 제24권2호
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• pp.103-113
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• 2015

Purpose: This study was to construct a structural equational model for explaining and predicting job stress of intensive care unit (ICU) nurses based on the Integrated model of stress of Ivancevich and Matteson (1980). Methods: The subjects of this study were 220 nurses at ICU. The data were collected from August 5 to 30, 2013 through self-reporting questionnaire survey. Results: According to the hypothetical model of this study, perceived nursing practice environment, perceived role conflict, perceived transformational leadership and perceived self-esteem showed statistically significant effects on job stress of ICU nurses directly. Professional self-concept indirectly affect job stress of ICU nurses. In conclusion, job stress of ICU nurses was directly influenced by nursing practice environment, role conflict, transformational leadership and self-esteem. Professional self-concept of the relationships among variables did not have a direct impact on job stress. Conclusion: Based on the results of this study, it is needed to develop stress management measures and programs considering these variables in order to adequately manage job stress of ICU nurses.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권12호
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• pp.3943-3959
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• 2022

People are constantly exposed to stress and anxiety environment, which could contribute to a variety of psychological and physical health problems. Therefore, it is particularly important to identify psychological stress in time and to find a feasible and universal method of stress reduction. This research investigated the influence of different music, such as relaxation music and natural rhythm music, on stress relief based on Electroencephalogram signals. Mental arithmetic test was implemented to create a stressful environment. 23 participants performed the mental arithmetic test with and without music respectively, while their Electroencephalogram signal was recorded. The effect of music on stress relief was verified through stress test questionnaires, including Trait Anxiety Inventory (STAI-6) and Self-Stress Assessment. There was a significant change in the stress test questionnaire values with and without music according to paired t-test (p<0.01). Furthermore, a model based on Transformer for stress level classification from Electroencephalogram signal was proposed. Experimental results showed that the method of listening to relaxation music and natural rhythm music achieved the effect of reducing psychological stress and the proposed model yielded a promising accuracy in classifying the Electroencephalogram signal of mental stress.

• 대한안전경영과학회지
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• 제18권1호
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• pp.89-97
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• 2016

This current research investigated whether job stress mediates the relationship between physical environment and safety behavior of members in organization. Furthermore, we hypothesized that safety climate functions as moderator between physical environment-job stress link. In order to examine the hypotheses, 870 employees in various fields of companies were sampled. Using structural equation modeling(SEM), we conducted moderated mediation model analysis which cab elaborately test the significance of our hypotheses. The results showed that job stress mediated the link between physical environment and safety behavior of members. Moreover, the relationship between physical environment and job stress was moderated by safety climate. The implications and limitations of our study and suggestions for future research were discussed.

• 보건교육건강증진학회지
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• 제29권3호
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• pp.63-74
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• 2012

Objectives: We aim to investigate association between health behavior, interpersonal/organizational environment and job stress among government officials. Methods: Through health examination and a survey, this cross sectional study investigated 543 government officials working at Central Government Complex in Seoul, Korea. Health behaviors included alcohol drinking, smoking, moderate exercise and food frequency. Interpersonal environment was measured by health behavior practices of significant others and social support for health promotion. And the measures of organizational environment included facilities for exercise, health related norms and health supportive organizational systems. Job stress was assessed by short version of Korean Occupational Stress Scale(KOSS). Results: The level of job stress among female officials was higher than that of male officials. Multivariate logistic model suggested that higher job stress in male officials was significantly associated with lower position(OR=0.267, p<.01) less grain intake(OR=0.642, p<.05), lower level of social support(OR=0.810, p<.01) and abdominal obesity(OR=2.407, p<.05). On the contrary, female officials' stress level was negatively associated with healthy organizational environment(OR=0.725, p<.05). Conclusions: It is suggested that addressing job stress require tailoring intervention by gender characteristics and integration of interpersonal and organizational level approaches.

• 한국물환경학회지
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• 제25권4호
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• pp.507-514
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• 2009

In this study, a dynamic modeling scheme is presented to describe the probabilistic structure of soil water and plant water stress index under stochastic precipitation conditions. The proposed model has the form of the Fokker-Planck equation, and its applicability as a model for the probabilistic evolution of the soil water and plant water stress index is investigated under a climate change scenario. The simulation results of soil water confirm that the proposed soil water model can properly reproduce the observations and show that the soil water behaves with consistent cycle based on the precipitation pattern. The simulation results of plant water stress index show two different PDF patterns according to the precipitation. The simple impact assessment of climate change to soil water and plant water stress is discussed with Korean Meteorological Administration regional climate model.

• 한국농공학회논문집
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• 제60권4호
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• pp.113-122
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• 2018

Thermal stress of pigs causes decreased feed consumption and weight gain rate, immunosuppression, reproductive disorders, and increased mortality. The concept of the temperature-humidity index (THI) has been widely used to evaluate the degree of thermal stress of pigs. However, use of this concept is strongly restricted for animals living in the enclosed facilities. In this study, Building Energy Simulation (BES) technique was used to realize the energy flow among outside weather conditions, building materials, and animals. Especially, mechanisms of sensible and latent heat generation from pigs according to surrounding air temperature and their weight were designed to accurately evaluate the THI values inside the pig house. The THI values computed by the BES model were compared to those calculated by method of the report (NIAS, 2016), the model of this study predicted the start date of heat stress about 9~76 days earlier compared to the NIAS model. Results of the BES model also showed higher frequencies of the THI above the THI threshold for pigs, indicating that conventional model has a possibility of underestimating the degree of heat stress of pigs.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권11호
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• pp.3099-3120
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• 2023

The present fast-moving era brings a serious stress issue that affects elders and youngsters. Everyone has undergone stress factors at least once in their lifetime. Stress is more among youngsters as they are new to the working environment. whereas the stress factors for elders affect the individual and overall performance in an organization. Electroencephalogram (EEG) based stress level classification is one of the widely used methodologies for stress detection. However, the signal processing methods evolved so far have limitations as most of the stress classification models compute the stress level in a predefined environment to detect individual stress factors. Specifically, machine learning based stress classification models requires additional algorithm for feature extraction which increases the computation cost. Also due to the limited feature learning characteristics of machine learning algorithms, the classification performance reduces and inaccurate sometimes. It is evident from numerous research works that deep learning models outperforms machine learning techniques. Thus, to classify all the emotions based on stress level in this research work a hybrid deep learning algorithm is presented. Compared to conventional deep learning models, hybrid models outperforms in feature handing. Better feature extraction and selection can be made through deep learning models. Adding machine learning classifiers in deep learning architecture will enhance the classification performances. Thus, a hybrid convolutional neural network model was presented which extracts the features using CNN and classifies them through machine learning support vector machine. Simulation analysis of benchmark datasets demonstrates the proposed model performances. Finally, existing methods are comparatively analyzed to demonstrate the better performance of the proposed model as a result of the proposed hybrid combination.

• Water Engineering Research
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• 제6권2호
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• pp.49-61
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• 2005

This paper presents the numerical study to examine characteristics of fluid flow and solute transport in a rough fracture subject to effective normal stresses. The aperture distribution is generated by using the self-affine fractal model. In order to represent a nonlinear relationship between the supported normal stress and the fracture aperture, we combine a simple mechanical model with the local flow model. The solute transport is simulated using the random walk particle following algorithm. Results of numerical simulations show that the flow is significantly affected by the geometry of aperture distribution varying with the effective normal stress level while it is slightly affected by the fractal dimension that determines the degree of the fracture surface roughness. However, solute transport is influenced by the effective normal stress as well as the fracture surface roughness.