• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.1
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• pp.83-91
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• 2004

Nonlinear system responses of an impact system under randomly perturbed harmonic excitations are predicted in the probability domain by adopting the semi-analytical procedure previously developed. The semi-analytical procedure is obtained by solving the Fokker-Planck equation corresponding to the stochastic differential equation of the given impact system by utilizing the path-integral solution. The evolutionary joint probability density functions are generated by using the method, and the characteristics of nonlinear dynamic response behaviors of the system are examined. Noise effects on the responses are also examined. It Is found that the semi-analytical method can provides the accurate information of the responses via the joint probability functions for the impact system. It is found that the noises weaken and eventually terminate the chaos in the responses, but it is also found that the chaotic signatures reside in the presence of the external noise with relatively high intensity. The joint probability density function shows that the ensemble of the system responses are weakly stationary.

• Safety and Health at Work
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• v.11 no.1
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• pp.26-32
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• 2020

Background: Hong Kong's construction industry currently faces a manpower crisis. Blue-collar workers are a disadvantaged group and suffer higher levels of chronic diseases, for example, cancer, than the wider population. Cancer risk factors are likely to cluster together. We documented prevalence of cancer-associated lifestyle risk behaviors and their correlates among Hong Kong construction workers. Methods: Data were collected from workers at 37 railway-related construction worksites throughout Hong Kong during May 2014. Tobacco use, alcohol consumption, unbalanced nutrition intake, and physical inactivity were included in the analysis. Latent class analysis and multivariable logistic regression were performed to identify the patterns of risk behaviors related to cancer, as well as their impact factors among construction workers in Hong Kong. Results: Overall, 1,443 workers participated. Latent class analysis identified four different behavioral classes in the sample. Fully adjusted multiple logistic regression identified age, gender, years of Hong Kong residency, ethnicity, educational level, and living status differentiated behavioral classes. Conclusion: High levels of lifestyle-related cancer-risk behaviors were found in most of the Hong Kong construction workers studied. The present study contributes to understanding how cancer-related lifestyle risk behaviors cluster among construction workers and relative impact factors of risk behaviors. It is essential to tailor health behavior interventions focused on multiple risk behaviors among different groups for further enlarging the effects on cancer prevention.

• Steel and Composite Structures
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• v.12 no.3
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• pp.207-230
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• 2012

Nowadays CFRP (Carbon Fiber Reinforced Polymer) became widely used materials for the strengthening and retrofitting of structures. Many experimental and analytical studies are encountered at literature about strengthening beams by using this kind of materials against static loads and cyclic loads such as earthquake or wind loading for investigating their behavior. But authors did not found any study about strengthening of RC beams by using CFRP against low velocity impact and investigating their behavior. For these reasons an experimental study is conducted on totally ten strengthened RC beams. Impact loading is applied on to specimens by using an impact loading system that is designed by authors. Investigated parameters were concrete compression strength and drop height. Two different sets of specimens with different concrete compression strength tested under the impact loading that are applied by dropping constant weight hammer from five different heights. The acceleration arises from the impact loading is measured against time. The change of velocity, displacement and energy are calculated for all specimens. The failure modes of the specimens with normal and high concrete compression strength are observed under the loading of constant weight impact hammer that are dropped from different heights. Impact behaviors of beams are positively affected from the strengthening with CFRP. Measured accelerations, the number of drops up to failure and dissipated energy are increased. Finite element analysis that are made by using ABAQUS software is used for the simulation of experiments, and model gave compatible results with experiments.

• Steel and Composite Structures
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• v.44 no.2
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• pp.225-240
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• 2022

Local responses of steel plate-concrete composite (SC) walls under impact loads are typically evaluated using design equations available in the AISC N690s1-15. These equations enable design of impact-resistant SC walls, but some essential parts such as the effects of wall size and shear reinforcement ratio have not been addressed. Also, since they were developed for design basis events, improved equations are required for accurate prediction of the impact behaviors of SC walls for beyond design basis impact evaluation. This paper presents a numerical study to construct a robust numerical model of SC walls subjected to impact loads to reasonably predict the SC-wall impact behavior, to evaluate the findings observed from the impact tests including the effects of the key design parameters, and to assess the actual responses of full-scale SC walls. The numerical calculations are validated using intermediate-scale impact tests performed previously. The influences of the fracture energy of concrete and the conservative aspects of the current design equations are discussed carefully. Recommendations are made for design practice.

• The Journal of the Korea Contents Association
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• v.21 no.9
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• pp.790-805
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• 2021

The purpose of this study is to empirically examine the relationship between the ethical leadership of the top management of a company and the knowledge-sharing and innovative behaviors of the members of the organization in order to present a strategy that can be used to strengthen the innovative behaviors of the members. Also, by examining the moderating effect of the awareness of organizational support among the members. The findings of this study were as follows; First, the ethical leadership of the top management had a significant, positive impact on the innovative behaviors of the members of the organization. Second, the ethical leadership of the top management had a significant positive impact on the knowledge sharing among the members. Third, the sharing of knowledge among the members had a significant positive impact on innovative behaviors. Fourth, in the relationship between the ethical leadership of the top management and the innovative behaviors of the members, the sharing of knowledge among the members had a significant mediating effect. Fifth, the awareness of organizational support had a moderating effect in the relationship between the ethical leadership of the top management and the sharing of knowledge among the members.

• Structural Engineering and Mechanics
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• v.58 no.2
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• pp.199-216
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• 2016

A large number of bridges were built several decades ago, and most of which have gradually suffered serious deteriorations or damage due to the increasing traffic loads, environmental effects, and inadequate maintenance. However, very few studies were conducted to investigate the vibration behaviors of a damaged bridge under moving vehicles. In this paper, the vibration behaviors of such vehicle-bridge system are investigated in details, in which the effects of the concrete cracks and bridge surface roughness are particularly considered. Specifically, two vehicle models are introduced, i.e., a simplified four degree-of-freedoms (DOFs) vehicle model and a more complex seven DOFs vehicle model, respectively. The bridges are modeled in two types, including a single-span uniform beam and a full scale reinforced concrete high-pier bridge, respectively. The crack zone in the reinforced concrete bridge is considered by a damage function. The bridge and vehicle coupled equations are established by combining the equations of motion of both the bridge and vehicles using the displacement relationship and interaction force relationship at the contact points between the tires and bridge. The numerical simulations and verifications show that the proposed modeling method can rationally simulate the vibration behaviors of the damaged bridge under moving vehicles; the effect of cracks on the impact factors is very small and can be neglected for the bridge with none roughness, however, the effect of cracks on the impact factors is very significant and cannot be neglected for the bridge with roughness.

• Journal of Korean Medical Science
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• v.33 no.47
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• pp.302.1-303.10
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• 2018

Background: A considerable amount of research has shown that knowledge and appropriate awareness are essential for encouraging positive behaviors and promoting health. In Korea, the roles that behavioral changes play in the prevention of cancer have been an important issue since the introduction of the 10 codes for cancer prevention in 2006. Thus, the present study investigated the associations of tobacco-related knowledge with awareness and attitudes towards positive smoking-cessation behaviors. Methods: The present study analyzed data from the 2010 national questionnaire survey (n = 1,006). This study evaluated sociodemographic characteristics, smoking status, self-rated health status, health-related interests, and the accuracy of 12 tobacco-related statements to determine knowledge level and to investigate its impact on awareness and behaviors related to smoking. These parameters were examined and staged using the Precaution Adoption Process Model. Results: A higher level of tobacco-related knowledge was significantly associated with a positive attitude towards smoking cessation (5-8 correct answers: odds ratio [OR], 2.53; 95% confidence interval [CI], 1.57-4.08; ${\geq}9$ correct answers: OR, 3.90; 95% CI, 2.22-6.82; reference: ${\leq}4$ correct answers). Interestingly, among current smokers, only those who correctly responded to ${\geq}9$ of 12 tobacco-related statements were significantly associated with a positive attitude towards smoking cessation. Conclusion: This study found that having a higher level of tobacco-related knowledge had a significant impact on positive attitudes towards smoking cessation. This suggests that there is a need to disseminate appropriate knowledge to the general population to encourage positive attitudes and promote healthful behaviors in terms of smoking.

• Anxiety and mood
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• v.18 no.2
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• pp.92-100
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• 2022

Objective : The purpose of this study was to investigate the association among the fear of COVID-19, depression, risk perception, health belief, and preventive health behaviors related to COVID-19 among university students in Jeonbuk region. Methods : A cross-sectional study was conducted using an online questionnaire survey. The questionnaire included The Korean Version of Fear of COVID-19 Scale, the Korean Version of the Patient Health Questionnaire-9, and measurement tools adapted from previous studies for risk perception, health belief, and preventive health behaviors of subjects. We analyzed data using Pearson's correlation analysis, confirmatory factor analysis, and path analysis using SPSS 22 and AMOS 21. Results : The fear of COVID-19 showed significant positive influence on health belief as well as risk perception. Depression had a significant negative impact on preventive health behaviors and risk perception. Health belief showed a significant positive impact on preventive health behavior. Conclusion : Rresults revealed that the higher the level of depression was, the lower risk perception and performance of preventive health behavior were among university students in Jeonbuk region. As the level of the fear of COVID-19 became higher, the level of health belief and risk perception became higher. The higher the level of health belief was, the higher the performance level of preventive health were. Thus, it is prudent to increase the level of health belief, and lower the level of depression, in promoting preventive health behavior.

• Journal of The Korean Society of Integrative Medicine
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• v.12 no.3
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• pp.1-9
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• 2024

Purpose : The college student period is pivotal for establishing oral health management behaviors and habits that persist in adulthood; it is necessary to develop the correct behaviors. Appearance management behavior not only involves the management of an individual's appearance but also ensures a healthy quality of life. Additionally, it is related to health and oral health behavior. The purpose of this study was to determine how college students' appearance management behavior affects their oral health management behavior and to provide basic data for developing policies appropriate for the lifestyle of college students. Methods : A self-administered questionnaire was completed by 450 university students in Gyeonggi, Choung-nam, Daejeon on April 27, 2022. The survey comprised 5 questions about general characteristics, 18 about appearance management behavior, and 8 about oral health behavior. The sum of the practice questions were calculated, with higher scores indicating better oral health behavior. Results : The oral health management behavior exhibited was generally high. Notably, the health-related group (61.2 %) demonstrated significantly higher levels of clothing management (60.5 %), makeup management (56.6 %), and skincare (56.6 %) behaviors, whereas body management behavior (61.2 %) was deemed 'normal' (p<.05). The results of the stepwise multiple regression analysis examining the impact of appearance management behavior on oral health management indicated that clothing management (β=0.17) and skincare behaviors (β=0.12) were influential factors. Among these, clothing management behavior was the most influential. Conclusion : To promote oral health practices among college students, this study incorporated factors related to appearance management into oral health education to increase participation and interest. We intend our findings to serve as foundational data for developing oral health education programs that integrate elements of appearance management.

• Nutrition Research and Practice
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• v.18 no.4
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• pp.554-566
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• 2024

BACKGROUND/OBJECTIVES: Urban-rural inequities in health and mortality exist in Korea, a highly centralized developed country. The potential impact of multiple health-related lifestyle behaviors on mortality and difference between urban and rural areas is not fully understood. This study aimed to investigate the effect of high-risk health behaviors on all-cause mortality among residents living in urban and rural in Korea. SUBJECTS/METHODS: Cross-sectional analyses were conducted on 8,298 adults aged 40 yrs and older from the Korea National Health and Nutrition Examination Survey 2013-2015. High-risk behaviors were defined as having poor diet quality, current smoking, high-risk drinking, or insufficient physical activity. Mortality status was linked to the Cause of Death data followed up to December 31, 2019. The associations between all-cause mortality and high-risk behaviors were evaluated using Cox proportional hazard regression models adjusted for age, sex, education, income, and survey year. Population attributable fractions (PAFs) were calculated, and effect modification analysis was conducted. Participants were stratified by residential area (urban or rural). RESULTS: During the follow-up (median: 5.4 yrs), 313 deaths occurred. A higher proportion of rural residents than urban residents engaged in multiple high-risk behaviors (28.9% vs. 22.6%; P < 0.0001). As individual factors, a greater risk of mortality was associated with poor diet quality, current smoking, and inadequate physical activity, and these tendencies persisted in rural residents, especially for diet quality. Multiple high-risk behaviors were positively associated with a higher risk of mortality in Koreans living in urban and rural areas. PAF (95% confidence interval) was 18.5% (7.35-27.9%) and 29.8% (16.1-40.2%) in urban and rural residents, respectively. No additive or multiplicative effect of the region was observed. CONCLUSION: The higher prevalence of multiple high-risk lifestyle behaviors in rural residents may explain the higher mortality in rural areas compared to urban areas. Comprehensive public health policies to improve health-related behaviors in rural populations may be needed.