• Structural Engineering and Mechanics
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• v.44 no.4
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• pp.417-429
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• 2012

Taking the superficial temperature increment as the major fatigue damage indicator, the infrared thermography was used to predict fatigue parameters (fatigue strength and S-N curve) of welded joints subjected to fatigue loading with a high mean stress, showing good predictions. The fatigue damage status, related to safety evaluation, was tightly correlated with the temperature field evolution of the hot-spot zone on the specimen surface. An energetic damage model, based on the energy accumulation, was developed to evaluate the residual fatigue life of the welded specimens undergoing cyclic loading, and a good agreement was presented. It is concluded that the infrared thermography can not only well predict the fatigue behavior of welded joints, but also can play an important role in health detection of structures subjected to mechanical loading.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.480-485
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• 2005

This paper reviews the literature on safety culture focusing particularly on research carried out from 1998 onwards. The term 'safety culture' is clarified as it is typically applied to organizations, to safety and particularly to construction safety. Some clarifications in terms of levels of aggregation, positive safety culture and safety performance are provided by presenting appropriate empirical evidences and their theoretical developments. Safety culture is a subset of organizational culture that is thought to influence employees' attitudes and behavior in relation to an organization's ongoing health and safety performance. Implications for future research in the area are addressed, as safety culture has in recent years become the focus of much attention in all industries, and in the construction industry in particular.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.246-252
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• 2020

This study used the raw data of the 15th (2019) Korean Youth Health Risk Behavior Survey to investigate the risk factors of the health-risk behaviors of Korean multicultural adolescents on the subjective oral symptoms. The scope of the multicultural family was limited to children of immigrant women's families married to Korean men and immigrant male families married to Korean women, and 572 were selected as the final study subjects. The sociodemographic variables were surveyed as gender, grade, economic level, and school performance. The health risk behaviors included drinking, smoking, medication, stress, sleep satisfaction, suicidal thoughts, depression, and brushing before bedtime. The oral symptoms examined were toothache, gum pain, and halitosis. As a result, toothache was related to drinking, toothbrushing before sleep, stress, sleep satisfaction, suicidal thoughts, and depression. Gum pain was associated with drug use, sleep satisfaction, suicidal thoughts, and depression. Halitosis was associated with medication, brushing before sleep, stress, suicidal thoughts, and depression. In terms of health risk factors, drinking, stress, and sleep satisfaction were risk factors for toothache. Smoking, sleep satisfaction, and suicidal thoughts were risk factors for gum pain. The presence of toothbrushing and stress were risk factors for halitosis. In conclusion, a policy system is needed to support oral health education programs nationally at times, such as after-school activities or club activities, to promote oral health for teenagers.

• Journal of Korean society of Dental Hygiene
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• v.12 no.4
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• pp.759-770
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• 2012

Objectives : The purpose of this study was to examine the awareness of implant wearers about periodontal diseases and implant management, which were closely linked to implant durability, in an effort to obtain information on the right directions for oral health education related to implant self-care and specialized care. Methods : The subjects in this study were 217 patients who wore implant and visited 14 different dental hospitals and clinics in the metropolitan area. After a questioaire survey was conducted and collected data were analyed by the statistical package SPSS 18.0. Results : As for the awareness of the subjects on the regeneration of alveolar ridge by general characteristics, there were statistically significant intergroup gaps according to the number of possessed implant, implant satisfaction and subjective gingival health status(p<0.05). Regarding their awareness of implant durability by general characteristics, there were statistically significant gaps according to the number of possessed implant and oral health education experience(p<0.05). Concerning their awareness of the cycle of regular implant checkup by general characteristics, there were statistically significant gaps according to occupation, subjective gingival health status and oral health education experience(p<0.05). Conclusions : The above-mentioned findings suggest that in order to ensure the long-term safe maintenance of implant, the way of looking at periodontal diseases and implant management should be changed. Specifically, more intensive oral health education should be provided for implant wearers to be aware of the importance of self-care and specialized care to change their oral health behavior, and clinical dental hygienists should improve their role performance to make it happen.

• Journal of the Korean Society of School Health
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• v.29 no.2
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• pp.90-97
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• 2016

Purpose: The purpose of this study was to investigate the relationship between sleep timing and depressive mood in Korean adolescents. Methods: The study analyzed the data from the 2007~2015 Korea Youth Risk Behavior Web-based Survey. A total of 541,693 students in grades 7~12 were included in the final analysis. Multivariable logistic regression was used to examine their sleep timing and depressive mood, adjusted for sex, grade, region, socioeconomic status, academic performance, alcohol, smoking and physical activity. Sleep duration and sleep quality were also included in our model to identify whether or not the effect of sleep timing on depression is mediated by sleep duration or sleep quality. Results: The prevalence of depressive mood was 32.7% and the mean sleep timing was 12:13 AM. After adjustment for eligible covariates, the association between sleep timing and depressive mood showed a J-shaped curve. Adolescents who slept at 8 pm~10 pm were 39% more likely to be depressive (OR = 1.39, 95% CI 1.30~1.40) and at 3 am~ 4 am were 67% more likely to be depressive (OR=1.67, 95% CI 1.64~1.70) than adolescents who slept at 11 pm~12 am. These associations persisted after being adjusted for sleep duration and sleep quality. Conclusion: Sleep timing was related to depression in adolescents, independent of sleep duration and sleep quality. It appears that there is a certain sleep timing beneficial to mental health of adolescents.

• The Journal of the Korea Contents Association
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• v.20 no.7
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• pp.118-126
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• 2020

The purpose of the study is to analyze the relationship between the warning picture on a cigarette pack and non-smoking attempt, which is expected to contribute to the negative perception of smoking as a research subject about smoking adolescents. An online survey data of the Youth Health Behavior in 2018 has been used, and 3,722 adolescents who are currently smokers were selected for the study. For the measurement of variables, demographic sociology, health-related, and smoking-related factors have been revised, and multivariate binomial logistic regression analysis has been performed. The perception rate of cigarette warning pictures among adolescents who smoke currently is 84.7%, and among them, the attempt rate to quit smoking is 72.8%. As a result of the multivariate binomial logistic regression analysis, there is a meaningful relationship between adolescent smokers' attempts to quit smoking and whether they perceived cigarette pack warning pictures, and school grade year, academic performance, stress perception, and ease of purchasing cigarettes have been also expressed as meaningful variables. To be based on the result, it is necessary to manufacture to design a cigarette pack warning picture that can be easily recognized by smoking adolescents in the future.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.4
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• pp.1-8
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• 2016

Recently, buildings tend to be large size, complex shape and functional. As the size of buildings is becoming massive, the need for structural health monitoring(SHM) technique is ever-increasing. Various SHM techniques have been studied for buildings which have different dynamic characteristics and are influenced by various external loads. Generally, the visual inspection and non-destructive test for an accessible point of structures are performed by experts. But nowadays, the system is required which is online measurement and detect risk elements automatically without blind spots on structures. In this study, in order to consider the response of non-linear structures, proposed a signal feature extraction and the adaptive threshold setting algorithm utilized to determine the abnormal behavior by using statistical methods such as control chart, root mean square deviation, generalized extremely distribution. And the performance of that was validated by using the acceleration response of structures during earthquakes measuring system of forced vibration tests and actual operation.

• Journal of Korean society of Dental Hygiene
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• v.19 no.2
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• pp.287-295
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• 2019

Objectives: The purpose of this study was to investigate the factors affecting subjective oral symptoms according to the gender of youth from multi-cultural families in Korea using data from the 14th (2018) Korean Youth Health Behavior Survey. Methods: The independent variables used in this study consisted of gender and sweet drink intake. The dependent variable was experience of subjective oral symptoms. Compensation variables consisted of general characteristics of school type, academic performance, economic status, drinking status, smoking status, and number of tooth brushings day before. The subjects of the study were 835 children of multi-cultural families whose parents were foreigners. All statistical analyses were performed by complex samples cross-tabulation analysis and complex samples logistic regression analysis. Statistical analysis was performed using the PASW statistical package 21.0 (Statistical Packages for Social Science Inc., Chicago, IL, USA). A significance level of 0.05 was used for statistical significance. Results: The composite sample logistic regression analysis showed that there was a statistically significant difference between gender and intake of sweet drinks in experience of subjective oral symptoms. Conclusions: These results suggest that factors influence subjective oral symptoms in Korean multi-cultural adolescents. Therefore, I hope that they will be used as basic data for the introduction and development of a customized oral health education program for improving oral health of multi-cultural adolescents.

• Composites Research
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• v.22 no.6
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• pp.1-6
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• 2009

This paper presents an experimental study on the piezoresistive behavior of nanocomposite strain sensors subjected to various loading modes and their capability to detect structural deformations and damages. The electrically conductive nanocomposites were fabricated in the form of a film using various types of thermoplastic polymers and multi-walled carbon nanotubes (MWNTs) at various loadings. In this study, the nanocomposite strain sensors were bonded to a substrate and subjected to tension, flexure, or compression. In tension and flexure, the resistivity change showed dependence on measurement direction, indicating that the sensors can be used for multi-directional strain sensing. In addition, the sensors exhibited a decreasing behavior in resistivity as the compressive load was applied, suggesting that they can be used for pressure sensing. This study demonstrates that the nanocomposite strain sensors can provide a pathway to affordable, effective, and versatile structural health monitoring.

• Journal of Korean society of Dental Hygiene
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• v.13 no.2
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• pp.261-269
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• 2013

Objectives : This research examined the Patient Hygiene Performance(PHP) index according to smoking and tooth brushing behavior, in order to analyze how they influence the oral hygiene. Methods : This research used PHP index and the structured questionnaire. The subjects were 203 men in their 20's who visited K university's dental hygiene department for oral prophylaxis from March to July of 2012. For data analysis SPSS WIN 12.0 was used. Results : 1. The average PHP index of all experimented subjects was 2.66, a very poor level. The PHP index according to general characteristics, smoking, drinking, and exercise showed statistical significance(p<0.05). 2. PHP index decreased with more frequencies and longer durations of toothbrushing(p<0.05). 3. The PHP index of smokers is higher than that of non-smokers. In the case of non-smokers, the frequency, method, and duration of tooth brushing had a statistical significance(p<0.05). 4. The PHP index of smokers who smoke less than or equal to ten cigarettes is 2.53 and smokers who smoked more than 10 cigarettes is 3.10. 5. The results of multiple regression analysis showed that smoking increased the PHP index, while the increase in tooth brushing frequency and the up and down tooth brushing method decreased the PHP index. All the coefficients were statistically significant (p<0.05). Conclusions : In order to increase Patient Hygiene Performance(PHP) index. there must be a decrease in smoking rate while people increase their tooth brushing frequency and use a proper tooth brushing method.