• Computers and Concrete
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• v.15 no.4
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• pp.485-501
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• 2015

Cooling by the flow of water through an embedded cooling pipe has become a common and effective artificial thermal control measure for massive concrete structures. However, an extreme thermal gradient induces significant thermal stress, resulting in thermal cracking. Using a mesoscopic finite-element (FE) mesh, three-phase composites of concrete namely aggregate, mortar matrix and interfacial transition zone (ITZ) are modeled. An equivalent probabilistic model is presented for failure study of concrete by assuming that the material properties conform to the Weibull distribution law. Meanwhile, the correlation coefficient introduced by the statistical method is incorporated into the Weibull distribution formula. Subsequently, a series of numerical analyses are used for investigating the influence of the correlation coefficient on tensile strength and the failure process of concrete based on the equivalent probabilistic model. Finally, as an engineering application, damage and failure behavior of concrete cracks induced by a water-cooling pipe are analyzed in-depth by the presented model. Results show that the random distribution of concrete mechanical parameters and the temperature gradient near water-cooling pipe have a significant influence on the pattern and failure progress of temperature-induced micro-cracking in concrete.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.3
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• pp.222-235
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• 2015

The purpose of this study is to suggest guidelines for riser fatigue analysis in terms of selection of reasonable analysis method. Three analysis methods (spectral, regular wave, rain-flow counting) are introduced and compared. As the riser systems give non-linear response, the time-domain analysis method is more preferred than frequency-domain analysis method. The spectral fatigue analysis method, however, is still useful for identifying fatigue prone areas. Once stress RAO is established, fatigue damage can be calculated very quickly. The regular wave method and the rain-flow counting method are more time consuming but give more exact results compare to spectral method. In case of regular wave method, a set of regular waves which represent random sea states is considered for dynamic analysis. The rain-flow counting method is the most intuitive and exact method because it refers time history stresses containing most of non-linear effects of the riser system. However, it is not common for early design stage to use rain-flow counting method because of its high cost. In this study, it was confirmed that the regular wave method is the most cost effective way in specific cases. However, if the system is highly non-linear, it seems that the regular wave method gives less accurate results than rain-flow counting method. Therefore, it is imperative that the engineers select appropriate analysis method based on design stage and given engineering period. This paper also discusses the theoretical background of each calculation method and hydrodynamic aspects of marine riser systems. A steel catenary riser (SCR) line on FPSO was considered and marine dynamic program (OrcaFlex) was used for static and dynamic analysis.

• Journal of radiological science and technology
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• v.32 no.1
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• pp.69-78
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• 2009

The cardiovascular disease has been known as a common cause of death for a long time in the west. The eating habits of Asia, including Korea, have changed recently, so that this disease is also a problem in Asia now. Annual Report on the Cause of Death Statistics from 1996 to 2006 reported that the cardiovascular disease would become the number one cause of death in the next $5{\sim}10$ years. Therefore we realize that more accurate examination is required. The aim of this study was to investigate the accuracy of Calcium-scoring CT and the relationship between risk factor and quantitative scores of Calcium-scoring CT. Through this study we expect that the national public health will be improved. Seventy patients with chest pain were chosen at random. The patients were undergone both coronary CT antigraphy and Calcium - scoring CT at G hospital in Incheon from February 1 to June 30, 2008. The result of the Calcium-scoring CT showed its usefulness for Ischemic cardiovascular disease, with an accuracy similar to that of exercise/pharmacologic stress or ECG when it is difficult for a patient to exercise due to joint problems, aging or for other reasons.

• Journal of Korean Public Health Nursing
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• v.13 no.1
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• pp.97-113
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• 1999

To investigate the actual condition of the adult-smoking in Chinan County. I used self-reporting questionnaires among 923 residents living in nine districts selected at random among the sites of eleven eup-myons from December 28. 1998 to January 6. 1999. collected data and analyized using SPSS. The smoking rate of adults in Chinan County was $36.9\%$. There was a significant difference in smoking rate according to the age. gender, education and job among general characteristics. The smoking rate in group of above 40s was about $40\%$ and that of the male took $55.5\%$ which was higher than that of female and the smoking rate of the people having high-school education was the highest$(46.2\%)$. With regard to the career. the smoking rate of the farmers ranked first$(46.1\%)$. Therefore anti-smoking business for smokers should be focused on above 40 years old, males. people having high school education and farmers. As the result of the survey of smoking habits of 340 people who smoke currently, the average smoking begining age was 21.8 and $81.5\%$ among them was between 16-25 years old. $4.4\%$ was under 15. during around the elementary school. Most motives to smoke were as followed; curiosity or taste$(33.6\%)$, relief of stress $(31.2\%)$, peer presure$(26.5\%)$ And considering the amount of the cigarette which is smoked per day, the case which is less than a pack of cigarettes was highest as $75.5\%$ and the people who smoke over one pack of cigarettes took $24.5\%$. As for the kind of tobacco which is smoked, how to smoke and the desire for the smoking, most case was toxin was moderate$(47.8\%)$ or mild$(46.9\%)$. shallowly$(49.0\%)$ or deeply$(46.3\%)$ and under stress$(33.4\%)$. after meals$(27.8\%)$, during drink$(15.7\%)$ and so on. The highest point marked among the factors of smoking motives was 'the reduce of negative emotion' $(3.27\pm1.00)$. followed by 'uncomfortable habits' $(2.87\pm1.02)$, 'addiction' $(2.84\pm1.06)$. 'habit' $(2.74\pm1.12)$. 'pleasure' $(2.70\pm1.04)$. 'stimulus' $(2.59\pm.90)$, 'sensation-exercise satisfaction' $(2.42\pm.97)$. Smokers smoke to reduce the negative emotions when angry in most common case. depressed. anxious. uncomfortable. lone. ashamed or embarrased. and intend to solve the certain problem. etc. Other motives are uncomfortable habit. addiction. habit. pleasure and the pursuit of stimulus. The level of nicotine dependence of adults m Chinan County was 10.57 which amount to 'high' wholly. As the resulf of the level of nicotine dependence score. the people who are low in the level of nicotine was $33.5\%$. the people who are high was $48.2\%$. very high was $18.4\%$. The approach for anti-smoking for smokers should be conducted differently according to the level of the nicotine. For the people who are in low level of nicotin dependence the prohibition of the smoking should be guided through the approach to foster strong will. for those who are in 'high' by acquiring proper method for the prohibition of smoking. and for those who are 'very high' the anti-smoking should be induced by providing proper program because of the possibility of the suffer from abstinence syndrome. The difference of the level of nicotine with the general characteristics of the objects had not statistically significant difference. The difference of the level of nicotine dependence accompanied by smoking habit had statistically significant difference according to the amount of smoke, the kind of tobacos. smoke inhale habit. In other words, the group of heavy smokers had higher level of the nicotine dependence than that of the light smokers relatively and the group which smoke strong taboaco has higher level of nicotine than that of which smoke mild or moderate. And the group of smokers who smoke deeply has higher level of nicotine than that who smoke shallowly or nonswallow. Aa a result of the analysis of the correlation between smoking motive factors and the level of nicotine, there was the indication that people who smoke for the decrease of the negative emotion. habit, pleasure. stimulus. sensation-exercise satisfaction had high level of the nicotine dependence. As the result of the anti-smoking will of smokers. $65.0\%$ of them had prohibition of smoking will. $29.3\%$ had no will to quit smoke. The most important reason for anti-smoking was health. $67.9\%$ had experience to try to quit smoke and the biggest reason to fail to quit smoking was the lack of the will power to keep anti-smoking. $52.8\%$ of them were advised to stop smoking from their spouses or children. only $2.8\%$ were by medical. The people who have the opinion to need anti-smoking education were $69.6\%$. Therefore when the business for the hygine of the mouth for adult is set. it should be centered on the people who have intention of prohibition of the smoking and help to quit smoking by way of other affirmative counter-program not smoking under stress.