• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.2
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• pp.128-136
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• 2014

It is known that the best way to recycle fly ash is to use in concrete. It is impossible to bury in the ground this fly ash recently, so it is trying to use high volume fly ash concrete. Nevertheless, recent main research topics are focused in the part of material only. However, it is necessary to perform the researches about elasticity modulus, stress-strain relationship and structural behavior. Therefore, in this paper, 18 test members were manufactured with 3 test variables, namely fly ash replacement ratio 0, 35, 50%, concrete compressive strength 20, 40, 60MPa and 2 tensile steel ratio. 18 test members were tested for flexural behavior. From the test results, there were no differences between 35, 50% high volume fly ash cement concrete and ordinary concrete without fly ash (FA=0%). In order to evaluate the HVFAC flexural behavior, Analytical model was proposed and the computer program was developed. There were no differences between test results and analysis results. So, the proposed analytical model was reasonable.

• Journal of Preventive Medicine and Public Health
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• v.40 no.6
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• pp.467-474
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• 2007

Objectives : Gastric cancer is the most common incident cancer in Korea. Although Helicobacter pylori infection is the most important risk factor for the development of gastric cancer, cigarette smoking has also been suggested to play an important role in the development of gastric cancer. The objective of this study is to evaluate the relationship between cigarette smoking and gastric cancer risk in a Korean population. Methods : The study population consisted of 13,785 subjects who had been enrolled in the Korean Multi-Center Career Cohort between 1993 and 2002. As of December 2002, 139 incident gastric cancer cases were ascertained through the Korea Central Cancer Registry and the National Death Certificate Database. Relative risks (RR) and 95% confidence intervals (CI) for gastric cancer were estimated using Cox#s proportional hazard model adjusted for age, education, alcohol drinking status and history of gastritis or ulcer. Results : Significant dose-response relationships were observed between the duration of smoking and the risk of gastric cancer among the male subjects in comparison to non-smokers: men who smoked for 20-39 years had a 2.09-fold (95% CI 1.00-4.38) increase, and those who smoked for more than 40 years had a 3.13-fold (95% CI 1.59-6.17) increase in the risk of gastric cancer ($P_{trend}<0.01$). Conclusions : This study suggests that a longer duration of cigarette smoking may increase the risk of gastric cancer development in a dose-response manner in Korean men. The association between smoking and gastric cancer risk in women should be verified in future studies with a larger number of cases.

• Korean Journal of Ecology and Environment
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• v.48 no.1
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• pp.1-11
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• 2015

Abstract The purpose of study is to identify the relationship between stable isotope composition of reed stems in coastal and understand the structure of the fish community in 10 lagoons along the East Sea. The fish species composition (particularly, anadromous fish species) and relative abundance of trophic guilds was influenced by difference of geomorphic characteristics among lagoons. Reed stems ${\delta}^{13}C$ and ${\delta}^{15}N$ values ranged from $-28.40{\pm}0.11$‰ to $-26.87{\pm}0.25$‰ and $-1.09{\pm}1.45$‰ to $12.08{\pm}0.53$‰, respectively. The differences in reed stem ${\delta}^{15}N$ values might be associated with anthropogenic landuse and the geomorphic characteristics among lagoons. These results provide useful information to improve the conservation of fish habitats (biodiversity), preserve lagoon habitats and contribute to watershed management effect against anthropogenic pollution from watershed in these lagoon ecosystems.

• Journal of The Korean Association For Science Education
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• v.20 no.4
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• pp.680-692
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• 2000

An assessment instrument dealing with secondary students' views on the nature of science was developed in this study. The features in aspects of the nature of science are generally accepted as characterizing the scientific enterprise and we have focused on are: 1) the purposes of the scientific enterprise, 2) the nature of scientific enquiry, 3) the nature and status of scientific knowledge, and 4) the nature and functioning of the scientific community. The questionnaire is made of three sections; that is, "Scientific Question", "Experiment", and "Belief". The Scientific Questions probe was designed to examine the ways in which learners mark out science as a particular domain, and particularly the types of questions that they think are open to scientific investigation. The Experiment probe was designed to throw light on the ways in which learners may think about theories and their relationship to evidence in a range of contexts. A related aim concerns the sorts of activities that learners consider to be experiments, and their reasons for this. The Belief probe was designed to see whether students are able to articulate the grounds for their acceptance of a proposition and, if they are, to explore the nature of these grounds. The reliability of the instrument developed in this study was found to be 0.86.

• Journal of Digital Convergence
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• v.15 no.1
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• pp.23-34
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• 2017

This study investigated relative explanation of social support, ego-resiliency and stress coping strategies to help adaptive coping style of school-dropout adolescents under stress situation. To this end, 101 school-dropout adolescents were surveyed by visiting and requesting the outofschool youth supporting project, youth detention center, and adolescent protective and treatment facilities in Daejeon, Cheongnam, and Chungbuk. As analysis methods, descriptive statistical analysis, pearson's correlation, and hierarchical analysis were conducted and the research results are as follows. First, stress coping strategies showed positive relationship with social support and ego-resiliency. Second, a variable that showed greater explanation power for stress coping strategies was the environmental variable, the social support. Third, it was identified that there was greater explanation power when the environmental variable, the social support, and the personal variable, the ego-resiliency, were put in at the same time for stress coping strategies. According to the result, this study implies that schools, community, national policy effort and systemetic approach are required as well as improvement of personal coping capabilities in order to overcome difficulties school-dropout adolescents face.

• Journal of dental hygiene science
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• v.16 no.5
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• pp.339-348
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• 2016

We investigated the gender-specific association between average volume of alcohol consumption, binge drinking, and periodontitis using representative nationwide data. In total, we included 3,549 men and 4,810 women, aged 19 years and older, who participated in the sixth Korea National Health and Nutrition Examination Survey performed in 2013~2014. According to the average volume of alcohol consumption, study participants were grouped as follows: mild drinkers (0.1~2.0 drinks/day in men and 0.1~1.0 drink/day in women), moderate drinkers (2.1~4.0 drinks/day in men and 1.1~2.0 drinks/day in women), and heavy drinkers (>4.0 drinks/day in men and >2.0 drinks/day in women). Additionally, binge drinking was categorized as never (no binge drinking), rarely (<1 time/month), occasionally (1 time/month), frequently (1 time/week), and always (almost every day/week). Periodontitis was defined as a community periodontal index equal to code 3 or greater. In men, after controlling for covariates, the association between average volume of alcohol consumption and periodontitis showed a J-shaped curve; the risk of periodontitis was significantly higher in moderate drinkers (odds ratio [OR], 1.25; 95% confidence interval [CI], 1.01~1.56) and heavy drinkers (OR, 1.39; 95% CI, 1.04~1.87) than in mild drinkers. In contrast, no significant association between average volume of alcohol consumption and periodontitis was observed in women. In a fully adjusted analysis, which used 'never binge drinking' as a reference, a significant dose-response relationship between binge drinking and periodontitis was observed only in men: rarely (OR, 1.64; 95% CI, 1.16~2.34), occasionally (OR, 1.51; 95% CI, 1.05~2.16), frequently (OR, 1.58; 95% CI, 1.07~2.33), and always (OR, 2.56; 95% CI, 1.56~4.22) (p for trend=0.005). In conclusion, unhealthy drinking patterns such as moderate or heavy alcohol consumption and binge drinking were significantly associated with periodontitis in men but not in women.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.10
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• pp.1090-1097
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• 2006

The anoxic activated sludge process was applied to the treatment of industrial box-mill wastewater, which exhibited the high removal efficiencies of $90{\sim}94%$$ TCOD_{Mn}$ and $58{\sim}81%$ Color. For the design of industrial anoxic activated sludge process, Monod bio-kinetic coefficients of box-mill wastewater were estimated as follows: $K_{max}$(maximum specific substrate removal rate)=0.52 $day^{-1}$, $K_s$(half saturation constant)=314 mg/L, $K_d$(decay coefficient)=0.274 $day^{-1}$, y(microbial yield coefficient)=0.908 mg/mg, and ${\mu}_{max}$(maximum specific growth rate)=0.472 $day^{-1}$. Space loading factors for the design analysis were practically determined as the values of F/M ratio=$0.043{\sim}0.07$ kg-$TCOD_{Mn}$/kg-SS-day, BOD space loading=$0.18{\sim}0.3$ kg-$TCOD_{Mn}/m^3-day$, and ${\theta}_x=6.8{\sim}26.4$ day when considering the relationship of these loading factors with growth dynamics of microorganisms, the F/M ratio that is inversely proportional to ${\theta}_x$ should be equivalent to ${\mu}_{max}$ in units, but exhibited the significant difference between theses two values. Therefore, it is considered that high safety factors are requested in the design of anoxic activated sludge process that is based on Monod bio-kinetics of microorganism.

• Journal of Distribution Science
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• v.12 no.6
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• pp.81-88
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• 2014

Purpose - Entrepreneurship promotion is emerging as an important economic growth agenda. However, in Korea, entrepreneurship has weakened because of the collapse of the venture bubbles of the 2000s and the global economic recession in 2008, which have induced the business community to choose stability over risk. The Korean government has been implementing several support projects to inspire and promote youth entrepreneurship through various means including financial assistance; however, the perpetuation rate of young entrepreneurship is still low as compared to advanced economies such as the US and EU. This case study focuses on the Youth Start-Up Business Support Program of the Small & Medium Business Corporation, and explores practical alternatives. Further, it aims to suggest managerial factors and a conceptual model for change management factors affecting the business performance creation of a startup company, based on the Small and medium Business Corporation's young venture startup fund. Research design, data, and methodology - Many studies examine the current progress and issues of startup firms, for example, a lack of systematic cultivation of entrepreneurship and startup business training, lack of commercialization funding for youth startup businesses, lack of mentoring, and inadequate infrastructure. From prior research, we address four factors, namely, personal managerial capabilities, innovative business model, sufficient cash flow, and social network, affecting startup companies' business performance. This study involved a sample survey of 200 young entrepreneurs to investigate casual relations between the four factors and business performance. A regression analysis was used to verify the hypotheses. Results - First, in relation to differences in the founder's personal characteristics, age, sales amount, and number of employees significantly impact business performance. Second, regarding the causal relation between the four factors for creating business performance, an innovative business model and social networking have supported the hypotheses, revealing that the more that a start-up founder has an innovative business model and social networking, the more the start-up firms are likely to have better performance (e.g., sales volume, employment, ROE, ROI, etc.). Although the founder's competency and sufficient cash flow have no significant relationship with business performance, the mean value was higher performance for high founder's competency and sufficient cash flow. Conclusions - This study provides basic data on policy support strategies of the Small and Medium Business Corporation, to help young entrepreneurs achieve their start-up business goals. It shows that young entrepreneurship startup firms should strive to explore ideas to satisfy customers' needs, and that changes in customer value and the continuous innovation of business model differentiation are required to actively respond to change management. Moreover, at the infant startup stage, they should activate social network programs to share information, thereby offsetting resource scarcity and managing business risk. Further, the establishment of a long-term vision and the implementation of training programs in related specific fields should be supported to strengthen founders' personal capabilities.

• Journal of the Economic Geographical Society of Korea
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• v.13 no.4
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• pp.641-662
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• 2010

Through the comparative studies on Korean and Chinese ethnobanks in the U.S., this research finds the difference in the social capital between Korean and Chinese American economy and reinterprets the social capital in overseas Chinese. In many ethnic studies, the ethnobanks in the U.S. are thought as the main drive of the economic prosperity in the ethnic communities. For the success of these ethnobanks, the relationship banking of these ethnobanks are contrasted with the arms-length banking of the mainstream U.S. banks. However there are the differences both in performance and business strategies even among different ethnobanks. Contrary to the Korean ethnic banks having much portion of business loans, Chinese ethnic banks have stressed real-estate loans in their loan portfolio. This research regards the differences of business strategies and performance of these ethnobanks as the result of the different social, cultural contexts in each ethnic community. From these finings, we can improve the understanding of the concept of social capital in overseas Chinese economy.

• Journal of dental hygiene science
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• v.16 no.1
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• pp.101-109
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• 2016

The purpose of this study was to examine the impact of the oral health behaviors and lifestyle of hypertension patients on their perceived periodontal diseases. The data of the 2013 community health survey were used, and the data of 55,632 patients who suffered from hypertension and who were at the ages of 19 and over was analyzed. The analying methods used in this study were chi-square test and multiple logistic regression analysis. Gender, age, marital status, education, economic activity, income level and subscription to private medical insurance were identified as the factors to affect the perceived periodontal disease of the hypertension patients, and lifestyle and oral health behaviors were found to have exerted a significant influence on perceived periodontal disease. As this study found that not only the socioeconomic characteristics of the hypertension patients but their oral health care and lifestyle were all correlated with perceived periodontal disease, how to promote the oral health of those who are susceptible to periodontal diseases should carefully be considered.