• 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.

• Journal of dental hygiene science
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• v.14 no.3
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• pp.411-416
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• 2014

The purpose of this study was to examine the effects of conscious sedation on pain and anxiety of patients in implant surgery. A total of 95 patients who underwent implant surgery were included in the study. In this study, the patient's anxiety and pain to evaluate the pre-operative Visual Analogue Scale (VAS), during-operative Pain Question (PQ), post-operative (Short-form McGill Pain Questionnaire [SF-MPQ], VAS) was used for tools such as questionnaires. The data were analyzed using the chi-squire, independent-samples t-test, multiple linear regression analysis. As a result, the pain reduction was significantly different between the sedative dental treatment and non-sedative dental treatment (p<0.05). The finding of the study multiple linear regression analysis showed that operation time, implant surgery experience, gender, age, operation form and Pain Catastrophizing Scale (PCS) with factors that affect the pain and anxiety (p<0.05). According to the results of the study, considered to be necessary to develop intervention strategies effective using the PCS when managing pain and anxiety of behavior management of this implant patient. Thus, it is advised to provide necessary practical guidelines and dental utilization behaviors on patients with conscious sedation.

• Journal of dental hygiene science
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• v.14 no.3
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• pp.371-378
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• 2014

This study aims to evaluate the influence of vitamin and mineral supplement intake, and degree of calcium and phosphorus intake on occurrence of dental caries in primary teeth. Research data was derived from the Fourth Korean National Health and Nutrition Examination Survey (KNHANES) and 1,139 Korean children of 3 to 6 years were selected as subject for this study. The dft index, nutrition factor including vitamin or mineral supplement intake and degree of intake for calcium (Ca) and phosphorus (P) were identified. Chi-square test was performed to assess the difference in socioeconomic status, oral health behavior and nutrition factor, including vitamin or mineral supplement intake and degree of intake for Ca and P. Linear regression analysis was performed to identify the relationship between the dft index and the related variables. As a result, the dft index was increased with the age. Significant differences in Ca intake was examined according to the sex, and P intake was different according to the sex in 3-year-old group. Among the 4-year-old children, the vitamin and mineral supplement takers had 1.206 less dft index than the non-takers. In conclusion, intake of Ca, P and vitamin/mineral supplement was not a pivotal factor to influence the incidence of primary teeth caries. However, significantly low dft index was observed from 4-year-old group who intake vitamin or mineral.

• Journal of dental hygiene science
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• v.18 no.4
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• pp.201-209
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• 2018

The aim of this study was to identify bibliographic characteristics and research trends of articles published on the elderly people in dental hygiene. An analysis was done of 191 articles published from 1999 to 2017. Bibliographic characteristics were nine items such as publication journal, research design, research participants, number of researchers, data analysis method, keywords, research topic, and validity and reliability report. The collected data were analyzed using descriptive statistics of statistical program. First, the research on the elderly, which was published in dental hygiene, started to be published in 1999 and on going. Though major publications have been published in Journal of Korean Society of Dental Hygiene and Journal of Dental Hygiene Science, the kinds of journals are becoming diverse. Second, cross-sectional research was the most. Third, the elderly were the most studied subjects, but the criteria varied. Fourth, the number of authors was largest in order of two and three person. Fifth, data analysis method was in order of descriptive statistics, t-test, and ANOVA. Sixth, there were many duplication of keywords about oral, elderly, and health. Seventh, oral health behavior science was the most studied subject. Eighth, validity and reliability were reported at 27.4% and 51.6%, respectively. Ninth, only 15.7% of study was founded research funding. Based on the results of this study, we consider increase experimental research further. Therefore, it is recommeded that validity and reliability should be reported in research paper, and the keywords used in the field of dental hygiene should be agreed upon.

• Journal of agricultural medicine and community health
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• v.34 no.2
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• pp.223-233
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• 2009

Objectives: This study aimed to examine the relations between exposure to anti-smoking promotion media and smoking, targeting middle school students who were exposed to various media of promotion. Methods: The subjects of the study were 38,820 middle school students who answered to the 2007 Korea Youth Risk Behavior Web-based Survey. Answers of 37,714 subjects were used for the final analysis except those of 1,106 that could not be used to judge anti-smoking promotion media and prevalence of smoking as they were considered insincere to the questions. We used SPSS of version 17.0. This study conducted a chi-square test to identify smoking rate according to characteristics of subjects and a multivariate logistic regression analysis to identify whether they are independently significant. Results: Smoking rate increased as the subjects were in higher grades. From the results of multivariate logistic regression, odds ratio(OR) at points 5~6 of the first graders that had never been exposed to anti-smoking promotion media was 0.49(95% CI=0.33-0.74), which was significantly low. And OR at points 5~6 of the third graders was 0.57(95% CI=0.43-0.76), significantly low. Conclusions: This study identified the relations between exposure to anti-smoking promotion media and smoking of middle school students in Korea.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.1
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• pp.81-94
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• 2010

This paper deals with the fracture simulation of UHPFRC girder with the interface type model. Based on the existing numerical simulation of quasi-brittle fracture in normal strength concrete, constitutive modeling for UHPFRC I-girder has been improved by including a tensile hardening at the failure surface. The finite element formulation is based on a triangular unit, constructed from constant strain triangles, with nodes along its sides and neither at the vertex nor the center of the unit. Fracture is simulated through a hardening/softening fracture constitutive law in tension, a softening fracture constitutive law in shear as well as in compression at the boundary nodes, with the material within the triangular unit remaining linear elastic. LCP is used to formulate the path-dependent hardening-softening behavior in non-holonomic rate form and a mathematical programming algorithm is employed to solve the LCP. The piece-wise linear inelastic yielding-failure/failure surface is modeled with two compressive caps, two Mohr-Coulomb failure surfaces, a tensile yielding surface and a tensile failure surface. The comparison between test results and numerical results indicates this method effectively simulates the deformation and failure of specimen.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.1
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• pp.35-42
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• 2008

In the nuclear power plant, early detection of fatigue crack by non-destructive test (NDT) equipment due to the thermal cyclic load is very important in terms of strict safety regulation. To this end, many efforts are exerted to the fabrication of artificial cracked specimen for practicing engineers in the NDT company. The crack of this kind, however, cannot be made by conventional machining, but should be made under thermal cyclic load that is close to the in-situ condition, which takes tremendous time due to the repetition. In this study, thermal loading condition is investigated to minimize the time for fabricating the cracked specimen using simulation technique which predicts the crack initiation and propagation behavior. Simulation and experiment are conducted under an initial assumed condition for validation purpose. A number of simulations are conducted next under a variety of heating and cooling conditions, from which the best solution to achieve minimum time for crack with wanted size is found. In the simulation, general purpose software ANSYS is used for the stress analysis, MATLAB is used to compute crack initiation life, and ZENCRACK, which is special purpose software for crack growth prediction, is used to compute crack propagation life. As a result of the study, the time for the crack to reach the size of 1mm is predicted from the 418 hours at the initial condition to the 319 hours at the optimum condition, which is about 24% reduction.

• Management & Information Systems Review
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• v.31 no.4
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• pp.593-609
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• 2012

This study is designed to investigate whether the information spillover effect is existed between the foreign investors' unexpected volatility of net purchasing intensity and the volatilities of returns in terms of daily closing stock return, overnight return, and daytime return, before and after financial crisis in Korea. The result of this study shows that there is negative information spillover effect between the foreign investors' unexpected volatility of net purchasing intensity and the volatility of daily closing stock return for time t-1. However, there is an opposite result for time t, showing positive information transmission effect. For the overnight return, the test result provides there is no statistical significance between the foreign investor's unexpected volatility of net purchasing intensity and the volatilities of return. In addition, I found that the information transmission effect is existed between the foreign investor's unexpected volatility of net purchasing intensity and the volatilities of the daytime return for the entire timeline.

• Management & Information Systems Review
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• v.36 no.5
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• pp.99-120
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• 2017

Recent studies shows that international entrepreneurship orientation is recognized as a very important tool for improving corporate performance in international business activities. However, these relationships show various research results. Therefore, it can be a very interesting research topic to examine whether these relationships are linear or non-linear when selected as a target in developing country like China. The purpose of this study is to examine whether the effects of international entrepreneurship orientation on the export performance is non-liner type in China's manufacturing firms. And investigated the moderating role of degree of internationalization and market dynamism relative to the relationship between the international entrepreneurial-orientation and the export performance. A total of 478 questionnaires were used for the hypothesis test. The results of this study are summarized as follows: First, there is a J-shaped. relationship between international entrepreneurship orientation and export performance. Second, degree of Internationalization strengthened the reverse J-shaped relationship between international entrepreneurship orientation and export performance. Finally, degree of internationalization and market dynamics show that J-shaped relationship between international entrepreneurial orientation and export performance is strengthened. The results of the study's theoretical contribution and the managerial contribution is as followed. As a theoretical contribution, it is confirmed that international entrepreneurial orientation (J-shaped) and export performance form a non-linear relationship, and it is possible to make an empirical contribution that can newly approach the relationship between international entrepreneurial orientation and export performance. The managerial contribution suggests that China's exporting companies have a higher degree of Internationalization in their international business activities and that the higher the dynamics of the overseas markets, the more advanced the international entrepreneurial behavior should be required to improve the export performance.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.2
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• pp.212-234
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• 1999

Dental restorative materials must have the physical properties to withstand wear and corrosion. Base metal alloys possess better mechanical properties and lower price than the gold alloys. For these reasons such alloys have largely replaced the precious metal alloys. One aspect to con-sider is the release of metal substances to oral environment. The release of elements from dental alloys is a continuing concern because the elements may have the potentially harmful biological effects on local tissues. The purpose of this study was to minimize metal release on the nonprecious metal surfaces by ion beam assisted deposition(IBAD) of titanium nitride (TiN) Ni-Cr-Be alloys with and without TiN coatings were secured in an wear test machine opposing ruby ball to determine their relative resistance to wear with loom, 200m, 300m and 400m sliding distance. And the corrosion behavior of the Ni-Cr-Be alloys with and without TiN coatings and 3 dental noble alloys have been studied. Potentiodynamic curves were used to analyse the corrosion characteristics of the alloys. The measurement of the released Ni and Cr ions was conducted by analysis of the electrolyte solution with atomic absorption spectroscopy. The results were as follows : 1. The critical sliding distance that wore down TiN coatings of $2.5{\mu}m$ thickness in this study condition was 300m. 2. Ion beam assisted deposition of TiN showed a good surface modification with respect to the properties of wear and corrosion resistance. 3. X-ray diffraction showed that the strongest peak of TiN is TiN(111) in the coatings. 4. The release of Ni and Cr ions from alloys measured by means of atomic absorption spectroscopy was reduced by ion beam assisted deposition of TiN.