• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.230-236
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• 2019

Recently, issues related to the quality of concrete have continuously resulted in surface quality problems, such as the exfoliation of concrete surfaces due to the cost reduction of cement and poor quality fine aggregate, scaling of surfaces caused by laitance, and plastic shrinkage cracks. Prompted by social issues, the application of a photo catalyst to road structures is being attempted to solve the environmental problems caused by fine dust and automobile exhaust. In this study, chemical admixtures were developed to improve the surface quality of concrete and to apply and distribute titanium dioxide in nanoscale sizes to provide basic data for the development of a photocatalyst-curing agent. As a result of the experiment, silicon and silane were reviewed as a raw material as a curing agent to develop a high performance curing agent with better film performance than conventional curing agents because they could form a film quickly on a fresh concrete surface. The distributed stability of the ultrasonic disperser showed the best performance through an outdoor test for four weeks to review the dispersion measures for the application of nanomaterials.

• Journal of Korean society of Dental Hygiene
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• v.16 no.5
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• pp.651-660
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• 2016

Objective: The purpose of the study is to investigate clinical skill proficiency in core dental hygiene competency in dental hygienists. Methods: The study subjects were 208 dental hygienists in Seoul and Gyeonggido. A complete self-reported questionnaire was filled out by 171 dental hygienists. The questionnaire consisted of general characteristics of the subjects, assessment of core dental hygiene competency, implementation of core dental hygiene competency, and education of core dental hygiene competency. Data were analyzed by PASW Statistics 18.0 to carry out a frequency analysis, one-way ANOVA and Pearson's correlation. Results: Chief complaint confirmation($4.08{\pm}0.91$), scaling (ultrasonic scaler)($4.36{\pm}0.88$), and toothbrushing education($4.35{\pm}0.86$) were found to be the most important in the areas of dental hygiene assessment, implementation, and education, respectively. In dental hygiene education, statistically significant differences were identified by 'level of education,' 'working career,' 'type of workplace,' 'department,' and 'main task.' Conclusions: Respondents were found to think that their level of proficiency should be above average for most jobs. Proficiency in core competency was shown to be different according to 'general characteristics of dental hygienists,' 'type of workplace,' and 'department.'

• Economic and Environmental Geology
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• v.56 no.6
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• pp.697-714
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• 2023

The Tracksite of Cretaceous Dinosaurs and Pterosaurs in Jeongchon, Jinju was discovered in late 2017 during the construction of the Ppuri industry complex. This site is a natural heritage site with a high paleontological value, as it preserves fossils of various types of dinosaurs, pterosaurs, and animal traces at a dense concentration. In this study, we surveyed that physical weathering such as joint, crack, scaling, exfoliation, and fragmentation occurred through field research in the fossil site, and conducted basic research on conservation science to reduce the damage. To this end, among the eight levels identified after excavation, the rocks of Level 3, which yielded a large number of theropod footprint fossils, and Level 4, which yielded pterosaur footprint fossils, were analyzed for material characteristics and evaluation of the effectiveness of consolidation and adhesion. This results showed that the rocks in the Level 3 stratum were dark gray siltstone and the rocks in the Level 4 stratum were dark gray shale, which contained a large amount of calcite and were composed of quartz, plagioclase, mica, alkali feldspar, and other clay minerals, which are likely to be damaged by rainfall under external conditions. As a result of conducting an artificial weathering experiment by dividing the probationary sample into four groups: untreated, consolidation treatment, anti-swelling treatment, and adhesive treatment, the consolidation and the swelling inhibitor showed an effect immediately after treatment, but did not show a blocking effect under a freezing-thawing environment. The adhesive showed that the adhesive effect was maintained even under freezing-thawing conditions. In order to preserve the fossil sites at Jeongchon in the future, in addition to temporary measures to block the inflow of moisture, practical measures such as the construction of protective facilities should be prepared.