DISTRIBUTION OF AIRBORNE BACTERIA BY HANDPIECE AEROSOL CONDITIO (핸드피스 분무조건에 따른 부유세균 기균(氣菌) 의 분포)
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- Journal of the korean academy of Pediatric Dentistry
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- v.35 no.4
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- pp.628-634
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- 2008
In recent years, cross-contamination has become one of the noticeable issues in dental clinic. Two major routes of contamination are the direct-contamination through blood and oral secretion and the indirect-contamination through dental office equipments. Especially, air-contamination through air-floating pollutant in a confined space like hospital, and also contamination through aerosol ejected from high-speed handpiece in a dental office was interested. The purpose of this study was to understand risk of bacterial infection through aerosol from handpiece in a dental office, which will help the practitioner with prevention of contamination during dental treatment. The main findings are as follows. 1. In a comparative test, the group using handpiece has higher bacterial number than the group not using handpiece with significant statistical difference(P<0.01). 2. The group using handpiece with rubber dam has lower bacterial number than the group using handpiecewithout rubber dam with significant statistical difference(P<0.01). 3. Comparing the group using drainage water with the group using distilled water as a handpiece water source results in 22.4 cfu and 17.0 cfu respectively but the difference is no statistically significant(P>0.05). 4. Measuring cfu at 0.5m and 1.5m distance, 0.5m distance showed higher bacterial number with statistical significance(P<0.01). 5. Classification of bacterial types showed the largest bacterial number came from gram-positive micrococcus(73.9%), and gram-negative micrococcus, gram-negative bacillus, and gram-positive bacillus follow in descending order.
The purpose of this study was assessment the quality of water by using the statistical analysis technique of the Water flow and water quality from January 2012 to December 2016 at the unit basin for total pollutant load management system (TPLMS) in the Imjin River. Water flow and water quality were monitored at an average of 8 day intervals, 11 parameters were used for correlation analysis, principal component analysis (PCA), factor analysis (FA), and cluster analysis (CA). The Hierarchical CA was classified into three according to the change of space, such as natural rivers, urban rivers, point with large influence of point pollution source, it was found that the type of contamination source the similarity of water quality affected the classification of cluster. Using one-way analysis of variance (ANOVA) and post-hoc Analysis, there were statistically significant differences between mean values among the clusters. Correlation analysis showed the correlation coefficient between
This study is attempted to establish the concept of Byeulseo Scenic Spot that the definitions of Byeulseo and Scenic Spot would be presented first followed by clarifying the basis, reason and justification that Byeulseo would be called as Byeulseo Scenic Spot that the following is the major results formulated herein. First, the concept of scenic spot under the Cultural Property Act is the reference to the famous site with the building improvement well known for its great scenery or the point where splendid scenery is viewed that has the artistic value along with the trace of human lives in this cultural heritage that, although the scenery is important but the attention has to be on discovery of historic resources with the story telling in the subject site. Second, the criteria of designation on the Scenic Spot in Korea would be natural scenery, animal and plant site with well-known scenery, view point of scenery, famous building or garden and important places with legend that there lacks diversification. In this aspect, the intent of the concept of Scenic Spot would be facilitated to expand the designation of the Byeulseo Scenic Spot as the Scenic Spot of living style. Third, from the foreign cases, particularly, in Japan, it is needed to note that Byeulseos and housing gardens are designated for 196 places of Scenic Spot, reaching 55.4% of entire Scenic Spots. Laws, regulations, systems and designated criteria on the cases of designating the foreign Scenic Spots would be studied and quoted. Fourth, the classification work for each type to designate as cultural heritage has to be continued as the Scenic Spot of subject site with even more emerged for the value as the Scenic Spot in garden, original site and the like classified as historic site, important folk data and the like. Fifth, the designation of Scenic Spot of Byeulseo garden with splendid scenery as the living Scenic Spot has to be expanded. The pavilion existed now nationwide would be approximately 1,500, and these pavilions are the place where the scholars stay in the famous site, and this is the central space of Byeulseo to study, and if there is clear one that has written and record of deed to create the stories to people with the value for publicity campaign, it would be the subject of Scenic Spot. And sixth, for the case of view point with splendid scenery in Byeulseo Garden, it cannot be the subject of designation that the designation of Scenic Spot has to be expanded. In the event of the Byeulseo garden in Korea, there are many cases of having outstanding view points, and there is a few case of designating the subject site with great view point as a Scenic Spot.
This study empirically examines the impact of SSM market entry on changes in market shares among retailing types. The data is monthly time-series data spanning over the period from January 2000 to December 2010, and the effect of SSM market entry on market shares of retailing types is analyzed by utilizing several key factors such as the number of new SSM monthly entrants, total number of SSMs, the proportion of new SSM entrant that is smaller than