• Journal of dental hygiene science
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• v.7 no.3
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• pp.161-166
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• 2007

Relationship of Dental Health Assessment to the Number of Existing Permanent Tooth in Senior Citizens visited a dental hospital or clinic from Some Regions. The purpose of this study was to examine the relationship of the dental health assessment of elderly people who were at the age of 65 and up to the number of existing permanent tooth in an effort to lay the groundwork for pinpointing problems with their oral status and developing programs geared toward improving their dental health and quality of life. The findings of the study were as follows: 1. Regarding self-perceived dental health, the largest group of the senior citizens that accounted for 57.9 percent didn't find themselves to be in good dental health. The second largest group that represented 32.5 percent thought their dental health was at an ordinary level, and the third greatest number of them that stood at 9.5 percent considered themselves to be in good dental health. Their self-perceived dental health status was statistically significantly different according to education and monthly income, and whether they had a job or not made a statistically significant difference to that as well(p < .01, p < .001). 2. In terms of taste appreciation, 58.7 percent, the largest group, didn't appreciate one or two kinds of taste, and their taste appreciation was statistically significantly different according to education and monthly income(p < .05, p < .01). 3. As for chewing ability, 20.6 percent were able to chew well. In regard to digestion, 69.0 percent had an ordinary level of digestive power. 4. Concerning the number of existing permanent tooth, 38.9 percent, the greatest percentage, had ten or less permanent teeth. By education, the possession of 21or more permanent teeth(40.0%) was most common among those who received high-school or higher education. The greatest group of the senior citizens with a job had 11 to 20 permanent teeth(41.7%), and the largest number of the elderly people whose monthly income was 500 thousand won or more were in possession of 11 to 20 permanent teeth(41.7%). The number of existing permanent tooth statistically significantly differed with their general characteristics(p < .01). 5. As to connections between dental health and the number of existing permanent tooth, 21 permanent teeth or more were owned by those who were in good dental health, who appreciated different tastes and whose chewing ability was good. So there was a statistically significant relationship between the two.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.1
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• pp.65-78
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• 2018

According to the in social aspects such as population growth, urbanization and industrialization, development of livestock industry by meat consumption, amount of organic wastes (containing sewage sludge and food waste, animal manure, etc) has been increased annually in South Korea. Precise monitoring of 11 organic wastes biogas facilities were conducted. The organic decomposition rate of organic wastewater was 68.2 % for food wastes, 66.8 % for animal manure and 46.2 % for sewage sludge and 58.8 % for total organic wastes. As a result of analyzing the biogas characteristics before and after the pretreatment, the total average of the whole facility was measured to be 560 ppm using iron salts and desulfurization, and decreased to 40 ppm when the reduction efficiency was above 90 %. Particularly, when iron salt is injected into the digester, the treatment efficiency is about 93 %, and the average is reduced to 150 ppm. In the case of dehumidification, the absolute humidity and the relative humidity were analyzed. The dew point temperature of the facility where the dehumidification facility was well maintained as $14^{\circ}C$, the absolute humidity was $12.6g/m^3$, and the relative humidity was 35 %. Therefore, it is necessary to compensate for the disadvantages of biogasification facilities of organic waste resources and optimize utilization of biogas and improve operation of facilities. This study was conducted to optimize biogas utilization of type of organic waste(containing sewage sludge and food waste, animal manure) through precision monitoring.

• Journal of the Mineralogical Society of Korea
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• v.23 no.2
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• pp.125-139
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• 2010

Behavior of heavy metals and arsenic in the tailings of Songcheon Au-Ag mine was characterized via both mineralogical and geochemical methods. Mineral composition of the tailings was investigated by X-ray diffractometry, energy-dispersive spectroscopy, and electron probe micro-analyzer (EPMA) and total concentrations of heavy metals and arsenic and their chemical forms were analyzed by total digestion of aqua regia and sequential extraction method, respectively. The results of mineralogical study indicate that the tailings included mineral particles of resinous shape mainly consisting of galena, sphalerite, pyrite, quartz, and scorodite, and specifically socordite was identified in the form of matrix. EPMA quantitative analyses were performed to evaluate the weatherability of each mineral, and the results suggest that it decreased in the sequence of arsenopyrite > galena > sphalerite > pyrite. The weathering pattern of galena was observed to show distinctive zonal structure consisting of secondary minerals such as anglesite and beudantite. In addition, almost all of arsenopyrite has been altered to scorodite existing asmatrix and galena, sphalerite, and pyrite which have lower weatherability than arsenopyrite were identified within the matrix of scorodite. During the process of alteration of arsenopyrite into scorodite, it is likely that a portion of arsenic was lixiviated and caused a great deal of detrimental effects to surrounding environment. The results of EPMA quantitative analyses verify that the stability of scorodite was relatively high and this stable scorodite has restrained the weathering of other primary minerals within tailings as a result of its coating of mineral surfaces. For this reason, Songcheon tailings show the characteristics of the first weathering stage, although they have been exposed to the surface environment for a long time. Based on the overall results of mineralogical and geochemical studies undertaken in this research, if the tailings are kept to be exposed to the surface environment and the weathering process is continuous, not only hazardous heavy metals, such as lead and arsenic seem to be significantly leached out because their larger portions are being partitioned in weakly-bound (highly-mobile) fractions, but the potential of arsenic leaching is likely to be high as the stability of scorodite is gradually decreased. Consequently, it is speculated that the environmental hazard of Songcheon mine is significantly high.