• Journal of the Korean Dietetic Association
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• v.23 no.2
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• pp.180-191
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• 2017

The purpose of this study was to identity the probability of cross-contamination from the environment. For this, we examined foodservices at 20 universities/colleges for microbiological analysis of their working facilities and environment as well as their preventive equipment against cross-contamination. Seventy percent of the 20 foodservices were found to maintain one unified working area, which suggests high probability of contamination of food/utensils/equipment in the cooking area by pre-preparation or dish washing. According to the microbiological analysis, the hygiene acceptance ratio of working facilities in the clean zone was 70%, which was higher than the average 45% hygiene acceptance ratio of working facilities in the contamination operating zone. There was a significant difference in the total plate count (P<0.001) and coliform count (P<0.01), which demonstrates that work tables in the clean zone were in a good state compared to those in the contamination operating zone. In the contamination operating zone, refrigerator shelves had a high probability of cross-contamination. Regarding the floor surface and airborne microbes, cooking areas which should be maintained as clean zones had higher cross-contamination probability than those in the contamination operating zone. So corrective actions such as cleaning and sanitizing, keeping dry floors, lowered temperature and humidity, shoe disinfecting facilities, and checking concentrations, are necessary to manage floor surfaces and airborne microbes in the cooking area.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2333-2337
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• 2007

The practical studies on the method of particle contamination control for yield enhancement in the cleanroom were carried out. The method of the contamination control was considered, which is composed of data collection, data analysis, improvement action, verification, and implement control. The composition analysis for data collection and data analysis was used in the cellular phone module packaging lines. And this method was evaluated by the variation of yield loss between before and after improvement action. In case that the composition analysis was applied, the critical sources were selected and yield loss reduction through improvement actions was also investigated. From these results, it is concluded that the composition analysis is effective solutions for particle contamination control in the cleanroom.

• Environmental Analysis Health and Toxicology
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• v.31
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• pp.6.1-6.10
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• 2016

Objectives This study examined the spatial distribution and the extent of soil contamination by heavy metals resulting from primitive, unconventional informal electronic waste recycling in the Agbogbloshie e-waste processing site (AEPS) in Ghana. Methods A total of 132 samples were collected at 100 m intervals, with a handheld global position system used in taking the location data of the soil sample points. Observing all procedural and quality assurance measures, the samples were analyzed for barium (Ba), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), and zinc (Zn), using X-ray fluorescence. Using environmental risk indices of contamination factor and degree of contamination ($C_{deg}$), we analyzed the individual contribution of each heavy metal contamination and the overall $C_{deg}$. We further used geostatistical techniques of spatial autocorrelation and variability to examine spatial distribution and extent of heavy metal contamination. Results Results from soil analysis showed that heavy metal concentrations were significantly higher than the Canadian Environmental Protection Agency and Dutch environmental standards. In an increasing order, Pb>Cd>Hg>Cu>Zn>Cr>Co>Ba>Ni contributed significantly to the overall $C_{deg}$. Contamination was highest in the main working areas of burning and dismantling sites, indicating the influence of recycling activities. Geostatistical analysis also revealed that heavy metal contamination spreads beyond the main working areas to residential, recreational, farming, and commercial areas. Conclusions Our results show that the studied heavy metals are ubiquitous within AEPS and the significantly high concentration of these metals reflect the contamination factor and $C_{deg}$, indicating soil contamination in AEPS with the nine heavy metals studied.

• Journal of the Korean Geophysical Society
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• v.7 no.2
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• pp.121-134
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• 2004

This study has tried to develop the modified DRASTIC Model by supplying the parameters, such as structural lineament density and land-use, into conventional DRASTIC model, and to predict the potential of groundwater contamination using GIS in Hwanam 2 District, Gyeonggi Province, Korea. Since the aquifers in Korea is generally through the joints of rock-mass in hydrogeological environment, lineament density affects to the behavior of groundwater and contaminated plumes directly, and land-use reflect the effect of point or non-point source of contamination indirectly. For the statistical analysis, lattice-layers of each parameter were generated, and then level of confidence was assessed by analyzing each correlation coefficient. Groundwater contamination potential map was achieved as a final result by comparing modified DRASTIC potential and the amount of pollutant load logically. The result suggest the predictability of contamination potential in a specified area in the respects of hydrogeological aspect and water quality.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.116-122
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• 2010

It is necessary to be careful about contamination control to minimize the accumulation of the contamination material on satellite surface during the I&T phase. In the space environment which characterized by high vacuum, high and very low temperature, contamination material causes satellite to lose its own performance. Especially, contamination material can accumulate on critical surfaces such as lenses, mirrors, and sensors. KARI(Korea Aerospace Research Institute) conducts the clean room to control and minimize the contamination effect. This paper introduces the principle of contamination and the method of measure and analysis for the contamination.

• Analytical Science and Technology
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• v.31 no.3
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• pp.122-133
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• 2018

In this study, groundwater quality data measured for 11 years from 2006 to 2016 were analyzed statistically for 101 civil defense emergency water supply facilities (CDEWSF) in the Gwangju area. The contamination level was quantified into four grades by using excess drinking water quality standards, average concentration analysis, and tendency analysis results for each facility. On the basis of this approach, the groundwater contamination degree of each item was evaluated according to land use status, installation year, depth, and geological distribution. The contamination grade ratios, which were obtained by analyzing three contamination indicators (water quality exceeded frequency, average concentration analysis, and trend analysis) for 15 items on statistically significant of civil defense emergency water was relatively high, in the order of Turbidity (51.5 %) > Color (32.7 %) > Nitrate nitrogen (28.7 %) > Hardness (25.7 %). As a result of the contamination grade analysis, except for the items of Turbidity, Color, and Nitrate nitrogen, the contamination levels were distributed in various degrees from "clean (0)" to "seriously contaminated (3)." Regarding the contamination grade of 12 items, 25 % of the total were classified as "possibly contaminated (1)," and 75 % were rated "clean (0)." The four items (Turbidity, Color, Nitrate nitrogen, and Hardness) for which contamination indication rate were evaluated as "high" by the were visualized on a contamination map.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.6 s.261
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• pp.522-530
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• 2007

The practical studies on the method of particle contamination control for yield enhancement in the cleanroom were carried out. The method of the contamination control was proposed, which are composed of data collection, data analysis, improvement action, verification, and implement control. The partition check method and the composition analysis for data collection and data analysis were respectively used in the main board and the cellular phone module production lines. And these methods were evaluated by the variation of yield loss between before and after improvement action. In case that the partition check method was applied, the critical process step was selected and yield loss reduction through improvement actions was observed. While in case that the composition analysis was applied, the critical sources were selected and yield loss reduction through improvement actions was also investigated. From these results, it is concluded that the partition check and the composition analysis are effective solutions for particle contamination control in the cleanroom production lines.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.28.3-28.3
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• 2008

Contamination has the potential for degrading the performance of the optical payload beyond the limits defined by mission requirements, therefore it must be considered a risk to system performance and must be mitigated. To mitigate contamination problem, contamination budget is allocated according to the contamination requirements which is derived from contamination effect analysis. Once the contamination budget is allocated, prediction for on-ground and in-orbit contaminants amounts and cleanliness control is performed. In this article, typical contamination control for observation satellite is described.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.393-398
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• 2006

This study is undertaken to evaluate the characteristics of cross contamination around exterior air-vents. A CFD analysis has been performed to calculate the cross contamination index for five exterior air-vents sizes according to the outdoor air velocity and separation distance of it. From the result of the numerical method, As the outdoor air velocity is increased, the cross contamination index is increased. on the contrary, as the separation distance of exterior air-vents is increased, the cross contamination index is decreased, additionally the cross contamination is affected by the aspect ratio of the size of exterior Air-vents.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.440-443
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• 2003

Recently, with the rapid growth of industry, environmental condition became worse. With the mix of the various contaminants, such as, salts, dust and industrial pollutants, synergy effect could be happened. So, many researches have been focused on the issue. The cause of natural accident could be classified as, lightning, rainstorm and contamination. However, the accident by contamination influences on the larger area than that by lightning, and, in the case of rapid contamination, it takes a shorter time than rainstorm. The salt contaminant is one of the most representative pollutants, and known as the main source of the accident by contamination. So, in this investigation we make a research on the prediction of contamination degree through the relationship analysis between the climatic factor and ESDD.