• Journal of Environmental Health Sciences
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• v.7 no.1
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• pp.51-57
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• 1981

This Study was carried out to investigate yeast and mold contamination in fermented milk products produced by 9 different domestic manufacturers from October 20. to December 5. 1980 The results obtained in the study were as follows 1) pH values of the products were ranged from pH 3.14 to pH 4.20 and average of sour milk drinks was pH $3.66\pm 0.19$ and fermented milks pH $3.74\pm 0.11$. Therefore the difference of pH average among sour milk drinks and fermented milks was statistically significant. (p<0.01) 2) In case of yeast contamination, yeast was found on all the four producted at the same date. From this result, it seemed that yeast contamination occured during the manufacturing progress. 3) Degree of contamination by the indicator organisms was E. coli positive, 3.7%: over 1,000 yeasts/ml, 14.8% over 10 molds/ml, 0.9%. 4) In the range of over 1,000 yeasts/ml, degree of contamination by yeast was 8.4% in fermented milk and 16.7% in sour milk drink. 5) Yeasts in product C increased to the spoilage number within 5 days and in H increased within 10 days at 5C. At 15$\circ$C, yeast increased to the spoilage number within 15 days in product A.D. 6) It seems that the yeast number of initial contamination should be important than the increase rate as criteria on the fermented Milk products.

• Journal of Pharmaceutical Investigation
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• v.3 no.4
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• pp.5-15
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• 1973

An investigation was carried out on a basis of the bacteriological examination with a view to detecting the degree of bacterial contamination for the 77 samples collected from the locally-sold liquid specialties. It's test period was 50 days from July 10 to August 30, 1971. Specially, the survey has put emphasis on the population of general bacteria and the identification of coli-form group, staphylococcus species, streptococcus species, bacillus species, fungi, and yeast species from liquid samples. The results obtained are summarized as follows; (1) For the 77 samples tested, the contamination of general bacteria was found out as minimun 0, i,e., maximum, $12{\times}10^4$ and the total average $45{\times}10^2$ per milliliter. (2) Although streptococcus species could not be detected with the samples, the contamination of the coli-form and staphylococcus species means the strong suggestion of the possibility of pathogenic bacterial contamination. (3) Specially, the products which stay in the neutral pH range and use suspending agents need to care for the microbial contamination in the manufacturing crocess. (4) It is thought necessary to perform the microbiological quality control in the liquid preparations only at least. (5) As the microbial contamination degree in the liquid decreases according to the elapse of time, the microbiological quality control will have to be carried out immediately after the completion of the manufacturing process in order to know the accurate degree. (6) The author thinks that the main reason of the microbial contamination in the liquid is the contamination during the manufacturing process. (7) For the purpose of prevention of the microbial contamination in liquid, therefore, it is more important to make efforts for the rationalization of manufacturing process, the improvement of equipment and environment, the specific training of workers for hygienic knowledges, etc. rather than the use of preservatives for the preparations.

• Clinical and Experimental Pediatrics
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• v.57 no.4
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• pp.178-185
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• 2014

Purpose: Blood culture is the most important tool for detecting bacteremia in children with fever. However, blood culture contamination rates range from 0.6% to 6.0% in adults; rates for young children have been considered higher than these, although data are limited, especially in Korea. This study determined the contamination rate and risk factors in pediatric patients visiting the emergency room (ER) or being admitted to the ward. Methods: We conducted a retrospective chart review of blood cultures obtained from children who visited Yonsei Severance Hospital, Korea between 2006 and 2010. Positive blood cultures were labeled as true bacteremia or contamination according to Centers for Disease Control and Prevention/National Healthcare Safety Network definitions for laboratory-confirmed bloodstream infection, after exclusion of cultures drawn from preexisting central lines only. Results: Among 40,542 blood cultures, 610 were positive, of which 479 were contaminations and 131 were true bacteremia (overall contamination rate, 1.18%). The contamination rate in the ER was significantly higher than in the ward (1.32% vs. 0.66%, P<0.001). The rate was higher in younger children (2.07%, 0.94%, and 0.61% in children aged <1 year, 1-6 years, and >6 years, respectively). Conclusion: Overall, contamination rates were higher in younger children than in older children, given the difficulty of performing blood sampling in younger children. The contamination rates from the ER were higher than those from the ward, not accounted for only by overcrowding and lack of experience among personnel collecting samples. Further study to investigate other factors affecting contamination should be required.

• Advances in concrete construction
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• v.4 no.3
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• pp.195-206
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• 2016

Today, application of additives to replace cement in order to improve concrete mixes is widely promoted. Micro-silica is among the best pozzolanic additives which can desirably contribute to the concrete characteristics provided it is used properly. In this paper, the effects of AP2RC and P1RB micro-silica gels on strength characteristics of normal concrete are investigated. Obtained results indicated that the application of these additives not only provided proper workability during construction, but also led to increased tensile, compressive and flexural strength values for the concrete during early ages as well as ultimate ones with the resulting reduction in the porosity lowering permeability of the micro-silica concrete. Furthermore, evaluation of microbial contamination of the mentioned gels showed the resultant contamination level to be within the permitted range.

• Nuclear Engineering and Technology
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• v.56 no.7
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• pp.2775-2780
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• 2024

Special methods for cleaning surfaces of stainless steel with a coating simulating radioactive contamination have been developed and studied. The removal of simulated surface contamination was performed using lasers in the micron spectral range with pulse durations of 8 ns and 270 fs. Optimal cleaning modes were determined for gas and liquid environments, achieving surface cleaning coefficient of over 90% in a single pass. A correlation between the degree of cleaning in liquids and the viscosity of the environment was discovered.

• The Journal of Engineering Geology
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• v.16 no.4 s.50
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• pp.393-402
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• 2006

The contamination characteristics of BTEX and TPH components in silty soils with the oil leakage event from point source were studied. The over ratios of three soil pollution standard for TPH component were $1.5{\sim}1.7$ times higher than that of BTEX component. The mean and maximum values of BTEX and TPH components with sample points were B-zone > A-zone > C-zone, and the highest concentrations were measured at $1{\sim}2m$ depth below surface. BTEX and TPH components were increased with linear distance in zone within 120 m and 80 m from point source. For the zone more than 120 m, BTEX and TPH concentrations were under soil pollution standard. The cutoff values of indicator kriging using BTEX and TPH components were defined as confirmative limit, warn- ing limit and counterplan limit. The variograms of indicator-transformed data were selected linear model. The contamination ranges of BTEX and TPH components using confirmative limit and warning limit were estimated similar, but the contamination range of those using counterplan limit was much reduced. The maximum contamination probabilities were estimated by probability maps usinB confirmative limit, warning limit and counterplan limit. The maximum contamination probabilities with three soil pollution standard were estimated 26%, 26% and 13% for BTEX component, and 44%, 38% and 26% for TPH component.

• Journal of Soil and Groundwater Environment
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• v.23 no.1
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• pp.54-62
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• 2018

This paper is aimed at source tracking of soil heavy metal contamination at a site established by reusing construction wastes. The soil heavy metal concentration at the study site peaked at a depth range of 5-10 m. Column studies were conducted to investigate the possibility of the contamination scenario of infiltration of stormwater carrying heavy metals of ground origin followed by selective heavy metal accumulation at the 5-10 m depth range. Almost all amount of lead, zinc, cadmium, and nickel introduced to the columns each packed with 0-5 m or 5-10 m field soil were accumulated in the column. The very poor heavy metal mobility in spite of the weak association of the heavy metals with the soil (characterized by a sequential extraction procedure) can be attributed to the high pH (10-11) of the construction wastes. From the results, the heavy metal contamination of the subsurface soil by an external heavy metal source was determined to be very unlikely at the study site. The column study applied in the current study is expected to be a useful methodology to present direct evidence of the contaminant source tracking at soil contamination sites.

• Journal of Environmental Impact Assessment
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• v.22 no.5
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• pp.481-489
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• 2013

There are U.S. troops with a force about 290,000 strong stationed all around the world, approximately 150 countries. Among the troops, USFK has performed principal part with its stationing for 50 years against the military threat of North Korea. However, as a result of an investigation made into environmental contamination of several bases which were restituted from US to ROK by the Land Partnership Plan in the process of relocation of USFK, it was found that the area was contaminated by not only TPH and BTEX caused by diesel fuel and JP-8 but also various heavy metal over the standard level according to the operations of corps. Among these bases, 4 corps, each of which has different duties and function, were chosen to be analyzed for the characteristics and degrees of soil contamination. Fisrt of all, in armored camp the soil was contaminated by TPH and heavy metal (Zn, Ni, Pb) due to the repairing activities of tracked vehicles and shooting exercises. In army aviation camp, the soil was contaminated by TPH, BTEX and heavy metal (Zn, Cd) due to repairing activities of aircrafts. Also, in engineer camp there was contaminated area polluted by TPH and heavy metal (Zn, Pb) caused by open-air storage of various construction materials and TPH, BTEX and heavy metal (Zn, Pb, Cu) contamination of aircraft shooting area in shooting range camp were detected. Managing environment will be more effective when we identify the contaminative characteristics and take necessary measures in advance.

• Environmental Mutagens and Carcinogens
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• v.23 no.2
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• pp.51-55
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• 2003

Benzo(a)pyrene and bisphenol A have been classified as endocrine disrupting chemicals (EDCs), which have been of concern in toxicology and environmental sciences. Benzo(a)pyrene and bisphenol A were monitored by HPLC or GC-MS in Baekwoon and Ilwirl lakes of Kyonggi-Do province to investigate contamination levels of EDCs. During the period between June, 2000 and August, 2000, water samples were collected from four different sites of each lake once per month. Contamination levels of benzo(a)pyrene were 3.27~4.25 ppb in Ilwirl lake and 2.00~2.33 ppb in Baekwoon lake, respectively. Bisphenol A levels were detected with the range of 0.33~7.94 and 0.43~4.71 for Baekwoon lake and Ilwirl lake, respectively. pH levels were higher in Ilwirl lake than in Baekwoon lake, where the contamination was relatively lower. These data suggest that lakes in Kyonggi-Do province could be contaminated with EDCs and be subjected to the routine monitoring and water quality control.

• Economic and Environmental Geology
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• v.29 no.3
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• pp.305-313
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• 1996

In order to investigate the extent and degree of Cd, Cu, Pb and Zn contamination affected by mining activities of the Dalsung Cu~W mine, sampling of stream sediments and waters has been undertaken up to 1.5 km downstream from the mine at 50~150 meter intervals. Analysis of the samples was carried out using ICP-AES for Cd, Cu, Pb and Zn. Physical and chemical properties of sediments (pH, organic matter contents, cation exchange capacity) and waters (pH, Eh and temperature) were also measured. The properties of the sediment samples were characterized by low pH (3.0~5.5), low organic matter contents (2~5%) and a moderate degree of cation exchange capacity (7~15 meq/100 g) with a high proportion of sand fraction. The pH values of water samples ranged from 3.0 to 5.0 and the Eh levels were in the range of 350~530 mV. Concentrations of Cd, Cu, Pb and Zn in the sediments averaged 3.2 mg/kg, 1,390 mg/kg, 451 mg/kg and 262 mg/kg with the range of 0.6~11.4 mg/kg, 15~3,800 mg/kg, 14~1,330 mg/kg and 63~1,060 mg/kg, respectively. Significant levels of the heavy metals were also found in the water samples with the range of $10{\sim}170{\mu}gCd/l$, $300{\sim}41,600{\mu}gCu/l$, $10{\sim}80{\mu}gPb/l$ and $700{\sim}15,400{\mu}gZn/l$. These elevated concentrations in the sediments and waters may be caused by the weathering of mine waste materials and their high solubilities under acidic and/or oxidizing conditions. Although metal concentrations in the samples decrease with the distance from the mine, heavy metal contamination of sediments and waters were also found at the 1.5 km downstream due to the mobile conditions of the heavy metals, with particular reference to Cd and Zn in stream waters.