• Transactions of the Korean hydrogen and new energy society
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• v.24 no.4
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• pp.288-294
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• 2013

This gas analysis data come from the hydrogen which is produced by proton exchange membrane. Main impurities of hydrogen are methane, oxygen, nitrogen, carbon monoxide, and carbon dioxide. The concentration of impurities is ranged between 0.0191 to $315{\mu}mol/mol$ for each impurity. Methane contamination is believed from the electrode reaction between carbon doped electrode and produced hydrogen. Nitrogen contamination should take place the sampling process error, not from PEM hydrogen Production system.

• Korean Journal of Remote Sensing
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• v.5 no.2
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• pp.109-122
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• 1989

The ISODATA method, which is one of the most famous of the square-error clustering methos, has been applied to two Chungju multivariate data sets in order to evaluate the effectiveness of the regional lithological mapping. One is an airborne radiometric data set and the other is a mixed data set of the airborne radiometric and Landsat TM data. In both cases, the classification of the Bulguksa granite and the Kyemyongsan biotite-quartz gneiss are the most successful. Hyangsanni dolomitic limestone and neighboring Daehyangsan quartzite are also classified by their typical lowness of the radioactive intensities, though it is still confused with some others such as water-covered areas and nearby alluvials, and unaltered limestone areas. Topographically rugged valleys are also classified as the same cluster as above. This could be due to unavoidable variations of flight height and the attitude of the airborne system in such rugged terrains. The regional geological mapping of sedimentary rock units of the Ockchun System is in general confused. This might be due to similarities between different sediments. Considarable discrepancies occurred in mapping some lithological boundaries might also be due to secondary effects such as contamination or smoothing in digitizing process. Further study should be continued in the variable selection scheme as no absolutely superior method claims to exist yet since it seems somewhat to be rather data dependent. Study could also be made on the data preprocessing in order to reduce the erratic effects as mentioned above, and thus hoprfully draw much better result in regional geological mapping.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.110-113
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• 2002

Statistical- based, principal component analysis (PCA) was applied to chemical data from two underground storage systems containing LPG to assess the usefulness of such technique at the initial stage (Pyeongtaek) or middle stage (Ulsan) of hydrochemical studies. For the first case, both natural and anthropogenic contamination characterize regional groundwater. Saline water buffered by Namyang lake affects as a natural factor, whereas cement grouting influence as an artificial factor. For the second study area, contaminations due to operation of LPG caverns, such as disinfection activity and cement grouting effect, deteriorate groundwater quality. This study indicates that principal component analysis would be particularly useful for summarizing large data set for the purpose of subsurface characterization, assessing their vulnerability to contamination and protecting recharge zones.

• Journal of Food Hygiene and Safety
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• v.29 no.4
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• pp.322-326
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• 2014

According to Centers for Disease Control and Prevention (CDC, USA) recently it was reported that the children (< 5 year-old children) were more susceptible to Foodborne-illness. Confectionery products should be strictly controlled because they are children-preferred foods. Ministry of Food and Drug Safety (MFDS, South of Korea) tried to monitor contamination of organisms in confectionery products (such as biscuits, candies, chewing gums and ice candies) distributed in South Korea. MFDS evaluated the levels of indicator organisms: total aerobic bacteria, coliforms, Escherichia coli as well as the levels of food-borne illness organisms: Staphylococcus aureus, Bacillus cereus, Clostridium perfringens. Experimental plans for microbiological test were in accordance with the International Commission on Microbiological Specifications for Food (ICMSF). For this study, 1,005 samples were collected and from Seoul and Gyeongin region, South Korea. The average level of total aerobic bacteria in 1,005 samples was 1.7 log Colony Forming Unit(CFU)/g and the detection rate was 26.8%. The average level of Bacillus cereus was detected in 1.7 log CFU/g and the rate was 0.9%. There was no detection of coliforms, Escherichia coli, Staphylococcus aureus and Clostridium perfringens. The results of this study will be provided as the basic data to set the reasonable microbiological criteria of Korea Food Code.

• Journal of Environmental Health Sciences
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• v.8 no.1
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• pp.31-43
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• 1982

Seventy-seven Mugil cephalus of spinal deformation, living in Hanam, Nogsan, and Myeongji area, the downstreams of the Nagdong River, were collected in order to determine their forms and the levels of heavy metal contamination between March and October, 1981. The specimens were examined by X-ray and content of cadmium, lead, copper, and zinc by atomic absorption spectrophotometer. The results were summarized as follows: 1. The rate of appearance of deformational fish to the total Mugil cephflus were 4.3% (13 fish), 5.7% (17 fish), relatively high in May and June (dry season). Meanwhile during March and October they were low by 1.0% (3 fish), 2.0% (6 fish). As far as the research areas are concerned, they appeared in larger numbers in downstreams than in upper streams Myeongji (39), Nogsan (25), and Hanam (13). 2. Concerning with fractured parts of vertebraes,86 percent (66 out of 77) had their caudal regions fractured and 72 percent (55) their first to seventh caudal regions fractured. 3. The average levels of cadmium, lead, copper, zinc detected from flesh were 0.26ppm, 2.06ppm, 6.35ppm, 0.85ppm on the other hand, they were 0.22ppm, 1.84ppm, 5.03ppm, 0.93ppm in normal fish. 4. The average levels of cadmium, lead, copper, zinc measured in the bones were 0.39ppm, 2.55ppm, 8.97ppm, 2.73ppm. Meanwhile, from normal fish they were 0.33ppm, 2.25ppm, 7.24ppm, 2.42ppm. 5. Compared with regional heavy metal contamination such as cadium, lead, zinc, Myeongji area had higher contamination content than Nogsan area Nogsan area than Hanam area. 6. Compared with heavy metal contamination level in their tissues, cadmium was highly found in bones Lead and copper were highly detected in viscera. Particularly in skeleton cadmium was 560 times, zinc 160 times in proportion to those in the downstreams of the Nagdong River.

• Korean Journal of Food Science and Technology
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• v.43 no.1
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• pp.39-44
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• 2011

This study was carried out to examine microbiological contamination of ready-to-eat products and to propose a draft-standard and specifications according to food types. RTE foods were classified into 6 groups including fish products, meat products, breads, rices, salads, and fresh cut foods. The prevalence rates of pathogens detected from all samples were compared among food categories. The pH ranges for all RTE samples were between 3.8 and 7.3. Total aerobic cell counts ranged from 2 to 6 log CFU/g. Bread, rice and fresh-cut foods showed significantly higher counts, which ranged above 4.0 log CFU/g among the samples. Two kinds of rice were above the level of the KFDA Food Code standard for Eschrichia coli. The prevalence rate of E. coli in the rice was 6.7%. For Staphylococcus aureus, one fish product and one bread-product had levels above 2 log CFU/g. Bacillus cereus counts for all samples were below the level of 3 log CFU/g. Listeria monocytogenes was not detected in the samples. Therefore, these data suggest that the primary microbial hazard factors for ready-to-eat foods and risk assessments should focus on E. coli, S. aureus, and B. cereus.

• Korean Journal of Food Science and Technology
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• v.38 no.5
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• pp.605-608
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• 2006

Genetically modified (GM) ingredients found in imported raw materials and processed foods were monitored in the province Gyeongin in Korea. The analysis was performed according to "Testing methods for genetically modified foods of food standards and specifications" established in Korea. We received 120 items from the Gyeongin Regional KFDA. Only two of the 120 items analyzed in the samples, were contaminated with GM ingredients. However, we could not analyze the internal standard gene from 12 processed foods. We found that the extracted total DNA of the above 12 samples were extracted and found to be degraded. The total DNA contained a very small fragment of less than 300 base pair. Therefore, it seems that the total DNA is not large enough to serve as the template DNA for PCR analysis.

• Analytical Science and Technology
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• v.16 no.3
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• pp.232-239
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• 2003

The river sediments were collected from 4 points of Seoknam river, one point of Miho river and one point of the joining area of two rivers. For preparation of sample, three sediment samples were collected for the surface, middle and lower part of the sediment at each sampling point. The elemental concentrations were analyzed by neutron activation analysis using HANARO research reactor at Korea Atomic Energy Research Institute, and the concentrations of 30 elements were determined by the relative method using standard reference material of NIST. As a result of analysis, it was found that when the examination and prediction of contamination distribution about the site where the contamination site of river is connected to the lower river is done, the specific gravity of elements which is contained in the sediment and the speed of a current of river should be considered and also found that when the samples for concentration analysis in the river sediments are collected, for the establishment of regional representatives in samples, the range of sampling depth should be determined considering the specific gravity of elements and the speed of a current.

• Korean Journal of Food Science and Technology
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• v.39 no.5
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• pp.488-493
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• 2007

A survey for total aflatoxins (aflatoxins $B_1$, $B_2$, $G_1$, and $G_2$) was conducted on 245 cereals and processed cereal products, and 148 nuts and processed nut products in Korea, for a total of 393 commercialized ed samples. The total aflatoxins were quantified by the immunoaffinity column clean-up method with high performance liquid chromatography (HPLC) - fluorescence detection (FLD), and were confirmed by liquid chromatography tandem mass spectrometry (LC-MS/MS). Total aflatoxins(AFs) were detected in 37 samples (9.4% incidence), including 2 millet samples, 1 mixed cereal (sunsik), 1 powdered malt sample, 2 processed cereal products, 6 peanut samples, 22 peanut butter samples, and 1 sample each of almonds, adlay tea, and a processed nut product. The contamination levels were $0.04-2.65{\mu}g/kg$ for aflatoxin $B_1$, and $0.04-5.51{\mu}g/kg$ for total aflatoxins. Finally, LC-MS/MS analysis of the contaminated samples was conducted to confirm the detected aflatoxins, and all 37 samples showing aflatoxins by HPLC-FLD were confirmed by LC-MS/MS.

• Journal of Korean Tunnelling and Underground Space Association
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• v.5 no.1
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• pp.71-88
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• 2003

The DRASTIC system is widely used for assessing regional groundwater pollution susceptibility by using hydrogeological factors such as depth to water, net recharge, aquifer media, soil media, topography, vadose zone media, hydraulic conductivity. This study is providing Modified Drastic Model to which lineament density, land use, influence of groundwater drawdown caused by tunnel excavation are added as additional factors using geographic information system, and then to evaluate groundwater contamination potential of ${\bigcirc}{\bigcirc}$ area. For statistical analysis, vector coverage per each factor is converted to grid layer and after each correlation coefficient between factors, covariance, variance, eigenvalue and eigenvector by principal component analysis of 3 direction, are calculated, correlation between factors is analyzed. Also after correlation coefficients between general DRASTIC layer and rated lineament density layer, between general DRASTIC layer and rated land use layer, between general DRASTIC layer and rated tunnel excavation influence layer are calculated, final modified DRASTIC model is constructed by using them with each weighting. When modified DRASTIC model was compared with general DRASTIC model, contamination potential in modified DRASTIC model is fairly detailed and consequently, vulnerable area which has high contamination potential could be presented concretly.