• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.27-33
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• 2014

The significance of soil environment is gradually increased due to the soil and underwater contamination caused by petroleum leak accidents. It requires a high cost and long period for the purification of soil compared with other environmental matrix such as water and air. For this reason, it has been embroiled in a legal conflict to find the pollution source and charge of cleanup. In this study, we analyzed the physical properties and typical additives of jet fuel to search a method that can distinguish kerosene and jet fuel contamination. In particular, the chemical marker in kerosene was visualized by the developer and the additives in jet fuel, such as antioxidant and metal deactivator were detected by GC-MS. This study could be used to judge petroleum source at soil contaminant accident sites.

• Journal of Food Hygiene and Safety
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• v.16 no.3
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• pp.200-205
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• 2001

In this study, occurrence of aflatoxin M$_1$(AEM$_1$) in domestic milk and milk products was determined. The level of AFM$_1$ in market milk (0.047 ppb) was lower than that in raw milk (0.083 pub) but this looks like that is due to dilution in collecting process rather than the effect of sterilization. In the case of nonfat dry milk, level of AFM$_1$appeared high by 0.24 ppb but it is thought to be not different from market milk actually because nonfat dry milk is diluted at intake. In the case of ice cream, finished products were contaminated with AFM$_1$of 0.020 ppd and also have the possibility of the contamination of AFB$_1$due to secondary raw material such as nuts and almond. On the basis of the results of this study and previous studies, Monte-Carlo simulation is conducted to estimate the contamination level of AFM$_1$in domestic market milk. To consider uncertainty and variability fitting procedure was passed through. And we used beta distribution to estimate the prevalence and triangular distribution to estimate the concentration level of AFM$_1$in milk. As a result, the 5%, 50% and 95% points of the distribution of the probability of AFM$_1$contamination level in milk is 0.0214, 0.0946 and 0.1888 ppb, respectively. Also we estimate that AFM$_1$in almost milk was low more than 0.5 ppb that is American acceptable level but 80.4% exceeded far 0.05 ppb that is European standard.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.4
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• pp.182-189
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• 2001

In this paper, the distribution suspension porecelain insulators which had been used for long periods in the contaminated area were evaluated. The contaminated area is close to the sea and in the high density of industries. The heavily contaminated domestic and imported insulators were investigated by using electrical characteristics, such as power-frequency dry flashover voltage, power-frequency wet, flahover voltage, and leakage current. Also, these electrical results were compared with the contaminants on the surface. From these analysis, we found that the contamination from the industrial dust, only slightly decreased flashover voltage and increased leakage current. Therefore, the electrical properties of insulators used for 30 years in the area of coast and industrial complex were not much changed.

• Economic and Environmental Geology
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• v.53 no.2
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• pp.133-145
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• 2020

Soil in mine waste-rock fields, and at the pithead, sediments and farmlands around an abandoned mine in the Chungcheong Province of South Korea were investigated to assess the distribution of metallic elements and to understand the scope of the pollution. Reddening was observed from the mine up to a distance of 61 m. Losses of waste rock around the mine were assessed over a section of 1800 ㎥. Yellowish precipitates on the bottom of a stream were identified as ferrihydrite and goethite. For anions, a mean sulfate ion level over 773.6 mg/L was found during August in the river water samples. Mine drainage at the site was shown to have a pH of 4.9 and a sulfate concentration of 1557.8 mg/L during the August rainy season. A possible cause of the metallic element contamination in the mine is waste-rock loss, because mine waste-rock is located on the slope in this area. In conclusion, the total soil area to be treated, based on the amount that exceeded the recommended Korean soil pollution levels, was assessed to be 10,297 ㎡.

• 한국기계연구소 소보
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• s.19
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• pp.31-42
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• 1989

To investigate design factors of dilution ventilation system, numerical analysis of air contamination flow and concentration distribution have been made, by using the low Reynolds number turbulent model. And flow visualization and measurement of particle concentration for that model also have been made. By comparing of these results we have secured the essential data for the adequate counterplan of dilution ventilation system. The results of this study are as follows: 1) Inlet should be located near the wall for the prevention of the formation of the recircula¬tion zone. 2) In case of natural exhaust, air contamination flow is driven to the far outlet from the inlet. 3) It is favorable for dilution to make turbuence as much as possible.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.774-777
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• 1988

This paper covers the insulation coordination of 765 KV transmission line in Korea Electric Power Corporation. The design for the lightning, switching surge, and contamination was conducted to increase the reliability of 765 KV line. The authors have used the result of a limited Westinghouse ANACOM swiching surge study of the Korea Electric Corporation's 765 KV Expansion plan. The study investigated the switching surge overvoltage distribution and maximum switching overvoltage when relosing 765 KV lines. They used the technical data of the suspension insulator for the contamination design, which was available from a foreign insulator manufacture. From this paper, the authors find out that the contamination design dominates to determine the number of insulator and the SOV design dominates the air clearance in the tower. Afterwards the authors will confirm this design by Demonstration Test with Korea Electro-technology Research Institute.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.767-770
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• 2000

This study was investigated for searching a cause of flashover failure of polymer insulator and preparing countermeasures. Hydrophobicity, microstructure and chemical structural change of polymer weathershed were studied by polymer characterization methods. In addition, the electrical properties such as power frequency dry flashover voltage/impulse voltage tests, contamination characteristics were carried out. The hydrophobicity of polymer weathershed was decreased significantly and cracks were observed on the surface. Also, the electrical characteristics did not satisfy the KEPCO specification. The failed polymer insulators showed the more leakage current than 4 years service-aged ones. From the result, it can be concluded that the flashover failure of polymer insulator was attributed to the surface aging and severe contamination.

• Bulletin of Food Technology
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• v.24 no.4
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• pp.640-646
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• 2011

• Journal of Soil and Groundwater Environment
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• v.19 no.6
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• pp.59-71
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• 2014

We investigated soil contamination depending on the land use by examining the contamination levels and distribution characteristics of 16 polycyclic aromatic hydrocarbons (PAHs) in the national soil. Total PAHs (the sum of 16 PAH concentrations) and carcinogenic PAHs (the sum of seven carcinogenic PAH concentrations) were $8.50{\sim}3,437.16{\mu}g/kg$ and $2.94{\sim}2,136.96{\mu}g/kg$, respectively. The concentration of benzo(a)pyrene, one of the contaminants regulated by the soil quality standard in the nation, was $ND{\sim}924.73{\mu}g/kg$. Its maximum value of $924.73{\mu}g/kg$ was detected in railroad (Region 3) and is approximately 13% of the standard value for Region 3 (i.e., 7 mg/kg). We also investigated the characteristics of contamination sources of PAHs in soil of the upland, forests, roads, and railroads, examining the fraction distribution of PAHs concentration by the number of benzene rings against the total PAHs concentration. The results demonstrate that the mean fraction of 4~6-ring PAHs against total PAHs concentration in soil was in the range of 51.8~80.7% with relative abundance of high-molecular PAHs, showing that the origin of contamination is under the category of combustion sources. When the molecular indices (Flu/(Flu/Pyr), Ant/(Ant+Phe), InP/(InP+BP), and BaA/(BaA+Chr)) were applied, they were also categorized as petroleum-based combustion sources. The individual PAH concentrations in soil by the land use were grouped into Regions 1, 2, and 3, which are statistically treated and are the parts of the national category system of soil quality standard. As a result, the concentration level of 16 PAHs was $0.02{\sim}2.63{\mu}g/kg$ in Region 1, $0.05{\sim}4.26{\mu}g/kg$ in Region 2, and $2.36{\sim}178.27{\mu}g/kg$ in Region 3. The concentration level of 6 carcinogenic PAHs was 14.2~320.4% against that of benzo(a)pyrene in Region 3 and sites of recycling waste sleepers. Considering that there were similarities among PAHs in terms of structures and toxicities, it would be recommended to review other types of carcinogenic PAHs together with benzo(a)pyrene when developing the soil quality standards in the nation.

• Journal of Digital Convergence
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• v.11 no.12
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• pp.665-672
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• 2013

In radiology department, where patients with a variety of diseases receive their tests, there is a large possibility of cross contamination of nosocomial infection. Magnetic resonance imaging (MRI) tests take particularly more time than other tests do, which increases the possibility of being exposed to cross contamination. Therefore, this research examines the status of MRI equipment sterilization and investigates the bacterial distribution on head coils, which have the most frequent contact with patients, patient fixation blocks, and bores, which are confined spaces. The status of MRI equipment disinfection was examined by a survey targeting 150 employees, and the distribution of bacteria was measured in ten medical facilities. The result of bacterial distribution tests on MRI equipment showed various bacteria, including Staphylococcus, Acinetobacter, Sphingomona, Pantoea agglomeranss, Micrococcus, Bacillus, Saprophyticus, Brevundimona, and Myroidesspecies. The result of examining the stat us of MRI room disinfection showed that the disinfections of the head coil, block, and bore were implemented well, and the largest proportion was carried out once a day in the morning. The time and implementation of disinfection by the disinfection manager showed that they were implemented well when the manager was the MRI room examiner. The disinfection after examining a patient using an appropriate disinfectant is mandatory to prevent cross contamination.