• The Journal of the Convergence on Culture Technology
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• v.9 no.2
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• pp.561-568
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• 2023

Various defects occur in concrete structures due to internal and external environments. If there is a defect, it is important to efficiently identify and maintain it because there is a problem with the structural safety of concrete. However, recent deep learning research has focused on cracks in concrete, and studies on exfoliation and contamination are lacking. In this study, focusing on exfoliation and contamination, which are difficult to label, four models were developed and their performance evaluated through unlabelling method, filtering method, the convergence of transfer learning based k-means clustering. As a result of the analysis, the convergence model classified the defects in the most detail and could increase the efficiency compared to direct labeling. It is hoped that the results of this study will contribute to the development of deep learning models for various types of defects that are difficult to label in the future.

• Korean Journal of Microbiology
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• v.49 no.4
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• pp.424-428
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• 2013

To identify risk factors for Legionella contamination, water quality variables routinely measured in examination of natural and city waters were meta-analyzed for significance of correlation to Legionella incidences. For evaluation of abundance of Escherichia coli as a risk factor, which is currently used as an indicator of Legionella contamination in an official guideline in Korea, odds ratio (OR) of above-cutoff total coliform counts for Legionella presence/absence was used as the effect size in the meta-analysis. The OR was estimated as 1.05 (0.36-3.12, 95% CI), and the probability of having identical odds reached 0.92. Also, ORs from individual studies showed significant heterogeneity (P=0.008), which contributed to 63% of total variance of the ORs. In the case of heterotrophic plate count (HPC), the OR for Legionella presence/absence was 2.72 (2.04-3.63) with highly significant deviation from identical odds (P<0.0001). ORs from different studies were seemingly homogeneous ($Q_{df=8}$=12.7, P=0.12). Turbidity and concentrations of chlorine, iron ion and cupper ion were other routine variables that could be considered as risk factors. However, statistical measures from different studies were not uniform enough to develop an appropriate effect size while the number of studies reporting the variables was also small (3-5). In conclusion, HPC appeared to be appropriate as indicator of Legionella contamination, rather than fecal bacteria contamination. HPC may imply abundance of habitats (amoebas and biofilms) of Legionella in water. This result warrants further studies for standardizing protocols and cutoff values to infer Legionella risks from HPC.

• Journal of Soil and Groundwater Environment
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• v.8 no.2
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• pp.9-18
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• 2003

Sampling of waters from each stage of treatment system (Successive Alkalinity Producing System; SAPS), tailings seepage, and spring near the Hanchang coal mine of Kangwon Province were carried out seasonally and analyzed to evaluate the source and possible path of groundwater contamination by acid mine drainage (AM). Sulfur isotope compositions were measured to identify the origin of groundwater contaminations and the sulfate reduction processes in the SAPS. Low pH and high metal concentration of spring water indicates possibility of the groundwater contamination by AMD. Removal efficiency of acidity of the SAPS was 18.17 g/$\textrm{m}^2$/day on an average and the metal removal efficiency was almost 100%, which was higher than those of other treatment systems. However, no appreciable decrease of sulfur content and almost similar sulfur isotope compositions of water from each stage of the treatment system may suggest incomplete or very poor sulfate reduction by sulfate reducing bacteria. Chemical and sulfur isotope compositions showed that spring water was contaminated by seepage from mine tailings. And seepage of stonewall, a part of treatment system was affected by both tailings seepage and mine adit drainage. In this study site, the treatment system was constructed for the only AMD from mine adit not for tailings seepages, which resulted in the groundwater contamination from tailing seepages. Similar situation is expected in other abandoned coal mine areas.

• Korean Journal of Microbiology
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• v.46 no.2
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• pp.152-156
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• 2010

Disposable contact lenses, which are one type of soft contact lenses, provide convenience in use, but also cause various ocular infectious diseases. Microorganisms that cause eye diseases include Acanthamoeba, bacteria, Fungi, and so on. It is impossible to prevent microorganism contamination completely due to the use of hands as wearing contact lenses. The contamination by various microorganisms leads to infectious keratitis, but it is not well known for the exact microorganisms that affect the disease. For this reason, to identify the microorganisms, two groups that are commonly used for disinfection of lenses were divided: normal saline solution and multiple purpose solution. Using these solutions the degree of microorganism contamination was observed according to the days of 1, 3, 5, 10, and 15. Twenty students by two groups from Ophthalmic Optics department at D college in Daegu Metropolitan city participated in the experiment after their ocular health conditions were checked. During they wore one-day disposable lenses for 1, 3, 5, 10, and 15 days, bacteria were cultured in media. The results, which were Gram stained by selecting the cultured colonies, show as followings: Gram positive cocci 33%, Gram-negative cocci 2%, Gram positive bacilli 34%, and the Gram negative bacilli 31%, respectively. As for the identification of potential pathogens, VITEK system and API kit methods were used. Keratitis caused by bacteria known as Staphylococcus aureus, Pseudomonas aeruginosa were detected as a result of wearing contact lenses. This study examined the distribution of bacteria as wearing one-day disposable contact lenses and pathogenic bacteria according to the duration of wearing them. In conclusion, the importance of hygiene when using contact lenses is suggested.

• Economic and Environmental Geology
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• v.55 no.6
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• pp.717-726
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• 2022

This study was conducted to assess the geochemical contamination degree of As, Cd, Cu, Pb, Sb, and Zn in the soil and water samples from an abandoned gold mine. Enrichment Factor (EF), Geoaccumulation Index (Igeo), and Pollution Load Index (PLI) were carried out to assess the geochemical contamination degree of the soil samples. Variations of sulfate and heavy metals concentration in water samples were determined to identify the geochemical distribution with respect to the distance from the mine tailing dam. Geochemical pollution indices indicated significant contaminated with As, Cd, Pb, and Zn in the soil samples that areas close to the mine tailing dam, while, Sb showed similar indices in all soil samples. These results indicated that the As, Cd, Pb, and Zn dispersion has occurred via anthropogenic sources, such as mining activities. In terms of water samples, anomalies in the concentrations of As, Cd, Zn, and SO₄^2- was determined at specific area, in addition, the concentrations of the elements gradually decreased with distance. This result implies the heavy metals distribution in water has carried out by the weathering of sulfide minerals in the mine tailing and soil. The study area has been conducted the remediation of contaminated soil in the past, however, the geochemical dispersion of heavy metals was supposed to be occurred from the potential contamination source. Therefore, continuous monitoring of the soil and water is necessary after the completion of remediation.

• Journal of Environmental Health Sciences
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• v.41 no.6
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• pp.397-404
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• 2015

Objectives: The aim of this study is to investigate microbial contamination in the school food service environment for the assessment of microbial food safety. Methods: We collected both swab samples from tables and desks and airborne bacterial samples from an elementary school (School A) and a high school (School B). Heterotrophic plate count, total coliform, Staphylococcus aureus, and Bacillus cereus were measured with selective media to quantify microbial concentration. PCR assay targeting 16S rRNA genes was performed to identify the strains of S. aureus and B. cereus isolated. In addition, we made a food service checklist for the locations to evaluate the food service environment. A Wilcoxon test was employed to examine the differences in microbial concentration between before lunchtime and afterwards. Results: Heterotrophic plate counts showed higher levels after-lunch compared to before-lunch at School B. However, levels of S. aureus were higher in the after-lunch period (p<0.05) in both classrooms and in the cafeteria in School A. B. cereus was only sparsely detected in School B. Several samples from food dining carts were found to be contaminated with bacteria, and facilities associated with food delivery were found to be vulnerable to bacterial contamination. Although microbial concentrations in the air showed little difference between before- and after-lunchtime in the cafeteria in School A, those in classrooms were greater after-lunchtime at both schools. Conclusion: Our results suggested that the microbial safety in schools after lunchtime of concern. Necessary preventive measures such as hygiene education for students and food handlers should be required to minimize microbial contamination during food service processes in schools.

• Economic and Environmental Geology
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• v.34 no.5
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• pp.485-498
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• 2001

This study was objected to identify the temporal and spatial variations oi groundwater quality and contamination using monthly groundwater monitoring data collected from 30 wells in Daejung watershed, Jeju Island. Water samples were analyzed for major cations. anions, and environmental isotopes including $^{18}0-H_2$O,$^{2}H-H_2$O and$^{15}$ N-NO$_3$The groundwater represented mostly Na(Mg)-HCO$_3$ type, with local change toward Ca-HCO$_3$ type and Na-Cl type. Groundwater quality depends upon various factors such as the local groundwater flowpaths, input of surface contaminants with recharge events, and sea-water intrusion along the coastal area. Nitrate contamination changed temporally according to recharge events and spatially. $\delta$$^{18}$ O-$\delta$$_2$H data for monthly sampled groundwaters showed distinctive clusters, implying that groundwater was originated from independent precipitation, and subsequently recharged very fash. Using$\delta$$^{15}$ N-NO$_3$ data, major sources of nitrate and its areas of influence could be identified. The areas under influence of livestock farms showed relatively high NO$_3$-N concentrations and$\delta$$^{15}$ N values higher than 5$\textperthousand$. The agricultural areas in southeastern part showed very high concentrations of NO$_3$-N with the $\delta$$^{15}$ N values of lower than 5$\textperthousand$.

• Journal of Applied Biological Chemistry
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• v.59 no.1
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• pp.63-68
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• 2016

This study was performed to assess the microbiological quality of Brassica campestris var. narinosa microgreen from harvesting and processing steps. The samples were analyzed for total viable cell counts (TVC), coliforms, Enterobacteriaceae, Escherichia coli, Salmonella spp., Listeria monocytogenes, Vibrio parahaemolyticus, Bacillus cereus, and Staphylococcus aureus. The total viable counts of microgreen (whole leaves) and environment samples from harvesting steps were higher than 6.8 log CFU/g and the contamination level of coliforms in the samples were 3.2 log CFU/g and 3.5 log CFU/g of microgreen and soil, respectively. In case of microgreen samples collected from processing steps, the contamination level of TVC and coliforms were higher in raw materials than samples obtained from later stages of processing, i.e. washing, drain, and final products. The contamination levels of B. cereus in raw materials and environments decreased approximately 1.4 log CFU/g in final products. S. aureus was detected in soil samples but Salmonella spp., Listeria monocytogenes, Vibrio parahaemolyticus and pathogenic E. coli was not detected. In order to identify the sources of contamination for microgreen, the genetic similarity of B. cereus isolates obtained from harvesting and processing steps were compared using the repetitive-sequence-based polymerase chain reaction method. B. cereus isolates obtained from harvesting environments and microgreen were clustered with a similarity greater than 95%. In case of B. cereus isolates obtained from microgreen and environmental samples at processing steps showed low genetic similarity.

• Journal of Environmental Health Sciences
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• v.37 no.5
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• pp.376-386
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• 2011

Objectives: The aim of this study was to evaluate the microbial hazards posed by food utensils and fixtures in food service operations at selected middle and high schools located in Seoul, Korea. Methods: We collected 200 samples of utensils and fixtures including cups, spoons/chopsticks, food trays and tables from five different schools in Seoul. Target microorganisms of this study were divided into two groups: total bacterial count and total coliform as indicators of microbial contamination and Bacillus cereus and Staphylococcus aureus as pathogens of food poisoning. We used selective media to quantify microbial concentration and 16S rRNA PCR assay for qualitative analysis. In addition, intensive interviews with nutritionists were conducted and observations were made to identify factors that may affect microbial contamination. Logistic regression analysis was employed to examine the relationship between the microbial concentration and operation characteristics of each operation. Results: The level of microbial concentration in school B and C were significantly lower than in school A, D and E (p<0.05). Some samples from school A, D and E showed over 3.4 log CFU/100 $cm^2$ (total bacterial count) and 1.0 log CFU/100 $cm^2$ (total coliform), which requires immediate hygienic action. The number of customers per staff member, periodicity of hygiene education for staff and daily operation time of sterilizers were also found to be important factors related with the microbial contamination of food service operations. Conclusions: These results suggested that not only a HACCP (Hazard Analysis and Critical Control Point) approach, but also efforts to assess internal risk factors within operations be needed to reduce the microbial contamination of food utensils and fixtures. This study is expected to provide preliminary data for assessing microbial hazards in food service operations.

• Parasites, Hosts and Diseases
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• v.55 no.5
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• pp.523-532
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• 2017

A field survey studying intestinal parasites in humans and microbial pathogen contamination at environment was performed in a Laotian rural village to identify potential risks for disease outbreaks. A parasitological investigation was conducted in Ban Lak Sip village, Luang Prabang, Lao PDR involving fecal samples from 305 inhabitants as well as water samples taken from 3 sites of the local stream. Water analysis indicated the presence of several enteric pathogens, i.e., Aeromonas spp., Vibrio spp., E. coli H7, E. coli O157: H7, verocytotoxin-producing E. coli (VTEC), Shigella spp., and enteric adenovirus. The level of microbial pathogens contamination was associated with human activity, with greater levels of contamination found at the downstream site compared to the site at the village and upstream, respectively. Regarding intestinal parasites, the prevalence of helminth and protozoan infections were 68.9% and 27.2%, respectively. Eight helminth taxa were identified in fecal samples, i.e., 2 tapeworm species (Taenia sp. and Hymenolepis diminuta), 1 trematode (Opisthorchis sp.), and 5 nematodes (Ascaris lumbricoides, Trichuris trichiura, Strongyloides stercoralis, trichostrongylids, and hookworms). Six species of intestinal protists were identified, i.e., Blastocystis hominis, Cyclospora spp., Endolimax nana, Entamoeba histolytica/E. dispar, Entamoeba coli, and Giardia lamblia. Questionnaires and interviews were also conducted to determine risk factors of infection. These analyses together with a prevailing infection level suggested that most of villagers were exposed to parasites in a similar degree due to limited socio-economic differences and sharing of similar practices. Limited access to effective public health facilities is also a significant contributing factor.