• The Journal of Korean Academy of Prosthodontics
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• v.31 no.1
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• pp.11-18
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• 1993

Autopolymerising and visible light cured resin are used to reline dentures. But relined surface are easily contaminated by water or saliva in the mouth during clinical procedure. This study was to find out the effect of surface contamination on the transverse strength of the relined denture base. To accomplish this, the specimens of $65\times10\times3mm$ were made with heat-cured(Lucitone 199), visible light-cured(Triad), and autopolymerizing resin(Kooliner). Measurements of transverse strength were taken for each specimen. Specimens made of heat-cured resins, sizing $65\times10\times1.5mm$, were relined with heat-cured, light-cured, and autopolymerizing resin, respectively. Specimens relined with autopolymerizing and light-cured resins were further classified into not-contaminated, water-contaminated and saliva-contaminated groups. Again, measurements of the transverse strength were taken for each group. The results were as follows 1. The transverse strength of heat-cured resin was superior to all the other resins. 2. The transverse strength of each specimen decreased after relining in the following order, heat-cured, visible light-cured, and autopolymerizing resin. 3. Surface contamination produced an decrease in transverse strength, especially in the saliva contaminated group. According to these results, water or saliva contamination should be avoided during intraoral relining procedures.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.5
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• pp.650-658
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• 2000

This study was investigated to compare the bond strength of polysulfide adhesive between tray resin and border molding materials and to evaluate the effect of saliva contamination on them. We made the 135 resin tray secimens with a dimension of $1{\times}1{\times}1cm$ and divided them into 3 groups by the materials 1) Quicky group, 2) Compound group, and 3) Impregum group Each group was subdivided by saliva contimination. Group S1 : applied adhesive without saliva contamination Group S2 : applied adhesive after drying 15seconds after saliva contamination Group S3 : applied adhesive no after saliva contamination. Tensile tests were performed with a Universal Load testing machine. Results showed Impregum group significantly higher bond strength than Quicky group, but there was no significant difference in adhesive bond strength between Compound group and Quicky group in experimental group by materials In experimental group by saliva contamination, S1 group is significantly higher bond strength than S2 group and S2 group is significantly higher bond strength than S3 group in Quicky group and S1, S2 group is significantly higher bond strength than S3 group in Compound group and Impregum group. Impression compound and Impregum F which are usually used as an individual tray border mold-ing material can be said to be satisfied in adhesive bond strength to polysulfide impression materials. After try-in and clinical adjustment are performed, a custom tray should be properly rinsed and air dried before tray adhesive was placed.

• Journal of Environmental Health Sciences
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• v.46 no.5
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• pp.548-554
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• 2020

Objectives: This study is to examine the polyvinyl chloride (PVC) materials in elementary school classrooms and libraries in Seoul, and to investigate phthalate contamination in indoor dust. Methods: PVC material was identified for building materials and furniture using portable x-ray fluorescence (XRF). Phthalates in dust samples (n=19) were extracted by ultrasonic extraction using cyclohexane and analyzed by GC-MS. Results: Diethyl phthalate (DEP), di-n-butyl phthalate (DBP), and Bis (2-ethylhexyl) phthalate (DEHP) were found in all collected dust samples (n=19), and diisonyl phthalate (DINP) was detected in all except for one sample (n=18). The concentration of DEHP (median: 2190 mg/kg) and DINP (2960 mg/kg) were higher than other compounds, suggesting that there are many products in the school that used these compounds. When comparing the phthalate concentration in the classroom (n=11) and library dust (n=8), the total concentration in the classroom (median: 10000 mg/kg) was higher than that in the library (8030 mg/kg). DEHP was the dominant compound in the library. The library is relatively more equipped with PVC furniture (n=83) and most floors are also identified as PVC material, suggesting that floors and furniture made of PVC materials are main sources of DEHP contamination. Conclusions: This study is a pilot survey for investigating phthalate contamination in elementary schools. As a result of the survey, phthalate contamination in elementary school was confirmed. However, further study requires risk assessment of children through analysis of phthalate metabolites in children based on sufficient number of samples and information about the site.

• Journal of Animal Science and Technology
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• v.47 no.3
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• pp.481-490
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• 2005

Nitrate contamination in water system is a critical environmental problem caused by excessive application of chemical fertilizer and concentration of livestock. In order to prevent further contamination, therefore, it is necessary to understand the origin of nitrate in nitrogen loading sources and manage the very source of contamination. The objective of this study was to examine the nitrate contamination sources in different agricultural system by using nitrogen isotope ratios. Groundwater and runoff water samples were collected on a monthly basis from February 2003 to November 2003 and analyzed for nitrogen isotopes. The nitrate concentrations of groundwater in livestock fanning area were higher than those in conventional and organic fanning area and exceeded the national drinking water standard of 10mg N/ l. The ${\delta}^{15}N$ranges of chemical fertilizer and animal manure were - 3.7${\sim}$+2.3$\textperthousand$ and +12.5${\sim}$26.7$\textperthousand$, respectively. The higher ${\delta}^{15}N$ of animal manure than those of chemical fertilizer reflected isotope fractionation and volatilization of '''N. The different agricultural systems and corresponding average nitrate concentrations and ${\delta}^{15}N$ values were: conventional farming, 5.47mg/e, 8.3$\textperthousand$; organic fanning, 5.88mg/e, 10.1$\textperthousand$; crop-livestock farming, 12.5mg/e, 17.7%0. These data indicated that whether conventional or organic agriculture effected groundwater and runoff water quality. In conclusions, relationship between nitrate concentrations and ${\delta}^{15}N$ value could be used to make a distinction between nitrate derived from chemical fertilizer and from animal manure. Additional investigation is required to monitor long-term impact on water quality in accordance with agricultural systems.

• Korean Journal of Clinical Laboratory Science
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• v.48 no.3
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• pp.237-241
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• 2016

This study, funded by Jeju Special Self-Governing Province, evaluated the bacterial contamination in disposable wet wipes used in restaurants, coffee shops, and bakery shops. The materials used are 55 disposable wet wipes collected from general restaurants. The number of average bacteria found was $4.21{\times}10^3CFU/mL$ in 50 disposable wet wipes; in the other five disposable wet wipes, no bacterial contamination was found. The highest number of bacteria was measured as $16.67{\times}10^3CFU/mL$. Total bacterial count of separated are 71 strains. Among the 71 identified strains, 15 were Staphylococcus aureus and 3 were Pseudomonas aeruginosa. This can be an important problem. This study measured the level of bacterial contamination and identified the strains isolated in wet wipes. This study may be important as it provides the basis for establishing sanitation standars for wet wipes.

• Journal of the Korean Society of Radiology
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• v.7 no.3
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• pp.221-225
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• 2013

The purpose of this study was to examine the impact of the Fukushima nuclear power plant accident of Japan in 2011 on kindergarten teachers' perception on young children's safety due to radioactive contamination. This study analysed the 134 questionnaire forms out of 197 kindergarten teachers in the region of Chungbuk. The findings of the study indicated that the Japanese unclear power plant accident exerted an influence on anxious of kindergarten teachers on young children's safety due to radioactive contamination. In conclusion, kindergarten teacher education are required to improve the safety knowledge of kindergarten teachers and alternative resolution method for young children's safety due to radioactive contamination.

• Korean Journal of Microbiology
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• v.1 no.1
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• pp.48-50
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• 1963

The authors have investigated about the microbial contamination of goods which is a criterion of hygienic control. Conducting on investigation, a special attention has been paid on the rate of microbial contamination in the goods, especially in manufacturing process of the softdrink. The authors also made an experiment on total microbes which is the criterion of contamination in each step of the process and in raw materials together with materials to be used for subdividing. Results obtained were as follows : 1) The orgin of microbial contamination was found in bottle cap and in tap water, that is, there appeared 9 colony per ml in bottle cap and 31-74 colony per ml in tap water, respectively. 2) It was found that microbial contamination are 4 colony per ml in average through year. However, it appeared 1 colony per ml in winter and 8 colony per ml in summer. 3) Coliform groups are not detected in goods through a year. 4) There was no variation in number of total microbes after ion exchange resin passage in purification process of tap water. 5) The number of microbes in goods are decreased when the raw materials are treated in high temperature short time (HTST) sterilization.

• Journal of Environmental Health Sciences
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• v.39 no.5
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• pp.426-437
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• 2013

Objective: Gotjawal refers to a special geographical designation found in Jeju Province, Korea, where vegetation forms over a rocky area. Due to the important ecological value of Gotjawal, international concern about such areas is growing. However, only limited information is available regarding environmental contamination of Gotjawal. This study was conducted in order to investigate the levels of contamination and associated ecotoxicological effects of surface water bodies in Gotjawal. Methods: Surface water samples were collected at three sampling sites in two Gotjawal areas and were analyzed for several pharmaceuticals and pesticides in consideration of the potential sources of contamination. The ecotoxicity of the samples was measured using water fleas (Daphnia magna and Moina macrocopa) and zebrafish (Danio rerio). In addition, effects on the gene transcription of zebrafish were investigated following exposure to the samples. Results: Nine pharmaceuticals were detected in the samples, but none of the target pesticides were detected. Following acute exposure to two surface water samples, the survival of waterfleas was significantly reduced, but reproduction was not affected. In zebrafish, time-to-hatch was delayed and fry survival was decreased in some samples. On the other hand, at the transcriptional level, there were no genes significantly influenced by exposure to the samples. Conclusion: This is the first study investigating environmental contamination in Gotjawal areas and associated ecotoxicities. Further studies are warranted to identify the cause of acute Daphnia toxicity and to determine potential consequences of longer-term exposure in Gotjawal areas.

• Korean Institute of Interior Design Journal
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• v.20 no.3
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• pp.182-189
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• 2011

This research suggests a way of hygienic space planing of the customer space in the university student restaurant of E University in Seoul. For this study. the behavior observation in the restaurant was conducted in order to analyze the sequence of customer behavior related space planing applying HACCP (Hazard Analysis And Critical Control Point). Also the survey was conducted to analyze opinions of customers about hygiene of the space. The results of the analyses of the observation and the survey were similar in terms of hygiene. In conclusion, for hygienic space planing of the customer space in restaurant, the space circulation should be planned according to the hygienic sequence of customer behavior. The spaces in restaurant should be divided into two areas: the clean area and the contaminated area to prevent cross-contamination. The clean area, such as spaces preparing dishes and food including water and table hall where customers eat, should be separated from the contaminated area such as the spaces where waste is handled and where dirty dishes are kept. In order to prevent cross-contamination, hygiene facility to remove contamination should be located before going to the clean area. More specifically, the hygiene facility should be located between a cash counter and a space preparing dishes so that customers can wash their hands before they touch dishes. Space arrangement with feed-back process to check the possible points of cross-contamination and correct space arrangement until the possibility of cross-contamination is removed in the restaurant.

• Journal of the Korean Society for Marine Environment & Energy
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• v.1 no.1
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• pp.83-92
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• 1998

Heavy metals concentration in superficial sediment of effluent discharging area was rapidly increased by annual loadings of Zn(8.465 Kg), Ni(3,291 Kg), Cu(1,636 Kg) and Pb(1,250 Kg) from sewage effluent of 63×10/sup 6/ m³/yr. In a consequent result, specially the concentrations of Zn and Cu in the sediment were three times higher than preindustrial reference values. The evaluation by multiple ecological risk indices showed that heavy metals contamination in sediment of discharging area was 'heavily Polluted level' by sediment quality criteria and increased 2.6 times by the degree of contamination. It was also judged that toxicological effects of sediment receiving the primary effluent would occasionally (16～47%) occur by guidelines for adverse biological effect.