• Journal of dental hygiene science
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• v.18 no.5
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• pp.296-304
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• 2018

The purpose of this study was to propose a method for the effective management of toothbrush contamination. Toothbrush microbial contamination was analyzed according to the duration of toothbrush use, frequency of toothbrush use per day, and toothbrush storage location. We also analyzed the microbial reduction effect of vinegar, antimicrobial mouth rinse, bamboo salt, and baking soda, which are sterilization materials that can be easily used every day. We collected 45 toothbrushes from university dormitories from May to June 2018. To determine the degree of microbiological contamination with general bacteria, coliform bacteria, and Staphylococcus aureus, bristle samples were cultured at $36^{\circ}C$ for 24 hours using 3M$^{TM}$ Petrifilm plates and then measured based on Petrifilm evaluation criteria. Toothbrush microorganisms were analyzed according to the duration of use, frequency of use per day, storage location, and effect of each sterilization material. General bacteria, coliforms, and S. aureus contamination increased with frequency and duration of use (p<0.05). In particular, S. aureus showed a statistically significant increase to 36.15 CFU/ml after 1 month, 504.23 CFU/ml after 2 months, and 2,386.67 CFU/ml after 3 months (p<0.05). We found that 1% vinegar was the most effective substance for reducing general bacteria, coliforms, and S. aureus. In addition, 1% antimicrobial mouth rinse solution applied for 5 minutes was the most effective in reducing S. aureus. It is crucial to recognize the importance of toothbrush care and store toothbrushes in a dry place and replace them periodically. We recommend use of vinegar and antimicrobial mouth rinse solution to disinfect toothbrushes. These should be applied as a 1% solution for at least 1 minute. Proper care of toothbrushes is important in maintaining oral health as well as overall health. Instructions on toothbrush care should be given when teaching children or adults how to brush teeth.

• Journal of Soil and Groundwater Environment
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• v.18 no.3
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• pp.93-108
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• 2013

This study is aimed to prepare the effective detail survey methods(Phase II) of abandoned metal mines through the contamination assessment for mine types and facilities in the abandoned metal mine areas. The study sites of 12 abandoned mines are located in Gyeonggi-do and Gangwon-do and those were chosen among 310 sites that the Phase II survey was conducted from 2007 to 2009 after considering the results of Phase I for abandoned mines scattered all over the country. 12 study sites were classified into four types; Type I sites only have pit mouth. Type II sites have pit mouth and mine-waste field. Type III sites have pit mouth and tailing sorting field. Type IV sites have pit mouth, tailing sorting field and concentrator(s). In forest land, paddy soil and farm land of Type I, As and Cd were showed average concentration, and Cu and Pb were high on the pit mouth area in one mines where the pit mouth was developed within 500 m. In the mines of Type II, Cu and Pb were showed average concentration too, but As and Cd were slightly high in pit mouth and mine-waste field. The mines of Type III which had grinding particle process through physical separation milling or hitting showed similar tendency with Type II. However, mines of Type IV pit mouth, mine-waste field and showed various results depending on defining the contamination sources. For example, if contamination source was pit mouth, the mixed results of Type I, II, II were showed. In tailing sorting field which was regarded as the most important source and having high mobility, however, if there were no facilities or it was difficult to access directly, field sampling was missed occasionally during phase I and phase II survey. For that reason, the assessment for tailing sorting field is missed and it leads to completely different results. In the areas of Type I mines, the concentration of heavy metals exceeded precautionary standards of soil contamination or not within 1,000 meters of pit mouth. Nickel(Ni) was the largest factor of the heavy metal contamination in this type. The heavy metals except Arsenic(As) were shown high levels of concentration in Type II areas, where pit mouth and mine-waste field were operated for making powder in upriver region; therefore, to the areas in the vicinity of midstream and downstream, the high content of heavy metals were shown. The tendency of high level of heavy metals and toxic materials contained in flotation agent used during sorting process were found in soil around sorting and tailing field. In the abandoned-pit-mouth area, drygrinding area and tailing sorting field area, the content of Cupper(Cu) and Zinc(Zn) were higher than other areas. Also, the contaminated area were larger than mine reclamation area(2,000 m) and the location of tailing sorting field was one of the important factors to estimate contaminated area.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.12-24
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• 2023

With the improvement of laser technology, the strategic needs of efficient and precise decontamination of various components in nuclear application units can be fulfilled by laser decontamination. The surface contaminants of nuclear facilities mainly exist both as loose contaminated layer and fixed oxide layer. The types of radionuclides and contamination layer thickness are closely related to the operation status of nuclear facilities, which have an important influence on the laser decontamination process. This study reviewed the mechanism of laser surface treatment and the influence of laser process parameters on the decontamination thickness, decontamination factor, decontamination efficiency and the distribution of aerosol particle. Although multiple studies have been performed on the mechanism of laser processing and laser decontamination process, there are few studies on the microscopic process mechanism of laser decontamination and the influence of laser decontamination on surface properties. In particular, the interaction between laser and radioactive contaminants needs more research in the future.

• Progress in Superconductivity
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• v.4 no.2
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• pp.162-167
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• 2003

The critical current value of Bi-2223/Ag tape can be influenced by various factors. In particular, it was known that properties of precursor powders could affect the formation of Bi -2223 and grain growth rate of the same. Since, moistures and organic matters can easily contaminate the precursor powders of Bi-2223 tapes and degrade properties of superconductors, the precursor powders should be kept in optimal conditions to minimize contamination. In this study, the effect of moisture and organic matters has been investigated. A Bi-2223/Ag tape contaminated with a large amount of moisture and organic matter has been characterized by low critical current values and bubbling. It has been found that as the quantity of moisture increases, the Bi-2223 phases are formed at lower temperature and the amount of non-superconducting phase increases.

• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.773-780
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• 1996

Silicon oxide films were prepared by using five kinds of organosilicon compound as gas sources without oxygen by rf plasma-enhanced CVD (PECVD). UV light was irradiated on a substrate vertically during deposition to enhance film oxidation and ablation of carbon contamination in a deposited films. Films prepared with UV irradiation contained less carbon than those prepared without UV irradiation. The oxidation of the films was improved by UN irradiation. The effect of UV irradiation was, however, not observed when the films were prepared with tetramethy lsilane (TMS) which contained no oxygen atom. Dissociated oxygen atoms from an organosilicon compound were excited in the plasma with UV irradiation around the substrate surface and affected the enhancement of film oxidation and ablation of carbon in the films.

• Preventive Nutrition and Food Science
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• v.4 no.2
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• pp.152-158
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• 1999

Polystyrene is frequently used for food packaging because of its eaxy processing rigidity , and low cost. Styrene, which is present in detectable amouts in the polymer, is usually considered to be the substance responsible for the possible tainting of a polystyrene-packed food by migration. The contamination of foods and beverages by trace amounts of materials which have migrated from plastics use din packaging is a concern both on the grounds of adversely affecting product quality and of food safety. These lead to increasing attention to the potentional hazards of a large variety of plastic materials and foods. In this paper we reviewed the history of Styrene and various analytical methods of sample preparation and detection to assess the extent to which styrene is present in food-grade polystrene materials and to what extent it leaked into foods and food stimulants.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.165-166
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• 2006

Nb-Ti alloys were hydrogenated to prepare fine and contamination-free powders. Cracks were introduced in the alloys when they were annealed at 1473 K and cooled in a hydrogen atmosphere. The fragments produced by hydrogen-induced cracking are brittle and the friability enhanced with the Ti content of the alloy, which is beneficial for further refinement of particle size. We also demonstrate that Nb-Ti powders with the average particle size less than 1 m can be produced by ball milling at a temperature lower than 203 K. Furthermore, hydrogen-free powders can then be obtained by annealing above the temperature corresponding to hydrogen desorption from Nb solid solution.

• The Korea Journal of Herbology
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• v.24 no.1
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• pp.9-14
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• 2009

Objectives : The purpose of this study is to investigate on storage characteristics of flavouring oriental medicine materials according to Packaging method(Aluminum package, PP). Methods : This experiments were carried out by field survey and storage characteristics were carried out by physicochemical determination. Results : Flavouring oriental medicine materials were used to in aluminum package to keep original flavour in Japan and Chinese by field and study survey. In view of this survey results, it is very desirable to use zipper Aluminum package in flavouring oriental medicine materials(Perilla perfrutescens var. acuta, Mentha arvensis L. var. piperascens malinvaud). Conclusions : This study results revealed that Aluminum package were superior to any other package method on the basis of keeping original flavour and to reduce microbial contamination in oriental medicine materials.

• Journal of Welding and Joining
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• v.34 no.5
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• pp.19-25
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• 2016

Global warming is hot issue to keep the earth everlastingly. Despite the increase of the world population and the energy demand, the world oil supply and the oil price are hold the steady state. If we are not decrease the world population and the energy consumption, unforeseeable energy crisis will come in the immediate future. AMT acronym of Advanced Materials for Transportation is a non-profitable IEA-affiliated organization to mitigate the oil consumption and the environment contamination for the transportation. In recent, Annex X Multi-materials Joining was added to enhance the car body weight reduction cause the high fuel efficiency and the low emission of exhaust gas. Multi-materials are the advanced materials application technology to optimize the weight, the performance and the cost with the combination of different materials such as Al-alloy, Mg- alloy, AHSS and CFRP. In this study, the trends of AMT strategy and Al-alloy based multi-materials joining technology were review. Also several technologies for Al-alloy dissimilar joining were investigated.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.1
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• pp.36-43
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• 2016

The aim of this study was to evaluate the effect of blood contamination on the push-out bond strength and surface morphology of tricalcium silicate materials; Biodentine$^{(R)}$, Theracal$^{(R)}$ and mineral trioxide aggregate. The standardized lumens of root slices prepared from extracted single-root human teeth were filled with Biodentine$^{(R)}$, Theracal$^{(R)}$ and mineral trioxide aggregate by manufacturer's instruction. The specimens were randomly divided into 2 groups (n = 20) for each material and then incubated for 4 days at $37^{\circ}C$; control group (phosphate buffered saline solution) and experimental group (fetal bovine serum). The push-out bond strengths were then measured by a universal testing machine and the surface morphology of each experimental group was analyzed by scanning electron microscope. Biodentine$^{(R)}$ and Theracal$^{(R)}$ showed higher push-out bond strength compared with mineral trioxide aggregate after exposure to fetal bovine serum. A substantial change in the surface morphology of each material was observed after exposure to fetal bovine serum. In conclusion, the push-out bond strengths of Biodentine$^{(R)}$ and Theracal$^{(R)}$ were higher than mineral trioxide aggregate when exposed to blood contamination. Therefore, it is supposed that the use of Biodentine$^{(R)}$ and Theracal$^{(R)}$ is appropriate in the presence of blood.