• Title, Summary, Keyword: contamination materials

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Research and development of advanced COS for anti-contamination (염진해 특성이 향상된 COS의 개발에 관한 연구)

  • Kim, L.S.;Han, D.H.;Ahn, M.S.;Cho, H.G.;Kang, D.P.;Hwang, D.S.
    • Proceedings of the KIEE Conference
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    • pp.1599-1602
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    • 1994
  • Recently, failure of COS(cut out switch) due to contamination has been increased. This paper is on the development of the contamination COS. 1 We designed a porcelain insulator of alternate shed for anti-contamination COS. 2 The COS was coated with HVIC(silicone) to improve resistivity to contamination. 3 The FOV characteristics of COS were examined to obtain dry FOV, wet FOV and contamination FOV.

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Effect of Contamination of Liquid Crystal by Spilled Components from Color Filter

  • Kim, Young-Seok;Lee, Jeong-No
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.1469-1471
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    • 2009
  • Effect of contamination of liquid crystal on the electrical behavior of liquid crystal display (LCD) by spilled components from color filter layer was investigated. It is noted that the level of contamination was different following the kind of liquid crystal and organic layers. Transmittance curve of LCD cell was shifted by spilled components of color filter and BM materials. C-V curve also showed different behavior following color filter type. The results obtained show the image sticking of LCD can be varied by pairing liquid crystal with color filter materials.

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Assessment of Contamination of Harbor Dredged Materials for Beneficial Use (항만준설토사 유효활용을 위한 오염도 평가)

  • Yoon, Gil-Lim;Jeong, Woo-Seob
    • Journal of the Korean Geotechnical Society
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    • v.24 no.5
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    • pp.15-25
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    • 2008
  • Contamination level assessment of harbor dredged materials is carried out for beneficial use, which generated annually due to port construction and maintenance of harbor channel. The basic purpose of environmental risk assessment was a scientific approach to susceptibility of hazard risk to human's health from different dredged materials. And this paper proposes a guideline of safely beneficial use of dredged materials at both industrial area and residental area, generated from major port execution throughout a sound investigation of their contamination levels. Newly proposed guidelines were in general higher levels compared to both current guidelines of treatment and use of dredged materials and soil environment protection levels. Finally, environmental assessment results of dredged material contamination generated in major ports of Korea for beneficial use based on pre-assessment environmental levels show that some port's dredged materials contain heavy metals such as Cd, As, Cr and Zn, more than base levels which requires more precise contamination investigation. Others were found to be very appropriate for beneficial use.

Analysis of Contamination of Bacteria from Raw Materials, Utensils and Workers' Hands to Prepared Foods in Foodservice Operations (원재료, 조리기구와 조리원 손에 의한 급식소 조리음식의 미생물오염 실태 분석)

  • Bae, Hyun-Joo
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.35 no.5
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    • pp.655-660
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    • 2006
  • The purpose of this study was to analyze the microbiological hazards of prepared foods, raw materials, utensils and workers' hands and to evaluate cross-contamination of bacteria in foodservice establishments. Aerobic plate counts, coliforms, E. coli, E. coli O157:H7, Salmonella spp., Staphylococcus aureus and Listeria monocytogenes were tested. According to the microbiological evaluation, there were many cases of contamination of bacteria. Staphylococcus aureus was detected in chicken stew (Korean type), Japchae, Bibimbap and Kongnamul-muchim at the A foodservice establishment and Jwieochae-jorim at the B foodservice establishment. E. coli was detected in Ojingeochae-muchim at the C foodservice establishment. E. coli O157:H7, Salmonella spp. and Listeria monocytogenes were not detected in any of the tested samples. Critically, microbiological contamination of raw materials, utensils and workers' hands could result in contamination of prepared foods, thus, attention needs to be given to sanitation of raw materials, workers' hands and utensils to reduce or eliminate contamination of bacteria.

On the Microbial Contamination in Softdrink Manufacturing Process (청량음료의 미생물 오염에 대하여)

  • 김용배;이병국;유건희;조남선
    • Korean Journal of Microbiology
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    • v.11 no.3
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    • pp.129-133
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    • 1973
  • 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.

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Evaluation of Risk rates for Foreign Materials in a Minienvironment (클린룸 국소환경에서 이물의 위험율 평가)

  • Noh, Kwang-Chul;Oh, Myung-Do
    • Proceedings of the SAREK Conference
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    • pp.600-605
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    • 2007
  • In this study, the risk rates of different contamination sources of the Foreign material in a minienvironment were analyzed through CFD simulation. From the results, the ambient contamination sources mainly affect wafers in the FOUP, whereas the internal contamination sources mainly affect wafers laid on the robot arm in the minienvironment. And the purging plenum system is very useful in protecting the wafers in the FOUP from Foreign materials transferred from the FFU. However, this system is unable to protect the wafers on the robot arm from internal Foreign materials and the wafers in the FOUP from sources of the interface between the FOUP and the minienvironment.

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ADHESIVE PROPERTY OF POLYSULFIDE IMPRESS10N MATERIAL ON THE TRAY RESIN AND BORDER HOLDING MATERIALS (타액오염이 트레이 레진 및 변연 형성재와 Polysulfide 인상재의 접착력에 미치는 영향)

  • Kim, Yong-Hak;Yang, Hong-Seo
    • 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.

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Contamination Particle and Cracking Behavior of the Anodic Oxidation in Sulfuric Acid Containing Cerium Salt (세륨염을 첨가한 황산법 양극산화피막의 오염입자 및 열크랙 거동)

  • So, Jongho;Yun, Ju-Young;Shin, Jae-Soo
    • Journal of the Semiconductor & Display Technology
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    • v.17 no.4
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    • pp.11-15
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    • 2018
  • The parts of equipment for semiconductor are protected by anodic aluminum oxide film to prevent corrosion. This study investigated contamination particle and cracking behavior of anodic oxidation in sulfuric acid containing cerium salt. The insulating properties of the sample were evaluated by measuring the breakdown voltage. It was confirmed that the breakdown voltage was about 50% higher when the cerium salt was added, and that the breakdown voltage after the heat treatment was 55% and 35% higher at $300^{\circ}C$ and $400^{\circ}C$, respectively. After heating at $300^{\circ}C$ and $400^{\circ}C$, cracks were observed in non cerium and cerium 3mM, and more cracks occur at $400^{\circ}C$ than at $30^{\circ}C$. The amount of contamination particles generated in the plasma is about 45% less than that of non-cerium specimens.

The Effect on the Microroughness of Si Substrate by Metallic Impurity Ca (금속 불순물 Ca이 Si 기판의 표면 미세 거칠기에 미치는 영향)

  • Choe, Hyeong-Seok;Jeon, Hyeong-Tak
    • Korean Journal of Materials Research
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    • v.9 no.5
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    • pp.491-495
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    • 1999
  • In this study, we focus on Ca contaminant which affects on the roughness Si substrate after thermal process. The initial Si substrates were contaminated intentionally by using a standard Ca solution. The contamination levels of Ca impurity were measured by TXRF and the chemical composition of that was analyzed by AES. Then we gre the thermal oxide to investigate the effect of Ca contaminants. The microroughness of the Si surface, the thermal oxide surface, and the surface after removing the thermal oxide were measured to examine the electrical characteristics. The initial substrates that were contaminated with the standard solution of Ca exhibited the contamination levels of 10\ulcorner~10\ulcorneratoms/$\textrm{cm}^2$ which was measured by TXRF. The Ca contaminants were detected by AES and exhibited the peaks of Ca, SI, C and O.After intentional contamination, the surface microroughness of this initial substrate was increased from $1.5\AA$ to 4$\AA$ as contamination levels became higher. The microroughness of the thermal oxide surfaces of both contaminated and bare Si substrates exhibits similar values. But the microroughness of the contaminated$ Si/SiO_2$ interface was increased as contamination increased. The thermal oxide of contaminated substrate exhibited the small minority carrier diffusion length, low breakdown voltage, and slightly high leakage current.

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