• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1528-1530
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• 1997

As device size shrinks, contamination will increasingly affect the reliability and yield of device. Therefore, contaminants must be removed from the surfaces of Si wafers prior to each process. But it becomes out increasingly difficult to clean silicon surfaces with finer patterns by the conventional wet treatment because of the viscosity and surface tension of solutions. Hence, a damage less dry cleaning process is needed for the silicon surfaces. For the removal of Si native oxide by UV-enhanced dry cleaning. $F_2$ gas and $F_2/H_2$ mixed gas were applied. As a result of analysis, UV-enhnaced $F_2/H_2$ treatment is more suitable than UV-enhanced $F_2$ treatment for removal of native oxide on the surfaces of Si wafers.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.11
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• pp.1770-1776
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• 2007

Beef carcasses were examined to explore the effects of spinal cord removal and washing on central nervous system tissue (CNST) decontamination of the surface during the slaughtering process. A total of 15 carcasses were split by sawing centrally down the vertebral column and left sides of split carcasses were used for analysis. Samples were collected by swabbing the surface from 4 defined parts on the interior and 4 on the exterior of carcasses from the abattoir and analyzed using an ELISA-based test. The results showed that automatic and manual spray washing decreased CNST contamination, especially on the interior ventral parts of carcass surfaces (p<0.01), but did not decrease CNST on the interior dorsal parts. Increasing washing time to 60 s did not affect the reduction of CNST contamination. Samples following spinal cord removal prior to splitting showed lower calculated levels of "risk material" than the stated limit of detection (0.1%) of the ELISA kit on interior and exterior carcass parts (p<0.01). Therefore, spinal cord removal prior to splitting could be a very effective way to minimize CNST contamination of beef carcasses.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.11
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• pp.86-91
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• 2021

Recently, functional clothes that can reduce deposition and/or penetration of fine dust have been developed. However, there are no methods to quantitatively evaluate the performance of these clothes. In this study, we developed a method to contaminate a fabric using fine dust and established an approach to quantitatively assess the degree of particle contamination on the fabric surface. Silicate powder was chosen as the particle to simulate fine dust because silicate particles are fluorescent under UV light; therefore, they can be distinguished from any color of non-fluorescent fabric surface. A camera with a high-resolution lens system was used to scan the surface of the contaminated fabric surface, and the degree of particle contamination of the fabric surface was analyzed in terms of the pixels corresponding to the area of the fabric surface contaminated by silicate particles. Finished or unfinished nylon fabrics as well as cotton fabrics were contaminated with silicate particles, and their surfaces were scanned using the established camera. The proposed assessment method was found to be useful for quantitatively comparing the degree of particle contamination of the fabrics.

• Journal of Korea Foundry Society
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• v.24 no.1
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• pp.3-9
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• 2004

Die casting is "a process in which molten metal is injected at high velocity and pressure into a mold(die) cavity". Casting with smooth surfaces, high dimensional precision, complicated shapes, and reduced weight can be obtained using this process. But this process is susceptible to casting defects such as porosities, scattered chilled layers, hard spots, etc. For preventing casting defects, we developed "low-velocity high pressure die casting technology", "squeeze die casting technology", "heat insulating sleeve lubricant technology", and "direct pouring technology". The "direct pouring technology" is useful for producing molten metal without oxide contamination. It consists of a pumping system which supplies pure molten metal to the die casting machine. By using this technology, we have successfully reduced oxide contamination in castings to 1/20 of that of our previous castings.

• Journal of Food Hygiene and Safety
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• v.12 no.1
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• pp.78-82
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• 1997

Surface swab samples from beef (188), pork (240) and chicken (95) carcasses were collected from slaughterhouse in Kangwon and Kyunggi areas from March through July 1996. The samples were examined on the level of E. coli biotype I relevant to fecal contamination due to unsanitary processing control and the existence of verocytotoxin-producing E. coli (VTEC). E. coli biotype I were confirmed from 38.8% of beef, 40.0% of pork, and 69.5% of chicken carcasses. Little variation was noted among three sampling points; rump, flank and neck of beef, ham, belly and jowls of pork. coli O157:H7 was only confirmed from 2 of 188 beef carcasses. E. coli biotype I. All the isolated E. coli O157 showed positive for vero cell cytotoxicity test. Isolation rate of E. coli O157 in summer was higher than in spring. In case of pork and chicken carcasses, E. coli O157 was isolated in summer only.

• Journal of Food Hygiene and Safety
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• v.29 no.4
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• pp.253-259
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• 2014

This study was conducted to investigate survival of Bacillus cereus (B. cereus) on stainless steel and polyvinyl chloride (PVC) and its transfer from two material to lettuce. The stainless steel and PVC were innoculated with B. cereus and stored at 6 combination conditions (temperature : $20^{\circ}C$ and $30^{\circ}C$, relative humidity (RH) : 43%, 69%, and 100%). Although the total numbers of B. cereus at RH 43% and RH 69% were reduced by 3.53-4.00 log CFU/coupon within 24 h regardless of material type, the spore numbers of B. cereus was lasted at 3.0 log CFU/coupon. When two materials were stored at $30^{\circ}C$, RH 100%, the spore numbers of B. cereus was rapidly increased by 3.0 log CFU/coupon. In addition, the reduction rate of B. cereus was decreased in the presence of organic matter. Transfer rate of B. cereus from surface of stainless steel and PVC to lettuce was increased by 10 times in the presence of water on the lettuce surface. As a result of this study, the presence of B. cereus on produce contact surfaces can increase the risk of cross-contamination. Thus, it is important that the packing table and conveyer belt in post harvest facility should be properly washed and sanitized after working to prevent cross-contamination.

• Journal of Microbiology
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• v.40 no.4
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• pp.327-330
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• 2002

The purpose of this research was to test multiplex polymerase chain reaction in investigating the microbiological quality of the risky surfaces in social living places of a military base where over 15 thousand people live together. In 22 samples of 99, there were no bacteria. Only four of the samples contained Shigella, and one of them contained Salmonella, but 77 of the samples contained thermotolerant coliform organisms. There was no statistically significant difference among the microbiological quality of different sites and different equipment surfaces (p>0.05).

• Proceedings of the Korean Society of Food Hygiene and Safety Conference
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• 1999.10a
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• pp.29-70
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• 1999

Current food sanitation systems for meat and livestock in Australia ar underpinned by HACCP-based quality assurance. HACCP-based quality assurance programs have been implemented by all australian red meat industry sectors, from 'farm-to-fork'. These quality assurance programs are (along with other quality and food safety considerations) the collection of a series of sanitation steps and strategies that aim to ensure that only healthy, clean livestock are presented for slaughter; those healthy, clean animals enter a clean processing plant; contact of carcase surfaces with potential sources of contamination is avoided; carcase surfaces are decontaminated before chilling; and subsequent growth of potential contaminants is avoided. Prospects for food sanitation systems for meat and livestock in Australia lie largely in enhancing current and applying new sanitation strategies and procedures within our HACCP-based quality assurance framework. Prospects include increased focus on actual (Versus perceived) risks; on-farm/feedlot pathogen elimination; increased implementation of existing (or new) decontamination technologies; and an improved cold chain.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3279-3281
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• 1999

This paper describes a method of direct wafer bonding using surfaces activated by a radio-frequency hydrogen plasma. The hydrogen plasma cleaning of silicon in the RIE mode was investigated as a pretreatment for silicon direct bonding. The cleaned silicon surface was successfully terminated by hydrogen, The hydrogen-terminated surfaces were rendered hydrophilic, which could be wetted by Dl water rinse. Two wafers of silicon and silicon dioxide were contacted to each other at room temperature and postannealed at $300{\sim}1100^{\circ}C$ in an $N_2$ atmosphere for 2 h. From the AFM results, it was revealed that the surface became rougher with the increased plasma exposure time and power. The effect of the plasma treatment on the surface chemistry was investigated by the AES analysis. It was shown that the carbon contamination at the surface could be reduced below 5 at %. The interfacial energy measured by the crack propagation method was 122 $mJ/m^2$ and 384 $mJ/m^2$ for RCA cleaning and hydrogen plasm, respectively.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.1
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• pp.39-47
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• 2009

The METRO-K is a model for a radiological dose assessment due to a radioactive contamination in the Korean urban environment. The model has been taken part in the Urban Remediation Working Group within the IAEA's (International Atomic Energy Agency) EMRAS (${\mathbf{\underline{E}}}nvironmental$ ${\mathbf{\underline{M}}}odeling$ for ${\mathbf{\underline{RA}}}diation$ ${\mathbf{\underline{S}}}afety$) program. The Working Croup designed for the intercomparison of radioactive contamination to be resulted from the explosion of a radiological dispersal device in a hypothetical city. This paper dealt intensively with a part among a lot of predictive results which had been performed in the EMRAS program. The predictive results of three different models (METRO-K, RESRAD-RDD, CPHR) were submitted to the Working Group. The gap of predictive results was due to the difference of mathemathical modeling approaches, parameter values, understanding of assessors. Even if final results (for example, dose rates from contamintaed surfaces which might affect to a receptor) are similar, the understanding on the contribution of contaminated surfaces showed a great difference. Judging from the authors, it is due to the lack of understanding and information on radioactive terrors as well as the social and cultural gaps which assessors have been experienced. Therefore, it can be known that the experience of assessors and their subjective judgements might be important factors to get reliable results. If the acquisition of a little additional information is possible, it was identified that the METRO-K might be a useful tool for decision support against contamination resulting from radioactive terrors by improving the existing model.