• Advances in materials Research
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• v.4 no.4
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• pp.193-205
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• 2015

Contamination by bacterial strands is a major problem after bone replacement surgeries, so there is a great need to develop low cost biocompatible antibacterial bioactive scaffolds to be used in bone tissue engineering. For this purpose, nano-zinc doped hydroxyapatite with different zinc-concentrations (5, 10 and 15 mol%) was successfully prepared by the wet chemical precipitation method. The prepared powders were used to form porous scaffolds containing biodegradable Ca-cross-linked alginate (5%) in order to enhance the properties of alginate scaffolds. The scaffolds were prepared using the freeze-gelation method. The prepared powders were tested by X-ray diffraction; transmission electron microscope and Fourier transform infrared analyses, while the prepared scaffolds were investigated by Fourier transform infrared analyses, thermogravimetric analyses and measurement of the antibacterial properties. Best results were obtained from scaffold containing 15% mol zinc-doped hydroxyapatite powders and 5% alginate concentration with ratio of 70:30.

• Korean Journal of Materials Research
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• v.17 no.5
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• pp.263-267
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• 2007

Hafnium oxide $(HfO_2)$ films were deposited on Si(100) substrates by remote plasma-enhanced atomic layer deposition (PEALD) method at $250^{\circ}C$ using TEMAH [tetrakis(ethylmethylamino)hafnium] and $O_2$ plasma. $(HfO_2)$ films showed a relatively low carbon contamination of about 3 at %. As-deposited and annealed $(HfO_2)$ films showed amorphous and randomly oriented polycrystalline structure. respectively. The interfacial layer of $(HfO_2)$ films deposited using remote PEALD was Hf silicate and its thickness increased with increasing annealing temperature. The hysteresis of $(HfO_2)$ films became lower and the flat band voltages shifted towards the positive direction after annealing. Post-annealing process significantly changed the physical, chemical, and electrical properties of $(HfO_2)$ films. $(HfO_2)$ films deposited by remote PEALD using TEMAH and $O_2$ plasma showed generally improved film qualities compare to those of the films deposited by conventional ALD.

• Progress in Superconductivity and Cryogenics
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• v.11 no.4
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• pp.20-24
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• 2009

YBCO coated conductors (CC) on the $CeO_2$-buffered IBAD-MgO template were fabricated by metal-organic deposition (MOD) Process with Ba-trifluoroacetate and fluorine-free Y and Cu precursor materials. The precursor solution was coated on $CeO_2$-buffered IBAD MgO templates using the multiple dip-coating method, decomposed into inorganic precursors by pyrolysis up to $400^{\circ}C$ within 3 h, and finally fired at $740{\sim}800^{\circ}C$ in a reduced oxygen atmosphere. Microstructure, texture, and superconducting properties of YBCO films were found highly sensitive to both the firing temperature and time. The high critical current density ($J_C$) of $1.15\;MA/cm^2$ at 77.3K in the self-field could be obtained from $1\;{\mu}m$ thick YBCO CC, fired at $740^{\circ}C$ for 3.5 h, implying that high performance YBCO CC is producible on IBAD MgO template. Further enhancement of $J_C$ values is expected by improving the in-plane texture of $CeO_2$-buffer layer and avoiding the metal substrate contamination.

• Journal of the East Asian Society of Dietary Life
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• v.19 no.2
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• pp.256-264
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• 2009

This study investigated the status of foodservice operations and perceived performance of management for school dietitians in the Kyunggi area. According to the results, the perceived performance of dietitians for cooking management presented an overall average of $3.90{\pm}0.61$, and carrying out examination and preservation of food was the highest among all sectors with $4.83{\pm}0.49$. The area of cross contamination marked a total average of $4.15{\pm}0.67$, and the perceived performance of serving management was lower than the sanitary management of cooking and cross contamination with $3.64{\pm}0.75$. The most recognized cause on foodborne illness was food materials (44.6%). Sanitary level, the temperature of most foods, and the personal hygiene of workers were also important causes of foodborne illness.

• Korean Journal of Poultry Science
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• v.20 no.1
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• pp.33-41
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• 1993

Among the several factors that affect shelf-life of washed shell eggs, storage temperature and relative humidity were the most important. Besides those factors listed above, temperature of washing water, composition of foreign substances and washing method of eggs were also the factors affecting the shelf-life of the eggs. The effect of sanitizer treatment was significant in extending the shelf-life of eggs compared with washed and unwashed eggs. In case of oil coating treatment, the shell eggs treated showed the better results than that of washed and unwashed eggs because the coating materials prevented the moisture evaporation from the inner shell eggs and kept the contamination of microorganisms from the environment. Consequently, it is considered that reducing egg shell contamination of microorganisms and proper treatment could be the key to extend the shelf-life of shell eggs.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.576-580
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• 2001

The amount of the waste foundry sand(WFS) produced in Korea is over 700,000 ton per year, but most WFS buries itself and only 5~6% or total WFS is recycled in the way or mixing as fine aggregate for construction materials. A bY-product, WFS produced from a foundry may affect our environmental contamination if it is discharged without proper waste disposal in Korea. Therefore in this study, we performed the fundamental research about specific gravity, absorption, grading curve, finesse modulus of WFS, different aggregates and the flow and the compressive strength of mortar with WFS replaced as fine aggregate, the workability and compressive strength of concrete with WFS as fine aggregate aimed at the specified strength of 270 kgf/$\textrm{cm}^2$, and then optimum mix proportion of concrete was determined

• Journal of Radiation Protection and Research
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• v.9 no.2
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• pp.112-117
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• 1984

A lot of radioisotopes are applied to medical fields. It's very important to measure the activities on airborne radioiodine discharged in air from $Na^{131}I$ solutions and from patients treated with radioiodine. Also surface decontamination is another one important problem to be completly solved in the isotope laboratory where there is always the possibility of radiation contamination. The Authors measured the activities on airborne radioiodine with RI collector and scintillation counter. 1. The mean accumulative activity of airborne radioiodine discharged into air from $Na^{131}I$ solution was measured as $1.3{\times}10^{-3}/hr$ rate, and the maximum value was $1.8{\times}10^{-3}/hr$. 2. Radioactivity rate per hour of airborne iodine discharged into air from patients treated with $Na^{131}I$ was measured as $6.2{\times}10^{-5}/hr$ at 8 hour after administration of radioiodine and decreased into $2{\times}10^{-6}/hr$ after 24 hour. 3. Metalic surfaces such as stainless steel or aluminum are decontaminated 5 to 6 times more rapidly than wood and concrete surfaces. 4. Decontamination with wet wiping with detergent was 9 to 10 times more rapidly than dry wiping method, but dry wiping was useful for the first step to prevent spreading and flowing from liquid radioactive materials.

• Journal of Nutrition and Health
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• v.37 no.8
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• pp.722-731
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• 2004

The objective of this study was to evaluate the microbiological quality of non-heat-processed foods for implementation of a HACCP (Hazard Analysis and Critical Control Point) system in day-care center foodservice operations. The evaluating points were microbial assessment of foods, utensils, and employee's hands during preparation, cooking, and serving. The temperature of non-heated food being served was also measured. Microbiological quality was assessed using 3 M Petrifilm/syp TM/ to measure total plate count and coliforms for food and utensils and Staphylococcus aureus for hands in five Gumi day-care centers. Results showed low microbiological quality of non-heated foods. This was probably due to contaminated raw ingredients and cross-contamination that occurred during preparation and cooking (e.g., unsatisfactory washing and disinfection of raw materials and utensils). These results suggest that it is essential to educate employees on good personal hygiene (hand washing) , prevention of cross-contamination through use of properly washed and sanitized utensils, and proper washing and disinfection of raw vegetables. Establishing Sanitation Standard Operating Procedures (SSOPs) are an essential part of any RACCP system in day-care center foodservice operations.

• Mycobiology
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• v.47 no.4
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• pp.430-440
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• 2019

Fungal contamination of built-in furniture is a frequent problem in Korea when new apartment is built. However, domestic information on the contaminating fungi is very limited. This study was conducted to isolate, identify and characterize the fungi of the problem in one of the apartment houses where the fungi were claimed in the built-in furniture before the house owner moves in. Fungi present in the furniture installed in a main room, dress room, and kitchen side were visually and microscopically confirmed and purely isolated on PDA. The isolated fungi were identified by analyzing the morphological characteristics and nucleotide sequence of the ITS, calmodulin gene, and TEF-1α gene. Aspergillus creber, A. niger, A. pseudoglacus, A. ruber, Cladosporium perangustum and Penicillium commune were identified. Four out of the six fungal species were positive for at least one enzyme in six kinds of extracellular enzyme assays. When these four species (A. creber, A. niger, C. perangustum and P. commune) were inoculated onto four kinds of wood chips of furniture materials, they were able to colonize all of the wood chips. Their settlement was better at 95% humidity condition than at 30% humidity condition. Among the four species, C. perangustum caused the darkest discoloration and secreted the most number of extracellular enzymes. The four species were re-isolated from the colonized wood chips and confirmed as the problematic fungi in the built-in furniture.

• Food Science and Biotechnology
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• v.16 no.4
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• pp.621-625
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• 2007

Staphylococcus aureus in Korean kimbab rolls was monitored seasonally in 4 major cities of Korea to investigate the risk of S. aureus in a pre-prepared meal. Thirty-five (28.6%) of 105 kimbab rolls purchased in winter were contaminated with S. aureus with an average level of 2.6 log CFU/g. Thirty-six (33.0%) of 109 kimbab rolls purchased in summer and autumn were contained S. aureus with an average level of 2.9 log CFU/g. Kimbab purchased in snack bars showed higher S. aureus contamination rates with the maximum level of 4.7 log CFU/g than that purchased in convenience stores. Of the raw materials in kimbab, uncooked perilla leaf had the highest contamination rate of S. aureus. Less than 50% of S. aureus isolated from kimbab produced enterotoxin and most of the staphylococcal enterotoxin produced by S. aureus in kimbab was type A.