• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.4
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• pp.673-682
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• 2001

The use of resin composites has continued to increase over the last several years. In spite of their growing popularity, composites continue to exhibit a number of undesirable characteristics. One of the major deficiencies of composite restorative resins is their inadequate resistance to wear. Of the multitude of factors that have been associated with wear, subsurface degradation within the restoration is considered to be one. The aim of this study was to evaluate the resistance to degradation of four commercial composite resins in an alkaline solution. This solution with a high concentration of hydroxyl ions is a convenient medium for accelerated degradation of silane coupling and filler particles. The brands studies were Definite($Degussa-H\ddot{u}ls$ AG, Germany), Prodigy(Kerr, USA), Pyramid(Bisco, USA) and Synergy(Coltene, Swiss). Preweighed discs of each brand were exposed to 0.1N NaOH solution at $60^{\circ}C$. After 14 days they were removed, neutralized with HCl, washed with water and dried. Resistance to degradation was evaluated on the basis of following parameters : (a) mass loss(%)-determined from pre-and post-exposed specimen weights : (b) Si loss(ppm)-obtained from ICP-AE analysis of solution exposed to specimens; and (c) degradation $depth({\mu}m)$-measured microscopically (SEM) from polished circular sections of exposed specimens. The results were follows: 1. Mass loss of Synergy was $1.24{\pm}0.002%$, it was the highest, there was no significant difference among the materials. 2. The degree of degradation layer depth of Synergy was $107.83{\pm}2.52{\mu}m$, it was the highest, there was no significant difference among any other materials than Synergy. 3. There was no difference among the four materials in Si loss. 4. The correlation coefficient between mass loss and degradation depth was relatively high(r=0.06, p<0.05). 5. There was no coefficient correlation between Si loss and mass loss, the degree of degradation layer depth and Si loss. 6. When observed with SEM, destruction of bonding is observed between resin matrix and filler.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.4
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• pp.685-695
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• 2004

The aim of this study was to evaluate the resistance to degradation and to compare the wear resistance characteristics of four composite resins in an alkaline solution. The resistance to degradation was evaluated on the basis of mass loss(%), degradation depth(${\mu}m$), Si loss(ppm) and wear depth. The brands studied were Heliomolar flow, Filtek supreme, Point4, Tetric flow. The results were as follows: 1. The sequence of the mass loss was in descending order by Heliomolar flow, Filtek supreme, Point4, Tetric flow. There was significant differences among the materials except Heliomolar flow and Filtek supreme. 2. The sequence of the degree of degradation layer depth was in descending order by Filtek supreme, Heliomolar flow, Tetric flow, Point4. There were significant differences among the materials except Heliomolar flow and Tetric flow. 3. The sequence of Si loss was in descending order by Filtek supreme, Heliomolar flow, Point4, Tetric flow. There were significant differences among the materials except Point 4 and Tetric flow. 4. The sequence of maximum wear depth was in descending order by Heliomolar flow, Point4, Fillet supreme, Tetric flow and there was increasing wear depth on soaking in 0.1N NaOH solution. 5. When observed with SEM, destruction of bonding between matrix and filler was observed and when observed with CLSM, the depth of degradation layer of specimen surface was observed. There results indicate that wear and hydrolytic degradation could be considered to be evaluation factors of composite resins.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.2
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• pp.252-260
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• 2009

Whereas the numbers of childcare centers and kindergartens are increasing rapidly, systematic management to control the food safety of foodservice operation is not yet well established. Samples from 12 centers in Seoul and Gyeonggi Province were collected to assess the microbiological quality of 32 raw materials, 24 cooked foods, 76 food-contact surfaces (knives, cutting boards, dish towels and gloves), 17 employees' hands and 12 air-borne bacteria. The microbiological analyses were performed for aerobic plate counts (APC), Enterobacteriaceae, E. coli and 7 pathogens (B. cereus, C. jejuni, C. perfringens, L. monocytogenes, Salmonella spp., S. aureus, and V. parahaemolyticus). Among raw materials, E. coli ($1.39{\sim}2.08\;\log\;CFU/g$) were detected in 4 out of 6 meats and 7.46 log CFU/g of APC in tofu. High enterobacteriaceae levels of 4.23, 5.14 and 4.19 log CFU/g were found in cucumber salad, steamed spinach with seasonings and steamed bean sprout with seasonings, respectively. No pathogens were found in all samples except for C. perfringens detected from raw spinach and raw lotus root. Only APC and enterobacteriaceae were found in food-contact surfaces. Two of the 23 knives and three of the 24 kitchen boards showed over 500 CFU/$100\;cm^2$ of APC; also, APC levels (5.03 to 5.44 log CFU/g) were detected in 4 of the 12 dish towels. Only one glove showed Enterobacteriaceae (2.44 log CFU/glove) contamination. Enterobacteriaceae were found in 2 employees' hands ($2.37{\sim}4.44\;\log\;CFU$/hand) among the 16 employees. The contamination levels of air-borne bacteria were shown unacceptable in two (2.25 and 2.30 log CFU/petri-film/15 min) out of the 12 kitchen areas. These results suggest that the microbiological hazards in some foods and environments are not well controlled and thus a guideline should be provided to ensure the food safety in childcare center and kindergarten foodservice operations.

• Journal of Food Hygiene and Safety
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• v.27 no.2
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• pp.161-168
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• 2012

This study was conducted to evaluate microbial contamination levels of Korea traditional rice cakes such as Sirutteok, Garaetteok and Gyeongdan in the manufacturing process and environment. The microbial contamination levels such as total aerobic bacteria, fungi, coliforms, Escherichia coli, Staphylococcus aureus, Bacillus cereus and Clostridium perfringens of rice cake products were analyzed. The contamination levels of total aerobic bacteria, coliforms, fungi and B. cereus in raw materials were in the range of 2.4~4.5, ND~1.9, 1.2~2.1 and 1.0~2.1 log CFU/g, respectively. The microbial contamination levels of total aerobic bacteria, coliforms, fungi and B. cereus in manufacturing process of rice cakes were increased in the soaking and grinding steps and were decreased in steaming step. E. coli, S. aureus and C. perfringens were not detected in any manufacturing process and environment. The microbial contamination levels of raw materials and final products of rice cake were suitable for microbial safety standard in Korea. However, the manufacturing environment such as equipments and employee's sanitation were in trouble for microbial safety. The results of this study suggest that safety educatio n for personal hygiene and safetymanagement in processing environment are continuously required to assure safety in working environment and employee's individual hygiene.

• Tuberculosis and Respiratory Diseases
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• v.43 no.1
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• pp.46-53
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• 1996

Background: Endotoxin or lipopolysaccharide(LPS) can prime phagocytic cells such as polymorphonuclear leukocytes, monocytes or animal peritoneal macrophages to generate increased amounts of secretory products such as oxygen free radicals and tumor necrosis factor, which play an important role in developing adult respiratory distress syndrome in gram negative sepsis. Human alveolar macrophages(HAM) are continuously exposed to various stimuli inhaled into the alveoli, and the response to LPS might be different in HAM. Therefore, we investigated the effect of LPS pre-exposure on HAM adhered to plastic surface and A549 cell(type II human alveolar epithelial cell line) monolayer. Methods: HAM were isolated from bronchoalveolar lavage fluid from normal lung of the patients with localized lung cancer and esophageal cancer. LPS was exposed to HAM for 2hrs before or after adherence to plastic surface of 24-well Linbro plate and A549 cell monolayer. And then HAM was stimulated with PMA(phorbol myristate acetate) or fMLP(N-formyl-methionylleucyl-phenylalanine). The amount of hydrogen peroxide($H_2O_2$) production in the supernatant was measured on the principle of peroxidase-dependent oxidation of phenol red by hydrogen peroxide. Results: LPS pre-exposure could not enhance $H_2O_2$ production in neither HAM adhered to plastic surface nor one to A549 cell monolayer. But LPS even in the absence of PMA or fMLP stimulation directly increased $H_2O_2$ release in HAM if added after the adherence to A549 cell monolayer. Conclusion: Endotoxin does not prime HAM, but may directly activate HAM adhered to alveolar epithelial cells. Further investagation will be necessary.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.4
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• pp.723-729
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• 2004

To develop foods using dried persimmon, hot-water extracts of dried persimmons were added into strong wheat flour in the ratio of 10, 20, 30, and 40% and the quality characteristics of baked products were investigated. The proximate compositions of dried persimmons hot-water extracts were 70.37% of moisture, 1.72% of crude protein, 0.18% of crude lipids, 1.99% of crude ash and 4.37% of crude fiber, respectively. With increasing the addition of dried persimmons hot-water extracts, moisture content of the added breads was increased to 47.20% from 41.12% of non-added bread and water activity to 0.576 from 0.495. Water binding capacity of the added dried persimmons hot-water extracts rasied weight of the bread but decreased specific volume. In the hunter's color values the more dried persimmons hot-water extracts was added, the lower L vaules we, and the higher a and b values we. In the texture property, the addition of dried persimmons hot-water extracts increased hardness, gumminess and chewiness, while decreased adhesiveness and fracturability. Judging from texture, taste and overall acceptability of the product, recommended substitution level for hot-water extracts of dried persimmons in bread was 30% or less.

• Journal of Food Hygiene and Safety
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• v.27 no.3
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• pp.264-270
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• 2012

This study was performed to compared the effectiveness of individual treatments (electrolyzed water: EW, organic acid, and ultrasound) and their combination on reducing foodborne pathogens from perilla leaves. Perilla leaves were innoculated with a cocktail of Salmonella Typhimurium, Staphylococcus aureus, Bacillus cereus. Inoculated perilla leaves were treated with EW combined with different concentration of acetic acid (0.5%, 1.0%, 1.5%, 2.0%) for 1 min at room temperature. Treatment of 3 pathogens on perilla leaves with electrolyzed water combined with ultrasound (25 kHz) and 0.5% acetic acid was also performed for 1 min. While the numbers of S. Typhimurium and B. cereus showed reduced with increasing acetic acid concentration, there is no difference in the number of S. aureus treated with EW containing 0.5% to 1.5% acetic acid. Discoloration was observed the perilla leaves treated with EW combined with more than 1.0% acetic acid. For all three pathogens, the combined treatment of EW and ultrasound resulted in additional 0.42 to 0.72 $log_{10}$ CFU/g. The maxium reductions of S. Typhimurium and B. cereus were 0.95, 1.23 $log_{10}$ CFU/g after treatment with EW combined with 0.5% acetic acid and ultrasound simultaneously. The results suggest that the treatment of EW combined with 0.5% acetic acid and ultrasound increased pathogens reduction compared to individual treatment.

• Food Science of Animal Resources
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• v.24 no.4
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• pp.335-341
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• 2004

This study was carried out to evaluate the microbiological quality of poultry carcasses at different slaughtering process in large (>50,000 chicken/day) and small (<30,000 chicken/day) scale slaughtering houses. Whole bird rinse technique was used to analyze the incidence of microorganisms on poultry carcasses in each process of before visceration, after evisceration, after final wash, after main chilling and in cold room. In summer time, small scale slaughterhouse showed lower incidence of aerobic microorganisms (10$\^$4/ CFU/mL) than those of large scale slaughterhouse (10$\^$5/ CFU/mL) at the process of after main chilling and in cold room. But small scale slaughterhouse showed higher incidence of E. coli (10$^2$-10$^4$ CFU/mL) than those of large scale slaughterhouse (10$\^$-2/ CFU/mL) at each slaughtering process observed. During autumn and winter time, small scale slaughterhouse showed similar incidence of aerobic microorganisms as large scale slaughterhouse (10$\^$5/ CFU/mL after evisceration, 10$^4$ CFU/mL after main chilling and cold storage). Samples from carcasses during autumn and winter time in cold room showed no difference in E. coli counts (10$^2$ in autumn time and 10$^3$ CFU/mL in winter time) between large and small scale slaughterhouse. In spring time, small scale slaughterhouse showed lower incidence of aerobic microorganisms than those of large scale slaughterhouse at each slaughtering process observed except after main chilling. Small scale slaughterhouse showed higher incidence of aerobic microorganisms in final cooling water than large scale slaughterhouse during spring time.

• Journal of Conservation Science
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• v.30 no.3
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• pp.263-275
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• 2014

It's shown how to proceed the study on Manufacturing techniques & Conservation to the Iron Pot from Cheonmachong Ancient Tomb(the 155th Tomb in Hwangnam-dong). In order to investigate manufacturing techniques of the Iron Pot, some parts of the relic were gathered. After mounting, polishing and etching on the relic, analyzing the metal microstructure was conducted. Also it's conducted a SEM-EDS analysis on the nonmetallic inclusion. White iron structure was observed in the metallurgical structure inspection, SEM-EDS analysis. It seems to be dried slowly at room temperature after casting, doesn't look as particular heat treatment to improve brittleness. It is estimated that it's as the handle seam side were verified about 3cm inch wide, 1.5 thick in center of body, so 2 separate half-completed products was cast with width-type mould. The manufacturing techniques Using white cast iron structure, width-type mould are observable to the Iron Pot excavated from Sikrichong Ancient Tomb & Hwangnamdaechong grand Ancient Tomb around those were constructed the same time. It's able to recognize that it's almost identical manufacturing techniques at that time. Conservation is generically following those are survey of pretreatment, foreign material removal, stabilization, restoration and color matching in the order. cleaning & drying were added to the process as occasion demands. The strengthening treatment were difficult with artifact's volume, low concentration Paraloid NAD-10 solution was spread two or three times with a brush, surface hardening also came up with 15wt% Paraloid NAD-10 solution after the conservation was complete. There were connection & restoration for the restoration to the damage after modeling forms that it's similar to damaged parts by using the Fiber Reinforced Plastic resins(POLYCOAT FH-245, mold laminated type). Throughout this research, capitalizing on accumulations of measurements about the production technique of Iron Pot in the time of the fifth and 6th centuries is no less important than the Iron artifact's conservation for a better study in the future.

• Tuberculosis and Respiratory Diseases
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• v.45 no.1
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• pp.36-44
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• 1998

Background: IFN-$\gamma$ is known to activate mononuclear phagocytes and to mediate host defense mechanism against some intracellular microorganisms, but little is known about anti-mycobacterial activity and mechanism of IFN-$\gamma$ in human. In this study, we investigated the role of IFN-$\gamma$ in the pathogenesis of tuberculosis by observing the effect of IFN-$\gamma$ on the phagocytosis of M.tuberculosis(MTB) and on the production of TNF-$\alpha$ by human pulmonary alveolar macrophage. Method: Pulmonary alveolar macrophage(PAM) were prepared with adhesion purification method from bronchoalveolar lavage fluid obtained from 8 persorn without active lung lesion and cultured($1{\times}10^6cells/ml$) with MTB($3{\times}10^7$ bacteria/ml) with or without IFN-$\gamma$(300U/ml), LPS(0.5ug/ml) and autologous serum(10%). After 2 hours, the percentage of PAM-phagocytosed MTB was counted after AFB staining(modified Kynion method). TNF-$\alpha$ production by PAM stimulated by IFN-$\gamma$(300U/ml), MTB($1{\times}10^6bacteria/ml$) and LPS(0.5ug/ml) for 24hours was measured in culture supernatant using ELISA method. The degree of phagocytosis of MTB by PAM stimulated with IFN-$\gamma$(300U/ml) and LPS(0.5ug/ml) for 24hours was also investigated. Results: IFN-$\gamma$ did not influence the phagocytosis of MTB by PAM(percentage of PAM-phagocytosed MTB: control: $22.1{\pm}4.9$, IFN-$\gamma$: $20.3{\pm}5.3$) and did not increase TNF-$\alpha$ production by PAM (control: $21{\pm}38pg/ml$, IFN-$\gamma$: $87{\pm}106pg/ml$), and the degree of phagocytosis of MTB by PAM pre-stimulated with IFN-$\gamma$ for 24 hours, was not increased (control: $24.5{\pm}9.5$, IFN-$\gamma$: $23.4{\pm}10.1$). Conclusion: IFN-$\gamma$ does not influence on the phagocytosis of MTB and TNF-$\alpha$ production by PAM.