• Restorative Dentistry and Endodontics
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• v.27 no.1
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• pp.16-23
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• 2002

Physical properties of composite resins such as strength, resistance to wear, discoloration, etc depend on the degree of conversion of the resin components. The purpose of this study was to evaluate the degree of conversion of the composite resins according to the thickness of tooth structure penetrated by light and applied light curing time. The coronal portions of extracted human teeth (one anterior tooth, three posterior tooth) was embedded by pink denture material. the mounted teeth were cut into three illumination sections (1mm thickness enamel section, 1mm thickness dentin section, 2mm thicknes dentin section) and one backing section with cutting wheel. Thin resin films were made by using 6kg pressure between slide glass during 5 minutes Thin resin film was light cured on coupled illumination section during 40sec, 80sec and 120sec. each illumination section was coupled as follows; no tooth structure(X), ename section(E), enamel section + 1mm dentin section(ED1), enamel section + 2mm dentin section(ED2), enamel section + 1mm dentin section + 2mm dentin section(EDD). To simulate the clinical situation more closely, thin resin films was cured against a backing section of tooth structure. The degree of conversion of carbon double bonds to single bonds in the resin films were examined by means of Fourier Transform Infrared Spectrometer. The results were obtained as follows ; 1 As curing time was increased, conversion rate was increased and as tooth thickness which was penetrated by curing light was increased, conversion rate was decreased. 2. At all tooth thickness groups, conversion rate between 80sec and 120sec was not significantly increased(P＞0.05). 3. At 40sec group and 80sec, conversion rate between no tooth structure(X) group and 1mm enamel section(E) group was not significantly decreased(P＞0.05). 4. At 80sec group and 120sec, conversion rate between 1mm enamel section(E) group and 1mm enamel section + 1mm dentin section(ED1) group was not significantly decreased(P＞0.05).

• Journal of the Korean Society for Railway
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• v.17 no.2
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• pp.94-99
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• 2014

Recently, trends in new transportation system development have been primarily focused on sustainable and ecofriendly mobility solutions. The personal rapid transit (PRT) system has been considered a promising candidate in this category; its competitiveness is being improved through convergence with cutting-edge electric vehicle (EV) technologies. However, battery-powered vehicles pose difficult technical challenges in attempts to achieve reliable and efficient operation. In this study, a design approach for a solar-power assisted PRT system is presented with small-scale demonstrations aimed at circumventing challenges facing its adoption, as well as helping speed the transition to electric-powered ground transportation. From the results, it is expected that flexible photovoltaic (PV) cells will be able to supply 11% of the power required by the service equipment installed in a prototype vehicle. In particular, flexible photovoltaic (PV) cells are advantageous in terms of cost, weight, and design considerations. Most importantly, the cells' flexibility and attach-ability are expected to give them great potential for extended application in various areas.

• Journal of Life Science
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• v.12 no.1
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• pp.8-15
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• 2002

In this paper we dealt with processing of sausage using duck mechanically deboned meat(duck-MDM). The results may be summarized as follows : 1) after semi-thawing of freezing duck-MDM at $25^{\circ}C$ for 3 hours and cutting as thin, 2) alkali washing at low temperature for 4 hours by 0.2% NaHCO$_3$and 0.15% NaCl, 3) curing at low temperature for 4 hours, 4) after washing and dehydrating(moisture 80%), 5) grinding at low temperature for 55 minutes by silent cutter such as 1st grinding for 10 minutes added only dehydrated meat, 2rd grinding for 30 minutes added salt in 1st grinded meat and 3rd grinding for 15 minutes added other additives, 6) after quick casing in PVDC film and heating at 9$0^{\circ}C$ for 80 minutes, 7) cooling to below room temperature. The additives added at 3rd grinding process were Polymix-CA(0.3%), Polymix-CS(0.3%), polyphosphate(0.3%), sugar(4.2%), potato starch(8.0%), pyre-phosphates(0.3%), isolated soy protein(7.0%), MSG(0.2%), onion powder(0.5%), garlic powder(0.1%), nutmeg (1.5%), potassium sorbate(<0.1%), food red no.40(0.0075%), egg albumin(7.0%) and gluten(3.0%).

• Progress in Medical Physics
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• v.16 no.2
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• pp.82-88
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• 2005

In this study, the physical compensator made with the high density material, Cerrobend, and the electronic compensator realized by the movement of a dynamic multileaf collimator were analyzed in order to verify the properness of a design function in the commercial RTP (radiation treatment planning) system, Eclipse. The CT images of a phantom composed of the regions of five different thickness were acquired and the proper compensator which can make homogeneous dose distribution at the reference depth was designed in the RTP. The frame for the casting of Cerrobend compensator was made with a computerized automatic styrofoam cutting device and the Millennium MLC-120 was used for the electronic compensator. All the dose values and isodose distributions were measured with a radiographic EDR2 film. The deviation of a dose distribution was $\pm0.99 cGy\;and\;\pm1.82cGy$ in each case of a Cerrobend compensator and a electronic compensator compared with a $\pm13.93 cGy$ deviation in an open beam condition. Which showed the proper function of the designed compensators in the view point of a homogeneous dose distribution. When the absolute dose value was analyzed, the Cerrobend compensator showed a $+3.83\%$ error and the electronic compensator showed a $-4.37\%$ error in comparison with a dose value which was calculated in the RTP. These errors can be admtted as an reasonable results that approve the accuracy of the compensator design in the RTP considering the error in the process of the manufacturing of the Cerrobend compensator and the limitation of a film in the absolute dosimetry.

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1523-1528
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• 1999

The consumer's demands for minimally processed fruits and vegetables have been increased rapidly because of its convenient handling, fresh-like quality as well as producing less wastes from the environmental point of view. Asian pears which are one of the main fruits widely produced and consumed in Korea easily lost their characteristics due to browning and softening after cutting. The objective of this study is to investigate the effects of various treatments on delaying deterioration of sliced Asian pears. 'Shingo' pear slices were treated with various solutions $(1%\;NaCl,\;0.2%\;L-cysteine,\;1%\;CaCl_2\;or\;1%\;calcium\;lactate)$ and were packaged with low density polyethylene $(LDPE,\;60\;{\mu}m)$, ceramic $(CE,\;60\;{\mu}m)$ or vacuum $(Ny/PE,\;80\;{\mu}m)$ film at $20^{\circ}C\;and\;0^{\circ}C$. In order to evaluate the quality of packaged sliced pears, quality index was determined in terms of color, firmness, soluble solids, titratable acidity. ascorbic acid, changes of gas composition, microbial test, and sensory quality. The results showed that sliced 'Shingo' pears packaged with CE and vacuum film maintained better quality than with LDPE at $0^{\circ}C\;and\;20^{\circ}C$. To retard browning and softening. 0.2% L-cysteine and 1% NaCl solutions applied for 1 minute were effective to reduce surface browning of sliced pears, and 1% $CaCl_2$ was the most effective to prevent softening.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.28 no.2
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• pp.435-459
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• 1998

In order to achieve a successful endodontic treatment, root canals must be obturated three-dimensionally without causing any damage to apical tissues. Accurate length determination of the root canal is critical in this case. For this reason, I've used the conventional periapical radiography, Digora/sup (R)/(digital imaging system) and Root ZX/sup (R)/(the frequency dependent type apex locator) to measure the length of the canal and compare it with the true length obtained by cutting the tooth in half and measuring the length between the occlusal surface and the apical foramen. From the information obtained by these measurements, I was able to evaluate the accuracy and clinical usefulness of each systems. whether the thickness of files used in endodontic therapy has any effect on the measuring systems was also evaluated in an effort to simplify the treatment planning phase of endodontic treatment. 29 canals of 29 sound premolars were measured with #15, #20, #25 files by 3 different dentists each using the periapical radiography. Digora/sup (R)/ and Root ZX/sup (R)/. The measurements were then compared with the true length. The results were as follows: 1. In comparing mean discrepancies between measurements obtained by using periapical radiography(mean error: -0.449±0.444 mm), Digora/sup (R)/(mean error: -0.417±0.415 mm) and Root ZX/sup (R)/(mean error: 0.123±0.458 mm) with true length. periapical radiography and Digora/sup (R)/ system had statistically significant differences(p<0.05) in most cases while Root ZX/sup (R)/ showed none(p>0.05). 2. By subtracting values obtained by using periapical radiography, Digora/sup (R)/ and Root ZX/sup (R)/ from the true length and making a distribution table of their absolute values. the following analysis was possible. In the case of periapical film. 140 out of 261<53.6％) were clinically acceptable satisfying the margin of error of less than 0.5 mm. 151 out of 261 (53,6％) were acceptable in the Digora/sup (R)/ system while Root ZX/sup (R)/ had 197 out of 261(75.5％) within the limits of 0.5mm margin of error. 3. In determining whether the thickness of files has any effect on measuring methoths, no statistically significant differences were found(p>0.05). 4. In comparing data obtained from these methods in order to evaluate the difference among measuring methods, there was no statistically significant difference between periapical radiography and Digora/sup (R)/ system(p>0.05), but there was statistically significant difference between Root ZX/sup (R)/ and periapical radiography(p<0.05). Also there was statistically significant difference between Root ZX/sup (R)/ and Digora/sup (R)/ system(p<0.05). In conclusion, Root ZX/sup (R)/ was more accurate when compared with the Digora/sup (R)/ system and periapical radiography and seems to be more effective clinically in determining root canal length. But Root ZX/sup (R)/ has its limits in determining root morphology and number of roots and its accuracy becomes questionable when apical foramen is open due to unknown reasons. Therefore the combined use of Root ZX/sup (R)/ and the periapical radiography are mandatory. Digora/sup (R)/ system seems to be more effective when periapical radiographs are needed in a short period of time because of its short processing time and less exposure.

• Journal of The Korean Society of Grassland and Forage Science
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• v.15 no.3
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• pp.198-206
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• 1995

Baled silage making(BS) of selected forage crops was discussed during 1991-1993, to determine the best cutting time of the plants for BS production, BS yields and silage quality. Seven species of forage crops and pasture grasses(rye, barley, spring oat, Italian ryegrass, orchardgrass, alfalfa and grass-legume pasture mixtures) were harvested at different stage of growth from young plant to physiological maturity, and baled in a self constructed square baling chamber. Each bales, measured 90cm length, 60cm width and 50cm height, were wrapped with 0.05mrn thick polyethylene plastic film, and stored in stack silo. Each bales were weighed between 15-20 kg in dry matter basis. The effects of pre wilting and formic acid addition on the silage quality of young plant materials, which contained high water concentration, was also evaluated during the experiment. Rye plant including of barley and spring oat were evaluated as a good materials for baled silage making. Fodder rye produced high quality BS with a value of silage quality point 84(Flieg's point) when the plant harvested at stage of greatest dry matter accumulation by 12.64 tonha. The best quality BS of barley was obtained at stage of hard dough to yellow stage by 11.9 ton/ha dry matter yield and 81 point silage quality. Italian ryegrass and pasture grasses including of orchardgrass, alfalfa and grass-legume pasture mixtures procuced also high quality bale silage by harvesting at stage of late blooming. However pre witting operation and formic acid addition was required for BS production of grass materials because of high water contents. Water contents of Italian ryegrass and other pasture species ranged 18.9%(Italian) to 20.8%(alfalfa). Silage quality point of Italian BS harvested at late blooing was increased from 72 to 88 by 1/2-one day pre wilting and 0.3% formic acid treatment. Silage quality of young plant materials of rye and other forage crops, barley and spring oat were also improved markedly through the pre wilting treatment and formic acid addition.

• Journal of Bio-Environment Control
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• v.20 no.4
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• pp.406-411
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• 2011

This study was conducted to find out the effect of cut-off period (0 hour, 3 hours, 6 hours, 12 hours, and 24 hours) to supply nutrient solution for chicon forcing at that was predrying treatment on the storability of chicon. The cut-off treatment increased dry matter rate, respiration rate, and ethylene production rate. The dry matter rate of chicon increased, as the cut-off period increased, but the respiration rate and ethylene production rate of chicon was highest in 12 hours and 6 hours cut-off treatment, respectively, and then their rates decreased, as the cut-off period prolonged. The weight loss at cut-off 6 hours treatment was lower than other treatments during $10^{\circ}C$ storage temperature. The cut-off 6 hours treatment showed higher carbon dioxide and oxygen concentration in 10,000 cc/$m^2$/day/atm oxygen permeability film package during storage period than control and showed a little predrying effect but was not statistically significant. At $4^{th}$ day, the ethylene concentration reached higher than other storage day and after that decreased but was not statistically significant. The quality of chicon for 3 hours, 6 hours, 24 hours cut-off treatments on storability showed higher than other treatments, accordingly. The 6 hours cut-off treatment showed the inhibited effect of the degree of browning of chicon cutting plane. The effect of 6 hours cut-off treatment on storability of chicon showed proper predrying effect, reduced moisture loss and browning inhibition apparently during $10^{\circ}C$ storage.

• 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.