• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.2
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• pp.238-244
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• 2003

With the purpose of evaluating the effect of ailing amount of pit and assure sealants on the microleakage, 6 groups of specimens with different filling amount, filling materials and surface pretreatment were investigated. Sixty permanent third molars were divided into three groups. The occlusal surface of each tooth was divided into two parts; the filing width of one part was below 1mm (group1, 3, 5), and in the other part more than 2mm (group 2, 4, 6) Group 1 and 2: Helioseal F was applied directly to etched enamel; Group 3 and 4: Helioseal F was applied to etched and scotchbond Multi-purpose plus pre-treated enamel; Group 5 and 6: Tetric Flow was applied. After 500 times thermocycling and dye infiltration, we evaulated the microleakage. The results were as follows; 1. The mean microleakage score at each width were increased in the following order;group 5<3<1, and group 6<4<2. 2. In comparing the groups with same material and surface pretreatment but with different filling width (group 1 versus 2, 3 versus 4, 5 versus 6), the microleakage scores were significantly different. 3 The microleage was affected by filling amount of pit and assure sealants than Oiling materials and dentin bonding agent pretreatment.

• Journal of the Korean Geosynthetics Society
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• v.18 no.1
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• pp.67-77
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• 2019

The grouting method is utilized to reinforce and waterproof poor grounds, enhance the bearing capacity of structures damaged resulting from settlement due to elevation and vibration or differential settlement, and for cutoff. The purpose of this research is to enhance the compressive strength of grout materials by using aramid fiber and develop a high-strength ground improvement method by using blast furnace slag powder. In this regard, this study has conducted a uniaxial compression test after checking the high charge (higher than 50%) of the ratio of blast furnace slag powder and cement at 100:0, 70:30 and 40:60%, adding the aramid mixture based on 0, 0.5 and 1.0% of the cement and furnace slag powder weight and creating sand gels based on surface oiling rate of 0.7 and 1.2%. For the environmental review evaluation, a heavy metal exudation test and a pH test measurement have been conducted. The experiment results showed that 1% increase of aramid fiber led to 1.3 times greater uniaxial compression intensity. As for the hexavalent chrome, a 30% increase in blast furnace slag powder led to approximately 50% decrease in heavy metal exudation. However, the pH test revealed that a 30% increase in blast furnace slag powder resulted in approximately 0.5 increase in pH. Further research on the pH part is needed in the future.

• Food Science and Preservation
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• v.16 no.3
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• pp.405-411
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• 2009

The manufacturing process and quality properties of Lactococcus lactis-fermented yakchobugak (LFY) containing some colored agro-food products were investigated to develop a good organoleptic bugak from the leaf of the medicinal herb. The de-oiling rate of LFY by centrifugation was 37.6%, which was significantly different to the 3.5% value obtained after standing and the 8.9% value obtained with the beating method (p<0.05). Reducing power (RS) increased with addition of increasing levels of ethanol extracts from agro-food powders. The RS of green tea extract-supplemented LFY had the highest value of 0.97 at $500{\mu}g/mL$, and this was significantly different to values obtained using other extracts (p<0.05). At 83.84%, the DPPH (2,2-diphenyl-1-picrylhydrazyl) free-radical scavenging activity of green tea extract-supplemented LFY was the greatest of all samples tested, followed by LFY with woolgeom at 39.48%, LFY with black rice at 28.45%, and LFY with bokbunja at 22.24% all ethanol extracts were added at $50{\mu}g/mL$ (p<0.05). Acid values of green tea and bokbunja LFYs stored in transparent PE bags at $60^{\circ}C$ for 7 days were 1.82% and 2.03%, respectively. Textural hardness values of LFYs were less than 250.62, except for LFYs with black rice and woolgeom, but these values increased $2{\sim}3$-fold after lactic acid fermentation. Carbohydrate and protein content of LFYs were in the ranges $58.95{\sim}64.63%$ and $7.50{\sim}8.68%$, respectively. Lipid and calorie contents of woolgeom LFY had the lowest values of 22.02% and 490 Kcal, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.667-678
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• 2002

In this paper, a new radiating structure with a multi-layered two-dimensional metallic disk array was proposed for shaping the flat-topped element pattern. It is an infinite periodic planar array structure with metallic disks finitely stacked above the radiating circular waveguide apertures. The theoretical analysis was in detail performed using rigid full-wave analysis, and was based on modal representations for the fields in the partial regions of the array structure and for the currents on the metallic disks. The final system of linear algebraic equations was derived using the orthogonal property of vector wave functions, mode-matching method, boundary conditions and Galerkin's method, and also their unknown modal coefficients needed for calculation of the array characteristics were determined by Gauss elimination method. The application of the algorithm was demonstrated in an array design for shaping the flat-topped element patterns of $\pm$20$^{\circ}$ beam width in Ka-band. The optimal design parameters normalized by a wavelength for general applications are presented, which are obtained through optimization process on the basis of simulation and design experience. A Ka-band experimental breadboard with symmetric nineteen elements was fabricated to compare simulation results with experimental results. The metallic disks array structure stacked above the radiating circular waveguide apertures was realized using ion-beam deposition method on thin polymer films. It was shown that the calculated and measured element patterns of the breadboard were in very close agreement within the beam scanning range. The result analysis for side lobe and grating lobe was done, and also a blindness phenomenon was discussed, which may cause by multi-layered metallic disk structure at the broadside. Input VSWR of the breadboard was less than 1.14, and its gains measured at 29.0 GHz. 29.5 GHz and 30 GHz were 10.2 dB, 10.0 dB and 10.7 dB, respectively. The experimental and simulation results showed that the proposed multi-layered metallic disk array structure could shape the efficient flat-topped element pattern.