• Journal of Sericultural and Entomological Science
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• v.28 no.1
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• pp.66-71
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• 1986

The studies were carried out to screen the optimum conditions for enzymatic degumming of raw silk yarn and silk fabric by use of Alkalase, a protease produced by Bacteria, comparing with Papain and Trypsin representing natural proteolytic enzymes. 1. The optimum temperature and acidity of degumming solution were 70$^{\circ}C$, pH 5-6 for Papain degumming, 40$^{\circ}C$, pH 8 for Trypsin and 50-60$^{\circ}C$ pH 8-9 for Alkalase. 2. By increasing the Alkalase concentration in the range of 0.6 to 1.0 gram per liter, the time for enzymatic degumming of silk yarn could be reduced by 40 minutes. 3. In degumming of silk yarn by Alkalase, the pretreatment of 95$^{\circ}C$, 10 minutes at 0.1% sodium bicarbonate solution or posttreatent of 80$^{\circ}C$, 20 minutes at 2% (o.w.f.) sodium silicate solution improved the efficiency of enzymatic degumming, as compared to that of nontreatment. 4. The breaking strength, elongation and Lousiness results of enzymatically degummed silk yarn were apt to be improved more than those of soap-degummed one. 5. When the pretreatment of alkaline solution was done with over 20% of degumming ratio, the enzymatic degumming efficiency of both Havutae and Crepe de chine could be reached to the same level with those of soap-soda degummed. 6. As the pretreated silk fabric with 20% of degumming ratio was under action of three proteases, respectively, the deumming efficiency of Havutae and Crepe de chine were completed by Alkalase more than by Papain or Trpysin. 7. The stiffness of enzymatically degummed Crepe de chine was not only reduced by 17% more than that of soap-soda degummed one but also the Drape coefficient was decreased in enzymatically degummed fabrics, which was closely related with the soft touch of degummed fabrics.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.3
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• pp.111-122
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• 2021

Purpose: The purpose of this in vitro study was to investigate the flexural strength and translucency of three layers in 5Y-ZP and to assess the effect of additional firings on these properties. Materials and Methods: Sintered zirconia blocks were sectioned according to three layers : incisal, transition, and body. Disc-shaped specimens were fabricated from each layer. The diameter of specimens was 15.0 mm and each thickness of specimens for biaxial flexural strength test and translucency was 1.2 mm and 1.0 mm. The specimens were classified into subgroups according to the number of firing (0, 1, and 3 times; n = 10/subgroup) and the additional firings were performed under 900℃ using a furnace. Biaxial flexural strength and translucency was measured using universal testing machine and uv-vis spectrophotometer. X-ray diffraction (XRD) analysis was used for measurement of the phase identification. One-way ANOVA, Tukey HSD test were performed (α = 0.05). Results: There was no significant difference in flexural strength between the three layers (P > 0.05), while there was significant difference in translucency between different layers (P < 0.05). The flexural strength of incisal and transition layer was decreased by the single additional firing, and the three additional firings significantly decreased the flexural strength of three layers. The translucency of layer was decreased by additional firings except the body layer. The XRD patterns of all groups were similar. Conclusion: Three layers of 5Y-ZP were different only in translucency. Additional firings affected the flexural strength and translucency differently depending on the layers but crystalline phases were not changed.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1134-1144
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• 2018

Cetane Number is one of the quality standard for diesel, which assesses the compatibility of ignition quality of diesel compression in diesel engines. Cetane number must be upper 52 to keep the recent diesel quality standards. It is known that if cetane number is high, there will be shorter ignition delay periods than being lower. On the other hands, if cetane number is too high that exceeds the quality standard, there will increase the air pollution and decrease of the fuel efficiency because incomplete combustion. In South Korea, various methods are being used to measure the cetane number such as cetane number that used CFR engine, cetane index from calculate density and distillation temperature and derived cetane number to make up for CFR engine that ignition delay in high temperature is implemented. In this study will be conducted by collecting the diesel from the major oil companies, and try to analyze the correlation between the different methods of cetane number with various factors. At the results of this study, it was shown that the cetane index is high then cetane engine and derived cetane number. therefore it will be necessary to additional research for out of cetane number quality standards.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.687-694
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• 2019

In order to investigate the behavior of limestones which have been usually used for in-situ desulfurization reaction in circulating fluidized bed combustors, the attrition characteristics and calcination reactions of domestic limestones were analyzed in this study by using a thermogravimetric analyzer and an ASTM D5757-95 attrition tester. The average size distribution of limestones in circulating fluidized bed boilers have to be changed due to the attrition of particle-particle and particle-reactor wall and the calcination reaction. Domestic limestones might be used in commercial circulating fluidized bed boilers, but the attrition behaviors and particle size changes of limestones were varied. In calcination experiments at $850^{\circ}C$, the calcination reaction were varied with limestone samples. The calcination reaction time increased with an increase of particle size. Also, fine particles generated the attrition test of calcined limestone was 20% higher than those generated the attrition test of original limestone.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.1
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• pp.87-93
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• 2019

This study attempted to eatablish a High Performance Liquid Chromatography (HPLC) analysis method for the determination of (-)-epicatechin gallate as a part of the quality control for the development of functional cosmetic materials from Penthorum chinense Pursh. HPLC was performed on a Unison $US-C_{18}$ column ($4.6{\times}250mm$, $5{\mu}m$) with a gradient elution of 0.05% (v/v) trifluoroacetic acid (TFA) and methyl alcohol at a flow rate of 1.0 mL/min at $30^{\circ}C$. The analyte was detected at 280 nm. The HPLC method was performed in accordance with the International Conference on Harmonization (ICH) guideline (version 4, 2005) of analytical procedures with respect to specificity, precision, accuracy, and linearity. The limits of detection and quantitation were 0.11 and 0.33 mg/mL, respectively. Calibration curves showed good linearity ($r^2$ > 0.9999), and the precision of analysis was satisfied (less than 0.6%). Recoveries of quantified compounds ranged from 99.51 to 101.92%. This result indicates that the established HPLC method is very useful for the determination of marker compound in P. chinense Pursh extracts.

• Applied Chemistry for Engineering
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• v.30 no.3
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• pp.371-378
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• 2019

Graphene nanoplatelet (GnP)/reused phenolic foam (re-PF)/wood composite boards were fabricated with different GnP content as 5, 10 and 20 w/w% to investigate the effect of GnP on thermal- and flame retardant properties of wood-based composite boards. The thermal- and flame retardant properties of fabricated composite boards were investigated by thermogravimetric analysis (TGA) and limiting oxygen index (LOI), respectively. The thermal stability of the composite boards increased proportionally with respect to the amount of GnP, and the char yield of these boards increased up to 22% compared to that of the pure wood board. The LOI values of composite boards were about 4.8~7.8% higher than those of using pure wood boards. It was also confirmed that the flame retardant properties of composite boards were remarkably improved by the addition of re-PF and GnP. These results were because of the fact that the re-PF and GnP with a high thermal stability delayed the initial thermal degradation temperature of composite boards and made their char layers denser and thicker which led the overall combustion delay effect of the composite board. Especially, GnP as a carbon-based material, facilitated the char layer formation and increased remarkedly the char yield, which showed higher effect on flame retardant properties than those of the re-PF.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.5
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• pp.303-314
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• 2021

With the high quality/high stiffness/high strength of segment lining, segment lining is increasingly used as the final lining of the tunnel. Precast concrete lining has higher quality and strength than field concrete. Paradoxically, this contributes to greater damage to concrete in the event of a fire in a tunnel. In this study, tests were conducted to determine the fire resistance performance of segment linings according to fiber content in fire resistance methods using synthetic fibers such as PP fibers. As a result, it was confirmed that fire resistance performance required by the relevant project can be secured when using 1.5 kg/m³ of PP fiber. In addition, comparison of the results of PP fibers with PET, a similar synthetic fiber, showed better fire resistance performance than when PP fibers were used.

• Journal of Mushroom
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• v.19 no.2
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• pp.96-102
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• 2021

A new cultivar of oak mushroom 'Dadam' was bred from monokaryotic strains of 'GMLE36062-4' and 'GMLE36288-34'. The optimum temperature for mycelial growth of the new cultivar 'Dadam' on potato dextrose agar was 19-22℃. Total cultivation period of the new cultivar, from innoculation to its first harvest, was 135-139 days, similar to that of the control cultivar 'Hwadam'. The pileus color and stipe thickness of the new cultivar were darker and thinner than those of 'Hwadam'. Total yield of 'Dadam' was 621 g per 3 kg substrate, and is higher than that of 'Hwadam' (371 g). In farmhouse field test, it showed that the period of mycelial growth, browning, and fruiting body formation were the same as those of the control cultivar L808. The number of available fruiting bodies of 'Dadam' was 15, and is lower than that of the control (47), therefore, it was possible to save workforce in thinning. The total yield for 2 flush was 480 g for 'Dadam', similar to the 473 g of the control cultivar.

• Journal of The Korean Society of Grassland and Forage Science
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• v.41 no.2
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• pp.134-140
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• 2021

This study was carried out to study the effect of supplementary nitrogen fertilization application time according to regrowth date on growth date on growth characteristics, feed value, and productivity of Italian ryegrass (Lolium multiflorum Lam.; IRG) from 2019 to 2021 in Cheonan region. In order to determine the regrowth time, IRG was cut from experimental plots 3cm above soil level and the time when 1cm grew was judged as the regrowth time. The regrowth dates were February 15^th and February 12th in 2020 and 2021 respectively. The experimental design was a randomized block design with three replications. The treatments were no fertilizer, immediately after the regrowth period, after 10 days of the regrowth period, and after 25 days of the regrowth period. Dry matter yield of IRG was significantly influenced by the supplementary N-fertilization application time. Dry matter yield was reduced for the delayed application time. The dry matter yield of immediately after the regrowth period was approximately 34.8 % higher than that no fertilizer application. In delaying the supplementary N-fertilization application time resulted in increased crude protein content. However, no significant statistical difference was neutral detergent fiber and acid detergent fiber(p>0.05). After wintering, productivity of IRG reduced for the delayed application time. Therefore, it is essential to application N-fertilizer immediately after the regrowth period for high productivity of IRG.

• Composites Research
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• v.33 no.6
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• pp.365-370
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• 2020

The icing formation at aircraft occur problems such as increasing weight of the body, fuel efficiency reduction, drag reduction, the error of sensor, and etc. The viscosity of polyurethane (PU) topcoat was measured at 60℃ in real time to set the pre-curing time. SiO2 nanoparticles were dispersed in ethanol using ultra-sonication method. The SiO2/ethanol solution was sprayed on PU topcoat that was not cured fully with different pre-curing conditions. Surface roughness of SiO2/PU nanocomposites were measured using surface roughness tester and the surface roughness data was visualized using 3D mapping. The adhesion property between SiO2 and PU topcoat was evaluated using adhesion pull-off test. The static contact angle was measured using distilled water to evaluate the hydrophobicity. Finally, the pre-curing time of PU topcoat was optimized to exhibit the hydrophobicity of SiO2/PU topcoat.