• Applied Chemistry for Engineering
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• v.20 no.3
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• pp.258-265
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• 2009

An anionic polyurethane dispersions (PUDs) were synthesized from the poly (tetramethylene glycol) (PTMG, Mw = 2000 g/mol), mixed isocyanate of dicyclohexylmethane-4,4'-diisocyanate $(H_{12}-MDI)$ and 4,4'-diphenylmethane diisocyanate (MDI), and dimethylol propionic acid (DMPA) as anionic site, following a prepolymer mixing process. Triethylamine (TEA) was used as a neutralization agent and the ethylenediamine (EDA) as the chain extender of the prepolymer. The effects of the DMPA molar ratio and aromatic diisocyanate content in the mixed isocyanate on the particle size and viscosity of PUD were studied. Also, the mechanical and thermal properties of the PUD cast films were discussed according to the molar ratio of DMPA and aromatic isocyanate content. It was found that the particle size and the viscosity of an anionic PUD decreased with increasing DMPA molar ratio but increased with increasing aromatic isocyanate (MDI) content in the mixed isocyanate at the constant DMPA content. Tensile strength of the PUD cast films increased and elongation at break decreased with increasing DMPA content at the constant mixed isocyanate molar ratios. In thermal degradation temperature of PUD cast films, the effect of DMPA contents was great but the effect of aromatic isocyanate contents at the low DMPA content was very slight respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.2
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• pp.268-274
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• 2015

Makgeolli residue protein (MRP) was extracted from byproduct of makgeolli processing, and MRP films containing various plasticizers were prepared. Among the plasticizers used in this study, MRP film containing glycerol-sorbitol (1:2) showed the most desirable mechanical properties. In addition, MRP films containing wasabi extract (WE) were prepared by incorporating different amounts (0, 0.8, 1.0, and 1.2%) of WE into film-forming solution. Tensile strength, elongation at break, and moisture content of MRP films decreased with addition of WE as compared with the control. However, MRP films containing WE showed antimicrobial activities against Escherichia coli O157:H7 and Listeria monocytogenes. Application of MRP film containing 1.0% WE to beef packaging decreased populations of E. coli O157:H7 and L. monocytogenes after storage at $4^{\circ}C$ for 8 days by 1.1 and 0.41 log CFU/g, respectively, compared with those of the control. In addition, the peroxide value and 2-thiobarbituric acid reactive substance value decreased by 53 and 56%, respectively, compared to the control. Therefore, these results suggest that MRP film containing WE can be used to improve the quality of beef during storage.

• Korean Journal of Food Science and Technology
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• v.43 no.1
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• pp.30-38
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• 2011

Effects of depolymerization treatments of a carbohydrase mixture (CM), ultrasound, and irradiation on the physical properties of defatted mustard meal-based edible films (DMM films) were investigated. DMM hydrocolloids were added to CM (0.42% (w/w solution)), treated by ultrasound (500-700 W, 10-30 min) or ${\gamma}$-ray (40-100 kGy) to prepare film-forming solutions. Films were formed by drying. The CM treatment at 0.42% (w/w), pH 5.5, and 40-$50^{\circ}C$ with a 0.5 hr incubation time resulted in the highest colloidal stability in the film-forming solution. The depolymerization treatments did not dramatically change the water vapor permeability of the films. The solubility of the film decreased up to 53.1% by the CM treatment. The ultrasound treatment (700 W-30 min) decreased tensile strength and elongation. The ultrasound treatment (600 W-20 min) resulted in more compact and uniform structures of the films. Flavor profiles were differentiated by the power level and the time of the ultrasound treatment.

• Journal of Sericultural and Entomological Science
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• v.26 no.2
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• pp.16-25
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• 1984

The sericin fixation of silk fabrics by epoxy resins was studied in the presence of aqueous salt solution in different solvents at the indicated temperature for the desired time. Heavy weight gains were obtained in the reaction with glycerol diglycidyl ether (EX-313) and ethylene glycol diglycidyl ether (EX-810) catalyzed by potassium thiocyanate in such solvents as carbon tetrachloride and p-chloroethylene. The obtained results were summarized as follows; 1) The tested resins were found similar in reaction behavior to silk fabric. The effect of fixation and weight gains was higher in EX-810 than EX-313. 2) The weight gains were increased with reaction time and temperature, and degumming ratio reached a constant value in 90 min at 70$^{\circ}C$. 3) The weight gains and the degumming ratio reached an equilibrium at 3-5% of epoxy concentration. 4) The weight gains were remarkably influenced and increased by the concentration of salt solution. The degumming ratio reached an equilibrium over 0.5N concentration of salt. 5) The weight gains were increased with the dipping time in gently-sloping. The degumming ratio reached an equilibrium over 15 min dipping. 6) The effect of sericin fixation of hydrophobic solvents, such as Carbon Tetrachloride, p-Chloroeth-ylene, Cyclohexane, Xylene and Toluene, was found suitable. 7) The effect of drying temperature was not remarkable on the weight gains and the degumming ratio. 8) There was a slight decrease in the moisture regain of sericin-fixed silk and it may be possible to maintain the moisture regain in the sericin-fixed silk by the epoxy resins. 9) The results on testing physical properties of sericin-fixed silk fabric were as follows; The crease recovery was almost not different from undegummed fabric, but inferior to degummed fabric. The tensile strength was improving in accordance with the effect of sericin fixation, either the elongation did.

• Korean Journal of Food Science and Technology
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• v.36 no.3
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• pp.432-439
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• 2004

Increase in water vapor barrier properties of sodium alginate films was studied by preparing composite films with fatty acids, i.e., lauric, palmitic, stearic, and oleic acids, and by treatment with 3% $CaCl_{2}$ solution for 3 min. Film thickness, surface color, microstructure, tensile strength (TS), elongation at break (E), water vapor permeability (WVP), water solubility (WS), and sorption isotherm of films were investigated. Microstructure of films observed with SEM was changed by fatty acid and $CaCl_{2}$ treatments. TS decreased 25-70% depending on fatty acid used, and increased 1.5- to 2-fold by $CaCl_{2}$ treatment. E decreased by both fatty acid and $CaCl_{2}$ treatments. Except oleic acid, WVP decreased significantly (p<0.05) by forming composite films with fatty acids, particularly with stearic acid, WVP decreased more than two-fold. WS also decreased by fatty acid and $CaCl_{2}$ treatments. In stearic acid, WS decreased about 30-fold by combined treatment of fatty acid and $CaCl_{2}$. Sorption isotherm showed typical biphasic pattern with deliquescent point of 0.75. Results of isotherms and BET monolayer moisture content indicated hydrophilicity of film decreased by $CaCl_{2}$ treatment.

• Journal of Applied Biological Chemistry
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• v.58 no.2
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• pp.145-151
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• 2015

Corn fiber protein (CFP) was extracted from corn wet-milling by-product, corn fiber. CFP films containing various plasticizers and cross-linking agents were prepared and their mechanical properties were determined. Among the plasticizers and cross-linking agents used in this study, the CFP film containing 2 g fructose and 0.03% cinnamaldehyde had the most appropriate physical property. In addition, the CFP films containing green tea extract (GTE) were prepared by incorporating different amounts (0, 0.5, 1.0, 1.5%) of GTE into the film-forming solution. Tensile strength, film solubility, and opacity of the CFP films increased with the addition of GTE, whereas elongation and water vapor permeability of the CFP/GTE films decreased compared to those of the control. The antioxidant activity of the CFP/GTE film was determined in terms of 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity. As a result, antioxidant activity of the films increased with increasing GTE concentration. Furthermore, antimicrobial activity against Escherichia coli O157:H7, Listeria monocytogenes, and Staphylococcus aureus increased with increasing GTE concentration. These results indicate that the incorporation of GTE could enhance antioxidant and antimicrobial activities of the CFP films.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.285-291
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• 2016

The purpose of this study was to evaluate the structural capacity of steel pipe pile specimens reinforced with hollow steel plate shear connectors by pull-out test. Compressive strength testing of concrete was conducted and yield forces, tensile strengths and elongation ratios of re-bars and hollow steel plate were investigated. A 2,000kN capacity UTM was used for the pull-out test with 0.01mm/sec velocity by displacement control method. Strain gauges were installed at the center of re-bars and hollow steel plates and LVDTs were also installed to measure the relative displacement between the loading plate and in-filled concrete pile specimens. The yield forces of the steel pipe pile specimens reinforced with hollow steel plate shear connectors were increased 1.44-fold and 1.53-fold compared to that of a control specimen, respectively. Limited state forces of steel pipe pile specimens reinforced with hollow steel plate shear connectors were increased 1.23-fold and 1.29-fold compared to that of a control specimen, respectively. Yield state displacement and limited state displacement of steel pipe pile specimens reinforced with hollow steel plate shear connector were decreased 0.61-fold and 0.42-fold compared to that of a control specimen, respectively.

• Elastomers and Composites
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• v.49 no.1
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• pp.24-30
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• 2014

3-Amino-1,2,4-triazole (ATA) (2.5 and 5.0 phr) was incorporated into a immiscible maleated ethylene propylene diene rubber(mEPDM)/maleated high density polyethylene(mHDPE) (50 wt%/50 wt%) blend by melt mixing. Effects of the ATA on structure, mechanical and rheological properties of the blend was investigated. FT-IR and DMA results revealed that supramolecular hydrogen bonding interactions between the polymer chains occur by reaction of ATA with maleic anhydride grafted onto the component polymers in the blend, which induces the physical crosslinks in the blend. FE-SEM analysis showed that mEPDM forms a dispersed phase in continuous mHDPE matrix, and the blend with the ATA has finer phase morphology as compared to the blend without the ATA. By the addition of ATA in the blend, there were significant increases in tensile strength, modulus and elongation-at-break as well as elastic recoverability. Melt rheology studies revealed that ATA induced substantial increase in storage modulus and complex viscosity of the blend at the melt state.

• Korean Journal of Materials Research
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• v.22 no.1
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• pp.46-53
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• 2012

In this study, mechanical tests and microstructural analyses including TEM analyses with EDX of precipitates in modified 9Cr-1Mo steel were carried out to determine the cause of embrittlement observed after heat-treatment, which limits the usage of the alloy for power plants. Mod. 9Cr-1Mo steel specimens at austenite temperature were quenched to the molten salt baths at $760^{\circ}C$ and $700^{\circ}C$, in which the specimens were kept for 10 min ~ 10 hr with subsequent air-cooling. Impact tests showed that the impact value dropped abruptly when the specimens were kept longer than 30 min at $\sim760^{\circ}C$ reaching to minima in about 1 hr, and then increasing at further retention. The tensile strength of the specimens reached the minimum value without much change afterward, whereas the values of elongation showed the same trend as that of the impact value. The isothermally heat-treated steel at $700^{\circ}C$ also showed a minimum impact value in about 1 hr. These results suggest that the isothermal heattreatment at 760 and $700^{\circ}C$ for about 1 hr induces temporal embrittlement in Mod. 9Cr-1Mo steel. The microstructural examination of all the specimens with extraction replica of the carbides revealed that the specimens with temporal embrittlement had $Cr_2C$, indicating that the cause of the embrittlement was the precipitation of the $Cr_2C$. In addition, TEM/EDX results showed that the Fe/Cr ratio was 0.033 to 0.055 for $Cr_2C$, whereas it was 0.48 to 0.75 for $Cr_{23}C_6$, making the distinction of the $Cr_2C$ and $Cr_{23}C_6$ possible even without direct electron diffraction analyses.

• Polymer(Korea)
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• v.33 no.5
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• pp.446-451
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• 2009

Reliability evaluations of linear low density polyethylene (LLDPE) pipe with respect of thermal exposure time have been investigated in accordance with RS M 0042, which is a reliability standard for polymer pipe. As the thermal exposure time is prolonged, a progressive increase, until 250 days, in tensile strength and a slight increase in hardness are observed, while a proportional decrease in elongation at break is showed. These results can be explained by the increase of crystallinity, followed by the increase of crosslinking density, chain scission and the decrease in chain mobility, due to thermal oxidation as the exposure time increases. Long term hydrostatic pressure test result implies the existence of transition point from ductile to brittle fracture. Oxidation induction time (OIT) test is employed to monitor the thermo-oxidative degradation of LLDPE pipe. This result shows that after the exposure time is 250 days, the depletion of antioxidants added in LLDPE pipe occurs. An empirical equation as function of exposure time, under $100^{\circ}C$ thermal-degradation condition, is proposed to assess the remaining amount of antioxidants owing to thermo-oxidative degradation. Fourier transform infrared spectroscopy results show the increase of carbonyl (-C=O) and hydroxyl (O-H) function groups on the surface of thermally exposed LLDPE pipe. This result suggests that the hydrocarbon groups locally undergo the oxidation on the LLDPE surface due to thermal-degradation.