• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.7
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• pp.1324-1331
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• 2002

Densification behavior of composite powders was investigated during cold compaction. Experimental data were obtained for aluminum alloy powder mixed with zirconia powder inclusion under triaxial compression. The Cap model with constraint factors was implemented into a finite element program (ABAQUS) to simulate compaction responses of composite powders during cold compaction. Finite element results were compared with experimental data for densification behavior of composite powders under cold isostatic pressing and die compaction. The agreements between experimental data and finite element calculations from the Cap model with constraint factors were good.

• Elastomers and Composites
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• v.43 no.2
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• pp.124-132
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• 2008

Thermal and mechanical properties of flexible polyurethane foam modified by urushiol and cardanol which have been known to be antibiotic were investigated. It was observed from FT-IR spectra analysis that the urushiol reacted with isocyanate was participated in synthesis of polyurethane. It was also seen that the modification using urushiol and cardanol made the PU more thermally stable without deterioration of mechanical properties. The modified PU foams showed increased antibacterial properties compared with neat PU foam.

• Korean Journal of Food Science and Technology
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• v.33 no.6
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• pp.769-773
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• 2001

Protein content of okara and soybean were found to be 37.3% and 42.5%, respectively by micro-Kjeldahl analysis. Solubility of okara protein in phosphate buffer (pH 8) was 10% versus soy protein of 68.4%. Insolubilization of okara protein was mostly due to disulfide bonding between cysteine residues caused by excessive heat treatment during soymilk processing: hydrophobic interactions and hydrogen bondings were involved to lesser extent. Optimum extraction temperature and time were $60^{\circ}C$ and 40 min. Typical solubility profile of soy protein disappeared for okara protein though minimum solubility of the protein was around pH 3.0. Treating okara with protease was effective in solubilizing okara protein and solubility increased to 19.2%. Optimum reaction temperature and time were $80^{\circ}C$ and 50 min, respectively. Cell wall degrading enzyme did not increase solubility of the protein, however. Through enzymatic reaction okara protein could be effectively solubilized for uses as food ingredient.

• Korean Journal of Food Science and Technology
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• v.46 no.1
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• pp.39-43
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• 2014

The antimicrobial activity of Orixa japonica Thunb. leaf extract towards 13 microorganism strains was evaluated. Both methanol (MEex) and 70% ethanol extracts showed antimicrobial activity towards Streptococcus mutans, Bacillus cereus, Staphylococcus aureus, and Pseudomonas aeruginosa. MEex showed a higher antimicrobial activity than the 70% ethanol extract. In addition, the dichloromethane fraction (DCMfr) of the MEex also had an antimicrobial effect against the microorganisms examined. The minimum inhibitory concentrations (MICs) towards S. mutans, B. cereus, S. aureus, and P. aeruginosa were 49.22, 24.61, 49.22, and 49.22 mg/mL, respectively. In contrast, the MICs of the DCMfr tpwards S. mutans, B. cereus, S. aureus, and P. aeruginosa were 3.31, 0.21, 1.7, and 1.7 mg/mL, respectively. The MEex antimicrobial activity was not affected by a 3 h exposures to pH in the range of 3-11 or by temperatures were maintained between $80^{\circ}C-100^{\circ}C$ for 6 h. However, the MEex antimicrobial activity decreased at a heat treatment of $121^{\circ}C$ 1 h.

• Journal of Adhesion and Interface
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• v.22 no.4
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• pp.136-143
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• 2021

Polyurea has been investigated as a polymer matrix for composite materials because of its high mechanical strength. Although polyurea has a similar chemical structure to polyurethane, it has much higher strength and durability. In this study, the fabrication of polyurea composites reinforced with carbon nanotube (CNT) and graphene oxide (GO) is demonstrated to enhance the tensile strength of the glass fibers composite. Using FTIR and Raman spectroscopies, the chemical structures of polyurea, CNT, and GO are investigated. As a result, spectroscopy analysis reveals that the chemical structure of CNT, GO, and polyurea is maintained during the fabrication of the composite structure. Scanning electron microscopy reveals the uniform distribution of CNT and GO across the polyurea matrix. The reinforcement of 1 wt% CNT in polyurea enhances the tensile strength of CNT/polyurea composites. In contrast, the reinforcement of GO in polyurea induces the degradation of the tensile strength of GO/polyurea composites.