• Journal of Adhesion and Interface
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• v.20 no.3
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• pp.87-95
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• 2019

In the present study, the effect of alkali treatment of rice straw on the flexural properties and impact strength of rice straw/recycled polyethylene composite was investigated. Alkali treatments were performed by means of two different methods at various sodium hydroxide (NaOH) concentrations. One is static soaking method and the other is dynamic shaking method. The composites were made by compression molding technique using rice straw/recycled polyethylene pellets produced by twin-screw extrusion process. The result strongly depends on the alkali treatment method and concentration. The shaking method done with a low concentration of 1 wt% NaOH exhibits the highest flexural and impact properties whereas the soaking method done with a high concentration of 10 wt% NaOH exhibits the highest properties, being supported qualitatively by the fiber-matrix interfacial bonding of the composites. The properties between the two highest property cases above-described are comparable each other. The study suggests that such a low concentration of 1 wt% NaOH may be used for alkali treatment of natural fibers to improve the flexural and impact properties of resulting composites, rather than using high concentrations of NaOH, 10 wt% or higher. Considering of environmental concerns of alkali treatment, the shaking method is preferable to use.

• Food Engineering Progress
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• v.15 no.2
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• pp.155-161
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• 2011

The aim of this study was to determine the effects of different extrusion conditions on the saccharification characteristics( initial reaction velocity, reaction rate constant, yield) of extruded corn starch. Extruded corn starch-water slurries were mixed with alpha-amylase for the enzymatic saccharification. The saccharification yield of extruded corn starch was high at lower feed moisture content and higher barrel temperature. The solubility of extrudates increased with increase in the SME input which increased with increase in the feed moisture content. Starch hydrolysates having DE 63.8 was obtained after 2 hr reaction. The initial reaction velocity of the extrudate slurry with alpha-amylase was higher with decrease in the feed moisture content. The initial reaction velocity of extruded corn starch was the highest ($2.26{\times}10^{-3}mmol/mL{\cdot}min$) at 25% feed moisture content and $120^{\circ}C$ barrel temperature, 250 rpm screw speed. The pregelatinized starch was $1.83{\times}10^{-3}mmol/mL{\cdot}min$ as a control. Reaction rate constant was a similar trend to initial reaction velocity.

• Journal of the Korean Geotechnical Society
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• v.38 no.4
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• pp.33-45
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• 2022

A series of model tests were performed in this study to demonstrate the clogging mechanism created during the installation of a compaction pile to improve soft ground. The application of an air-jet to extrude sand or aggregates from a casing during the installation of a compaction pile imposes a remarkably high-pressure difference between the composite soil layers of clay and sand (or aggregates), resulting in severe clogging. Therefore, a one-dimensional testing system was developed to simulate composite soil layers consisting of clay and sand (or aggregates) and to apply a high-pressure differential at both boundaries, thus replicating the extrusion process used in compaction pile installation. Herein, the performance of two construction materials for compaction piles of crushed stone and grading-controlled aggregates was compared. A series of one-dimensional model tests were performed under multiple pressure settings, with clogging depth and permeability measured in each case. Results indicate that, blinding clogging mechanisms and blocking defined by previous studies were observed for crushed stone, and a new mechanism of "infiltration" was revealed and defined. Whereas, the controlled aggregates performed excellently against clogging because only blinding was observed.

• Applied Biological Chemistry
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• v.29 no.4
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• pp.407-415
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• 1986

To obtain informations on the development of the combined granular pesticides for the simultaneous control of rice insect pests and diseases which often occur at the same time or in overlapping experiments were carried out on twelve mixture pesticides of granular type formulated by extrusion method with two fungicides and three insecticides. Each of 12 mixtures was tested for physico-chemical properties and efficacy against to rice leaf blast and brown planthoppers under the laboratory conditions. All of the mixture pesticides showed acceptable physico chemical properties as granular formulation. Most of the compounds in mixture pesticides showed a tendency to have lower stabilities than those of pesticide alone, therefore, it was necessary to add stabilizer in formulation process. Isoprothiolane combinations were found very effective against leaf blast but their control effects were similar to that of isoprothiolane alone due to its high efficacy, while probenazole-carbofuran combinations showed synergistic effects for the control of leaf blast. All of the combinations showed synergistic effects to brown planthoppers. But fenthion and 3% propoxur combinations resulted comparatively low efficacies. In the consideration of their physico-chemical properties and efficacies to rice pests, carbofuran and 6% propoxur combinations were promising combined granular pesticides for the simultaneous control of leaf blast and brown planthoppers, while fenthion and 3% propoxur combinations were not available because of their low efficacies for brown planthoppers.

• Korean Journal of Food Science and Technology
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• v.42 no.4
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• pp.494-501
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• 2010

The purpose of this study was to examine the presence of Bacillus cereus, aerobic bacteria and coliforms in the raw material of infant formulas and investigate the manufacturing process in terms of microbial safety. Among ten kinds of raw infant formula material samples (n=20), Bacillus cereus appeared in two (n=4). Aerobic bacteria were not detected in raw infant formula material or maximum 4.15 log CFU/g. Eleven species of aerobic bacteria were isolated and 76% of them were Sphingomonas paucimobilis, Pseudomonas fluorescens, Rhizobium radiobactor, or Stenotrophomonas maltophilia. A Pearson's correlation analysis revealed that the most influential factors for detecting Bacillus cereus were aerobic bacteria and coliforms. In other words, when the measured values of aerobic bacteria and coliforms were higher, the possibility that Bacillus cereus would appear increased. In a regression model to predict Bacillus cereus, the rate of appearance was correlated with aerobic bacteria and coliforms, and its contribution rate for effectiveness was 86%. Improving microbial quality control by pasteurization, spray dry, popping and extrusion resulted in a decrease in the numbers of Bacillus cereus, aerobic bacteria and coliforms in the raw materials. The results suggest that a hazard analysis and critical control point system might be effective for reducing microbiological contamination.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.4
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• pp.285-292
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• 2017

We investigated physicochemical properties of puffed snacks with intermediate and high amylose rice varieties. The intermediate amylose rice varieties 'Sindongjin' and high amylose rice varieties newly developed for food processing, 'Dodamssal' and 'Goami4' were tested for this study. The crude fat and crude protein contents of the rice cultivars ranged 1.47-3.08% and 6.30-7.63%, respectively. The resistant starch and amylose contents of Dodamssal and Goami4 were higher than those of Sindongjin. The hardness of rice was the highest in Sindongjin and Dodamssal. Also, Hardness of puffed snacks decreased by 72.07% for Sindongjin, 88.21% for Dodamssal and 66.67% for Goami4 compared to raw rice samples. The sensory evaluation showed that the highest scores in taste, texture and overall acceptability of puffed snacks were obtained in Dodamssal. The results of this study indicate that Dodamssal was suitable varieties for puffed snacks. Also, the physicochemical properties of Dodamssal were improved by the extrusion process. Therefore Dodamssal can be used for the industrial production of puffed snacks.