• Clean Technology
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• v.29 no.2
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• pp.126-134
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• 2023

Direct catalytic decomposition is a promising method for controlling the emission of nitrous oxide (N₂O) from the semiconductor and display industries. In this study, a γ-Al₂O₃ catalyst was developed to reduce N₂O emissions by a catalytic decomposition reaction. The γ-Al₂O₃ catalyst was prepared by an extrusion method using boehmite powder, and a N₂O decomposition test was performed using a catalyst reactor that was approximately 25.4 mm (1 in) in diameter packed with approximately 5 mm of catalysts. The N₂O decomposition tests were carried out with approximately 1% N₂O at 550 to 750 ℃, an ambient pressure, and a GHSV=1800-2000 h^-1. To confirm the N₂O decomposition properties and the effect of O₂ and steam on the N₂O decomposition, nitrogen, air, and air and steam were used as atmospheric gases. The catalytic decomposition tests showed that the 1% N₂O had almost completely disappeared at 700 ℃ in an N₂ atmosphere. However, air and steam decreased the conversion rate drastically. The long term stability test carried out under an N₂ atmosphere at 700 ℃ for 350 h showed that the N₂O conversion rate remained very stable, confirming no catalytic activity changes. From the results of the N₂O decomposition tests and long-term stability test, it is expected that the prepared γ-Al₂O₃ catalyst can be used to reduce N₂O emissions from several industries including the semiconductor, display, and nitric acid manufacturing industry.

• Food Science and Preservation
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• v.12 no.3
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• pp.241-246
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• 2005

This study showed the optimum conditions for producing rice extrudate added with the sea tangle powder, and presented the effects of moisture content, barrel temperature and the amount of sea tangle powder. From the results, the more the amount of sea tangle powder was added, the less the water absorption ratio was showed, while the more the texture became smooth, the more the expansion ratio increased. From the sensory evaluation, the best preference was obtained when the moisture content was $18\%$, and the barrel temperature was at $100^{\circ}C$. Between control and $10\%$ sea tangle, there was no significant difference in all observed parameters. But if more than $20\%$ sea tangle was added, low sensory evaluation scores were obtained due to the peculiar smell from sea tangle. From these results, addition of sea tangle below $10\%$(w/w) did not affect the quality of products.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.11
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• pp.1716-1723
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• 2014

This study was designed to examine the change in physical properties of extruded brown rice-vegetable mix at different pregelatinized brown rice contents and $CO_2$ gas injection. Moisture content, screw speed and die temperature were fixed to 30%, 100 rpm and 60, respectively. $CO_2$ gas injection was adjusted to 0, 300, 600, and 800 mL/min. The content of vegetables (carrot, pumpkin, kale and Angelica keiskei) mix was fixed 5%. Pregelatinized and raw brown rice powder were blended as the ratio of 0/95, 30/65 and 50/45. Specific mechanical energy input decreased as pregelatinized brown rice ratio increased. Expansion index increased and the size and number of pores increased but density decreased with the increasing in $CO_2$ gas injection. Gelatinization degree increased as $CO_2$ gas injection increased. In conclusion, cold extrusion with $CO_2$ gas injection at $60^{\circ}C$ die temperature could be applied for Saengsik (uncooked food) making.

• Applied Chemistry for Engineering
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• v.26 no.5
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• pp.615-620
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• 2015

Polypropylene (PP)/bamboo fiber (BF) composites were fabricated by twin screw extruder in order to investigate effects of the compatibilizer on physical properties of PP/BF composites. The content of BF changed from 10 to 25 wt% and that of the compatibilizer was fixed at 3 wt%. Maleic anhydride grafted PP (PP-g-MAH) was used to increase the compatibility between PP and BF as a compatibilizer. Chemical structures of the composites were confirmed by the existence of carbonyl group (C=O) stretching peak at $1,700cm^{-1}$ in FT-IR spectrum. Considering the degradation and mechanical properties, the optimum extrusion conditions were selected to be $210^{\circ}C$ and 100 rpm, respectively. There was no distinct changes in melting temperature of the composites, but the crystallization temperature increased by $10-20^{\circ}C$ owing to the heterogeneous nuclei of BF. It was checked that the optimum BF content was in the range of 15-20 wt% from the results of tensile and flexural properties of the composites. The effect of the compatibilizer on mechanical properties was confirmed by SEM images of fractured surface and contact angles.

• Journal of Powder Materials
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• v.9 no.6
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• pp.394-408
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• 2002

Nanostructured high strength metastable Al-, Mg- and Ti-based alloys containing different amorphous, quasicrystalline and nanocrystalline phases are synthesized by non-equilibrium processing techniques. Such alloys can be prepared by quenching from the melt or by powder metallurgy techniques. This paper focuses on one hand on mechanically alloyed and ball milled powders containing different volume fractions of amorphous or nano-(quasi)crystalline phases, consolidated bulk specimens and, on the other hand. on cast specimens containing different constituent phases with different length-scale. As one example. $Mg_{55}Y_{15}Cu_{30}$- based metallic glass matrix composites are produced by mechanical alloying of elemental powder mixtures containing up to 30 vol.% $Y_2O_3$ particles. The comparison with the particle-free metallic glass reveals that the nanosized second phase oxide particles do not significantly affect the glass-forming ability upon mechanical alloying despite some limited particle dissolution. A supercooled liquid region with an extension of about 50 K can be maintained in the presence of the oxides. The distinct viscosity decrease in the supercooled liquid regime allows to consolidate the powders into bulk samples by uniaxial hot pressing. The $Y_2O_3$ additions increase the mechanical strength of the composites compared to the $Mg_{55}Y_{15}Cu_{30}$ metallic glass. The second example deals with Al-Mn-Ce and Al-Cu-Fe composites with quasicrystalline particles as reinforcements, which are prepared by quenching from the melt and by powder metallurgy. $Al_{98-x}Mn_xCe_2$ (x =5,6,7) melt-spun ribbons containing a major quasicrystalline phase coexisting with an Al-matrix on a nanometer scale are pulverized by ball milling. The powders are consolidated by hot extrusion. Grain growth during consolidation causes the formation of a micrometer-scale microstructure. Mechanical alloying of $Al_{63}Cu_{25}Fe_{12}$ leads to single-phase quasicrystalline powders. which are blended with different volume fractions of pure Al-powder and hot extruded forming $Al_{100-x}$$(Al_{0.63}Cu_{0.25}Fe_{0.12})_x$ (x = 40,50,60,80) micrometer-scale composites. Compression test data reveal a high yield strength of ${\sigma}_y{\geq}$700 MPa and a ductility of ${\varepsilon}_{pl}{\geq}$5% for than the Al-Mn-Ce bulk samples. The strength level of the Al-Cu-Fe alloys is ${\sigma}_y{\leq}$550 MPa significantly lower. By the addition of different amounts of aluminum, the mechanical properties can be tuned to a wide range. Finally, a bulk metallic glass-forming Ti-Cu-Ni-Sn alloy with in situ formed composite microstructure prepared by both centrifugal and injection casting presents more than 6% plastic strain under compressive stress at room temperature. The in situ formed composite contains dendritic hcp Ti solid solution precipitates and a few $Ti_3Sn,\;{\beta}$-(Cu, Sn) grains dispersed in a glassy matrix. The composite micro- structure can avoid the development of the highly localized shear bands typical for the room temperature defor-mation of monolithic glasses. Instead, widely developed shear bands with evident protuberance are observed. resulting in significant yielding and homogeneous plastic deformation over the entire sample.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.5
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• pp.681-688
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• 1996

To investigate the effort of drying methods on the physicochemical properties of agar, gel strength, viscosity, melting and setting point, and phase transition by differential scanning calorimetery (DSC) during its heating were determined. In addition the structural differences of agar powder by scanning electron microscope (SEM) was examined. The most shortest onset temperature of gel strength increase was extruding method among any other methods. Viscosity of agar with hot air method, 400.00 cps at $45^{\circ}C$, was markedly increased, but with spraying and extruding ones were little change. The melting and setting point, and the temperature for maximum endothermic and enthalpy for agar with extruding one, $80.01^{\circ}C,\;36.05^{\circ}C\;and\;61.72^{\circ}C,\;0.73\;cal/g$, respectively, were lowest among the drying ones. But in the case of reheating after gelling, there were little change in all methods. Observing the surface structure of agar with SEM, extruding method showed the most unstable with absorptive property.

• Korean Journal of Food Science and Technology
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• v.27 no.2
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• pp.251-256
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• 1995

Sucrose is added to feed materials to alter the taste and texture of extruded products. Emulsifier can affect extrudate properties by forming complexes with amylose during extrusion-cooking. These ingredients may improve the cell structure and texture of cornmeal extrudates obtained by using $CO_{2}$ as a bubble forming agent. The objective of this study was to evaluate effects of sucrose (5% and 10%) and glyceryl monostearate (GMS) (0.75% and 1%) on properties of cornmeal extrudates produced with $CO_{2}$ at injection pressures from 1.04 to 2.07 MPa. Dough temperature increased and die pressure decreased when $CO_{2}$ was injected into barrel. The addition of sucrose to cornmeal resulted in decreasing dough temperature, specific mechanical energy (SME) input, and die pressure. SME input was not significantly influenced by GMS addition but die pressure was decreased when GMS was added. Extrudate density was decreased over observed $CO_{2}$ injection compared to GMS. WSI was significantly decreased with the addition of GMS. Paste viscosity was also decreased with addition of sucrose or GMS, but significant differences of paste viscosity among $CO_{2}$ injection pressures were not found. Stucture forming and texture of cornmeal extrudates by $CO_{2}$ injection was improved by adding GMS.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.2
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• pp.247-254
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• 2005

The objective of this study is to compare the chemical properties of red ginseng, white ginseng, and extruded ginseng. Six kinds of samples were prepared and examined their chemical components. The comparison among crude ash, crude lipid, and total sugar resulted insignificant difference. White ginseng had lower content of reducing sugar than those of extruded ginseng and red ginseng. Total amino acid was found relatively low in treatment A (sliced whole root and dried at 7$0^{\circ}C$). Total amino acid of treatment C (extruded dry whole root ginseng slices, moisture content 30%, barrel temperature 11$0^{\circ}C$, and screw speed 200 rpm) was higher than that of treatment B (extruded dry whole root slices, moisture content 25%, barrel temperature 11$0^{\circ}C$, and screw speed 200 rpm). Crude saponin of treatments A, B, C, D (white ginseng with skin), E (skinless white ginseng), and F (red ginseng) were 4.02, 4.77, 4.12, 3.56, 3.25, and 4.02%, respectively. Ginsenoside was contained similarly as crude saponin. The amount of ginsenoside in the treatment of A, B, C, D, E, and F was recorded respectively at 6.031, 8.108, 6.876, 7.978, 5.591, and 9.834 mg/g. A specific component in red ginseng, $R_{g3}$ was detected in treatment F. Maltol was detected in treatment Band F. Acidic polysaccharide was increased 2∼3% by extrusion process. In conclusion, extruded ginseng had similar components to those of red ginseng.

• Korean Journal of Food Science and Technology
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• v.34 no.3
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• pp.437-443
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• 2002

Using agar and gelatin as wall materials, onion oil was microencapsulated using the extrusion spraying technology. A sensitive methodology was developed for quantitative determination of the microencapsulation yield through ethyl acetate extraction and gas chromatographic analyses. Optimal conditions for the microencapsulation process consisting of the ratio of [core material, Cm] to [wall material, Wm] ($X_1$), temperature of dispersion fluid ($X_2$), detergent concentration in dispersion fluid ($X_3$), and concentration of emulsifier $(X_4)$ were determined using response surface methodology. The regression model equation for the yield of microencapsulation (Y, %) of onion oil could be predicted as $Y\;=\;97.028571-0.775000\;(X_1)-0.746726\;(X_1){\cdot}(X_1)\;-\;1.100000\;(X_3){\cdot}(X_2)$. The optimal conditions for the microencapsulation of the onion oil were determined as the ratio of [core material] to [wall material] of 4.5 : 5.5 (w/w), the temperature of dispersion fluid of $17.1^{\circ}C$ detergent concentration in dispersion fluid of 0.03%, and the concentration of emulsifier of 0.42%. Results revealed the most stable microcapsule of onion oil could be formed with the highest yield of microencapsulation (more than 95%) under optimal conditions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.9
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• pp.1211-1218
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• 2007

The aim of this study was to compare the fermentability and characteristics of fermented broths for white ginseng, red ginseng and extruded white ginseng at $110^{\circ}C$ (A), $120^{\circ}C$ (B) and $130^{\circ}C$ (C). The scanning electron microphotograph of B and C was uniform aircell distribution, but A had increased pore size and exploded some aircell's wall. Saccharification rate constant of C was the highest (10.123 $mg/mL·hr^{1/2}$). Fermentation temperature was $27^{\circ}C$ for 30 days and the cultivation was fixed with Saccharomyces cerevisiae, Aspergillus usamii, and Rhizopus japonicus. The pH of red ginseng fermented broth was 3.79, which was the highest among the fermented samples. The fermented broth of B had the highest acidity (4.46%). The fermented broth of A had the highest reducing sugar content in ginseng suspensions (32.36 mg/mL). In ginseng fermented broths, reducing sugar content was decreased rapidly during the initial 5 days and alcohol content was increased during the initial 5 days. On the fifth day, the fermented broth of C showed the highest alcohol content (5.20%).