• Preventive Nutrition and Food Science
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• 제21권3호
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• pp.271-280
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• 2016

The effects of $CO_2$ injection and barrel temperatures on the physiochemical and antioxidant properties of extruded cereals (sorghum, barley, oats, and millet) were studied. Extrusion was carried out using a twin-screw extruder at different barrel temperatures (80, 110, and $140^{\circ}C$), $CO_2$ injection (0 and 500 mL/min), screw speed of 200 rpm, and moisture content of 25%. Extrusion significantly increased the total flavonoid content (TFC) of extruded oats, and ${\beta}$-glucan and protein digestibility (PD) of extruded barley and oats. In contrast, there were significant reductions in 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, PD of extruded sorghum and millet, as well as resistant starch (RS) of extruded sorghum and barley, and total phenolic content (TPC) of all extrudates, except extruded millet. At a barrel temperature of $140^{\circ}C$, TPC in extruded barley was significantly increased, and there was also an increase in DPPH and PD in extruded millet with or without $CO_2$ injection. In contrast, at a barrel temperature of $140^{\circ}C$, the TPC of extruded sorghum decreased, TFC of extruded oats decreased, and at a barrel temperature of $110^{\circ}C$, PD of extruded sorghum without $CO_2$ decreased. Some physical properties [expansion ratio (ER), specific length, piece density, color, and water absorption index] of the extrudates were significantly affected by the increase in barrel temperature. The $CO_2$ injection significantly affected some physical properties (ER, specific length, piece density, water solubility index, and water absorption index), TPC, DPPH, ${\beta}$-glucan, and PD. In conclusion, extruded barley and millet had higher potential for making value added cereal-based foods than the other cereals.

• 소성∙가공
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• 제31권3호
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• pp.117-123
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• 2022

In this study, a commercial AZ61 magnesium alloy is extruded at 300 ℃ and 400 ℃ and the microstructures, mechanical properties, and high-cycle fatigue properties of the extruded materials are investigated. Both extruded materials have a fully recrystallized microstructure with no Mg₁₇Al₁₂ precipitates. The average grain size and maximum basal texture intensity of the extruded material increase with increasing extrusion temperature. The material extruded at 400 ℃ (AZ61-400) has higher tensile yield strength and lower compressive yield strength than the material extruded at 300 ℃ (AZ61-300) because of the stronger basal texture of the former. Because of coarser grain size, the tensile elongation of AZ61-400 is lower than that of AZ61-300. Despite the differences in microstructures and tensile/compressive properties, the two extruded materials have the same fatigue strength of 110 MPa. This is because the finer grain size of AZ61-300 causes an increase in fatigue strength, but its weaker texture causes a decrease in fatigue strength. In both extruded materials, fatigue cracks initiate at the surface of fatigue specimens at all stress amplitudes tested.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 추계학술대회 논문집
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• pp.37-41
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• 2000

Extruded Profiles of Aluminum alloys have been widely used as parts and frames in mechanical and construction structures. Nowadays, mechanical processing of extruded Al alloy profiles is often employed for various industrial applications. Especially, the bending process is more and more applied and the process is greatly influenced by the distributed mechanical properties in the extruded profiles. Due to large reduction of area or extrusion ratio in ordinary production of extruded profiles, anisotropy is naturally induced by large severe deformation during the extrusion process. Therefore, the anisotropy properties play a great role in the bending process, as a post processing of extruded profiles and errors will be involved when the extruded profiles are treated as isotropic material, ignoring the induced anisotropy in the thin-walled extruded product. In the present work, the anisotropic material change is simulated, as a simplified method, employing Barlats six-component yield criterion in the rigid-plastic finite element method. Finite element computations are carried out for extrusion of a thin-walled part.

• 한국건축시공학회지
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• 제12권6호
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• pp.575-585
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• 2012

The extruded cement panel, which has many advantages as a prefabricated method, has been limited in its application due to its low fire-resistance. However, an extruded cement panel produced by mixing a-hemihydrate gypsum offers dramatically improved fire-resistance and is expected to have wide-ranging applications in the construction sector as an interior material or partition wall between housing units. Sound insulation performance is very important for the partition wall between housing units. In this study, the sound insulation performance of the extruded cement panel produced through the mixture of a-hemihydrate gypsum is reviewed in order to determine its usability for a partition wall between housing units and for interior materials. Through the review it was found that the wall formed using the extruded cement panels produced by mixing the a-hemihydrate gypsum have ★★★ class in sound insulation test, equal or superior compared with the other two types of extruded cement panel walls currently available in the market.

• 한국미생물·생명공학회지
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• 제19권5호
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• pp.514-520
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• 1991

Extrusion시켜 구조변형시킨 전분(질)을 기질로 cyclodextrin glucanotransferse(CGTase)를 활용하여 액화과정을 거치지 않고 직접 cyclodextrin을 합성하는 불용성 extrusion된 전분-수용성 CGTase로 구성된 불균일상 효소반응계에 관하여 연구하였다. Extrusion된 전분을 기질로 이용할 경우 기존의 액화전분을 기질로하는 균일상 효소반응계에서 보다 현저히 증가된 CD 농도, 수율 그리고 합성속도를 얻을 수 있었으며, extrusion된 전분 기질농도가 100g/l일 때 CD생성량과 수율은 각각 54g/l와 0.54였다.

• 한국분말재료학회지
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• 제2권1호
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• pp.44-52
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• 1995

Effects of the extrusion temperature and die angle on the tensile properties of SiCIyAl composites in powder extrusion have been investigated. SiCP/Al composites were extruded at various extrusion temperatures (450, 500, $550^{\circ}C$) under the extrusion ratio of 25 : 1. The ram speed was maintained at 13 cm/min for all the extrusion conditions. The surface of the extruded rod appeared to be smooth without tearing at 450 and 50$0^{\circ}C$, whereas it was very rough due to tearing at $550^{\circ}C$. It was found that the tensile strength and elongation of the composites extruded at $500^{\circ}C$ are greater than those of composites extruded at $450^{\circ}C$ This is due to the easier plastic deformation of composite extruded at $500^{\circ}C$, compared with the composites extruded at $450^{\circ}C$. The effect of die angle was examined under 20=60, 120, $180^{\circ}$die angles at extrusion temperature of $500^{\circ}C$ under 25:1 extrusion ratio. The tensile strength of the composites extruded with 20=$60^{\circ}$approved to be higher than that of the composties extruded with 28 : 120 and $180^{\circ}$This is attributable to the higher extrusion pressure, which mixed composite powders could be densely consolidated at elevated temperatures, resulting from high friction force between billet and sliding surface of conical die.

• 한국식품조리과학회지
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• 제28권6호
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• pp.813-820
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• 2012

To develop the high quality gluten-free rice products with health functionality and desirable texture with moistness, the physicochemical properties of extruded rice flours prepared from the mixture of germinated brown and white rices were investigated. The domestic organic Samgwangbyeo was used to make white and germinated brown rices. White rice (WR) was dried after soaked for 6 h at $15{\pm}3^{\circ}C$ and mixed with germinated brown rice (GBR) with different mixing ratios (100:0, 75:25, 50:50, 25:75, 0:100). The operating conditions of twin screw extruder were 250 rpm of screw speed, $120^{\circ}C$ of barrel temperature, and 25% moisture content of rice flour. The ash, crude protein and crude lipid contents were significantly different (p<0.05) and those of extruded GBR were the highest values, but those of extruded WR were the lowest. The color difference of extruded WR based on white plate showed the lowest among them. The water binding capacity (334.16%), swelling power (8.83 g/g), solubility (33.13%), and total starch (79.50%) were the lowest in extruded GBR. The viscosities of all extruded rice flours by RVA were maintained during heating. The peak and total setback viscosities of extruded rice flours ranged 127-352 and 58.0-85.5 cP, respectively. The novel food biomaterial from germinated brown rice as well as white rice was developed by twin screw extruder. The extruded rice flours control the moistness to improve the texture and also have functional materials, dietary fiber, GABA, and ferulic acid, etc to increase quality of gluten free rice products.

• 소성∙가공
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• 제31권5호
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• pp.253-260
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• 2022

In this study, the microstructural characteristics of a high-speed-extruded Mg-5Bi-3Al (BA53) alloy and its tensile, compressive, and high-cycle fatigue properties are investigated. The BA53 alloy is successfully extruded at a die-exit speed of 16.6 m/min without any hot cracking using a large-scale extruder for mass production. The homogenized BA53 billet has a large grain size of ~900 ㎛ and it contains fine and coarse Mg₃Bi₂ particles. The extruded BA53 alloy has a fully recrystallized microstructure with an average grain size of 33.8 ㎛ owing to the occurrence of complete dynamic recrystallization during high-speed extrusion. In addition, the extruded BA53 alloy contains numerous fine lath-type Mg₃Bi₂ particles, which are formed through static precipitation during air cooling after exiting the extrusion die. The extruded BA53 alloy has a high tensile yield strength of 175.1 MPa and ultimate tensile strength of 244.4 MPa, which are mainly attributed to the relative fine grain size and numerous fine particles. The compressive yield strength (93.4 MPa) of the extruded BA53 alloy is lower than its tensile yield strength, resulting in a tension-compression yield asymmetry of 0.53. High-cycle fatigue test results reveal that the extruded BA53 alloy has a fatigue strength of 110 MPa and fatigue cracks initiate at the surface of fatigue test specimens, indicating that the Mg₃Bi₂ particles do not act as fatigue crack initiation sites. Furthermore, the extruded BA53 alloy exhibits a higher fatigue ratio of 0.45 than other commercial extruded Mg-Al-Zn-based alloys.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.254-257
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• 1998

The twisting and the bending of extruded product are caused by the shapes of products and by the shapes of die surfaces and by the shapes of die land. Because the elliptical shape and the circular shape of the extruded product have the symmetry line of cross-section area, the twisting and the bending of product has not occurred. But the analysis by the DEFORM-3DTM show that the twisting and the bending of extruded product can be occurred by the twisting of the twisting of the die land and by the curving of the die land. The results by the analysis show that the twisting angle of the extruded procduct increases by the twisting angle of the die land and the curvature of the extruded products increases by the radius of bending of the die land.

• Journal of Biosystems Engineering
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• 제35권1호
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• pp.64-68
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• 2010

Cattle feedlot manure could be used effectively as the solid fuel for heating of agricultural facilities. Therefore, this study was carried out to investigate the thermal and physicochemical characteristics of solid fuel extruded with cattle feedlot manure. Calorific values of the solid fuel extruded with cattle feedlot manure, which was dried to the moisture contents of 0.0% (w.b) and 35.0% (w.b,) were 14,906 kJ/kg and 11,797 kJ/kg, respectively. Calorific value of extruded solid fuel was linearly decreased with the increase of moisture content. The first, second, and third reaction point during thermal pyrolysis of solid fuels extruded with cattle feedlot manure was investigated as $108.1^{\circ}C$, $312.2^{\circ}C$, and $459.4^{\circ}C$, respectively. The maximum reaction point was presented at the temperature of $312.2^{\circ}C$. Weight loss of extruded cattle feedlot manure during thermal pyrolysis until $600^{\circ}C$ was reached to about 60%. Volume decrease of initial extruded cattle feedlot manure was 61% during drying for the use as solid fuel. Maximum strength of extruded cattle feedlot manure, which was dried as the moisture content of 10% (w.b.) was 41,9150 N/$m^2$. Ignition gas analysis of extruded cattle feedlot manure presented that it has small amount of $NO_x$ and $SO_x$. It was shown that dried cattle feedlot manure had main components of C and O including small amount of Mg, Si, and Ca.