• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.11
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• pp.1327-1335
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• 2017

This study was carried out to determine the effect of cacao bean addition on the physicochemical properties of extruded rice flour. Rice-based cacao beans (0, 20, 40, 60%) were extruded at a die temperature of $130^{\circ}C$, screw speed of 200 rpm, and moisture content of 25%. As the content of cacao beans increased from 20% to 60%, expansion index decreased, while piece density and specific length increased. The water soluble index and water absorption index of the extrudate increased through extrusion cooking. Lightness decreased as cacao bean content increased while redness increased. As the content of cacao beans increased, paste viscosity decreased. Cold peak viscosity was observed in all extrudates of raw roasted cacao beans. ${\alpha},{\alpha}$-Diphenyl-${\beta}$-picrylhydrazyl (DPPH) radical-scavenging activity increased upon extrusion and cacao bean addition. As content of cacao beans increased, non-roasted cacao beans had higher total phenolic contents than roasted cacao beans. This study showed that addition of cacao beans to extruded rice snack improved antioxidant activity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.3
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• pp.427-433
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• 2013

This study was designed to examine changes in the physicochemical properties of extruded corn fibers with different amounts of feed moisture (30, 40, and 50%). The screw speed and die temperature were fixed to 200 rpm and $140^{\circ}C$, respectively. The crude ash, fat, and protein in corn fiber decreased from the extrusion process. The insoluble dietary fiber in corn fibers decreased, while soluble dietary fiber increased at a feed moisture of 30%. The specific length of the extruded corn fiber increased while the specific mechanical energy input, density, breaking strength, and elastic modulus decreased. The water absorption index (WAI) and reducing sugar content of the corn fibers did not significantly change, but the water soluble index (WSI) decreased as the feed moisture content of the corn fiber increased. On the other hand, the WAI of de-starched corn fiber decreased while WSI and reducing sugars increased as the feed moisture content of the corn fiber increased.

• Korean Journal of Metals and Materials
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• v.47 no.3
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• pp.175-181
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• 2009

Mechanical properties and precipitation behavior of backward extruded 6061 Al alloy for pressure vessel were investigated using tensile test, transmission electron microscopy (TEM) and differential scanning calorimeter (DSC). In this study, solution heat treatment (SHT) was performed at $535^{\circ}C$ for 30~90 min and aging treatment was conducted at 177 and $190^{\circ}C$ for 1~7 h. Maximum tensile strength of $36.6kgf/mm^2$ and yield strength of $33.29kgf/mm^2$ were achieved at the aging time of 5 h at $190^{\circ}C$. TEM observation showed that fine needle-like ${\beta}^{{\prime}{\prime}}$ phase which has 35~45 nm of length was uniformly distributed in the aged 6061 Al alloy specimen. From tensile test, TEM and DSC analysis, it is expected that aging time of 2~5 h at $190^{\circ}C$ is suitable for the extruded A6061 used as pressure vessels.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.5
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• pp.727-734
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• 1997

In practice, the design of forging processes is performed based on an experience-oriented technology, that is designer's experience and expensive trial and errors. Using the finite element simulation and the artificial neural network, we propose an optimal die geometry satisfying the design conditions of final product. A three-layer neural network is used and the back propagation algorithm is employed to train the network. An optimal die geometry that satisfied the same between inner extruded rib and outer extruded one is determined by applying the ability of function approximation of neural network. The neural networks may reduce the number of finite element simulation for determine the optimal die geometry of forging products and further they are usefully applied to physical modelling for the forging design.

• Journal of Korea Foundry Society
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• v.30 no.6
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• pp.210-216
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• 2010

The aim of this study is to characterize a thixoextruded 7075 Al wrought alloy bar in terms of its isotropic behavior through the optical microscope, mechanical test and electron back scattered diffraction. It is also discussed of the extrudability improvement for 7075 Al wrought alloy by thixoextrusion, with emphasis on controlling thixoextrusion parameters. Hot extrusion shows that the maximum extrusion pressure depends on their characteristics in terms of flow stress and hot workability. In the contrary, thixoextrusion demonstrates that the maximum extrusion pressure is almost uniform regardless of the experimental parameters, such as initial ram speed, die bearing length and thixoextrusion temperature. The hot extruded microstructures become elongated to extrusion direction, while the thixoextruded microstructures are isotropic and homogeneously distributed due to the existence of liquid phase between solid grains during the process. The grain refinement due to dynamic recrystallization during thixoextrusion has been also occurred. Subsequent recrystallization would lead to the strengthening of mechanical properties, as observed in the study. The important point is that the values of tensile, yield strength and elongation of the thixoextruded bar without plastic deformation are similar to those of the hot extruded bar with severe plastic deformation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.6
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• pp.751-758
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• 2017

The objective of this study was to determine the effects of moisture content and screw speed on the physical properties of extruded soy protein isolate (SPI). Expansion index, water absorption index, texture, integrity index, color, and nitrogen solubility index of extruded SPI were analyzed to determine the relationship with extrusion conditions. Extrusion conditions were moisture content (40, 50, and 60%) at a fixed die temperature ($140^{\circ}C$) and screw speed (250 rpm). The other extrusion conditions were screw speed (150, 250, and 330 rpm) at a fixed moisture content (55%) and die temperature ($140^{\circ}C$). Specific mechanical energy (SME) input decreased as moisture content increased from 40 to 60%. However, SME input increased as screw speed increased from 150 to 330 rpm. Expansion ratio and piece density decreased as moisture content and screw speed increased, and specific length increased as moisture content and screw speed increased. The extruded SPI at 40% moisture content had higher water absorption index, texture, and color differences than those of the extruded SPI at other moisture contents (50 and 60%). however, the extruded SPI at 40% moisture content had lower integrity index and cutting strength than those of the extruded SPI at other moisture contents (50 and 60%). In conclusion, the physical properties of extruded SPI were more affected by moisture content than screw speed.

• Transactions of Materials Processing
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• v.10 no.4
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• pp.311-318
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• 2001

Porthole die extrusion has a great advantage in the forming of long hollow section tubes. It is difficult to produce long hollow section tubes with complicated section by the conventional extrusion process with a mandrel on the stem Because of the limit of the length of mandrel and the complexity of cross section. Porthole die extrusion is affected by many parameters, such as extrusion ratio, extrusion speed, die geometry, porthole number, bearing length etc. Up to now, most of studies about porthole die extrusion have been investigated by experiments or steady state FE-analysis. However, in this paper, porthole die extrusion is analysed by the unsteady state 3D FE-simulation. And the result of unsteady state analysis is compared with the experimental result. Also, the surface state of extruded tubes are examined for the various process conditions.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.5
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• pp.73-81
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• 2003

In case of hollow cylinder extrusion using porthole die, the effects of extrusion parameters-temperature, the speed of extrusion, the shape of the die and mandrel-on metal flow in porthole die extrusion of aluminum have been investigated. However, there have been few studies about condenser tube extruded by porthole die. Original metal flow of condenser tube by porthole die extrusion is similar to hollow cylinder extrusion but the estimation of metal flow for extrusion parameters is different. For example, variation of chamber length in hollow extrusion only affects the welding pressure, however, the welding chamber length in condenser tube extrusion influences to the welding pressure as well as the deflection of mandrel. This study was designed to evaluate metal flow, welding pressure, extrusion load, tendency of mandrel deflection according to angular variation in the bottom of chamber in porthole die. Estimation was carried out using finite element method in as non-steady state. Analytical results can provide useful information the optimal design of porthole die.

• Science of Emotion and Sensibility
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• v.5 no.3
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• pp.53-59
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• 2002

The surface fibers on the fabric is one of decisive factors which affects human sensory evaluation as well as heat and moisture transfer characteristics. In this study the length and distribution of surface fibers that are extruded from the fabric surface of the wool/wool blend fabrics (14 wool fabrics and 10 wool blend fabrics) and its contribution to subjective sensory evaluation were investigated. In order to quantify the length and distribution of surface fibers, image analysis and wavelet transform technique were introduced. Instant warm-cool feeling of touch, Q$\_$max/, and contact area were also measured and related to the quantified surface fibers. To figure out the effect of surface characteristics on sensory evaluation, human sensory responses to three adjectives which represent surface characteristics and warm-cool feeling of touch were obtained and analyzed. The relationship between the quantified surface fibers assessed by wavelet energy and both warm-cool reeling of touch, Qmax, and human sensory response were discussed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.11a
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• pp.33-41
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• 2002

In case of hollow cylinder extrusion using porthole die, the effects of extrusion parameters-temperature, the speed of extrusion, the shape of the die and mandrel-on metal flow in porthole die extrusion of aluminum have been investigated. However, there have been few studies about condenser tube extruded by porthole die. This study was designed to evaluate metal flow, welding pressure, extrusion load, tendency of mandrel deflection according to variation of chamber length. in porthole die. Estimation was carried out using finite element method. Porthole die is analyzed in as non-steady state. Analytical results provide useful information the optimal design of porthole die.