• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.1
• /
• pp.107-114
• /
• 2017

A turbocharger is an engine supercharger that is driven by exhaust gas. It improves the output and fuel efficiency by increasing the charging efficiency of the mixture gas, which is achieved by changing the rotatory power of the turbine connected to the exhaust passage. It is important to control the supercharging for this purpose. A nozzle slide joint is one of the core parts. Austenitic stainless steel is currently used as the material for this part, and its excellent mechanical properties include high heat resistance and corrosion resistance. However, because of its poor machinability, there are many difficulties in producing products with complicated shapes. Machining is used in the production of nozzle slide joints for high dimensional accuracy after metal powder injection molding. As design variables in this study, we investigated the sintering temperature, product stress, deformation rate, radius of curvature of the punch, and angle of the chamfer punch, which are related to the strain and shapes. The goal is to suggest a forming process using Nitronic 60 that does not require machining to manufacture a nozzle slide joint for a turbocharger. Accordingly, we determined the best process environment using finite-element analysis, the signal-noise ratio, and the Taguchi method for experiment design. The relative density and hydrostatic pressure of the final product were in accordance with the results of the finite element analysis. Therefore, we conclude that the Taguchi method can be applied to the design process of metal powder injection molding.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.46 no.4
• /
• pp.473-480
• /
• 2017

The aim of this study was to investigate the effects of gluten and moisture contents on the physical properties of extruded soy protein isolate. Extrusion conditions included various moisture (45, 50, and 55%) and gluten contents (20, 40, and 60%) at a fixed screw speed and die temperature of 250 rpm and $140^{\circ}C$, respectively. Specific mechanical energy input decreased as gluten content increased from 20 to 60%. Hydration ratio was highest ($293.23{\pm}13.68%$) at gluten and moisture contents of 20 and 55%, respectively. Lightness and yellowness increased as gluten content increased from 20 to 60% while redness decreased as gluten content increased. Color difference was the highest at low gluten and moisture contents. Integrity index was the highest ($71.15{\pm}0.93%$) at gluten and moisture contents of 60 and 45%, respectively. Nitrogen solubility index was not significantly affected by moisture content and was lowest ($22.46{\pm}1.11%$) at gluten and moisture contents of 60 and 55%, respectively. In conclusion, higher gluten and lower moisture contents were effective for texturization of soy protein isolate.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.46 no.4
• /
• pp.465-472
• /
• 2017

In this study, tuna sawdust was added to extruded meat analog in order to develop a meat analog with high quality. Addition of tuna sawdust has merit for utilizing a byproduct from poultry processing. Physicochemical characteristics were examined through the extrusion cooking process. The basic mixture of sample mixed with 65% deffated soy flour 25% isolated soy protein, and 10% corn starch was setup as the raw material. Three kinds of samples were made in total by addition of 15% and 30% tuna sawdust to this mixture. The extrusion process had a screw speed of 250 rpm, die temperature of $140^{\circ}C$, and moisture content of 50%. As addition of tuna sawdust increased, breaking strength and density decreased, specific length increased, and integrity and water holding capacity decreased. Likewise, nitrogen solubility index and protein digestibility decreased as addition of tuna sawdust increased. DPPH radical scavenging activity increased as addition of tuna sawdust addition, whereas it decreased as storage period increased to 30 or 60 days. The value of rancidity decreased as addition of tuna sawdust increased. However, 60 days later, radical scavenging activity increased more or less, and a significant difference was detected 150 days later. In conclusion, addition of tuna sawdust increased soft texture, and nutrition of the basic mixture sample. The process promoting functionality such as improvement of antioxidant function was confirmed through this study.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.33 no.2
• /
• pp.81-93
• /
• 2020

The fatigue characteristics of glass fiber reinforced plastic (GFRP) composites were studied under repeated loads using the finite element method (FEM). To realize the material characteristics of GFRP composites, Digimat, a mean-field homogenization tool, was employed. Additionally, the micro-structures and material models of GFRP composites were defined with it to predict the fatigue behavior of composites more realistically. Specifically, the fatigue characteristics of polybutylene terephthalate with short fiber fractions of 30wt% were investigated with respect to fiber orientation, stress ratio, and thickness. The injection analysis was conducted using Moldflow software to obtain the information on fiber orientations. It was mapped over FEM concerned with fatigue specimens. LS-DYNA, a typical finite element commercial software, was used in the coupled analysis of Digimat to calculate the stress amplitude of composites. FEMFAT software consisting of various numerical material models was used to predict the fatigue life. The results of coupled analysis of linear and nonlinear material models of Digimat were analyzed to identify the fatigue characteristics of GFRP composites using FEMFAT. Neuber's rule was applied to the linear material model to analyze the fatigue behavior in LCF regimen. Additionally, to evaluate the morphological and mechanical structure of GFRP composites, the coupled and fatigue analysis were conducted in terms of thickness.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.33 no.5
• /
• pp.899-904
• /
• 2004

The objectives of the experiment were to examine the effects of extrusion process variables on the yield of extruded ginseng extract and to determine the effect of ratio of extruded ginseng extract and microcrystalline cellulose on characteristics of spheronized granules by cold extrusion-spheronization process. Extrusion process variables observed were feed moisture (15, 22, 29%), die temperature (90 110 13$0^{\circ}C$) and screw speed (150 200, 250 rpm). The results showed that moisture content of dried ginseng significantly affected extraction yield (P<0.05). The less moisture content of the feed resulted in the higher yield of the extract. Moisture content of 15%, screw speed of 250 rpm and die temperature of 13$0^{\circ}C$ gave the highest yield of ginseng extract. Mean extraction yield of extruded ginseng using hot water extraction was greatly improved by extrusion process The extract yield of extruded ginseng was 43.5% which was higher than that of red ginseng (38.3%) and white ginseng (29.0%) produced by traditional process. It was possible to make from the mixture of microcrystalline cellulose (200 g) mixed with different concentration of 200 mL solution (0, 5, 20, 30 40 50 60% of ginseng extract with 59.2% dry solid) by using cold extrusion spheronization. When the concentration of ginseng extract Increased, the granulation yield was improved but friability and compression index were reduced. Ginseng extract such as saponin was completely released from spheronized granules in distilled water within 10 min. It can be concluded that spheroniged granule with ginseng extract could be packed in gelatin capsule since granules Possessed proper physical properties and quick release of saponin.

• Food Engineering Progress
• /
• v.21 no.2
• /
• pp.150-157
• /
• 2017

The objective of this study was to determine the effect of moisture contents (40, 50, 60%) and $CO_2$ gas injection (0 and 800 mL/min) on physicochemical properties of extruded soy protein isolate (SPI). The expansion ratio and the specific length increased, but piece density decreased with the increase in $CO_2$ gas injection from 0 to 800 mL/min at both 40 and 50% moisture contents. On the contrary, the expansion ratio and the specific length decreased, but piece density increased with the increase in $CO_2$ gas injection from 0 to 800 mL/min at 60% moisture content. Extruded SPI with $CO_2$ gas injection at 800 mL/min had small cell size and higher amount of cell than extruded SPI without $CO_2$ gas injection. The water holding capacity and nitrogen solubility index increased, and the integrity index and the texture decreased with the increase in $CO_2$ gas injection from 0 to 800 mL/min. In conclusion, extruded SPI with the $CO_2$ gas injection at 800 mL/min showed better expansion properties and cell formation than extruded SPI without the $CO_2$ gas injection.

• Food Engineering Progress
• /
• v.23 no.2
• /
• pp.118-124
• /
• 2019

This study aims to investigate the physical properties of extruded psyllium husk upon the addition of emulsifiers. Three different emulsifiers-glycerol monostearate (GMS), polyglycerol ester (PGE), and sugar ester (SE)-were added to the mixture of psyllium husk and rice powder before extrusion. Extrusion was performed using a twin-screw extruder at 140℃ die temperature, 200 rpm screw speed, and 16% feed moisture content. The physical properties of psyllium husk extrudates including expansion ratio, specific length, piece density, texture profile, color properties, water soluble index, and water absorption index were evaluated. It was observed that the expansion ratio was the highest while the specific length and piece density were the lowest in the control which had no emulsifiers. Texture profile analysis showed that the apparent elastic modulus and breaking strength were highest in the extrudate with a PGE of 0.1%. The adhesiveness was found to be lowest in the extrudates with an SE of 0.1% and GMS of 0.5%. Lightness value was highest in the extrudate with a PGE of 0.1%. Color difference, water soluble index, and water absorption index were highest in the control. The results reveal that some physical properties of extruded psyllium husk were improved with the addition of emulsifiers. This finding provides useful information for the development of psyllium snacks with good physical characteristics.

• Food Engineering Progress
• /
• v.23 no.4
• /
• pp.283-289
• /
• 2019

This study was performed to determine the effect of psyllium husk addition on the physical properties of rice extrudates. Rice-based formulations mixed with psyllium husk (0, 7, 14 and 21%) were extruded at a die temperature of 140℃, screw speed of 200 rpm, and moisture content of 20%. As the content of psyllium husk increased, expansion ratio decreased, while piece density and specific length increased. Apparent elastic modulus, breaking strength, adhesiveness, and hardness augmented with an elevation in psyllium husk content. Lightness declined as psyllium husk content furthered, while redness, yellowness, and color difference intensified. Water soluble index and water absorption index increased with an increased amount of psyllium husk. In conclusion, the addition of psyllium affected the expansion of extruded rice snack possessing hard texture, small cells, and sticky texture due to higher water absorption during hydration.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.29 no.1
• /
• pp.51-57
• /
• 2023

Because of the global pollution caused by plastic disposal, demand for eco-friendly transformation in the packaging industry is increased. As part of that, the utilization of polylactic acid (PLA) as a food packaging material is increased. However, it is necessary to improve the crystallinity of PLA by adding nucleating agents or to improve the modulus by adding fillers because of the excessive brittleness of the PLA matrix. Thus, the cellulose nanofiber (CNF) was fabricated and dried to obtain a powder form and applied to the CNF/PLA nanocomposite. The effect of CNF on the morphological, thermal, rheological, and dynamic mechanical properties of the composite was analyzed. We can confirm the impregnated CNF particle in the PLA matrix through the field emission scanning electron microscope (FE-SEM). Differential scanning calorimetry (DSC) analysis showed that the crystallinity of not annealed CNF/PLA nanocomposite was increased approximately 2 and 4 times in the 1st and 2nd cycle, respectively, with the shift to lower temperature of cold crystallization temperature (T_cc) in the 2nd cycle. Moreover, the crystallinity of annealed CNF/PLA nanocomposite increased by 13.4%, and shifted T_cc was confirmed.

• Composites Research
• /
• v.36 no.2
• /
• pp.126-131
• /
• 2023

Growing environmental concerns regarding pollution caused by conventional plastics have increased interest in biodegradable polymers as alternative materials. The purpose of this study is to develop a 100% biodegradable nanocomposite material by introducing organic nucleating agents into the biodegradable and thermoplastic resin, poly(lactic acid), to improve its properties. Accordingly, cellulose nanofibers, an eco-friendly material, were adopted as a substitute for inorganic nucleating agents. To achieve a uniform dispersion of cellulose nanofibers (CNFs) within PLA, the aqueous solution of nanofibers was lyophilized to maintain their fibrous shape. Then, they were subjected to primary mixing using a twin-screw extruder. Test specimens with double mixing were then produced by injection molding. Differential scanning calorimetry was employed to confirm the reinforced physical properties, and it was found that the addition of 1 wt% CNFs acted as a reinforcing material and nucleating agent, reducing the cold crystallization temperature by approximately 14℃ and increasing the degree of crystallization. This study provides an environmentally friendly alternative for developing plastic materials with enhanced properties, which can contribute to a sustainable future without consuming inorganic nucleating agents. It serves as a basis for developing 100% biodegradable green nanocomposites.