• KSBB Journal
• /
• v.27 no.3
• /
• pp.137-144
• /
• 2012

Among various pretreatment processes for bioethanol production, extrusion pretreatment, one of cheap and simple process was investigated to efficiently produce fermentable sugars from micro alga, Chlorella sp. The biomass was pretreated in a single screw extruder at five different barrel temperatures of 45, 50, 55, 60 and $65^{\circ}C$, respectively with five screw rotation speed of 10, 50, 100, 150 and 200 rpm. The pretreated biomass was reacted with two different hydrolyzing enzymes of cellulase and amyloglucosidase since the biomass contained different types of carbohydrates, compared to cellulose of agricultural by-products such wheat and corn stovers, etc. In general, higher glucose conversion yield was obtained as 13.24 (%, w/w) at $55^{\circ}C$ of barrel temperature and 100 rpm of screw speed conditions. In treating 5 FPU/glucan of cellulase and 150 Unit/mL of amyloglucosidase, ca. 64% of cellulose and 40% of polysaccharides in the micro alga were converted into glucose, which was higher yields than those from other reported data without applying an extrusion process. 84% of the fermentable sugars obtained from the hyrolyzing processes were fermented into ethanol in considering 50% of theoretical maximum fermentation yield of the yeast. These results implied that high speed extrusion could be suitable as a pretreatment process for the production of bioethanol from Chlorella sp.

• Korea-Australia Rheology Journal
• /
• v.20 no.4
• /
• pp.235-243
• /
• 2008

The aim of this study is to explore the possibility of incorporating supercritical carbon dioxide ($scCO_2$) into twin screw extrusion process for the production of polypropylene-clay nanocomposite (PPCN). The $CO_2$ is used as a reversible plasticizer which is expected to rapidly transport polymeric chains into the galleries of clay layers in its supercritical condition inside the extruder barrel and to expand the gallery spacings in its sub-critical state upon emerging from die. The structure and properties of the resulting PPCNs are characterized using wide-angle X-ray diffraction (WAXD), transmission electron microscopy (TEM), rheometry, thermogravimetry and mechanical testing. In the processing of the PPCNs with $scCO_2$, optimum $scCO_2$ concentration and screw speed which maximized the degree of intercalation of clay layers were observed. The WAXD result reveals that the PP/PP-g-MA/clay system treated with $scCO_2$ has more exfoliated structure than that without $scCO_2$ treatment, which is supported by TEM result. $scCO_2$ processing enhanced the thermal stability of PPCN hybrids. From the measurement of linear viscoelastic property, a solid-like behavior at low frequency was observed for the PPCNs with high concentration of PP-g-MA. The use of $scCO_2$ generally increased Young's modulus and tensile strength of PPCN hybrids.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.22 no.1
• /
• pp.145-149
• /
• 2013

The performance of injection molding machine's control system, such as reproducibility, repeatability, etc, is widely studied nowadays. Since screw stroke, injection cylinder body pressure and barrel temperature are the most important terms of injection unit, interval linearity and repeatability to each parameter are analyzed here. Barrel temperature is analyzed according to the repeatability of the thermocouple at $150^{\circ}C$, $210^{\circ}C$, $300^{\circ}C$ using a precise oven. The result temperature is within ${\pm}0.5^{\circ}C$ Through the reliability evaluation of the most important terms of injection unit, the method of evaluating the linearity and repeatability is proposed and verified.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.1
• /
• pp.12-18
• /
• 2009

In this paper, for reducing the assembly torque of subminiature plastic barrel and base which are the essential parts of mobile phone camera module, the high-precision system for inspecting the screw shape of core, electrode and injection molding products was developed. For realization of inspection process, the inspection parameters for evaluating the manufacturing quality were selected and the measurement methods of selected parameters were developed. Finally, the inspection system which is possible to be applied to the field were fabricated.

• Hip & pelvis
• /
• v.30 no.4
• /
• pp.269-275
• /
• 2018

Purpose: The purpose of this study is to describe a method of inserting cement in the femoral head before fixation with dynamic hip screw to prevent screw cut out due to osteoporosis and to evaluate its clinical outcome in these patients. Materials and Methods: In this prospective study, 30 patients aged 60 years and older with intertrochanteric fracture were included. Bone mineral density was measured. After reaming of the femoral head and neck with a triple reamer and polymethyl methacrylate, bone cement was introduced into the femoral head using a customized nozzle and a barrel fitted on a cement gun. A Richard screw was inserted and the plate was fixed over the femoral shaft. Patients were mobilized and clinical outcomes were rated using the Salvati and Wilson's scoring system. Results: More patients included in this study were between 66 and 70 years old than any other age group. The most common fracture according to the Orthopaedic Trauma Association classification was type 31A2.2 (46.7%). The T-score was found to be $-2.506{\pm}0.22$ (mean${\pm}$standard deviation); all patients were within the range of -2.0 to -2.8. The duration of radiological union was $13.67{\pm}1.77$ weeks. Salvati and Wilson's scoring at 12 months of follow up was $30.96{\pm}4.97$. The majority of patients were able to perform their normal routine activities; none experienced implant failure or screw cut out. Conclusion: Bone cement augmentation may effectively prevent osteoporosis-related hardware complications like screw cut out in elderly patients experiencing intertrochanteric fractures.

• Journal of Fisheries and Marine Sciences Education
• /
• v.27 no.5
• /
• pp.1352-1363
• /
• 2015

This study was carried out to investigate the characteristics of the dependent variables depending on the condition changes of independent variable of the operation and the material during the production of collets added with rice and dried shrimp by using single extruder to utilize as basic data for the manufacture of extrusion collets. A total of 7 independent variables were set up as a raw, 20, 40 and 60 mesh for the powder particle size of rice; 12, 14, 16 and 18% for the moisture content of rice; 2, 4, 6 and 8% for the addition amount of dried shrimp; 90, 95, 100 and $110^{\circ}C$ for the barrel temperature; 210, 280 and 340 rpm for the screw speed; 4, 6, 8 and 10 mm for the discharge port diameter; 30, 40, 50 and 60 kg/h for the input amount of the mixed material. The characteristics of the dependent variables including puffing ratio, moisture content, lightness, uniformity, productivity of collets was to be studied by changing the conditions of the independent variables. As a results of this study, 20 mesh of powder particle size of rice, 14% of moisture content of rice, 4% of addition amount of dried shrimp, $100^{\circ}C$ of barrel temperature, 280 rpm of screw speed, 6 mm of discharge port diameter and 50 kg/h of input amount of mixed material were found to be the most preferable over other independent variables for the production of extrusion collets. In conclusion, it is necessary to set the independent variable in order to produce the high quality collets added with the rice as the main raw material and dried shrimp as the sub-materials.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1668-1671
• /
• 2005

Vulcanized natural rubber was pulverized using a single screw extruder in a non-cryogenic Solid Shear Extrusion process where rubber granulates were subjected to high compressive and shear stresses. The producted particles had diameters ranging from 40 to 1200$\{mu}m$. A principle used in this paper was developed in Russia. The development method for producing a polymeric material powder consists in compressing said material by shearing the material during a pressure increase and cooling. Consecutive breakdown is carried out by shearing the material during the pressure decrease and cooling.

• Food Science and Biotechnology
• /
• v.14 no.6
• /
• pp.758-765
• /
• 2005

Instant powders that only require mixing with water prior to consumption can be produced by extrusion for use in products such as instant beverages. Both extrusion processing conditions and particle size of powder are important to end-product characteristics. In this study, a twin-screw extruder was used under various processing conditions (feed moisture, barrel temperature, and screw speed) to produce extrudates from soft wheat flour, which were ground to powders with particle size ranges of less than 93, 93-145, and $145-249\;{\mu}m$. Effects of adding soy lecithin to wheat flour before extrusion were also investigated. Water absorption, solubility, suspension viscosity, and dispersibility of wheat powders were related to specific. mechanical energy measured during extrusion. Powder particle size was important to instant properties, especially ease of dispersal in water and stability to sedimentation. Addition of lecithin significantly improved dispersibility of powders.

• Food Science and Biotechnology
• /
• v.16 no.3
• /
• pp.381-385
• /
• 2007

The objective of this experiment was to study the influence of feed moisture content on the degree of enzymatic hydrolysis of com starch in a twin screw extruder and the saccharification yield of the dried extrudate. The feed moisture content was set at 25, 30, and 35% and ${\alpha}$-amylase solution was directly injected into the feed section at a barrel temperature of $95^{\circ}C$ and screw speed of 250 rpm. Amyloglucosidase was used for the saccharification of the dried extrudate at a concentration of 0.055%(w/w). Expansion ratio and swelling factor of extrudates decreased with increasing the feed moisture content. Addition of ${\alpha}$-amylase during extrusion process raised reducing sugar content of extrudates which also increased with the feed moisture content. The saccharification yield of dried extrudate was higher for the extrudate with lower feed moisture content.

• Preventive Nutrition and Food Science
• /
• v.11 no.4
• /
• pp.318-322
• /
• 2006

The objective of this experiment was to investigate the effect of extrusion of ginseng roots in twin screw extruder on susceptibility of ginseng starch toward hydrolysis by ${\alpha}-amylase$ BAN 480L (Novozyme, Denmark) and cellulase Celluclast 150L and saccharification by amyloglucosidase AMG-E (Novozyme, Denmark). The extrusion was conducted at 22% and 30% moisture contents of feed at screw speed 300 rpm. Barrel temperature at zone 1 was adjusted at $100^{\circ}C$ and $120^{\circ}C$. The results showed that extrusion process improved the ginseng ${\alpha}-amylase$ susceptibility as compared to traditionally dried ginseng (white and red ginseng). Reducing sugar of hydrolyzed extruded samples was 2,500% of its initial concentration, whereas the reducing sugar of hydrolyzed non-extruded sample was only 200% of its initial concentration. However, addition of cellulase during liquefaction lowered the saccharification yield of both non-extruded and extruded samples as well.