• 한국식품과학회지
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• 제22권1호
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• pp.105-109
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• 1990

Laboratary scale co-rotating twin-screw extruder(D=4mm, L/P=14)를 이용하여 쌀을 압출성형시켜 팽화 쌀 스넥으로 사용할 수 있는 extrudate를 제조하려고 시도하였다. 찹쌀가루를 원료로 하여 extrusion cooker의 screw speed를 200-360rpm으로 증가시키면, extrudate의 air cells 조직이 균일하게 개선되었으며, 원료의 수분함량은 적어도 17.5% 이하로 유지하는 것이 조직에 좋은 영향을 주었다. 찹쌀과 멥쌀의 powder와 grits를 원료로 사용했을 경우, extrudate의 객관적 및 관능적 텍스쳐는 powder가 grits보다 우수하였으며, 찹쌀과 멥쌀간의 차이는 현저하지 않았다. 그리고 extrudate를 기름에 튀기면 텍스쳐가 향상됨을 볼 수 있었다.

• 한국식품과학회지
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• 제28권1호
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• pp.169-178
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• 1996

밀기울의 압출가공시 스크류의 조합과 공정변수 조절에 따른 압출물의 특성을 나타내는 target parameters(수분용해지수, 압출물의 고유점도, 보수력과 보유력, 식이섬유, 압출물의 미세구조)의 변화를 연구하였다. 수분용해지수(WSI)는 원료의 수분함량에 가장 큰 영향을 받았고, 역방향 스크류(RSE)를 5개 사용한 경우 밀기울이 13.7%인 것에 비하여 압출물은 $16.3{\sim}23.2%$의 범위로 높은 WSI를 보였다. 밀기울 압출물의 고유점도는 RSE가 $3{\sim}5$개로 증가할수록 높아져 원료 밀기울이 10.6 ml/g인 것에 비하여 $37.86{\sim}45.44\;ml/g$의 수준으로 증가하였으며, 원료의 수분함량과 압출압력에도 큰 영향을 받았다. 고유점도(IV) X 수용성 고형분(SS)의 무차원 변수와 기계적 에너지 소모율(SME)과의 관계는 높은 상관관계$(R^2=0.85)$를 보여 밀기울 세포벽 수용화 반응에 SS와 분자량 크기의 상관관계가 SME에 의하여 지배받는 인자임이 확인되었다. 압출물의 보수력은 원료의 공급량과 수분함량이 높을수록 원료 밀기울보다 높은 값을 보였고, 보유력은 원료 밀기울에 비하여 낮았다. 압출물의 수용성 식이섬유는 원료의 수분함량이 적은 조건에서 $4.32{\sim}6.48%$의 분포를 보여 원료 밀기울 2.68%보다 크게 증가하였다. 이는 압출공정이 밀기울 세포벽의 수용화에 효과적으로 작용하였음을 의미한다. 압출물의 미세구조는 원료의 수분함량에 따라서 붕괴와 용융정도의 차이를 보여 주었다.

• Food Science and Biotechnology
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• 제14권1호
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• pp.28-31
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• 2005

To extract apple pectins, apple pomace (AP) was extruded under 14 different conditions of screw speed (250-350 rpm), feed rate of 30-40 kg/hr, and 20-30% moisture content using twin-screw extrusion. Response surface methodology (RSM), based on three variables by three-level factorial design, was employed to investigate effects of screw speed, feed rate, and moisture on dependent variables of extrudates, soluble dietary fiber (SDF), yield of anhydrogalacturonic acid ($Y_{AGA}$) representing pectin, and intrinsic viscosity ([${\eta}$]). Second order models were used to generate three-dimensional response surface for dependent variables, and their coefficients of determination ($R^2$) ranged from 0.96 to 0.99. Moisture content showed highest effect on solubilization of AP.

• Preventive Nutrition and Food Science
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• 제2권4호
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• pp.296-300
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• 1997

Glucose syrup and lactose, mixed with citric acid as a polymerizing catalyst, was processed using twin screw extruder, in which 40 of L/D(length/diameter) ratio was designed to provide sufficient retention in extruder for polymerization of sugars. The polymerization yields of glucose syrup were 36.90%, 55.44% and 77.10% at 160, 180 and 20$0^{\circ}C$, respectively, while those of lactose were 26.45%, 38.16% and 45.86% at the same temperatures. Gel permeation chromatography exhibited that the higher molecular weight fractions were increased with extrusion temperature, which also led to increasing hydrodynamic intrinsic viscosity. Both uco-oligosaccharides and lacto-oligosaccharides produced by extrusion of glucose syrup and lactose were stable for thermal treatments over a wide range of pH3.0~11.0. In addition, $\alpha$-amylase and amyloglucosidase treatment of gluco-oligosaccharides did not affect the solution viscosity, indicating the random linkage rather than $\alpha$-1, 4 linkages of glucose and thus the potential applications as a dietary fiber. In this research it was clearly observed that twin screw extrusion can be successfully utilized to produce gluco-oligosaccharides and lacto-oligosaccharides rapidly and continuously in conjunction with selective control of polymerized composition.

• 한국자동차공학회논문집
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• 제15권6호
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• pp.73-80
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• 2007

Nanocomposites are used as a new class of polymer system and many researchers have been interested in the clay nanocomposite because of its good mechanical properties, heat resistance, flame retardancy, and barrier property. Modified layered silicates as fillers are dispersed at a nanometer-level within a polymer matrix and then new extraordinary properties are observed. In this study, polypropylene/clay nanocomposites were prepared in a twin screw extruder by the melt compounding method. In order to increase the compatibility of PP with the clay, the MAPP was used as a compatibilizer. And organic modified clays were used as a nanometric filler during the melt extrusion. Through the analysis of SAXS, WAXS, the dispersion of clay was investigated. These nanocomposites compared with a neat polypropylene/talc composite have high modulus, low toughness, and reduced shrinkage at the stable dispersion.

• 한국전기전자재료학회논문지
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• 제22권11호
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• pp.935-940
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• 2009

In this research, the composites (100-x)LCP-xBNT (x = 0, 10, 20, 30, 40 vol.%) were fabricated with thermoplastic LCP(Liquid Crystal Polymer) and BNT($BaNd_2Ti_4O_{12}$) which is a high frequency dielectric material. Their dielectric properties, mechanical strength and microstructure were investigated by Impedance analyser, Instron and SEM. In order to fabricate LCP-BNT composites, LCP resin was put into the twin screw type mixer($310^{\circ}C$), melted by keeping for 10 min. After that, BNT filler was dispersed with melted LCP resin for 15 min. in the mixer. For measuring the dielectric properties and mechanical strength, Composite specimens were made by pressing composite granule (LCP-BNT) with 7 ton in the mold at $310^{\circ}C$. With increasing the BNT content (0~40 vol.%) of the composite, Its dielectric constant increased, dielectric loss and flexural strength decreased. The dielectric constant and flexural strength of composites with 20~30 vol.% of BNT filler are 4.1~6.0 and 35~55 MPa respectively. BNT/LCP composite is the potential substrate material for the high frequency application.

• Elastomers and Composites
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• 제40권3호
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• pp.159-165
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• 2005

반응성 모노머인 글리시딜메타크릴레이트 (GMA)를 과산화제를 이용하여 저밀도폴리에틸렌(LDPE)에 그라프트 한 후 이를 이용하여 나일론-6와 반응블렌드를 동방향 이축압출기를 사용하여 실시하였다. GMA의 그라프트는 FT-IR을 이용하여 확인하였으며, GMA의 그라프트율은 반응온도, 과산화제의 농도, 공단량체로 사용된 스티렌의 농도가 증가함에 따라 증가함을 알 수 있었다. LDPE/나일론-6 반응블렌드 보다는 LDPE-g-GMA/나일론-6 블렌드의 인장강도 및 신율이 향상됨을 알 수 있었으며, 스티렌이 첨가된 경우 보다 향상된 값을 나타냄을 알 수 있었다. 반응물의 모폴로지는 SEM을 이용하여 측정하였다.

• 한국해양공학회지
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• 제27권6호
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• pp.56-64
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• 2013

Crabbing motion is the pure sway motion of a ship without surge velocity. Thus, it can be applied to a berthing operation. Crabbing motion is induced by a peculiar operation method called the push-pull mode. The push-pull mode is induced by using a combination of the main propeller and side thruster. Two propellers generating the same amounts of thrust and rotating in opposite directions produce some yawing moment on a vessel but do not induce longitudinal motion. With the additional operation of side thrusters, the push-pull mode is used to induce a large amount of lateral force. In this paper, three-degree-of-freedom equations of motion such as for the surge, sway, and yaw are constructed for the crabbing motion. Based on these equations of motion, a feedback linearization control method is applied to auto-berthing control for a twin-screw ship with side thrusters. The controller can deal with the nonlinearity of a system, which is present in the berthing maneuver of a twin screw ship. A simulation of the auto-berthing of a ship is performed to validate the performance of the designed controller.

• 한국식품영양과학회지
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• 제43권9호
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• pp.1407-1414
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• 2014

쌀가루, 고아밀로오스 전분, 분리대두단백, 설탕 및 소금을 첨가하여 feed 수분함량 19~23%, screw speed 200~400 rpm, feed rate 43.6 kg/hr 조건에서 제조한 쌀 스낵의 이화학적 특성을 분석한 결과는 다음과 같다. 쌀 스낵의 bulk density는 0.06~0.21, apparent density는 0.55~0.65 정도로 나타났고, feed 수분함량이 많을수록, screw 속도가 감소할수록 증가하는 경향을 보였다. 쌀 스낵의 팽화율은 density와는 반대로 feed 수분함량이 낮을수록, screw 속도가 증가할수록 증가하였다. 쌀 스낵의 WAI는 feed 수분함량이 많을수록, screw 속도가 감소할수록 증가한 반면, WSI는 WAI와는 반대의 경향을 나타냈다. 쌀 스낵의 breaking strength는 feed 수분함량이 증가할수록, screw 속도가 감소할수록 증가하였다. 쌀 스낵의 색도 중 L값은 feed 수분함량 19%, 21%에서는 screw 속도가 증가할수록 L값은 낮았으나, feed 수분함량 23%에서는 screw 속도에 따른 유의적인 차이는 없었다. a, b값은 feed 수분함량 19%에서는 screw 속도가 증가함에 따라 높아졌다. 쌀 스낵의 x-ray 회절도는 feed 수분함량이 낮을수록, screw 속도가 높을수록 회절강도가 낮게 나타났고, feed 수분함량 19%, 21%, screw 속도 300 및 400 rpm에서는 V 도형의 특징을 나타냈다. 쌀 스낵의 내부 단면구조는 feed 수분함량이 많을수록, screw 속도가 낮을수록 기공의 생성이 잘 되지 않았고 세포벽이 두껍게 나타났다.

• Preventive Nutrition and Food Science
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• 제17권3호
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• pp.203-209
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• 2012

The effects of variable moisture content, screw speed and barrel temperature on the physicochemical properties of red ginseng powder extrudates were investigated. The raw red ginseng powders were processed in a co-rotating intermeshing twin-screw extruder. Primary extrusion variables were feed moisture content (20 and 30%), screw speed (200 and 250 rpm) and barrel temperature (115 and $130^{\circ}C$). Extruded red ginseng showed higher crude saponin contents (6.72~7.18%) than raw red ginseng (5.50%). Tested extrusion conditions did not significantly affect the crude saponin content of extrudates. Increased feed moisture content resulted in increased bulk density, specific length, water absorption index (WAI), breaking strength, elastic modulus and crude protein content and decreased water solubility index (WSI) and expansion (p<0.05). Increased barrel temperature resulted in increased total sugar content, but decreased reducing sugar content in the extrudate (p<0.05). Furthermore, increased barrel temperature resulted in increased amino acid content and specific length and decreased expansion and bulk density of extrudates only at a higher feed moisture content. The physicochemical properties of extrudates were mainly dependent on the feed moisture content and barrel temperature, whereas the screw speed showed a lesser effect. These results will be used to help define optimized process conditions for controlling and predicting qualities and characteristics of extruded red ginseng.