• 한국자동차공학회논문집
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• 제8권3호
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• pp.56-64
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• 2000

A friction force measurement system using the floating liner method was developed to study the frictional behavior of piston rings. The measurement system was carefully designed to control the effect of the piston secondary motion and the temperature of cylinder wall and oil. The friction force between the barrel shaped piston ring and the cylinder liner, was measured under the condition of flooded oil supply. The measured friction forces were classified into five frictional modes with regard to the combination of predominant lubrication regimes(boundary, mixed and hydrodynamic lubrication) and stroke regions(midstroke and dead centers). The modes could be identified on the Stribeck diagram of the friction coefficients and the dimensionless number of ㎼/p, where the friction coefficients are evaluated at near the midstroke and dead centers.

• Preventive Nutrition and Food Science
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• 제13권4호
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• pp.299-305
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• 2008

This study compared the physicochemical properties of root hair of white ginseng (WG), root hair of tissue cultured mountain ginseng (MG), root hair of red ginseng (RG) and extruded ginseng samples. The comparison of crude ash and total sugar resulted insignificant differences between extruded and raw samples. MG had a higher content of crude ash, crude protein, amino acids and polyphenolic compound than WG and RG; the total sugar and reducing sugar were highest in RG. Crude fat and acidic polysaccharide in RG and WG were similar to and higher than MG. Crude saponin of treated samples WG1 (moisture content 25%, barrel temperature $110^{\circ}C$) and WG3 (moisture content 35%, barrel temperature $110^{\circ}C$) were 9.80% and 9.73%, respectively, which were the highest among ginseng samples. In conclusion, the extrusion process can be applied to red ginseng manufacturing, and some characteristics of MG were higher than in RG and WG.

• Journal of Magnetics
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• 제21권2호
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• pp.239-243
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• 2016

High temperature superconductor (HTS) magnet systems usually employ metal current leads which bridge between the cryogenic environment and room temperature. Such current leads are the dominant heat load for these magnet systems due to a combination of electrical resistance and heat conduction. HTS flux pumps enable large currents to be injected into a HTS magnet circuit without this heat load. We present results from an axial-type HTS mechanically rotating flux pump which employs a ferromagnetic circuit and a Cu-stabilized coated conductor (CC) HTS stator. We show the device can be described by a simple circuit model which was previously used to describe barrel-type flux pumps, where the model comprises an internal resistance due to dynamic resistance and a DC voltage source. Unlike previously reported devices, we show the internal resistance and DC voltage in the flux pump are not exactly proportional to frequency, and we ascribe this to the presence of eddy currents. We also show that this axial-type flux pump has superior current injection capability over barrel-type flux pumps which do not incorporate a magnetic circuit.

• Food Science and Biotechnology
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• 제17권6호
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• pp.1191-1196
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• 2008

The antibacterial and antioxidant potentials of extruded ginseng extract (EGE) with 60% ethanol and methanol were investigated. The inhibitory activity of the EGE in Gram-positive bacteria was significantly higher than in Gram-negative bacteria. Higher antibacterial activity was observed with methanol ginseng extract when moisture content and barrel temperature were 20% and $115^{\circ}C$, respectively, that diameter of inhibition zone at 1,500 mg/mL was $15.40{\pm}0.13\;mm$ for Bacillus subtilis and $9.31{\pm}0.05\;mm$ for Salmonella typhimurium. The amount of total phenolics was highest in extruded ginseng at 20% moisture content and $115^{\circ}C$ barrel temperature. Especially, a positive correlation was observed between the total phenolic content and antioxidant activity of the extracts. In the 2,2-diphenyl-1-picryhydrazyl radical (DPPH) system, all tested extract of extruded ginseng at 20% moisture content exhibited very strong antioxidant properties when compared to red ginseng with percent scavenging effect of 23-35% at 20mg/mL. In conclusion, it can be said that the extracts of extruded ginseng could be used as natural antimicrobial and antioxidant agents in the food preservation.

• 한국식품과학회지
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• 제29권1호
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• pp.65-71
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• 1997

압출성형공정에서 주로 자가발열로 전환되는 것으로 알려진 모터에너지를 자가발열 에너지와 기계에너지로 구분하였다. 온도 상승에 의한 에너지를 열에너지로 간주하였고, 모터에너지에서 자가발열로 전환된 에너지를 감한 나머지 에너지를 기계에너지로 정의하여, 일정한 배럴온도를 조건으로 할 때 열에너지 및 상대기계에너지(최저 스크류회전속도에서의 기계에너지를 0으로 기준하여 계산된 값)를 정량화할 수 있는 방법을 완성하였다. 콘그리트(corn grit)를 수분함량 $27{\sim}36%$의 범위에서 압출성형하였을 때, 스크류회전속도가 증가할수록 상대기계에너지는 크게 변화하였고, 열에너지는 거의 비슷하게 유지되었다. 수분함량이 높아질수록 상대기계에너지는 크게 증가하였고, 열에너지는 약간 증가하였다. 이로부터 수분함량이 높아질수록 모터에너지로부터 자가발열보다는 상대기계에너지의 작용이 커짐을 알 수 있었다.

• 한국기계가공학회지
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• 제17권3호
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• pp.148-154
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• 2018

When shooting small arms, the inner surface temperature is heated up to about $700{\sim}1,000^{\circ}C$ by the friction of the bullet and the inner wall of the barrel and the combustion of propellant. High-temperature propellant gas and high-speed movement of the bullet cause corrosion of the inner wall, which is noticeable immediately in front of the chamber. In this study, the mechanical properties of Cr-Mo-V steel, which is the base material, were tested using Taguchi experimental design to find the best nitriding treatment conditions. For the nitriding process, the working time, salt bath temperature, and salt concentration were combined as three conditions and placed in the $L_9(3^4)$, orthogonal array table. The thicknesses of the white layer and the nitrogen diffusion layer were measured after nitriding under each condition in a salt bath furnace. Durability was evaluated by measuring the degree of dispersion through actual shooting because it was difficult to evaluate the mechanical properties of the cylinder inner structure. As a result, it was confirmed that the durability was optimal at $565^{\circ}C$, 1 hour, 0.5%. These optimal conditions were selected by the statistical analysis of the Minitab program(ver.17).

• 한국식품영양과학회지
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• 제45권3호
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• pp.380-385
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• 2016

압출성형공정과 효소처리가 신령버섯 추출물의 ${\beta}$-glucan 함량에 미치는 영향을 조사하였다. 스크루 회전속도 250 rpm, 원료 사입량 100 g/min, 사출구 3 mm 원형으로 고정하였으며, 수분 함량 20, 30%, 배럴 온도 130, $140^{\circ}C$로 조절하여 압출성형 신령버섯을 제조하였다. 수분 함량 20%, 배럴 온도 $130^{\circ}C$의 압출성형공정을 통한 신령버섯 추출혼합물은 ${\beta}$-glucan 함량이 16.91 mg/g으로 다른 공정들보다 증가하였다. 수분 함량 20%, 배럴 온도 $130^{\circ}C$의 압출성형 공정과 Rohament CL로 처리한 추출물의 ${\beta}$-glucan 함량은 같은 압출성형공정의 Viscozyme L 처리 추출물 17.35 mg/g과 Plantase TL 처리 추출물 17.51 mg/g보다 18.32 mg/g으로 가장 많이 증가하였다. 결론적으로 압출성형공정과 Rohament CL 처리한 추출물의 ${\beta}$-glucan 함량이 18.32 mg/g으로 압출성형공정과 효소처리를 하지 않은 대조구의 14.45 mg/g보다 약 26.7% 정도 증가함을 나타내었다. 이는 신령버섯 추출 시에 압출성형공정과 효소처리가 ${\beta}$-glucan 함량을 대조구에 비해 증가시킬 수 있다고 판단되었다.

• 한국식품저장유통학회지
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• 제18권3호
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• pp.271-278
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• 2011

다습한 열대지방에서 카사바는 중요한 식물자원이다. 수분함량(20, 25%)와 배럴온도(110, $130^{\circ}C$) 에 따른 압출성형 카사바전분의 물리적 특성(밀도, 팽화율, 비기계적 에너지, 색, 수분용해지수, 수분흡착지수)와 호화특성을 조사하였다. 카사바전분 압출성형공정에서 수분 투입량은 압출성형물의 비기계적 에너지 투입량, 비길이, 밀도에 유의적으로 영향을 미쳤으며(p<0.05) 직경팽화지수, 겉보기탄성계수와 절단강도에서 유의성을 보여주었다(p<0.1). 또한 수분투입량과 배럴온도의 상호관계에서 비기계적 에너지 투입량과 밀도(p<0.1), 비길이(p<0.05), 적색도(p<0.01)는 유의성을 나타내었다. 수분투입량이 증가함에 따라 밀도, 겉보기탄성계수, 절단강도, 저온최고점도, 구조파괴점도, 최종점도는 증가하였으며, 직경팽화지수와 비길이는 감소하였다. 카사바전분 압출성형공정에서 수분투입량과 배럴온도는 명도와 황색도, 수분용해지수, 수분흡착지수에 영향을 미치지 않았다. 이 연구의 결과는 카사바 전분을 압출성형하여 사료와 식품을 개발하는데 유용하게 이용될 수 있을 것이다.

• 한국생산제조학회지
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• 제21권4호
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• pp.593-600
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• 2012

Thixomolding of Mg-alloy is a semi-solid injection molding process utilizing thixotropic phenomenon. Using this process, higher strength, thinner wall section and tighter tolerance without porosity are obtained. It has been applied for production of near-net-shape magnesium component. To design optimal thixomolding process of Mg-alloy part, molding conditions such as slurry temperature, mold temperature and injection time should be determined properly. Selection of these parameters has been dependent upon engineers' experience and intuitiveness. In this paper, to improve mechanical properties of the thixomolded product, optimal selection of process variables such as injection velocity, barrel temperature and die temperature in the process has been studied through microstructural analysis and Taguchi method. Performance of the process is verified through experiments.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.212-220
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• 2000

Single flighted screw extrusion is the most cost effective method for the production of film, sheet, pipe and the fundamental step in other processes including blow molding and injection molding. The temperature of polymer melts and injection pressure play a very important role in the injection molding machine. Thermal distortion and displacement of screw by temperature difference and injection pressure difference cause adhesive wear by metal-to-metal contact. In this paper we analyze thermal distortion and stress of screw includes pressure and temperature distributions by finite element analysis to understand dynamic characteristics of screw.