• 동아시아식생활학회지
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• 제22권4호
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• pp.489-496
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• 2012

This research investigated the quality characteristics and anthocyanin content of wet noodles according to the amount of freeze-dried purple sweet potato powder. For viscosity, initial pasting temperature tended to increase compared to the control group, whereas peak viscosity, peak viscosity time and final viscosity steadily decreased. As the amount of purple sweet potato powder increased, breakdown value of viscosity and set back value significantly decreased. For chromaticity, as the amount of purple sweet potato powder increased, L-value decreased gradually, whereas a-value gradually increased and b-value significantly decreased compared to the control group. Anthocyanin content significantly increased in the addidtive group (91.79) compared to the control group (70.20). Measurement of texture characteristics found that hardness was highest in the control group, but it decreased as the amount of purple sweet potato powder increased. Springiness, gumminess and chewiness were highest in the control group. In the sensory evaluation, color, odor, chewiness, and overall acceptance were high in the 6% addictive group. In this study, by investigating the anthocyanin contents, quality characteristics and sensory attributes of wet noodles with freeze-dried purple sweet potato powder, we found that the 6% additive group is the best. Our results provide basic information for the development of noodles with purple sweet potato powder.

• E2M - 전기 전자와 첨단 소재
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• 제8권5호
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• pp.587-593
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• 1995

Silicone oils used insulating substances exhibit the both of organic and inorganic properties, and it has many superior characteristics such as the high thermal resistance and low thermal oxidation level when compared to other insulation oils. In order to investigate the dielectric loss due to the increase of viscosity, silicone oils of viscosity 1, 2, 5[cSt] had been chosen as the specimen and experiment has been performed in the temperature range of -70[.deg. C] - 65[.deg. C] and frequency range of 30 - 1*10$\^$5/[Hz]. As a result, the linear decrease of loss at low frequency region in high temperature was due to the influence of applying frequency, whereas the increase of loss at high frequency region was contributed by electrode's resistance. And increasing viscosity, the activation energy increased from 3.77[kcal/mole] to 7.21[kcal/mole]. The dipole moment of specimen was become clear 1.48 - 2.26[debyel in high temperature region(5 - 65[.deg. C]) and 1.05 - 1.80[debye] in low temperature region (-70 - -25[.deg. C])respectively.

• 한국기계가공학회지
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• 제3권2호
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• pp.67-72
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• 2004

Electro-Rheological(ER) fluids consist of suspensions of fine polarizable particles In a dielectric oil, which upon application of an external electric field control take on the characteristics of the Bingham solid. In this study, the temperature dependence of the viscosity was Investigated for an ER fluid consisting of 35 weight % of zeolite particles in hydraulic oil 46cSt. Thermal activation analysis was performed by changing the ER fluid's temperature from $-10^{\circ}C$ to $50^{\circ}C$. According to the analysis, the activation energy for flow of the ER fluid was 79.6 kJ/mole without applying electric field. On the other hand, with the electric field of 2kV/mm, the linearity between viscosity and temperature was not existed By changing the temperatures the viscosity (or shear stress) versus shear rates were measured. In this experiment shear rates were increased from 0 to $200s^{-1}$ in 2 minutes. Generally, the hydraulic oil 46cSt will be operated at the temperature of about $40^{\circ}C$, thus, the ER fluid's electric field dependence of viscosity was examined at this temperature. Also, an influence of adding the dispersant(Carbopl 940) on ER effect was discussed.

• Journal of Advanced Marine Engineering and Technology
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• 제15권1호
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• pp.59-70
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• 1991

Rupture of lubricant film, thermal characteristics, and variation of viscosity are very important factors to evaluate the performance of journal bearing. Variation of external conditions, load or rotational speed, largely influence these facters. For example, if rotational speed increases lubricant bulk temperature increases and viscosity drops. In this paper the effect of rotational speed variation on the characteristics of lubricant film in a journal bearing is investigated by experiment and theoretical analysis. It has been measured number of lubricant film rupture and lubricant bulk temperature form journal bearing which have been established at the various operating speed of shaft. The range of speed variation is from 900rpm to 2100rpm. Theoretical analysis has been carried out for rupture of lubricant film and thermal characteristics, and these results are compared with experimental results.

• 한국산학기술학회논문지
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• 제19권4호
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• pp.623-632
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• 2018

본 논문은 최적설계기법을 적용하여 Cross-WLF 모델의 계수 값을 효과적으로 추정하는 것이다. 사출성형 공정의 해석에서 주로 사용되는 Cross-WLF 점도 모델은 온도와 전단율의 영향이 민감한 고분자의 유변학적 특성을 잘 모사하는 모델로 널리 사용되고 있다. 정확한 폴리머 유변학적 특성 예측을 위해서는 정확한 Cross-WLF 계수 값의 추정은 필수이다. 실험적으로 획득한 데이터의 점도 값과 Cross-WLF의 계수 값을 설계변수로 가정하여 계산한 점도 값이 일치한다면, 최적화 기법을 통해 정의된 Cross-WLF모델이 실험 데이터를 정확하게 모사하는 것이라 할 수 있다. 이러한 Cross-WLF 모델을 통해 계산된 점도와 실험 데이터의 차이를 최소화하는 목적함수로 Cross-WLF의 계수 값을 설계변수로 정의하여 연구를 수행하였다. 본 논문에서 제시한 최적화기법의 타당성으로 확인하기 위하여 몇개의 소재를 대상으로 하여 Moldflow에서 제공하는 Cross-WLF 계수 값과 본 논문에서 제안한 방법으로 획득한 계수 값를 비교하여 잘 일치함을 확인하였다. 또한, Moldflow Plastic Lab의 실제 측정 데이터를 활용하여 추정한 결과 제안한 방법의 효율성 및 타당성을 입증하였다.

• 동아시아식생활학회지
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• 제22권6호
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• pp.795-801
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• 2012

This study was conducted to investigate the effects of loquat (Eriobotrya japonica Lindl.) leaf powder (LLP) on quality characteristics of dumpling shells. Dumpling shell samples were prepared with wheat flour containing different amounts of LLP, and their characteristics were then investigated. Amylography revealed that the gelatinization temperature of the LLP-wheat flours composite increased, while the initial viscosity at $95^{\circ}C$, viscosity at $95^{\circ}C$ after 15 minutes, and maximum viscosity, all decreased with increasing LLP content. As increasing amounts of LLP were added, the L and a values were reduced, whereas the b value was increased. Moreover, the addition of LLP increased hardness, cohesiveness, and adhesiveness, while it reduced springiness. Overall, sensory evaluation revealed that dumpling shells with 5% LLP were preferred more than other samples.

• Tribology and Lubricants
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• 제36권6호
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• pp.365-370
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• 2020

Recently, additive manufacturing (AM) technology has been applied to various industries such as automotive, aviation, medical, and electronics. Most prior studies are limited to the mechanical properties of printed materials, and few studies are being conducted on their tribological characteristics. However, the friction and wear characteristics of the material should be studied in order to utilize the components manufactured using AM technology as mechanical parts. In this study, the friction and wear characteristics of acrylonitrile-butadiene-styrene (ABS)-like resin printed with stereo lithography apparatus (SLA) 3D printing are evaluated according to the viscosity of silicon oil lubricant using a ball-on-disk experiment. Lubricants with a viscosity of 500, 1000, and 2000 cSt are prepared for the experiment. If silicon oil lubricants are used during the ball-on-disk test, the coefficient of friction (COF) and wear rates are significantly reduced, and the higher the viscosity of the lubricant, the lower will be the COF and wear rates. It is also verified that the temperature of the specimen owing to friction also decreases according to the viscosity of the lubricant. This is because of the silicon oil film thickness, and the higher the viscosity of the lubricant, the thicker will be the oil film. More studies on the tribological characteristics of 3D printing materials and suitable lubricants will be required to use 3D printed parts as mechanical elements.

• 대한기계학회논문집
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• 제14권5호
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• pp.1330-1336
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• 1990

The factors to act on atomization of liquid fuel are viscosity, geometric shape of nozzle, atomizing pressure, etc. Most of high viscous liquid fuels show decrease in viscosity by raising the preheat temperature, but the viscosity of liquid fuel like CWM does not readily change with fuel temperature. As an experimental study to investigate the atomizing characteristics of CWM, CWM fuel is atomizing with a twin-fluid atomizer, and the effects of the geometric shape of spray nozzle on atomization are investigated by measuring the Sauter`s Mean Diameter (SMD) of CWM. The summarized results obtained in this study are as follows ; (1) As the ratio of the mass flows of atomizing air to that of fuel (W$_{a}$ /W$_{1}$) increases, 능 decreases when fuel temperature is constant. (2) At the ratio (t/d) 4 of thickness (t) of spray nozzle hole to the diameter (d) of the hole, there is the best atomization. And SMD decreases when t/d is between 1 to 4 and increases when t/d > 4.

• 동아시아식생활학회지
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• 제14권2호
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• pp.145-155
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• 2004

From the cooking data, Japanese rice showed higher water uptake but lower expansion volume, pH and iodine blue value than those of Korean rice. Japanese rice had higher maximum viscosity, breakdown viscosity and pasting temperature but lower final viscosity and setback viscosity than those of Korean rice by RVA analysis. Japanese rice had higher LC (low compression) hardness, U stickiness and HC (high compression) stickiness, LC balance and HC balance, but had lower HC hardness and thickness in the tensipresser data. Also Japanese rice had higher stickiness and balance, and lower hardness from the texturometer analysis. Japanese rice showed higher a cooked taste score than that of the Satake cooked taste machine. The various mean values of Japanese rice after cooking showed better cooking characteristics than the Korean rice. These results might be caused because Japanese rice had a little lower amylose and protein content, but higher tat acidity content.

• 복식문화연구
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• 제5권3호
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• pp.151-158
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• 1997

This study was to find out the differences of the characteristics on chitosan from source, the crab and the shrimp. Chitosan was depolymerized in NaBO₃·4H₂O under various reaction time and temperature. 4 Chosen chitosan dissolved in acetic acid and treated to cotton fabrics. The cotton fabrics treated with chitosan showed an exellent antibacterial activity irrespective of the viscosity. Stiffness of the treated cotton fabrics increased 3∼8 times than untreated cotton fabric, it gives harshness to treated cotton fabrics, it gives harshness to treated cotton fabrics like linen. Air permeability of the treated cotton fabrics increased. Stiffness and air permeability are respective to viscosity of the chitosan.