• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.6
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• pp.81-86
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• 2007

Biodiesel fuel that consists of saturated and unsaturated long-chain fatty acid alkyl esters is an alternative diesel fuel produced from vegetable oils or animal fats. However, air causes autoxidation of biodiesel fuel during storage, which can reduce fuel quality by adversely affecting its properties, such as the kinematic viscosity and acid value. One approach for improving the resistance of fatty derivatives to autoxidation is to mix them with antioxidants. This study investigated the effectiveness of five such antioxidants in mixtures with biodiesel fuels produced by three biodiesel manufacturers : tert-butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PrG) and $\alpha$-tocopherol. Oxidation stability was determined using Rancimat equipment. The results show that TBHQ, BHA, and BHT were the most effective and $\alpha$-tocopherol was the least effective at increasing the oxidation stability of biodiesel. This study recommends that TBHQ and PrG be used for safeguarding biodiesel fuel from the effects of autoxidation during storage.

• Journal of Mechanical Science and Technology
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• v.17 no.10
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• pp.1583-1596
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• 2003

A study of forced convection in a circular pipe with a partially filled porous medium was numerically investigated. The Brinkman-Forchheimer extension of the Darcy model was used to analyze the and temperature distribution in the porous medium. Our study includes two types of porous layer configurations: (1) a layer attached at the tube wall extending inward towards the centerline and (2) a layer at the centerline extending outward. The effect of several parameters, such as Darcy number, effective viscosity, effective thermal conductivity, and inertia parameter, as well as the effect of geometric parameters, were investigated.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.280-283
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• 2002

In the manufacturing of large scale composite structures, the cost-effective processing and the enhancement of structural performance are critical. One of the most effective ways for this purpose is to use stitched multiaxial warp knitted (MWK) perform in the resin transfer molding process. This study reports the effect of stitching on the mechanical properties of MWK composites, and the feasibility processing of the thick U-beam structure utilizing the stitched preforms. Permeability of the preform, viscosity and cure property of the epoxy resin have been measured. The results of resin flow analysis has been used in determining the gate/vent locations of the RTM mold. Cross-sectional observation of the channel beam prototype demonstrated that the resin impregnation was almost complete, except for some surrounding area of stitched yarns.

• Korea-Australia Rheology Journal
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• v.14 no.3
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• pp.121-128
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• 2002

A series of thermoplastic polymers and their blends were melt-processed with high intensity ultrasonic wave in an intensive mixer. For the effective transfer of ultrasonic energy, an experimental apparatus was specially designed so that polymer melt can directly contact with ultrasonic horn. It was observed that significant variations in the rheological properties of polymers occur due to the unique action of ultrasonic wave without any aid of chemical additives. It was also found that the direct sonication on immiscible polymer blends in melt state reduces the domain sizes considerably and stabilizes the phase morphology of the blends. The degree of compatibilization was strongly affected by viscosity ratio of the components and the morphology was stable after annealing in properly compatibilized blends. It is suggested that ultrasound assisted melt mixing can lead to in-situ copolymer formation between the components and consequently provide an effective route to compatibilize immiscible polymer blends.

• Journal of Power System Engineering
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• v.1 no.1
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• pp.98-105
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• 1997

In general, crankshafts which are used in internal combustion reciprocating engines are subjects to high torsional vibration. Therefore, a damper is often used to minimize the torsional vibration in reciprocating engines. In this paper, in order to investigate damping performance of viscous damper, the real effective viscosity and complex damping coefficient of silicone oil, and the effective inertia moment of inertia ring are calculated considering the relative motion between damper casing and inertia ring. Based on these results multi-cylinder shaft is modeled into equivalent 2-degree of freedom system and optimum condition is estimated by calculating the amplification factor of viscous damper. Also the test damper was manufactured according to the result of theoretical investigation, the performance and durability was ascertained through experimental examination.

• Journal of Dairy Science and Biotechnology
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• v.23 no.1
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• pp.27-37
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• 2005

The development of functional foods started booming from several years ago in the world. The size of functional materials are in the range of micrometer level. This size can be much smaller into nanometer level to be more effective. We face some problems from the materials, such as flavor, taste, color, viscosity, etc. in functional materials. The problems can be solved by micro / nanoencapsulation technique. This paper showed some results of the research related on the technique for functional milks and dairy products. The nono / microcapsules are the form of liquid instead of solid. Coating materials used were fatty acid esters, and core materials were lactase, iron, ascorbic acid. isoflavone, and chitooligosaccharide. The ranges of capsules are from 100 nm to 200 ${\mu}$m. The sample milks added nano/microcapsules were homogeneous and prevented the defects of core materials. It was observed that nano / microcapsules in milk and dairy products were effective as functional material without defaults. It was indicated that targeted functional foods can be developed further in various foods by nanotechnology.

• Journal of Electrochemical Science and Technology
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• v.8 no.1
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• pp.1-6
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• 2017

The conductivity of the electrolyte used plays a critical role in the optimization of the performance of electrochemical double layer capacitors. However, when the difference in the conductivities of different electrolytes is not significant (only 10-20%), the conductivity has little effect on the capacitance. On the other, unlike the conductivity and viscosity of the electrolyte, the cation size directly influences the capacitance. Cyclic ions have a smaller effective radius than that of the corresponding acyclic ions because the acyclic alkyl groups have a greater number of conformational degrees of freedom, such as the rotational, bending, and stretching modes. Consequently, because of the smaller effective size of the cyclic ions, cells containing electrolytes with such ions exhibit higher capacitances than do those with their acyclic counterparts.

• Applied Biological Chemistry
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• v.31 no.1
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• pp.65-78
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• 1988

This study aims effective use of soymilk residue, by-product of soymilk production, and making noodles by mixing soymilk residue with wheat flour. The results of viscosity property, cooking test of dry noodles, texture test of cooked noodles, and sensory test of cooked noodles were as follows. The color of cooked noodles were slightly shifted to yellowness according to the mixing of soymilk residue. The mixing of soymilk residue resulted in the decrease of texture and the loss of solids due to the decrease of visccelasity. Na-alginate, Na-C.M.C., guar gum, and crude gluten were added to improve the texture of noodles mixed with soymilk residue. As the results, either Na-alginate or guar gum was very effective in increasing the viscosity of composite flour and either guar gum or crude gluten was very effective in improving cooking quality. The texture of noodles supplemented by Na-alginate 1.0%, Na-C.M.C. 2.0%, guar gum 0.5%, or crude gluten 2.0% was similar to that of wheat flour noodles. Complex additives mixed with two different additives were very effective in improving noodle-making characteristics. Especially, the properties of the soymilk residue mixed noodles supplemented by crude gluten 1.0% and Na-C.M.C. 1.0% or crude gluten 1.0% and gum 0.5% were nearly the same in the texture organoleptic properties compared with those of wheat flour noodles.

• KSBB Journal
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• v.13 no.2
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• pp.209-213
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• 1998

The characteristics of de-emulsification of pertroleum emulsion by Nocardia amarae were investigated. Insoluble medium containing n-hexadecane was more effective than soluble medium in de-emulsification of emulsion containing diesel and bunker C as the organic phase. Emulsion made by the addition of xanthan or bioemulsifier was de-emulsified by N. amarae, and longer culture age was effective. In low viscosity range, organic phase with longer carbon chain was more effective. The contact, angle between bacterial film and water droplet in air increased from 16 degree for 4 day culture age to 26 degree for 15 day. The contact angle between bacterial film and water droplet in kerosene, n-heyxane or n-hexadecane also increased to greater than 100 degree after 3 day culture age. The hydrophobicity of bactgerial film increased according to the culture age.

• Geomechanics and Engineering
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• v.23 no.2
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• pp.151-163
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• 2020

Grouting method is an effective way of reinforcing cracked rock masses and plugging water gushing. Current grouting diffusion models are generally developed for horizontal cracks, which is contradictory to the fact that the crack generally occurs in rock masses with irregular spatial distribution characteristics in real underground environments. To solve this problem, this study selected a cement-sodium silicate slurry (C-S slurry) generally used in engineering as a fast-curing grouting material and regarded the C-S slurry as a Bingham fluid with time-varying viscosity for analysis. Based on the theory of fluid mechanics, and by simultaneously considering the deadweight of slurry and characteristics of non-uniform spatial distribution of viscosity of fast-curing grouts, a theoretical model of slurry diffusion in an oblique crack in rock masses at constant grouting rate was established. Moreover, the viscosity and pressure distribution equations in the slurry diffusion zone were deduced, thus quantifying the relationship between grouting pressure, grouting time, and slurry diffusion distance. On this basis, by using a 3-d finite element program in multi-field coupled software Comsol, the numerical simulation results were compared with theoretical calculation values, further verifying the effectiveness of the theoretical model. In addition, through the analysis of two engineering case studies, the theoretical calculations and measured slurry diffusion radius were compared, to evaluate the application effects of the model in engineering practice. Finally, by using the established theoretical model, the influence of cracking in rock masses on the diffusion characteristics of slurry was analysed. The results demonstrate that the inclination angle of the crack in rock masses and azimuth angle of slurry diffusion affect slurry diffusion characteristics. More attention should be paid to the actual grouting process. The results can provide references for determining grouting parameters of fast-curing grouts in engineering practice.