• Journal of the Korean Ceramic Society
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• v.52 no.1
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• pp.13-18
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• 2015

The fabrication method used for mineral hydrate is similar to that of ALC (autoclaved lightweight concrete), but the fabrication of normal slurry with a considerable amount of a foaming agent is difficult due to material separation and collapse of the slurry. Therefore, the development of fabrication methods for normal slurry is necessary. The final product, mineral hydrate insulation, has excellent thermal properties but poor strength characteristic given the many pores. In this study, in order to fabricate normal slurry, the viscosity and foaming time of the slurry were controlled. The mixing ratio of the starting material and the polypropylene fiber was controlled to improve the strength. Mineral hydrate with polypropylene fiber showed a higher strength than that without this type of fiber. Specifically, the compressive strength of mineral hydrate with 2% polypropylene fiber added to it was more than 40% higher than that without the fiber.

• Journal of Electrochemical Science and Technology
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• v.5 no.4
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• pp.95-104
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• 2014

Electrochemical performance of Li-ion cells with $LiMn_2O_4$ cathodes and graphite anodes with carbonates electrolytes containing quaternary ammonium-based room temperature ionic liquids (ILs) is investigated. Eight different ILs based on tetraalkylammonium, pyrrolidinium or piperidinium cations paired with bis(trifluoromethylsulfonyl)imide or tris(pentafluoroethyl)trifluorophosphate anions are examined in combination with dimethyl carbonate as a main solvent and fluoroethylene carbonate as a solid electrolyte interface forming agent. It is shown that cycling properties of the cells are strongly affected by the content of ILs in the electrolyte mixtures and its increase corresponds to lower discharge capacity retention. Since viscosity and conductivity of ILs are of a great importance for the electrolytes formulation, some kind of combined parameter should be used for the assessment of IL applicability and calculated values of Walden products for neat ILs represent one of the possible options. Besides, positive effect of ILs on reduction of flammability and enhancement of thermal stability of electrolytes in contact with charged electrodes have been demonstrated by means of self-extinguishing time test and differential scanning calorimetry respectively.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.37 no.1
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• pp.37-42
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• 2011

The rheological properties of the aqueous solution of scleroglucan industrially produced by Sclerotium rolfsii at concentrations ranging from 0.1 % to 2 % (w/w) were determined by using brookfield viscometer and rheometer. Gel matrices of scleroglucans were stable over a wide range of pH and ionic strength in the aqueous medium. In the oil dispersion with phytosqualane in oil phase and three kinds of thickening agent in aqueous phase, scleroglucan showed the highest dispersion properties. The synergistic effect between scleroglucan and locust bean gum was also examined. The highest viscosity was obtained for the solution mixture at scleroglucan/locust bean gum weight ratio of 5 : 5. The results of this study suggest the potential of scleroglucan as thickner for a wide variety of cosmetic formulations.

• International Journal of Precision Engineering and Manufacturing
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• v.5 no.1
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• pp.47-54
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• 2004

In this study, the electrorheological (ER) fluid was used as finishing agent. Since the apparent viscosity can be controlled by an electric field, the ER fluid can be one of efficient materials in finishing processes. To finish small 3-dimensional structures such as the aspherical surface in optical elements, the possible arrangement of a tool, part and auxiliary electrode was described. We examined the influence of the addition of a few abrasive particles on the performance of the ER fluid by measuring yield stress and observed the behavior of abrasive particles in the ER fluid by a CCD camera, which had been also theoretically predicted from the electromechanical principles of particles. On the basis of the above results, the steady flow analysis around the rotating micro tool was performed considering the non-uniform electric field. Finally, borosilicate glass was finished using the mixture of the ER fluid and abrasive particles and material removal with field strength and surface roughness were investigated.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.1
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• pp.65-73
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• 2012

Nowadays, the concern on the environmental load of bleaching process gave rise to the process of ECF(elemental chlorine free) and TCF(total clorine free). These sequences are based on oxygen-derived compounds such as oxygen, ozone, and hydrogen peroxide which is used as a typical eco-friendly bleaching agent. In this study, paper mulberry pulp was bleached with hydrogen peroxide and some bleaching process were accompanied with ultrasonication in order to increase the bleaching efficiency. The best bleaching efficiency of paper mulberry pulp was obtained in the condition of hydrogen peroxide and ultrasonication(20 kHz) bleaching system at $45^{\circ}C$ for 30 min. The brightness and kappa number of paper mulberry pulp were gained to 5.09% and 3.52 respectively. and yield was slightly loosed to 2%. Therefore, the efficiency of hydrogen peroxide and ultrasonication bleaching system of paper mulberry pulp was superior to the conventional hydrogen peroxide bleaching system. Magnesium sulfate acted as a bleaching stabilizer for the increasement of yield. As a result, the yield and viscosity were increased to 2.2% and 12% respectively.

• Macromolecular Research
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• v.11 no.4
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• pp.267-272
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• 2003

The isothermal cure reactions of blends of epoxy (DGEBA, diglycidyl ether of bisphenol A)/anhydride resin with polyamide copolymer (poly(dimmer acid-co-alkyl polyamine)) or PEI were studied using differential scanning calorimetry (DSC). Rheological measurements have been made to investigate the viscosity and mechanical relaxation behavior of the blends. The reaction rate and the final cure conversion were decreased with increasing the amount of thermoplastics in the blends. Lower values of final cure conversions in the epoxy/thermoplastic blends indicate that thermoplastics hinder the cure reaction between the epoxy and the curing agent. Complete miscibility was observed in the uncured blends of epoxy/thermoplastics up to $120^{\circ}C$ but phase separations occurred in the early stages of the curing process at higher temperatures than $120^{\circ}C$. According to the rheological measurement results, a rise of G' and G" at the onset of phase separation is seen. A rise of G' and G" is not observed for neat epoxy system since no phase separation is seen during cure reaction. At the onset of phase separation the rheological behavior was influenced by the amount of thermoplastics in the epoxy/thermoplastic blends, and the onset of phase separation can be detected by rheological measurements.

• Clean Technology
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• v.14 no.4
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• pp.281-286
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• 2008

Absorption rate of carbon dioxide was measured in the aqueous polyacrylamide (PAA) solution containing triethanolamine (TEA) of $0{\sim}2.0\;kg\;mol/m^3$ in a flat-stirred vessel with an impeller of 0.05 m and agitation speed of 50 rpm at $25^{\circ}C$ and 101.3 kPa. The chemical absorption rate of $CO_2$ was estimated by mass transfer mechanism based on the film theory using the physicochemical properties containing the liquid-side mass transfer coefficient of $CO_2$ and the kinetics of reaction between $CO_2$ and TEA to compare with the measured rate. The aqueous PAA solution acted as a reducing agent by viscoelastic property of non-Newtonian liquid based on the same viscosity of the solution.

• Environmental Engineering Research
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• v.11 no.4
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• pp.208-216
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• 2006

In order to create a single flocculant/dual flocculation system, polyacrylamide-co-trimethyl ammonium ethyl acrylate chloride (TAEAC) polymers with varying molecular weights and structures were prepared for use of flocculants. The higher the cationic density of the polymer is higher, the higher was the conversion rate and the ratio of monomer. An acrylamide as nonionic monomer was less reactive than a TAEAC as cationic monomer. The branched polymer which was polymerized with a cross-linking agent, N, N-methylene bis-acrylamide had a higher stability and higher viscosity than a linear polymer but its dewatering efficiency was poor in a single flocculation system. In the case of single flocculant/dual flocculation, the branched polymer has better flocculation efficiency and the water content of the dewatered cakes was lower than the others, as the result of a re-flocculation effect. The optimum conditions for dual flocculation are a sequence in which the $1^{st}$ and $2^{nd}$ dosage are 75% and 25%/total dosage of a single flocculation system. The dewatering efficiency of a dual flocculation system is improved considerably from 10 to 25% under the experimental conditions used herein.

• Journal of the Korean Applied Science and Technology
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• v.10 no.2
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• pp.81-90
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• 1993

The Surfactants composed of acylated aterocollagen which is produced by the acylation of the side chain amino radicals of aterocollagen with an aliphatic acid having 12 to 18 carbon atoms will be discussed in this study. This condensation is done at moderate reaction temperature (<$25^{\circ}C$) in aqueous alkaline solution. The products of this reaction were identified by UV/VIS spectroscopy and infrared spectroscopy. For these compounds, surface active properties and physical properties including isoelectric point, Krafft point, surface tension, critical micelle concentration(cmc), foaming power, viscosity behaviour, water holding capacity, skin irritation and emulsifying power were measured respectively. The experimental results received that the products have a good emulsifying power, excellent water holding capacity while having low skin irritation. Thus, these derivatives will be expected to be used as an emulsifying agent for O/W type cosmetic emulsion.

• ETRI Journal
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• v.32 no.3
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• pp.414-421
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• 2010

The interconnection mechanisms of a smart anisotropic conductive adhesive (ACA) during processing have been characterized. For an understanding of chemorheological mechanisms between the fluxing polymer and solder powder, a thermal analysis as well as solder wetting and coalescence experiments were conducted. The compatibility between the viscosity of the fluxing polymer and melting temperature of solder was characterized to optimize the processing cycle. A fluxing agent was also used to remove the oxide layer performed on the surface of the solder. Based on these chemorheological phenomena of the fluxing polymer and solder, an optimum polymer system and its processing cycle were designed for high performance and reliability in an electrical interconnection system. In the present research, a bonding mechanism of the smart ACA with a polymer spacer ball to control the gap between both substrates is newly proposed and investigated. The solder powder was used as a conductive material instead of polymer-based spherical conductive particles in a conventional anisotropic conductive film.