• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2005년도 국제학술심포지움 The 44th Annual Meeting of Korean Society for Life Science
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• pp.178-178
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• 2005

• Korea-Australia Rheology Journal
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• 제17권4호
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• pp.157-164
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• 2005

Hydrodynamic characteristic of surfactant drag-reducing flows is still not fully understood. This work investigated the temperature and diameter effect on hydrodynamic characteristic of cationic surfactant drag reducing flows in pipes. Solution of oleyl bishydroxyethyl methyl ammonium chloride (Ethoquad O/12), 900 ppm, as a cationic surfactant and sodium salicylate (NaSal), 540 ppm, as a counter-ion was tested at 12, 25, 40, and $50^{\circ}C$ in pipes with diameter of 13, 25, and 40 mm. Drag reduction effectiveness of this surfactant solution was evaluated in 25 mm pipe from 6 to $75^{\circ}C$. Rheological characteristic of this solution was measured by stress control type rheometer with cone-and-plate geometry. Scale-up laws proposed by previous investigators were used to evaluate the flow characteristic of the solution. It was found that this surfactant solution has clear DR capability until $70^{\circ}C$. Result of this work suggested that temperature has a significant influence in changing the hydrodynamic entrance length of surfactant drag reducing flows. From rheological measurement, it was found that the solution exhibits Shear Induced Structure at all temperatures with different degree of peak viscosity and critical shear rate.

• Bulletin of the Korean Chemical Society
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• 제28권9호
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• pp.1588-1590
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• 2007

• Bulletin of the Korean Chemical Society
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• 제12권3호
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• pp.253-254
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• 1991

• Bulletin of the Korean Chemical Society
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• 제28권6호
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• pp.1021-1030
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• 2007

The effects of the creamide III (CER3) and cholesterol (CHOL) on the structure of a non-hydrous distearoyl phosphatidylcholine (DSPC)-based lamellar liquid crystal (LC) hydrated by only propylene glycol (PG) without water were investigated by differential scanning calorimetry (DSC), X-ray diffractions (XRDs), and polarized microscope (PM). As soon as CER3 was incorporated into the lamellar phase, the characteristic LPP was appeared as well as the characteristic SPP, and the formation of separated CER3 crystalline phase was observed depending upon the increase of CER3 content by XRDs. Also, by DSC, it was shown that the increase of CER3 made the monotectic thermal transition be changed to the eutectic thermal transition which indicates the formation of separated CER3 crystalline phases and the main transition temperatures (Tc1) to be gradually decreased and the enthalpy change (ΔH) to be linearly increased. Incorporating CHOL, the formation of LPP and SPP showed almost similar behaviors to CER3, but incorporating small amounts of CHOL showed the characteristic peaks of CHOL which meant the existence of crystalline CHOL phase due to the immiscibility of CHOL with DSPC swollen by PG differently from CER3, and increasing CHOL made the intensity of the 1st order diffraction for LPP weakened as well as the intensities of the characteristic diffractions for DSPC. Also, in the results of DSC, it showed more complex thermal behaviors having several Tc than CER3 due to its bulky chemical structure. In the present study, the inducement of CER3 and CHOL as other lipids present in human stratum corneum (SC) into a non-hydrous lamellar phase is discussed in terms of the influence on their structural and thermal transition.

• 반도체디스플레이기술학회지
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• 제11권2호
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• pp.75-80
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• 2012

Polymer composites which have electrical properties have been studied in various industries. The Multi-walled carbon nanotube (MWCNT) are thought to be reinforcements for polymers because of their high aspect ratio and specially mechanical, thermal and electrical properties. We introduced MWCNT and impact modifier in order to improve thermal and mechanical properties of Polyphenylene sulfide (PPS) and give electric characteristic to PPS. The thermal properties were investigated by Differential scanning calorimeter (DSC) and Thermogravimetric analysis (TGA). The morphology, mechanical properties and electrical characteristic were performed by Field emission scanning electron microscopy (FE-SEM), Izod impact tester and surface resistance meter. As a result, we could find that the PPS/MWCNT composites have high conductivity and good mechanical properties than neat PPS resin.

• Journal of Mechanical Science and Technology
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• 제19권9호
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• pp.1821-1832
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• 2005

This study realizes the conceptual method to predict combustion instability in actual full-scale combustion chamber of rocket engines by experimental tests with model (sub-scale) chamber. The model chamber was designed based on the methodologies proposed in the previous work regarding geometrical dimensions and operating conditions, and hot-fire test procedures were followed to obtain stability boundaries. From the experimental tests, two instability regions are presented by the parameters of combustion-chamber pressure and mixture (oxidizer/fuel) ratio, which are customary for combustor designers. It is found that instability characteristics in the chamber with the adopted jet injectors can be explained by the correlation between the characteristic burning or mixing time and the characteristic acoustic time: In each instability region, dynamic behaviors of flames are investigated to verify the hydrodynamically-derived characteristic lengths of the jet injectors. Large-amplitude pressure oscillation observed in upper instability region is found to be generated by lifted-off flames.

• Bulletin of the Korean Chemical Society
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• 제22권8호
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• pp.867-871
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• 2001

We have studied the characteristic wave propagation in 1,4-CHD-Bromate-Ferroin reaction system and we have examined the bead size effect on the wave propagation of the system by adopting a half-divided Petri dish which is separated into two parts by the size of cation-exchange resin. It has been done to understand the reaction process inducing the characteristic wave behavior in the system. The characteristic wave behavior of the system is in the spontaneous induction of a revival wave with a long time lag. We have obtained a result that the revival wave is not affected by the size of catalyst-doped beads while the initially induced wave is influenced by the size of beads. It means that the two waves are induced by different reaction processes each other and the revival wave is induced by an uncatalyzed reaction process.

• Bulletin of the Korean Chemical Society
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• 제22권6호
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• pp.559-564
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• 2001

A method for calculating the main characteristics of a potentiometric titration curve in a carboxylic ion exchanger has been investigated. The potentiometric titration curves of simple electrolyte and ion exchangers (polyelectrolytes) showed a great difference between them. The acidity parameters of the ion exchangers, the thermodynamic constant (pK0), apparent equilibrium constant (K), and correction for the apparent equilibrium constant (b), were introduced and used to express the characteristics of the carboxylic ion exchanger. A characteristic equation related to the acidity parameters of the ion exchangers systems was derived. A fibrous carboxylic cation exchanger was used and potentiometric titration curves at different concentrations of the supporting electrolyte were obtained . To prove the validity of the characteristic equation, the concentration of the supporting electroyte was varied. In the present study, good agreement between the data points and the fitted curves was found in all the cases. The g (number of moles of alkali to 1 g of ion exchanger) of carboxylic ion exchanger was calculated from the concentration of supporting electrolyte (C), pH of the solution, and degree of neutralization of ion exchanger (x).

• Nuclear Engineering and Technology
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• 제54권8호
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• pp.2809-2818
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• 2022

In this investigation work, liquid-liquid extraction (L.L.E) through three distinctive frameworks have been examined for assurance of slip velocity (S.V), and characteristic velocity (C.V) in a non-center rotating column (N.C.R.C) with a wide extend of factors. Three double frameworks with distinctive interfacial tension comprising of toluene-water (high interfacial tension), n-butyl acetate-water (medium interfacial tension), and n-butanol-water (low interfacial tension) were investigated for tests. Two common relationships for the expectation of S.V and C.V, including phase stream rates, rotor speed, column geometry additionally physical properties, are displayed. The recommended relationships were compared with test information gotten from the writing and the display examination. Findings of this study, the present proposed correlations are more accurate than those previously reported.