• Journal of the Korean Applied Science and Technology
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• v.32 no.4
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• pp.789-794
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• 2015

In this study, we investigated the stability with respect to the Langmuir-Blodgett(LB) monolayer films of stearic acid and phospholipid(L-${\alpha}$-dimyristoylphosphatidyl choline, DMPC) mixture. LB films of stearic acid and DMPC monolayer were deposited by the LB method on the indium tin oxide(ITO) glass. The electrochemical properties measured by cyclic voltammetry with three-electrode system in $0.05N\;NaClO_4$ solution, -0.3 V initial, 1650 mV switching potential and -1350 mV final potential. As a result, monolayer LB films of stearic acid and phospholipid mixture was appeared on irreversible process caused by the oxidation current from the cyclic voltammogram. Diffusion coefficient (D) of stearic acid and DMPC mixture(molar ratio 1:1, 1:2, 1:3) was calculated $1.4{\times}10^{-3}$, $1.7{\times}10^{-3}$ and $1.6{\times}10^{-3}(cm^2/s)$ in $0.05N\;NaClO_4$ solution, respectively.

• Korean Journal of Food Science and Technology
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• v.24 no.2
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• pp.111-116
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• 1992

Production of cocoa butter equivalent fat (CBE) from palm oil and stearic acid by reverse micelle lipase reaction system was studied. Qualitative and quantitative analyses of triglycerides were performed by HPLC. The reaction conditions for maximum conversion from triolein and stearic acid to 1-stearoyl-2,3-dioleoyl glycerol(SOO) and 1,3-distearoyl-2-oleoyl glycerol(SOS) were as follows: a molar ratio of water/Aerosol OT, 10; triolein, 30 mM; stearic acid, 90 mM; pH, 7.5; and temperature, $50^{\circ}C$. By lipase in reverse micellar system containing palm oil and stearic acid, 1,3-dipalmitoyl-2-oleoyl glycerol(POP), 1-palmitoyl-2,3-dioleoyl glycerol(POO) and SOO decreased, but large amounts of 1-palmitoyl-2-oleoyl-3-stearoyl glycerol(POS) and SOS was formed.

• Fire Science and Engineering
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• v.25 no.6
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• pp.190-195
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• 2011

Effects of ethylene-propylene diene monomer (EPDM)/polypropylene (PP), zinc oxide, stearic acid, and clay on the combustive properties based on EPDM/PP were investigated. The EPDM/PP/clay nanocomposites was compounded to prepare specimen for combustive analysis by cone calorimeter (ISO 5660-1). It was found that the combustive properties in the nanocomposites decreased due to the fire resistance compared with unfilld EDPM/PP. The nanocomposites showed the lower peak heat release rate (PHRR) than that of virgin EPDM/PP, while stearic acid for softening ruber increased the mean heat release rate (MHRR) by itself, combustible.

• Journal of the Korean Chemical Society
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• v.28 no.1
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• pp.41-46
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• 1984

To preconcentrate trace elements, microgram amounts of 5 heavy metals (Cu, Co, Ni, Zn and Cd) were precipitated with 8-hydroxyquinoline (oxine) and metal oxinates were extracted with stearic acid. And then each of the molten stearic acid extract with stearic acid. And then each of the molten stearic acid extract was poured into a glass ring and cooled for specimen preparation. The obtained specimens were analyzed by X-ray fluorescene spectrometry. And then conditions of precipitation formation and extraction, reproducibility, sensitivity and detection limit were observed. The relative standard deviation of specimen preparation was 1.0~5.7% and the detection limit was 5~$50{\mu}g$/100ml. The proposed preconcentration procedure exhibited a considerable inhancement and simplicity in preparing specimens.

• Journal of the Korean Chemical Society
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• v.18 no.5
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• pp.354-357
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• 1974

The critical micelle concentration(CMC) of sucrose monostearate is determined between 20 and $40^{\circ}C$, and the effect caused by the addition of sucrose distearate on the CMC is also studied. It is found that, when both of monoester and diester are dissolved, the curve of surface tension of the solution versus the concentration shows a discontinuity at about 40 dyne $cm^{-1}$ of the surface tension. The discontinuity is interpreted as the associate formed between monoester and diester changes its surface orientation at this region.

• Journal of the Korean Chemical Society
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• v.37 no.6
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• pp.570-576
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• 1993

1-, 3-, 9-, and 21-Monolayer Langmuir-Blodgett(LB) films of stearic acid were deposited on silver-coated glass slides at the surface pressure of 30 mN/m. Fourier transform infrared(FTIR) reflection-absorption spectra (RAS) of these LB films were recorded at various temperatures from 31 to $72^{\circ}C.$ The spectra at $31^{\circ}C$ exhibited characteristic features of highly perpendicular orientation of the hydrocarbon chain. In the 1-monolayer LB film, the C=O stretching band was not observed, presumably due to the image dipole effect on the silver surface. In the 1-and 3-monolayer LB films, the trans isomer of stearic acid was prominent, but the cis isomer was dominant in the 21-monolayer LB film. FTIR-RAS measurements at an elevated temperature indicated that the chain melting temperature increases and approached to the bulk melting point with increasing the number of monolayer, except for the 1-monolayer LB film which has a higher melting temperature than the 3-monolayer film due to the strong interaction with the silver substrate.

• Journal of the Korean Chemical Society
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• v.25 no.4
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• pp.283-290
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• 1981

The reaction rates for the transesterification reaction were measured on the excess sucrose with the five fatty acid methyl ester systems such as methyl laurate, methyl myristate, methyl palmitate, methyl stearate and methyl oleate at temperature range of $50^{\circ}C$ to $90^{\circ}C$ in N,N-dimethylformamide solvent and potassium carbonate as a catalyst. Their activation parameters as well as rate constants were calculated from these measurements. And these reactions were found to be pseudo-first order and depended mainly on the structural changes in fatty acid residue of methyl esters. Also their reactions were found to be of enthalpy-controlled, which were disfavored in the order of methyl laurate, methyl myristate, methyl palmitate, methyl oleate and methyl stearate. Correspondingly their activation energies were 9.3, 9.9, 10.3, 10.9 and 11.1 kcal/mole, respectively.

• Korean Journal of Food Science and Technology
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• v.16 no.2
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• pp.165-168
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• 1984

The three kinds of Kochujang were prepared with liquid koji equivalent to 30, 50 and 70% of brewing water and the composition of fatty acid and alcohols in the Kochujang aged at $25^{\circ}C$ for 3 months were compared with solid koji Kochujang. Palmitic, oleic and linoleic acid were found in all Kochujangs; but myristic, stearic and linolenic acid were detected in only the 50 and 70% liquid koji group. The predominant fatty acid of all Kochujang was linoleic acid, followed by oleic and palmitic acid. The total percentage of linoleic acid in the Kochujang was 58.47-83.39%. Linolenic, myristic and stearic acid were less than 3%. Ethyl, iso-butyl and iso-amyl alcohol were detected from all kinds of Kochujang. Iso-propyl alcohol was found in the Kochujang prepared from solid koji and 30% liquid koji. The contents of iso-butyl and iso-amyl alcohol were high in solid koji Kochujang and 50% liquid koji Kochujang. There were no significant difference in the contents of ethyl alcohol among tested Kochujangs.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.241-246
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• 2001

Vortices terminating at free surface have been investigated extensively. Most of investigations, however, are focused on surface parallel vortices and little has been known about surface normal vortex or columnar vortex. Visualized experimental results utilizing LIF technique are discussed for the purpose of characterization of columnar vortex interacting with a clean and a contaminated free surfaces and a solid body interface in the present investigation. The results reveal that surface tension changes due to surface contamination although bulk viscosity remains constant and eventually the behavior of a columnar vortex interacting with a contaminated free surface and a solid body interface are totally different from the clean free surface case.

• Journal of the Korean Ceramic Society
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• v.46 no.4
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• pp.365-371
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• 2009

It is well known that the properties of concrete such as the compressive strength, water permeability, water tightness and durability are affected by micro-structure in hardened cement paste. Especially, for durability of concrete, watertightness of cementitious materials is the most critical property among various properties. Recently, many types of materials as organic and/or inorganic materials are used for watertightness of concrete. In this study, The effect of Stearic Acid at $0.5\;wt%{\sim}3.0\;wt%$ adding ratios on the hydration and watertightness property of cement were investigated. And we also discussed the changing of microstructure in hardened cement paste by addition of Stearic Acid. Cement paste with Stearic Acid showed improvement of watertightness by reducing of cement total pore volume and decomposition of Stearic Acid.