• Applied Chemistry for Engineering
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• v.31 no.4
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• pp.429-437
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• 2020

In this study, a cationic gemini surfactant was synthesized using isosorbide, in order to modify the alkyl chain length in the range of C₁₀~C₁₆. The c.m.c and surface tension of the synthesized cationic gemini surfactant were measured to be in the ranges of 5.13 × 10^-4~1.62 × 10^-4 mol/L and 31.86~37.41 dyne/cm, respectively. The surface tension increased with increasing the length of the alkyl group. In addition, as the area per molecule occupied by the surfactant adsorbed on the interface increased with the reduced extent of adsorption, the bubble generation at the air-water interface decreased. The emulsifying capacity in benzene was maintained above 60 ± 5% after 8 h while that in soybean oil tended to decrease above 50 ± 5%. The performance was superior in benzene, a highly hydrophobic substance, and the emulsion stability was shown to be consistent beyond 1 h during the preparation of pre-emulsion in oil and water. The antimicrobial activity was dependent on the length of the hydrophobic chain of the synthesized cationic gemini surfactant due to the increased size of the clean zone in Escherichia coli (E.coli) and Staphylococcus aureus.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3276-3286
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• 1994

In most direct contact liquid-liquid heat exchangers, oil or hydrocarbon with a density less than water is normally used as dispersed working fluid. The main difficulty that arises with this arrangement lies in the control of the interface at the top of the column. When it is connected with a solar collector which uses water as its working fluid, the main difficulties arise from the fact that the water can be frozen during winter time. In order to solve these problems and to demonstrate the technical feasibility of a direct contact liquid-liquid heat exchanger, liquids heavier than water with low freezing temperature has been utilized as dispersed phase liquids in a small laboratory scale model made of pyrex glass. In the present investigation, dimethyl phthalate(C/sub 6/H/sub 4/)COOCH/sub 3/)/sub 2/) and diethyl phthalate (C/sub 6/H/sub 4/(CO/sub 2/C/sub 2/H/sub 5/)/sub 2/) are utilized as heavy dispersed phase working fluids. The results of the present investigation the technical in the utilization of heavier dispersed working liquid in the spray-column liquid-liquid heat exchanger for a solar system. The overall average temperature difference along the column is found to be almost half of the initial temperature difference between the dispersed and the continuous phase. Despite the fact that the two phthalates tested in the experiment differ significantly in some of their physical properties, the volumetric heat transfer coefficients in terms of dispersed fluid superficial velocities were found to be similar for both phthalates tested.

• Journal of Life Science
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• v.18 no.8
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• pp.1159-1163
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• 2008

The purpose of this study was to establish a high-throughput assay method capable of estimating specific lipase activity at oil-water interface. The method is based on the fact that fluorescence intensity of fluorescein is affected by pH. The pH-dependence might be used to monitor pH change caused by the release of fatty acid through the action of lipase. Assay was performed by incubating a reaction mixture containing oil emulsion, fluorescein and enzyme and by monitoring fluorescence intensity periodically. Fluorescence intensity decreased linearly with a rate proportional to the enzyme amount. Linear relationship was observed between enzyme amount and reaction rate which was calculated from a graph of fluorescence change against time. The assay was possible at different pH conditions in the range of pH 6.0-8.0.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.524-532
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• 2018

In this study, two types of amino acids-based anionic biosurfactants such as potassium cocoyl glutamate (CTK) and sodium cocoyl glutamate (CTN) were synthesized from coconut oils and the structure elucidation of CTK and CTN was carried out by using FT-IR, $^1H-NMR$ and $^{13}C-NMR$ spectrophotometries. Measurements of interfacial properties such as static and dynamic surface tensions and emulsification activity showed that both CTK and CTN were surface-active and effective in lowering the interfacial free energy. In particular, the CTK surfactant was found to be more efficient in reducing the interfacial free energy since the larger number of CTK molecules was preferentially adsorbed at the air-water interface due to the higher hydrophobicity and larger mobility of CTK than those of using CTN, indicating possible uses in cosmetics and household products formulation.

• Journal of the Korean Chemical Society
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• v.40 no.1
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• pp.1-10
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• 1996

Gibbs' adsorption isotherms are studied to assay the structural effects of ethylene oxide (EO) and propylene oxide (PO) moieties on the molecular area and the interfacial tension behavior of molecules at the interface. Several industrial alcohols and isomerically pure alcohols, which have a general stucture of C4H9O(EO)m(PO)nH, are examined for their cosurfactant properties. They are high molecular weight alcohols and more surface active than the cosurfactants usually used. Results show that the number and the sequence of EO and PO units significantly affect the molecular areas and the interfacial tension (IFT) behavior of these molecules at the water/oil interface. The following conclusions are drawn from the result: 1) PO is more efficient in lowering the IFT and less effective in adsorption than EO. 2) For molecules having the same molecular weight but different structures, smaller molecules are more efficient in lowering the IFT. 3) When more EO, PO, or both units are added to the same hydrophobe, the molecule become bigger and more efficient in lowering the IFT.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2000.09a
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• pp.93-103
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• 2000

The concrete plug in an underground cavern prevents the stored product (oil, gas, etc) from leaking and the excessive show of underground water, so it plays an important role in construction and operation of the storage cavern. Additionally, it should maintain its stability under every possible loading condition. Once the plug is constructed, the cavern is isolated from the external access. Therefore, mechanical and hydraulic consideration should be made in construction to fulfill its function. Therefore, in this study, numerical analyses were conducted to study the optimal shape and thickness of the plug with respect to the various conditions of installation depth, the shape of the plug, in-situ stress ratio (K), the condition of rock-plug interface, and the effect of Excavation Damaged Zone (EDZ). This paper also presents the effect of slot depth on the hydraulic behavior of the plug. These analyses were carried out by using the 2-dimensional finite difference code, rm FLAC, and the 3D code, m FLA $C^{3D}$./.

• Tunnel and Underground Space
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• v.10 no.3
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• pp.344-354
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• 2000

The concrete plug in an underground cavern prevents the stored product (oil, gas, etc) from leaking and the excessive inflow of underground water, so it plays an important role in construction and operation of the storage cavern. Additionally, it should maintain its stability under every possible loading condition. Once the plug is constructed, the cavern is isolated from the external access. Therefore, mechanical and hydraulic consideration should be made in construction to fulfill its function. Therefore, in this study, numerical analyses were conducted to study the optimal shape and thickness of the plug with respect to the various conditions of installation depth, the shape of the plug, in-situ stress ratio (K), the condition of rock-plug interface, and the effect of Excavation Damaged Zone (EDZ). This paper also presents the effect of slot depth on the hydraulic behavior of the plug. These analyses were carried out by using the 2-dimensional finite difference code, rm FLAC, and the 3D code, rm FLAC$\^$3D/.

• Journal of Digital Contents Society
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• v.9 no.4
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• pp.707-715
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• 2008

The ocean ecosystem and the marine farms were damaged after latest oil spill in Taean. They suffered heavily due to the expansion of the red tide on the coast and the sudden changes in water temperature. We should develop the way to deal with various factors to reduce the damage. In this paper, real time data with which are supplied us through many kinds of sensors on measure equipments will be processed to the visualized shape. Simple numeric data and 2D graph will be changed 2D or 3D graphic objects and animations using WPF, a new effect method in user interface area. This visualization system for environmental data shows us various pictures and offers multimedia data communication.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.1
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• pp.1-7
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• 2019

We introduce to prepare liquid crystalline emulsion composed of cetearyl alcohol, cetyl palmitate, sorbitan palmitate, sorbitan olivate, ceramide and so on which can enforce interface between oil-based particle and water phase. In terms of structural analysis, the stability of the liquid crystalline emulsion including ceramide, which is immisible ingredient, at high temperature was proved by polarized microscope, cryo-SEM, small-angle x-ray scattering, in addition to viscometer and static light scattering by physical analysis.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.4
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• pp.459-466
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• 2018

Hazardous and Noxious Substances (HNS) are defined as substances that are likely to create a significant impact on human health and marine ecosystem when they are released into the marine environment. Recently, as the volume of HNS transported by ships increases, the rate of leakage accidents also increases. Therefore, research should be conducted to control and monitor sunken materials from the viewpoint of technology development for hazardous material leakage accident response. In this paper, acoustic detection experiments were carried out using HNS substitute materials in order to confirm the possibility of acoustic detection of sunken HNS on the sediment. The castor oil, which has a similar acoustic impedance with chloroform, is used as a substitute. 200 kHz high frequency signals were used to discriminate the reflected signals and measure reflection loss from the interface between water and castor oil. The reflection loss measured is in good agreement with the modeling results, showing a possibility of acoustic detection for sunken HNS.