• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.194-196
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• 2005

A series of inorganic-organic hybrid membranes were prepared with a systematic variation of titanium dioxidenanoparticles content. Their liquid uptake, methanol permeability and proton conductivity as a function of inoranic oxide content were investigated. The results obtained show that the inorganic oxide network decreases the proton conductivity and liquid uptake. It is also found that increase in inorganic oxide content leads to decrease of methanol permeability. In terms of the morphology, membranes are homogeneous and exhibit a good adhesion between inorganic domains and the polymer matrix. The properties of the composite membranes are compared with the standard nafion membrane.

• Journal of Mechanical Science and Technology
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• v.14 no.12
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• pp.1365-1375
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• 2000

Two phase flows have been numerically calculated to analyze plume characteristics and liquid circulation in gas injection through a porous plug. The Eulerian approach has been for formulation of both the continuous and dispersed phases. The turbulence in the liquid phase has been modeled using the standard $textsc{k}$-$\varepsilon$ turbulence model. The interphase friction coefficient has been calculated using correlations available in the literature. The turbulent dispersion of the phase has been modeled by the "dispersion Prand시 number". The predicted mean flows is compared well with the experimental data. The plume region area and the axial velocities are increased with the gas flow rate and with the decrease in the inlet area. The turbulent intensity also shows the same trend. Also, the space-averaged turbulent kinetic energy for various gas flow rates and inlet areas has been obtained. The results are of interest in the design and operation of a wide variety of materials and chemical processing operations.

• Analytical Science and Technology
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• v.11 no.6
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• pp.499-504
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• 1998

An analytical method for the simultaneous measurement of trace Cu, Sn, and Bi in sea water has been investigated by Inductively Coupled Plasma-Mass Spectrometry. Amberlite IRC-718 resin was used as a solid phase in solid-liquid extraction technique for the removal of matrix interferences such as Na, S, P, and other polyatomic ion species. Recoveries of 99.8% for Cu, 99.6% for Sn, and 97.9% for Bi were obtained for the standard spiked sample. The developed method was applied to analysis of trace metals in sea water.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1069-1080
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• 2008

The mechanical characteristic of Lightweight Foamed Soil(LWFS) are investigated in this research. LWFS is composed of the in-suit soil, cement and foam to reduce the unit-weight and increase compressive strength. The unconfined compressive tests are carried out on the prepared specimens of LWFS with various soil types to investigate the relationship between compressive strength of LWFS and physical properties of soil. The result indicate that coefficient of gradation($C_g$) and liquid limit(LL) are more important factor affecting compressive strength than other physical properties of soil and coefficient of gradation($C_g$) and liquid limit(LL) can standard to determine the optical soil among the in-situ soils for LWFS.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.6
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• pp.824-834
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• 1999

Characteristics of two-phase flow and heat transfer were numerically investigated in a submerged gas injection system when temperature of the injected gas was different from that of the liquid. The Eulerian approach was used for both the continuous and dispersed phases. The turbulence in the liquid phase was modeled using the standard $k-\varepsilon$$\varepsilon$ turbulence model. The interphase friction and heat transfer coefficient were calculated from the correlations available in the literature. The turbulent dispersion of the phases was modeled by a "dispersion Prandtl number". In the case with heat transfer where the temperature of the injected gas is higher than the mean liquid temperature, the axial and the radial velocities are lower in comparison with the case of homogeneous temperatures. The results in the present research are of interest in the design and operation of a wide variety of material and chemical processes.

• Bulletin of the Korean Chemical Society
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• v.19 no.6
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• pp.617-618
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• 1998

A simple and reproducible pretreatment method was developed for the determination of dioxins in milk sample. Liquid-liquid extraction (LLE) was used for the initial extraction of the analyte from milk. For the elimination of interferences coextracted from milk, acid treatment followed by multilayer silica gel, and then alumina column clean-up were performed. The clean extract could be obtained without carbon column or high performance liquid chromatographic (HPLC) clean-up procedure. Polychlorinated biphenyles (PCBs) and dioxins were separated on neutral alumina activated at 180 ℃ for 12 hours. The final extract was analyzed by HPLC and high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). The recovery of dioxins spiked in milk at 75-300 ppt level was 83.3-98.9% and their relative standard deviation was 4.1-14%.

• Bulletin of the Korean Chemical Society
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• v.19 no.6
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• pp.619-624
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• 1998

A simple and reproducible pretreatment method was developed for the determination of dioxins in milk sample. Liquid-liquid extraction (LLE) was used for the initial extraction of the analyte from milk. For the elimination of interferences coextracted from milk, acid treatment followed by multilayer silica gel, and then alumina column clean-up were performed. The clean extract could be obtained without carbon column or high performance liquid chromatographic (HPLC) clean-up procedure. Polychlorinated biphenyles (PCBS) and dioxins were separated on neutral alumina activated at 180 ℃ for 12 hours. The final extract was analyzed by HPLC and high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). The recovery of dioxins spiked in milk at 75-300 ppt level was 83.3-98.9% and their relative standard deviation was 4.1-14%.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.277.1-277.1
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• 2003

A high-performance liquid chromatographic method using the liquid extraction procedure was developed for the determination of L -FMAUS. a new L -FMAU derivative, in rat plasma and urine using 3-aminophenyl sulfone as an internal standard. A 100-${\mu}\ell$ aliquot of distilled water containing the L -cysteine (100 mg/$m\ell$) was added to a 100-${\mu}\ell$ aliquot of biological sample. L-Cysteine was employed to protect binding between 5'-thiol of l and protein in the biological sample. (omitted)

• Bulletin of the Korean Chemical Society
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• v.25 no.2
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• pp.233-236
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• 2004

Total impurity analysis of a primary standard solution is one of the essential procedures to determine an accurate concentration of the standard solution by the gravimetry. Bi impurity is determined in Pb standard solutions by inductively coupled plasma mass spectrometry (ICP-MS). The direct nebulization of the Pb standard solution produces a significant amount of the Pb matrix-induced molecular ions which give rise to a serious spectral interference to the Bi determination. In order to avoid the spectral interference from the interferent $^{208}PbH^+$, the hydride generation method is employed for the matrix separation. The Bi hydride vapor is generated by reaction of the sample solution with 1% sodium borohydride solution. The vapor is then directed by argon carrier gas into the ICP after separation from the mixture solution in a liquid-gas separator made of a polytetrafluoroethylene membrane tube. The presence of 1000 ${\mu}$g/mL Pb matrix caused reduction of the bismuthine generation efficiency by about 40%. The standard addition method is used to overcome the chemical interference from the Pb matrix. Optimum conditions are investigated for the hydride-generation ICPMS. The detection limit of this method is 0.5 pg/mL for the sample solutions containing 1000 ${\mu}$g/mL Pb matrix.

• KSBB Journal
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• v.13 no.1
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• pp.77-82
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• 1998

Glutathione(L-$\gamma$ -glutamyl-L-cysteinylglycine, GSH) produced by microbial enzymes was separated by a liquid chromatography. In order to select a resin which would bind GSH efficiently, a batch adsorption experiment was carried out with GSH solution and various resins at pH 8.0 GSH bound to Q-sepharose and QAE-sephadex among anion exchange resins, but the latter was found not to be suitable because of the reduction of resin volume at high salt concentration. Preliminary experiments using a standard solution were carried out to separate GSH. GSH and $\gamma$ -glutamylcysteine were separated from the other constituents by applying step gradient of salt(NaCl) concentration. GSH was successfully separated from $\gamma$ -glutamylcysteine by applying Tris buffer containing 35mM NaCl. Chromatographic separation behaviors for the enzymatic product was similar to that for the standard solution. Separation yields of GSH from the standard solution and enzymatic product solution were 72.6% and 84.4%, respectively.