• Mass Spectrometry Letters
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• v.12 no.4
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• pp.186-191
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• 2021

A new method for chemical separation of light rare-earth elements (LREEs) using gas-pressurized extraction chromatography (GPEC) is described. GPEC is a microscale column chromatography system that features a constant flow of solvents, which is created by pressurized nitrogen gas. The separation column with a Teflon tubing was packed with LN resin. The proposed GPEC method facilitates production of lesser chemical wastes and faster separation owing to the use of low solvent volume compared to traditional column chromatography. We evaluated the separation of Ba, La, Ce, and Nd using various elution solvents. The column reproducibility of the proposed GPEC system ranged from 2.4% to 4.9% with RSDs of recoveries, and the column-to-column reproducibility ranged from 3.1% to 6.3% with RSDs of recoveries. The proposed technique is robust, and it can be useful for the fast separation of LREEs.

• Resources Recycling
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• v.22 no.6
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• pp.33-40
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• 2013

Due to the environmental problem caused by plastics largely used in various fields, the importance of recycling is being emphasized. A research on material separation of ABS and PS mixed plastic waste, using a triboelectrostatic separator, was carried out for recovery the ABS. As a results of research on charging characteristic for choosing charging material, it was confirmed that ABS was optimum charging material for a tribo-charger in the material separation of ABS and PS. In the material separation using ABS charger, ABS grade of 99.5% and recovery of 92.5% were achieved at 20 kV, splitter position +2 cm from the center and 30% relative humidity. Therefore, material separation technique for recycling ABS and PS mixed plastic waste was established.

• International Journal of Fluid Machinery and Systems
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• v.2 no.3
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• pp.215-222
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• 2009

Jets issuing through small holes in a wall into a freestream has proven effective in the control of flow separation. This technique is known as the vortex generator jet (VGJs) method. If a precursor signal of separation is found, the separation control system using VGJs can be operated just before the onset of separation and the flow field with no separation is always attained. In this study, we measured the flow field and the wall static pressure in a two-dimensional diffuser to find a precursor signal of flow separation. The streamwise velocity measurements were carried out in the separated shear layer and spectral analysis was applied to the velocity fluctuations at some angles with respect to the diffuser. The pattern of peaks in the spectral analysis changes as the divergence angle increases over the angle of which the whole separation occurs. This change in the spectral pattern is related to the enhancement of the growth of shear layer vortices and appears just before the onset of separation. Therefore, the growth of shear layer vortices can be regarded as a precursor signal to flow separation.

• The Journal of the Petrological Society of Korea
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• v.24 no.4
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• pp.365-371
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• 2015

The rare earth element(REE)s play an important role in understanding of rock formation and evolution because of their similar geochemical behaviors. Sm and Nd are more useful than other REEs because Sm-Nd isotopic system has important applications for geochemical interpretation like age dating and crustal evolution. These studies require a chromatographic technique for Sm and Nd separation from the geological samples. Ln-resin method using 0.25 M HCl as the eluent is widely used for Nd separation. However, this technique has a disadvantage of the poor elemental selectivity that the Nd fraction contains Ce as a tailing of the previous fraction. This technical report is a comparison study on the effect of eluent concentration between 0.25 M HCl and 0.15 M HCl on the separation of Nd with Ln-resin method for improving the technique of Nd separation. The results showed that the separation of Ce and Nd using 0.15M HCl as the eluent was not effective compared to the separation using 0.25 M HCl. In this experiment, we could confirm that the dilution of eluent might not be effective on the high purity separation of Nd with Ln-resin method.

• The Journal of the Acoustical Society of Korea
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• v.21 no.4E
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• pp.146-155
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• 2002

We present a new technique for achieving source separation when given only a single charmel recording. The main idea is based on exploiting the inherent time structure of sound sources by learning a priori sets of time-domain basis functions that encode the sources in a statistically efficient manner. We derive a learning algorithm using a maximum likelihood approach given the observed single charmel data and sets of basis functions. For each time point we infer the source parameters and their contribution factors. This inference is possible due to the prior knowledge of the basis functions and the associated coefficient densities. A flexible model for density estimation allows accurate modeling of the observation, and our experimental results exhibit a high level of separation performance for simulated mixtures as well as real environment recordings employing mixtures of two different sources. We show separation results of two music signals as well as the separation of two voice signals.

• The Journal of the Acoustical Society of Korea
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• v.21 no.4
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• pp.146-146
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• 2002

We present a new technique for achieving source separation when given only a single channel recording. The main idea is based on exploiting the inherent time structure of sound sources by learning a priori sets of time-domain basis functions that encode the sources in a statistically efficient manner. We derive a learning algorithm using a maximum likelihood approach given the observed single channel data and sets of basis functions. For each time point we infer the source parameters and their contribution factors. This inference is possible due to the prior knowledge of the basis functions and the associated coefficient densities. A flexible model for density estimation allows accurate modeling of the observation, and our experimental results exhibit a high level of separation performance for simulated mixtures as well as real environment recordings employing mixtures of two different sources. We show separation results of two music signals as well as the separation of two voice signals.

• Bulletin of the Korean Chemical Society
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• v.22 no.6
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• pp.616-622
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• 2001

Split-flow thin (SPLITT) cell Fractionation(SF) is a technique that allows separation of particulates and macromolecules into two fractions. A gravitational SF(GSF) system is constructed and tested for its applicability for separation of dust and ground water particulates. When tested with polystyrene latex particles, experimental data were in good agreements with theory. The 9.8 and 21.4㎛ polystyrene particles were successuflly separated in a continuous mode, where the mixture is continuously fed into the GSF channel allowing separation in a large sacle. The GSF system is successfully applied to continuous separation of dust and ground water particels based on the sedimentation coefficient, which is closely related to the particle size. The separations were confirmed by microscopy and energy-dispersive X-ray (EDX) analysos.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.4
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• pp.324-331
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• 2014

The sensor configuration of the magnetostrictive guided wave system can be described as a single continuous transducing element which makes it difficult to separate the individual modes from the reflected signal. In this work we develop the mode decomposition technique employing chirplet transform based on the maximum likelihood estimation, which is able to separate the individual modes from dispersive and multimodal waveform measured with the magnetostrictive sensor, and estimate the time-frequency centers and individual energies of the reflection, which would be used to locate and characterize defects. Simulation results on a carbon steel pipe are presented, which show the accurate mode separation and more discernible time-frequency representation could become enabled using the proposed technique.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1683-1684
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• 2008

For direct detection of microbes in air, samples have to be collected but environmental particles such as dust are also trapped in such samples. Therefore the isolation of target bacteria from non-biological materials of similar size is of great importance in the identification of such organisms. Dielectrophoresis is an emerging technique that can rapidly separate cells in microfluidics. In this paper we proposed a new method for the separation of airborne microbes using condensation and dielectrophoresis. This system could be used as a continuous flow through separation system for various particles and utilized as a pretreatment technique for microbe detection.

• YAKHAK HOEJI
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• v.41 no.5
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• pp.539-546
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• 1997

Capillary electrophoresis (CE) is perceived as an attractive tool for the analysis of pharmaceuticals and biological materials because of their high separation efficiency, easy separation and low running cost. New concept of micellar electrokinetic capillary chromatography (MECC) expanded the application of CE to the separation of neutral molecules. Validation of CE as an analytical technique for quality control of pharmaceuticals should be confirmed by quantitative analysis and the peak confirmation. In this study, the quantitative analyses of various types of neutral, acidic and basic components (acetaminophen, caffeine, ascorbic acid, riboflavin, thiamine, chlorpheniramine, phenylpropanolamine, dl-methylephedrine and dextromethorphan) in complex cold medicines have been accomplished using CE. Combined methods of MECC using SDS and capillary zone electrophoresis lowering the pH of running buffer were adopted to determine the ingredients in capsule type or liquid formula complex medicines without particular sample pretreatment. The results indicate that CE is a promising technique for quality control analysis of pharmaceuticals as a validation method.