• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.328-336
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• 2020

Cesium is a major product of uranium fission, which is the most commonly existed radionuclide in radioactive wastes. Various technologies have been applied to separate radioactive cesium from radioactive wastes, such as chemical precipitation, solvent extraction, membrane separation and adsorption. Crown ethers and calixarenes derivatives can selectively coordinate with cesium ions by ion-dipole interaction or cation-π interaction, which are promising extractants for cesium ions due to their promising coordinating structure. This review systematically summarized and analyzed the recent advances in the crown ethers and calixarenes derivatives for cesium separation, especially focusing on the adsorbents based on extractants for cesium removal from aqueous solution, such as the grafting coordinating groups (e.g. crown ether and calixarenes) and coordinating polymers (e.g. MOFs) due to their unique coordination ability and selectivity for cesium ions. These adsorbents combined the advantages of extraction and adsorption methods and showed high adsorption capacity for cesium ions, which are promising for cesium separation The key restraints for cesium separation, as well as the newest progress of the adsorbents for cesium separation were also discussed. Finally, some concluding remarks and suggestions for future researches were proposed.

• Progress in Superconductivity and Cryogenics
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• v.25 no.3
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• pp.18-21
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• 2023

Pollution of the environment by micro-plastics is now a worldwide problem. Plastics are difficult to decompose and put a great load on the marine environment. Especially a plastic with a size of 5 mm or less is defined as micro-plastic and are carried by ocean currents over long distances, causing global pollution. These are not easily decomposed in the natural environment. In this paper, we aimed to experimentally demonstrate that micro-plastics in seawater can be continuously separated by electromagnetic Archimedes force. Using polyethylene particles of 3 mm in diameter as the separation target, a flow channel was fabricated and separation conditions were investigated by particle trajectory calculations for separation experiments. Based on the calculation results, a solenoid-type superconducting magnet was used as a source of magnetic field to conduct separation experiments of micro-plastics in seawater. Although a high separation rate was assumed in the simulation results, the experimental results did not show any significant improvement in the separation rate due to the electromagnetic Archimedes force. It was found that the gas generated by the electrolytic reaction may have inhibited the migration of the particles.

• Bulletin of the Korean Chemical Society
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• v.29 no.3
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• pp.551-554
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• 2008

An improved HPLC method for the separation of madecassoside isomers (madecassoside and asiaticoside-B) has been developed. The isomers can be separated with high resolution from extracts of Centella asiatica by HPLC using $\beta$-cyclodextrin as a mobile phase added on a $C_{18}$ column. The result shows that the isomers can be separated with a mobile phase consisting of methanol:water (50:50, v/v) with 4 mmol/L $\beta$-CD. To elucidate the mechanism of the separation of madecassoside and asiaticoside-B, this paper studied the separation of their aglycon parts (madecassic acid and terminolic acid), another pair of isomers. The isomers can also be separated with high resolution with a mobile phase consisting of methanol:water (65:35, v/v) with 4 mmol/L $\beta$-CD and the pH of the mobile phase was adjusted to 4. The paper also studied the separation of the two isomers by HPLC using $\alpha$-CD and Glucosyl-$\beta$-CD as a mobile phase additive in order to elucidate the mechanism of the separation process.

• Journal of the Korean Society of Visualization
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• v.18 no.3
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• pp.69-76
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• 2020

In the present study, we investigate the flow separation characteristics of a paraglider canopy model by tuft visualization. The experiment is conducted at Re = 3.3×105 in a wind tunnel large enough to contain the three-dimensional paraglider canopy model, where Re is Reynolds number based on the mean chord length and the free-stream velocity. The flow separation characteristics of the canopy model near the wing root are similar to those of a two-dimensional airfoil with a cross-section similar to the model. On the other hand, near the wingtip region, the flow separation is suppressed by the downwash induced by the wingtip vortex. As a result, as the angle of attack increases, the flow separation occurs from the wing root region of the canopy model and develops toward the wingtip.

• Structural Engineering and Mechanics
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• v.86 no.1
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• pp.29-48
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• 2023

Pounding happens when contiguous structures with differing heights vibrate out of line caused by a seismic activity. The situation is aggravated due to the insufficient separation gap between the structures which can lead to the crashing of the buildings or total collapse of an edifice. Countries around the world have compiled building standards to address the pounding issue. One of the strategies recommended is the introduction of the separation gap between structures. AS1170.4-2007 is an Australian standard that requires 1% of the building height as a minimum separation gap between buildings to preclude pounding. This article presents experimental and numerical tests to determine the adequacy of this specification to prevent the occurrence of seismic pounding between steel frame structures under near-field and far-field earthquakes. The results indicated that the recommended minimum separation gap based on the Australian Standard is inaccurate if low-rise structure in a coupled case is utilised under both near and far field earthquakes. The standard is adequate if a tall building is involved but only when a far-field earthquake happens. The research likewise presents results derived by using the ABS and SRSS methods.

• The Korean Journal of Health Service Management
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• v.4 no.1
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• pp.111-123
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• 2010

The purpose of this study is to examine relations between the job satisfaction and separation intent of radiologists from secondary medical institutes, providing basic information needed to earlier prevent radiologists' separation, improve their quality and effectively manage them. 1. The subjects' job satisfaction was 2.32 points in mean score, which was below the average. 2. Concerning difference in job satisfaction among the subjects in accordance with their demographic characteristics, it was found that radiologists are significantly different among them in job satisfaction according to their age and position. 3. The surveyed radiologists' intent of separation was 2.89 points in mean score, which was not significantly high. 4. Concerning difference in the intent of separation among the participants in accordance with their demographic characteristics, it was found that radiologists are significantly different among them in the intent of separation according to their age, marital status, position and average monthly income. 5. There were significant correlations between the subjects' job satisfaction and intent of separation. In other words, the higher radiologists are in job satisfaction, the lower they are in the intent of separation.

• Resources Recycling
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• v.13 no.1
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• pp.39-46
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• 2004

Triboelectrostatic separation process is a technology that different particles charged after contact and rubbing different materials are separated in a high electric field. This technology has an advantage in that it can be used for separating non-conducting materials such as plastics unlike other electrostatic separation processes. There are two objectives in this study. One is to develop an effective continuous tribo-electrostatic separation process. The other is to apply the developed device for the separation of mixed plastics. Results show that almost all tested plastics reaches over 95% in yield and grade after separation.

• KSBB Journal
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• v.20 no.3
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• pp.164-176
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• 2005

In bioengineering field, current academic trends and informations on crystallization technology for bioproduct separation were summarized. It is essential for utilizing the crystallization technology to understand the fundamental phenomena of crystallization of crystal nucleation, crystal growth, crystal agglomeration and population balance for the design of crystallizers. In general, the crystal nucleation that the crystalline solids occur from the solution is analyzed by Gibb's free energy change in the aspect of thermodynamics and in the present paper the crystal nucleation models based on the above thermodynamics are summarized by their key characteristics. The crystal growth and agglomeration, which have been studied over 50 years and are essential phenomena for separation technology, are reviewed from their basic concept to most leading edge trend of researches. In the material and population balances for the designs of crystallization separation process, the analysis of crystallizers is summarized. Thereon, the present review paper will academically contribute the understanding the crystallization phenomena and the design of the crystallization separation process.

• Korean Membrane Journal
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• v.4 no.1
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• pp.12-19
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• 2002

Nanofiltration of aqueous dye solutions was carried out using polyamide (PA) nanofiltration (NF) composite membranes. The PA composite membranes were prepared by the interfacial polymerization of piperazine (PIP) and trimesoyl chloride (TMC) on the surface of microporous polysulfone (PSf) ultrafi1tration (UF) membranes. After characterization in terms of their permeation performance and surface ionic property, they were used for the separation of dye solutions such as Direct Red 75, 80, 81, and Direct Yellow 8 and 27. The separation conditions were varied to study the factors affecting on the permeation performance of the membranes: different concentrations of dye solutions, operating temperature and time, and flow rate of a feed solution. The surface property of the membrane, especially its ionic property, as a function of operating time was examined with a zeta-potentiometer and the relationship between the surface chemistry of the membrane and its permeation properties was also studied.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.9-14
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• 2002

We propose a new algorithm for blind source separation (BSS), in which frequency-domain independent component analysis (FDICA) and time-domain ICA (TDICA) are combined to achieve a superior source-separation performance under reverberant conditions. Generally speaking, conventional TDICA fails to separate source signals under heavily reverberant conditions because of the low convergence in the iterative learning of the inverse of the mixing system. On the other hand, the separation performance of conventional FDICA also degrades significantly because the independence assumption of narrow-band signals collapses when the number of subbands increases. In the proposed method, the separated signals of FDICA are regarded as the input signals for TDICA, and we can remove the residual crosstalk components of FDICA by using TDICA. The experimental results obtained under the reverberant condition reveal that the separation performance of the proposed method is superior to that of conventional ICA-based BSS methods.