• Membrane Journal
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• v.17 no.2
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• pp.81-92
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• 2007

Membrane-based separation processes are receiving increasing attention in the scientific community and industry since they provide a desirable alternative to processes that are not easy to achieve by conventional separation technologies. In particular, gas separation using polymeric membranes have annually grown so fast owing to advantages such as easy installation, no moving parts, small footprint and low energy process. The key element is definitely a polymer membrane exhibiting high permeability and high selectivity to compete with other gas separation technologies. Current polymer membranes used for commercial gas separation are a family of hydrocarbon polymers for hydrogen separation, air separation and carbon dioxide separation from natural gas sweetening. Relatively, gas or vapor separation properties of fluoropolymers are not known so much as compared with those of hydrocarbon polymers. Accordingly, in this study, membranes prepared from amorphous perfluoropolymers are of particular interest because of the unique properties of these polymers. The advantages offered by these amorphous perfluoropolymers for use in gas and vapor separation will be discussed. In addition, membrane properties and separation performance will be compared with other membranes available on the market.

• Membrane Journal
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• v.22 no.2
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• pp.77-94
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• 2012

Amorphous ceramic membranes have been developed for gas phase separation and liquid phase separation (water treatment, wastewater treatment and separation of organic solvent or compounds) because of their thermal stability and solvent resistance. In this paper, ceramic membranes were categorized by membrane pore size and materials, and summarized for hydrogen separation, carbon dioxide separation, membrane reactor, pervaporation and water treatment with membrane structure and properties.

• Journal of the Korean Society of Visualization
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• v.17 no.3
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• pp.46-51
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• 2019

Rotor wake interaction must be considered to understand the quadrotor flight, and the rotor separation distance is an important parameter that affects the rotor wake interaction. In this study, the wake characteristics were investigated with varying the rotor separation distance. The velocity field in the rotor wake was measured using digital PIV for hovering mode at Re = 34,000, and the wake boundaries from the inner and outer rotor tips were quantitatively compared with varying the rotor separation distance. The symmetric rotor-tip vortex shedding about the rotor axis was found at a large rotor separation distance. However, the wake boundary became more asymmetric about the rotor axis with decreasing the rotor separation distance. At the minimum rotor separation distance, in particular, a faster vortex decay was observed due to a strong vortex interaction between adjacent rotors.

• Korean Journal of Child Studies
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• v.37 no.1
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• pp.17-36
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• 2016

Objective: Taking note of the fact that North Korean refugee children experience frequent separation from their mothers and long-term maternal deprivation during their childhood, this study examined the relationship between children's separation experiences and attachment. Methods: A total of 37 children aged from 5 to 9 were assessed on their attachment using the Separation Anxiety Test, and their mothers reported on their child's separation experiences. Results and Conclusion: The major findings of this study were as follows: first, the result of evaluating their attachment pattern showed North Korean refugee children had a high level of insecure attachment with a high tendency for avoidant attachment. This avoidant attachment tendency is probably due to growing up in a repressed emotional environment by frequently experiencing maternal separation in North Korea, China, and even after settling down in South Korea. Second, children's secure attachment level was higher if they did not experience separation from their mother, if their mother had a high level of education in South Korea, or if they lived with a big family.

• Resources Recycling
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• v.16 no.4
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• pp.47-60
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• 2007

Plastic supply and recycling are increasingly becoming matters of social concern. In our country, Extended Producer Responsibility(EPR) system has been adopted in 2003 to expand recycle and reuse of waste resources at producer side, and due to expansion of the EPR system, amount of the mixed plastic waste generation has been drastically increased. Plastic-plastic separation is most fundamental technique to achieve effective plastic recycling. This paper reviews recent developments in plastic-plastic separation techniques and describe future tasks. The mechanisms of each separation which contain gravity separation, electrostatic separation, flotation, and separation of automotive shredder residue are described, and commercial scale and lab-scale results are introduced.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.1 s.232
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• pp.53-58
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• 2005

We present a high-throughput continuous cell separation chip using hydrodynamic dielectrophoresis (DEP) process. The continuous cell separation chip uses three planar electrodes in a separation channel, where the positive DEP cells are moved away from the central streamline while the negative DEP cells remain in the central streamline. In the experimental study, we use the mixture of viable (live) and nonviable (dead) yeast cells in order to obtain the continuous cell separation conditions. For the conditions of the electric fields frequency of 5MHz and the medium conductivity of $5{\mu}S/cm$, the fabricated chip performs a continuous separation of the yeast cell mixture at the varying flow-rate in the range of $0.1{\sim}{\mu{\ell}/min$.; thereby, resulting in the purity ranges of $95.9{\sim}97.3\%\;and\;64.5{\sim}74.3\%$ respectively for the viable and nonviable yeast cells. present chip demonstrates the constant cell separation performance for varying mixture flow-rates.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.95-98
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• 2004

The present work has been developed the study of interpretation of separation behavior in gas expansion separation(GES) bolt which has the separation characteristic without fragmentation and minimum pyre-shock during the operation of the explosive bolt. In order to obtain the performance of minimum pyro-shock, the present work used non-compressive material instead of separation explosives. The use of the interpretation processor could be extensively helped to design the shape and the amount of explosives in the explosive bolt having complex geometry, and to analyse the separation behavior during the operation. It is also proved that the GES bolt is the most suitable the separation system necessary to minimum pyro-shock and non fragmentation compare to others.

• Progress in Superconductivity and Cryogenics
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• v.24 no.3
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• pp.19-23
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• 2022

We have been developing a magnetic separation device that can be used in low magnetic fields for paramagnetic materials. Magnetic separation of paramagnetic particles with a small particle size is desired for volume reduction of contaminated soil in Fukushima or separation of iron scale from water supply system in power plants. However, the implementation of the system has been difficult due to the needed magnetic fields is high for paramagnetic materials. This is because there was a problem in installing such a magnet in the site. Therefore, we have developed a magnetic separation system that combines a selection tube and magnetic separation that can separate small sized paramagnetic particles in a low magnetic field. The selection tube is a technique for classifying the suspended particles by utilizing the phenomenon that the suspended particles come to rest when the gravity acting on the particles and the drag force are balanced when the suspension is flowed upward. In the balanced condition, they can be captured with even small magnetic forces. In this study, we calculated the particle size of paramagnetic particles trapped in a selection tube in a high gradient magnetic field. As a result, the combination of the selection tube and HGMS (High Gradient Magnetic Separation-system) can separate small sized paramagnetic particles under low magnetic field with high efficiency, and this paper shows its potential application.

• Earthquakes and Structures
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• v.26 no.4
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• pp.285-297
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• 2024

Due to the imbalanced vibration of the adjacent buildings, the pounding phenomenon occurs as a result of an insufficient gap between them. Providing enough gap between adjacent structures is the most efficient approach to preventing the pounding effect. This paper calculated the required separation gaps between adjacent buildings, including two, four, eight, twelve and twenty stories steel moment-resisting frames, and investigated their related influencing parameters such as time periods, damping ratios, and the number of bays. The linear and nonlinear dynamic time-history analyses under real seismic event records were conducted to calculate the required separation gaps by obtaining relative displacement and velocity functions of two adjacent frames. The results showed that the required separation gap increased when the time periods of adjacent frames were not the same. The resulting separation gaps values of linear and nonlinear analyses were similar only for two and four stories frames. In other frames, the resulting separation gap values of linear analyses surpassed the corresponding nonlinear analyses. Although increasing the damping ratios in adjacent frames causes a decrease in the required separation gaps, the number of bays had no significant effect on them.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.11
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• pp.25-32
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• 2007

In this paper, we propose the Group Separation Algorithm for RFID Tag Anti-Collision. We study the RFID Tag anti-collision technique of ALOHA and the anti-collision algorithm of binary search. The existing technique is several problems; the transmitted data rate included of data, the recognition time and energy efficiency. For distinction of all tags, the Group Separation algorithm identify each Tag_ID bit#s sum of bit #1#. In other words, Group Separation algorithm had standard of selection by collision table, the algorithm can reduce unnecessary number of search even than the exisiting algorithm. The Group Separation algorithm had performance test that criterions were reader#s number of repetition and number of transmitted bits for understanding tag. We showed the good performance of Group Separation algorithm better than exisiting algorithm.