• Proceedings of the KSME Conference
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• 2001.06a
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• pp.547-552
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• 2001

An intensity-based optical fiber vibration sensor is applied to detect and evaluate damages and fiber failure of composites. The optical fiber vibration sensor is constructed by placing two cleaved fiber end, one of which is cantilevered in a hollow glass tube. The movement of the cantilevered section lags behind the rest of the sensor in response to an applied vibration and the amount of light coupled between the two fibers is thereby modulated. Vibration characteristics of the optical fiber vibration sensor are investigated. Surface mounted optical fiber vibration sensor is used in tensile and indentation test. Experimental results show that the optical fiber sensor can detect damages and fiber failure of composites correctly.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.03a
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• pp.1-21
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• 1994

There are growing needs to produce relatively high purity (99.0% or higher) oxygen at low cost. For small scale production, both pressure swing adsorption (PSA) and membrane process are competitve and less expensive or more convient than well known crygenic fractionation technology. A continuous membrane colume (CMC) combined with a PSA oxygen generator can be employed to produce high purity oxygen continuosly. The oxygen-enriched gas generated by a PSA unit, with a concentration of 93-94%, is fed to the CMC that consists of three modules of poly(imide) hollow fibers. Several experiments were conducted by varying parameters, such feed flow rate, transmenbrane pressure drop, stage cut, and feed location in order to obtain a high oxygen concentration above 99.0%. A two-series unit mode was also employed with CMC operation to optimize the given membrane area.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.04b
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• pp.59-61
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• 1997

최근 신소재에 관한 연구는 첨단기술 발전에 주요한 역할을 하고 있음은 주지의 사실이며, 특히 다목적, 다기능 고분자는 여러 분야에 활용되므로 이에 관한 집중적인 연구가 활발히 진행되고 있다. 고분자는 보통 화합물과는 달리 여러 분자량의 중합체가 분포되어 있으므로 물리-화학적 특성을 알아내기가 힘들뿐만 아니라, 이러한 고분자 물질의 분자량, 분자량 분포 등의 정보가 폭 넓게 파악되어야만 그 물질의 정확한 활용과 소재 개발이 가능하다. 특히 protein 등과 같은 생체 고분자들은 유전, 특정 반응에 작용하는 효소, 호르몬 등 수많은 연구가 진행 중에 있으나 그 분리.정제 과정은 상당히 어려우며, 경우에 따라서는 분리. 정제 과정에서 활성을 잃은 경우도 있다. 따라서 이러한 고분자들의 물성을 확인하는 과정이 최우선적으로 필요하다.

• Macromolecular Research
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• v.16 no.2
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• pp.85-102
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• 2008

The development of reliable synthetic routes to polymer nanomaterials with well-defined size and morphology is a critical research topic in contemporary materials science. The ability to generate nanometer-sized polymer materials can offer unprecedented, interesting insights into the physical and chemical properties of the corresponding materials. In addition, control over shape and geometry of polymer nanoparticles affords versatile polymer nanostructures, encompassing nanospheres, core-shell nanoparticles, hollow nanoparticles, nanorods/fibers, nanotubes, and nanoporous materials. This review summarizes a diverse range of synthetic methods (broadly, hard template synthesis, soft template synthesis, and template-free synthesis) for fabricating polymer nanomaterials. The basic concepts and significant issues with respect to the synthetic strategies and tools are briefly introduced, and the examples of some of the outstanding research are highlighted. Our aim is to present a comprehensive review of research activities that concentrate on fabrication of various kinds of polymer nanoparticles.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.333-346
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• 2018

This study presents a mathematical modeling approach for developing models based on non-ideal conditions related to the membrane structure including porous supporting layer and deformation under pressure. Comparison of the findings with experimental data reveal the importance of considering the resistance in porous supporting layer though the effect of concentration polarization in the permeate stream could be neglected. Investigations on deformation of fibers under pressure ascertain that at larger fiber inner radius to outer radius ratios, increasing driving force may lead to an initial increase in permeability. After that, the effects of deformation dominates and thus permeability may be decreased.

• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.1036-1042
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• 1998

It was investigated that the extraction of Cr(VI) from aqueous solution into the organic TDA and the stripping(back extraction) of Cr(VI) from the Cr(VI)-TDA complex into NaOH aqueous solution by hydrophobic hollow fiber membrane. It was found that the mass transfer rates of stripping process were smaller than those of the extraction process. This result was expected that membrane resistance, neglected in the extraction process, acts on the stripping process when organic phase flow in the tube side of the hydrophobic membrane. Hollow fiber modules were made by potting the desired number(60, 100, 150, 300fibers). We also examined the effect of flow rates of aqueous and organic phase on the mass transfer rate in the membrane modules. From these experiments, we identified for the extraction process by using hydrophobic membrane, the effect of flow rate of aqueous phase on the mass transfer rate was significant, but that of organic phase was negligible one. In the stripping process, however, mass transfer rate depend neither flow rate of aqueous(stripping solution) phase nor that of organic(Cr-TDA complex) phase.

• Bulletin of the Korean Chemical Society
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• v.25 no.1
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• pp.63-68
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• 2004

Sugar-based gelator p-dodecanoyl-aminophenyl- ${\beta}$-D-aldopyranosides (1-3) have been shown to self-assemble in the presence of p-aminophenyl aldopyranosides. The hydrogel 1+4 showed the double-helical structure with 3-25 nm outer diameters, which is quite different from that of 1. The gel 2+5 revealed twisted ribbon structure with 30-50 nm in widths and a few micrometers of length whereas the gel 3+4 revealed the single and the bundled fiber structures. The difference in these gel supramolecular structures has successfully been transcribed into silica structures by sol-gel polymerization of tetraethoxysilane (TEOS), resulting in the doublehelical, the twisted-ribbon, the single and the multiple (lotus-shaped) hollow fiber structures. These results indicate that novel silica structures can be created by transcription of various superstructures formed in binary gels through the hydrogen-bonding interaction, and the amino group of the p-aminophenyl aldopyranosides acts as an efficient driving force to create novel silica nanotubes. Furthermore, electron energy-loss spectroscopy (ELLS) provided strong evidence for the inner hollow structure of the double-helical silica nanotube. This is a novel and successful example that a variety of new silica structures can be created using a library of carbohydrate gel fibers as their templates.

• Journal of Physiology & Pathology in Korean Medicine
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• v.33 no.1
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• pp.25-30
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• 2019

This study was aimed to examine the synergetic effects of photochemopreventive external agents composed of inorganic ZnO and esculetin. Zinc oxide (ZnO) is widely used in sunblocks because of its excellent biostability and little toxicity. Esculetin derived from Citrus Peel has an anti-oxidative effect. We made the hollow-shaped ZnO microsphere (MS), soaked it with esculetin (EZnO). We used SKH-1 mice to measure the photodamaging effects of UVB. The mice were divided into five groups as follows; UVB nontreated group (N), vehicle (C), esculetin (E), ZnO MS (ZnO), esculetin + ZnO MS(EZno) group. Each group of samples was topically applied to the dorsal skins before the UVB irradiation. The changes of collagen fibers in the skin tissues were observed by H & E staining and Van Gieson staining. The expression of mast cells in skin tissue was observed by immunohistochemical staining of tryptase present in the mast cell granules. Expression of inflammatory cytokines such as TNF-${\alpha}$, IL-$1{\beta}$, and MMP-9, which plays an essential role in wrinkle formation, was measured by RT-PCR. Interestingly, the composition of collagen fibers was better in the EZnO applied group than in the E or ZnO group. Moreover, mast cell expression and the expression of TNF-${\alpha}$, IL-$1{\beta}$, and MMP-9 mRNA were markedly suppressed in the EZnO group, indicating that the synergetic effects of esculetin and ZnO were excellent.

• Membrane Journal
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• v.5 no.1
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• pp.35-43
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• 1995

For several years lots of attempts have been made to establish the liquid membrane-based techniques for separations of gas mixtures especially containing carbon dioxide. A more effective system to separate $CO_{2}$ from flue gases, a circulatory hollow-fiber membrane absorber(HFMA) consisting of absorption and desorption modules with vacuum mode, has been considered in this study. Gas-liquid mass transfer has been modeled on a membrane module with non-wetted hollow-fibers in the laminar flow regime. The influence of an absorbent flow rate on the separation performance of the circulatory HFMA can be predicted quantitatively by obtaining the $CO_{2}$ concentration profile in a tube side. The system of $CO_{2}/N_{2}$ binary gas mixture has been studied using pure water as an(inert) absorbent. As the absorbent flow rate is increased, the permeation flux(i.e., defined as permeation rate/membrane contact area) also increases. The enhanced selectivity compared to the previous results, on the other hand, shows the decreasing behavior. It has been found obviously that the permeation flux depends on the variations of pressure in gas phase of desorption module. From an accurate comparison with the results of conventional flat sheet membrane module, the advantageous permeability of this circulatory HFMA can be clearly ascertained as expected. Our efforts to the theoretical model will provide the basic analysis on the circulatory HFMA technique for a better design and process.

• Membrane Journal
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• v.12 no.1
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• pp.41-50
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• 2002

The streaming potential generated by the electrokinetic flow within electric double layer of charged microchannel is applied to determine the zeta potential of hollow-fiber membrane pore by using the general Helmholtz-Smoluchowski equation. The streaming potential is know to provide a useful real-time information on the surface property and the interaction between pore and particles in actual situations and physicochemical conditions. The influence of physicochemical parameters upon the filtration with hollow-fibers has been examined with an in-situ and simultaneously monitoring the streaming potential as well as permeate flux. In particular, the present study examined an experimental method to identify the effect of cake layer which can vary according to the axial position of a hollow-fiber and the progress of membrane fouling by measuring the position-dependent streaming potential. As the latex concentration increases, the permeate flux decreased but the streaming potential increased. The growth of cake layer has been mire developed with increasing latex concentration, however, the effect of surface charges of latexes deposited on the membrane surface leads to increase the streaming potential. With increasing ionic concentration of KCI, both the permeate flux and the streaming potential decrease. The increase of ionic concentration provides a compact cake layer due to the shrinkage of Debye length and the decreased streaming potential results from the weakened ionic flows owing to a thin diffusive double layer.