• Korean Chemical Engineering Research
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• 제48권1호
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• pp.121-127
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• 2010

본 연구의 목적은 효소법을 이용한 바이오디젤의 생산에서의 효소(lipase) 활성화를 최적화함에 있다. 효과적인 방법으로 효소를 고정하기 위해 방사선 그라프트 중합법을 이용한 부직포에 음이온 교환기인 ethanolamine과 diethylamine을 도입시켜 음이온 교환 부직포(이때 얻어진 부직포는 EtA, DEA-EtA 부직포라 함)를 합성하였다. 기존에 사용하던 다공성 중공사막의 경우 시간이 지남에 따라 막힘 현상에 따라 유속이 현저하게 줄어드는 점을 보완하고자 기공(pore size)이 $300{\mu}m$인 부직포를 선택하였다. 이 부직포에 음이온 교환기가 도입된 EtA, DEA-EtA 부직포의 최적효소 흡착 특성과 효소 활성도에 대하여 고찰하였다. 그 결과 효소 흡착량은 EtA, DEA-EtA 부직포가 비슷하였으나(EtA non-woven fabric: 15.69 mg/g, DEA-EtA non-woven fabric: 14.45 mg/g) 기름을 투과시킨 결과 효소 활성화는 DEA-EtA 부직포가 EtA 부직포에 비해 현저히 떨어짐(EtA non-woven fabric: $3.50mol/h{\cdot}kg$, DEA-EtA non-woven fabric: $0.38mol/h{\cdot}kg$)을 알 수 있었다. 이 음이온교환기를 이용해 효율적인 바이오디젤 생산을 위한 온도, 효소고정량, 기름과 알코올과의 관계 등의 최적의 조건을 도출하였다.

• Macromolecular Research
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• 제13권1호
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• pp.73-79
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• 2005

Poly(L-lactic acid-co-succinic acid-co-l,4-butane diol) (PLASB) was synthesized by direct condensation copolymerization of L-lactic acid (LA), succinic acid (SA), and 1,4-butanediol (BD) in the bulk using titanium(IV) butoxide as a catalyst. The weight-average molecular weight ofPLASB was $2.1{\times}10^{5}$ when the contents of SA and BD were each 0.5 mol/100 mol of LA. Electrospinning was used to fabricate porous membranes from this newly synthesized bioabsorbable PLASB dissolved in mixed solvents of methylene chloride and dimethylformamide. Scanning electron microscopy (SEM) images indicated that the fiber diameters and nanostructured morphologies of the electrospun membranes depended on the processing parameters, such as the solvent ratioand the polymer concentration. By adjusting both the solvent mixture ratio and the polymer concentration, we could fabricate uniform nanofiber non-woven membranes. Cell proliferation on the electrospun porous PLASB membranes was evaluated using mouse fibroblast cells; we compare these results with those of the cell responses on bulk PLASB films.

• Bulletin of the Korean Chemical Society
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• 제35권6호
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• pp.1901-1903
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• 2014

• Bulletin of the Korean Chemical Society
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• 제32권2호
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• pp.605-608
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• 2011

Hybrid composite membranes were prepared by coating poly(ethylene oxide) and $SiO_2$ particles onto the porous polypropylene nonwoven matrix. Gel polymer electrolytes prepared by soaking the hybrid composite membranes in an organic electrolyte solution exhibited ionic conductivities higher than $1.1{\times}10^{-3}Scm^{-1}$ at room temperature. Dyesensitized solar cell (DSSC) employing the hybrid composite membrane with PEO and 10 wt % $SiO_2$ exhibited an open circuit voltage of 0.77 V and a short circuit current of 10.78 $mAcm^{-2}$ at an incident light intensity of 100 $mWcm^{-2}$, yielding a conversion efficiency of 5.2%. DSSC employing the hybrid composite membrane showed more stable photovoltaic performance than that of the DSSC assembled with liquid electrolyte.

• Membrane and Water Treatment
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• 제8권3호
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• pp.225-244
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• 2017

A novel thin-film nanocomposite (TFN) reverse osmosis (RO)/non-woven fabric (NWF) membrane was prepared by adding zinc oxide (ZnO) nanospheres ($30{\pm}10nm$) during the interfacial polymerization process of m-phenylenediamine (MPD) and trimesoyl chloride (TMC) on self-made polysulfone (PSF) membrane/polyester (PET) non-woven fabric support. The improved performance of TFN RO membrane was verified in terms of water contact angle (WCA), water flux, salt rejection, antifouling properties and chlorine resistance. The results showed that the WCA value of TFN RO surface had a continuous decrease with the increasing of ZnO content in MPD aqueous solution. The water flux of composite TFN RO membranes acquired a remarkable increase with a stable high solute rejection (94.5 %) in $1g{\cdot}L^{-1}$ NaCl aqueous solution under the optimized addition amount of ZnO (1 wt%). The continuous testing of membrane separation performance after the immersion in sodium hypochlorite solution indicated that the introduction of ZnO nanospheres also dramatically enhanced the antifouling properties and the chlorine resistance of composite RO membranes.

• Journal of Periodontal and Implant Science
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• 제35권4호
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• pp.1019-1037
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• 2005

The major goals of periodontal therapy are the functional regeneration of periodontal supporting structures already destructed by periodontal disease as well as the reduction of signs and symptoms of progressive periodontal disease. There have been many efforts to develop materials and therapeutic methods to promote periodontal wound healing. There have been increasing interest on the chitosan made by chtin. Chitosan is a derivative of chitin made by deacetylation of side chains. Chitosan has been widely studied as bone substitution and membrane material in periodontology. Many experiments using chitosan in various animal models have proven its beneficial effects. Tetracycline has been considered for use in the treatment of chronic periodontal disease and gingivitis. The aim of this study is to evlauate the osteogenesis of tetracycline blended chitosan membranes on the calvarial critical size defect in Sprague Dawley rats. An 8mm surgical defect was produced with a trephine bur in the area of the midsagittal suture. The rats were divided into five groups: Untreated control group versus four experimental group. Four types of membranes were made and comparative study was been done. Two types of non-woven membranes were made by immersing non-woven chitosan into either the tetracycline solution or chitosan-tetracycline solution. Other two types of sponge membranes were fabricated by immersing chitosan sponge into the tetracycline solution, and subsequent freeze-drying. The animals were sacrificed at 2 and 8 weeks after surgical procedure. The specimens were examined by histologic analyses. The results are as follows: 1. Clinically the use of tetracycline blended chitosan membrane showed great healing capacity. 2. The new bone formations of all the experimental group, non-woven and sponge type membranes were greater than those of control group. But, there was no significant difference between the experimental groups. 3. Resorption of chitosan membranes were not shown in any groups at 2 weeks and 8 weeks. These results suggest that the use of tetracycline blended chitosan membrane on the calvarial defects in rats has significant effect on the regeneration of bone tissue in itself. And it implicate that tetracycline blended chitosan membrane might be useful for guided tissue regeneration.

• 공업화학
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• 제26권3호
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• pp.326-330
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• 2015

고분자 막은 다양한 응용분야에 적용되고 있다. 기존에 고분자 막은 옥외환경에 노출되지 않는 형태로 적용되어 왔으나 최근 대기환경 측정용도, 해수에서 유용금속 추출용 등의 옥외에 적용되는 고분자 막 시스템들이 보고되고 있다. 이에 옥외환경에서의 고분자 막의 특성 연구가 필요하게 되었으며 이러한 측면에서 촉진 자외선 노출 실험 및 이에 대한 영향 연구는 고분자 막의 내후성을 예측할 수 있는 정보를 제공할 수 있다. 본 연구에서는 폴리설폰 비대칭성 막과 폴리프로필렌 부직포 형태의 막에 대해 촉진 자외선 노출을 실시하고 이에 대한 열적, 기계적 특성, 몰폴로지, 그리고 색차변화 특성에 대한 영향을 보고한다. 실험 결과를 통해서 고분자 막의 자외선 노출에 대한 효과는 막 제조시 사용한 고분자 종류 뿐 만 아니라 막의 형태에도 영향을 받는다는 것을 확인하였다. 본 연구는 옥외용도에 적용하는 고분자막에 대한 중요한 정보를 제공할 수 있을 것으로 기대한다.

• Communications for Statistical Applications and Methods
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• 제18권3호
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• pp.301-317
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• 2011

Statistical and probabilistic behaviors of fibers forming fiber webs of all kinds are of great significance in the determination of the uniformity and physical properties of the webs commonly found in many industrial products such as filters, membranes and non-woven fabrics. However, in studying the spatial geometry of the webs the observations must be theoretically as well as experimentally confined within a specified unit area. This paper provides a general theory and framework for computer simulation for quantifying the fiber segments bounded by the unit area in consideration of the "edge effects" resulting from the truncated length segments within the boundary. The probability density function and the first and second moments of the length segments found within the counting region were derived by properly defining the seeding region and counting region.

• 대한의용생체공학회:의공학회지
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• 제44권6호
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• pp.465-475
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• 2023

In this study, we demonstrated a silica nanofibrous membrane based on the electrospinning process and evaluated its DNA isolation and purification performance in PCR pretreatment. Generally, silica membranes made of non-woven fabric are used for PCR pretreatment, but this study aimed to improve the efficiency of the pretreatment process by developing a nanofiber-type silica membrane with high specific surface area and porosity. In order to manufacture a nanofiber-shaped silica film while maintaining the original physical properties of silica, nanofiber membranes produced by adding various concentrations of PEO (5 wt%, 8 wt%, and 10 wt%) to silica prepared by the sol-gel method were compared. In terms of nanofiber membrane production, the higher the PEO concentration, the more effective it was in producing nanofiber membranes. The produced silica nanofiber membrane was inserted to a pretreatment device used in commercial PCR equipment, and the pretreatment performance was compared and verified using Salmonella bacteria. When Salmonella was used, samples containing 5 wt% PEO showed superior PCR efficiency compared to samples containing 8 wt% and 10 wt% PEO. These results show that adding 5 wt% of PEO can effectively improve DNA purification and separation by producing a nanofiber-shaped silica film while maintaining the physical properties of silica. We expect that this study will contribute to the development of effective PCR pretreatment technology essential for various molecular biology applications.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3348-3354
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• 2011

Oleanolic acid (OA) as template molecule, polyamide-6 (PA6) as basement membrane and poly(styrene-comaleic acid) (PSMA) were used to prepare PA6/PSMA-OA molecularly imprinted composite membranes by phase inversion method in supercritical $CO_2$ ($ScCO_2$). The template molecule (OA), [poly(styrene-co-maleic anhydride) (PSMAH), PSMA, molecularly imprinted membranes (MIMs) imprinting OA and MIMs after elution were all characterized by Fourier transform infrared spectroscopy (FTIR). The conditions that were the mass ratio between PSMA and OA from 3:1 to 8:1, temperature of $ScCO_2$ from $35^{\circ}C$ to $50^{\circ}C$ and pressure of $ScCO_2$ 12 MPa to 17 MPa were studied. It was obtained the largest adsorption rate and purity of OA after adsorption of the resultant MIMs, 50.41% and 96.15% respectively. After using PA6 film and non-woven fabrics as basement membrane respectively, it was found that smaller aperture of PA6 was used as basement membrane, a higher adsorption rate and a higher purity of OA after adsorption of the MIMs were obtained, and so were the stability and reproducibility of the resultant MIMs. After template molecules being removed, the MIMs had effective selectivity hydrogen bonding to separately bind in the binary components to the template molecules-oleanolic acid.