• Membrane Journal
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• v.22 no.6
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• pp.481-488
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• 2012

The anionic exchange polymer, poly(vinyl amine)(PVAm), was coated onto polyamide (PA) reverse osmosis (RO) membranes by using 'salting-out' method. The effects of the fouling phenomena for these PVAm coated membranes were investigated using the model foulants, bovine serum albumin (BSA), humic acid (HA), and sodium alginate (SA). The surface coating and the fouling phenomena were observed by the scanning electron microscopy. And the flux was measured for each 100 ppm of above foulant aqueous solution at the operating pressure, 2, 4, 8 bar. The PVAm-coated PA membranes showed somewhat fouling improvements and the fouling reduction was shown in the order of HA > SA > BSA, particularly HA case was distinct.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.22 no.1
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• pp.22-32
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• 2000

Purpose : Histopathologic observation was performed in order to determine which type of suture material is superior in microvascular anastomoses. Materials & Methods : The interrupted end to end anastomosis of the transected carotid arteries of 105 Sprague-Dawley rats, weighing 180 to 200g, were performed using 9-0 polypropylene ($Prolene^{TM}$, Ethicon, U.K.), 9-0 polyglactin 910 monofilament($Vicryl^{TM}$, Ethicon, U.K.), and 9-0 polyamide($Ethilon^{TM}$, Ethicon, U.K.) under intramuscular Ketamine and Xylazine anesthesia(5mg/100g). In all cases, 10 to 12 sutures were placed to complete the anastomoses. The specimens were obtained at 1, 2, 3 days, and 1, 2, 4 and 6 weeks after the surgery and prepared with H&E and Van-Gieson stains and investigated the histologic changes in anastomotic sites under light microscope. The histologic changes we were concerned about were followings- thrombus formation, intimal edema, infiltration of inflammatory cells in media and adventitia, proliferation of endothelial cells and subintimal hyperplasia. Results : 1. All of the anastomosed arteries were patent when they were exposed for examination. 2. Thrombus formation and intimal edema were most severe in Vicryl group, followed by Ethilon, Prolene group in order. 3. The inflammatory cells infiltrated to the media and the adventitia most severely in Ethilon group, followed by Vicryl, Prolene group in order. 4. There was little difference in proliferation of endothelial cells in each group. 5. Subintimal hyperplasia was greater in Vicryl group than the others, but there was no significant difference between the Prolene and Ethilon groups. Conclusions : On the basis of these observations, we could conclude that Prolene may be the better suture material for microvascular anastomoses regarding the tissue responses than Ethilon and Vicryl.

• Membrane and Water Treatment
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• v.11 no.5
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• pp.323-331
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• 2020

With the increasing demand on reverse osmosis (RO) membranes for water purification worldwide, the number of disposed membrane elements is expected to increase accordingly. Thus, recycling and reuse of end-of-life RO membranes should be a global environmental action. In this work, we aim to reuse the spent RO membrane for nanofiltration (NF) and ultrafiltration (UF) process by subjecting the spent membrane to solvent and oxidizing solution treatment, respectively. Our results showed that solvent-treated RO membrane could perform as good as commercial NF membrane by achieving similar separation efficiencies, but with reduced water permeability due to membrane surface fouling. By degrading the polyamide layer of RO membrane, the transformed membrane could achieve high water permeability (85.6 L/㎡.h.bar) and excellent rejection against macromolecules (at least 87.4%), suggesting its reuse potential as UF membrane. More importantly, our findings showed that in-situ transformation on the spent RO membrane using solvent and oxidizing solution could be safely conducted as the properties of the entire spiral wound element did not show significant changes upon prolonged exposure of these two solutions. Our findings are important to open up new possibilities for the discarded RO membranes for reuse in NF and UF process, prolonging the lifespan of spent membranes and promoting the sustainability of the membrane process.

• Korean Journal of Materials Research
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• v.6 no.8
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• pp.786-795
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• 1996

The fiber reinforced thermoplastics(FRTP) were prepared with polypropylene fiber(PP) as matrix and polyvinyl alchol(VF), aramid(KF) or polyamide fiber(PAF) as the reinforcing materials using the integrated fiber mixing apparatus. The reinforced thermoplastic sheets were prepared by com¬pression molding and their morphology, rheological and mechanical properties were characterized. In the morphological properties of composites, the wettability of the reinforced thermoplastics were decreased in proportion to the content of fibers. At low angular frequency, the viscosity of PAF /PP and VF/PP composite was increased with the content of reinforced fiber. However at high frequency the viscosity of composite reinforced with 5~20wt% fiber, was shown the reduced values which approaches that of the neat matrix. The mechanical properties of the composite were changed with the content of reinforecd fiber, and VF/PP and KF/PP composite had better properties than PAF/PP system.

• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.782-788
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• 2018

Submicron copper-silver core-shell (Cu@Ag) particles were synthesized using the sonochemical combined transmetallation reaction and the application to printed electronics as a low cost conductive paste was evaluated. $Cu_2O$ of the $Cu_2O/Cu$ composite used as a core in the reaction for the synthesis of core-shell was sonochemically reduced to Cu, and Cu atoms functioned as a reducer for silver ions in transmetallation to achieve the copper-silver core-shell structure. The characterization of submicron particles by TEM-EDS and TG-DSC confirmed the core-shell structure. Conductive pastes in which 70 wt% Cu@Ag was dispersed in solvents were prepared using a binder and wetting agents, and coated on the polyamide film using a screen-printing method. Printed paste films containing synthesized Cu@Ag particles with 8 at% and 16 at% Ag exhibited low resistivity of 96.2 and $38.4{\mu}{\Omega}cm$ after sintering at $180^{\circ}C$ in air, respectively.

• Archives of Plastic Surgery
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• v.41 no.6
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• pp.638-646
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• 2014

Background The combination of polycaprolactone and hyaluronic acid creates an ideal environment for wound healing. Hyaluronic acid maintains a moist wound environment and accelerates the in-growth of granulation tissue. Polycaprolactone has excellent mechanical strength, limits inflammation and is biocompatible. This study evaluates the safety and efficacy of bio-conjugated polycaprolactone membranes (BPM) as a wound dressing. Methods 16 New Zealand white rabbits were sedated and local anaesthesia was administered. Two $3.0{\times}3.0cm$ full-thickness wounds were created on the dorsum of each rabbit, between the lowest rib and the pelvic bone. The wounds were dressed with either BPM (n=12) or Mepitel (n=12) (control), a polyamide-silicon wound dressing. These were evaluated macroscopically on the 7th, 14th, 21st, and 28th postoperative days for granulation, re-epithelialization, infection, and wound size, and histologically for epidermal and dermal regeneration. Results Both groups showed a comparable extent of granulation and re-epithelialization. No signs of infection were observed. There was no significant difference (P>0.05) in wound size between the two groups. BPM (n=6): $8.33cm^2$, $4.90cm^2$, $3.12cm^2$, $1.84cm^2$; Mepitel (n=6): $10.29cm^2$, $5.53cm^2$, $3.63cm^2$, $2.02cm^2$; at the 7th, 14th, 21st, and 28th postoperative days. The extents of epidermal and dermal regeneration were comparable between the two groups. Conclusions BPM is comparable to Mepitel as a safe and efficacious wound dressing.

• Korean Journal of Construction Engineering and Management
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• v.21 no.6
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• pp.95-102
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• 2020

The number of use cases in machinery, aviation, and other industries that manufacture precise parts is increasing, and the construction industry is also increasingly using 3D printing technology. Although various materials for 3D printing are currently being developed and utilized, 3D printing manufacturing has a problem that the mechanical properties of the product may change when compared with conventional manufacturing methods such as injection and molding. This paper verifies the effect of the printing orientation on the mechanical properties of the product in the manufacture of PA12 material and providing basic data on the practical use of the materials as building subsidiary materials and structural materials. The results of the experiment showed that the product printed in the orientation of 0° showed the lowest overall strength and elongation rate, and the product printed in the orientation of 45° showed the highest figure. Overall, tensile strength and yield strength increased between 0° and 45°, and tended to decrease somewhat at 45° to 90°.

• Environmental Engineering Research
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• v.22 no.3
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• pp.329-338
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• 2017

Nanofiltration (NF) technology is a membrane-based separation process, which has been pervasively used as the high-effective technology for drinking water treatment. In this study, a kind of composite polyamide NF thin film is selected to investigate the removal efficiencies and mechanisms of 14 trace drugs, which are commonly and frequently detected in the drinking water. The results show that the removal efficiencies of most drugs are quite high, indicating the NF is an effective technology to improve the quality of drinking water. The removal efficiencies of carbamazepine, acetaminophen, estradiol, antipyrine and isopropyl-antipyrine in ultrapure water are $78.8{\pm}0.8%$, $16.4{\pm}0.5%$, $65.4{\pm}1.8%$, $71.1{\pm}1.5%$ and $89.8{\pm}0.38%$, respectively. Their rejection rates increase with the increasing of their three-dimensional sizes, which indicates that the steric exclusion plays a significant role in removal of these five drugs. The adsorption of estradiol with the strongest hydrophobicity has been studied, which indicates that adsorption is not negligible in terms of removing this kind of hydrophobic neutral drugs by NF technology. The removal efficiencies of indomethacin, diclofenac, naproxen, ketoprofen, ibuprofen, clofibric acid, sulfamethoxazole, amoxicillin and bezafibrate in ultrapure water are $81{\pm}0.3%$, $86.3{\pm}0.5%$, $85.7{\pm}0.4%$, $93.3{\pm}0.3%$, $86.6{\pm}2.5%$, $90.6{\pm}0.4%$, $59.7{\pm}1.7%$, $80.3{\pm}1.4%$ and $80{\pm}0.5%$, respectively. For these nine drugs, their rejection rates are better than the above five drugs because they are negatively charged in ultrapure water. Meanwhile, the membrane surface presents the negative charge. Therefore, both electrostatic repulsion and steric exclusion are indispensable in removing these negatively charged drugs. This study provides helpful and scientific support of a highly effective water treatment method for removing drugs pollutants from drinking water.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.527-533
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• 2017

As the clothing industry has advanced, dyeing technologies using various dyes have been developed. In recent years, interest in natural pigments has been increasing because of the negative impact of synthetic pigment on human health; therefore, development and application of microbial pigments is demanded. In this study, the dyeing effects on multifiber fabrics and biological activity were assessed using violet natural pigment from the marine bacterium, Microbulbifer sp. PPB12. The violet pigment produced by cultivation of Microbulbifer sp. PPB12 using Marine broth 2216 for 3 days was extracted using ethanol. Once dissolved in 20% ethanol, the violet pigment could be used to dye bleached cotton, diacetate, and especially polyamide. The optimal temperature, time, pH, and bath ratio under the dyeing conditions were $80^{\circ}C-90^{\circ}C$, more than 1 hour, pH 4-6, and 1:25, respectively. The mordant treatment was more suitable for color expression when $Na_2SO_4$ was used after 10 minutes of dyeing, but no significant difference was observed from untreated samples. The violet pigment also showed antibacterial activity against B. subtilis. The results of the present study indicate that the marine bacterial pigment could be an alternative for textile dyeing as a natural dye with antibacterial activity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.12
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• pp.1767-1772
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• 2009

Brined Baechu cabbages were packed with different films of high density polyethylene (HDPE), aluminium polyethylene (Al/PE), nylon polyamide (Ny/PE), low density polyethylene (LDPE) and permeability-controlled polyethylene (Mirafresh (MF), US patent No. 5972815), and then stored at 4${^{\circ}C}$ for 4 weeks. Changes in quality characteristics of pH, acidity, total bacteria counts, lactic acid bacteria counts, E. coli counts, texture and $O_2$ concentration were determined during the storage. The pH of brined Baechu cabbage packed with Mirafresh (MF) film was 6.25 after 4 weeks from initial pH of 6.80. The acidity of all brined Baechu cabbages increased, however, the increase of the cabbage in MF was the lowest. The levels of total bacteria, lactic acid bacteria and E. coli in the cabbages packed with MF were also lower than the other films. After 4 weeks, of all brined springiness Baechu cabbages decreased, but MF showed relatively high springiness. The $O_2$ concentrations by its permeation through MF were 0.35%-1.00% at 4-25${^{\circ}C}$ after 1 week. In conclusion, MF was found to be the most effective packaging film for brined Baechu cabbage to extend shelf-life.