• Journal of Korean Society of Water and Wastewater
• /
• v.12 no.2
• /
• pp.42-49
• /
• 1998

By checking the variations of the raw water quality and MLSS, the effects of the membrane materials on permeable flux and quality of the treated water were investigated in this study. Due to the stability for high variations of MLSS, tubular type membranes were selected. Polysulfone group membranes and polyamide group membranes were tested. The crossflow operation mode was adapted, because membrane fouling problems could be easily controlled by adjusting the linear velocity. Due to the high concentration of the raw water, polyamide group membranes were originally expected to achieve two times higher permeable fluxes. However, difference was only approximately $20l/m^2{\cdot}h$ at $3kgf/cm^2$. It might be resulted from the high concentration of organic materials in the effluent of the RBC process. For the quality of the treated water, polyamide group membranes were slightly less effective. It might be resulted from the fact that polysulfone group membranes had more adsorptive capacities for the organic materials. The effects of temperature on the permeable flux were found to be significant. Despite of the irregular injection of raw water, the quality of the treated water was kept stable.

• Food Science and Preservation
• /
• v.12 no.4
• /
• pp.323-328
• /
• 2005

This study were investigated to analyzed an optimum preparation condition of coating film and its antimicrobial activity on pathogenic and deteriorative bacteria to obtain fundamental data for development of active packaging film using antimicrobial peptide, polysine. In the preparation conditions of coating film, antimicrobial activity was depending on the concentration of polylysine and polyamide respectively, and relatively high activity was obtained in the film prepared with more than $1.0\%$ (w/v) of polylysine, $40\%$ (w/v) polyamide, and more than $50\;{\mu}m$ of film thickness. Concentration of polylysine migrated from coated film to distilled water was reached at the maximum concentration, about 20 ppm after 3 days and in equilibrium after 7 days of soaking in sterilized water. An antimicrobial activity of coated film showed bactericidal effect of about $10^5\;CFU/mL$ comparing with the control against Bacillus cereus having $4.8{\times}10^5\;CFU/mL$ of initial viable cell numbers, and of about $10^2\;CFU/mL$ comparing with the control against Klebsiella pneumoniae having $6.8{\times}10^5\;CFU/mL$ of initial viable cell numbers. Consequently, it was revealed that polylysine coating film has a potential of applicable possibility as antimicrobial packaging film.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1997.11a
• /
• pp.120-123
• /
• 1997

In this paper, we deal with the effect on magnetic properties when Nd is added to Sr ferrite bonded magnet. First, we choose SrO$_{n}$.Fe$_2$O$_3$(n=5.9), which is nonstoichiomatric composition, as specimen ferrite. Then, we add 5wt% polyvinyl alcohol and calcinate at 12$25^{\circ}C$ under $N_2$ environment for carbon coating on chemical compound specimen. After that we obtain 1.2${\mu}{\textrm}{m}$ single domain powder through grinding process for 18 hours. The single domain Sr ferrite Powder is well mixed with silage coupling and calcium stearate of 1wt% Then, it is kneaded by using polyamide12 as a binder and is pelleted. After adding Nd-Fe-B powder to the pelleted specimen, we injection-mould it under magnetic field by using anisotropic mould. Especially, when we add l3wt% Nd-Fe-B powder to the polyamide12, we obtain excellent magnetic propertiecs which are $_{B}$H$_{C}$=2.65KOe, Br=3.16KG and (BH)$_{max}$=2.61MGOeOeOeOeOe

• Applied Chemistry for Engineering
• /
• v.7 no.1
• /
• pp.194-202
• /
• 1996

Hot melt adhesive based on the polyamide resin was studied to improve the conventional hot melt adhesives such as ethylene-vinyl acetate which have inherent problems against creep and heat resistance. It was found that the terpolymer of nylons6, nylon66, and nylon12 or the nylon blend instead of nylon homopolymer was suitable base resin for hot melt adhesives, since the disruption of regularity in the polymer chains reduced the crystallinity, resulting in lower melting point and melt viscosity. Also, the rheological properties of the polyamide based hot melt adhesive could be controlled by the incorporation of terpene resin, butyl benzyl phthalate, and paraffin wax. The results of melt viscosities and tensile properties of adhesive itself indicated that the optimum adhesion properties could be obtained through the blending of CM831/843P resins with weight ratio 75/25~50/50. The adhesion between steel and steel was tested by using lap shear geometry. It was found that the surface roughness of steel affected the adhesion strength.

• Textile Coloration and Finishing
• /
• v.12 no.6
• /
• pp.353-360
• /
• 2000

In this article, arrowroot is extracted in distilled water, and its dyeing properties on wool, nylon, and silk were investigated. Also the effect of mordanting (Al, Cu, Sn, Fe and Cr compounds) on the wash fastness are measured. The wavelength of maximum absorption of the arrowroot extract appears at 250 and 300nm below pH 7, but they shifted to longer wavelength at higher pH values. It appears that the optimum condition of the dyeing of wool, nylon, and silk fabric with arrowroot extract is $60^\circ{C}$, 60 min, and pH 4.0. Mordant treatments are effective in improving wash fastness of polyamide fabrics.

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.7
• /
• pp.7-12
• /
• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2007.11a
• /
• pp.529-530
• /
• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.06a
• /
• pp.973-974
• /
• 2008

• Journal of Korean Ophthalmic Optics Society
• /
• v.18 no.4
• /
• pp.365-371
• /
• 2013

Purpose: In this study, we evaluated the physical and thermal properties of the compositions made by blending glass fiber (GF) of different contents into glass fiber polyamide-66, and investigated if the compositions applying to the glasses frame to replace the TR-90, which is polyamide-12 resin used as an injection-type spectacle frame material. Methods: To investigate the characteristics change of polyamide-66 (PA-66) compositions with the change of the content of glass fibers, we produced a composition of the content by using a twin-screw extruder. The mechanical strength of the composition production was measured and coating properties as well as cutting processability were evaluated. We evaluated the applicability of the glasses frame by comparison the results of new compositions with characterizations of traditional TR. Results: For the results of the characterization of Polyamide-66/GF composition, we found that the higher increase of content of the glass fiber, the less mold shrinkage rate, and the mechanical strength was increased. Tensile strength increased from $498kg/cm^2$ for 0 wt% of the content of the glass fibers to $849kg/cm^2$ for 30 wt% of the content of the glass fibers. As a result of a coating evaluation, the strength of coating was 4B in the GF 5wt% and 5B, which was extremely good coating characteristics, in the over than GF 5 wt%. Conclusions: In case that 30 wt% of the glass fiber was blended, the mechanical strength was greatly improved, the hardness was increased, injection temperature increased due to increase of the viscosity, and the flow mark of the product may occur. The paint coating of PA-66 blended with glass fiber was all excellent. With general evaluating physical properties and workability properties it was determined that around 10 wt% of the content of the glass fibers was possible to apply a spectacle frame.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.12
• /
• pp.2359-2362
• /
• 2007

MALDI-TOF-MS technique was applied to obtain structural and compositional information of synthetic polyamides, Nylon6 and Nylon66. Mass spectra of both the original and the hydrolyzed polyamide samples were analyzed using the self calibration method as well as the internal calibration method with the standard materials of known masses. The MALDI-TOF mass spectra of Nylon6 samples showed the presence of protonated, sodiated, and potassiated ions that were assigned to cyclic and NH2/COOH terminated linear oligomers. From the MALDI-TOF mass spectra of Nylon66 samples, the potassiated linear oligomers with three different end groups are identified as well as the cyclic oligomers, i.e., NH2/COOH terminated oligomers, NH2/NH2 terminated oligomers, and COOH/COOH terminated oligomers. Full characterization of the molecular species and end groups present in the polyamide samples has been achieved, and also the changes in mass spectral patterns after the hydrolysis of the samples are presented.