• Journal of the Korean Magnetics Society
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• v.14 no.5
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• pp.186-191
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• 2004

The variation of magnetic properties with insulating materials(glass frits, talc and polyamide) in compressed powder cores composed of Fe$\sub$73.5/Cu$_1$Nb$_3$Si$\sub$15.5/B$\sub$7/ nanocrystalline alloy powders(size: 250～850 $\mu\textrm{m}$) and 3 wt% insulators has been investigated. Larger permeability was obtained at the frequency lower than 300～400 kHz for the powder cores including ceramic insulators(glass frits and talc) as compared to the cores with polyamide, while at higher frequency than 1 MHz the permeability of the former cores decreased rapidly. Further the cores with ceramic insulators showed larger core loss and smaller peak quality factor attained at lower frequency. On the contrary, the powder cores with polyamide exhibited high stability of permeabilities up to several MHz and superior core-loss and quality-factor properties. Moreover the dc bias property was better in the wide field range for the cores having polyamide. The enhanced magnetic properties of polyamide-added cores were attributed to the more sufficient electrical insulation between magnetic particles, where the higher insulation state was considered to be obtained from the larger volume fraction of polyamide in the powder cores.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.471-476
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• 2008

The thermal and mechanical properties and morphology of epoxy/polyamide/DDS/2E4MZ-CNS reactive blends with various amounts of polyamide were investigated. The amount of polyamide was 10, 20, and 30 phr and 2 phr of catalyst was added to the blend to cure at $180^{\circ}C$ for 30 min. By adding the catalyst, 2E4MZ-CNS, to the blend, the cure reaction occurred at a lower temperature. From the SEM images, it was found that the boundary of separated-phase was unclear and the phase was co-continuous. Without the catalyst, however, the boundary of separated-phase was clear. The control of cure temperature and morphology could be achieved by using a proper catalyst and consequently the mechanical strength increased by 20% compared to the blend without the catalyst due to the strong interaction between epoxy matrix and phase-separated polyamide at the interface.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.76-85
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• 2017

In this study, to evaluate the mechanical properties of fiber-reinforced cement composites by strain rate, hydraulic rapid loading test system was developed. And compressive and tensile strength of the hooked steel fiber and polyamide fiber reinforced cement composite were evaluated. As a result, the compressive strength, strain capacity and elastic modulus were increased with increasing strain rate. The effect of compressive strength by type and volume fraction of fibers was not significant. The dynamic increase factor(DIF) of the compressive strength was higher than that of the CEB-FIP model code 2010 and showed a trend similar to that of ACI-349. The tensile strength and strain capacity were increased with increasing strain rate. The hooked steel fibers were drawn from the matrix. The tensile strength and strain capacity of hooked steel fiber reinforced cement composites were increased as the strain rate increased. The tensile strength and deformation capacity of the fiber reinforced cement composites were increased. And, hooked steel fibers were drawn from the matrix. On the other hand, because the bonding properties of polyamide fiber and matrix is large, polyamide fiber was cut-off with out pullout from matrix. The strain rate effect on the tensile properties of polyamide fiber reinforced cement composites was found to be strongly affected by the tensile strength of the fibers.

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

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.319-325
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• 2018

The use of 3D printing (Additive Manufacturing) technology has expanded from initial model production to the mass production of parts in the industrial field based on the continuous research and development of materials and process technology. As a representative polymer material for 3D printing, the polyamide-based material, which is one of the high-strength engineering plastics, is used mainly for manufacturing parts for automobiles because of its light weight and durability. In this study, the specimens were fabricated using Selective Laser Sintering, which has excellent mechanical properties, and the flexural characteristics were analyzed according to the temperature of the two types of polyamide 12 and glass bead reinforced PA12 materials. The test specimens were prepared in the directions of $0^{\circ}$, $45^{\circ}$, and $90^{\circ}$ based on the work platform, and then subjected to a flexural test in three test temperature environments of $-25^{\circ}C$, $25^{\circ}C$, and $60^{\circ}C$. As a result, PA12 had the maximum flexural strength in the direction of $90^{\circ}$ at $-25^{\circ}C$ and $0^{\circ}$ at $25^{\circ}C$ and $60^{\circ}C$. The glass bead-reinforced PA12 exhibited maximum flexural strength values at all test temperatures in the $0^{\circ}$ fabrication direction. The tendency of the flexural strength changes of the two materials was different due to the influence of the plane direction of the lamination layer depending on the type of stress generated in the bending test.

• Proceedings of the Korean Fiber Society Conference
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• 2002.04a
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• pp.313-316
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• 2002

고분자 물질과 유리섬유, 운모, 탄산 칼슘 그리고 점토 광물과 같은 다양한 무기물과의 복합체는 기계적 성질, 열적 성질과 같은 물리적 특성의 향상을 가져올 뿐만 아니라 이와 같은 특성들을 적은 비용으로 향상시킬 수 있는 장점을 가지고 있기 때문에 다양한 방면에서 널리 사용된다[1]. 이에 대해서, 최근 많은 발전을 이루고 있는 나노기술을 고분자와 무기 나노 입자의 복합체에 적용시키는 연구가 활발히 진행되고 있다. (중략)

• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.183-186
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• 2001

폴리에스테르/폴리아미드의 블렌드는 두 고분자의 단점을 상호 보완할 수 있을 뿐만 아니라 조성비에 의해 원하는 물성을 부여할 수 있는 장점이 있다. 이들 블렌드 중에서 폴리(에틸렌 테레프탈레이트)(PET)/폴리아미드(PA)의 블렌드의 경우 일반적인 폴리에스테르계의 블렌드에서 일어나는 에스테르 교환반응과 마찬가지로 에스테르-아미드 교환반응이 일어나며 이를 이용하여 두 고분자간의 상용성을 향상시키려는 연구가 보고된 바 있다. (중략)

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4457-4462
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• 2014

This paper presents an antenna design that can be applied to flexible transparent conducting film. The antennas shaping PIFA (Planar Inverted F-shpae Antenna) were produced on polyamide substrates, which are flexible. The IZTO/Ag/IZTO multilayer films were used for the antennas and exhibited superior electrical, optical and flexible characteristics. This study compared the transparency and performance of two antennas (IZTO/Ag/IZTO multilayer film, and Ag monolayer film). The operation frequencies were set to 5.18~5.32 GHz of WLAN (802.11a). The performance showed a maximum efficiency and peak gain of 89 % and 5.86 dBi, respectively.

• Membrane Journal
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• v.24 no.2
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• pp.88-99
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• 2014

Demand for water is increasing due to rapid population growth and increased industrial activities. Membrane technologies have attracted most attention as a promising advanced technology for the supply of sustainable water resources. Chemical and structural properties of polyamide membranes, one of the most widely used membranes in water treatment plant, has been reported to be affected by residual chlorine dissolved in water after chlorine disinfection. This paper focuses on the chlorine speciation at various solution pHs and change of surface properties/performance of polyamide membranes due to the chlorine exposure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.217-223
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• 2019

The application of 3D printing technology is expanding due to the production of the complex-shape parts and the one-step manufacturing process. Moreover, various technical solutions in 3D printing are emerging through continuous research and development. Representative technologies include SLS technology, in which a desired area is sintered and laminated by irradiating a powder-type material with a laser. In addition, high-performance engineering plastic parts are being manufactured in increasing numbers. In this study, tensile specimens were fabricated from polyamide 12, a widely available polymer, and the glass bead-reinforced polyamide 12. The specimen-build orientation was divided into 0°, 45°, and 90° on the fabrication platform, and the tensile test temperature was -25℃, 25℃, and 60℃. The test results showed that the tensile modulus of both materials decreases as the build orientation becomes closer to 90°. In addition, the tensile strength of glass bead-reinforced PA12 showed more dependence on the build orientation than PA12. In addition, the tensile modulus and tensile strength decreased with increasing test temperature.