• Design & Manufacturing
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• v.11 no.3
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• pp.25-28
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• 2017

The production of carbon fiber reinforced thermoplastics(CFRTP) parts using an injection/compression molding process that differs from the conventionally used fabrication methods was investigated Before the application of composite molding in the injection/compression molding process, a simple compression molding experiment was performed using a hydraulic press machine to determine the characteristics of resin impregnation and to obtain a basic physical property data for the CFRTP. Based on these results, injection/compression molded specimens were manufactured and an additional insert/over molding process was applied to improve the impregnation rate of the molded specimens. The results demonstrated that the tensile strength of the molded parts using the faster injection/compression process was similar to that of a hydraulic press molded product.

• Composites Research
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• v.30 no.3
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• pp.175-180
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• 2017

Currently, since carbon fiber reinforced plastics (CFRPs) are lightweight and have excellent physical properties, their demand has increased dramatically. Many works have studied the CFRPs based on recycled thermoplastics. In this study, the applicability of recycled composite was evaluated using recycled polyethylene terephthalate (PET). PET was collected from waste materials used in beverage bottles and processed to produce PET films. Optimal thermoforming temperature and time were analyzed by comparing the mechanical properties with forming temperature and time difference for producing PET films. CF mat and PET film were used to determine the suitable parameters for the optimum thermoforming of CF/PET composites. The mechanical properties of each thermoforming condition were verified by bending test. The degree of impregnation of the PET film into the CF mat was evaluated by cross-sectional photographs, whereas the interfacial properties were evaluated by interlaminar shear strength (ILSS). Ultimately, it was confirmed that the thermoforming condition for forming the CF/recycled PET composites yielding the optimal mechanical and interfacial properties was at $270^{\circ}C$ for 5 minutes.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.6
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• pp.9-13
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• 2014

Glass fiber reinforced thermoplastics(GFRTP) is made by adding chemical additive to glass fabric which is strong at a high temperate, incorrodible, and good at intensity and specific gravity. Although we focused on the weight lightening, the intensity of GFRTP is also important. To remedy thermoplastic resin's inferior property of matter to thermo-hardening resin, we formed several specimen, differing the chemical additive as Homo PP, MAPP 3%, Rubber 5%, and mixed. We put pressure of 5 type on the specimens. The analyses result for the different pressure, the resin spreads evenly, then the coherence is increased. Eventually, the mechanical properties are changed. When high intensity is needed, it is good idea to use polypropylene(PP) which has good coherence with glass fabric as chemical additive. We can get better intensity when we form the resin at the optimum pressure depending on mixing of chemical additive and glass fabric than when we increase the pressure.

• Composites Research
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• v.29 no.4
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• pp.161-166
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• 2016

Carbon nanotube buckypaper (CNTs-BP)/thermoplastic polyurethane (PU) elastomer composites were successfully fabricated. The CNTs-BP/PU nanocomposites exhibited simultaneous improvements in both tensile modulus and strength by 1360 and 430%, respectively, as compared to pure PU. Possible reinforcing mechanisms were evidenced by SEM analyses and tensile tests. The CNTs-BP/PU nanocomposites can be potentially used as an inter-reinforcing agent in ultra-lightweight, high-strength aircraft, carbon-fiber-reinforced plastics, etc.

• Fashion & Textile Research Journal
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• v.15 no.2
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• pp.294-301
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• 2013

Sustainable fashion & textile is more than eco fashion & textile with the concepts for the next generation's happiness, prosumer value, and community responsibility. This study considers methods to enhance fashion and textile industry sustainability in accordance to clothing types (material, product life and washing properties) and to investigate company strategies. Company strategies are of redesign with stock, volunteering & measuring trash amount, participation by evaluation stores, clerk environment education, hiring QC specialist and reinforcing partnerships. For the case of daily innerwear, throwing away and recycling is more efficient for the environment than laundering in the consumer use stage; subsequently, we recommend the use of polypropylene fiber (a cheap and an eco-friendly material) for this item that can be recycled and reformed after use. For the case of single layer clothing (such as sportswear, blouse or pants) we recommend the use of thermoplastic materials with welding or fuse assembling technology instead of a sewing method of seams as well as the recycle design that is simply melted and reformed into new clothing without an after use dissembling process. Secondhand use or resale is suitable for denim/jean items if the clothing has a storytelling or private history tag. Lastly, module-type jacket or coat shows the variety of styles with one clothing worn w/o collar or sleeve details and changed into vest/coat; in addition, it is possible to add or partly tear off some jacket/coat fibers of the felt material to reform it into a new design.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1999-2004
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• 2011

This research aims to develop polymer composites which can be used for PEMFC bipolar plate by injection molding process. Considering the moldability and stiffness, we used LCP(Liquid crystal polymer) as base resin. In order to improve electrical conductivity and mechanical properties, we chose carbon black, and both synthetic graphite and expanded graphite. The composites with different recipe are prepared for injection molding of PEMFC bipolar plate and CAE(Computer Aided Engineering) analysis was performed to predict melt flow and fiber orientation We did successfully fabricate the ASTM specimens by injection molding, and measure the electrical conductivity of the samples by using four point probe device. We measured mechanical properties such as flexural strength, flexural modulus and Izod impact strength. Conclusively, the electrical conductivity increased with increasing additive concentration, but both flexural strength and Izod impact strength decreased due to the brittle nature of carbon-based additives.

• Composites Research
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• v.35 no.1
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• pp.38-41
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• 2022

In this study, the strain rate dependent tensile and compressive properties of PP-LGF and TPO was investigated under the high strain rate by using the Split Hopkinson Pressure Bar (SHPB). The SHPB is the most widely used apparatus to characterize dynamic mechanical behavior of materials at high strain rates between 100 s^-1 and 10,000 s^-1. The SHPB test is based on the wave propagation theory which was developed to give the stress, strain and strain rate in the specimen using the strains measured in the incident and transmission bars. In addition, to verify the strain data obtained from SHPB, the specimen was photographed with a high-speed camera and compared with the strain data obtained through the Digital Image Correlation (DIC).

• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.489-501
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• 1997

Electropolymerization of 2-vinylnaphthalene (2-VN) and methylmethacrylate (MMA) with high radiation resistance property was conducted on the surfaces of carbon fibers by using a nonaqueous solution of comonomers dissolved in N,N-dimethylformamide containing sodium nitrate as a supporting electrolyte. The fabrication of carbon fiber/2-VN/MMA prepreg was performed electrochemically in 1:1 comonomer solution. Electropolymerization was conduced by changing the current density, initial comonomer concentration, and reaction time. The weight gain on the surface of the carbon fibers was measured by thermogravimetric analyser (TGA). The highest weight gain of 50 wt% was obtained at 600mA/g~800mA/g current density range, but the weight gain was rapidly decreased above 800mA/g current density. The weight gain was increased with the concentration of comonomer, while the concentration of electrolyte had almost no effect on the weight gain. At 300mA/g current density, weight gain rate was increased abruptly to the initial 30 minutes of reaction time. After that the rate was decreased due to the generation of gas bubbles. In order to check the effect of coated polymers on the radiation resistance, morphology changes before and after $\gamma$-ray irradiation was investigated for the composites.

• Composites Research
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• v.31 no.4
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• pp.122-127
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• 2018

Sandwich composites of carbon fiber reinforced plastic(CFRP) and polymer foam will be used to automobile and aerospace industry according to increasing importance of light weight. In this study, mechanical and heat resistance properties of sandwich composites were compared with type of polymer foam (polyethylene terephthalate(PET), polyvinylchloride(PVC), epoxy and polyurethane). All types of polymer foams were degraded to 30, 60, 120, 180 minutes in $180^{\circ}C$. After heat degradation, the polymer foams were observed using optical microscope and compressive test was performed using universal testing machine(UTM). Epoxy foam had the highest compressive property to 2.6 MPa and after thermal degradation, the mechanical property and structure of foam were less changed than others. Epoxy foam had better mechanical properties than other polymer foams under high temperature. Because the epoxy foam was post cured under high temperature. As the results, Epoxy foam was optimal materials to apply to structures that thermal energy was loaded constantly.