• Journal of Aerospace System Engineering
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• v.17 no.2
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• pp.71-77
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• 2023

Liquid Composite Molding (LCM), an Out of Autoclave (OoA) composite manufacturing process, has big advantages when making large and complex structures of airplanes. Since the importance of LCM process is increasing, FAA has suggested recommended guidance and criteria for the development of material and process specifications for LCM materials and process. The importance of LCM process is also raised by domestic composite material suppliers and OEM. This study suggested structures of material specifications and process specification of LCM materials. Material qualification method for LCM process and material was also developed in this study.

• Journal of the korean Society of Automotive Engineers
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• v.18 no.5
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• pp.96-120
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• 1996

현재 자동차용 복합재료를 생산하는데 유리한 제조방법으로는 압축성형 (Compression Molding), 액상성형(Liquid Molding), 인발성형(Pultrusion), 필라멘트 와인딩성형(Filament Winding)등이 있다. 압축성형은 현재 자동차 외장부품 성형에 널리 알려져 있는 SMC(Sheet Molding Compound)성형, 최근에 많은 연구가 되고 있는 LMPC(Low Pressure Molding Compound)성형, GMT(Glass Mat Reinforced Thermoplastics)성형 등이 있다. 액상성형은 RTM(Resin Transfer Molding)과 VARI (Vacuum Assisted Injection Molding), SRIM(Structure Reaction Injection Molding) 등이 있으며, 자동차 산업뿐만 아니라 일반 산업에서도 최근 많은 각광을 받고 있다. 그러므로 본 소고에서는 자동차용 복합재료의 제조에 널리 사용되는 성형공정에 대하여 간단히 살펴보고, 자동차 부품에 있어서의 복합재료 응용 현장과 최근 환경문제가 대두되면서 관심의 초점이 되고 있는 자동차용 복합재료 재활용 기술에 대하여 고찰하고자 한다.

• Composites Research
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• v.33 no.5
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• pp.247-250
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• 2020

In this study, the possibility of manufacturing a magnesium (Mg) composites reinforced with continuous silicon carbide (SiC) fibers was examined using a liquid pressing process. We fabricated uniformly dispersed SiC fiberAZ91 composites using a liquid phase pressing process. Furthermore, the precipitates were controlled through heat treatment. As a continuous Mg₂Si phase was formed at the interface between the SiC fiber and the AZ91 matrix alloy, the interfacial bonding strength was improved. The tensile strength at room temperature of the prepared composite was 479 MPa, showing excellent mechanical properties.

• Composites Research
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• v.16 no.1
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• pp.58-67
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• 2003

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.280-283
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• 2002

In the manufacturing of large scale composite structures, the cost-effective processing and the enhancement of structural performance are critical. One of the most effective ways for this purpose is to use stitched multiaxial warp knitted (MWK) perform in the resin transfer molding process. This study reports the effect of stitching on the mechanical properties of MWK composites, and the feasibility processing of the thick U-beam structure utilizing the stitched preforms. Permeability of the preform, viscosity and cure property of the epoxy resin have been measured. The results of resin flow analysis has been used in determining the gate/vent locations of the RTM mold. Cross-sectional observation of the channel beam prototype demonstrated that the resin impregnation was almost complete, except for some surrounding area of stitched yarns.

• Composites Research
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• v.20 no.5
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• pp.49-55
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• 2007

Nanocomposite blade for dicing semiconductor wafer is investigated for micro/nano-device and micro/nano-fabrication. While metal blade has been used for dicing of silicon wafer, polymer composite blades are used for machining of quartz wafer in semiconductor and cellular phone industry in these days. Organic-inorganic material selection is important to provide the blade with machinability, electrical conductivity, strength, ductility and wear resistance. Maintaining constant thickness with micro-dimension during shaping is one of the important technologies fer machining micro/nano fabrication. In this study the fabrication of blade by wet processing of mixing conducting nano ceramic powder, abrasive powder phenol resin and polyimide has been investigated using an experimental approach in which the thickness differential as the primary design criterion. The effect of drying conduction and post pressure are investigated. As a result wet processing techniques reveal that reliable results are achievable with improved dimension tolerance.

• Composites Research
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• v.31 no.6
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• pp.304-310
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• 2018

Autoclave process has been remaining as one of the most robust and stable process in fabricating structural composite part of aerospace industry. It has lots of advantages, however exhibits some disadvantages or limitations in capital investment and operation. Recently, there have been various Out-of-Autoclave process being researched and developed to overcome those limitations. In this study, laminate specimens were fabricated using LCM (Liquid Composite Molding) process, regarded as one of potential OoA process. DB (Double bagging), CAPRI (Controlled Atmospheric Pressure Resin Infusion), VAP (Vacuum Assisted Process) and Autoclave process were used for laminate specimens. Void content, Thickness, Tg (Glass Transition Temperature), ILSS (Interlaminar Shear Strength) and Flexural strength properties were evaluated for comparison. It is verified that Autoclave based specimen has uniform thickness distribution, the lowest void content and outstanding mechanical properties. And, CAPRI based specimen exhibits relatively good physical and mechanical properties over DB and VAP based specimen and comparable mechanical properties with autoclave based specimen.

• Composites Research
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• v.32 no.1
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• pp.1-5
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• 2019

In this study, Al1050 composites reinforced with uniformly dispersed, high volume fraction $TiB_2$ particles were fabricated by liquid pressing process and analyzed to microstructure, mechanical properties. Hardness, ultimate tensile strength and compressive yield strength of the 56 vol.% $TiB_2$-Al1050 composite increased to 10, 4.5 and 9.8 times, respectively, compared with those of the Al1050 due to dispersion hardening effect of uniformly dispersed $TiB_2$ in the Al matrix.

• Composites Research
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• v.33 no.2
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• pp.39-43
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• 2020

Recently, fabrication process of thermoplastic polyamide-based composites with recyclability as well as impact, chemical, and abrasion resistance have been widely studied. In particular, thermoplastic reactive resin transfer molding (TRTM) in which monomer with low viscosity is injected and in-situ polymerized inside mold has received a great attention, because thermoplastic melts are hard to impregnate fiber preform due to their very high viscosity. However, it is difficult to optimize the processing conditions because of high reactivity and sensitivity to external environments of the used monomer, ε-caprolactam. In this study, viscosity as an important process parameter in TRTM was measured during in-situ anionic polymerization of ε-caprolactam and the solutions for problems caused by high polymerization rate and sensitivity to moisture and oxygen were suggested. Reliability of the improved measurement technique was verified by comparing the viscosity behavior at various environmental conditions including humidity and atmosphere, and it is expected to be helpful for optimization of TRTM process.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.50-53
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• 2003

Carbon nannofiber reinforced Cu matrix composite has potential applications for electrically conducting materials having high strength and electrical conductivity. In this study, we have developed fabrication technology of the nanocomposites using a liquid pressing process. The process is to use the low pressure for infiltration of Cu melt into carbon nanofiber mat as the Cu melt is pressurized directly. The minimum pressure required for infiltration was calculated from force balance equation, permeability measurement and compaction behavior of carbon nanofiber. Also, the melting temperature and the holding time have been optimized.