• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.341-342
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• 2012

• Composites Research
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• v.33 no.2
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• pp.76-80
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• 2020

In this study, vacuum bag hot-press (V-HP) process can be used as an out-of-autoclave (OOA) process by improving the inefficient process of the autoclave forming method with excellent physical properties and surface quality. A carbon fiber composite was molded via V-HP process and analyzed the physical properties and microstructures between composites manufactured by autoclave (AC) process and hot-press process (HP). The tensile strength of the composite materials using the V-HP process was 320.6 MPa and the AC process samples found to be substantially close to the tensile strength of 335.3 MPa. As a result of confirming the surface quality of the composite material using SEM, it was confirmed that in the V-HP process, the removal state of pores due to volatile solvent in the resin was slightly lower than that of the AC process, but it had a considerably superior surface compared to the HP process.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.203-206
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• 2008

In this study, we focused on development of the adhesive insulator using the case for solid rocket motors. Material of insulator used unvulcanized rubber based on EPDM/kevlar. In case of front insulator, preforms was made by using hot press molding, and then modified nylon film was inserted between two preforms for boots manufacturing. Rear insulator included cylinder part was embodied by only one mold with special designed and manufactured shape in the process. Boots part of rear insulator was obtained by cutting machine with hard-metal cemented carbide.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1045-1047
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• 2017

In this study, we focused on development of the all-in-one case insulation for end-burning solid rocket motors. Material of insulation used unvulcanized rubber based on EPDM/kevlar. In case of boots insulation, preforms was made by using hot press molding, and then the tape was inserted between two preforms for all-in-one curing in the case. Finally bladder method was applied for curing of insulation.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.4
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• pp.85-94
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• 2004

Waste wood-plastic composite panels are made on different hot press molding conditions, and tested for apparent density, water absorption, expansion in thickness and flexural strength. From the test results, regardless of molding temperature and molding time, the apparent density of the composite panels is increased with an increase in the molding pressure, while their water absorption is decreased with an increase in the molding pressure. The flexural strength of the composite panels is markedly increased with increasing molding pressure, molding temperature and molding time, and tends to become nearly constant at a molding temperature of $120^{\circ}C$ and a molding time of 15min.

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.104.1-104
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• 2002

• Advanced Composite Materials
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• v.16 no.4
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• pp.361-376
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• 2007

Disposing of conventional fiber-reinforced polymers (FRPs) poses an environmentally challenging problem. Disposal of FRPs by combustion discharges carbon dioxide in the air because the resin of FRPs is made of fossil fuel. When they are disposed of in the ground, FRPs remain semipermanently without decomposing. In response to these problems, green composites are now being developed and are extensively studied as a material that produces a lower environmental burden. In this paper, green composites using kenaf fiber yarn bundles and PLA (poly(lactic acid)) are fabricated and their tensile properties are evaluated in the experiment. The tensile Young's modulus of all of the laminations is larger than that of PLA alone and the tensile strength of some laminations is larger than that of PLA alone. In particular, the value of UD composite of $0^{\circ$ shows double the tensile strength of PLA alone. Furthermore, the molding conditions for fabricating with a hot press are investigated and the heat resistant tensile properties of green composites are also reported.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.12
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• pp.1267-1271
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• 2012

Demand for optical glass device used for lighting could increase rapidly because of LED lighting market growth. The optical glass devices that have been formed by hot press molding process the desired optical performance without being subjected to mechanical processing such as curve generation or grinding. EL-Max material has been used for many engineering applications because of their high wear resistance, high compressive strength, corrosion resistant and very good dimensional stability. EL-Max is very useful for a glass lens mold especially at high temperature and pressure. The performance and reliability of optical components are strongly influenced by the surface damage of EL-Max during grinding process. Therefore, the severe process condition optimization shall be necessary for the highly qualified EL-Max glass lens mold. To get the required qualified surface of EL-Max, the selection of type of the diamond wheel is also important. In this paper, we report best grinding conditions of ultra-precision grinding machining. The grinding machining results of the form accuracy and surface roughness have been analyzed by using Form Talysurf and NanoScan.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.996-999
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• 2008

Aspheric polymer lens fabrication using isothermal compression molding is presented in this paper. Due to increasing definition of an image sensor, higher precision is required by a lens which can be used as a part of an imageforming optical module. Injection molding is a factory standard method for a polymer optical lens. But achievable precision using injection molding has a formidable limitation due to the machining of complex mold structure and melting and cooling down a polymer melt under high pressure condition during forming process. To overcome the precision requirement and limitation using injection molding method, isothermal compression molding is applied to fabrication of a polymer optical lens. The fabrication condition is determined by numerical simulations of temperature distribution and given material properties. Under the found condition, the lens having a high precision can successfully be reproduced and does not show birefringence which results often in optical degradation.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.4
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• pp.95-104
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• 2004

A styrene solution of waste expanded polystyrene with a crosslinking agent and an initiator was used as a binder for waste wood-plastic composite panels. The waste wood-plastic composite panels are prepared with various binder contents and filler-binder ratios by using a hot press molding method. The apparent density of the composite panels is increased with increasing binder content and filler-binder ratio, while their water absorption and expansion in thickness are decreased with increasing binder content and filler-binder ratio. The maximum flexural strength and wet flexural strength of the composite panels are obtained at a binder content of 35% and a filler-binder ratio of 0.8. Decreases in the flexural strengths of the composite panels due to water immersion at 20 and $100^{\circ}C$ are hardly recognized at binder contents of 30% or more.