• Design & Manufacturing
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• v.11 no.2
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• pp.15-19
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• 2017

Carbon fiber reinforced plastic (CFRP) is applied as structural material. CFRP is excellent in plane strength / stiffness and don't haves rust. Lightweight, rigid and robust at the same time as transportation material. Aluminum alloy and reinforcement material The application is increasing rapidly. In this study, the prototype of a semi - Monocoque structure frame, Longeron, Stringer, Skin of the aircraft, restraining the rigidity Clips of the aircraft was designated as the target product and the experiment was conducted. ln the experiment, (1) For CFRTP 3 points, data on heating, transfer, and cooling were measured using Thermo Couple, and optimum temperature required for flexible state was obtained. Heating was performed at a temperature 15% higher than the provided temperature. (2) By using a pneumatic press during molding, by dividing LH, center and RH according to the cooling time, thickness parameter of the target product due to the load is measured, and thickness control and time-deviations were analyzed and cross sections were observed with a low magnification microscope.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.454-454
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• 2007

Eye Glass Display (EGD) with microdisplay to realize the virtual display can make the large screen, so virtual image has been developed by using microdisplay panel. This paper shows study of spherical prism lens design and manufacture of a small size and light weigh EGD with 0.59" OLED panel. Code V is used and it designed an aspherical prism lens about eye relief 25mm and 42 degree of filed of view (FOV). With the application this aspheric prism lens to OLED type's microdisplay, virtual image showed 60 inch at 2m. It had less than 2% of distortion value and modulation transfer function in axial had 30% of resolution with 32 lp/mm spatial frequency. We made an injection molding bases to lens designed.

• Composites Research
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• v.31 no.6
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• pp.311-316
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• 2018

In the present study, the effect of GO in damping capacity of CF/epoxy laminates was studied via free vibration analysis. The composite laminates were manufactured by using vacuum assisted resin transfer molding technique. The damping properties of the prepared hybrid composites were determined in terms of natural frequency and damping ratio in free vibration test. The foremost aspire of this investigation was to compare the vibration properties i.e. natural frequency and modal damping of the prepared composites with the numerical results. The numerical study was carried out via FEA using $ANSYS^{TM}$ workbench software. The parametric study of the numerical models was also studied considering the beam free length and the beam thickness. It was found that the incorporation of GO enhanced the damping capacity of the composite and the variation of natural frequencies in mode1varied by 2-5% compared to the experimental study.

• Korean Journal of Metals and Materials
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• v.50 no.10
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• pp.729-734
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• 2012

This study investigated the effect of water absorption on the tensile properties of carbon-glass/epoxy hybrid composites at room temperature and $-30^{\circ}C$. To investigate the effect of the position of glass fabric in the hybrid composite on the tensile properties, the stacking pattern of the fiber fabrics for reinforcing was created in three different ways: (a) glass fabrics sandwiched between carbon fabrics, (b) carbon fabrics sandwiched between glass fabrics and (c) alternative layers of carbon and glass fabrics. They were manufactured by a vacuum-assisted resin transfer molding (VARTM) process. The results showed that there was surprisingly little difference in tensile strength at the two different temperatures with dry and wet conditions. However, the water absorption into the hybrid system affected the tensile properties of the hybrid composites at RT and $-30^{\circ}C$. When the glass fabrics were at the outermost layers, the hybrid composite had the lowest tensile properties. This is attributed to the fact that the composite had a relatively high water absorption rate.

• Design & Manufacturing
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• v.16 no.1
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• pp.1-8
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• 2022

The importance of fast and accurate body temperature measurement with a portable thermometer is increasing. In order to reduce the temperature measurement response time of the infrared ear thermometer, it is very important to develop a structure for a thermometer having an efficient heat transfer path. Most of the existing ear thermometers are single structures that do not consider thermal efficiency, which may delay measurement time and reduce measurement accuracy. Therefore, in this study, the upper part of the thermometer in contact with the ear is made of a thermally conductive material, and the lower part of the thermometer is made of a thermal barrier material so that heat can be concentrated on the infrared sensor of the thermometer by blocking the upper part of the heat. For the efficiency of production, it was intended to be manufactured through the double injection process, and for this purpose, in this paper, the optimal process parameters were derived through the double injection process analysis.

• Journal of the Korean Institute of Gas
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• v.18 no.1
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• pp.46-51
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• 2014

The purpose of this paper is to study of the vehicle lamp manufacturing system composing ultrasonic waves connection process. Making lamp assembly plant, it was produced in the separate process as the injection molding, ultrasonic waves bonding, annealing in the constant temperature, lamp assembling and packing. But the improvement method producing the lamp was added with one-step process by one automation technique. As a result, welding with ultrasonic waves process, the method decreased the energy consumption and noise during ultrasonic waves welding. Therefore, this method used the mathematics modeling for checking validity, it selected the stability and suitable controller using transfer function of plant and bode chart. In this study, the $180^{\circ}$ revolution control system to turn injection part upside down was $M_{eq}\;lcos{\theta}(t)$ because of gravity influence. It effected to unstable condition a system. For solving this problem, it aimed the linearization and stabilization of system by elimination $M_{eq}\;lcos{\theta}(t)$ as applying Free-forward control technique.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.146-149
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• 2005

The using of composite material is an aviation field but it changes into a general industry. Especially composites are expanding the use on transportation vehicles like automobiles, ships, and aircrafts. The main factor of this expansion is high specific strength. It can supply a high quality and efficiency of energy. But manufacturing of composite products requires many raw materials and tooling cost for special process, so we needs a reduction of these costs to achieve best efficiency. In the present study, we contrast the change of mechanical and physical properties between VaRTM(Vacuum Assisted Resin Transfer Molding) and hand lay-up process. VaRTM process can offer a high quality the same as autoclave products, and low cost like hand lay-up process. In the results of mechanical tests, VaRTM specimen is stronger than hand lay-up specimen and hand lay-up specimen became delamination. In the results of physical tests, the resin content of VaRTM specimen is lower than hand lay-up specimen. On micrograph, the strength of specimen by VaRTM between fiber and resin is stronger than that of one by hand lay-up. And the specimen by hand lay-up contains more defects than one by VaRTM. So, VaRTM process can practically apply for automobile engine hood. This paper shows that VaRTM process is one of the most suitable processes for composite parts of automobile.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.418-423
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• 2018

Recently, research and development of high-value leisure vessels has been carried out in Korea to revitalize the marine leisure industry and tap into the global maritime leisure market. FRP composite materials, which have excellent physical properties and are available for the manufacture of light hulls, are used widely. One of the most important design technologies is to secure structural safety of leisure vessels made from FRP composite materials. In this study, the structural strength was assessed for the design of an 8-meter high-speed planing leisure boat made from FRP composite materials. The design loads to verify the structural safety were calculated according to the rules for the classification of high speed light craft (KR, 2015), and structural analysis was conducted using a finite element model composed of an isotropic shell element, which has equivalent bending rigidity with the FRP sandwich panel. The analysis results were compared with the results of the strength test for fabricated specimens, and all internal structural components are sufficiently satisfied with the structural strength.

• Composites Research
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• v.15 no.6
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• pp.1-7
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• 2002

In VARTM process where a sacrificial medium is used to facilitate the resin flow, the velocity of resin varies drastically between the sacrificial medium and the fiber preform. Although the thickness-to-length ratio of a VARTM product is usually small, a 3-D analysis is prerequisite to analyze the lead-lag flow in the two different media. The problem associated with the full 3-D analysis is the CPU time. A full 3-D numerical mesh comprising large number of nodes requires an impractical CPU time on average computer platforms. In this study, a dual-scale analysis technique was developed. The flow analysis for the entire calculation domain was conducted in 2.5-D, and the 3-D analysis was performed for a small area of special concern. In some numerical examples, the local 3-D analysis could discover an eccentric flow pattern as well as the lead-lag flow that will inevitably be neglected in 2.5-D simulations. The global-local analysis technique practiced in this study can be used to analyze the intricate flow of resin through non-uniform media in affordable CPU times.

• Composites Research
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• v.30 no.3
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• pp.202-208
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• 2017

Resin transfer molding (RTM) is a mass production process that allows the fabrication of composites ranging in size from small to large. Recently, fast curing resins with a curing time of less than about 10 minutes have been used in the automotive and aerospace industries. The viscosity of resin is bound up with the degree of cure, and it can be changed rapidly in the fast-cure resin system during the mold filling process. Therefore, it is advantageous to experimentally measure and evaluate the degree of cure because it requires much effort to predict the flow characteristics and cure of the fast curing resin. DMA and dielectric technique are the typical methods to measure the degree of cure of composite materials. In this paper, the resin flow and degree of cure were measured through the multi-channel dielectric system. A total of 8 channels of dielectric sensors were used and resin flow and degree of cure were measured and compared with each other under various pressure conditions.