• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.81.3-81.3
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• 2015

Carbon Fiber Re-enforced Polymer (CFRP) has replaced steel, especially for mobile devices. As CFRP is stiff and light-weight, it has been applied to airplane, sport car, golf clubs, semiconductor transporter, satellites, etc. In the telescope, the plastic material was introduced to the supporting tubes or rods connecting the primary mirror assembly and the secondary mirror structure. Nowadays, even the mirror itself is produced by CFRP. In this poster, material properties and production of CFRP telescopes are presented, and pros and cons are discussed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.2
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• pp.171-181
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• 2004

This paper developed the theoretical method to predict structural performances and weight reduction rates of a carbody when its materials should be substituted. For the material substitution design of the carbody, the bending, axial and twisting deformations are evaluated under the constant stiffness and strength conditions. For the design of the primary structures such as the center beams, the cross beams and the cantrails, the bending and axial deformations are investigated under the condition of the constant bending stiffness, the constant bending or buckling strength by considering both the material properties and the cross sectional shapes. The developed indices to measure the weight reduction by the material substitution give good informations on the weak and strong points of a carbody design.

• Elastomers and Composites
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• v.57 no.4
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• pp.197-204
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• 2022

Recently, the demand has increased for protective clothing materials capable of shielding the wearer from bullets, fragment bullets, knives, and swords. It is therefore necessary to develop light and soft protective clothing materials with excellent wearability and mobility. To this end, research is being conducted on hybrid design methods for various highly functional materials, such as carbon nanotube (CNT) sheets, which are well known for their low weight and excellent strength. In this study, a hybrid protective material using CNT sheets was developed and its performance was evaluated. The material design incorporated a bonding method that used a binder for interlayer combination between the CNT sheets. Four types of binders were selected according to their characteristics and impregnated within CNT sheets, followed by further combination with aramid fabric to produce the hybrid protective material. After applying the binder, the tensile strength increased significantly, especially with the phenoxy binder, which has rigid characteristics. However, as the molecular weight of the phenoxy binder increased, the adhesive force and strength decreased. On the other hand, when a 25% lightweight-design and high-molecular-weight phenoxy binder were applied, the backface signature (BFS) decreased by 6.2 mm. When the CNT sheet was placed in the middle of the aramid fabric, the BFS was the lowest. In a stab resistance test, the penetration depth was the largest when the CNT sheet was in the middle layer. As the binder was applied, the stab resistance improvement against the P1 blade was most effective.

• Resources Recycling
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• v.16 no.4
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• pp.61-67
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• 2007

In viewpoints of environmental and resource conservation, it is desirable to utilize fly ash generated from domestic coal power stations as light constructive material. Furthermore, the demand of light constructive materials has been increased as many building tend to become highly multistory buildings. In demonstration of converting fly ash to light constructive materials, the Dwight-Lloyd kiln of which the operation is relatively easy and the reliability very high has been informed to be only commercialized plant over the world. In this review, Dwight-Lloyd kiln plant operated at Oomura coal power station in Japan is explained. Circular grate kiln, Shaft kiln, Rotary kiln plants that are under developed is also introduced.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.406-411
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• 2003

This paper deals with the effect of laser material processing on the EMU production technique. Material processing with lasers takes advantage of all the characteristics of laser light. The high energy density and directionality achieved with lasers permits strong localized heat- or photo-treatment of materials with spatial resolution below one micrometer. The pulsed and mono-chromatic light allows the control of depth of heat treatment or selective excitation. The laser beam can be moved to process large areas, is a sterile tool and is no subject to wear and tear. Using laser processing have taken more interests in EMU production for improving the rigidity, weight reduction, crash durability, and cost savings so that their application to auto-bodies has been increased.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.3
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• pp.253-260
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• 2016

This paper proposes a planar Log-Periodic Dipole Array(LPDA) antenna with light-weight supporting structure for installing on an aircraft. The proposed antenna is designed by applying a planar skeleton supporting structure that has light-weight for an aircraft and is capable of withstanding structural vibration. The material of the planar skeleton supporting structure is a Polyether ether ketone(Peek) which has excellent characteristics on strength and temperature. The proposed antenna is fabricated by attaching the radiating elements of the LPDA on both sides of the supporting structure. The changed input impedance due to the dielectric material of the supporting structure was compensated for by controlling the distance and length of several radiating elements. The 10-dB return loss bandwidths of the designed planar LPDA antenna with light-weight supporting structure are obtained as 0.4~3.1 GHz(7.3:1) in the simulation and 0.41~3.5 GHz(8.2:1) in the measurement. The average gains in 0.5~3 GHz band are 6.77 dBi in the simulation and 6.55 dBi in the measurement. Therefore, we confirm that the designed antenna is appropriate to be installed on an aircraft due to its light-weight structure and wideband directional radiation characteristics.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.177-180
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• 2008

Recently, the research of FRP bar as an alternative reinforcing material in reinforced concrete structures has increased to get an innovative solution to the corrosion problem. In addition to the noncorrosive nature of FRP materials, they also have a high strength-to-weight ratio. Therefore, when light weight concrete reinforced with FRP bar is used in marine environment, for instance floating structures, some advantages can be expected. But researches for the light weight concrete structure using FRP bar as a flexural reinforcement are limited to date. In this paper, the concrete shear contribution of the light weight concrete beam reinforced with GFRP bar was studied. Experiment for beams varying concrete compressive strengths and flexural reinforcement ratios was conducted and analysed. The test results showed that 75% of values obtained from proposed equation in preceding research were well agreed with the test results and were better results than the one predicted by the ACI 440.1R-06 code.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.237-239
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• 2011

This study was performed to investigate the influence of curing temperature on the properties of light weight foamed concrete, manufactured on-site construction according to the various experimental factor such as temperature of material, curing temperature in air(5, 10, 20℃), curing time in air(5, 10, 15hour), and target density of hardened state(0.8, 1.2t/㎥). As a result, the influence of the curing temperature on various properties of foamed concrete is greater than curing time. When increasing temperature and time in air curing, progress of hydration is fast and compressive strength is increasing more and more. However, when considering the productivity, minimum curing time is required 15hours at 5℃, 10hours at 10℃, and 5hours at 20℃. If this condition is not required, there is some crack due to volume expansion on the surface of light weight foamed concrete.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.2
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• pp.235-240
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• 2010

The recent trend of vehicle design aims at crash safety and environmentally-friendly aspect. For the crash safety aspect, energy absorbing members should be absorbed with collision energy sufficiently. But vehicle structure must be light weight for the environmentally-friendly aspect, in order to improve fuel efficiency and to reduce tail gas emission. Therefore, the light weight of vehicle must be achieved in a status of securing safety of crash. An aluminum or CFRP (Carbon Fiber Reinforced Plastics) is representative one among the light-weight materials. In this study, impact collapse behavior of circular hybrid thin-walled member is evaluated. The hybrid members are manufactured by wrapping CFRP prepreg sheets outside the aluminum circular members in the autoclave. Because the CFRP is an anisotropic material whose mechanical properties change with its stacking condition, special attention is given to the effects of the stacking condition on the collapse behavior evaluation of the hybrid thin-walled member. Collapse mode and energy absorption capability of the hybrid thin-walled member are analyzed with change of the fiber orientation angle and interface number.

• Journal of the Korea institute for structural maintenance and inspection
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• v.2 no.4
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• pp.186-193
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• 1998

The purpose of this research is to seek properties of flowing light-weight aggregate concrete and possibility of application. The experimental analysis results by using light-weight aggregate and industrial waste such flyash, furnace slag are as follow. 1) The research shows that flowing light-weight aggregate concrete of slump 23~27cm, slump flow 58~69 cm is possible, but material segregation is appeared above slump 26.5cm and slump flow 65 cm. 2) If mixing ratio of flyash is increase, strength deterioration is about 25 % in early age. It showed that effectiveness of long time strength improvement because strength manifestation ratio is above 95% in a long term. 3) This research showed possibility of substitution of blast furnace slag because strength deterioration by using mixing of furnace slag was appeared small deterioration range as below 10 %. 4) Each experimental compressive strength ratios were 77 %(1st week), 86 %(2nd week), 109 %(8th week), 115 %(13th week), 125 % (26th week) on the basis of 28 days. If mixing ratio of flyash is increase, long term strength increase ratio is improved.