• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.3
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• pp.247-254
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• 2010

Due to lightweight and high durability of glass-fiber reinforced polyester (GFRP) materials, they are promising alternatives to conventional construction materials such as steel, concrete and wood. As good application examples of GFRP materials, several types of temporary arch bridges were suggested and verified by finite element analyses in our previous study where snap-fit GFRP decks were applied. In this paper, we conduct a structural performance test to verify safety and serviceability of the temporary arch bridge, where snap-fit GFRP decks are assembled by bolts. The structural problems occurred in this test are also discussed and improvement of temporary arch bridges is suggested to resolve the occurred structural problems.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.3
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• pp.217-223
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• 2008

Glass-fiber reinforced polyester (GFRP) composite material is a promising alternative to existing construction materials such as steel, concrete and wood due to light weight and high durability of GFRP composite material. If a temporary arch bridge is built by GFRP composite deck, rapid construction of the bridge and reuse of the GFRP composite deck are possible. In this paper, we develop a type of temporary arch bridges that can be built by easy assembling of GFRP composite decks. For this purpose, several possible types of temporary arch bridges are suggested and verified by finite element analysis.

• Geomechanics and Engineering
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• v.5 no.2
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• pp.87-97
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• 2013

In this paper, a novel fibrous material known as axially reinforced braided composite rods (BCRs) have been developed for reinforcement of soils. These innovative materials consist of an axial reinforcement system, comprised of longitudinally oriented core fibres, which is responsible for mechanical performance and, a braided cover, which gives a ribbed surface texture for better interfacial interactions with soils. BCRs were produced using both thermosetting (unsaturated polyester) and thermoplastic (polypropylene) matrices and synthetic (carbon, glass, HT polyethylene), as well as natural (sisal) core fibres. BCRs were characterized for tensile properties and the influence of core fibres was studied. Moreover, BCRs containing carbon fibre in the core composition were characterized for piezoresistivity and strain sensing properties under flexural deformation. According to the experimental results, the developed braided composites showed tailorable and wide range of mechanical properties, depending on the core fibres and exhibited very good strain sensing behavior.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.276-281
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• 2008

Glass-fiber reinforced polyester(GFRP) composite material is a promising alternative to existing construction materials such as steel, concrete and wood. One of passible applications of GFRP composite material is to build temporary bridges by assembling GFRP composite decks. In this paper, we develop a system of temporary arch bridges that can be built by easy assembling of GFRP composite decks. For this purpose, several types of temporary arch bridges are suggested and verified by FE analysis.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.1
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• pp.162-174
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• 1992

Blades are one of the critical parts of the wind machine. This paper presents a design procedure for the blade of a 7m diameter horizontal axis wind turbine with the constraint conditions of stresses and fundamental frequency. This blade consists of glass/polyester woven fabric and unidirectional prepreg. It was firstly designed by the classical beam theory on the assumption that torque box sustains all external loads and the reliability of the blade was then inspected in the preliminary estimation by using FEM.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.44 no.3
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• pp.250-256
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• 2008

Generally the side plate materials of FRP ship are composed of glass fiber and unsaturated polyester resin composites(GFRP composites). In this study, the effect of applied load and sliding speed on friction and wear characteristics of these materials were investigated at ambient temperature by pin-on-disc friction test. The cumulative wear volume, friction coefficient and wear rate of these materials for SiC abrasive paper were determined experimentally. The cumulative wear volume showed a tendency to increase nonlinearly with increase of sliding distance and was dependent on applied load and sliding speed for these composites. The friction coefficient of GFRP composites was increased as applied load increased at same sliding speed in wear test. It was verified by SEM photograph of worn surface that major failure mechanisms were microfracture, deformation of resin, cutting and cracking.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1145-1148
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• 2007

Resilient materials are generally used for the floating floors to reduce the floor impact sound. Dynamic stiffness of resilient material, which has the most to do with the floor impact sound reduction. The resilient materials available in Korea include EPS (Styrofoam), recycled urethane types, EVA (Ethylene Vinylacetate) foam rubber, foam PE (Polyethylene), glass fiber & rock wool, recycled tire, foam polypropylene, compressed polyester, and other synthetic materials. In this study, we tested floor impact sound reduction characteristic to a lot of kinds of resilient material. The result of test showed that the amount of the heavy-weight impact sound reduction appeared by being influenced from this dynamic stiffness of resilient material. The dynamic stiffness looked like between other resilient materials, a similar to the amount of the heavy-weight impact sound reduction was shown.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.830-834
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• 2008

Resilient materials are generally used for the floating floors to reduce the floor impact sound. Dynamic stiffness of resilient material, which has the most to do with the floor impact sound reduction. The resilient materials available in Korea include EPS (Styrofoam), recycled urethane types, EVA (Ethylene Vinylacetate) foam rubber, foam PE (Polyethylene), glass fiber & rock wool, recycled tire, foam polypropylene, compressed polyester, and other synthetic materials. In this study, we tested floor impact sound reduction characteristic to a lot of kinds of resilient material. The result of test showed that the amount of the Light-weight impact sound reduction appeared by being influenced from this dynamic stiffness of resilient material. As the decreasing dynamic stiffness of resilient material, the impact sound reduction amount is increased, especially in the low frequency domain.

• Elastomers and Composites
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• v.48 no.4
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• pp.276-281
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• 2013

Polyester type polyurethane foam modified with acrylic polyol was prepared by quasi prepolymer method. Thermal and dynamic mechanical properties of polyurethane foam were analysed by thermal gravimetric analysis(TGA) and dynamic mechanical analysis(DMA). Also, glass transition temperature was measured by differential scanning calorimeter(DSC). As acrylic polyol contents were increased, thermal stability measured by TGA was slightly decreased. Storage modulus was increased and tan delta was decreased with increasing of acrylic polyol contents.

• Journal of Korean Home Economics Education Association
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• v.7 no.1
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• pp.1-10
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• 1995

This study was intended to provide an improved method for testing textiles in high school. Four kinds of test subjects were selected and applied to the classes. Problems of the methods in the textbooks were corrected as follows: 1)Burning test: The number of specimen is reduced to 3 kinds of fibers(cotton, wool, and polyester) and recommends are given to make result by comparing with the burning characteris-tics of paper and hair. 2) Absorbency test: Test Method is changed to drop test. The result is recorded by measuring time required for the water drops absorbed to the specimen. 3) Wrinkle recovery test: A glass is provided instead of metal weight. The method of measuring angle which is made by the specimen is shown in figure. 4) Effects of Detergent: 0.2% of detergent solution is provided before class. The amount of oil and carbon black is specified. Students have generally agreed that the improved methods were better than those in the text-books after they made the above 4 recommendable experiments(p<.001)