• 대한기계학회논문집A
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• 제20권1호
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• pp.79-87
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• 1996

SMC(Sheet Molding Compound) is made of unsaturated polyester resin and other additives reinforced with randomly distributed chopped fiberglass strands. Because of its higher stiffness per unit mass, SMC was used as a substitute for steel for automotive steel outer panels. Thus, understanding of flow characteristics during fabrication of SMC is of importance since the formation of weld line depends on material flow. In the present study, SMC compression molding simulations in the flat and T-shape molds were accomplished. During simulations, the preferential the preferential flow occurred at the low mold closing speed while plug flow was observed for the higher mold closing speed. When the preferential flow was observed, the weld line was seen at the final stage. For simulations, rigid-viscoplastic finite element method was applied. Self-contact algorithm was also applied in order to predict the formation of the weld line. Simulation results were compared to the experimental results available in the literature.

• 열처리공학회지
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• 제25권1호
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• pp.1-5
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• 2012

The purpose of this study is to prepare a high strength fiberglass reinforced metal. Aluminum covering was carried out over carbon materials such as carbon fiber in order to increase their wettability to molten metals such as aluminum. A sputtering apparatus with a cylindrical target was fabricated to carry out the covering. Sputtering was caused by glow discharge between the target and the two anode plates attached to its top and bottom. As the substrate for preliminary test, a thin carbon wire was used instead of carbon fiber, and the wire was placed at the central axis of the target. Aluminium coating was formed on the whole surface of the substrate. The formation rate and structure of coating were varied by controlling the electrical potential of substrate. When the substrate was electrically isolated, coating with columnar structure was formed with a formation rate of $15{\mu}m/hr$. In case of grounded substrate, coating with amorphous structure was formed with a formation rate of $7{\mu}m/hr$.

• Structural Engineering and Mechanics
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• 제39권4호
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• pp.499-520
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• 2011

The effectiveness of a technique for the repair of reinforced concrete members in combination with a technique for the repair of masonry walls of infilled frames, damaged due to cyclic loading, is experimentally investigated. Three single - story, one - bay, 1/3 - scale frame specimens are tested under cyclic horizontal loading, up to a drift level of 4%. One bare frame and two infilled frames with weak and strong infills, respectively, have been tasted. Specimens have spirals as shear reinforcement. The applied repair technique is mainly based on the use of thin epoxy resin infused under pressure into the crack system of the damaged RC joint bodies, the use of a polymer modified cement mortar with or without a fiberglass reinforcing mesh for the damaged infill masonry walls and the use of CFRP plates to the surfaces of the damaged structural RC members, as external reinforcement. Specimens after repair, were retested in the same way. Conclusions concerning the effectiveness of the applied repair technique, based on maximum cycles load, loading stiffness, and hysteretic energy absorption capabilities of the tested specimens, are drawn and commented upon.

• Corrosion Science and Technology
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• 제7권1호
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• pp.6-12
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• 2008

Non-metallic composite overwrap repair methods utilize resin based fiber-reinforced composite materials, which have higher specific strength to weight ratio and stiffness, superior corrosion and fatigue resistance, and substantially reduced weight when compared to carbon steel. Non-metallic repair methods/systems can allow desired functional properties to be achieved at a respectable economic advantage. For example, non-metallic composite repair systems have at least a 50 year design stress of 20 ksi and approximately 25% of the short term tensile strength of fiberglass. For these systems, the contribution of the repaired steel to the load carrying capability need not be considered, as the strength of the repair itself is sufficient to carry the internal pressure. Worldwide experience in the Oil & Gas industry confirms the integrity, durability, inherent permanency, and cost-effectiveness of non-metallic composite repair or rehabilitation systems. A case study of a recent application of a composite repair system in Saudi Aramco resulted in savings of 37% for offshore subsea line and 75% for onshore above grade pipeline job. Maintaining a pipeline can be costly but it is very small in comparison to the cost of a failure. Pipeline proponents must balance maintenance costs with pipeline integrity. The purpose is not just to save money but also to attain a level of safety that is acceptable. This technology involves the use of an epoxy polymer resin based, fiber-reinforced composite sleeve system for rehabilitation and /or repair pipelines.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 B
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• pp.717-720
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• 1998

On the study, The activated carbon assemblies(ACA) were prepared by activation of the coated glass mat(woven type) with phenolic resin at $700^{\circ}C$ under $N_2$ after drying and curing processes. Surface of the ACA was continuously modified with $N_2$, $CO_2$ or $NH_3$ at $700^{\circ}C$ for 2 hour for comparison of adsorptive characteristics between the ACA and commercial activated carbon cloth. The ACA showed high surface areas up to $2440\;m^2/g$ when converted into the coated carbon base, and the surface was investigated by FT-IR and XPS. The basic ACA modified with $NH_3$ displayed the efficient removal capability of $SO_2$, which is 75% of that in commercial activated carbon cloth. Therefore, it has proved the applicability of ACA as an inexpensive materials for Dry de-SOX system.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권2호
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• pp.185-198
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• 2017

The application of composites as an alternative material for marine steel hatch covers is the subject of this study. Two separate approaches are considered; weight reduction approach and strengthening approach. For both approaches Finite Element Analysis (FEA) was performed using ANSYS software. Critical design parameters of the composite hatch cover and FEA are discussed in details. Regarding the weight reduction approach; steel hatch covers of a bulk carrier were replaced by composite covers and a weight reduction of 44.32% was achieved leading to many benefits including fuel saving, Deadweight Increment and lower center of gravity of the vessel. For the strengthening approach; the foremost hatch cover was strengthened to withstand 150% of the load required by IACS for safer navigation while no change in weight was made between the steel and composite covers. Results show that both approaches are feasible and advantageous.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권1호
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• pp.23-26
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• 2003

This paper presents conceptual design and 3-D electromagnetic analysis of IMVA transformer with BSCCO-2223 High Tc Superconducting (HTS) tapes. The rated voltages of each sides of the transformer are 22.9 kV and 6.6 kV, and double pancake windings were adopted. High voltage and Low voltage sides were composed of several double pancake windings. Four HTS tapes were wound in parallel for the windings of low voltage side and were transposed in order to distribute the currents equally in each conductor The transformer core was designed as a shell type core made of laminated silicon steel plates and the core is separated with the windings by a cryostat with Fiberglass Reinforced Plastics(FRP). A sub-cooling system using L$N_2$ were designed to maintain the coolant temperature 65K. Finally perpendicular components of magnetic field applied to tapes were calculated 0.247 in the rated operation using 3-D analysis. A real 1MVA HTS transformer will be manufactured in near future based on the design parameters presented in this paper.

• 대한치과기공학회지
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• 제42권1호
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• pp.27-33
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• 2020

Purpose: This study is to compare and analyze the precision of glass fiber resin dentures. Methods: A lower edentulous model was prepared. Ten study models were produced using Type IV stone. Ten wax lower resin dentures containing artificial teeth were prepared. The lower wax denture was buried with plaster and deflasking was performed to remove the wax. Five conventional lower resin dentures and five glass fiber lower resin dentures were produced. The scanning spray was coated on the impression surface and then scanned. Independent sample t-test were performed using statistical software. Results: In the color different map, which is a qualitative evaluation, the green area of the precision of the conventional lower resin denture occupied the whole. The glass fiber conventional resin dentures had many negative and positive area. In quantitative evaluation, the RMS of conventional lower resin was 89.83 ㎛ and that of fiberglass resin was 224.92 ㎛. The two groups showed statistically significant differences (p<0.05). Conclusion: Conventional lower resin dentures were superior in precision, and glass fiber resin dentures would have to improve the process.

• 한국해양공학회지
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• 제18권4호
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• pp.52-58
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• 2004

A Semi-Autonomous Underwater Vehicle (SAUV), capable of simple work on the seabed, is under development in KRISO-KORDI. This SAUV pressure vessel is composed of fiberglass reinforced plastic (FRP), and is also manufactured to carry electronic equipment. The objective of this paper is to describe the safety check for the pressure vessel. This is achieved fly conducting structural analysis and testing in a pressure tank. Strain and stress test results, under unit load, are obtained fly using ANSYS in linear structural analysis. Local buckling analysis are performed with NASTRAN at the middle oj the cylindrical hull. The first test, using linear structural analysis, is unsuccessful, as buckling occurred. During the second test, linear structural analysis, combined with local buckling analysis, is conducted. There is no buckling up to 250 m when both ANSYS and NASTRAN are used.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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• pp.397-400
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• 1998

On the study, The activated carbon assemblies(ACA) were prepared by activation of the coated glass mat(woven type) with phenolic resin at $700^{\circ}C$ under $N_2$ after drying and curing processes. Surface of the ACA was continuously modified with $N_2$, $CO_2$ or $NH_3$ at $700^{\circ}C$ for 2 hour for comparison of adsorptive characteristics between the ACA and commercial activated carbon cloth. The ACA showed high surface areas up to $2440\;m^2$/g when converted into the coated carbon base, and the surface was investigated by FT-IR and XPS. The basic ACA modified with $NH_3$ displayed the efficient removal capability of $SO_2$, which is 75% of that in commercial activated carbon cloth. Therefore, it has proved the applicability of ACA as an inexpensive materials for Dry de-SOX system.