• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.359-365
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• 2000

Port facilities and marine structures used in marine environment were encountered to corrosion damages because of the influence of $Cl^-$. Generally, to protect these accidents, mainly applied anti-corrosion paint and epoxy coating. But it was still remained erosion-corrosion damage such as impingement erosion, cavitation erosion, deposit attack. There was needs to develope the new coating materials to protective those corrosion damages. This paper, polyester glass flake, vinylester glass flake lining and epoxy coating for SS were investigated electrochemical tests and cavitation erosion test for corrosion behaviour under sea water. The main results obtained are as follows, 1) Surface of epoxy coating appear erosion pin hole but surface of polyester glass flake and vinylester glass flake lining do not appear erosion pin hole after impingement-cavitation erosion test in sea water. 2) Weight loss of polyester glass flake and vinylester glass flake lining do not occur after impingement-cavitation erosion test in sea water. 3) Corrosion current density of polyester glass flake lining less drained than epoxy coating and substrate under corrosion potential.. 4) Corrosion current density of vinylester glass flake lining with three coating less drained than that of polyester glass flake lining with two coating.

• Polymer(Korea)
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• v.38 no.6
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• pp.726-734
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• 2014

Three different types of additives, thiokol, epoxidized natural rubber (ENR) and epoxidized linseed oil (ELO), were dispersed in an epoxy matrix before being used in glass fiber (GF) composites, and their effects on the mechanical and dielectric properties of epoxy resin and glass fiber reinforced epoxy composites (GF/EP) were examined. The addition of each of 7 phr ENR, 9 phr ELO and 5 phr thiokol into the epoxy resin increased the fracture toughness significantly by 56.9, 43.1, and 80.0%, respectively, compared to the unmodified resin. The mode I interlaminar fracture toughness of the GF/EP at propagation was also improved by 26.9, 18.3 and 32.7% when each of 7 phr ENR, 9 phr ELO, and 5 phr thiokol, respectively, was dispersed in the epoxy matrix. Scanning electron microscopy showed that the additives reduced crack growth in the GF/EP, whereas their dielectric measurements showed that all these additives had no additional effect on the real permittivity and loss factor of the GF/EP.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.1
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• pp.109-113
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• 2012

The LED failure rate greatly depends on the physical properties of packaging materials (epoxy). The glass transitions temperature (Tg) of the epoxy is one of the most important physical properties. Therefore, in the present study, various epoxies with high Tg were prepared and their failure shapes were analyzed. In addition, the failure shapes depending on the amount of epoxy and the wire bonding structure were measured. As a consequence, the lower failure rate was obtained with the smaller amount of epoxy. The safety of LED was improved with increasing the Tg of the epoxy.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.2
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• pp.203-209
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• 2010

In this study, the fatigue characteristics and life of a woven glass fabric/epoxy laminate composite applied to railway vehicles was evaluated. The fatigue test was conducted using a tension-tension load with a stress ratio R of 0.1 and frequency of 5 Hz. Two types of woven glass fabric/epoxy laminate composite was used in the fatigue test: with and without carbon/epoxy ply reinforcement. In addition, the fatigue life of the woven glass fabric/epoxy laminate composite was compared with that of aluminum 6005, which is used in the car body and underframe structures of railway vehicles. The test results showed that the failure strength and life of the woven glass fabric/epoxy laminate composite reinforced with three carbon/epoxy plies had a remarkable improvement compared with that of the bare specimen without reinforcement.

• Journal of Fisheries and Marine Sciences Education
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• v.9 no.2
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• pp.188-197
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• 1997

The fracture toughness of three different kinds of epoxy-matrix composites containing the same volume fraction of reinforcement and the variation of fracture toughness of glass-carbon fiber/epoxy hybrid composites due to the change of test temperature and different glass fiber content were investigated in this study. Glass fiber/epoxy composite provided much higher fracture toughness than that of other composites because of the high strain at failure of glass fiber. Particularly the carbon fiber/epoxy composite exhibited the low fracture toughness caused by the low strain energy absorbing capacity of carbon fiber. And it was found that the strain at failure of reinforcement and interfacial delamination absorbing a significant amount of impact energy played an important role to increase fracture toughness of composites. The fracture toughness of the glass-carbon fiber hybrid composites increased with increasing the glass fiber content and decreased with raising the test temperature. The residual stress arising from the different thermal expansion between the matrix and reinforcement influenced the fracture toughness of composites.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.4
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• pp.362-369
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• 2007

This paper was studied on the characteristics of acid resistance and thermal shock for epoxy coatings in the strong acidic environment. The exhaust gas system, such as a air preheater, desulfurization equipment, for industrial boiler is damaged by dew point corrosion. To protect the acid corrosion, the coating using nonmetal was applied. The electrochemical polarization test, acid resistance and thermal shock test for epoxy coatings were carried out. And the acid resistance and thermal shock characteristics, aspect, and electrochemical anti-corrosion characteristics for epoxy coatings in the strong acidic environment were considered. The main results are as followings: As the epoxy glass flake coating by acidic thermal shock was damaged to the crack, blistering and elution etc., the current density of epoxy glass flake coating is high. But the damage of epoxy metal complex coating by acidic thermal shock was not occurred. Therefore the characteristics of acid resistance and thermal shock for epoxy metal complex coating is better than those for epoxy glass flake coating.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.5
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• pp.649-656
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• 2013

A conventional epoxy-microsilica composite (EMC) and an epoxy-microsilica-nanosilicate composite (EMNC) were prepared in order to apply them to mold-type transformers, current transformers (CT) and potential transformers (PT). Nanosilicate was exfoliated in a epoxy resin using our electric field dispersion process and AC insulation breakdown strength at $30{\sim}150^{\circ}C$, glass transition temperature and viscoelasticity were studied. AC insulation breakdown strength of EMNC was higher than that of EMC and that value of EMNC was far higher at high temperature. Glass transition temperature and viscoelasticity property of EMNC was higher than those of EMC at high temperature. These results was due to the even dispersion of nanosilicates among the nanosilicas, which could be observed using transmission electron microscopy (TEM). That is, the nanosilicates interrupt the electron transfer and restrict the mobility of the epoxy chains.

• Steel and Composite Structures
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• v.15 no.3
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• pp.267-279
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• 2013

This article describes a simple and cost effective fabrication procedure by using hand lay-up technique that is employed for the manufacturing of thin-walled axi-symmetric composite shell structures with carbon, glass and hybrid woven fabric composite materials. The hand lay-up technique is very commonly used in aerospace and marine industries for making the complicated shell structures. A generic fabrication procedure is presented in this paper aimed at manufacture of plain Carbon Fabric Reinforced Plastic (CFRP) and Glass Fabric Reinforced Plastic (GFRP) shells using hand lay-up process. This paper delivers a technical breakthrough in fabrication of composite shell structures without any joints and wrinkling. The manufacture of stiffened CFRP shells, laminated CFRP shells and hybrid (carbon/glass/epoxy) composite shells which are valued by the aerospace industry for their high strength-to-weight ratio under axial loading have also been addressed in this paper. A fabrication process document which describes the major processing steps of the composite shell manufacturing process has been presented in this paper. A study of microstructure of the glass fabric/epoxy composite, carbon fabric/epoxy composite and hybrid carbon/glass/fabric epoxy composites using Scanning Electron Microscope (SEM) has been also carried out in this paper.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.9
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• pp.1681-1690
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• 1992

The effects of the stress ratio and the fiber orientation(0.deg./90.deg. and .+-.45.deg.) to the load direction on the fracture behavior of the glass/epoxy plain woven composites were studied. The tests were carried out using compact tension specimens under both static and fatigue loading. The values of $k_{a}$ obtained from the energy release rate are independent of notch depth(a/w=0.2~0.6) for the 0.deg./90.deg. specimens, but decreases with an increase in a/w for the .+-.45.deg. specimens. And $k_{q}$ has higher values than $k_{ASTM}$ has been evaluated by the ASTM E399 test procedure. It is shown in the relation between fatigue crack growth rate da/dN and stress intensity factor range .DELTA.K using modified shape correction factor that da/dN decreases with a decrease in stress ratio and is lower for .+-..deg. specimens than for 0.deg./90.deg. These phenomena can be explained by the crack deflection to the load direction.n.n.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.10
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• pp.1526-1533
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• 2004

The needs of walking assistant device such as the Ankle Foot Orthosis (A.F.O) are getting greater than before. However, most of the A.F.O are generally imported rather than domestic manufacturing. The major reason of high import reliability is the rack of impact properties of domestic commercial products. Therefore, this research is going to focus on the evaluation of impact properties of the A.F.O which has the high import reliability. Unfortunately, these kinds of researches are not performed sufficiently. This research is going to evaluate impact energy behavior in composite materials such as the glass/epoxy (S-glass, [0/90]sub 2S/) and the aramid/epoxy (Kevlar-29, woven type, 8 ply) of ankle foot orthosis. The approach methods were as follows. 1) The history of impact load and impact energy due to the various velocities. 2) Relationship between the deflection and damage shape according to the impact velocities. 3) The behavior of absorbed energy and residual strength rate due to the various impact velocities.