• Transactions on Electrical and Electronic Materials
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• v.14 no.1
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• pp.43-46
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• 2013

In order to develop electrical insulation material, organically modified layered silicate was incorporated into an epoxy matrix to prepare nanocomposite. Transmission electron microscopy (TEM) observation showed that organophillic clay was in an exfoliated state, while hydrophilic clay was not dispersed into nanolayers within the epoxy matrix. Epoxy/organophilic clay (2.8 wt%) nanocomposite was mixed and cured at $150^{\circ}C$ for 4.5 hr. I-V characteristics, volume resistance and dielectric properties for the cured nanocomposite were estimated. Current density increased with increasing temperature, and volume resistance decreased with increasing temperature, in neat epoxy and epoxy/organophilic clay (2.8 wt%) nanocomposite. As frequency increased, the dielectric loss value decreased in the two systems.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.10
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• pp.1322-1329
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• 2018

In this paper, the reliability test of three kinds of epoxy resin for GIS Spacer, which is a high voltage based heavy electric machine, AC electrical treeing experiments were performed. Three types of epoxy resins, Araldite B41, CT 5531 CI and B46, have slight viscosity differences. An non-uniform electric field, E = 1149.4 kV/mm, as the needle to plate electrode, a power source with a frequency of 1 kHz was applied to the tree electrode for accelerated deterioration. The treeing phenomena of the three kinds of epoxy resin all initiated, propagated, and destroyed by the branch tree. Epoxy Resin B46 was 145 times longer than B41 and 53 times longer than CT 5531CI. I think that the choice of epoxy resin is very important in choosing high voltage heavy electric machine insulation materials.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.107-108
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• 2011

The purpose of present study is to examine the application of effective curing to hardener-free epoxy-modified mortars. The epoxy-modified mortars are prepared with polymer-cement ratios, subjected to two types of curing conditions, and tested for compressive, flexural and tensile strengths. As a result, hardener-free epoxy-modified mortars with steam curing is markedly improved with increasing air-dry curing period. High strength development of the epoxy-modified mortars may be achieved by the dense microstructure by cement and the hardener of the epoxy resin in the mortars.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.237-240
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• 2002

Amino terminated polyetherimide(ATPEI) has been synthesized by bisphthalic anhydride arid m-phenylenediamine, after that characterized by differential scanning calorimetry(DSC), thermogravimetric analyzer(TGA). Fourier transform (FT-IR) spectroscopy and gel permeation chromatography(GPC). ATPEI was blend to improve the toughness of bisphenol-A type epoxy resin which was cured by nadic methyl anhydride(NMA). The fracture toughness and the molphology of the toughened epoxy resin was evaluated. The toughness of ATPEI modified epoxy resin was higher than that of the PEI modified epoxy resin. In addtion, carbon fiber/ATPEI modified epoxy resin composites were fabricated and the mechanical properties of the resulted composites were investigated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.10
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• pp.613-619
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• 2016

The aim of this study is to improve of dielectric properties using epoxy/nano alumina composites with adding glycerol diglycidyl ether (GDE:1,2 g). This paper deals with the effects of dielectric properties(${\epsilon}^{\prime}_r$ and $tan{\delta}$) for epoxy/nano alumina contents (1,3 phr) and GDE addition (1,2 g)composites. 5 kinds specimen were prepared with containing epoxy resins, epoxy nano alumina composites. Average particle size of nano used were 30 nm. The nano alumina used were gamma phase particles of spherical shape. The suppression of epoxy chain motion by addition of nano alumina+GDE decreased dielectric loss and relative permittivity magnitude.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.263-264
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• 2012

The purpose of present study is to examine the long-term strength improvement of hardener-free epoxy-modified mortars with steam curing. As a result, strength improvement of hardener-free epoxy-modified mortars is markedly improved with increasing of air-dry curing period. This is improved by markedly increase the degree of hardening of the hardener-free epoxy resin in the epoxy-modified mortars with additional air-dry curing period.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.771-773
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• 1988

The Mechanical strength and the electrical insulation properties of the Epoxy Resin vary with the formation of chemical reactions between Epoxy and curing agent. Therefore, to study their reactions is important for understanding the properties of the cured Epoxy. In this paper, to get the cured Epoxy having good electrical insulation property, it is studied the effects of the surrounding temperature during the cure process on the property of the cured Epoxy. In the experiment, Epoxy is cured with the surrounding temperature varied between -5[$^{\circ}C$] to 50[$^{\circ}C$]. As the results, it follows that the higher the temperature is, the faster the cross-link process is.

• Transactions on Electrical and Electronic Materials
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• v.11 no.2
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• pp.89-91
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• 2010

Partial discharge (PD) resistances were investigated for three types of samples: original epoxy resins, epoxy micro composites with and without the silane processing, and mixture composites with micro and nano particles. The PD was applied to these materials using rod, gap, and plane electrodes. The partial discharge resistance found in the micro composites was better than that found in the original epoxy resin. Moreover, the mixture composites of $SiO_2$ nano and micro particles had much larger resistances than the original epoxy resin or microcomposites. It can be regarded that this excellent property was due to the fact that the nano particles have a dense structure between the micro particles.

• Composites Research
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• v.28 no.6
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• pp.361-365
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• 2015

The influence of MWCNTs on fracture toughness properties of MWCNTs/Nickel-Pitch Fibers/epoxy composites (MWCNTs/Ni-PFs/epoxy) was investigated according to MWCNTs content. Nickel-Pitch-based carbon fibers (Ni-PFs) were prepared by electroless nickel-plating. The surface properties of Ni-PFs were determined by scanning electron microscopy (SEM) and X-ray photoelectron spectrometry (XPS). The fracture toughness of MWCNTs/Ni-PFs/epoxy was assessed by critical stress intensity factor ($K_{IC}$) and critical strain energy release rate ($G_{IC}$). From the results, it was found that the fracture toughness properties of MWCNTs/Ni-PFs/epoxy were enhanced with increasing MWCNTs content, whereas the value decreased above 5 wt.%. MWCNTs content. This was probably considered that the MWCNTs entangled with each other in epoxy due to an excess of MWCNTs.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.277-280
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• 2005

Epoxy-mortar composites have been wildly used as finishing and repairing materials in the construction because of their excellent properties. Conventional epoxy-mortars and concretes have an inferior applicability and cost performance ratio due to the two component mixing of the epoxy resin and hardener. In this study, we examined the engineering effect of compressive strength and flexible strength according to the various epoxy-hardener in underwater and humidity environment, and evaluated the hardener types and physical effect of Epoxy mortar using cement binder in underwater and air condition. In this study, it was clarified that the engineering properties of repairing epoxy-motars were effected by the type of hardener.