• Composites Research
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• v.26 no.5
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• pp.295-302
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• 2013

In this study, Al5052/CFRP composites were fabricated for an automobile component by compression molding process inside a U-channel mold. Al5052 sheet were treated by sand blasting with two different particle sizes. Accordingly, surface roughness (Ra) values of $4.25{\mu}m$ and $1.85{\mu}m$ were obtained for the treated Al5052 sheets. The effect of surface roughness of Al5052 sheets on the adhesion and mechanical properties of Al5052/CFRP composites have been evaluated. Shear lap test and 3-point bending test were conducted. Results showed that the shear load for the composite fabricated by using the treated Al5052 sheets with Ra value of $1.85{\mu}m$ and $4.25{\mu}m$ were 3 and 5 times higher than Ra value of $0.73{\mu}m$ of the composite fabricated by using the untreated sheet. The bending stress of 200MPa was obtained for the composite fabricated with untreated Al5052 sheets. The bending stress increased to 400MPa when the composite fabricated from treated sheets. However, the bending stress was not influenced by treating condition through sand blasting.

• Journal of Adhesion and Interface
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• v.16 no.1
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• pp.15-21
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• 2015

In this study, rheological properties and flow dynamics in roll coating process of basecoat paints have been investigated for automotive precoated metal (PCM) sheet applications. Various rheological properties for basecoats with three colors (black, blue, and silver), such as shear viscosity data at room temperature and elastic/viscous moduli under thermal curing condition, have been measured using a rotational rheometer. It is found that the relative portion of function groups inside basecoats and their viscosity level have greatly affected the formation of crosslinked networks by thermal curing. Also, operability coating windows for basecoats have been established in three-roll coating process system by observing their flow instabilities such as ribbing and cascade. It is confirmed that rheological approaches applied in this study have been usefully applied to develop environmentally-friendly PCM coating technology and optimally control the coating operations for non-Newtonian PCM paints.

• Composites Research
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• v.31 no.1
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• pp.17-22
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• 2018

Long Fiber Prepreg Sheet (LFPS) has the advantages of excellent production efficiency and formability for complex shapes compared to conventional continuous fiber reinforced composites. When fibrous composites are used with different materials, joining method is important because strength of the joining part determines the strength of the hybrid structure. In this study, the adhesive joint strengths of co-cured LFPS and aluminum were evaluated under various surface treatment conditions and environmental conditions (temperature and moisture conditions). Mechanical abrasion and plasma exposure were used for the surface treatment. The adhesive joints experienced various surface treatments were tested by using single lap joint specimens. Adhesive strengths under various conditions were compared and the most appropriate condition was determined.

• Polymer(Korea)
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• v.38 no.3
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• pp.307-313
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• 2014

The physical properties of functionalized graphene sheet (FGS)/poly(ethylene-co-vinyl acetate) (EVA) was examined with various kinds of EVA, having vinyl acetate (VA) contents in the range of 0 to 40 wt%. The compatibility between FGS and EVA was enhanced as the polar VA content of EVA increased. Thus, the dispersion of FGS in EVA became finer, and the decrease of surface resistivity and the increase of tensile modulus by the added FGS became more effective when the VA content of EVA was high. When the VA content was low, the elongation at break was reduced drastically by added FGS due to the poor adhesion of FGS/EVA interface. The crystallization of EVA was generally retarded by the interaction with dispersed FGS. However, when both the VA content of EVA and the added amount of FGS were low, the crystallization of EVA was enhanced, probably due to the predominant nucleating effect by FGS.

• Journal of Adhesion and Interface
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• v.12 no.3
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• pp.99-104
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• 2011

Currently, automotive pre-primed coatings has been developed to overcome environmental regulations and to reduce manufacturing cost in automotive industry. By these reasons, an automotive pre-primed system has been investigated to remove the wash and pre-treatment process using a roll coating application. It is required to develop non-weldable pre-primed system for automotive structural adhesives, because pre-primed sheet coated with organic compounds is hard to be assembled by welding process. Primer 1 (polyester type) and primer 2 (urethane type) were designed to satisfy flexibility and formability for non-weldable pre-primed system. According to the results of physical property test of the primers, adhesion test such as single-lap shear test and T-peel test, primer 1 (polyester type) had better physical properties such as pencil hardness, solvent resistance, flexibility and adhesion with automotive adhesive than that of primer 2 (polyurethane type). In addition, the possibility of the non-weldable pre-primed system was applicable to automotive assembly process in place of welding process.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.301.1-301.1
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• 2016

We report an ultraclean, cost-effective, and easily scalable method of transferring and patterning large-area graphene using pressure sensitive adhesive films (PSAFs) at room temperature. This simple transfer is enabled by the difference in wettability and adhesion energy of graphene with respect to PSAF and a target substrate. The PSAF transferred graphene is found to be free from residues, and shows excellent charge carrier mobility as high as ${\sim}17,700cm^2/V{\cdot}s$ with less doping compared to the graphene transferred by thermal release tape (TRT) or poly(methyl methacrylate) (PMMA) as well as good uniformity over large areas. In addition, the sheet resistance of graphene transferred by recycled PSAF does not change considerably up to 4 times, which would be advantageous for more cost-effective and environmentally friendly production of large-area graphene films for practical applications.

• Applied Chemistry for Engineering
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• v.2 no.3
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• pp.289-299
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• 1991

In order to obtain glasses appropriate to the thick film copper conductors, nine glasses based on both lead borosilicate and leadless borosilicate systems were made and the applicabilities of them were examined in conjunction with the requirements for thick film copper conductors. As the results, it was found that all the glasses are fitted to provide suitable sheet resistance, solderability and solder leach resistance to thick film copper conductors. However, it was turned out that only the lead borosilicate based glasses worked for getting usable aged adhesion strength of copper thick film to the alumina substrate, while copper conductor films made from the other glasses had poor aged adhesion strengths. Particularly cuprous oxide added lead borosilicate glass was considered as one of the most favorable glasses for manufacturing thick film copper conductors.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.208-208
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• 2008

Micro patterning of conductor line/space on LTCC green sheet in the LTCC module is an important process for miniaturization in 3D integrated circuits. This work presented the effect of inorganic binders on the microstructure, adhesion, electrical resistivity, shrinkage and line/space resolution, which is a part of study in photoimageable conductor paste. The photoimageable conductor paste contains silver powder, polymer binder, monomer, photo-initiator, UV absorber, and solvent. The inorganic binders were furnished with varied weight percentage of anorthite, diopside and MLS-62 glass frits from 0% to 7%. The Line/space sizes thus obtained was under 25 micron.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.118-119
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• 2017

The combined waterproofing method is an excellent method to overcome the disadvantages of the single waterproofing method by composing two or more materials to complement each other, but it is a method that can cause defects such as separation and peeling between materials due to the heterogeneity of the applied two materials. In order to improve this, in this study, we aimed to develop a technology for inducing chemical unification between materials through a urea reaction with a coating material applied on the lower side by laminating a nonwoven fabric treated with a modified amine on the back surface of the sheet material, The adhesion performance test was carried out with the presence or absence of denatured amine treated nonwovens as variables. As a result of the test, it was confirmed that the adhesion performance of the specimen to which the modified amin - treated nonwoven fabric was applied was improved by about 60% or more as compared with the specimens not having the denatured amine treated specimen.

• Journal of the Korean Wood Science and Technology
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• v.36 no.1
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• pp.45-53
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• 2008

The burning behaviors of board for flooring materials were investigated using cone calorimetry at an incident heat flux of $50kWm^{-2}$. Seven domestic flooring materials were used to observe the burning behavior of maximum heat release rate, total heat release and average heat release rate. The experimental data indicated that the medium density fiberboard (MDF) flooring had higher release rate than the other flooring materials. Also, the mass loss of MDF flooring was higher than the other floors. When measuring the smoke production from burning, PE fiberboard flooring and PVC Plastic Resin Sheet showed higher carbon monoxide and carbon dioxide yield than the others. The average smoke release of both carbon dioxide and carbon monoxide through specific extinction area was similar. Toxic smoke measurement from flooring materials were determined by the mouse stop motion, and the results indicated that MDF flooring contains more toxic material than the other flooring materials.