• Journal of Adhesion and Interface
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• v.15 no.1
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• pp.9-13
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• 2014

The purpose of this work is to investigate the specific gravity, thermal, and mechanical property changes of polypropylene (PP)/mica composites before and after solid-state extrusion. On increasing the filler content, the specific gravity of the composites increased. The specific gravity of the oriented specimen containing filler in PP matrix is found to be much smaller than that of pre-specimen due to the formation of more microvoids. The presence of microvoids in the case of oriented composite specimen significantly affected the tensile and flexural properties of the composites. Both flexural strength and modulus of the composites showed maxima when the mica contents was 10 wt%, regardless of the orientation via solid state extrusion.

• Corrosion Science and Technology
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• v.21 no.5
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• pp.340-347
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• 2022

In this research, mixed metal oxide (TiO₂, RuO₂) coating was applied to grade 1 titanium as a bipolar plate for polymer electrolyte membrane fuel cell (PEMFC). Electrochemical experiments were carried out in an aqueous solution of pH 3 (H₂SO₄ + 0.1 ppm HF, 80 ℃) determined by DoE. The air was bubbled to simulate a cathode environment. Potentiodynamic polarization test revealed that corrosion current densities of the titanium substrate and MMO-coated specimen were 0.180 µA/cm² and 4.381 µA/cm², respectively. There was no active peak. After potentiostatic experiment, current densities of the titanium substrate and the MMO-coated specimen were 0.19 µA/cm² and 1.05 µA/cm², respectively. As a result of observing the surface before and after the potentiostatic experiment, cracked dried clay structures were observed without corrosion damage. Both the titanium substrate and the MMO-coated specimen could not satisfy the interfacial contact resistance suggested by the DoE. Thus, further research is needed before they could be applied as bipolar plates.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1030-1035
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• 2003

The nanoimprint lithography technology makes higher density of semiconductor device and larger capacity of storage media. In this technology the induced damage while detaching polymer pattern from mold should be minimized. In order to analyze the problem, the basic knowledge of adhesion between the polymer and the mold is required. In this study a contact experiment of polyisobutylene specimen with spherical steel tip and polyisobutylene bead tip was conducted using nano indenter. During the contact experiment with various loading rate under load control the contact behavior of viscoelastic material was measured, i.e., the load and displacement between the tip and the specimen were measured. The data was analyzed by HBK model to obtain the stress intensity factor of contact edge and the contact radius as a function of time. Also the adhesion energies between steel/polyisobutylene and polyisobutylene/polyisobutylene were obtained employing the analysis of the crack of viscoelastic material by Schapery.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.197-200
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• 2006

The bond characteristics of three different types of glass fiber reinforced polymer(GFRP) reinforcing bars with different surface deformations were studied experimentally. Each specimen consisted of a concrete prism, 150 by 150 mm on each edge, with the longer axis in the vertical direction. Two rebars were embedded in each specimen, perpendicular to the longer axis and parallel to and equidistant from the sides of the prism. In vertical direction, one rebar was located at 75 mm from the bottom of the prism, and the other 225 mm from the bottom. All testing procedures including specimens preparation, set-up of test equipments and measuring devices were made according to the recommendations of CSA Standard S806-02.It was found that the bottom reinforcements showed higher bond stress than that of the top rebars.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.30-33
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• 1994

This paper studies on the effect of DSC(Differential Scanning Calorimeter) analysis condition on the glass transition temperature of silica filled epoxy network polymer used for ultra-high voltage apparatus. The effects of temperature scanning rate specimen size and gas flow rate on measured glass transition temperature have been studied in order to select optimum thermal analysis condition.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.15-16
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• 2022

In order to examine the adhesion characteristics of road pavement according to environmental conditions, the freezing time of cement mortar and the adhesion performance between ice and pavement were evaluated depending on the presence or absence of polymer and water repellent. As a result of measuring the ice formation time, it was found that there was no delay when a polymer was added, but the complete freezing time was delayed when a water repellent was added. As a result of measuring the strength of ice adhesion, it was found that the bonding force between ice and the surface of the test body was greatly generated in the test body without water repellent. In the case of a test specimen to which a water repellent was added, it was found that the bonding strength between the test specimen surface and ice was reduced.

• Polymer(Korea)
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• v.27 no.2
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• pp.113-119
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• 2003

The thermal properties and crystallization behaviors of poly(ethylene terephthalate) (PET) were investigated by controlling the annealing conditions of PET sample, such as relative humidity, temperature, and time. The variations of moisture content, glass transition temperature ($T_g$) and cold crystallization temperature ($T_{\propto}$) were examined after annealing the PET sample. Subsequently crystallization process was performed with the annealed PET specimen, and then the degree of crystallinity and heat distortion temperature (HDT) of variously crystallized PET specimen were examined. Residual stress relaxation in the injection molded PET sample after annealing was also observed through polarized films. Moisture content in the PET specimen increased up to 6000 ppm with increasing the relative humidity, temperature, and time of annealing. $T_g$ and $T_{\propto}$ of the annealed PET specimen decreased with increasing moisture content. The degree of crystallinity increased as increasing moisture content in the PET specimen. However for same moisture content, the degree of crystallinity varied with annealing conditions. The relaxations of residual stress in the PET sample differed from annealing conditions, and the maximum degree of crystallinity increased with decreasing residual stress in the PET sample.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.93-96
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• 2001

Structural polymer composites are susceptible to damage in the form of cracks, which form deep within the structure where detection is difficult and repair is almost impossible. A recent methodology for the damage repair of polymer composites using the self-healing technique is reported. The polymerization of the healing agent is triggered by contact with an embedded catalyst, being necessary to damage repair of polymer composites. For this purpose, the self-healing concept is introduced and the manufacturing process of microcapsule with the healing agent is briefly described. The polymerization between the healing agent and the catalyst is verified by the use of ESEM and IR spectroscopy. Finally the efficiency of the self-healing technique is investigated by measuring the critical load of TDCB specimen.

• Journal of the Korean Society of Safety
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• v.31 no.4
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• pp.82-89
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• 2016

In this paper, various of experiments were performed for checking the usefulness of Pozzolan Inorganic Polymer(PIP) Waterproof Admixture. The results of the experiment enabled to set the optimum mixture ratio of PIP waterproof admixture as 3.5%. Then, the test specimen mixed with PIP waterproof admixture was produced and consider whether meeting the quality standard of waterproofing admixture for concrete (KS F 4926) From the results, all the items such as mechanical properties and durability were meet the quality standard of KS. The PIP waterproof admixture concrete shows the high resistance of absorption, permeability and chloride ion penetration thanks to its internal components such as siliceous powder, zinc stearate and dispersive polymer.

• Journal of The Korean Society of Agricultural Engineers
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• v.50 no.5
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• pp.29-37
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• 2008

Stress-strain relation and stress block parameters of polymer concrete flexural compression members were experimentally investigated. For these purposes, a series of C-shaped polymer concrete specimens subjected to axial compressive load was tested. Based on the test results, we proposed an equation by which the stress-strain relation of polymer concrete can be predicted. In this model, we took account the slope of descending branch beyond the peak stress point of single curve. The proposed equation was numerically integrated to compute the rectangular stress block parameters. Computed ${\beta}_1$ was greater than the values prescribed in ACI 318 Code for cement concrete, and $\gamma$ was about 0.85 that is similar to the value regulated in the ACI.