• Journal of Adhesion and Interface
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• v.20 no.1
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• pp.23-28
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• 2019

In this study, the micro- and nano-particles were used and their shapes were transferred into the polydimethylsiloxane (PDMS) film to fabricate the dry adhesives and their properties were investigated. The Cu nanoparticles of the sizes of 20 nm, 40 nm and 70 nm and the polymethylmethacrylate (PMMA) beads of the size of $5{\mu}m$ were used to transfer their images and the resultant properties of the dry adhesives were compared. The effects of particle size and materials on the mechanical property, tensile adhesion strength, light transmittance, surface morphology, water contact angle were studied. The dry adhesives obtained from the transfer process of Cu nanoparticles with the size of 20 nm resulted in the enhancement of tensile adhesion strength more than 300% compared to that of the bare PDMS. The formation of nanostructure of large surface area on the surface of the PDMS film by the Cu nanoparticles may responsible for the improvement. This study suggests that the use of nanoparticles during the fabrication of PDMS dry adhesives is easy and effective and could be applied to the fabrication of the medical patch.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.28 no.3
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• pp.165-170
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• 2022

If petroleum- derived plastic like a bio-based plastic was degradation, awareness like a global warming and environmental disasters will be decreased. Plastic film was produced by adding ferric ions according to concentration by using a pro-oxidant in polyolefin resin. Changes in tensile strength, elongation, and molecular weight were evaluated according to the UV irradiation time. Increasing the amount of ferric ions resulted in more significant declines of physical properties, and also resulted in greater changes in molecular weight. After 100 hours of UV irradiation, tensile strength declined significantly in the film containing pro-oxidant as compared to the control. A similar effect was also observed in terms of elongation. The film containing pro-oxidant showed a 73.8% decrease in molecular weight after 100 hours of UV irradiation. The appropriate use of pro-oxidant can not only degrade plastic film but also control the time of degradation at the petroleum-derived plastic films. Further studies are necessary to investigate the conditions of plastic film degradation.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.5
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• pp.339-346
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• 2023

The uncertainties of microstructural features affect the properties of materials. Numerous pores that are randomly distributed in materials make it difficult to predict the properties of the materials. The distribution of pores in cementitious materials has a great influence on their mechanical properties. Existing studies focus on analyzing the statistical relationship between pore distribution and material responses, and the correlation between them is not yet fully determined. In this study, the mechanical response of cementitious materials is predicted through an image-based data approach using a convolutional neural network (CNN), and the correlation between pore distribution and material response is analyzed. The dataset for machine learning consists of high-resolution micro-CT images and the properties (tensile strength) of cementitious materials. The microstructures are characterized, and the mechanical properties are evaluated through 2D direct tension simulations using the phase-field fracture model. The attributes of input images are analyzed to identify the spot with the greatest influence on the prediction of material response through CNN. The correlation between pore distribution characteristics and material response is analyzed by comparing the active regions during the CNN process and the pore distribution.

• International Journal of Highway Engineering
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• v.18 no.6
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• pp.97-104
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• 2016

OBJECTIVES : The objective of this research is to develop additives for the modification of Solvent DeAsphalting Residue (SDAR) to be used as pavement materials, and evaluate the performance of asphalt mixture manufactured using the SDAR modified by developed additives. METHODS : The SDAR generally consists of more asphaltenes and less oil components compared to the conventional asphalt binder, and hence, the chemical/physical properties of SDAR are different from that of conventional asphalt binder. In this research, the additives are developed using the low molecular oil-based plasticizer to improve the properties of SDAR. First, the chemical property of two SDARs is analyzed using SARA (saturate, aromatic, resin, and asphaltene) method. The physical/rheological properties of SDARs and SDARs containing additives are also evaluated based on PG-grade method and dynamic shear-modulus master curve. Second, various laboratory tests are conducted for the asphalt mixture manufactured using the SDAR modified with additives. The laboratory tests conducted in this study include the mix design, compactibility analysis, indirect tensile test for moisture susceptibility, dynamic modulus test for rheological property, wheel-tracking test for rutting performance, and direct tension fatigue test for cracking performance. RESULTS : The PG-grade of SDARs is higher than PG 76 in high temperature grades and immeasurable in low temperature grades. The dynamic shear modulus of SDARs is much higher than that of conventional asphalt, but the modified SDARs with additives show similar modulus compared to that of conventional asphalt. The moisture susceptibility of asphalt mixture with modified SDARs is good if, the anti-stripping agent is included. The performance (dynamic modulus, rutting resistance, and fatigue resistance) of asphalt mixture with modified SDARs is comparable to that of conventional asphalt mixture when appropriate amount of additives is added. CONCLUSIONS : The saturate component of SDARs is much less than that of conventional asphalt, and hence, it is too hard and brittle to be used as pavement materials. However, the modified SDARs with developed additives show comparable or better rheological/physical properties compared to that of conventional asphalt depending on the type of SDAR and the amount of additives used.

• Journal of Conservation Science
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• v.26 no.3
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• pp.335-340
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• 2010

Urethane resin applicable for the first transcription of historical site and transcription of soil layer were synthesized in order to replace the imported urethane resin, NS-10. Comparing to the NS-10, the urethane polymers showed similar penetration to wet soil and formed a stable layer of polyurethane during progress working the peeling off the polyurethane pre-product from epoxy surface of final product. The urethane resins used for the first transcription of historical site improved tensile strength, which is consistent with that of NS-10. In addition the urethane resin for transcription of soil layer was supplied with hardness that have a also same strong point as like NS-10. This property is advantage due to simplifying the transcription work of soil layer in backward. When we tested to the real ground soil as well as experimentation compressed soil with use these synthesis urethane resin, we ca get the satisfying result in penetration property and stability and these properties evaluated the resins as an advanced product serving better convenience for worker.

• International Journal of Highway Engineering
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• v.8 no.1 s.27
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• pp.15-23
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• 2006

Criteria of the current asphalt mix design, Marshall method, includes the stability and flow which are not related with field performance of HMA mixture, together with the air void, Void filled with asphalt (VFA) and/or Void of mineral Aggregate(VMA). In addition, the limits of stability and flow are satisfied in most cases, the Optimum asphalt content (OAC) is determined based on volumetric properties, such as the air void and/or VFA and/of VMA. Therefore, many researchers have sought mechanistic properties which can replace the stability and flow, making the designed mixture having potential for better field performance. This study initiated to develope a mix design by introducing two performance-related mechanistic properties, the deformation strengh and fracture energy, in place of the stability and flow of the Marshall method. The deformation strength $(S_D)$ from the Kim Test has a high correlation with rutting property and the fracture energy(FE) from the indirect tensile test represents the fatigue cracking property of asphalt mixture. Four types of asphalt mixture were prepared for examining possibility of using the suggested mix design method in comparison with current methods. The results showed that mechanical properties were reflected in determination of OAC with this suggested mix design, unlike the existing Marshall method.

• Journal of Applied Biological Chemistry
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• v.58 no.2
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• pp.145-151
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• 2015

Corn fiber protein (CFP) was extracted from corn wet-milling by-product, corn fiber. CFP films containing various plasticizers and cross-linking agents were prepared and their mechanical properties were determined. Among the plasticizers and cross-linking agents used in this study, the CFP film containing 2 g fructose and 0.03% cinnamaldehyde had the most appropriate physical property. In addition, the CFP films containing green tea extract (GTE) were prepared by incorporating different amounts (0, 0.5, 1.0, 1.5%) of GTE into the film-forming solution. Tensile strength, film solubility, and opacity of the CFP films increased with the addition of GTE, whereas elongation and water vapor permeability of the CFP/GTE films decreased compared to those of the control. The antioxidant activity of the CFP/GTE film was determined in terms of 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity. As a result, antioxidant activity of the films increased with increasing GTE concentration. Furthermore, antimicrobial activity against Escherichia coli O157:H7, Listeria monocytogenes, and Staphylococcus aureus increased with increasing GTE concentration. These results indicate that the incorporation of GTE could enhance antioxidant and antimicrobial activities of the CFP films.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.1
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• pp.55-61
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• 2015

Stretchable electrode materials are focused to apply to flexible device such as e-skin and wearable computer. Used as a flexible electrode, increase in electrical resistance should be minimalized under physical strain as bend, stretch and twist. Carbon black is one of candidates, for it has many advantages of low cost, simple processing, and especially reduction in resistivity with stretching. However electrical conductivity of carbon black is relatively low to be used for electrodes. Instead graphene is one of the promising electronic materials which have great electrical conductivity and flexibility. So it is expected that graphene added carbon black may be proper to be used for stretchable electrode. In this study, under stretching electrical property of graphene added carbon black composite electrode was investigated. Mechanical stretching induced cracks in electrode which means breakage of conductive path. However stretching induced aligned graphene enhanced connectivity of carbon fillers and maintained conductive network. Above all, electronic structure of carbon electrode was changed to conduct electrons effectively under stretching by adding graphene. In conclusion, an addition of graphene gives potential of carbon black composite as a stretchable electrode.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.4
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• pp.97-103
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• 2014

Among various lead-free solders, the Sn-58Bi solders have been considered as a highly promising lead-free solders because of its low melting temperature and high tensile strength. However, Sn-58Bi solder has the poor ductility. To enhance the mechanical property of Sn-58Bi solder, epoxy-enhanced Sn-58Bi solders have been studied. This study compared the microstructures and the mechanical properties of Sn-58Bi solder and Sn-58Bi epoxy solder with aging treatment. The solders ball were formed on the printed circuit board (PCB) with organic solderability preservative (OSP) surface finish, and then the joints were aged at 85, 95, 105 and $115^{\circ}C$ for up to 100, 300, 500 and 1000 hours. The shear test was conducted to evaluate the mechanical property of the solder joints. $Cu_6Sn_5$ intermetallic compound (IMC) layer grew with increasing aging time and temperature. The IMC layer for the Sn-58Bi epoxy solder was thicker than that for the Sn-58Bi solder. According to result of shear test, the shear strength of Sn-58Bi epoxy solder was higher than that of Sn-58Bi solder and the shear strength decreased with increasing aging time.

• Applied Chemistry for Engineering
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• v.31 no.3
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• pp.310-316
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• 2020

Terpene-modified phenolic resins were used to improve the tires wet traction related to the driving safety and also rolling resistance related to fuel efficiency. In this work, alpha-pinene, beta pinene, and delta limonene resins, which constitute different basic structures of terpene-modified phenolic resins, were individually added to the tread compounds of tires and their physical properties were compared with those of the alkyl phenol resin compounds. Alkyl phenolic resins showed no significant difference in tangent delta from terpene-modified phenolic resins at 0 ℃, which is related to wet traction, but showed higher tangent delta at 80 ℃, which is related to rolling resistance, indicating smaller fuel efficiency improvement effects. Among the terpene-modified phenolic resins, beta pinene one showed improved wet traction and fuel efficiency compared to those of other resins. Delta limonene resin showed the best wet traction improvement effect, and alkyl phenolic resins showed relatively high tensile strength and abrasion property. All terpene-modified resins exhibited better rolling resistance than those of alkyl phenolic ones so that they can be said to have better fuel efficiency improvement effects and also to improve other properties compared to those of blanks. Terpene-modified phenolic resins could be used when mixing tire compounds referring to the properties of the phenolic resins revealed in this work, which could result in preparing compounds with improved wet traction and rolling resistance.