• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.1805-1808
• /
• 2006

In this paper, we describe a versatile use of fullerene(C60) as a charge transporting material for organic light-emitting diodes. The use of fullerene as a buffer layer for an anode, a doping material for hole transport layer, and an electron transport layer was investigated. Fullerene improved the hole injection from an anode to a hole transport layer by lowering the interfacial energy barrier and enhanced the lifetime of the device as a doping material for a hole transport layer. In addition, it was also effective as an electron transporting material to get low driving voltage in the device.

• Archives of Pharmacal Research
• /
• v.2 no.2
• /
• pp.85-88
• /
• 1979

Data on the solubility of p-hydroxy-benzoate in amide-water cosolvent system and surface tension of the binary amide-water cosolvents are analyzed in terms of the possible mechanism for cosolvency. The results of the study suggest that strong partitioning of the alkylated amides to the ester surface, thus reducing the hydrophobic interface within the system, nay account for much of the cosolvency phenomena observed in these systems.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2016.05a
• /
• pp.74-75
• /
• 2016

• Bulletin of the Korean Chemical Society
• /
• v.34 no.7
• /
• pp.2029-2035
• /
• 2013

The impact of phosphorous (P)-doping on the electrochemical performance and surface chemistry of soft carbon is investigated by means of galvanostatic cycling and ex situ X-ray photoelectron spectroscopy (XPS). P-doping plays an important role in storing more Li ions and discernibly improves reversible capacity. However, the discharge capacity retention of P-doped soft carbon electrodes deteriorated at $60^{\circ}C$ compared to non-doped soft carbon. This poor capacity retention could be improved by vinylene carbonate (VC) participating in forming a protective interfacial chemistry on soft carbon. In addition, the effect of P-doping on exothermic thermal reactions of lithiated soft carbon with electrolyte solution is discussed on the basis of differential scanning calorimetry (DSC) results.

• Nuclear Engineering and Technology
• /
• v.3 no.1
• /
• pp.21-31
• /
• 1971

The part of the work of plastic deformation of metal goes into the changes in the total surface free energy. This contribution is dependent on the specific surface free energy, which is affected by the environment. Based on thermodynamical approach, volume constancy requirement and adsorption induced two distinct dislocation interaction mechanisms for strengthening or weakening of metals at surface, theoretical derivation has been made to show that the environmental contribution on the strain hardening, the stress and the energy required for plastic deformation can be expressed in terms of solid surface tension in vacuum (${\gamma}$$_{s}$), interfacial tension (${\gamma}$$_{se}$ ), surface dislocation density ($\rho$$_{s}$), internal dislocation density ($\rho$$_{i}$) and fraction of surface site uncoverage (f). On the basis of theoretical derivation, the various mechanical behaviours under different environments are predicted.d.d.

• Korean Journal of Materials Research
• /
• v.31 no.5
• /
• pp.272-277
• /
• 2021

Owing to its low cost, easy fabrication process, and good ionic properties, aqueous supercapacitors are under strong consideration as next-generation energy storage devices. However, the limitation of the current collector is its poor electrochemical stability, leading to low energy storage performance. Therefore, a reasonable design of the current collector and the acidic electrolyte is a necessary, as well as interfacial engineering to enhance the electrochemical performance. In the present study, graphite foil, with excellent electrochemical stability and good electrical properties, is suggested as a current collector of aqueous supercapacitors. This strategy results in excellent electrochemical performance, including a high specific capacitance of 215 F g^-1 at a current density of 0.1 A g^-1, a superior high-rate performance (104 F g^-1 at a current density of 20.0 A g^-1), and a remarkable cycling stability of 98 % at a current density of 10.0 A g^-1 after 9,000 cycles. The superior energy storage performance is mainly ascribed to the improved ionic diffusion ability during cycling.

• Geomechanics and Engineering
• /
• v.16 no.4
• /
• pp.385-397
• /
• 2018

This study evaluates the interfacial properties of composite specimens consisting of shotcrete and sprayed waterproofing membrane. Two different membrane prototypes were first produced and tested for their waterproofing ability. Then composite specimens were prepared and their interfacial properties assessed in direct shear and uniaxial compression tests. The direct shear test showed the peak shear strength and shear stiffness of the composites' interface decreased as the membrane layer became thicker. The shear stiffness, a key input parameter for numerical analysis, was estimated to be 0.32-1.74 GPa/m. Shear stress transfer at the interface between the shotcrete and membrane clearly emerged when measuring peak shear strengths (1-3 MPa) under given normal stress conditions of 0.3-1.5 MPa. The failure mechanism was predominantly shear failure at the interface in most composite specimens, and shear failure in the membranes. The uniaxial compression test yielded normal stiffness values for the composite specimens of 5-24 GPa/m. The composite specimens appeared to fail by the compressive force forming transverse tension cracks, mainly around the shotcrete surface perpendicular to the membrane layer. Even though the composite specimens had strength and stiffness values sufficient for shear stress transfer at the interfaces of the two shotcrete layers and the membrane, the sprayed waterproofing membrane should be as thin as possible whilst ensuring waterproofing so as to obtain higher strength and stiffness at the interface.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2002.05a
• /
• pp.109-113
• /
• 2002

Interfacial and electrical properties for the carbon fiber reinforced epoxy-amine terminated (AT) PEI composites were performed using microdroplet test and electrical resistance measurements. As AT PEI content increased, the fracture toughness of epoxy-AT PEI matrix increased, and IFSS was improved due to the improved toughness and energy absorption mechanisms of AT PEI. The microdroplet in the carbon fiber/neat epoxy composite showed brittle microfailure mode. At 15 wt% AT PEI content, ductile microfailure mode appeared because of improved fracture toughness. After curing, the changes of electrical resistance (ΔR) with increasing AT PEI content increased gradually because of thermal shrinkage. The matrix fracture toughness was correlated to IFSS, TEC and electrical resistance. In cyclic strain test, the maximum stress and their slope of the neat epoxy case were higher than those of 15 wt% AT PEI. The results obtained from electrical resistance measurements under curing process and reversible stress and strain were consistent well with matrix toughness properties.

• Textile Coloration and Finishing
• /
• v.27 no.1
• /
• pp.18-26
• /
• 2015

para-aramid fibers were treated by atmosphere air plasma to improve the interfacial adhesion. The wettability of plasma-treated aramid fiber was observed by means of dynamic contact angle surface free energy measurement. Surface roughness were investigated with the help of scanning electron microscopy and atomic force microscopy. The tensile test of aramid fiber roving was carried out to determine the effect of plasma surface treatments on the mechanical properties of the fibers. A pull-out force test was carried out to observe the interfacial adhesion effect with matrix material. It was found that surface modification and a chemical component ratio of the aramid fibers improved wettability and adhesion characterization. After oxygen plasma, it was indicated that modified the surface roughness of aramid fiber increased mechanical interlocking between the fiber surface and vinylester resin. Consequently the oxygen plasma treatment is able to improve fiber-matrix adhesion through excited functional group and etching effect on fiber surface.

• Korean Journal of Materials Research
• /
• v.26 no.12
• /
• pp.751-756
• /
• 2016

Graphite was diffusion-bonded by hot-pressing to W-25Re alloy using a Ti interlayer. For the joining, a uniaxial pressure of 25 MPa was applied at $1600^{\circ}C$ for 2 hrs in an argon atmosphere with a heating rate of $10^{\circ}C\;min^{-1}$. The interfacial microstructure and elemental distribution of the W-25Re/Ti/Graphite joints were analyzed by scanning electron microscopy (SEM). Hot-pressed joints appeared to form a stable interlayer without any micro-cracking, pores, or defects. To investigate the high-temperature stability of the W-25Re/Ti/Graphite joint, an oxy-acetylene torch test was conducted for 30 seconds with oxygen and acetylene at a 1.3:1 ratio. Cross-sectional analysis of the joint was performed to compare the thickness of the oxide layer and its chemical composition. The thickness of W-25Re changed from 250 to $20{\mu}m$. In the elemental analysis, a high fraction of rhenium was detected at the surface oxidation layer of W-25Re, while the W-25Re matrix was found to maintain the initial weight ratio. Tungsten was first reacted with oxygen at a torch temperature over $2500^{\circ}C$ to form a tungsten oxide layer on the surface of W-25Re. Then, the remaining rhenium was subsequently reacted with oxygen to form rhenium oxide. The interfacial microstructure of the Ti-containing interlayer was stable after the torch test at a temperature over $2500^{\circ}C$.