• Journal of Surface Science and Engineering
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• v.57 no.3
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• pp.221-224
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• 2024

The 304 stainless steel has good corrosion resistance, so it is used in various industries. However, in an environment like seawater, stainless steel can be damaged by chloride ions, resulting in surface corrosion such as pitting and crevice corrosion. Electropolishing is a technique that smooths the surface and creates a passivation layer that can resist corrosion. In this study, electropolishing was applied as a surface finish to increase the smoothness of the metal surface and its corrosion resistance. We confirmed the topology of the electropolished surface of stainless steel by optical microscope and evaluated the corrosion resistance characteristics of electropolished stainless steel through a potentiodynamic experiment.

• Proceedings of the Korean Vacuum Society Conference
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• 2001.02a
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• pp.219-219
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• 2001

• Proceedings of the Korean Vacuum Society Conference
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• 2008.02a
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• pp.312-312
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• 2008

• Proceedings of the Korean Vacuum Society Conference
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• 2004.08a
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• pp.146-146
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• 2004

• Proceedings of the Korean Vacuum Society Conference
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• 2002.06a
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• pp.165-165
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• 2002

• Journal of Surface Science and Engineering
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• v.54 no.1
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• pp.1-11
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• 2021

Porous dendrite structure AuCu alloy was formed using a hydrogen bubble template (HBT) technique by electroplating to improve the catalytic performance of gold, known as an excellent oxygen reduction reaction (ORR) catalyst in alkaline medium. The rich Au surface was maximized by selectively electrochemical etching Cu on the AuCu dendrite surface well formed in a leaf shape. The catalytic activity is mainly due to the synergistic effect of Au and Cu existing on the surface and inside of the particle. Au helps desorption of OH- and Cu contributes to the activation of O2 molecule. Therefore, the porous AuCu dendrite alloy catalyst showed markedly improved catalytic activity compared to the monometallic system. The porous structure AuCu formed by the hydrogen bubble template was able to control the size of the pores according to the formation time and applied current. In addition, the Au-rich surface area increased by selectively removing Cu through electrochemical etching was measured using an electrochemical calculation method (ECSA). The results of this study suggest that the alloying of porous AuCu dendrites and selective Cu dissolution treatment induces an internal alloying effect and a large specific surface area to improve catalyst performance.

• Bulletin of the Korean Chemical Society
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• v.8 no.3
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• pp.158-161
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• 1987

A Series of hydrophilic-hydrophobic copolymeric surfaces of 2-hydroxyethyl methacrylate (HEMA) and various alkyl methacrylate (RMA) have been prepared by in-situ solution copolymerization using a redox radical initiator. Contact angles of various probing fluids on the polymeric surfaces were determined in air (hydrophobic environment) and under water (hydrophilic environment). From contact angle data, the dispersive interaction contribution (${\gamma}^d_s$) and the polar contribution (${\gamma}^p_s$) to the total surface free energy (${\gamma}^d_s$) and interfacial energetic quantities (e.g., water-polymer, liquid-polymer interface, etc.) were estimated by surface and interface physicochemical theory. From the comparison of surface energetic components between hydrophobic and hydrophilic media, it is found that surface and interface energetic components of polymeric surface as a representative low-energy surface are highly dependent on environmental fluids. Also, from the correlation between interfacial energetic results and surface energetic criterion of biocompatibility, we found that HEMA/BMA, HEMA/HMA copolymer systems are in the region of biocompatibility.

• Proceedings of the Korean Vacuum Society Conference
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• 2001.07a
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• pp.70-70
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• 2001

• Journal of Korean Academy of Dental Administration
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• v.7 no.1
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• pp.50-55
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• 2019

The purpose of this study was to compare the number of bacteria before and after the use of surface disinfectants, demonstrate the bactericidal effect of surface disinfectants, and emphasize on the importance of surface disinfectants by recognizing the importance of infection control in dentistry. Chlorhexidine, hydrogen peroxide, ethanol, and chemical disinfectants are commonly used in dentistry. NaOCl was selected as the experimental group, and the bacterium test results obtained by comparing the table without surface sterilization as a control group showed that all disinfectants had an effective bactericidal effect (p<0.05). In the growth inhibition test comparing the experimental and control groups, all results were 100%, proving the effectiveness of surface disinfectants. The results showed that all surface disinfectants preferred and used by medical institutions were effective. Therefore, all surface disinfectants used in the experimental group were effective for surface disinfection for infection control. Dental clinicians should be aware of the necessity of disinfection of surfaces, such as table, chairs, and unit chairs, and make an active effort to ensure that both clinicians and patients are safe from infection.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.170.1-170.1
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• 2016

$Bi_2Te_3$ has long been studied for its excellent thermoelectric characteristics. Recently, this material has been known as a topological insulator (TI). The surface states within the bulk band gap of a TI, which are protected by the time reversal symmetry, contribute to the conduction at the surface, while the bulk is in insulating state. In contrast to the bulk defects tuning the chemical potential to the Dirac energy, the native defects near the surface are expected not to change the shape of the Fermi surface and the related spin structure. Using scanning tunneling microscopy (STM), we have systematically characterized surface or near surface defects in p- and n- doped $Bi_2Te_3$, and identified their structure by first principles calculations. In addition, bias-polarity dependences of STM images revealed the electron donor/acceptor nature of each defect. A detailed theoretical study of the surface states near the Dirac energy reveals the robustness of the Dirac point, which verifies the effectiveness of the disturbance on the backscattering from various kinds of defects.