• Journal of Industrial and Engineering Chemistry
• /
• v.67
• /
• pp.417-428
• /
• 2018

In this study, we fabricated hierarchically self-assembled thin films composed of graphene oxide (GO) sheets and gold nanoparticles (Au NPs) using the Langmuir-Blodgett (LB) and Langmuir-Schaefer (LS) techniques and investigated their gas-sensing performance. First, a thermally oxidized silicon wafer ($Si/SiO_2$) was hydrophobized by depositing the LB films of cadmium arachidate. Thin films of ligand-capped Au NPs and GO sheets of the appropriate size were then sequentially transferred onto the hydrophobic silicon wafer using the LB and the LS techniques, respectively. Several different films were prepared by varying the ligand type, film composition, and surface pressure of the spread monolayer at the air/water interface. Their structures were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), and their gas-sensing performance for $NH_3$ and $CO_2$ was assessed. The thin films of dodecanethiol-capped Au NPs and medium-sized GO sheets had a better hierarchical structure with higher uniformity and exhibited better gas-sensing performance.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2022.04a
• /
• pp.43-44
• /
• 2022

In this study, the optimum amount of chloride ions is used to collaborate with hybrid corrosion inhibitor for carbon steel rebar treatment in simulated pore concrete (SCP) solution is discovered. The corrosion inhibition performance of hybrid inhibitors is carried on by open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PP). The highest corrosion inhibition resistance is found in case of LP-C2 after 240 h exposure. Surface studies including scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used to figure out the surface morphology of the steel rebar treated with hybrid inhibitors in order to collaborate well with electrochemical studies. Anodic type inhibition action was confirmed by potentiodynamic polarization study.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2021.11a
• /
• pp.65-66
• /
• 2021

In this study, the optimum amount of hybrid inhibitors i.e. L-Arginine (LA) and sodium phosphate tribasic dodecahydrate (SP), applied for carbon steel rebar in simulated pore concrete (SCP) solution contaminated with 3.5 wt.% NaCl, was discovered. The corrosion inhibition performance of hybrid inhibitors was investigated by open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization. The highest corrosion inhibition efficiency was found as 99.52% corresponding to 2% LA and 0.25% SP after 210 h exposure. Anodic type inhibition action was confirmed by potentiodynamic polarization study. Surface studies including scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used to figure out the surface morphology of the steel rebar treated with hybrid inhibitors in order to collaborate with electrochemical studies.

• Journal of Radiation Industry
• /
• v.4 no.4
• /
• pp.335-339
• /
• 2010

In this study, the surface of polyimide (PI) films was modified using ion implantation to enhance its adhesion to a deposited copper (Cu) layer. The surfaces of the PI films were implanted with 150 keV $Xe^+$ ions at fluences varying from $1{\times}10^{14}$ to $1{\time}10^{16}ions\;cm^{-2}$. The Cu layers were then deposited on the implanted PI. The surface properties of the implanted PI film were investigated based on the contact angle measurements, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Furthermore, the adhesive strength between the deposited Cu layer and PI film was estimated through a scratch test using a nanoindenter. As a result, the surface environment of the PI film was changed by the ion implantation, which could have a significant effect on the adhesion between the deposited Cu layer and the PI.

• Korean Journal of Materials Research
• /
• v.23 no.6
• /
• pp.322-328
• /
• 2013

The relationship the between electrical properties and surface roughness (Ra) of a wet-etched silicon wafer were studied. Ra was measured by an alpha-step process and atomic force microscopy (AFM) while varying the measuring range $10{\times}10$, $40{\times}40$, and $1000{\times}1000{\mu}m$. The resistivity was measured by assessing the surface resistance using a four-point probe method. The relationship between the resistivity and Ra was explained in terms of the surface roughness. The minimum error value between the experimental and theoretical resistivities was 4.23% when the Ra was in a range of $10{\times}10{\mu}m$ according to AFM measurement. The maximum error value was 14.09% when the Ra was in a range of $40{\times}40{\mu}m$ according to AFM measurement. Thus, the resistivity could be estimated when the Ra was in a narrow range.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.278-278
• /
• 2012

최근 폴리이미드(Polyimide) 고분자 물질을 기판으로 하는 플렉시블 전자소자 구현에 관한 연구가 활발히 진행 되고 있다. 폴리이미드는 수분 흡수율이 1% 이하인 소수성 물질로서 폴리이미드 기판 위 전극 형성에 있어 전극 물질이 분리되는 현상이 발생하게 된다. 따라서 본 연구에서는 소수성의 표면 성질을 갖는 폴리이미드 기판의 Asher 처리를 통한 표면 최적화에 대한 실험을 진행하였다. 유리기판 위에 액상 폴리이미드를 ${\sim}10{\mu}m$ 두께로 Spin coating 한 후 $120^{\circ}C$ hot plate에서의 soft bake와 $200^{\circ}C$, $320^{\circ}C$의 furnace에서의 단계적 cure 과정을 통해 표면의 defect을 최소화하였다. Microwave Asher 장비를 이용하여 폴리이미드 막에 10초, 15초, 20초 동안 asher 처리를 한 후 Atomic Force Microscopy (AFM) 장비로 시간에 따른 폴리이미드 기판 표면의 변화를 확인하였다. AFM 확인 결과 10 초의 공정 조건에서 가장 우수한 표면 morphology를 보였으며, 이는 표면의 탄소와 이물질을 제거하기 위해 사용되는 asher 처리 시간이 상대적으로 증가함에 따라 폴리이미드 막의 탄소 성분이 제거 되면서 표면의 형상이 최적화 이상으로 변화하기 때문이다. 본 실험은 폴리이미드를 기반으로 하는 플렉시블 전자소자 구현에 있어 전극 및 소자 제작에 크게 기여할 것으로 판단된다.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.50 no.5
• /
• pp.211-215
• /
• 2001

SBT thin films were etched at different content of $Cl_2$ in $Cl_2$/Ar or $Cl_2/N_2$(80%). As $Cl_2$ gas increased in $Cl_2$/Ar or $Cl_2/N_2$ gas plasma. the etch rate decreased. The result indicates that physical puttering of charged particles is dominant to chemical reaction in etching SBT thin films. To evaluate the etching mechanism of SBT thin films, x-ray photoelectron to chemical reaction in etching SBT thin films. To evaluate the etching mechanism of SBT thin films, x-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS) and atomic force microscopy (AFM) were carried out. From the result of AFM, the rms values of etched samples in Ar only or $Cl_2$ only plasma were higher than that of as-deposited, $Cl_2$/Ar and $Cl_2/N_2$ plasma. This can be illustrated by a decrease of Bi content of nonvolatile etching products (Sr-Cl and Ta-Cl), which are revealed by XPS and SIMS.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.11a
• /
• pp.192-195
• /
• 2003

There has been increasing interest in the applications of synthesized molecules of nanometer scale in recent years due to their potential utilization in various fields such as biology, optoelectronics and molecular electronics. In this study, the terpyridine-platinum (II) complex on the periphery of the dendritic carbosilane has been prepared from the reaction of Pt(COD)Cl2 and the 4'-functionalized-(2,2':6',2"-terpyridine) on dendrimers. The self-assembly process was carried out to obtain indivially dispersed dendrimer on Au (111) substrate. It was found that STM was unsuitable to obtain a obvious image of dendrimers. Tapping-mode atomic force microscopy(AFM) has been used to investigate the shape and size of dendrimers individually dispersed on Au (111)substrate. As a result, the imaged single dendrimer show that dendrimer is dome shaped and its size can be measured by tapping-mode AFM.

• Journal of Periodontal and Implant Science
• /
• v.48 no.6
• /
• pp.373-382
• /
• 2018

Purpose: The aim of this study was to evaluate the effects of various prophylactic treatments of titanium implants on bacterial biofilm formation, correlating surface modifications with the biofilms produced by Pseudomonas aeruginosa PAO1, Staphylococcus aureus, and bacteria isolated from saliva. Methods: Pure titanium disks were treated with various prophylactic procedures, and atomic force microscopy (AFM) was used to determine the degree to which surface roughness was modified. To evaluate antibiofilm activity, we used P. aeruginosa PAO1, S. aureus, and saliva-isolated Streptococcus spp., Bacteroides fragilis, and Staphylococcus epidermidis. Results: AFM showed that the surface roughness increased after using the air-polishing device and ultrasonic scaler, while a significant reduction was observed after using a curette or polishing with Detartrine ZTM (DZ) abrasive paste. In addition, we only observed a significant (P<0.01) reduction in biofilm formation on the DZ-treated implant surfaces. Conclusion: In this study, both AFM and antibiofilm analyses indicated that using DZ abrasive paste could be considered as the prophylactic procedure of choice for managing peri-implant lesions and for therapy-resistant cases of periodontitis.

• Tribology and Lubricants
• /
• v.18 no.4
• /
• pp.260-266
• /
• 2002

In this study, the effects of oxide layer farmed on the wear tracks of TiN coated silicon wafer on friction and wear characteristics were investigated. Silicon wafer was used for the substrate of coated disk specimens, which were prepared by depositing TiN coating with 1 ${\mu}{\textrm}{m}$ in coating thickness. AISI 52100 steel ball was used fur the counterpart. The tests were performed both in air for forming oxide layer on the wear track and in nitrogen to avoid oxidation. This paper reports characterization of the oxide layer effects on friction and wear characteristics using X-ray diffraction(XRD), Auger electron spectroscopy(AES), scanning electron microscopy (SEM) and multi-mode atomic force microscope(AFM).