• 한국분무공학회지
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• 제17권1호
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• pp.20-26
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• 2012

Inkjet printing is one of the direct writing technologies and is able to form a pattern onto substrate by dispensing droplets in desired position. Also, by inkjet technology manufacturing time and production costs can be reduced, and procedures can be more efficient. To form a metal pattern, it must be harmonized with conductive nano ink, printing process, sintering, and surface treatment. In this study, micro patterning of conductive line has been investigated using the piezoelectric printhead driven by a bipolar voltage signal is used to dispense $20-40{\mu}m$ diameter droplets and silver nano ink which consists of 50 nm silver particles. In addition, hydrophobic treatment of surface, overlap printing techniques, and sintering conditions with changing temperature and times to achieve higher conductivity.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.24-24
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• 2018

One of the challenges in tissue engineering is the design of optimal biomedical scaffolds, which can be governed by topographical surface characteristics, such as size, shape, and direction. Of these properties, we focus on the effects of nano - to micro - sized hierarchical surface. To fabricate the hierarchical surface structure on poly(${\varepsilon}$-caprolactone) (PCL) film, we employed a nano/micro-casting technique (NCT) and modified plasma process. The micro size topography of PCL film was controlled by sizes of the micro structures on lotus leaf. Also, the nano-size topography and hydrophilicity of PCL film were controlled by modified plasma process. After the plasma treatment, the hydrophobic property of the PCL film was significantly changed into hydrophilic property, and the nano-sized structure was well developed, as increasing the plasma exposure time and applied power. The surface properties of the modified PCL film were investigated in terms of initial cell morphology, attachment, and proliferation using osteoblast-like-cells (MG63). In particular, initial cell attachment, proliferation and osteogenic differentiation in the hierarchical structure were enhanced dramatically compared to those of the smooth surface.

• 한국염색가공학회지
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• 제20권6호
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• pp.26-34
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• 2008

Wool fabric having high moisture content were treated with fluorocarbon-based water and oil repellent finishing agents by pad-dry-cure system. Three types of finishing agents which were regular-type or nano-type were adapted to compare the surface chemical composition, water and oil repellent property, crease recovery angle, and durability to repeated laundering. From the surface chemical compositions resulted by ESCA and C1s curve-fitting, it was shown that the regular-type finishing agent were easily taken off from the finished wool fabrics after repeated laundering. On the other hand, the fluoroalkyl groups of nano-type finishing agents turned round from fabric surface to fiber internal after repeated laundering. The water repellency of the wool fabrics treated with regular-type agent had a little changes according to the treatment condition changes and sharply decreased with repeated laundering. However, these values when treated with nano-type agents increased with the concentration and cure temperature and were maintained after 20 times laundering. The wool fabrics treated with nano-type agent had a great oil repellency irrespective of treatment conditions. Furthermore, the wrinkle recovery values of the wool fabrics treated with nano-type agents were higher than those of the fabrics treated with regular-type agent and were unchanged after 20 times laundering.

• Nano
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• 제13권10호
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• pp.1850120.1-1850120.9
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• 2018

Two-dimensional poly(dimethylsiloxane) (PDMS) films with wavy patterns were studied in order to investigate reversible and irreversible wetting effects. Pre-strained, surface oxidized layers of PDMS were used to form relieved wavy geometries, on which hydrophobic functionalization was carried out in order to produce irreversible wetting effects. Wavy-patterned PDMS films showed time-dependent reversible wetting effects. The degree of surface wettability could be tuned by the choice of wavy groove geometries. And the groove geometries were controlled via $O_2$ plasma treatment and mechanical pre-straining. The pre-strained, buckled PDMS films were applied to the fabrication of hydrophobic polystyrene nano-patterns using colloidal self-assembly, where the colloids were arrayed in two-dimensional way. The wavy polystyrene films were found to be more hydrophobic relative to flat polystyrene films. The grooving methodology used in this study could be applied to enhancing the hydrophobicity of other types of polymeric thin films, eliminating the need for chemical treatment.

• 한국결정성장학회지
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• 제16권3호
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• pp.106-111
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• 2006

The objective of this paper is to compare the surface features of two kinds of nano-porous activated carbon fiber (NPACF) treated with potassium and the variation of their properties by phosphoric acid pre-treatment. X-ray diffraction (XRD) patterns indicate that NPACF containing potassium species show better performance for potassium and potassium salts by pre-treatment with phosphoric acid. In order to present the causes of the differences in surface properties and specific surface area after the samples were treated with phosphoric acid, pore structure and surface morphology are investigated by adsorption analysis and SEM. For the chemical composition microanalysis for potassium loading of the NPACF pre-treated with phosphoric acid, samples were analyzed by EDX. Finally, the type and quality of oxygen groups are determined from the method proposed by Boehm.

• Journal of Ceramic Processing Research
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• 제20권6호
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• pp.589-596
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• 2019

Pigments with minute particle sizes, such as carbon black (CB) and pigment red 48:2 (P.R.48:2), are the most important types of pigment and have been widely used in many industrial applications. However, minute particles have large surface areas, high oil absorption and low surface energy. They therefore tend to be repellent to the vehicle and lose stability, resulting in significant increases in viscosity or reaggregation in the vehicle. Therefore, finding the best way to improve the dispersion properties of minute particle size pigments presents a major technical challenge. In this study, minute particle types of CB and P.R.48:2 were treated with nitrogen gas plasma generated via radio frequency-plasma enhanced chemical vapor deposition (RF-PECVD) to increase the dispersion properties of minute particles in deionized (DI) water. The morphologies and particle sizes of untreated and plasma treated particles were evaluated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The average distributions of particle size were measured using a laser particle sizer. Fourier transform infrared spectroscopy was carried out on the samples to identify changes in molecular interactions during plasma processing. The results of our analysis indicate that N2 plasma treatment is an effective method for improving the dispersibility of minute particles of pigment in DI water.

• 한국전기전자재료학회논문지
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• 제25권1호
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• pp.58-61
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• 2012

In our report a relatively simple process for fast nano-texturing of p-type(100) CZ- silicon surface using silver catalyzed wet chemical etching in aqueous hydrofluoric acid (HF) and hydrogen peroxide solution($H_2O_2$) at room temperature. The wafers were saw-damaged by NaOH(6 wt%) at $60^{\circ}C$ for 150s. To obtain a nano-structured black surface, a thin layer of silver with thickness of 1 - 10 nm was deposited on the surfaces by evaporation system. After this process the samples were etched in HF : $H_2O_2$ : $H_2O$ = 1:5:10 at room temperature for 80s - 220s. Due to the local catalytic of the Ag clusters, this treatment results in the nano-scale texturing on the surface. This resulted in average reflectance values less than 9% after the silver on the surface of the wafers were removed.

• 폴리머
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• 제38권3호
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• pp.391-396
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• 2014

고분자 마이크로니들은 몰딩 공정으로 쉽고 저렴하게 생산할 수 있지만 3차원 고분자 마이크로 구조체에 수용액 기반의 약물 코팅은 어려움이 있다. 2차원 형태의 평면 금속 마이크로니들에 약물을 코팅한 기존의 코팅 마이크로니들과 비교하여 볼 때 3차원 구조의 고분자 마이크로니들은 코팅 면적이 2배 넓고 단위면적당 마이크로니들의 수를 크게 증가시킴으로써 두 배 이상의 약물을 경피를 통해 전달할 수 있다. 증점제와 계면활성제 첨가 방법의 경우 2차원의 평면에는 균일한 코팅을 얻을 수 있었지만 3차원 구조의 고분자 마이크로니들 표면에서는 만족할 코팅을 얻지 못했다. 하지만, 고분자 마이크로니들 표면을 금속 코팅 혹은 UV/ozone으로 처리한 경우 3차원의 마이크로 니들 표면에 만족할 코팅을 얻을 수 있었으나 금속 코팅의 경우 피부에 찌르고 제거하는 과정에서 금속이 피부 안에 남는 안전성 문제가 있어 UV/ozone을 최종 표면 처리 방법으로 선정하였다. 이렇게 처리한 고분자 마이크로니들 표면에 calcein이 첨가된 코팅물질로 코팅된 마이크로니들은 15분 이상의 피부 투여로 코팅물질을 성공적으로 진피층까지 전달할 수 있었다.

• 한국표면공학회지
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• 제57권2호
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• pp.98-104
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• 2024

In order to overcome the urban heat island effect, highly functional paint is attracting attention as a promising means by shielding heat on the structure (building) surface. When a paint was prepared containing nano-sized silica particles, the heat-insulating performance was relatively higher than that of paints with other sizes. In addition, developed paints showed enhanced properties such as chemical resistance and abrasion resistance test because of the presence of nano-sized silica included in functional paint.

• 대한기계학회논문집A
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• 제38권10호
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• pp.1117-1123
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• 2014

본 연구는 균열 치유 물질로 알려진 $SiO_2$ 나노 콜로이드의 첨가량을 달리한 $Si_3N_4$를 소결하여, 경면 연마한 시험편 표면에 $SiO_2$ 나노 콜로이드를 코팅하여 1273 K, 공기중에서 1시간 균열치유 처리하였다. 그 후, 마모시험편은 1073, 1273 및 1573 K에서 10분간 열처리하여 시험을 실시하였다. $SiO_2$ 나노 콜로이드를 코팅하여 열처리한 표면은 무코팅 표면보다 약간 거칠게 나타났으며, 열처리 온도에 따라 표면의 산화 정도는 조도와 뚜렷한 상관관계는 가지지 않았다. 그리고 마찰계수, 마모손실 및 굽힘강도는 표면 거칠기와 관계가 없었다. SKD11 상대재에 대하여 연삭마모의 거동을 보였으며, 마찰계수와 마모손실은 비례하였다. 또한, 강도가 클수록 마찰계수가 작고, 마모손실도 작았다. $SiO_2$ 나노 콜로이드 량의 증가에 따라서 마찰계수는 증가하다가 일정하게 되었지만, 마모손실은 증가하였다. 또한 열처리 온도가 증가함에 따라서 마찰계수는 약간 증가하는 경향을 나타내었다.