• Journal of the Korean Society for Precision Engineering
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• v.30 no.12
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• pp.1335-1340
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• 2013

Herein the water film was introduced to the hydrophilic area on the line patterned surface to solve the contradiction caused by surface roughness (high different wettability has advantage to control the droplet but high roughness for that high wettability difference causes obstruction of droplet moving). Thus the droplet on the water film could not be hindered to line direction but restricted to orthogonal direction, effectively. In addition, droplet behaviors according to droplet volume and line thickness were studied. Droplet fell off the line with narrowing the interface between the droplet and the water film on the line. When the droplet fell off the line, the plate angle was designated as a critical plate angle and it used as an indicator of surface capability to control the droplet. As a result critical plate angle increases as droplet volume decreases and line thickness increases.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1774-1777
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• 2007

Ultra-fine Ag line was automatically patterned to the extent of 10 ${\mu}m$ in width by slit coating on the $10^4$ $mm^2$ glass, which was pre-patterned as hydrophobic and hydrophilic zone by using hydrophobic material. The resistivity of Ag film was about $4{\mu}\;{\Omega}{\cdot}cm$.

• Journal of Korean Vacuum Science & Technology
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• v.5 no.1
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• pp.7-10
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• 2001

Ion induced secondary electron emission coefficients γ of protecting layers of an AC plasma display panel(AC-PDP) have been measured. In order to solve the surface charging effect during the measurement at insulating samples like MgO, a new method with the patterned gold line charge neutralization has been introduced. The measurement was performed at the samples, MgO and MgO+MgF$_2$, which showed a great difference in the firing voltage between the two protecting layers. The γ value has been compared with the firing voltage Vf of the AC-PDP with the same protecting layer. Correct relationship between γ and Vf has been observed. Thus, the patterned gold line method has been proven to be successful for the measurement of the secondary electron emission yield at insulator sample surfaces.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.471-474
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• 2004

We investigated field emission (FE) characteristics of multi-walled carbon nanotubes (CNTs) grown on all over patterned cathode electrode lines (CL pattern) and grown on along the central areas of the cathode lines(CL pattern). The CNTs grown on the SL pattern showed a lower threshold voltage and higher emission current than those on the CL pattern, due to the concentration of electric fields at the edges of the cathode lines. For the SL-patterned CNTs, however, the FE gradually spread out to the neighbors with time, and was instantly extinguished in some area and then slowly resumed again. Such areal- spread FE did not occur for the CL-patterned sample, leading to the stable FE together with the instant turn-on capability. It is suggested that the spread FE and instability for the SL-patterned CNTs may be related to the electrical charging on the insulator surface around the cathode line edges.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.29 no.2
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• pp.111-118
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• 2023

In this study, the feasibility of laser patterning on the surface of food packaging polymer film was confirmed, and the surface patterning process conditions of femtosecond laser were established. In addition, it was proved that the surface properties of the film can be changed and controlled through the fabrication of various patterned films on the surface of food packaging films such as HDPE, PP, and PET. Various patterned surfaces, including large-scale circular patterns induced by a single femtosecond laser pulse, roughness patterns achieved by overlapping single pulses by 30%, straight line patterns, roughness patterns obtained by overlapping straight line patterns, and grid patterns formed by intersecting straight line patterns were fabricated. The characteristics of the patterned HDPE, PP, and PET films, based on the surface pattern structure and size, were analyzed using SEM, AFM, and contact angle measurements. Compared to the surface of each control film without femtosecond laser patterning, the contact angles of the surfaces of large-area circular patterning HDPE and PP films, large-area roughness patterning HDPE and PP films by overlapping 30% of single pulses, and large-area roughness patterning PET film by overlapping rectilinear patterning were in the range of 27.1-37.5 degree. This indicated that the HDPE, PP, and PET films became more hydrophilic after patterning. On the other hand, the HDPE film patterned with a large-scale grid pattern exhibited a contact angle of 120.4 degree, indicating that the HDPE film became more hydrophobic after patterning. Therefore, films that have been changed to hydrophilic surfaces through patterning can be used in anti-fouling applications where proteins, cells, viruses, and other food materials do not adhere or are easily detached. In addition, if a superhydrophobic surface of 150 degrees or more is fabricated through more precise lattice patterning in the future, it will be possible to use it for superhydrophobic surface applications such as self-cleaning.

• Journal of the Korean Society for Heat Treatment
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• v.33 no.1
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• pp.25-32
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• 2020

In this study, the tribology of laser patterned DLC thin film was studied. DLC thin films were coated by RF-PECVD to improve the durability of tungsten carbide (WC) materials. DLC thin films have high hardness and low friction characteristics. Dot and line patterning was processed on the surface of DLC thin film with femtosecond laser, and the coefficient of friction was improved. As a result of ball on disk abrasion test, the hardness and friction coefficient of DLC thin films were much better than that of WC material. The friction coefficient of DLC thin film with dot patterning and line patterning showed better results. The excellent performance of the laser patterned DLC coating is appeared to reduce the coefficient of friction due to the reduction of surface contact area.

• Laser Solutions
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• v.15 no.3
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• pp.1-6
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• 2012

The friction force of patterned needle in elastomer have been investigated to verify the application for bio and plastic industry. The micro pattern on the needle surface were prepared by 266 nm, 20 ns laser and 800 nm, 220 fs laser, which were able to generate the different surface roughness. The friction force was measured by the load cell of 10 N capacity. As the results, the friction force of no patterned needle is almost constant during the needle penetrates the silicone rubber sample. However, the needle having asperities shows the variation of the friction force. The higher the surface roughness is, the smaller the friction force is until the surface roughness is very high. In our experiment conditions, the reduction of the friction force by 20 % compared to no pattern needle was achieved with straight and $50{\mu}m$ discrete line generated by 266 nm, 20 ns laser.

• Journal of Welding and Joining
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• v.34 no.4
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• pp.23-27
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• 2016

A 3D printed metal part and thermal plastic polymer part were joined by direct laser irradiation. The 3D metal part was fabricated by using DED(Direct Energy Deposition) with STS316 material. The experiment was carried out through no patterned metal surface, 3D metal printed surface and micro laser patterned surface. The most secure joining quality was obtained at the laser micro patterned surface specimen and the counterparts of polymers were PLA and PE based thermo plastics. The applied laser power was 350Watt and the distance of patterns was maintained at $150{\mu}m$. The laser line width was optimized at $450{\mu}m$ and the laser micro pattern depth was $180{\mu}m$ for the best joining quality. Based on the result analysis, the possibility of laser material joining for metal to polymer was proposed and multi-material joining will be possible in 3D laser direct material fabrication.

• Journal of the Korean institute of surface engineering
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• v.52 no.6
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• pp.357-363
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• 2019

We investigated a synthesis yield and diameter distribution of single-walled carbon nanotubes (SWNTs) with respect to the growth position in a horizontal chemical vapor deposition (CVD) chamber. Thin films and line-patterned Fe films (0.1 nm thickness) were prepared onto ST-cut quartz substrates as catalyst to compare the growth behavior. The line-patterned samples showed higher growth density and parallel alignment than those of the thin film catalyst samples. In addition, line density of the aligned SWNTs at central region of the chamber was 7.7 tubes/㎛ and increased to 13.9 tubes/㎛ at rear region of the CVD chamber. We expect that the enhanced amount of thermally decomposed feedstock gas may contribute to the growth yield enhancement at the rear region. In addition, the lamina flow in the chamber also contribute to the perfect alignment of the SWNTs based on the value of gas velocity, Reynold number, and Knudsen coefficient we employed.

• Journal of the Semiconductor & Display Technology
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• v.2 no.2
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• pp.1-4
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• 2003

We have developed a rotating compensator spectroscopic ellipsometer (RCSE). As the ellipsometry measures a change in the polarization state of a light wave upon non-normal reflection from surface, the degree of sensitivity is enhanced greatly through the detection of relative phase change. RCSE acquires additional information from the non-ideal surface of sample and operates over the photon energy range from 1.5 to 4.5 eV. We applied RCSE to measure the optical properties of films and the line-width of patterned PR films on crystalline silicon.