• Laser Solutions
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• v.7 no.1
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• pp.29-36
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• 2004

The dynamics of laser-induced plasma/shock wave and the interaction with a surface in the laser shock cleaning process are analyzed by optical diagnostics. Shock wave is generated by a Q-switched Nd:YAG laser in air or with N$_2$, Ar, and He injection into the focal spot. The shock speed is measured by monitoring the photoacoustic probe-beam deflection signal under different conditions. In addition, nanosecond time-resolved images of shock wave propagation and interaction with the substrate are obtained by the laser-flash shadowgraphy. The results reveal the effect of various operation parameters of the laser shock cleaning process on shock wave intensity, energy-conversion efficiency, and flow characteristics. Discussions are made on the cleaning mechanisms based on the experimental observations.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.4
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• pp.770-783
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• 2015

Lately, high production rate welding processes for Al alloys, which are used as LNG FPSO cargo containment system material, have been developed to overcome the limit of installation and high rework rates. In particular, plasma-metal inert gas (MIG) hybrid (PMH) welding can be used to obtain a higher deposition rate and lower porosity, while facilitating a cleaning effect by preheating and post heating the wire and the base metal. However, an asymmetric undercut and a black-colored deposit are created on the surface of PMH weld in Al alloys. For controlling the surface defect formation, the wire feeding speed and nozzle diameter in the PMH weld was investigated through arc phenomena with high-speed imaging and metallurgical analysis.

• Membrane and Water Treatment
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• v.1 no.1
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• pp.83-92
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• 2010

To improve the antifouling characteristics of polypropylene hollow fiber microporous membranes in a submerged membrane-bioreactor for wastewater treatment, the surface-modification was conducted by Ar plasma treatment. Surface hydrophilicity was assessed by water contact angle measurements. The advancing and receding water contact angles reduced after the surface modification, and hysteresis between the advancing and receding water contact angles was enlarged after Ar plasma treatment due to the increased surface roughness after surface plasma treatment. After continuous operation in a submerged membrane-bioreactor for about 55 h, the flux recovery after water cleaning and the flux ratio after fouling were improved by 20.0 and 143.0%, while the reduction of flux was reduced by 28.6% for the surface modified membrane after 1 min Ar plasma treatment, compared to those of the unmodified membrane. Morphological observations showed that the mean membrane pore size after Ar plasma treatment reduced as a result of the deposition of the etched species; after it was used in the submerged membrane-bioreactor, the further decline of the mean membrane pore size was caused by the deposition of foulants. X-ray photoelectron spectroscopy and infrared spectroscopy confirmed that proteins and polysaccharide-like substances were the main foulants in the precipitate.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1682-1684
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• 2004

In this study, the surface properties of PET film were analyzed after plasma surface treatment. After plasma treatment of surface roughness and XPS were evaluated to analyze the chemical property, while the surface potential decay and surface resistivity was measured to analyze the electrical characteristic. When plasma discharge treatment was conducted for less than 10 minutes, the electrical insulating property was found to be improved through evaporation of low molecular weight materials and cleaning of surface. However, when the treatment was conducted for more than 10 minutes, the insulating property was decreased due to excessive discharge energy. Analysis of chemical characteristics showed that 10-minute treatment resulted in increase of C-O and O=C-O. However, when treated for more than 10 minutes, they were relatively decreased.

• Journal of the Korean institute of surface engineering
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• v.48 no.5
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• pp.245-252
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• 2015

In recent years, the cleaning and activation technology of surfaces using atmospheric plasma as well as the deposition technology for coating using atmospheric plasma have been demonstrated conclusively and drawn increasing industrial attention. Especially, due to the simplicity, the technology using atmospheric plasma enhanced chemical vapor deposition has been widely studied from many researchers. The plasma source type commonly used as the stabilization of diffuse glow discharges for atmospheric pressure plasma enhanced chemical vapor deposition pressure is the dielectric barrier discharge. In this review paper, some kinds of modified dielectric barrier discharge type will be presented. And, the characteristics of silicon based compound such as SiOx and SiNx deposited using atmospheric plasma enhanced chemical vapor system will be discussed.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.421-424
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• 2003

An AP plasma technology has been developed for the application of dry cleaner, PR ashing and PI rework in the large glass size. The technology is cost effective, environment friendly, and best fits for coming generation LCD production since the design is easily scalable to bigger size glasses. Surface cleaning results based on the contact angle study has been presented for $5^{th}$ generation LCD bare glass. PR ashing results and various parametric studies have been also presented.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.629-629
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• 2013

Graphene is a carbon based material and it has intriguing features, such as phenomenally strong, thin, flexible, transparent and conductive, those make it attractive for a broad range of applications.Unfortunately, graphene is extremely sensitive to contamination. When we fabricate graphene devices, electrical properties of graphene are altered [1], and the charge carrier mobility drops accordingly by orders of magnitude. This significant impact on electron mobility occurs because any surrounding medium could act as a dominant source of extrinsic scattering, which effectively reduces the mean free path of carriers [2,3]. The dominant contaminant is generated through fabrication stage by polymethyl methacrylate (PMMA) [4], or photo resist (PR). Surface contamination by these residues has long been a critical problem in probing graphene's intrinsic properties. If we clearly solve this problem, we can get highly performed graphene devices. Here, we will report on graphene cleaning process by Induced Coupled Plasma (ICP). We demonstrated how much decomposition of residue impact on improving electrical properties of graphene.

• Journal of Powder Materials
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• v.8 no.1
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• pp.61-69
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• 2001

Spark-Plasma Sintering(SPS) is one of the new sintering methods which takes advantages both inconventional pressure sintering and electric current sintering. It is known that SPS is very effective for the densification of hard-to-sinter materials like refractory metals, intermetallic compounds, glass and ceramics without grain growth. However, a clear explanation for sintering mechanism and an experimental evidence for the formation of weak plasma during SPS are not given yet. In this study, fundamental study on sintering behavior and mechanism of SPS was investiged. For this study, various spherical Fe powders were prepared such as as-received, as-reduced, and as-oxidized and then sintered by SPS facility. In order to confirm the surface cleaning effect during SPS neck region and fracture surface of sintered body was observed and analyzed by SEM/EPMA. Densification behavior was analyzed from the data of deflection along the pressure axis. Some specimens were additionally produced by Hot Pressing and the results were compared with those of SPS.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.4711-4717
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• 2011

Formation of TiN films by PVD method and the DC and RF sputtering deposition method can be applied, the injected gas to generate plasma ionization rate of the film forming speed is slow away, anything to increase the adhesion between films limitations have. To improve this, to investigate the deposition and ion beam evaporation simultaneously IBAD(Ion beam assisted deposition) when used, Ion beam surface coating material prior to the survey because the surface cleaning effect of a large, high film adhesion can be obtained. In addition, the high vacuum and low temperature, high purity thin film of uniform thickness in the benefits is.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.3
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• pp.53-59
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• 2009

Low pressure mercury lamp type UV equipments have been widely used for cleaning and modification of PCB surfaces. To enhance the productivity of the process, we newly developed remote DBD type atmospheric pressure plasma equipment. The productivity of both equipments could be compared by measuring surface contact angle for various transferring speed. By the result of the measurement, we could verify that the productivity of the atmospheric pressure plasma be superior to the productivity of the UV equipment. XPS experiments confirmed that the surface effect of the UV and atmospheric pressure plasma processing are similar for each other. Organic contamination level was reduced after the processing and some surface elements were oxidized for both cases. Finally, the atmospheric pressure plasma equipment was adapted to flip chip BGA's flux printing process and it was concluded that the printing uniformity be enhanced by the atmospheric pressure plasma surface treatment.