• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.227-228
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• 2012

In interfaces between carbon black or Pt and FTO glass in dye-sensitized solar cell counter electrodes, a marginal resistant channel for electrons, we tried to improve the connection by modifying the sintering process. A stepwise sintering process for carbon black and Pt counter electrodes was applied and its effect on power conversion efficiency was studied. Power conversion efficiencies of built-in DSSC made by a one-step sintering process with carbon black and Pt counter electrodes were about 5.01% and 5.02%, respectively. Cells made with the stepwise sintering process were 5.96% and 6.21%, respectively, indicating an 20% improvement. Fill factor (FF) increased, and it was them main reason for the power conversion efficiency improvement. Step wise sintering increased the adhesion of the interface and reduced the film thickness and surface roughness. As a result, the resistivity of the counter electrode and EIS impedance of DSSCs decreased.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.306-309
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• 2000

In this work, we investigated A1 cluster deposition on Al (100) surface using molecular dynamics simulation. A result of simulations showed that large cluster with low energy was proper for good surfaced-films without craters at the low temperatures. We investigated the maximum substrate temperature and the time taken for substrate temperature to reach its maximum as a function of cluster size in the case of the same total energy and in the case of the same energy Per atom. The correlated collisions play an important role in interaction between energetic cluster and surface, and as cluster size and cluster energy increases, the correlated collisions effect affects interaction between energetic cluster and surface.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.3
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• pp.55-60
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• 2008

Until a recent date, the surface finish generated in turning by the conventional cutting tool is directly related to the feed rate and the size of the tool nose radius. With this tool a large feed rate will give poorer surface finish and a large nose radius will generate a better surface finish. Recently a new concept in the tool design is introduced to achieve a better surface finish at a higher feed rate. This is the wiper tool, which has the portion of nose with infinite radius. This can remove the ridges left when the conventional tool is used. In this study two series of cutting tests with the wiper tool and the conventional tool are carried out under the various cutting conditions of cutting depth, feed rate and cutting speed. The effects of the wiper design and the cutting conditions on the surface roughness resulted are carefully examined and compared.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.5
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• pp.76-85
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• 2013

This study was carried out to investigate the relation between surface roughness and heat absorption capability of materials for solar collector. For this purpose, 3 kinds of materials (copper, aluminum, iron), 5 kinds of surface roughness (scrubber, alumina sand #80, #200, #400, glass bead) and 2 kinds of surface treatment (black chrome plating, copper black coating) were used for finding optimal conditions to apply solar collector. As the results, it was confirmed that the optimal relations between surface roughness and surface treatment as well as optimal materials were necessary. Further, heat absorption capability was showed good results in cases of copper materials, glass bead and black chrome plating.

• Bulletin of the Korean Chemical Society
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• v.30 no.8
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• pp.1805-1810
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• 2009

The adsorptions of trimethygallium (TMG) and arsine (As$H_3$) on H/Si(100)-2x1 surface were theoretically investigated. In the case of TMG adsorption, methane loss reaction, surface methylation, hydrogen loss reaction and ring closing reaction channels were found. The mechanism of As$H_3$ adsorption on the surface was also identified. Among these, the methane loss reaction depositing –Ga(C$H_3)_2$ was found to be the major channel due to its low barrier height and the large exothermicity. The surface methylation reaction is the second most favorable channel. In contrast, arsine turned out to be less reactive on the surface, implying that Arsine surface reaction would be the rate limiting step in the overall ALD process.

• Restorative Dentistry and Endodontics
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• v.17 no.1
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• pp.166-180
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• 1992

One disadvantage of Glass Ionomer Cement Restoration is the difficulty in polishing. To find the appropriate polishing method, we polished the surface of Glass Ionomer Cement Restorations by 11 combination methods serially using disks shared with large-small particles and evaluated the polishing process in terms of surface roughness, surface roughness curve, and SEM findings. In addition, a visible light curing type bonding material was applied to evaluate the possible improvement in surface properties. The following results were obtained. 1. The disk surface of Glass Ionomer Cement was polished serially by disks with superfine particles, but it didn't become smooth. 2. The surface of Microfilled Composite resin became smoother as using a disk with finer particles. 3. When a visible light curing type bonding material was applied in finishing process, the surface of Glass Ionomer Cement became smooth as much as the applied matrix.

• Journal of the Korean institute of surface engineering
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• v.39 no.4
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• pp.166-172
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• 2006

Metallized Polyimide films are extensively used as base materials in microelectronics, optical and automotive applications. However it is difficult to deposit metals on those because of their structural stabilities. In this work, polyimide films are modified by a wet process with alkalinemetalhydroxide and additives to introduce functional groups. The surface molecular structures of polyimide are investigated using X-ray photoelectron spectroscopy(XPS), fourier transform infrared reflection spectroscopy(FTIR-ATR), atomic force micro-scopic(AFM). XPS spectra and FTIR spectra show that the surface structure of polyimide is converted into potassium polyamate. AFM image and AFM cross-sectional analyses reveal the increased roughness on the modified surface of polyimide films. As a result, it is shown that the adhesion strength between polyimide surface and electroless nickel layer is increased by the nano-anchoring effect.

• Journal of the Korean institute of surface engineering
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• v.32 no.3
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• pp.253-256
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• 1999

Wet plating has been initiated and developed as a major surface finishing technology as of the long customized and highly productive process until now. As the external compression by virtue of the environmental preservation becomes stricter, there has been new move to adapt dry plating line instead of conventional wet plating one in domestic surface finishing industry. Dry plating, so-called, plasma surface technology has been developed in semiconducting industry and becomes a key technology to be useful as an alternative to wet plating in surface finishing industry. The historical progress of domestic surface finishing industry was outlined with the background on the adaptation of three dry plating processes-plasma spraying, plasma nitriding and ion plating. The present status of domestic industrial activity was covered on major alternative to wet plating.

• Korean Journal of Materials Research
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• v.23 no.9
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• pp.501-509
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• 2013

To evaluate the development of the microstructure and mechanical properties on surface modified and post-heattreated Inconel 718 alloy, this study was carried out. A friction stir process as a surface modification method was employed, and overlap welded Inconel 718 alloy as an experimental material was selected. The friction stir process was carried out at a tool rotation speed of 200 rpm and tool down force of 19.6-39.2 kN; post-heat-treatment with two steps was carried out at $720^{\circ}C$ for 8 h and $620^{\circ}C$ for 6 h in vacuum. To prevent the surface oxidation of the specimen, the method of using argon gas as shielding was utilized during the friction stir process. As a result, applying the friction stir process was effective to develop the grain refinement accompanied by dynamic recrystallization, which resulted in enhanced mechanical properties as compared to the overlap welded material. Furthermore, the post-heat-treatment after the friction stir process accelerated the formation of precipitates, such as gamma prime (${\gamma}^{\prime}$) and MC carbides, which led to the significant improvement of mechanical properties. Consequently, the microhardness, yield, and tensile strengths of the post-heat-treated material were increased more than 110%, 124% and 85 %, respectively, relative to the overlap welded material. This study systematically examined the relationship between precipitates and mechanical properties.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1220-1224
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• 2007

The effects of plasma damages to the organic thin film transistor (OTFT) during the fabrication process are investigated; metal deposition process on the organic gate insulator by plasma sputtering mainly generates the process induced damages of bottom contact structured OTFTs. For this study, various deposition methods (thermal evaporation, plasma sputtering, and neutral beam based sputtering) and metals (gold and Indium-Tin Oxide) have been tested for their damage effects onto the Poly 4-vinylphenol(PVP) layer surface as an organic gate insulator. The surface damages are estimated by measuring surface energies and grain shapes of organic semiconductor on the gate insulator. Unlike thermal evaporation and neutral beam based sputtering, conventional plasma sputtering process induces serious damages onto the organic surface as increasing surface energy, decreasing grain sizes, and degrading TFT performance.