• Journal of the Korean institute of surface engineering
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• v.50 no.1
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• pp.17-23
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• 2017

This work demonstrates arc generation and anodic film formation behaviors on Al1050 alloy during PEO (plasma electrolytic oxidation) treatment under a constant direct current in an alkaline electrolyte containing silicate, carbonate and borate ions. Only one big arc more than 2 mm diameter was generated first at the edges and it was moving on the fresh surface or staying occasionally at the edges, resulting in the local burning due to generation of an extremely big orange colored arc at the edges. Central region of the flat surface was not fully covered with PEO films even after sufficiently long treatment time because of the local burning problem. The anodic oxides formed on the flat surface by arcing once were found to consist of a number of small oxide nodules with spherical shape of $3{\sim}6{\mu}m$ size and irregular shapes of about $5{\sim}10{\mu}m$ width and $10{\sim}20{\mu}m$ length. The anodic oxide nodules showed uniform thickness of about $3{\mu}m$ and rounded edges. These experimental results suggest that one big arc observed on the specimen surface under the application of a constant direct current is composed of a number of small micro-arcs less than $20{\mu}m$ size.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.4
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• pp.324-329
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• 2000

We investigated the effect of hydrogen ion beam on the formation of DLC thin film, which is deposited on the Si substrate with negative carbon ion by $Cs^+$ ion sputtering and positive hydrogen ion by Kauffmann type ion source. The amount of hydrogen in the DLC films increased as increasing hydrogen gas flow rate from 0 sccm to 12 sccm. As increasing hydrogen flow rate, $sp^2$bonding structure increased. The reason is that the hydrogen ions have relatively high energy, although total amount of hydrogen is very small compared with that of CVD process. These results suggest that the physical energy transfer plays a dominant role on the formation of DLC film.

• Journal of the Korean Graphic Arts Communication Society
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• v.14 no.1
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• pp.1-15
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• 1996

In this paper, the preparation of lead zirconium titanate(PZT) thin film by sol-gel processing was descried. Thin film coated with thickness of 4${\mu}{\textrm}{m}$ on the stainless steel substrates using the multiple spin-coating process. The crystalline phases of PZT powder and film were investigated by X-ray diffraction pattern and PZT thin film has perovskite structure over 600 C annealing temperature. Corona charging characteristics of the ferroelectric PZT thin film at 600 C were investigated by electrophotographic measurement. A difference in the charging characteristics between positive and negative corona charging was found. The charge acceptance depended in the polarity of corona and the poling of film. According to the D-E hysteresis measurment, PZT thin film can be poled by corona charging without use of top electrode. The remnant polarization in the PZT thin film is generally in the order of 48$\mu$C/$\textrm{cm}^2$. From this results, the ferroelectric PZT thin film will be possible to apply for the add-on type imaging formation.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.5
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• pp.45-51
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• 1997

Low temperature activation of dopants which were doped using ion mass doping system in amorphous silicon(a-Si) thin films was investigated. With a 20.angs.-thick Ni film on top of the a-Si thin film, the activation temperature of dopants lowered to 500.deg. C. When the doping was performaed after the deposition of Ni thin film on the a-Si thin films (post-doping), the activation time was shorter than that of dopants mass, the activation time of the dopants doped by pre-doping method increased. It turned NiSi2 formation, while the decrease of activation time was mainly due to the enhancement of the NiSi2 formation by mixing of Ni and a-Si at the interface of Ni and a -Si thin during the ion doping process.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.2
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• pp.87-96
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• 1995

The cutting force is the most important variable to understand the mechanics of ultra-precision machining. Most dynamometers, however, monitor the static cutting force only. But it is necessary to measure the dynamic cutting force to clarify the machinability of the material, the formation of the chip, chatter and the wear of the tool. In this research, measurement of the dynamic cutting force in order to clarify the machin-ability of the material, the formation of the chip, chatter and the wear of the tool has been conducted. A combined-type dynamometer which could measure the static cutting force and the dynamic cutting force by use of strain gauges and a piezo-film accelerometer has been developed. An analysis of the dynamometer also has been carried out.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2003.11a
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• pp.169-173
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• 2003

We demonstrated the applicability of dry film photoresist (DFR) in photolithography process for fine pitch solder bumping on the polytetrafluoroethylene (PTFE/Teflon) printed circuit board (PCB). The copper lines were formed with $100\;{\mu}m$ width and $18\;{\mu}m$ thickness on the PTFE test board, and varying the gaps between two copper lines in a range of $100-200\;{\mu}m$. The DFRs of $15\;{\mu}m$ thickness were laminated by hot roll laminator, by varying laminating temperature from $100^{\circ}C\;to\;150^{\circ}C$ and laminating speed. We found the optimum process of DFR lamination on PTFE PCB and accomplished the formation of indium solder bumps. The optimum lamination condition was temperature of $150^{\circ}C$ and speed of about 0.63 cm/s. And the smallest size of indium solder bump was diameter of $50\;{\mu}m$ with pitch of $100\;{\mu}m$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.5
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• pp.347-350
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• 2013

By inserting a very thin metal layer of Ag between two outer oxide layers of amorphous silicon indium zinc oxide (SIZO), we fabricated a highly transparent SIZO/Ag/SIZO multilayer on a glass substrate. In order to find the optimized thickness of Ag layers, we investigated the variation of optical properties depending on Ag thickness. It was found that the transition of Ag layer from island formation to a continuous film occurred at a critical thickness. Continuity of the Ag film is very important for optical properties in SIZO/Ag/SIZO multilayer. With about 15 nm thick Ag layer, the multilayer showed a high optical transmittance of 80% at 550 nm and low emissivity in IR.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.197-203
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• 1999

Stainless steels in general has passive film having strong corrosion resistance on surface. Therefore it must be necessarily removed by etching in mixing solution of sulfuric and chloric acid before Nitriding treatment. But in the ion nitriding, nitride layer was easily formed because passive film was removed without difficult by sputtering effect. The removal extent of these passive films was greatly effected by gas mixing ratios and pressure and holding times of pre sputtering factors in pre sputtering stage. As a results of experiment it has been known that pre sputtering pressure and holding time was not nearly effective on the formation behavior of nitride layer. But when A/H2 gas mixing ratios was 1/2 (vol%) was the most effective of the all pre sputtering conditions. It was resulted from the combination of mechanical reaction byArgon bombardment and chemical reaction by reduction of hydrogen on the passive film.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05b
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• pp.94-97
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• 2005

Bismuth high Tc superconducting thin films are fabricated via a co-deposition process by an ion beam sputtering with an ultra low growth rate, and sticking processing of the respective elements are evaluated. The sticking processing of bismuth element in bismuth high Tc superconducting thin film formation was observed to show a unique temperature dependence; it was almost a constant value of 0.49 below about $730^{\circ}C$ and decreased linearly over about $730^{\circ}C$. This temperature dependence can be elucidated from the evaporation and sublimation rates of bismuth oxide, $Bi_2O_3$, from the film surface. It is considered that the liquid phase of the bismuth oxide plays an important role in the bismuth phase formation in the co-deposition process.

• Journal of Magnetics
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• v.16 no.4
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• pp.403-407
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• 2011

Metal-insulator type, nano-granular soft magnetic films have been reviewed from the viewpoint of high frequency magnetic materials. The formation of nano-granular structure is related to the magnitude of heat of formation of intergranule materials. Variation of the ratio of granule phase to intergranule phase in the film is found to produce various characteristics in the magnetic properties of the film. The HRTEM observation reveals that neighboring granules in the film with above 60 at.% Co, contact at considerable points and the films show soft magnetic properties which are explainable in terms of the random anisotropy model for nano-crystalline materials. Addition of Ni group elements in Co-O based films enhances their anisotropy field up to 400 Oe and they exhibit excellent frequency response of permeability. Also, large electromagnetic noise suppression effect is demonstrated as one of their potential applications.