• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.195-198
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• 2006

Zinc phosphate coating is required in nearly all steel cold forging operations. However, the chemical byproducts of this lubricant system are difficult to dispose of and have a negative environmental impact. In order to replace zinc phosphate based lubricants partially or completely, candidate lubricant has been developed in this study. The performance evaluation of these lubricants was conducted using the double cup extrusion test and spike forging test. With the use of the commercial FEM code DEFORM, friction factor calibration curves, i.e. cup height ratio vs. punch stroke and spike height vs. punch stroke, were established for different friction factor values. By matching the cup height ratio and the punch stroke and spike height vs. punch stroke from experiment to that obtained from FE simulations, the friction factor of the lubricants was determined. Three water-soluble lubricants; namely, Mec Homat, Royalcoat, and the developed lubricant were found to perform comparable to or better than zinc phosphate.

• Progress in Superconductivity and Cryogenics
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• v.6 no.4
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• pp.5-8
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• 2004

A low cost MOD processing using YBCO oxide powder as a starting precursor was employed for fabrication of YBCO thin films. YBCO oxide is advantageous over metal acetates or TFA salts which are popular starting precursors for conventional MOD-TFA process. YBCO thin films were prepared by oxide-precursor-based MOD process and annealing condition was optimized. The YBCO thin film annealed at 78$0^{\circ}C$ shows no transport $I_c$ and poor microstructure. However, the YBCO thin film annealed at higher temperature shows improvement in microstructure and current transport property. In order to improve critical current, YBCO thin film was prepared by double coating method. YBCO thin film prepared with double coating approach shows enhanced superconducting performance ($I_c$>100A/cm-w).

• ETRI Journal
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• v.39 no.6
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• pp.874-879
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• 2017

This paper challenges the fabrication of a thin film energy storage device on a flexible polymer substrate specifically by replacing most commonly used metal foil current collectors with coated current collectors. Mass-manufacturable spray-coating technology enables the fabrication of two different half-cell electric double layer capacitors (EDLC) with a spray-coated silver paste current collector and a Ni foil current collector. The larger specific capacitances of the half-cell EDLC with the spray-coated silver current collector are obtained as 103.86 F/g and 76.8 F/g for scan rates of 10 mV/s and 500 mV/s, respectively. Further, even though the half-cell EDLC with the spray-coated current collector is heavier than that with the Ni foil current collector, smaller Warburg impedance and contact resistance are characterized from Nyquist plots. For the applied voltages ranging from -0.5 V to 0.5 V, the spray-coated thin film energy storage device exhibits a better performance.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1353-1358
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• 2004

An experimental study of pool boiling behavior on micro-porous enhanced square heater surfaces immersed in PF5060 is performed. The effects of heater orientation, Subcooling and substrate distance on the pool boiling heat transfer performance for the double heaters were investigated under increasing heat-flux conditions. The boiling performance of micro-porous coated surface was better than that of plain surface. The double heaters with upper substrate of 0.2cm substrate interval have lower boiling performances compared with the results for the double heaters with that of 0.5cm and 1.0cm substrate interval and without the substrate. In comparison to upper heater and below heater with orientation, the upper heater has lower superheat temperature than the below heater due to the bubble sweeping.

• Journal of the Semiconductor & Display Technology
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• v.11 no.4
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• pp.1-6
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• 2012

Keeping the polarization direction of the projection light unchanged is of crucial importance for high quality of images on a double-screen 3D projection display system. It has been found that the deposition of oxide layers on the surfaces of scattering polarizer film results in an improvement of polarization maintenance property of the film. The secondary image formed on the front screen by the light scattered from the rear screen decreases by 30% through the application of oxide layers on both surfaces of the screen. Since the oxide layer can also be used as an anti-reflection (AR) coating of the film, this method is very effective for the projection display applications.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.465-465
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• 2013

Inorganic 물질인 SiO2 dielectric 위에 organic dielectric PVP (4-vinyphenol)를 spin coating으로 올려, inorganic/organic dielectric 형태의 double layer구조로 High-performance amorphous indiumgallium zinc oxide thin-film transistors (IGZO TFT)를 제작하여 보았다. SiO2 dielectric을 buffer layer로 80 nm, PVP는 10Wt% 400 nm로 구성하였으며, 200 nm single SiO2 dielectric과 동일한 수준의 leakage current 특성을 MIM Capacitor 구조를 통해서 확인할 수 있었다. 이 소자의 장점은 용액공정의 도입으로 공정 시간의 단축 및 원가 절감을 이룰 수 있으며, dielectric과 channel 사이의 균일한 interface의 형성으로 interface trap 개선 및 Yield 향상의 장점을 갖는다. 우리는 실험을 통해서 SiO2 buffer layer가 수직 electric field에 의한 leakage current을 제어하고, PVP dielectric은 interface를 개선하는 것을 확인하였다. Vth의 negative shift 및 slope의 향상으로 구동전압이 줄어들고, 균일한 I-V Curve 형성을 통해서 Process Yield의 향상을 확인하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.163-166
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• 1997

Electroluminescent(EL) dcvice based on organic thin layers have attracted lots of interests because of thier possible application as large-area light-emitting displays. It was known that MEH-PPV and 1, 1, 4, 4, -Tetraphenyl-1, 3-butadiene(TPB) has red and blue emission peak at 580nm and 480nm, respectively. In this study, MEH-PPV films and TPB films were prepared by spin coating and vacuum deposition method, respectively. Films of MEH-PPV and TPB double layer were also prepared by the same method. Photoluminescent(PL) characteristics of these single and doubler layers were investigated, where a cell structure of glass substrate/ITO/MEH-PPV and/or TPB/Al was employed. It was found that the photoluminescent efficiency of TPB film was higher than that of MEH-PPV film with a single layer and also with a double structure. These films have also different I-V characteristics.

• 연구논문집
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• s.31
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• pp.127-133
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• 2001

In chromium electrodeposition, crack is inevitably accompanied by chromium layer. Behavior of crack formation and crack density were different from the plating conditions such as current density, temperature, waveform of applied current and so on. And cracks have an influence on the corrosion resistance of chromium deposit, because corrosion occurs through the network of cracks between deposit and substrate. Therefore, many researches have been achieved in order to remove the cracks in chromium deposit. Formation of double layers, Cr/Cr and Ni/Cr were investigated to increase corrosion resistance of chromium deposit in this study. As pretreatment prior to outer chromium coating, acid pickling and current control method were examined. Cracks in cross-section of each sample were observed with SEM and CASS(Copper modified acetic acid salt spray) test was performed to evaluate corrosion resistance. It was found that corrosion resistance of Cr/Cr and Ni/Cr double layers were superior to Cr or Ni single layer from the results of CASS test.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.102-108
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• 2013

In manufacturing of solution-processed organic electronic devices, a spin coating method is frequently used, but which has a big problem. Solvent in a solution has a decisive effect such as physical and chemical damage for successive solution-based film deposition. Such a severe damage by solvent restricts for fabricating building blocks of multi-layered films from solutions. In this work, it will be shown that a proper combination of well-known solvents gives a chance to fabricate multi-layered film, also this new method was applied to make organic field effect transistor. Two types of bottom gate, bottom contact transistors were fabricated, one of which is fabricated by conventional single spin coating method, the other fabricated by double spin coating method. Compared with the electrical characteristics in a single spin coated transistor, the leakage current between source and gate electrode was decreased, ON state current was increased, and the extracted saturation mobility was multiplied more than 2.7 time for double spin coated transistors. It is suggested that the multiple coated gate dielectric structure is more desirable for high performance organic ferroelectric field effect transistors.

• Corrosion Science and Technology
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• v.8 no.2
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• pp.53-61
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• 2009

In this study, both evaluations by visual imaging for exterior view of coating and by EIS were executed for epoxy primer coated specimens deteriorated by accelerated test, and comparison and analysis were carried out for 2 evaluation methods. In the comparison between total damaged area ratio acquired by image processing method and deterioration point, higher deterioration points were appeared for rusted specimens than for non-rusted specimens. It is attributed that deterioration point per unit area ratio given for rust is higher than for peeling. In the comparison between total damaged area ratio and EIS result, impedance of coating was largely decreased as about TEX>$10^4{\Omega}{\cdot}cm^2$ or less when rust area ratio is more than about 0.1%, and blistering area ratio is more than about 3%. Charge transfer resistance ($R_{ct}$) and double layer capacitance ($C_{dl}$) values were appeared for all specimens except 2 ones, which shows that water is accumulated and steel substrate is corroded at coated film-steel interface. In the comparison between deterioration point and EIS result, more than 10 points as deterioration point were given for specimens of below $10^6{\Omega}{\cdot}cm^2$ of impedance at low frequency. For specimens deteriorated by NORSOK cyclic test, impedance was lowest of all, though deterioration point was not high. It is thought to be attributed that coating system and accelerated deterioration condition of cyclic tested specimens were different from those of main specimens. From the result, it is thought that coating resistance can be relatively more decreased than deterioration degree estimated from exterior view under more severe corrosion environment or in the present of more complex deterioration factors.