• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2015-2020
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• 2007

Diesel is an excellent candidate fuel for fuel cell applications due to its high hydrogen density and well-established infrastructure. But, it is hard to guarantee desirable performance of diesel reformer because diesel reforming has several problems such as sulfur poisoning of catalyst and carbon deposition. We have been focusing on diesel autothermal reforming(ATR) for substantial period. It is reported that ATR of diesel has several technical advantages such as relatively high efficiency and fuel conversion compared to steam reforming(SR) and partial oxidation(POX). In this paper, we investigate characteristics of diesel reforming under various ratios of reactants(oxygen to carbon ratio, steam to carbon ratio) for improvement of reforming performances(high reforming efficiency, high fuel conversion, low carbon deposition). We also exhibit calculated heat balance of autothermal reformer at each condition to help thermal management of SOFC system.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.657-659
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• 2004

Trivalent cerium ($Ce^{3+}$) activated yttrium aluminum garnet ($Y_3Al_5O_{12}$, YAG) phosphor thin films were deposited on quartz glass substrates by rf magnetron sputtering. The effects of sputtering parameters and annealing condition on the luminescent properties were investigated. The sputtering parameters were $O_2$/Ar gas ratio, rf power, and deposition time. The films were annealed at 1200 $^{\circ}C$ for 5 hours in $N_2+$vacuum atmosphere. Polycrystalline YAG:Ce thin film phosphor could be obtained with a gas ratio of $O_2$/(Ar+$O_2$)=0.5 after post-annealing. PL spectra excited at 450 nm showed a yellow single band at 550 nm.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.25.2-25.2
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• 2009

Vertically aligned zinc oxide(ZnO) nanorods (NRs) with different surface morphology were grown by metal organic chemical vapor deposition (MOCVD) on sapphire substrate with different deposition condition. Based on the surface morphology, ZnO nanostructures are divided into three types: nanoneedles, nanonails and nanorods with rounded tip. Variable temperature photoluminescence (PL) have employed to probe the exciton recombination in high density and vertically aligned ZnO Nanorod arrays. Low temperature photoluminescence measurements do not show any significant yellow emission, but the near band edge excitonic emission shows very strong dependence with the surface morphology. The recombination properties are expected to be different due to different surface-to-volume ratio and distribution of potential fluctuations of intrinsic defects.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.1
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• pp.128-133
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• 2010

The Titanium has many superior characteristics which are specific strength, heat resistance, corrosion resistance, organism compatibility, non-magnetic and etc. and their quantity are abundant. this study performed turning operation of Ti-6Al-4V alloy using the TiAlN Coated Tool which treated Physical Vapor Deposition. Experimental works are also executed to measure cutting force, tool wear, chip figuration and surface roughness for different cutting conditions. As a result of study. Cutting depth influences on the cutting force much more than the feed rate and the value of the cutting force is the most stable at the depth of 1.0mm. And tool wear was serious at over 100m/min of cutting speed and cutting condition was excellent at 1.0mm of cutting depth.

• Journal of Welding and Joining
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• v.14 no.5
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• pp.87-94
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• 1996

It has been well known in GMA welding process that wire feeding speed (WFS) or deposition rate increases linealy with the increase of wire extension. In this investigation, however, such an well-known relationship was .reconsidered in terms of contact-tube to work distance (CTWD) instead of wire extension. To verify the proposed relationship between WFS and CTWD, bead-on-plate welding was performed with various CTWDs in the range of 15∼35mm under the condition of near-constant voltage and current As expected, the test results showed an excellent linear relation between WFS and CTWD. Furthermore, the value of the slope turned out to be quite similar to those of previous investigators obtained either theoretically or experimentally through the Precise measurement of electrode extension. Present result also demonstred that the increase of CTWD could be very practical measure for increaring deposition rate without any increase of heat input Depending on the tip recess the practical maximum of CTWD was appeared to be limited somewhere in 25∼30mm mainly due to the entrappment of porocity.

• Journal of Sensor Science and Technology
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• v.13 no.4
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• pp.264-269
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• 2004

This paper describes on an advanced technology of 3C-SiC/Si(100) wafer direct bonding using PECVD oxide to intermediate layer for SiCOI(SiC-on-Insulator) structure because it has an attractive characteristics such as a lower thermal stress, deposition temperature, more quick deposition rate and higher bonding strength than common used poly-Si and thermal oxide. The PECVD oxide was characterized by ATR-FTIR. The bonding strength with variation of HF pre treatment condition was measured by tensile strength measurement system. After etch-back using TMAH solution, roughness of 3CSiC surface crystallinity and bonded interface was measured and analyzed by AFM, XRD, and SEM respectively.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1551-1554
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• 2005

The Titanium has many superior characteristics Which are specific strength, heat resistance, corrosion resistance, organism compatibility, non-magnetic and etc. and their quantity are abundant. this study performed turning operation of Ti-6Al-4V alloy using the TiAlN Coate Tool which treated PVD (Physical Vapor Deposition). Experimental works are also executed to measure cutting force, chip figuration and surface roughness for different cutting conditions. As a result of study. Tool wear was serious at over 100m/min of cutting speed and cutting condition was excellent at 1.0mm of cutting depth.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04a
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• pp.57-58
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• 2008

Microcrystalline (${\mu}c$) silicon thin films were prepared on glass by plasma-enhanced-chemical-vapor-deposition (PECVD) at various substrate temperature, and dilution ratio of $H_2$ with $SiH_4$. The structural and optical properties of. the ${\mu}c-Si$ thin films were investigated using XRD and UV-VIS spectrophotometer. The ${\mu}c-Si$ thin film with 42 nm grain size was grown at optimal condition of 2.5 Torr, spacing between electrodes of 3cm, deposition time of 3000s, RF power of 200W, substrate temperature of $350^{\circ}C$, $SiH_4$ ($20%SiH_4$+80%He) of 50sccm, and $H_2$ of 100sccm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.359-362
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• 2003

Electrophoretic deposition (EPD) of alcohol YBCO suspensions on the Ag wire electrode is studied. Poly(ethylene glycol) was coordinated to a structure formed by the EPD process with YBCO particles. The suspension is characterized in terms of zeta potential and conductivity. The d.c electric fields of 200-300 V/cm are applied for 1-10 min. The optimal condition for the EPD allows modifying the properties and microstructure of the deposited films. Superconducting coatings with nanometer-sized pores and a preferred orientation along the c-axis were prepared from the result with chemically modified precursor solution. In contrast, YBCO coatings of submicrometer-sized pores and randomly orientated grains were prepared from the solution without PEG.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1256_1257
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• 2009

We have grown, for the first time to our knowledge, N-doped ZnO thin films on sapphire substrate by employing novel dielectric barrier discharge in pulsed laser deposition (DBD-PLD). DBD guarantees an effective way for massive in-situ generation of N-plasma under the conventional PLD process condition. Low-temperature photoluminescence spectra of the N-doped ZnO film provided near band-edge emission after thermal annealing process. The emission peak was resolved by Gaussian fitting to find a dominant acceptor-bound exciton peak ($A^0X$) that indicates the successful p-type doping of ZnO with N.