• Corrosion Science and Technology
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• 제7권1호
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• pp.1-5
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• 2008

The gas atmosphere in continuous annealing and galvanizing lines alters both composition and microstructure of the surface and sub-surface of sheet steel. The formation and morphology of the oxides of alloying elements in High Strength Interstitial Free (HS-IF), Dual Phase (DP) and Transformation-Induced Plasticity (TRIP) steels are strongly influenced by the furnace dew point, and the presence of specific oxide may result in surface defects and bare areas on galvanized sheet products. The present contribution reviews the progress made recently in understanding the selective formation of surface and subsurface oxides during annealing in hot dip galvanizing and conventional continuous annealing lines. It is believed that the surface and sub-surface composition and microstructure have a pronounced influence on galvanized sheet product surface quality. In the present study, it is shown that the understanding of the relevant phenomena requires a combination of precise laboratory-scale simulations of the relevant technological processes and the use of advanced surface analytical tools.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.462-462
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• 2013

Gallium Oxide (Ga2O3) has been widely investigated for the optoelectronic applications due to its wide bandgap and the optical transparency. Recently, with the development of fabrication techniques in nanometer scale semiconductor materials, there have been an increasing number of extensive reports on the synthesis and characterization of Ga2O3 nano-structures such as nano-wires, nanobelts, and nano-dots. In contrast to typical vaporliquid-solid growth mode with metal catalysts to synthesis 1-dimensional nano-wires, there are several difficulties in fabricating the nanostructures by using sputtering techniques. This is attributed to the fact that relatively low growth temperatures and higher growth rate compared with chemical vapor deposition method. In this study, Ga2O3 chestnut burr were synthesized by using radio-frequency magnetron sputtering method. In contrast to typical sputtering method with sintered ceramic target, a Ga2O3 powder (99.99% purity) was used as a sputtering target. Several samples were prepared with varying the growth parameters, especially he growth time and the growth temperature to investigate the growth mechanism. Samples were characterized by using XRD, SEM, and PL measurements. In this presentation, the details of fabrication process and physical properties of Ga2O3 nano chestnut burr will be reported.

• Journal of Korean Society for Atmospheric Environment
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• 제20권E2호
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• pp.69-75
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• 2004

In this study, thin film gas sensor based on tin oxide was fabricated to examine its characteristics. Target gas is acetonitrile ($CH_3$CN) which is a blood simulant for the chemical warfare agent. Sensing materials are SnO$_2$ SnO$_2$/Pt, and Sn/Pt with thickness from 1000 to 3000 $\AA$. The sensor consists of a sensing electrode with inter-digit (IDT) type in front side and a heater in rear side. Resistance changes of sensing materials are monitored on real time basis using a data acquisition board with a 12-bit analog to digital converter. Sensitivities are measured at different operating temperatures also with different gas concentrations and film thickness. The high sensitivity is obtained for Sn (3000 $\AA$)/Pt (30 $\AA$) at 30$0^{\circ}C$ for 3 ppm. Response and recovery times were about 40 and 160 s, respectively. Repetition measurements showed very good results with $\pm$3% in full scale range.

• 한국세라믹학회지
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• 제43권8호
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• pp.486-491
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• 2006

A new $TiN-Ti_5Si_3$ bulk composite was synthesized from preceramic, inorganic polymer (methylpolysilsesquioxane) and $TiH_2$ filler powders via polymer pyrolysis. Using this process, ceramics with high melting points can be produced relatively easily to a near net shape. The $TiN-Ti_5Si_3$ composite oxidized slowly during heating to $1000^{\circ}C$. During heating at the temperatures of at 700 and $800^{\circ}C$, TiN oxidized to Rutile-$TiO_2$ whereas $Ti_5Si_3$ resisted to oxidation. The oxide scale formed consisted primarily of $TiO_2$ containing $Ti_5Si_3$.

• Bulletin of the Korean Chemical Society
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• 제31권4호
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• pp.905-909
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• 2010

Magnetic beads (Dynabeads$^{(R)}$) embedded in ~1 micron size polystyrene beads bearing surface carboxylic acid groups were modified with aminobenzyl ethylenediaminetetraacetic acid (ABEDTA) to concentrate or separate metal ions using pH gradients on micro and nano scales. The immobilization of ABEDTA was achieved by amide formation. The presence of the metal chelating functional group in the fully deprotonated form was confirmed by FT-IR. The chelation efficiency of beads was tested by determining metal ions in supernatant using GFAAS when pH gradients from 3 to 7. Mixtures of Cu and Mg and of Cd and Mn (at 10 ng/mL of metal) were separated as the difference in formation constant with the functional group of ABEDTA. The separation was repeated twice with relative standard deviation of <18%. A polydimethylsiloxane (PDMS) microchip column packed with EDTA-coated magnetic beads was optimized to concentrate metal ion for practical applications by eluting a Cu solution of micro scale at pH 3.

• 한국표면공학회지
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• 제28권3호
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• pp.142-151
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• 1995

In this research, a thin layer of Cr was coated on the pure Ni and Inconel 601 by PECVD (Plasma Enhanced Chemical Vapor Deposition) in order to study the effect of Cr on the oxidation behavior at high temperature. Cr coated Inconel 601, which was oxidized at $1100^{\circ}C$ for 24 hours, formed a protective $Cr_2O_3$ oxide layer and the resistance to isothermai oxidation was improved. On the other hand, oxidation resistance of Cr coated Inconel 601 at 100$0^{\circ}C$ was not significantly improved, probably due to the formation or insufficient $Cr_2O_3$ layer. But, when oxidized at $1000^{\circ}C$ and $1100^{\circ}C$ for 100 hours, Cr coated Inconel 601 improved isothermal oxidation resistance by the formation of continuous $Cr_2O_3$ external scale and by the development of $Al_2O_3$ subscales. Cr coated Ni formed inner layer of $Cr_2O_3$ within almost pure NiO, which provided additional cation vacancies, thus increasing the mobility of Ni ions in this region. It is believed that this doping effect resulted in an increase in the observed oxidation rate compared with pure Ni and did not improve the oxidation resistance.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.547-548
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• 2006

In order to realize the commercial application of HTSC materials, it is necessary to develop the fabrication process of high Tc oxide superconductor materials with desired shape and for practical application and high critical current density as well as good mechanical strength which can withstand high lorenz force generated at high magnetic field. Much studies have been concentrated to develop the fabrication technique for high critical current density but still there are a lot of gap which should be overcome for large scale application of HTSC materials at liquid nitrogen temperature. Recently some new fabrication techniques have been developed for YBaCuO bulk superconductor with high mechanical strength and critical current density. In this project, the establishment of fabrication condition and additive effects of second elements were examined so as to improve the related properties to the practical use of YBaCuO superconductor, and we reported the production of the YBaCuO high Tc superconductor by the pyrolysis method.

• 소성∙가공
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• 제12권7호
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• pp.640-646
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• 2003

The nanoprobe based on lithography, mainly represented by SPM based technologies, has been recognized as potential application to fabricate the surface nanostructures because of its operational versatility and simplicity. The objective of the work is to suggest new mastless pattern fabrication technique using the combination of machining by nanoindenter and KOH wet etching. The scratch option of the nanoindenter is a very promising method for obtaining nanometer scale features on a large size specimen because it has a very wide working area and load range. Sample line patterns were machined on a silicon surface, which has a native oxide on it, by constant load scratch (CLS) of the Nanoindenter with a Berkovich diamond tip, and they were etched in KOH solutions to investigate chemical characteristics of the machined silicon surface. After the etching process, the convex structure was made because of masking effect of the affected layer generated by nano-scratch. On the basis of this fact, some line patterns with convex structures were fabricated. Achieved patterns can be used as a mold that will be used for mass production processes such as nanoimprint or PDMS molding process. All morphological data of scratch traces were scanned using atomic force microscope (AFM).

• 한국해양바이오학회지
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• 제5권4호
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• pp.8-14
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• 2011

Although marine living organism contains a numerious number of compounds, it is difficult to collect these compounds in a large scale for medicinal application. However, in recent years, several bioactive compounds isolated from marine macroalgae have been proved to be able to provide potential sources for development of medicinal products because they can be obtained in large amount from marine. A number of studies have reported a variety of effects of marine macroalgae but a few anti-inflammatory activity of marine macroalgae have recently been published. Herein, we reviewed novel anti-inflammatory compounds recently isolated from marine brown algae, green algae and red algae. From this survey, in particular, some compounds contained in edible macroalgae exert anti-inflammatory effects with inhibition on cyclooxygenase-2 (COX-2), inducible nitric oxide synthase(iNOS) and matrix metalloproteinases (MMPs) activity regulated by nuclear factor-kappa B transcription factor that play a key role in cancer as well as inflammation, demonstrating to be able to potentially apply to development of anti-inflammatory agent for chemoprevention of cancer. Furthermore, some macroalgae and their compounds with both excellent anti-inflammatory activity and very low toxicity can select a potential candidates capable of preventing or treating several chronic inflammation such as colitis, hepatitis and gastritis, leading to cancer.

• 한국표면공학회지
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• 제32권1호
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• pp.67-77
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• 1999

The Ni base superalloy Mar-M247 substrate was aluminized or aluminized after boronizing by the pack cementation under Ar atmosphere. The hot corrosion resistance and after-heat-treatment effect of aluminized specimens were studied by the cyclic hot corrosion test in $Na_2SO_4$-NaCl molten salt. XRD analysis showed that the $Ni_2Al_3$ phase was formed between the coated layer and substrate below 1273K but the NiAl phase above 1273K. The peak of the NiAl phase was developed after heat treatment. Corrosion test showed that corrosion resistance of the specimen with the NiAl phase was better than that with the $Ni_2Al_3$ phase. Corrosion resistance could be improved by heat treatment to form ductile NiAl phase, where cracks were not formed by thermal shock on coating layer. Moreover, it appeared that heat treatment played a role to improve corrosion resistance of Al diffusion coating above 1273K. The existence of boron in the Al diffusion coating layer obstructed outwared diffusion of Cr from the substrate, and it influenced on corrosion resistance of the coating layer by weakening adherence of the oxide scale.