• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.04a
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• pp.111-114
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• 2003

Compared to a conventional atomic layer deposition (ALD) grown Al203 film, Plasma enhanced ALD (PEALD) grown AION film was revealed to possess a large breakdown field, which is necessary for stable operation of thin film electroluminescent (TFEL) device. Also, AION is more stable than Al203 films grown by PEALD or by ALD after post-annealing process, which is inevitably required to improve luminance property of phosphor. Furthermore, AION films were applied to insulators of ZnS:Tb TFEL device. Resultant1y, they show better stability than ALD grown insulators under high electric field.

• Communications for Statistical Applications and Methods
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• v.10 no.1
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• pp.203-210
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• 2003

In a standard Metropolis-type Monte Carlo simulation, the proposal distribution cannot be easily adapted to "local dynamics" of the target distribution. To overcome some of these difficulties, Duane et al. (1987) introduced the method of hybrid Monte Carlo(HMC) which combines the basic idea of molecular dynamics and the Metropolis acceptance-rejection rule to produce Monte Carlo samples from a given target distribution. In this paper, using the HMC within Gibbs sampler, an asymptotical estimate of the smoothing mean and a general solution to state space modeling in Bayesian framework is obtaineds obtained.

• Journal of the Korean institute of surface engineering
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• v.52 no.4
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• pp.203-210
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• 2019

In this work, anodizing behavior of 6xxx series aluminum alloys was studied under constant current density and constant voltage conditions in 20% sulfuric acid solution by V-t curves, I-t curves, thickness measurement, observations of surface appearance and cross-sectional observation of anodizing films. The film growth rate of the anodizing films on Al6063, Al6061 and Al6082 obtained at 20 V were $0.63{\mu}m/min$. $0.46{\mu}m/min$ and $0.38{\mu}m/min$, respectively. Time to the initiation of imperfections at the oxide/substrate interface under constant current condition was shortened and colors of anodizing films became darker with the amount of alloying elements in 6xxx series aluminum alloys. Based upon the experimental results obtained in this work, it is concluded that maximum anodizing film thickness without interfacial defects is reduced with increasing amount of alloying elements and brighter anodizing films can be obtained by decreasing amount of alloying elements in the aluminum alloys.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.3
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• pp.203-207
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• 1998

After etching Al-Cu alloy films using $SiCl_4/Cl_2/He/CHF_3$ plasma, a corrosion phenomenon on the metal surface has been studied with XPS (X-ray photoelectron spectroscopy) and SEM (Scanning electron microscopy). In Al-Cu alloy system, the corrosion occurs rapidly on the etched surface by residual chlorine atoms. To prevent the corrosion, the $SF_6$ plasma treatment subsequent to the etch has been carried out. A passivation layer is formed by fluorine-related compounds on etched Al-Cu alloy surface after $SF_6$ treatment, and the layer suppresses effectively the corrosion on the surface as the RF power of $SF_6$ treatment increases. The corrosion could be suppressed successfully with $SF_6$ treatment in the RF power of 150watts.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.04a
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• pp.67-70
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• 2000

Mechanical properties of (10%$AI_20_3{\cdot}SiO_2$+5%Ni)/Al hybrid composites fabricated by the reaction squeeze casting were compared with those of (15%$AI_20_3{\cdot}SiO_2$)/Al composites. Intermetallic compound formed by reaction between molten aluminum and reinforcing powder was uniformly distributed in the Al matrix. These intermetallic compounds were identified as $Al_3$NI using EDS and X-ray diffraction analysis. Microhardness and flexural strength of hybrid composites were higher than that of (15%$AI_20_3{\cdot}SiO_2$)/Al Composite. In-Situ fracture tests were Conducted on (15%$AI_20_3{\cdot}SiO_2$)/Al Composites and (10%$AI_20_3{\cdot}SiO_2$+5%Ni)/Al hybrid composites to identify the microfracture process. It was identified from the in-situ fracture test of (10%$AI_20_3{\cdot}SiO_2$+5%Ni)/Al composites, microcracks were initiated mainly at the short fiber / matrix interfaces. As the loading was continued, the crack propagated mainly along the separated interfacial regions and the well developed shear bands. It was identified from the in-situ fracture test of (10%$AI_20_3{\cdot}SiO_2$+5%Ni)/Al hybrid composites, microcracks were initiated mainly by the short fiber/matrix interfacial debonding. The crack proceeded mainly through the intermetallic compound clusters

• Journal of the Korean Society for Heat Treatment
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• v.6 no.4
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• pp.194-203
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• 1993

Rapid solidified splats Al-(1, 3, 5Cr) Alloys were produced by atomization-splat quenching method. Effects of mechanical alloying on the structure and mechanical properties of rapidly solidified Al-(1, 3, 5)Cr alloys were studied. Degree of mechanical alloying of Al-(1, 3, 5)Cr alloys can be determined by observing the microstructural refinement, microhardness and microstructure of Al-(l, 3, 5)Cr splats during processing. In the initial stage of mechanical alloying of the Al-(1, 3, 5)Cr splats fracturing of the grain boundaries occured first, followed after fracturing of zone A regions. Saturation hardness of Al-(1, 3, 5)Cr alloys increased proportionally with increasing concentration of the solute (Cr). Age hardening was not observed in these alloys. Decomposition temperature of Al-1Cr splats after mechanical alloying was higher than that of Al-5Cr splats. The density of $Al_7$ Cr precipitates increased proportionally with increasing chromium content, as a result, there was a transition to finely and spherically dispersed phase after mechanical alloying.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.203-208
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• 2002

This paper deals with turning experiments of aluminium alloy using a single crystal diamond with round cutting edge. A face cutting was conducted using a special precision machine to study the characteristic phenomena in heavy cutting of aluminium alloy. In many cases, one of the most important matter on the surface integrity is about a damaged layer remaining just under the surface after machining. A machined surface roughness can be improved at a small geometrical surface roughness under special cutting conditions, even if a steady vibration exists between a tool and a workpiece.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1072-1075
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• 2001

$Al_2O_3$ ceramics are generally used as components in processing equipment, devices or machinery because it can perform some functions better than competing metals or polymers. Many of these applications rely on $Al_2O_3$ ceramics special electromagnetic properties, its relative chemical inertness, hardness, strength and its temperature capabilities. But $Al_2O_3$ ceramics are brittle materials, a fact that may cause problems and at the same time be helpful while machining with laser. This study described a basic study of the input parameters effect on the dimension of the microhole at the $Al_2O_3$ ceramics using Excimer laser. In the laser microhole machining of $Al_2O_3$ ceramics, major input parameters are pulse energy, pulse power, pulse frequency and pulse numbers. In conclusion, we can get a smaller microhole and diameter rate by an appropriate pulse energy, pulse frequency and pulse number.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.969-972
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• 2004

Al doped Zinc Oxide(ZnO:Al) films, which is widely used as a transparent conductor in optoelectronic devices such as solar cell, liquid crystal display, plasma display panel, thermal heater, and other sensors, were prepared by using the capacitively coupled DC magnetron sputtering method. In this paper the effect of doping amounts of $Al_2O_3$ on the electrical, optical and morphological properties were investigated experimentally, The results show that the structural and electrical properties of the film are highly affected by the doping. The optimum growth conditions were obtained for films doped with 2 wt% of Al203 which exhibit a resistivity of $8.5{\times}10^{-4}{\Omega}-cm$ associated with a transmittance of 91.7 % for 840 nm in film thickness in the wavelength range of the visible spectrum.

• Corrosion Science and Technology
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• v.23 no.3
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• pp.203-214
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• 2024

A heat exchanger is a device designed to transfer heat between two or more fluids. In a vehicle's thermal management system, Al heat exchangers play a critical role in controlling and managing heat for efficient and safe operation of the engine and other components. The fluid used to prevent heat exchangers from overheating the engine is mostly tap water. Heat exchange performance can be maintained at sub-zero temperatures using a solution mixed with antifreeze. Although the fluid flowing through the heat exchanger can reduce the temperature inside the engine, it also has various problems such as cavitation corrosion. Cavitation corrosion characteristics in tap water and corrosion characteristics were evaluated in this study when antifreeze was added for test specimens where AA4045 was cladded on the inner surface of AA3003 tubes of a fin-type heat exchanger. The cavitation corrosion resistance of AA3003 was found to be superior to that of AA4045 regardless of the test solution due to higher corrosion resistance and hardness of AA3003 than those of AA4045. The cavitation corrosion rate of Al alloys increased with the addition of antifreeze.