• Journal of Advanced Marine Engineering and Technology
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• v.28 no.8
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• pp.1286-1290
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• 2004

This paper describes the anti-corrosion system on underwater structures of ships. Metals and alloys have several positions in the series such as immunity, corrosion and passivity. The iron potential has to change from the corrosion position to the anodic protection or cathodic protection for preventing corrosion by providing corrosion protection system such as ICCP(Impressed Current Cathodic Protection). The purpose of ICCP system is to eliminate the rusting or corrosion, which occurs on metal immersed in water. The system includes a power supply unit, which consists of a transformer, a converter. a controller, etc. This paper presents the protection performance of ICCP under dynamic condition such as velocity. The variation of potential and current density with time and environment factors are also described Finally, the experimental results will be explained and analysed.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.42-47
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• 2004

Metallic glasses are amorphous meta-stable solids and are now being processed in bulk form suitable for structural applications including impact. Bulk metallic glasses have many unique mechanical properties such as high yield strength and fracture toughness, good corrosion and wear resistance that distinguish them from crystalline metals and alloys. However, only a few studies could be found mentioning the dynamic response and damage of metallic glasses under impact or shock loading. In this study, we employed a small explosive detonator for the dynamic indentation on a Zr-based bulk amorphous metal in order to evaluate the damage behavior of bulk amorphous metal under impact loading. These results were compared with those of spherical indentation under quasi-static and impact loading. The interface bonded specimens were adopted to observe the appearances of subsurface damage induced during indentation under different loading conditions.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.302-307
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• 2002

In electropolishing, the ion from the surface of the metal is eliminated by means of an electrical potential and current. Electropolishing is being generally known as a replacement for mechanical finishing. In addition to making a surface smoother, it is a more visible means of brightening, deburring, cleaning, stress-relieving and improving the physical characteristics of most metals and alloys. Therefore, the aim of the present study is to investigate the characteristic of electropolishing STS304 and A12024 in terms of current density, polishing time and electrode gap, etc.

• Journal of the Korean Society of Safety
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• v.8 no.4
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• pp.194-200
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• 1993

Grinding experiments for Al 7075 alloy were carried out to study the influence of grinding conditions and supply methods of grinding fluid on residual stress and surface roughness and grinding force. The residual stress was measured by an X-ray method. The supply method of grinding fluid with a guide nozzle has large decrease value of the tensile residual stress and of grinding force than a normal nozzle. In sparking out state of the grinding work, it is desirable to decrease the depth of cut and the workpiece feedrate for improving surface roughness and mechanical properties.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.2
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• pp.109-124
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• 2023

For decades, sputtering as a physical vapor deposition (PVD) method has been a widely used technique for film coating processes. The sputtering enables oxides, metals, alloys, nitrides, etc to be deposited on a wide variety of substrates from silicon wafers to polymer substrates. Meanwhile, transparent conductive oxides (TCOs) have played important roles as electrodes in electrical applications such as displays, sensors, solar cells, and thin-film transistors. TCO films fabricated through a sputtering process have a higher quality leading to an improved device performance than other films prepared with other methods. In this review, we discuss the mechanism of sputtering deposition and detail the TCO materials. Related technologies (processing conditions, materials, and applications) are introduced for electrical applications.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.10
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• pp.891-896
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• 2015

In order to protect the environment, using light material is becoming more and more attractive within the automobile industry. Aluminum alloys are the best and lightest metallic materials used in the automotive, electron, and aerospace industries. Al alloy and SGARC were joined by cold metal transfer (CMT) welding, using AlSiMn4 as a filler. Results showed that dissimilar metals from the Al 6000 series/SGARC could be successfully joined by CMT under proper processing parameters. The micro-hardness value of 125Hv was obtained at an interface.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.10 no.2
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• pp.21-30
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• 2001

Fiber reinforced materials have favorable mechanical properties. Moreover, the strength to weight ratios of this material is superior to those of most alloys. Comparing to the metals, it showed many other advantages as well, including non-corrosiveness, translucency and easy repair characteristic. Since, it has the potential for the chair-side and laboratory fabrication, it is not surprising that fiber reinforced composites offer the potential for use in various applications in dentistry. To make the well-fitted restorations, Fiber reinforced composite (FRC) has been suggested as an alternative framework material for the implant supported fixed prosthesis. Two fixed partial denture fabrication procedures were tried. Vectris fiber was pressed to the EsthetiCone gold cylinder on the implant positioned cast. And then, Targis were added on it. In the other method, we used the customized component using UCLA abutment. The beads for retaining the Vectris fiber were added on the abutment. If careful laboratory and clinical techniques were done, these two techniques would fulfill the demands of the esthetics and strength.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.352-355
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• 2007

Polycrystalline materials such as steels(BCC) and aluminum alloys(FCC) show the strain hardening and the strain rate hardening during the plastic deformation. The strain hardening is induced by deformation resistance of dislocation glide on some crystallographic systems and increase of the dislocation density on grain boundaries or inner grain. However, the phenomenon of the strain rate hardening is not demonstrated distinctly. In this paper, tensile tests for various strain rates are performed in the rage of $10^{-2}$ to $10^2s^{-1}$ then, specimens are extracted on the same strain position to investigate the microscopic behavior of deformed materials. The extracted specimen is investigated by using the electron backscattered diffraction(EBSD) and transmission electron microscopy(TEM) results which contain grain size, grain shape, aspect ratio and dislocation substructure.

• Corrosion Science and Technology
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• v.5 no.3
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• pp.106-111
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• 2006

Painting has protected metallic stack but the paint films may be degraded and corrosion problem can be arisen. To protect the painted metal stack, cathodic protection can be applied. If cathodic protection is applied to bare metal, only small area may be protected. However, if cathodic protection is applied to painted metal surface, large area can be protected and the lifetime of paint films can be extended. High corrosion resistant alloys were corroded at a Flue Gas Desulfurization (FGD) facility of power plant within a short period and thus cathodic protection can be used to protect these metals. On the base of computer simulation, if cathodic protection is applied to bare metal in a FGD environment, it was estimated that applied current could almost be spent to protect area near the anode. However, if cathodic protection is applied to high resistant-coated metal, the much larger area from the anode could be effectively protected.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3062-3067
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• 2007

HVOF thermal spray guns are now being widely used to produce protective coatings, on the surfaces of engineering components. HVOF technology employs a combustion process to heat the gas flow and melt the coating materials which are particles of metals, alloys or cermets. Particle flow which is accelerated to high velocities and combustion gas stream are deposited on a substrate. In order to obtain good quality coatings, the analysis of torch design must be performed. The reason is that the design parameters of torch influence gas dynamic behaviors. In this study, numerical analysis is performed to predict the gas dynamic behaviors in a HVOF thermal spray gun with various torch shapes. The CFD model is used to deduce the effect of changes in nozzle geometry on gas dynamics. Using a commercial code, FLUENT which uses Finite Volume Method and SIMPLE algorithm, governing equations have been solved for the pressure, velocity and temperature distributions in the HVOF thermal spray torch.