• Proceedings of the Korean Magnestics Society Conference
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• 2003.12a
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• pp.159-159
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• 2003

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.04a
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• pp.93-104
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• 2002

• Proceedings of the KWS Conference
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• 2003.05a
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• pp.75-77
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• 2003

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.573-573
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• 2006

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.572.2-572.2
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• 2006

• Journal of ILASS-Korea
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• v.13 no.4
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• pp.173-179
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• 2008

The current machinery and tools of secondary channel of the nuclear power plants were produced in the carbon-steel and low-alloy steel. What produced with the carbon-steel occurs wall thinning effect from flow accelerated corrosion by the fluid flow at high temperature, high pressure. Several nuclear power plants in Korea have experienced wall thinning damage in the area around the impingement baffle-installed. Wall thinning by flow accelerated corrosion occurs piping system, the heat exchanger, steam condenser and feedwater heaters etc,. Feedwater heaters of many nuclear power plants have recently experienced sever wall thinning damage, which will increase as operating time progress. This study describes the comparisons between the numerical results using the FLUENT code and experimental data of down scale model.

• Journal of the Korean institute of surface engineering
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• v.30 no.5
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• pp.310-319
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• 1997

The purpose of this study is to investigate the effect of the specific alloying elements in steel such as Cr, Ni and Cu, and surface roughness of substrate with two different FCS temperature zones in the CAL process on the phosphatability of the cold-rolled sheet used for the drum in order to improve the zinec phosphating property. Phosphatability is dependent of the surface oxide and roughness on the substrate and can be indirectly improved by increasing surface roughness of the steel sheet. Basically, in order to obtain the good phosphatability, the low concentration of the retained elements such as Cr, Ni and Cu among the steel alloy elements should be required. Phosphatability of substrate with high concentration instead of the retained elements and surface roughness, however, can be effectively improved instead of low FSC temperature.

• Korean Journal of Metals and Materials
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• v.50 no.4
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• pp.300-309
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• 2012

Low-carbon steels and a stainless steel were oxidized isothermally and cyclically between $1050^{\circ}C$ and $1200^{\circ}C$ for up to 100 min in air to find the effect of alloying elements of Si, Mn, Ni, and Cr on their oxidation. The most active alloying element of Si was scattered inside the oxide scale, at the scale-alloy interface and as internal oxide precipitates beneath the oxide scale. Manganese, which could not effectively improve the oxidation resistance, was rather uniformly distributed in the oxide scale. Nickel and chromium tended to present at the lower part of the oxide scale. Excessively thick porous scales formed on the low-carbon steels, whereas thin but non-adherent scales containing $Cr_2O_3$ formed on the stainless steel.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.5
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• pp.491-497
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• 2019

Dissimilar friction welding were produced using 15 mm diameter solid bar in superalloy(Alloy718) to chrome molybdenum steel(SCM440) to investigate their mechanical properties. Consequently, optimal welding conditions were n=2000 rpm, HP=60 MPa, UP=120 MPa, HT=10 sec and UT=10 sec when the metal loss(Mo) is 3.5 mm. Acoustic Emission(AE) technique was applied to analyze the dissimilar friction welding of Alloy718 and SCM440. The relationship between the AE parameters and dissimilar friction welding of both material was discussed. In the case of heating time of 6 sec, 10 sec, 14 sec and 20 sec, 5 AE events per 0.5 seconds and energy about $2.7{\times}10^{10}$ were exhibited in heating time. In upsetting time, resulting in various numbers of events per second and very low energy. The frequency range of the signal generated during the heating time was about 200 kHz. However, the upsetting time resulted in a wide range of signals from very low frequency to high frequency of 500 kHz due to rapid plasticity of the material.

• Journal of Power System Engineering
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• v.19 no.1
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• pp.64-69
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• 2015

Aluminum alloy is a material with a high strength-weight ratio and excellent thermal conductivity. It neither readily corrodes nor quickly weakens at low temperatures, but can be easily recycled. Because of these features, aluminum heat exchangers are widely used in aluminum alloy. In addition, the aluminum alloy used in other areas is expected to gradually increase. As a result, researchers have been continuously studying the cutting patterns of aluminium alloy. However, such studies are fewer than those on the cutting patterns of ordinary steel. Moreover, the research on ball endmilling with aluminium alloys has not received much attention. Therefore, in this study, an attempt was made to find the optimal cutting pattern among the seven cutting patterns for the machining of the commonly used aluminum alloy using ball endmilling for a heat exchanger. The optimal pattern was found by comparing the different shapes and surface roughness values produced by the seven patterns.