• Journal of the Korean Vacuum Society
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• v.9 no.3
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• pp.267-272
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• 2000

Electroplating Cu was deposited on Si(100) wafer after seed Cu was deposited by sputtering first. TaN was deposited as a diffusion barrier before depositing the seed Cu. Electroplating Cu thin films show highly (111)-oriented microstructure for both before and after annealing at $450^{\circ}C$ for 30min and no copper silicide was detected in the same samples, which indicates that TaN barrier layer blocks well the Cu diffusion into silicon substrate. After annealing the electroplating Cu film up to $450^{\circ}C$, the Cu film became columnar from non-columnar, its grain size became larger about two times, and also defects density of stacking faults, twins and dislocations decreased greatly. Thus the heat treatment will improve significantly electromigration property caused by the grain boundary in the Cu thin films.

• Applied Microscopy
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• v.25 no.3
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• pp.75-81
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• 1995

The microstructural characterization of ternary $ZnS_{x}Se_{1-x}$(x=0.085) on GaAs(001) substrate grown up to $2{\mu}m\;at\;300^{\circ}C$ by molecular beam epitaxy(MBE) which has a single growth chamber was investigated by high resolution transmission electron microscope (HRTEM) working at 300 kV with point resolution of 0.18nm. The interface in the ZnSSe/GaAs specimen maintains a pseudomorphism with the substrate, but the epilayer has high density of stacking faults and moire fringes. The pits which had formed along <111> direction were found at the interface of ZnSSe/GaAs. The pits were responsible for producing defects in both epilayer and substrate. The wavy interface which has the difference of 15nm in height was found to maintain the pseudomorphism with the substrate and no stacking faults were found around the interface. However there exists faint and fine moire fringes in the epilayer near interface.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.91-91
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• 2003

Sliding wear behaviors of Inconel 600 and 690 were investigated at room temperature in air. In the present study, Archard's equation which has low reliability was modified. In the prediction of wear volume by Archard's equation, the reliabilities of Inconel 600 and 690 were about from 26.3% to 45.7% and from 69. l% to 88.6%, respectively, The sliding wear behaviors of Inconel 600 and 690 turned out to be influenced by their stacking fault energy, and the fact was confirmed by using TEM and micro-hardness test Based on experimental results, the wear coefficient was modified as a function of the sliding distance. The calculation with the modified wear equation showed that the reliability of Inconel 600 tested with 409 ferritic stainless steel increased from 45.7% to 93.4%.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.2
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• pp.95-102
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• 1994

Aluminum sheet application to automobile body panels has now become an important objective to meet the requirements of automobile weight reduction. As the Mg content in Al-Mg based alloys increased up to 7.19%, the strength and elongation increased. For instance. Al-7.19Mg alloy had a high strength of 305MPa and a high elongation of 35%. A study was also made to investigate the interrelation between grain size and tensile properties with varying the contents of Mg, Ti and Zr elements and annealing conditions. The yield stress decreased as the grain size increased, which increased the uniform elongation. The strain hardening exponents n increased as the Mg content increased, which depended on the increasing difficulties of the cross slip of dislocation.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.121-124
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• 2003

This paper shows shear wave behavior of CFRP(carton fiber reinforced plastics) composite laminates as a polar grid form to evaluate vibration pattern of ultrasonic transducers, which gives measured modelling fundamental contents of nondestructive evaluation. This modelling decomposes the transmission of a linearly polarized wave into orthogonal components through each ply of a laminate. It is found that a high probability shows between the model and measurement system in characterizing lay up of CFRP composite laminates. Also evaluating quantitatively the defects in CFRP laminates who found to be possible of normalized frequency obtained from 2D-FFT technique based on C-scan method. Thus, the technique is proven to be one of the useful means to evaluate any internal defect in CFRP composite laminates.

• Transactions of Materials Processing
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• v.18 no.6
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• pp.476-481
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• 2009

The present work demonstrates the mechanical and electrical responses of submicrocrystalline Cu-3%Ag alloy as a function of strain imposed by equal channel angular pressing(ECAP). From transmission electron microscope observation, the resulting microstructures of Cu-3%Ag alloy deformed by ECAP for 8-pass or more consist of reasonably fine, equiaxed grains without having a strong preferred orientation, suggesting that microstructure evolution is slower than that of pure-Al and its alloys owing to low stacking fault energy. The results of room temperature tension tests reveal that, as the amount of applied strain increases, the tensile strength of submicrocrystalline Cu-3%Ag alloy increases whereas losing both the ductility and the electrical conductivity. Such phenomenon can be explained based on microstructure featured by the non-equilibrium grain boundaries.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.393-396
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• 2009

The mechanical properties, press formability and texture of a TWIP steel were investigated. This steel combines both high strength and high ductility due to so called TWIP effect which are related to the microstructural changes. The formation of twins during deformation leads to an increase of its mechanical properties. In this study, the texture and mechanical properties evolutions of a TWIP steel subjected to tensile tests and press trials at room temperature were investigated in relation to the feasibility of the application to automotive body parts.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1510-1512
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• 2000

Due to the shrinking of the chip size and increasing of the complexity in the modern electronic devices. the defect of wafer are so important to decide the yield in the device process. The engineers has studied the wafer defects and the characteristics. They published lots of the experimental methods. I did an experiment the gettering effect of the defects due to the high temperature and the long time diffusion. Actually, As the thickness of the wafer backside polysilicon is thicker and the diffusion time is faster. the defects on the wafer are decreased. The polysilicon gram boundaries of the wafer backside played an important part as the defect gettering site.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.06a
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• pp.115-121
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• 2001

The wear test has been performed to evaluate the wear mechanism of steam generator (SG) tube materials against ferritic stainless steel in water environment. The wear rates of SG tube materials depend on the change of mechanical properties between contact surfaces during wear test. From the subsurface hardness test, Inconel 690 is more work-hardened than Inconel 600 even though these materials have similar hardness values before the wear test. Main cause is due to the difference of stacking fault energy with the chromium content. In water environment, wear mechanism is closely related with the continuous formation and fracture of deformation layers at the contact surfaces.

• Journal of the Korean institute of surface engineering
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• v.31 no.5
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• pp.297-303
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• 1998

The influences of vanadium addition on the cavitation erosion resistance pf Fe-Cr-Ni-Si-C hardfacing alloy were investigated using a vibratory apparatus up to 30 hrs. It was shown that 1wt.%V additioned alloy improved the resistance to cavitation damage. However, further increase in V content up to 2wt.% reduced the cavitation erosion resistance. It was considered that the addition of V developed the cavitation erosion resistance by reducing the stacking fault energy of Fe-Cr-Ni-Si-C alloy. However, the further increase in V content seemed to reduce the cavitation erosion resistance by increasing the matrix/carbide interfacial area, which was the preferential sites of the cavitation damage.