• Transactions of Materials Processing
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• v.22 no.7
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• pp.383-388
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• 2013

Metal flow of the beam blank during H-beam rolling was examined in order to correlate the rolling defects with the beam blank configuration. For this purpose, H-beam rolling was performed on the beam blank where stainless steel bolts were inserted as the marker at the web and flange. The positional variation of the marker was monitored at each rolling pass, and the result was compared with the 3D FEM simulation employing the point tracking function. The simulation results were reasonably agreed with the experimental within the error of 0.5~1mm on both web and flange of the H-beam. It is anticipated that the 3D FEM simulation employing the point tracking function provides the guidance information on analyzing the correlation between the rolling defects and the beam blank configuration in H-beam rolling.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1376-1380
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• 2005

In recent automotive industry, vehicle weight can be reduced by one-step forming of tailored blanks welded with two or more sheets of metal blanks. Tailored blank(TB) welding is a production method for blanks involving welding together materials of different quality, thickness, and coating, and has proved popular in fabrication automotive parts. This paper deals with the forming characteristics of mash seam welded tailored blanks. Using these forming characteristics, the bumper beam was developed using the mash seam welded tailored blank with the different thickness. We performed the forming simulation with respect to strain distribution on blank during the stamping of the bumper rail part. Based on these results, we made some stamping tryouts with selected types of blank designs to investigate the formability of tailored blank with different thickness. During the tryouts, we knew that it was important the BHF(Blank Holding Force). We obtained to reducing 10.5% weight and cost with adapting the bumper beam of automotive component using the tailored blank of mash seam welding.

• Proceedings of the KWS Conference
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• 2000.10a
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• pp.277-278
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• 2000

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.978-982
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• 2004

We present high aspect ratio 100nm-scale nickel stamper using e-beam lithography process and Cr/Qz mask for the injection molding process of nano grating patterns. Conventional photolithography blank mask (CrON/Cr/Qz) consists of quartz substrate, Cr layer of UV protection and CrON of anti-reflection layer. We have used Cr/Qz blank mask without anti-reflection layer of CrON which is non-conductive material and ebeam lithography process in order to simplify the nickel electroplating process. In nickel electroplating process, we have used Cr layer of UV protection as seed layer of nickel electroplating. Fabrication conditions of photolithography mask using e-beam lithography are optimized with respect to CrON/Cr/Qz blank mask. In this paper, we have optimized e-beam lithography process using Cr/Qz blank mask and fabricated nickel stamper using Cr seed layer. CrON/Cr/Qz blank mask and Cr/Qz blank mask require optimal e-beam dosage of $10.0{\mu}C/cm^2$ and $8.5{\mu}C/cm^2$, respectively. Finally, we have fabricated $116nm{\pm}6nm-width$ and $240nm{\pm}20nm-height$ nickel grating stamper for the injection molding pattern.

• Laser Solutions
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• v.2 no.1
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• pp.51-60
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• 1999

In this paper, weldability and formability of Tailored-Blank (TB) and the structural impact testing of bump beam were investigated to apply TB to automobile bumper beam. The optimal $CO_2$ laser welding condition for TB of SPFC and SPRC steel plates with different thicknesses was obtained. Before welding, the cross section of butt joint was prepared only by shearing without milling process. Real type bump beam was produced by two kind of forming processes such as roll-forming and press-forming, and the good formability of TB was obtained. Impact test results of bump by using pendulum and barrier were satisfied the impact regulation of bump. Finally. It may be confirmed that laser welded TB is well-balanced material in both weight reduction and production cost of automobile bump.

• Journal of the Semiconductor & Display Technology
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• v.3 no.2
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• pp.5-9
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• 2004

Microcircuit fabrication requires precise control of impurities in tiny regions of the silicon. These regions must be interconnected to create components and VLSI circuits. The patterns to define such regions are created by lithographic processes. In order to image features smaller than 70 nm, it is necessary to employ non-optical technology (or next generation lithography: NGL). One such NGL is extreme ultra-violet lithography (EUVL). EUVL transmits the pattern on the wafer surface after reflecting ultra-violet through mask pattern. If particles exist on the blank mask, it can't transmit the accurate pattern on the wafer and decrease the reflectivity. It is important to care the blank mask. We removed the particles on the wafer using focused ion beam (FIB). During removal, FIB beam caused damage the multi layer mask and it decreased the reflectivity. The relationship between particle removal and reflectivity is examined: i) transmission electron microscope (TEM) observation after particle removal, ii) reflectivity simulation. It is found that the image mode of FIB is more effective for particle removal than spot and bar mode.

• Journal of Welding and Joining
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• v.15 no.2
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• pp.54-63
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• 1997

For the purpose of establishing laser welding condition (laser power, welding speed and beam focus) and of evaluating tailored blanks for two kinds of thin steel sheets SPCC and SK5M using in the thin plate structure such as automobile, train, and so on, investigated their $CO^2$ laser weldability under various initial welding conditions. SPCC thin sheet showed good weldability under some welding conditions. But, high carbon steel sheet SK5M needed heat treatment after welding to obtain ductility of the welded joint. And next, tailored blank was tested through deep drawing to evaluate reliability of their obtained laser welding conditions. The forming depths by tailored blank were SPCC+SPCC=22-25mm and SK5M+SK5M=13-25mm.

• Proceedings of the Korean Society of Laser Processing Conference
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• 1998.11a
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• pp.16-19
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• 1998

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.03a
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• pp.159-164
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• 1996

For the purpose of establishing laser welding condition(laser power, welding speed and beam focus) and of evaluating tailor welded blank for three kinds of thin steel sheets of SPCC, SK5M and SUS304 using in the thin plate structure such as automobile, train and so on. Their $CO_2$ laser weldability were primarily tested under various welding condition. SPCC and SUS304 thin sheets showed good weldability under some welding condition. But, high carbon steel sheet SK5M needs heat treatment after welding to obtain higher tensile strength and ductility of the welded joint. And next, laser welding condition. Butt-welded specimens were not nearly broken at weld bead. However, base material were ruptured in the direction of circumference. The forming depths by tailor weld bead. However, base material were ruptured in the direction of circumference. The forming depths by tailor welded blank were SPCC+SPCC=22~25mm, SUS304+SUS304=25~43mm and SK5M+SK5M=13~17mm.

• Laser Solutions
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• v.1 no.1
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• pp.4-10
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• 1998

A basic research for tailored blank welding between mild steel and Zn-coated steel was carried out with $CO_2$ laser beam. The materials used in this work were low carbon steel sheet with a thickness of 1.2mm and Zn-coated steel sheet with the same thickness and 6.3$\mu$m Zn coating. Experiments were carried out by applying the Taguchi method in order to obtain optimized conditions for the application of tailored blank laser welding method in practical manufacturing process. Optical microscopy, XRD, SEM and TEM analysis were performed to observe microstructures and to determine the solidification mode of welded zone. Also mechanical properties were measured by microhardness test tensile test and Erichsen test in order to evaluate the formability of welded specimen. There was no trapped Zn in the fusion zone, and the phases in this region consisted of polygonal ferrite, quasi-polygonal ferrite, banitic ferrite and martensite. The elongation value of welded specimen was more than 80% of that value in the substrate and LDH value was more than 90% of that value in the substrate metal.