• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1547-1550
• /
• 2005

ISB panel, inner structured of metal in two skin and bonded, has inner structures which have low relative density, stiffness and strength with low weight of make improvement for that purpose. A kind of Inner structures have various structure types. In this paper, we have studied the Forming Limit Diagram(FLD), thickness variation and stress strain to dimple structure of sheet by analysis of Dynaform and LS-Dyna.

• Journal of Industrial Technology
• /
• v.29 no.B
• /
• pp.3-7
• /
• 2009

A cylindrical pin fin with inside fluid is optimized based on fixed fin volume by using the one dimensional analytic method. Heat loss from the fin and the pin fin radius for fixed fin volume is presented as a function of the fin length. Temperature variation of the fin with the variation of ambient and inside fluid convection characteristic numbers and fin base thickness is listed. The maximum heat loss at the practical fin length and corresponding optimum fin length and radius are presented as a function of fin base thickness, inside convection characteristic number, fin volume and ambient convection characteristic number. One of the results shows that the optimum pin fin shape becomes relatively fatter as the fin volume increases.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2004.10a
• /
• pp.342-345
• /
• 2004

A combination of deep drawing and cold forging process is tried to achieve near net shaping of automatic transmission part which has drum shape and thickness variation. It is key for successful shaping of the part to find out proper condition to combine two different forming methods. Finite element analysis can be utilized for that purpose effectively. Integrity, reliability, and durability of the part are improved by eliminating machining process. The developed process is applied in real manufacturing process successfully.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.19 no.3
• /
• pp.274-281
• /
• 2009

The carbon fiber epoxy composite material and aluminum have many advantages over other materials because of their high specific stiffness and good fatigue characteristics. Basically, the propeller shaft of automobile requires bending frequency of higher than 2,700 Nm and high natural frequency of higher than 9,200 rpm occurred by fast revolution. For this reason, natural frequency and torsion torque characteristics of hybrid shaft was studied in variation of its outer-diameter and thickness. Vibration and torque characteristics of hybrid shaft were compared by torsion tester, natural frequency experiments and FE analysis. Designed hybrid shaft satisfied its vibration and torque characteristics when its outer-diameter was 60 mm and thickness was 5 mm. Therefore, hybrid material enables to manufacture one piece structure hybrid propeller shaft rather than current two piece structure.

• 전기의세계
• /
• v.30 no.4
• /
• pp.227-230
• /
• 1981

The variation of sheet resistance and the reduction of masking oxide thickness with the flow rate of nitrogen gas has been measured in Boron predeposition process with Planar Diffusion source, BN-975. At 900.deg. C, the sheet resistance varied as much as 75% when the nitrogen flow rate was changed from 0.4 liters/min to 2.0 liters/min. At 975.deg. C, however, only 12% of sheet resistance variation was observed under the same flow rate change. The reduction of masking oxide thickness at 975.deg. C for a 5 min predeposition was 600 nm when the nitrogen flow rate was 0.4 liters/min. When the flow rate incresased to 1.9 liters/min, however, only 100nm of masking oxide was consumed in a similar predeposition process.

• Transactions of Materials Processing
• /
• v.14 no.5 s.77
• /
• pp.439-443
• /
• 2005

Deep drawing and cold forging processes are combined to achieve near net shape forming of automotive part which has not only drum shape but also thickness variation. It is important to find out proper intermediate shape where two totally different forming methods should be joined seamlessly. In the course of development of the combined process, finite element analysis can be utilized effectively to decide optimal position for transferring from the sheet metal work to the bulk forming. Because machining process is eliminated, significant improvement in integrity, reliability, and durability of the part is expected. The developed process combination could be applied in real manufacturing process successfully.

• Korean Journal of Materials Research
• /
• v.16 no.5
• /
• pp.308-311
• /
• 2006

The purpose of this study is to investigate the difference of the wafer nanotopography impact on the oxide-film thickness variation between the STI CMP using ceria slurry and STI CMP using fumed silica slurry. The nanotopography impact on the oxide-film thickness variation after STI CMP using ceria slurry is 2.8 times higher than that after STI CMP using fumed silica slurry. It is attributed that the STI CMP using ceria slurry follows non-Prestonian polishing behavior while that using fumed silica slurry follows Prestonian polishing behavior.

• Transactions on Electrical and Electronic Materials
• /
• v.3 no.4
• /
• pp.5-9
• /
• 2002

Chemical mechanical polishing (CMP) has become the preferred planarization method for multilevel interconnect technology due to its ability to achieve a high degree of feature level planarity. Especially, to achieve the higher density and greater performance, shallow trench isolation (STI)-CMP process has been attracted attention for multilevel interconnection as an essential isolation technology. Also, it was possible to apply the direct STI-CMP process without reverse moat etch step using high selectivity slurry (HSS). In this work, we determined the process margin with optimized process conditions to apply HSS STI-CMP process. Then, we evaluated the reliability and reproducibility of STI-CMP process through the optimal process conditions. The wafer-to-wafer thickness variation and day-by-day reproducibility of STI-CMP process after repeatable tests were investigated. Our experimental results show, quite acceptable and reproducible CMP results with a wafer-to-wafer thickness variation within 400$\AA$.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.25-30
• /
• 2004

In this paper, the compensation of interfacial scatter due to adhesive layer and adherend thickness ratio variation was applied to improve measuring precision by calculating ultrasonic attenuation coefficient in the Al/Epoxy dissimilar bonded components. The optimum condition of theoretical value and experimental measuring accuracy by the ultrasonic method in the Al/Epoxy dissimilar bonded components have been investigated. From the experimental results, we proposed a measurement method of the interfacial crack lengths by the ultrasonic attenuation coefficient and discussed it.

• Transactions of Materials Processing
• /
• v.17 no.8
• /
• pp.586-593
• /
• 2008

In warm press forming of magnesium alloy sheet, it is important to control the sheet temperature by heating the sheet in closed die. When forming a commercial AZ31 magnesium alloy sheets which are 0.5mm and 1.0mm thick, respectively, time arriving at target temperature and temperature variation in magnesium alloy sheet have been investigated. The deep drawing process with rectangular shape alone at the first stage and with both circular and rectangular shapes at the second stage was employed. At the first stage, through deep drawing process with rectangular shape alone according to various forming temperature($150{\sim}350^{\circ}C$) and velocity($0.1{\sim}1.0mm/s$), optimum forming condition was obtained. At the second stage, deep drawing process with the circular and rectangular shapes were performed following deep drawn square cups with Limited Drawing Height(LDH) obtained at the first stage. Here, clearance which is defined a gap between the die and the punch including sheet was set to ratio of 20, 40 and 100% to thickness in sheet. Accordingly, temperature, velocities, and clearances suitable for forming were suggested through investigating the thickness variation of the product.