• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.198-201
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• 2004

This paper aims to investigate the micro-mechanical behaviour of tow geometry with forming pressures and densities of foams during the curing process of plain weave carbon fibre fabric prepregs onto polymer foams. In order to find out and compare deformation patterns between different forming conditions, tow parameters such as amplitude and crimp angle etc. are investigated. From the observation results, geometric difference in the tow architecture with respect to forming conditions and foam characteristics were found. To observe the micro-deformation of the fabric structure, appropriate specimens from carbon fibre-foam sandwich structures are sectioned and observed under the microscope.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.39-40
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• 2009

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.06a
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• pp.12-12
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• 2006

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.132-136
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• 2009

The importance and interests for saving of energy and cost in industry has been steadily grown up. Therefore, process optimization to reduce the processing step and energy is one of the most important things. The micro-alloyed steel of which post-heat-treatment is not necessary, has attractive points for high strength materials. However, for the application of non-heat-treated steel to structural parts, it is necessary to confirm the reliability of mechanical properties. In order to estimate mechanical properties. The microstructure, hardness, tensile strength, compressive strength and tensile fatigue strength of micro-alloyed steel having 900MPa tensile strength has been investigated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.560-563
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• 2004

Invar is a compound metal of Fe-Ni system and contain 36％ Ni. The most distinction characteristic of Invar is the coefficient of thermal expansion is 1.0 10$^{-6}$ /$^{\circ}C$. That is a tenth of general steel material. This low thermal expansion characteristic of Invar is applied to the missile, aircraft, monitor CRT and frontier display's shadow mask such as FED and OLED. The usage of the Invar shadow mask for display is increasing due to the requirement of larger size and flatness monitor. The Invar shadow mask is machined by two ways electro-forming and laser now. However the electro-forming takes a too long time and the laser machining is accompanied with Burr. In this study, PEMM(pulse electrochemical micro machining) is conducted to machine the micro hole to the Invar and 80${\mu}{\textrm}{m}$ hole was machined.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.36-39
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• 2004

Glass molding is an advantageous method to manufacture glass micro optical components. However, it is difficult to make Tungsten Carbide core for glass microlens array. We have developed novel method to fabricate Tungsten Carbide core for micro glass components using pressure forming. Silicon masters were fabricated by micro machining. Tungsten Carbide core was fabricated by pressure forming and sintering. And we made high quality surface of Tungsten Carbide core by using the magnetic-field-assisted polishing process.

• Transactions of Materials Processing
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• v.11 no.7
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• pp.581-588
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• 2002

Among the processes to produce micro lens, the process using press molding is a new technology to simplify the process, but it contains many unknown variables. The press-molding process proposed in this paper was simplified into two step process, the first step is the pressing to design the preform for glass element, the second step is the annealing to reduce the residual stress. It is important to estimate the amount of shrinkage of glass gob and the residual stress during process. It Is difficult to evaluate the process variables as mentioned above through the experiment. The influences due to process variables was evaluated by using FEM parametric analysis. The results in this paper can be applicable to produce micro lens.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.113-114
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• 2008

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.10a
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• pp.99-104
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• 1996

A proform for engine valve was designed by finite element method. In the preform design of engine valve, various initial billets are simulated for better preform to get sound final product. Here a preform is design to get desirable metal flow in the forming so that the final product has more uniform strain distribution. after forming. The analysis of the micro-structure of the value formed through the designed process was also performed and result was compared with that of simulation.

• Journal of the Korean Society for Heat Treatment
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• v.21 no.4
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• pp.183-188
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• 2008

Hot press forming allows geometrically complicated parts to be formed from sheet and the rapid cooling hardens them to extremely high strength. The main purpose of this research is to characterize Al coated layer in Al coated boron steel during hot press forming. For the hot press hardening experiment, test specimens were heated up to $810{\sim}930^{\circ}C$ and held for 3, 6 and 9 minutes, respectively. And then, some specimens were press hardened and others were air-cooled without any pressing for the comparison purpose. Al coated layer shows four distinct micro-structural regions of interest; diffusion zone, Al-Fe zone(I) low-Al zone(LAZ) and Al-Fe zone(II). Band-like LAZ is clearly shown at temperature ranges of $810{\sim}870^{\circ}C$ and sparsely dispersed at temperature higher than 900oC. The micro-cracking behavior in the Al coated layer during forming were also analyzed by bending and deep drawing tests. The strain concentration in softer LAZ is found to be closely related with micro-cracking and exfoliation in coated layer during forming.