• Transactions of Materials Processing
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• v.22 no.6
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• pp.310-316
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• 2013

Recently, numerical predictions of surface deflection based on curvature analysis have been developed. In the current study, a measure of surface deflection is proposed as the maximum variation of curvature difference between the panel and the tool in order to account for surfaces that have high curvature. The current study focused on the assessment of accuracy for the surface deflection prediction with the consideration of planar anisotropy. As an example, a shallow rectangular drawn part with rectangular embossing was considered. In terms of the proposed surface deflection measure, the maximum variation of curvature difference, the prediction with a planar anisotropic model shows better correspondence with experiment than the one using a normal anisotropic model.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.37-40
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• 2003

This present paper mainly contains adhesion part disconnection type exposure composition waterproof method using embossing PVC sheet. The existing polymer resin coating and sheet waterproofing construction method have, however, some weak point such as being decrease life cycle of concrete with water leaking from materials be affected by crack and movement dash bond concrete through the whole-adhere construction. Above the reason, this paper has particular method increasing crack-defending performance from stress occurred concrete movement by part disconnection, adds maintain waterproofing performance subordinate sheet, that can be contributed a convenience of maintenance which is decreasing industrial waste and repair construction cycle through the part repair in case of leaking water.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.1
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• pp.99-105
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• 2010

This study was performed to solve the breaking problem in the fine blanking(FB) process of sector gears for car seat recliner using nickel chrome molybdenum steel(SNCM220) plate. The optimal design of embossing circle is changed to oval with labors' experiences and finite element analysis. The maximum principal stress and effective strain in a forming process are analyzed by commercial finite element software to solve the problems in embossing stage of FB process. As a result of FE analysis, the maximum principal stress in forming is lower than yield point of material. It is shown from experiments in the modified die that the formed gear does not break in embossing stage.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.26.1-26
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• 2003

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.669-670
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• 2006

• Journal of the Korean Vacuum Society
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• v.13 no.1
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• pp.34-38
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• 2004

Hot embossing master is indispensable for the fabrication of polymeric optical waveguides using hot embossing technology. Sidewall roughness of silicon master is directly related to optical loss of optical waveguides In this paper, a silicon master was fabricated by using a deep-RIE process. Additionally, thermal oxidation followed by oxide removal was carried out to minimize etched Si sidewall roughness. Thermal oxidation and oxide removal were performed with $H_2O_2$ atmosphere at $1050^{\circ}C$ and $NH_4$F:HF=6:l BOE, respectively, for the oxide thickness of 400$\AA$, 1000$\AA$, 3000$\AA$, 4500$\AA$, 5600$\AA$ and 6200$\AA$. The sidewall roughness was characterized by SEM and SPM-AFH measurements. We found that the roughness was improved from 12nm (RMS) to 6nm (RMS) for the scalloped sidewall and from 162nm (RMS) to 39nm (RMS) for the vertical striation sidewall, respectively.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.217-220
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• 2009

This paper presents fabrication method of nano-structured PMMA substrates as well as evaluations of their optical transmittance. For anti-reflective surface, surface coating method had been conventionally used. However, it requires high cost, complicated process and post-processing times. In this study, we suggested the fabrication method of anti-reflective surface by the hot embossing process. Using the nano patterned master fabricated by anodic aluminum oxidation process. Anodic aluminum oxide(AAO) is widely used as templates or a molds for various applications such as carbon nano tube (CNT), nano rod and nano dots. Anodic aluminum oxidation process provides highly ordered regular nano-structures on the large area, while conventional pattering methods such as E-beam and FIB can fabricate arbitrary nano-structures on small area. We fabricated a porous alumina hole array with various inter-pore distance and pore diameter. In order to replicate nano-structures using alumina nano hole array patterns, we have carried out hot-embossing process with PMMA substrates. Finally the nano-structured PMMA substrates were fabricated and their optical transmittances were measured in order to evaluate the charateristivs of anti-reflection. Anti-reflective structure can be applied to various displays and automobile components.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.333-338
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• 2003

Nano-imprint lithography(NIL) is a polymer embossing technique, capable of transferring nano-scale patterns onto a thin film of thermoplastics such as polymethyl methacrylate(PMMA) using this parallel process. Feature size down 10 nm have been demonstrated. In NIL, the pattern is formed by displacing polymer material, which can be squeeze flow of a viscous liquid. Due to the size of the pattern, a thorough understood of the process through experiments may be very different. Therefore we nead to resort to numerical simulation on the embossing process. Generally, there are two ways of numerical simulation on nano-scale flow, namely top-down and bottom-up approach. Top-down approach is a way to simulate the flow assuming that polymer is a continuum. On the contrary, in the bottom-up approach, simulation is peformed using molecular dynamics(MD). However, as latter method is not feasible yet. we chose the top-down approach. For the numerical analysis, two dimensional moving grid was used since the moving grid can predict the flow front. Effects of surface tension as well as the slip at the boundary were also considered.

• Transactions of Materials Processing
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• v.21 no.3
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• pp.202-206
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• 2012

Marking is a process that engraves letters or a pattern onto the surface of sheet metal. During marking, it is important to set the proper working conditions for clarity of the letters. In this study a simple case for forming circular protrusions by half-piercing and embossing was initially attempted to determine the working conditions which gave good results with respect to shape accuracy. Corner-radius and flatness of circular protrusions made under several experimental conditions were measured and compared. It is shown that the precision of protrusions by half-piercing is superior to that of embossing, and the clearance between punch and die exerts a strong influence on the shape accuracy rather than the penetration percentage into the thickness of the sheet metal. The marking dies for "SNUT" letters, as an example, by applying the above results were manufactured with four different clearances. The working variables for the experiment were clearance and marking depth. For the very shallow depth of 0.1mm the letters were not clearly read. Letters marked under other conditions were easily distinguished with increasing marking depth. It was confirmed that the half-piercing technique with proper values of the working variables gives good quality for the marking of sheet metal.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.1
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• pp.62-67
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• 2016

This paper presents a silicon nanostructure array embedded in a polymer film. The silicon nanostructure array was fabricated by using basic microelectromechanical systems (MEMS) processes such as photolithography, reactive ion etching, and anisotropic KOH wet etching. The fabricated silicon nanostructure array was transferred into polymer substrates such as polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), and polycarbonate (PC) through the hot-embossing process. In order to determine the transfer conditions under which the silicon nanostructures do not fracture, hot-embossing experiments were performed at various temperatures, pressures, and pressing times. Transfer was successfully achieved with a pressure of 1 MPa and a temperature higher than the transition temperature for the three types of polymer substrates. The transferred silicon nanostructure array was electrically evaluated through measurements with a semiconductor parameter analyzer (SPA).