• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.1039-1042
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• 2000

This research will deal with Innovative manufacturing technology for milli-structure manufacturing technology which is located betweon the traditional manufacturing technology for macro-sized structure and the recently emerging manufacturing technology for micro-scaled structure such as MEMS. There are four fields in this research, which are micro-sheet metal forming technology, micro-bulk forming technology micro-molding technology and micro die making technology. As a project for new-technology in next generation, this research will be carried out through three terms and each term and be composed of three years.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.280-283
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• 2004

Micro-lens patterned micro-mold fabrication method for Light Guiding Plate(LGP), kernel part of LCD-BLU(Back Light Unit), was presented. Instead of erosion dot pattern for LGP optical design, micro-lens pattern, fabricated by LIGA-reflow process, was applied. Optical pattern design method was also developed not only for negative pattern LGP, but also positive pattern LGP. During injection molding process, experimental study was conducted to improve replication quality and brightness of ${\sim}50um$ micro-lens pattern mold. The effect of mold temperature for the replication quality of micro-lens array was studied.

• Journal of Power System Engineering
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• v.21 no.3
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• pp.37-44
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• 2017

In this study, failure analysis of the angular pin for molding machines to aluminum component molding was carried out. SM45C steel was used for the angular pin, it was surface hardened by the induction surface hardening heat treatment. The cross section of damaged angular pin was observed, and micro Vickers hardness value from the fractured part was measured. Brittle fracture was occurred from the fracture surface of angular pin, therefore, impact toughness value was evaluated by V-notch Charpy impact test. It was confirmed that the impact absorption energy was high when was tempered at a high temperature for a long time, and the toughness was slightly increased. Also, 2-parameter Weibull statistical analysis was investigated in order to evaluate the reliability of the measured micro Vickers hardness values and absorbed energy. The micro Vickers hardness and absorbed energy well followed a two-parameter Weibull probability distribution, respectively. The reverse design against angular pin was proposed as possible by using test results.

• Transactions of Materials Processing
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• v.15 no.9 s.90
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• pp.692-696
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• 2006

Micro fabrication of polymeric materials becomes increasingly important. And it is considered as a low-cost alternative to the silicon or glass-based Micro Electro-Mechanical System(MEMS) technologies. In the present study, micro channels were fabricated via LiGA(Lithographie, Galvanoformung, Abformung) process used for Capillary Electrophoresis(CE) chip. Taguchi method was applied to investigate the effects of process conditions in injection molding(melt temperature, injection speed, mold temperature and packing pressure) on the transcription characteristics of the micro channel. It was found that the skin layer disturbs a formation of micro channel. Furthermore, mold temperature and injection speed were two important factors to affect the replication characteristics of micro channel.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.115-118
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• 2002

The purpose of this paper is to design a pick-up for the small form factor optical disk drive and to fabricate a micro-compensatory lens for the pick-up using the micro-compression molding process. At design stage, the optical elements including the objective lens and the compensatory lens are miniaturized. The height of pick-up and free working distance are designed as 2mm and 0.2% respectively. To analyze the fabricated micro-compensatory lens, the system was analyzed using the surface profile of the fabricated micro-compensatory lens and CODE V which is commercial software. The RMS wave front aberration of the system using fabricated micro-compensatory lens is 0.01677λ which is lower than Marechal's criterion, 0.07λ.

• Tribology and Lubricants
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• v.32 no.6
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• pp.201-206
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• 2016

In this study, we attempt to produce a semi-elliptical riblet with a shark skin-like surface using wire electrical discharge machining (WEDM) and micro molding techniques. Our design for the production of the semi-elliptical mold includes an electrode, a winding roller, and a guide on the WEDM system. A replication mold with negative riblets is machined using WEDM, and a shark skin inspired surface with positive riblets is fabricated using a micro molding technique. For a comparison with the original shark skin, a shark skin replica is also produced using the micro molding technique directly from a shark skin template. Droplet contact angles on a flat surface, the shark skin replica, and the epoxy resin-based micro riblet shark skin-like surface are evaluated. The effect of a Teflon coating on the contact angles for the three different surfaces is also investigated. The results show the micro riblet with a shark skin-like surface has a similar contact angle as the shark skin replica, which means that the simplified riblet shark skin surface strongly influences the performance of wettability. This study confirms the effectiveness of using the WEDM method to prepare hydrophobic surfaces with diverse surface patterns.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.04a
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• pp.23-23
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.191-192
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• 2006

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.74-77
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• 2009

Demands for high quality and productivity of precision mechanical parts are increasing greatly nowadays due to the rapid growth of information technologies and convergence industries. Therefore, core technologies for fabrication of precision mechanical parts are the fundamental issues, which are the precision machining, micro powder injection molding technologies, MR polishing, micro polymer processes, micro actuation modules and so on. These technologies are directly related to the mass production of high functional devices and machineries. Therefore, this study investigates the fabrication technologies of micro precision molds for advanced devices for possible commercialization in a near future.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.111-114
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• 2005

Experimental and numerical studies were carried out in order to investigate the processability and the transcriptability of the injection molding of micro structures. For this purpose, we designed a mold insert having micro rib patterns on a relatively thick base part. Mold insert has a base of 2mm thickness, and has nine micro ribs on that base plate. Width and height of the rib are $300{\mu}m\;and\;1200{\mu}m$, respectively. We found a phenomenon similar to 'race tracking', due to 'hesitation' in the micro ribs. As the melt flows, it starts to cool down and melt front located in the ribs near the gate cannot penetrate further because the flow resistance is large in that almost frozen portion. When the base is totally filled, the melt front away from the gate is not frozen yet. Therefore, it flows back to the gate direction through the ribs. Consequently, transcriptability of the rib far from the gate is better. We also verified this phenomenon via numerical simulation. We further investigated the effects of processing conditions, such as flow rate, packing time, packing pressure, wall temperature and melt temperature, on the transcriptability. The most dominant factor that affects the flow pattern and the transcriptability of the micro rib is flow rate. High flow rate and high melt temperature enhance the transcriptability of micro rib structure. High packing time and high packing pressure result in insignificant dimensional variations of the rib. Numerical simulation also confirms that low flow rate causes a short shot of micro ribs and high wall temperature helps the filling of the micro ribs.