• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.3
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• pp.62-68
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• 2003

In this study, an experimental work was performed to mold tensile specimens by using the injection molding machine. Melt temperature, mold temperature and the mixed rate of recycled resin were selected as processing parameters for studing the effect of those condition on the shrinkage and weight of molded parts. As a result, the shrinkage was increased with the higher mold and melt temperature and It was more senstive to the change of mold temperature. On the other hand, the weight of molded parts was decreased with the increment of mold and melt temperature.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.1039-1040
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.819-820
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• 2008

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.04a
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• pp.15-19
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• 2003

Polymeric micro lens arrays with diameters of $13\~96\;{\mu}m$ fabricated using the micro-compression molding with electro formed mold inserts. In the present study, the electro forming process was used to make the metallic micro-mold insert for micro-molding of microlens array. The wettability property of the fabricated mold insert was examined by measuring the contact angle of the polymer melt on the mold insert. Microlenses were compression-molded with the fabricated mold insert. The effects of the molding temperature and wettability property on the replication quality of the molded lenses were analyzed experimentally.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.743-746
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• 2000

Plastic microlenses play an important role in reducing the size, weight, and the cost of the systems in the fields of optical data storage and optical communication. In the present study, plastic microlens arrays were fabricated using micro-compression molding process. The design and fabrication procedures for mold insert were simplified by using silicon instead of metal. A simple but effective micro compression molding process, which uses polymer powder, were developed for microlens fabrication. The governing process parameters were temperature and pressure histories and the micromolding process was controlled such that the various defects developing during molding process were minimized. The radius and magnification ratio of the fabricated microlens were $125{\mu}m$ and over 3.0, respectively.

• Transactions of the Society of Information Storage Systems
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• v.1 no.2
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• pp.192-196
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• 2005

In this paper, we investigated the possibility of replicating patterned media by nano-injection molding process with a metallic nano-stamper. The original nano-master was fabricated by E-beam lithography and ICP etching process. The metallic nano-stamper was fabricated using a nanoimprint lithography and nano-electroforming process. The nano-patterned substrate was replicated using a nano-injection molding process without additional etching process. In nano-injection molding process, since the solidified layer, generated during the polymer filling, deteriorates transcribability of nano patterns by preventing the polymer melt from filling the nano cavities, an injection-mold system was constructed to actively control the stamper surface temperature using MEMS heater and sensors. The replicated polymeric patterns using nano-injection molding process were as small as 50 nm in diameter, 150 nm in pitch, and 50 nm in depth. The replicated polymeric patterns can be applied to high density patterned media.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.8
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• pp.1242-1245
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• 2001

Plastic microlenses play an important role in reducing the size, weight, and the cost of the systems in the fields of optical data storage and optical communication. In the present study, plastic microlens arrays were fabricated using micro-compression molding process. The design and fabrication procedures for mold insert were simplified by using silicon instead of metal. A simple but effective micro compression molding process, which uses polymer powder, were developed for microlens fabrication. The governing process parameters were temperature and pressure histories and the micromolding process was controlled such that the various defects developing during molding process were minimized. The radius and magnification ratio of the fabricated microlens were 125$\mu\textrm{m}$ and over 3.0, respectively.

• Journal of the Korea Convergence Society
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• v.6 no.1
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• pp.43-48
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• 2015

We studied on the injection molding conditions of defect-free PMMA lens for surgical light. When the heat temperature of mold is low, more imperfect molding or weldlines and flow marks have showed. A defective lens depends on low fluidity of the PMMA resin and its temperature is high, a flexural strain has occurred. The longer cooling time of specimens, the more cracks have occurred due to resin crystallization. In this study, optimal molding conditions for defect-free PMMA lens is as follows. The heat temperature of core mold was 110 [$^{\circ}C$] and also the cooling time was 25 [sec]. PMMA materials can realized low expense to produce plastic optical lens and applications.

• Design & Manufacturing
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• v.17 no.4
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• pp.72-78
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• 2023

Injection molding is a process widely used in various industries because of its high production speed and ease of mass production during the plastic manufacturing process, and the product is molded by injecting molten plastic into the mold at high speed and pressure. Since process conditions such as resin and mold temperature mutually affect the process and the quality of the molded product, it is difficult to accurately predict quality through mathematical or statistical methods. Recently, studies to predict the quality of injection molded products by applying artificial neural networks, which are known to be very useful for analyzing nonlinear types of problems, are actively underway. In this study, structural optimization of neural networks was conducted by applying multi-task learning techniques according to the characteristics of the input and output parameters of the artificial neural network. A structure reflecting the characteristics of each process step was applied to the input parameters, and a structure reflecting the quality characteristics of the injection molded part was applied to the output parameters using multi-tasking learning. Building an artificial neural network to predict the three qualities (mass, diameter, height) of injection-molded product under six process conditions (melt temperature, mold temperature, injection speed, packing pressure, pacing time, cooling time) and comparing its performance with the existing neural network, we observed enhancements in prediction accuracy for mass, diameter, and height by approximately 69.38%, 24.87%, and 39.87%, respectively.

• Design & Manufacturing
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• v.1 no.1
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• pp.27-32
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• 2007

In the optical application demand for high quality lens is increasing. Plastics lenses are demanded more than glass lenses for large size lenses as well as micro-size lenses. It is difficult to apply typical straight cooling channels of injection mold to lens molding due to its non-uniform temperature distribution. In this study, we manufactured molds for plastic lenses with the conventional cooling channels and conformal cooling channels produced by the DMLS process. We evaluated cooling performance for the 2 molds by injection molding experiment. Also, uniformity of the temperature distribution was tested by infrared camera and temperature monitoring. We confirmed that the cooling performance and temperature uniformity with the conformal cooling channels is much improved from the ones with the conventional. The cooling time with the conformal cooling channels was reduced 30% compared with the conventional cooling channels.