• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.179-180
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• 2007

• Transactions of Materials Processing
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• v.15 no.1 s.82
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• pp.27-33
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• 2006

It is necessary to improve the pattern replication and birefringence in LGP(Light guide panel) for better optical performance. In the present paper, the effects of injection-compression and injection-press mode with normal injection mold on the distribution of transcription of pattern and birefringence were studied. It was found that the values of pattern replication was improved and the birefringence was reduced for the cases of low initial clamping force in injection-compression mode and for the cases of longer mold opening length in injection-press mode, repectively.

• Transactions of the Society of Information Storage Systems
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• v.6 no.1
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• pp.37-40
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• 2010

Fresnel lens is a kind of refractive optical lens with various advantages. It has nearly flat shaped optical lens that has small mass. Fresnel lens has number of applications in the compact optical systems. Recently, demands of high quality Fresnel lens for small size optical systems such as illumination units, compact imaging systems, display units, information storage systems, optical detecting units had increased rapidly. Conventional manufacturing process of high quality Fresnel lens is direct machining. However, it is not suitable for mass production because of high cost and long cycle time. Replication method can provide cost effective mass production process. However, there are various issues about replication of Fresnel lens. Fresnel lens has number of sharp blade shape prism. In the replication process, this blade shape causes defects that can affect optical efficiency. In this study, replication processes; injection molding process and UV imprinting process, were developed and evaluated using Fresnel lens that has maximum pattern height of $250\;{\mu}m$ and aspect ratio of 1.5.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1532-1536
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• 2007

A plastic substrate with tiny rectangular pillars less than 100nm is injection molded to study pattern replication in injection molding. The size of the substrate is 50mm ${\times}$ 50mm and 1mm thick. The substrate has 9 patterned areas of which size is 2mm ${\times}$ 2mm respectively. The lengths of the pillars are 50nm, 100nm, 150nm and 200nm and the width and height are 50nm and about 100nm respectively. A pattern master is fabricated by e-beam writing using positive PR(photo resist) and then a nickel stamper replicated from the PR master by nickel electro-plating. Cr is deposited on the PR pattern master before nickel electro-plating as a conducting layer. Using this nickel stamper, several injection molding experiments are done to investigate effects of the injection molding parameters such as mold temperature, injection rate, packing pressure or pattern location on the replication of the patterns under 100nm.

• Biomedical Science Letters
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• v.17 no.3
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• pp.185-190
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• 2011

Adenovirus type 5 (Ad5) vectors have been used for gene transfer to a wide variety of cell types in vivo and in vitro. The advantages of adenovirus vectors include the high titer of virus readily obtained in large scale preparations, their ability to transduce dividing and non dividing cells, and the high level of transgene expression. Since adenovirus vectors do not integrate in host cell DNA, there is a lack of insertional mutagenesis. However, many human tumor cells lack expression of the adenovirus 5 receptors and contain areas of hypoxia. In order to identify the pattern of replication and gene expression of oncolytic adenovirus in hypoxic condition, multiple different fiber modified Ads (Ad5F/S11, Ad5F/S35, Ad5F/K7, Ad5F/K21, and Ad5F/RGD) was compared. The replication of all fiber modified adenovirus was inhibited in hypoxic condition in HEK 293 cells, but gene expression has variety on different tumor cell lines and the level of coxackievirus and adenovirus receptor (CAR) expression. These data suggest that CAR expression pattern and hypoxic condition of tumor are considered for optimal oncolytic adenovirus application.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.368-368
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• 2006

Micro-molded parts can be defined as parts with microgram weight, parts with micro-structured surface, and parts with micro-precision. In this study, various micro-scale molded parts for various polymers were produced by using a precision micro-molding machine. Molded parts with nano-structure surface were also produced to analyze the effect of molding conditions on replication of surface pattern and higher-order structure development of molded parts. Replication of molded parts was influenced by material properties, molding conditions and size of surface pattern. Higher-order structure of molded parts was investigated by using polarized microscope. Skin-shear-core regions inside the molded parts were observed and shear region affected to surface replication.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.151-152
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.901-902
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• 2009

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.5
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• pp.624-631
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• 2004

In this paper, new replication techniques fur a metal microcomponent having a real 3D shape were introduced. Helical gear was selected as one of a real 3D microcomponents for this study. The helical gear, which was made of photo-curable resin, was fabricated as a master pattern by microstereolithography technology. Then, a silicone rubber mold was fabricated from the master pattern. Lastly, a final bismuth alloy pattern was transferred from the silicone rubber mold by the microcasting process. In this paper, the replication technique is described in detail from the master pattern to the final pattern with some investigation on factors related to the technique.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.1
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• pp.51-57
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• 2014

Ultrasonic imprinting is a novel process for replicating micropatterns on thermoplastic polymer substrates with low energy consumption and short cycle time. The polymer substrate is softened by the frictional heat and repetitive deformation energy under ultrasonic excitation; thus, a number of micropatterns are replicated on the softened polymer substrate. In the present work, the effect of mold temperature on the replication characteristics of ultrasonic imprinting is investigated. The temperature change in the patterned region is measured by varying the mold temperature. Numerical simulation is then performed for investigating pattern replication characteristics under various mold temperatures. In addition, pattern replication ratio and uniformity are compared through various experimental measurements. Through the results of these comparisons, it is found that the mold temperature has a significant positive effect on the replication characteristics of ultrasonic imprinting.