• Korean Journal of Materials Research
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• v.16 no.2
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• pp.99-105
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• 2006

This paper reports an improved bonding method using the IPA (isopropyl alcohol) assisted low-temperature bonding process for the PMMA (polymethylmethacrylate) micro CE (capillary electrophoresis) chip. There is a problem about channel deformations during the conventional processes such as thermal bonding and solvent bonding methods. The bonding test using an IPA showed good results without channel deformations over 4 inch PMMA wafer at $60^{\circ}C$ and 1.3 bar for 10 minutes. The mechanism of IPA bonding was attributed to the formation of a small amount of vaporized acetone made from the oxidized IPA which allows to solvent bonding. To verify the usefulness of the IPA assisted low-temperature bonding process, the PMMA micro CE chip which had a $45{\mu}m$ channel height was fabricated by hot embossing process. A functional test of the fabricated CE chip was demonstrated by the separation of fluorescein and dichlorofluorescein. Any leakage of liquids was not observed during the test and the electropherogram result was successfully achieved. An IPA assisted low-temperature bonding process could be an easy and effective way to fabricate the PMMA micro CE chip and would help to increase the yield.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.6
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• pp.997-1006
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• 2003

LICA technique evolved as a basic fabrication process fur micro-structure. The present report deals with the basic technological features in the sequence of the LIGA technique such as deep x-ray lithography(DXRL), electroplating, and moulding processes at Pohang Light Source (PLS). We designed 3-D structured master for fabrication of polymeric optical wavegude and manufactured polymeric optical wavegude with the same using hot embossing process. Polymeric optical waveguide could be produced with ${\pm}$ 1 $\mu\textrm{m}$ accuracy and good surface roughness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.571-572
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• 2006

RTP (rapid thermal pressing), one of micro-pattern replication techniques like hot embossing, is focused on achieving shorter cycle time. DFSS(Design for Six Sigma) has been applied in order to enhance the completeness of the development process for RTP system. According to DIDOV roadmap, we derived design concepts and subsequently decided the main performances, design factors, and components for RTP system. In the design process of RTP system using finite element analysis, it was realized that its structural characteristics affect large area replicability. Optimizing structural design factors, based on CAE, it was checked out that its large area replicability could be improved in a virtual test. Finally, we have a plan to validate the large area replicability of the developed RTP system, by performing micro-pattern replication tests with polymeric sheets.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.513-514
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.745-746
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• 2007

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.04a
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• pp.7-13
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• 2003

Microlens arrays were fabricated using a novel fabrication technology based on the exposure of a PMMA (Polymethylmethacrylate) sheet to deep X-rays and subsequent thermal treatment. X-ray irradiation causes the decrease of molecular weight of PMMA, which in turn decreases the glass transition temperature and consequently causes a net volume increase during the thermal cycle resulting in a swollen microlens. A new physical modeling and analyses for micro lens formation were presented according to experimental procedure. A simple analysis based on the new model is found to be capable of predicting the shapes of micro lens which depend on the thermal treatment. For the replication of micro lens arrays having various diameters with different foci on the same surface, the hot embossing and the microinjection molding processes has been successfully utilized with a mold insert that is fabricated by Ni-electroplating based on a PMMA microstructure of micro lenses. Fabricated microlenses showed good surface roughness with the order of 1nm.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.3
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• pp.299-305
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• 2015

In this paper, we propose a simple and low-cost fabrication method of polymer microlens using solvent-vapor-assisted reflow (SVAR). Metal molds for replication of polymer were fabricated using micro milling and the cylindrical shape of polymer was imprinted using hot-embossing process. The cylindrical shape of polymer was changed to hemispherical lens shape by SVAR. The characteristics of fabricated microlens were evaluated according to the condition of SVAR such as temperature and time. The focal length of polymer microlens could be controlled more easily in low-temperature and long-time condition than in high-temperature and short-time condition. That is, the level of concentrated light to focal point could be improved through the control of temperature and time. Also, we confirmed that toluene was more appropriate solvent than acetone in fabrication of PMMA polymer microlens using SVAR.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.12
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• pp.1139-1143
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• 2007

A simple method for the fabrication of 3D micro-nano hybrid patterns was presented. In conventional fabrication methods of the micro-nano hybrid patterns, micro-patterns were firstly fabricated and then nano-patterns were formatted on the micro-patterns. Moreover, these micro-nano hybrid patterns could be fabricated on the flat substrate. In this paper, we suggested the fabrication method of 3D micro-nano hybrid patterns using micro-indentation on the anodized aluminum substrate. Since diameter of the hemispherical nano-pattern can be controlled by electrolyte and applied voltage in the anodizing process, we can easily fabricated nano-patterns of diameter of loom to 300nm. Nano-patterns were firstly formatted on the aluminum substrate, and then micro-patterns were fabricated by deforming the nano-patterned aluminum substrate. Hemispherical nano-patterns of diameter of 150nm were fabricated by anodizing process, and then micro-pyramid patterns of the side-length of $50{\mu}m$ were formatted on the nano-patterns using micro-indentation. Finally we successfully replicated 3D micro-nano hybrid patterns by hot-embossing process. 3D micro-nano hybrid patterns can be applied to nano-photonic device and nano-biochip application.

• Design & Manufacturing
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• v.2 no.1
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• pp.45-50
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• 2008

Micro channel is to fabricate desired pattern on the polymer substrate by pressing the patterned mold against the substrate which is heated above the glass transition temperature, and it is a high throughput fabrication method for bio chip, optical microstructure, etc. due to the simultaneous large area patterning. However, the bad pattern fidelity in large area patterning is one of the obstacles to applying the hot embossing technology for mass production. In the present study, stamper of cross channel with width $100{\mu}m$ and height $50{\mu}m$ was manufactured using UV-LiGA process. Micro channel was manufactured using stamper manufactured in this study. Also replicability appliance was evaluated for micro channel and factors affected replicability were investigated using Taguchi method.

• Journal of Industrial Technology
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• v.39 no.1
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• pp.33-39
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• 2019

This paper addresses effects of nanoscale structures on structural colors of micropatterned transparent substrate by light diffraction. Structural colors is widely investigated because they present colors without any chemical pigments. Typically structural colors is presented by diffraction of light on a micropatterned surface or by multiple interference of light on a surface containing a periodic or quasi-periodic nano-structures. In this paper, each structural colors induced by quasi-periodic nano-structures, periodic micro-structures, and nano/micro dual structures is measured in order to investigate effects of nanoscale and microscale structures on structural colors in the transparent substrate. Using pre-fabricated pattern mold and hot-embossing process, nanoscale and microscale structures are replicated on the transparent PMMA(Poly methyl methacrylate) substrate. Nanoscale and microscale pattern molds are prepared by anodic oxidation process of aluminum sheet and by reactive ion etching process of silicon wafer, respectively. Structural colors are captured by digital camera, and their optical transmittance spectrum are measured by UV/visible spectrometer. From experimental results, we found that nano-structures provide monotonic colors by multiple interference, and micro-structures induce iridescent colors by diffraction of light. Structural colors is permanent and unchangeable, thus it can be used in various application field such as security, color filter and so on.