• Journal of the Society of Cosmetic Scientists of Korea
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• v.33 no.1 s.60
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• pp.23-28
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• 2007

Ascorbic acid (vitamin C, AsA) has been known as a strong reducing agent and is supposed to retard the synthesis of melanin pigment. A main problem that arose in using vitamin C in cosmetic formulation was its poor stability and low skin permeability, which result in low lightening efficacy in clinical trials. In this study, iontophoretic gel patch with flexible thin layer battery was employed in order to enhance skin permeation of vitamin c derivative (ascorbyl glucoside, AsAG) and to increase its lightening efficacy. in vitro iontophoretic skin permeation and stability of AsAG, safety and clinical lightening efficacy of iontophoretic patch containing 2% AsAG solution were examined. A optimun current of ionthophoretic patch for korean women was 0.1 mA, considering the skin permeability and skin irritation of consumers. We suggest that iontophoretic gel patch could be a safe system for enhancing the skin permeation of AsAG and lightning efficacy.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.222-222
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• 2010

Transparent semiconductor oxide thin films have been attracting considerable attention as potential channel layers in thin film transistors (TFTs) owing to their several advantageous electrical and optical characteristics such as high mobility, high stability, and transparency. TFTs with ZnO or similar metal oxide semiconductor thin films as the active layer have already been developed for use in active matrix organic light emitting diode (AMOLED). Of late, there have been several reports on TFTs fabricated with InZnO, AlZnSnO, InGaZnO, or other metal oxide semiconductor thin films as the active channel layer. These newly developed TFTs were expected to have better electrical characteristics than ZnO TFTs. In fact, results of these investigations have shown that TFTs with the new multi-component material have excellent electrical properties. In this work, we present TFTs with inverted coplanar geometry and with a novel HfInZnO active layer co-sputtered at room temperature. These TFTs are meant for use in low voltage, battery-operated mobile and flexible devices. Overall, the TFTs showed good performance: the low sub-threshold swing was low and the $I_{on/off}$ ratio was high.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.19.1-19.1
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• 2010

The process of manufacturing printed electronics using printing technology is attracting attention because its process cost is lower than that of the conventional semiconductor process. This technology, which offers both a lower cost and higher productivity, can be applied in the production of organic TFT (thin film transistor), solar cell, RFID(radio frequency identification) tag, printed battery, E-paper, touch screen panel, black matrix for LCD(liquid crystal display), flexible display, and so forth. In general, in order to implement printed electronics, narrow width and gap printing, registration of multi-layer printing by several printing units, and printing accuracy of under $20\;{\mu}m$ are all required. These electronic products require high precision to the degree of tens of microns - in a large area with flexible material, and mass productivity at low cost. As such, the roll-to-roll printing process is attracting attention as a mass production system for these printed electronic devices. For the commercialization of this process, two basic electronic ink technologies, such as conductive ink and polymers, and printing equipment have to be developed. Therefore, this paper addressed basis design and test to develop fine patterning equipment employing the roll-to-roll printing equipment and electronic ink.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.15.2-15.2
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• 2009

Manufacturing of printed electronics using printing technology has begun to get into the hot issue in many ways due to the low cost effectiveness to existing semi-conductor process. This technology with both low cost and high productivity, can be applied in the production of organic thin film transistor (OTFT), solar cell, radio frequency identification (RFID) tag, printed battery, E-paper, touch screen panel, black matrix for liquid crystal display (LCD), flexible display, and so forth. The emerging technology to manufacture the products in mass production is roll-to-roll printing technology which is a manufacturing method by printings of multi-layered patterns composed of semi-conductive, dielectric and conductive layers. In contrary to the conventional printing machines in which printing precision is about $50~100{\mu}m$, the printing machines for printed electronics should have a precision under $30{\mu}m$. In general, in order to implement printed electronics, narrow width and gap printing, register of multi-layer printing by several printing units, and printing accuracy of under $30{\mu}m$ are all required. We developed the roll-to-roll printing equipment used for printed electronics, which is composed of un-winder, re-winder, tension measurement system, feeding units, dancer systems, guide unit, printing unit, vision system, dryer units, and various auxiliary devices. The equipment is designed based on cantilever type in which all rollers except printing ones have cantilever types, which could give more accurate machine precision as well as convenience for changing rollers and observing the process.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.108-109
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• 2012

This talk will begin with the demonstration of facile synthesis of silicon nanostructures using the magnesiothermic reduction on silica nanostructures prepared via self-assembly, which will be followed by the characterization results of their performance for energy storage. This talk will also report the fabrication and characterization of highly porous, stretchable, and conductive polymer nanocomposites embedded with carbon nanotubes (CNTs) for application in flexible lithium-ion batteries. It will be presented that the porous CNT-embedded PDMS nanocomposites are capable of good electrochemical performance with mechanical flexibility, suggesting these nanocomposites could be outstanding anode candidates for use in flexible lithium-ion batteries. Directed self-assembly (DSA) of block copolymers (BCPs) can generate uniform and periodic patterns within guiding templates, and has been one of the promising nanofabrication methodologies for resolving the resolution limit of optical lithography. BCP self-assembly processing is scalable and of low cost, and is well-suited for integration with existing semiconductor manufacturing techniques. This talk will introduce recent research results (of my research group) on the self-assembly of Si-containing block copolymers for the achievement of sub-10 nm resolution, fast pattern generation, transfer-printing capability onto nonplanar substrates, and device applications for nonvolatile memories. An extraordinarily facile nanofabrication approach that enables sub-10 nm resolutions through the synergic combination of nanotransfer printing (nTP) and DSA of block copolymers is also introduced. This simple printing method can be applied on oxides, metals, polymers, and non-planar substrates without pretreatments. This talk will also report the direct formation of ordered memristor nanostructures on metal and graphene electrodes by the self-assembly of Si-containing BCPs. This approach offers a practical pathway to fabricate high-density resistive memory devices without using high-cost lithography and pattern-transfer processes. Finally, this talk will present a novel approach that can relieve the power consumption issue of phase-change memories by incorporating a thin $SiO_x$ layer formed by BCP self-assembly, which locally blocks the contact between a heater electrode and a phase-change material and reduces the phase-change volume. The writing current decreases by 5 times (corresponding to a power reduction of 1/20) as the occupying area fraction of $SiO_x$ nanostructures varies.