• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.953-954
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.119-120
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• 2011

• Journal of Biomedical Engineering Research
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• v.39 no.5
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• pp.188-207
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• 2018

Recently, three-dimensional (3D) printing of biological tissues and organ has become an attractive interdisciplinary research topic that combines a broad range of fields including engineering, biomaterials science, cell biology, physics, and medicine. The 3D bioprinting can be used to produce complex tissue engineering scaffolds based on computer designs obtained from patient-specific anatomical data. It is a powerful tool for building structures by printing cells together with matrix materials and biochemical factors in spatially predefined positions within confined 3D structures. In the field of the 3D bioprinting, three major categories of the 3D bioprinting include the stereolithography-based, inkjet-based, and dispensing-based bioprinting. Some of them have made significant process. Each technique has its own advantages and limitations. Compared with non-biological printing, the 3D bioprinting should consider additional complexities: biocompatibility, degradability of printing materials, cell types, cell growth, cell viability, and cell proliferation factors. Numerous 3D bioprinting technologies have been proposed, and some of them have been making great progress in printing several tissues including multilayered skin, cartilaginous structures, bone, vasculature even heart and liver. This review summarizes basic principles and key aspects of some frequently utilized printing technologies, and introduces current challenges, and prospects in the 3D bioprinting.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.3
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• pp.95-103
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• 2010

Roll to Roll (R2R) is one of the most promising production technologies in the printed electronics such as OLEDs, e-paper, backplanes, RFID because this technology can save production cost and increase production speed. Printed electronics includes various processes such as printing, drying, winding, unwinding, and so on. In printed electronics R2R system, air-flotation oven is employed for drying process. Therefore, it is essential to introduce efficient and fast drying process when printing is finished. This paper considers the analysis of drying process in R2R that involves hot air flow. Air-flotation oven consists of non-contact supports and drying of coated web materials such as plastic films and paper. In this paper, experimental results and numerical analysis of pressure-pad air bar are investigated. The aerodynamic characteristics of pressure-pad air bar are numerically calculated using computational fluid dynamics (CFD) approach. Then the measured values of the aerodynamic forces for air bars are compared with those of CFD analysis.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.32-34
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• 2007

전자산업 부문의 친환경 대응이 이슈화 되면서 전자기기의 대기전력 소비감소를 위한 연구가 지속적으로 수행되고 있다. 전자기기의 대표적인 전원공급장치인 Switched Mode Power Supply(SMPS)의 경우 부하기기의 대기모드 시 극도로 낮은 출력전력에서 고효율을 달성해야 하는 요구가 높다. 특히 많은 SMPS들이 부하기기의 요구에 의하여 다출력 컨버터로 설계되어 있는데, 이러한 다출력 구조에서 대기모드 시 불필요한 출력을 절체함과 동시에 저전력에서 고효율을 내기가 쉽지 않다. 또한 다출력 구조로 인한 Cross Regulation 문제를 극복해야 하는 과제가 있다. 따라서 본 논문에서는 단일 컨버터 혹은 복수의 컨버터로 구성되어 있는 다출력 컨버터에서 대기전력 개선을 위한 Secondary Side Post Regulator(SSPR), 전류모드, Power Sequence 제어기술을 제안하고, 대기전력과 더불어 SSPR의 Cross Regulation 특성 개선을 검토하였다. 그리고 제안한 기술이 구현된 다출력 구조의 110W와 270W급 SMPS를 제작하여 회로의 타당성 및 우수성을 검증하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1491-1494
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• 2005

We have studied ink-jet printing method for patterning conductive line on flexible plastic substrates. Synthesized silver nano-particles of ${\sim}$20nm were used for the conductive ink and the printed patterns exhibit a smooth line whose linewidth is below 100 ${\mu}m$. This ink-jet printing technique can be applied to flexible displays and electronics.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1135-1138
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• 2006

By ink-jet printing method, organic thin-film transistors (OTFTs) having soluble 6,13-bis (triisopropylsilylethynyl) pentacene (TIPS pentacene) as an active material were fabricated. The TIPS pentacene solution was made with chlorobenzene and anisole. The solutions were printed on poly (4-vinylphenol) (PVP) dielectric layers and source/drain electrodes by piezo-type heads for bottom contact OTFTs. The dielectric layers had untreated or HMDS-treated conditions. The chlorobenzene device showed the highest field effect mobility of $0.016\;cm^2/Vs$ and the anisole HMDS-treated device shows the highest $I_{on}/I_{off}$ ratio of $10^5$.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.557-558
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• 2006

In this paper, the hysteresis characteristics by bias stress in organic thin film transistors using inkjet printing were investigated. Electron trapping increased threshold voltage for positive gate bias stress and hole trapping decreased threshold voltage for negative gate bias stress. From these phenomena, highly reproducible measurement method which minimized threshold voltage shift by choosing the proper range of gate voltage was suggested. Using this measurement method, we found that electron trapping as well as hole trapping had important influence on hysteresis characteristics.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.563-563
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• 2012

We report a one-step fabrication of single-crystal organic nanowire arrays on substrates using a new direct printing method (liquid-bridge-mediated nanotransfer moulding, LB-nTM), which can simultaneously enable the synthesis, alignment and patterning of the nanowires using molecular ink solutions. Two- or three-dimensional complex structures of various single-crystal organic nanowires were directly fabricated over a large area with a successive process. The position of the nanowires can be aligned easily on complex structures because the mold is movable on substrates before drying the polar liquid layer, which acts as an adhesive lubricant. This efficient manufacturing method can produce a wide range of optoelectronic devices and integrated circuits with single-crystal organic nanowires.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.578-578
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• 2012

Graphene, a flat one-atom-thick two-dimensional layer of carbon atoms, is considered to be a promising candidate for nanoelectronics due to its exceptional electronic properties. Most of all, future nanoelectronics such as flexible displays and artificial electronic skins require low cost manufacturing process on flexible substrate to be integrated with high resolutions on large area. The solution based printing process can be applicable on plastic substrate at low temperature and also adequate for fabrication of electronics on large-area. The combination of printed electronics and graphene has allowed for the development of a variety of flexible electronic devices. As the first step of the study, we prepared the gate electrodes by printing onto the gate dielectric layer on PET substrate. We showed the performance of graphene field-effect transistor with electrohydrodynamic (EHD) inkjet-printed Ag gate electrodes.