• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2010년도 춘계학술발표대회
• /
• pp.19.2-19.2
• /
• 2010

Printed electronics using printing process has broadened in all respects such as electrics (lighting, batteries, solar cells etc) as well as electronics (OLED, LCD, E-paper, transistor etc). Copper is considered to be a promising alternative to silver for printed electronics, due to very high conductivity at a low price. However, Copper is easily oxidized, and its oxide is non-conductive. This is the highest hurdle for making copper inks, since the heat and humidity that occurs during ink making and printing simply accelerates the oxidation process. A variety of chemical treatments including organic capping agents and metallic coating have been used to slow this oxidation. We have established synthetic conditions of copper nanoparticles (CuNPs) which are resistant to oxidation and average diameter of 20 to 50nm. Specific resistivity should be less than $4\;{\mu}{\Omega}{\cdot}cm$ when sintered at lower temperature than $250^{\circ}C$ to be able to apply to conductive patterns of FPCBs using ink-jet printing. Through this study, the parameters to control average diameter of CuNPs were found to be the introduction of additive agent, the feeding rate of reducing agent, and reaction temperature. The CuNPs with various average diameters (58, 40, 26, 20nm) could be synthesized by controlling these parameters. The dispersed solution of CuNPs with an average size of 20 nm was made with nonpolar solvent containing 3 wt% of binder, and then coated onto glass substrate. After sintering the coated substrates at $250^{\circ}C$ for 30 minutes in nitrogen atmosphere, metallic copper film resulted in a specific resistivity of $4.2\;{\mu}{\Omega}{\cdot}cm$.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.2160-2163
• /
• 2005

Solid freeform fabrication (SFF) technology plays a major role in industry and represents a reasonable percentage of industrial rapid prototyping/tooling/manufacturing (RP/RT/RM) development applications. However, SFF technology still has long way to progress to achieve satisfactory process speed, surface finish and overall quality improvement of its application. Today, three dimensional printing (3DP) technique that is one of SFF technology is receiving many interests, and is applied by various fields. It can fabricate three dimensional objects of solid freeform with high speed and low cost using ink jet printing technology. However, need long curing time after manufacture completion. And it must do post-processing process necessarily to heighten strength of objects because strength of fabricated objects is very weak. Therefore, in this study, we proposed an improved 3DP process that can solve problems of conventional 3DP process. The general 3DP process is method to spout binder simply through printer head on powder, but proposed process is method to cure jetted UV resin by UV lamp after jet UV resin using printhead on powder. The hardening of resin is achieved strongly at early time by UV lamp in proposed method. So, the proposed process can fabricate three dimensional objects with high speed without any post-processing.

• 대한기계학회논문집B
• /
• 제31권1호
• /
• pp.51-61
• /
• 2007

This paper presents numerical and theoretical studies of acoustic wave interactions in slightly compressible liquids within piezoelectrically driven inkjet print heads. The interconnected flow channels may cause jet crosstalk, resulting in poor printing quality. It should be reduced by modifying the channel structure with the acoustic wave interactions considered. Compressible gas flow driven by the sudden movement of a top wall in the channel is calculated using Flow3D and is validated with the narrow gap theory. Limited compressibility model of the Flow3D is employed to calculate pressure waves of slightly compressible ink flow. It is found that reducing restrictor width can damp out the jet crosstalk by inhibiting the pressure wave propagation. The degree of crosstalk has been quantified using the maximum values of cross-correlations between neighboring channels and a critical channel dimension for acceptable crosstalk has been proposed. This finding is verified by drop visualization experiments using silicon-micromachined piezo inkjet print heads that are fabricated by our group.

• 한국인쇄학회지
• /
• 제18권1호
• /
• pp.35-45
• /
• 2000

Recently, as the prepress mainstream is changed to the digital workflow, various digital proofing systems such as high price dye sublimation printers and low price ink jet printers are widely used in printing industry. However, most of the digital proofing devices have lower resolution than analog proofing systems and differ with actual color presses in the color gamuts. Therefore, proper color compensations are needed for digital color proofing in order to match colors between the proofs and the press sheets. This study shows the application method of Look-up Table to the digital color proofer of Rainbow, the analog proofer of Matchprint-II, and an actual offset press is effective on the color compensations.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 추계학술대회 논문집
• /
• pp.203-203
• /
• 2009

Low temperature annealing for oxide TFTs including IGZO on PI substrate is the essential process to fabricate flexible display devices, since low heat-resistance on PI and PEN substrates limits the temperature range. Laser annealing is one of the promising candidates for low temperature process, and it has been used for various application in semiconductor and LCD fabrication. We irradiated laser to solution-based IGZO thin films on PI substrate were irradiated to laser beam, and investigated laser damage of PI layer. Based on transmittance analysis, wavelength(532nm) and scan speed(1000mm/s) is the optimized condition for laser irradiation about ink-Jet printed oxide TFTs on PI substrates.

• 한국가시화정보학회지
• /
• 제15권2호
• /
• pp.21-25
• /
• 2017

If a liquid droplet evaporates on a solid substrate, when it completely dries, it leaves a peculiar pattern, which depends on the composition of the liquid. Not only a single component liquid but also complex liquids are studied for a different purpose. In particular, a binary mixture droplet has been widely studied and used for an ink-jet printing technology. In this study, we focus on investigating to visualize the internal flow field of an ethanol-water mixture by varying a concentration ratio between two liquids. We measure the in-plane velocity vector fields and vorticities. We believe that this fundamental study about the internal flow field provides a basic idea to understand the dried pattern of the binary mixture droplet.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
• /
• pp.215-219
• /
• 2004

We reported two new techniques of barrier rib formation that are applicable to a variety of structures for high-efficiency PDPs suitable for mass-production [1]. These two methods are mold replication and direct glass sculpting. Especial progress has since been made in improving these methods to be more suitable for high-efficiency PDPs with the DelTA cell structure. This paper reports photolithographic fabrication methods for the masters used in mold replication. The masters for more complex barrier rib forms are easier to make with these methods. The paper also reports a process that combines the direct glass sculpting method with an ink-jet printing method of electrode formation.

• 한국공작기계학회논문집
• /
• 제13권3호
• /
• pp.61-67
• /
• 2004

In micro hole punching process the burr occurs inevitably, but the burr must be minimized in order to improve the quality and accuracy of the product. In this study, magnetic field-assisted polishing technique is applied to remove the burr which exists in nozzles for ink-jet printer head and proved to be a feasible for deburring by experiment. The deburring characteristics of sheet metals was investigated changing with polishing time and magnetic abrasive size. After the deburring, the burr size has remarkably reduced and roundness of the hole also has improved.

• 한국인쇄학회:학술대회논문집
• /
• 한국인쇄학회 2000년도 추계 학술 발표회 논문집
• /
• pp.17-28
• /
• 2000

Recently, as the prepress mainstream is changed to the digital workflow, various digital proofing systems such as high price dye sublimation printers and low price ink jet printers are widely used in printing industry. However, most of the digital proofing devices have lower resolutions than analog proofing systems and differ with actual color presses in the color gamuts. Therefore, proper color compensations are needed for digital color proofing in order to match color between the proofs and the press sheets. In this paper, we used 3-dimensional look-up table(LUT) and tetrahedral interpolation method for the color space conversion between the device independent color space(CIEXYZ or Lab) and the device dependent color space(CMY) to reduce the color differences between the original copy and digital color proofs and the press sheets.

• Korean Chemical Engineering Research
• /
• 제54권3호
• /
• pp.285-292
• /
• 2016

삼차원 프린팅(3D printing) 기술은 공학, 제조업, 교육, 예술, 그리고 바이오의학 같은 다양한 분야에 활용되고 있는 혁신적 기술이다. 프린팅 기술, 재료/생화학물질을 포함한 최근 기술의 진보는 생체적합성 물질, 세포, 지지체 성분의 3D 프린팅으로 복잡한 3D 기능성 조직과 장기를 제작할 수 있는 가능성을 보여주고 있다. 3D 바이오프린팅 기술은 신약 개발, 독성 연구를 위한 조직 모델의 제작에도 활용되고 있다. 3D 바이오프린팅 기술은 공학, 생체재료과학, 세포생물학, 생화학, 물리, 의학 같은 분야의 통섭이 필요한 연구 분야이다.