• 한국표면공학회지
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• 제57권4호
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• pp.265-273
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• 2024

An amperometric sensor for measuring indole-3-acetic acid (IAA) was studied based on a screen-printed carbon electrode (SPCE) coated with a reduced graphene oxide composite electrocatalyst. The PEI-GO dispersion is uniformly formed through a nucleophilic substitution reaction between the active amine group of Polyethyleneimine (PEI) and the epoxide group exposed on the surface of graphene oxide. And The 3-dimensional PEI-rGO AG (Polyethyleneimine-reduced graphene oxide aerogel) complex was easily prepared through simple heat treatment of the combined PEI-GO dispersion. The proposed composite catalyst electrode, PEI-rGO AG/SPCE, showed a two linear relationship in the low and high concentrations in IAA detection, and the linear equation was I_pa = 0.2883C + 0.0883 (R²=0.9230) at low concentration and Ipa = 0.00464C + 0.6623 (R²=0.9894) at high concentration was proposed, and the detection limit was calculated to be 203.5nM±33.2nM. These results showed the applicability of the PEI-rGO AG composite catalyst as an electrode material for electrocatalysts for the detection of IAA.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.347.1-347.1
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• 2016

Screen printing is commonly used to form the electrode for crystalline silicon solar cells. However, it has caused high resistance and low aspect ratio, resulting in decrease of conversion efficiency. Accordingly, Ni/Cu/Ag plating method could be applied for crystalline silicon solar cells to reduce contact resistance. For Ni/Cu/Ag plating, laser ablation process is required to remove anti-reflection layers prior to the plating process, but laser ablation results in surface damage and then decrease of open-circuit voltage and cell efficiency. Another issue with plating process is ghost plating. Ghost plating occurred in the non-metallized region, resulting from pin-hole in anti-reflection layer. In this paper, we investigated the effect of Ni/Cu/Ag plating on the electrical properties, compared to screen printing method. In addition, phosphoric acid layer was spin-coated prior to laser ablation to minimize emitter damage by the laser. Phosphorous elements in phosphoric acid generated selective emitter throughout emitter layer during laser process. Then, KOH treatment was applied to remove surface damage by laser. At this step, amorphous silicon formed by laser ablation was recrystallized during firing process and remaining of amorphous silicon was removed by KOH treatment. As a result, electrical properties as Jsc, FF and efficiency were improved, but Voc was lower than screen printed solar cells because Voc was decreased due to surface damage by laser process. Accordingly, we expect that efficiency of solar cells could be improved by optimization of the process to remove surface damage.

• 한국세라믹학회지
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• 제39권5호
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• pp.467-472
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• 2002

다이아몬드 연마 필름(diamond lapping film)으로 긴 탄소나노튜브를 절단하고 이를 Scanning Electron Microscope(SEM)으로 관찰했다. 절단된 탄소나노튜브를 ${\alpha}$-terpineol을 용매로 ethyl cellulose를 바인더로 사용하여 제조한 페이스트를 스크린 프린팅과 주사 사출법으로 유리 기판에 도포하였다. 스크린 프린팅으로 인쇄된 선에 존재하는 절단된 탄소나노튜브를 기판에 대해 수직 배향을 시키기 위하여 사포, 다이아몬드 연마 필름을 사용하여 마찰시키거나 접착성이 있는 테이프를 이용하여 접촉시켰다가 분리 하는 방법을 시도하였다. SEM으로 탄소나노튜브의 배향 특성을 관찰한 결과 주사 사출법과 스크린 프린팅 후 다이아몬드 연마 필름을 사용하여 후처리하는 간편한 방법으로 탄소나노튜브의 우수한 수직배양이 이루어짐을 알 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1806-1809
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• 2008

Study that form micro pattern by direct ink jet printing method is getting attention recently. Direct ink jet printing spout fine droplet including nano metal particle by force or air pressure. There is reason which ink jet printing method is profitable especially in a various micro-patterning technology. It can embody patterns directly without complex process such as mask manufacture or screen-printing for existent lithography. In this study, research of a technology that ejects fine droplet form of Pico liter and forms metal micro pattern was carried with inkjet head of piezoelectricity drive system. Droplet established pattern while ejecting consecutively and move on the surface at the fixed speed. Patterns formed in ink are mixed with organic solvent and polymer that act as binder. So added thermal hardening process after evaporate organic solvent at isothermal after printing. I executed high frequency special quality estimation of CPW transmission line to confirm electrical property of manufactured circuit board. We tried a large area printing to confirm application possibility of an ink jet technology.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.20.2-20.2
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• 2010

Recently inkjet printing technology has been developed in the areas of low cost fabrication in environmentally friendly manufacturing processes. Although inkjet printing requires the interdisciplinary researches including development of materials, manufacturing processes and printing equipment and peripherals, manufacturing a printhead is still core of inkjet technology. In this study, a piezoelectric driven DOD (drop on demand) inkjet printhead has been fabricated on three layers of the silicon wafer in MEMS Technology because of its chemical resistance to industrial inks, strong mechanical properties and dimensional accuracy to meet the drop volume uniformity in printed electronics and display industries. The flow passage, filter and nozzles are precisely etched on the layers of the silicon wafers and assembled through silicon fusion bonding without additional adhesives. The piezoelectric is screen-printed on the top the pressure chamber and the nozzle plate surface is treated with non-wetting coating for jetting fluids. Printheads with nozzle number of 16 to 256 have been developed to get the drop volume range from 5 pL to 80 pL in various industrial applications. Currently our printheads are successfully utilized to fabricating color-filters and PI alignment layers in LCD Flat Panel Display and legend marking for PCB in Samsung Electronics.

• 한국정밀공학회지
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• 제28권10호
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• pp.1153-1158
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• 2011

Roll-to-roll process is an emerging mass production method for printed and flexible electronics such as touch screen panel, RFID tag, thin film solar cell, and flexible display due to its high throughput. High precision in printing and coating is required to apply functional materials onto substrate. For such reason, every part of the roll-to-roll equipment needs to be precisely fabricated and to retain its precision under regular operation. In this article, the precision of cantilever type idler roller and a novel method to mitigate its deflection under web tension loading are discussed and the method is verified using both the numerical and the experimental works. The proposed method improves the structural rigidity of cantilever type roller whose advantages, such as low capital cost and high web path configurability, are maintained.

• 한국전기전자재료학회논문지
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• 제23권6호
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• pp.477-480
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• 2010

In this study, we fabricate 3 wt% $Li_2CO_3$ doped $(Ba,Sr)TiO_3$ thick films on the Ag/Pd bottom electrode printed $Al_2O_3$ substrates for the LTCCs (low temperature co-fired ceramics) applications. From the X-ray diffraction analysis, 3 wt% $Li_2CO_3$ doped BST thick films on the Ag/Pd printed $Al_2O_3$ substrates, which sintered at $900^{\circ}C$, showed perovskite structure without any pyro phase. The dielectric properties of 3 wt% $Li_2CO_3$ doped BST thick films are measured from 1 kHz to 1 MHz. To investigate the electrical properties of 3 wt% $Li_2CO_3$ doped BST thick films, we employ the impedance spectroscopy. The complex impedance of 3 wt% $Li_2CO_3$ doped BST thick films are measured from 20 Hz to 1 MHz at the various temperatures.

• 복식문화연구
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• 제15권6호
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• pp.1053-1062
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• 2007

This study purposed to restructure representative traditional patterns formatively, manufacture actual cultural products with traditional dyeing technique using persimmon, and commercialize the results of the research. Traditionally in Korea, the dying of natural fiber such as cotton, flax and silk with persimmon was called Galmul dyeing, and clothes made through Galmul dyeing were called Galot. Galot was very useful because it is strong, does not pick up dirt easily, dries easily, and is cool in summer. In addition, cloth dyed with persimmon becomes stiff, so it does not need to be starched or ironed after washing. Moreover, it does not transmit heat under direct rays and is highly air-permeable, so it is cool and useful for standing the heat. In this study, we used traditional persimmon dyeing technique, printing traditional patterns fit for contemporary people's aesthetic sense not through dip-dying but through printing. When persimmon dyeing is used in expressing patterns, it produces not only visual effect but also embossing effect due to the characteristic of persimmon that makes printed patterns stiff, so we can obtain unique texture distinguished from other printing methods. We chose seven motive patterns, which were lotus pattern symbolizing eternal life, peony pattern symbolizing wealth and rank and prosperity, character Su(壽) pattern widely used as a symbol of health, bird and cloud pattern in the Goryeo Dynasty, Sahapyeoeuisohwa(四合如意小花) pattern printed on brocade in the Goryeo Dynasty, lattice pattern, cloth pattern on wall paintings from the Period of the Three Kingdoms. From each pattern chosen as a motive was extracted unit patterns and the original pattern was restored using Adobe Illustrator. Restored patterns were restructured to be applied to cultural products fit for contemporary formative sense. Fabrics used in dyeing were cotton, linen, ramie, silk, and polyester. Although the same persimmon dyeing was applied, we produced different feelings of patterns using various fabrics and in some cases gold and silver powder was added for the effect of gloss in addition to the embossing of patterns. Using printed fabrics we manufactured tea pads, place mats, cushions, wrapping cloth for gifts, wallet, lampshades.

• Bulletin of the Korean Chemical Society
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• 제35권10호
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• pp.3025-3029
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• 2014

To realize copper-based electrode materials for printed electronics applications, it is necessary to improve the adhesion strength between conductive lines and the substrate. Here, we report the preparation of Cu pastes using (3-glycidoxypropyl) trimethoxysilane (GPTMS) prepolymer as an adhesion promoter (AP). The Cu pastes were screen-printed on glass and polyimide (PI) substrates and sintered at high temperatures (> $250^{\circ}C$) under a formic acid/$N_2$ environment. According to the adhesion strengths and electrical conductivities of the sintered Cu films, the optimized Cu paste was composed of 1.0 wt % GPTMS prepolymer, 83.6 wt % Cu powder and 15.4 wt % vehicle. After sintering at $400^{\circ}C$ on a glass substrate and $275^{\circ}C$ on a PI substrate, the Cu films showed the sheet resistances of $10.0m{\Omega}/sq$. and $5.2m{\Omega}/sq$., respectively. Furthermore, the sintered Cu films exhibit excellent adhesion properties according to the results of the ASTM-D3359 standard test.

• 분석과학
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• 제20권5호
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• pp.393-399
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• 2007

본 연구에서는 갈락토오즈의 현장검사(point-of-care testing, POCT)를 위한 일회용 갈락토오즈 바이오센서 개발에 관해 논하고자 한다. Galactose oxidase(GAO)와 horseradish peroxidase(HRP) 두 효소를 0.05 M phosphate 완충용액에 용해시킨 후 스크린 프린팅(screen printing) 방법으로 제작한 전극위에 고정화하여 센서를 제작하였다. 이렇게 제작된 센서를 이용하여 $100{\mu}L$ 이하의 시료를 이용하여 갈락토오즈를 90초 이내에 측정하였다. 전극에서의 반응을 최적화하기 위하여 GAO 효소가 가장 우수한 활성을 나타내는 pH 7.0 완충용액을 이용하여 GAO와 HRP 효소를 1:1로 고정화하고, 1mM 1,1'-ferrocene-dimethanol 전자전달매개체를 도입하여 센서를 제작하였다. 유리 탄소전극의 경우 100 mV (vs Ag/AgCl), 스크린 프린트된 전극의 경우 -100 mV(vs Ag/AgCl)의 인가전압을 적용하였다. 본 연구에 의해 개발된 센서는 $0{\sim}400{\mu}M$의 갈락토오즈 농도에 대하여 우수한 직선성($r^2$ = 0.997, S/N = 3)을 나타내었고 낮은 인가전압을 적용하여 갈락토오즈를 측정하므로, ascorbic acid, uric acid 그리고 acetaminophen과 같은 방해물질의 영향을 최소화 할 수 있었다. 또한 갈락토오즈 표준 용액에 대하여 만족할 만한 재현성을 나타내었다(CV = 5%).