• 한국재료학회지
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• 제22권9호
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• pp.476-481
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• 2012

Among the various roll-to-roll printing technologies such as gravure, gravure-offset, and reverse offset printing, reverse offset printing has the advantage of fine patterning, with less than 5 ${\mu}m$ line width. However, it involves complex processes, consisting of 1) the coating process, 2) the off process, 3) the patterning process, and 4) the set process of the ink. Each process demands various ink properties, including viscosity, surface tension, stickiness, and adhesion with substrate or clich$\acute{e}$; these properties are critical factors for the printing quality of fine patterning. In this study, Ag nano ink was developed for reverse offset printing and the effect of polyvinylpyrrolidone(PVP), used as a capping agent of Ag nano particles, on the printing quality was investigated. Ag nano particles with a diameter of ~60 nm were synthesized using the conventional polyol synthesis process. Ethanol and ethylene glycol monopropyl ether(EGPE) were used together as the main solvent in order to control the drying and absorption of the solvents during the printing process. The rheological behavior, especially ink adhesion and stickiness, was controlled with washing processes that have an effect on the offset process and that played a critical role in the fine patterning. The electrical and thermal behaviors were analyzed according to the content of PVP in the Ag ink. Finally, an Ag mesh pattern with a line width of 10 ${\mu}m$ was printed using reverse offset printing; this printing showed an electrical resistivity of 36 ${\mu}{\Omega}{\cdot}cm$ after sintering at $200^{\circ}C$.

• BMB Reports
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• 제42권2호
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• pp.106-112
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• 2009

The bio-complex "reaction pattern in vertebrate cells"(RiV) is mainly represented by characteristic exosome-like particles - probably as reaction products of cells to specific stress. The transcription factor NF-kappaB plays a central role in inflammation. We tested the hypothesis that RiV particle preparations (RiV-PP) reduce cellular adhesion molecule (CAM) expression (ICAM-1, VCAM-1, E-selectin) by the attenuation of NF-kappaB translocation in human umbilical vein endothelial cells (HUVEC). After 4 hours, pre-incubation of HUVEC with RiV-PP before stimulation with TNF-alpha significantly reduced ICAM-1 (65.5${\pm}$10.3%) and VCAM-1 (71.1${\pm}$12.3%) mRNA expression compared to TNF-alpha-treated cells (100%, n=7). ICAM-1 surface expression was significantly albeit marginally reduced in RiV/TNF-alpha- treated cells (92.0${\pm}$5.6%, n=4). No significant effect was observed on VCAM-1 surface expression. In RiV/TNF-alpha-treated cells (n=4), NF-kappaB subunits p50 (85.7${\pm}$4.1%) and p65 (85.0${\pm}$1.8%) nuclear translocation was significantly reduced. RiV-PP may exert an anti-inflammatory effect in HUVEC by reducing CAM mRNA expression via attenuation of p50 and p65 translocation.

• 한국자기학회지
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• 제11권6호
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• pp.239-244
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• 2001

최근 연구가 활발히 진행되고 있는 RF 대역에서 사용가능한 인덕터를 제조하여 특성을 평가하였다. 인덕턴스와 Q값을 높이기 위하여 5000 두께의 F $e_{78.81}$T $a_{8.47}$ $N_{12.71}$ 연자성박막을 삽입하였으며, 자성박막의 FMR 공진주파수를 인위적으로 확장시키기 위하여 pattern을 형성시켜 shape anisotropy를 증가시켰다. 또한 코일부분은 lift-off process를 이용하여 제조하였다. 제조된 인덕터의 디자인은 4턴의 rectangular spiral형태였으며, 측정된 특성은 Ti/Ag air-core의 경우 5 GHz까가지 공진이 없었으며 2GHz에서 Q값이 9, 인덕턴스 8.4nH였다. 자성박막을 이용한 경우 9 nH에 공진주파수는 약 700 MHz부근이었다.다.

• 한국정밀공학회지
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• 제30권6호
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• pp.578-583
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• 2013

The lighting devices using organic light emitting diodes (OLEDs) are actively researched because of the various advantages such as high power efficiency and 2-dimensitonal lighting emitting. To commercialize those OLED lighting devices, the manufacturing cost must be downed to comparable price with conventional light sources. Here, we demonstrate a reverse gravure-offset or gravure off-set printed metal electrode for the auxiliary electrode for OLED lighting devices. For the fabricated OLED's auxiliary electrode, we used Ag nano-paste and printed metal grid structure with a line width and spacing of several ten and hundred micrometer by using gravure-offset printing. In the end the printing metal grid pattern are successfully achieved by optimization of various experimental conditions such as printing pressure, printing speed and printing delay time.

• 한국재료학회지
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• 제24권11호
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• pp.632-638
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• 2014

We investigated the effects of DMAB (Borane dimethylamine complex, C2H10BN) in electroless Ni-B film with addition of DMAB as reducing agent for electroless Ni plating. The electroless Ni-B films were formed by electroless plating of near neutral pH (pH 6.5 and pH 7) at $50^{\circ}C$. The electroless plated Ni-B films were coated on screen printed Ag pattern/PET (polyethylene terephthalate). According to the increase of DMAB (from 0 to 1 mole), the deposition rate and the grain size of electroless Ni-B film increased and the boron (B) content also increased. In crystallinity of electroless Ni-B films, an amorphization reaction was enhanced in the formation of Ni-B film with an increasing content of DMAB; the Ni-B film with < 1 B at.% had a weak fcc structure with a nano crystalline size, and the Ni-B films with > 5 B at.% had an amorphous structure. In addition, the Ni-B film was selectively grown on the printed Ag paste layer without damage to the PET surface. From this result, we concluded that formation of electroless Ni-B film is possible by a neutral process (~green process) at a low temperature of $50^{\circ}C$.

• 대한의용생체공학회:의공학회지
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• 제36권5호
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• pp.221-227
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• 2015

In this study, Multi-Array Electrodes (MAE) and Programmable Multi-channel Electrical Stimulator (PMES) were implemented for firing Trigger Points (TPs) of the patient with Myofascial Pain Syndrome (MPS). MAE has 25 Ag/AgCl electrodes arranged in the form of array ($5{\times}5$) fabricated with flexible pad, which are applicable to be easy-attached to curved specific region of the human body. PMES consisted of 25 channels. Each channel was to generate various electric stimulus patterns (ESPs) by changing the mono-phasic or bi-phasic of ESP, On/Off duration of ESP, the interval between ESP, and amplitude of ESP. PMES hardware was composed of Host PC, Stimulation Pattern Editing Program (SPEP), and Multi-channel Electrical Stimulator (MES). Experiments were performed using MAE and PMES as the following. First experiment was performed to evaluate the function for each channel of Sub- Micro Controller Unit (SMCU) in MES. Second experiment was conducted on whether ESP applied from each channel of SMCU in PMES was focused to the electrode set to the ground, after applying ESP being output from each channel of SMCU in PMES to MAE.

• Transactions on Electrical and Electronic Materials
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• 제4권4호
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• pp.22-25
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• 2003

High series resistance due to the presence of glass frit is one of the major problems for screen printed silicon solar cells. Cells having electrical parameters below the prescribed values are usually rejected during solar module fabrication. Therefore, it is highly desirable to improve the electrical parameters of the silicon solar cells and thereby to increase the overall production yield. It was observed that, the performance of low quality mono-crystalline silicon solar cells made by standard screen printing technology could be improved remarkably by novel surface treatment. We have chemically treated the surface using sodium hydroxide (NaOH) and silver nitrate ($AgNO_3$) solutions. NaOH treatment helps to reduce the series resistance by decreasing the presence of excess glass frit on the top silver grid contact. The $AgNO_3$ treatment is used to reduce the series resistance comes from the deposition of silver on the grids by filling the holes present (if any) within the grid pattern.

• Corrosion Science and Technology
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• 제6권6호
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• pp.304-307
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• 2007

As to the reflection electrode of LCD (liquid crystal displays), silver-copper-gold alloy (hereafter, it is called as ACA (Ag98%, Cu1%, Au1%)) is an effective material of which weathering resistance can be improved more compared with pure silver. However, there is a problem that gold remains on the substrate as residues when ACA is etched in cerium ammonium nitrate solution or phosphoric acid. Gold can not be etched in these etchants as readily as the other two alloying elements. Gold residue has actually been removed physically by brushing etc. This procedure causes damage to the display elements. Another etchant of iodine/potassium iodide generally known as one of the gold etchants can not give precise etch pattern because of remarkable difference in etching rates among silver, copper and gold. The purpose of this research is to obtain a practical etchant for ACA alloy. The results are as follows. The cyanogen complex salt of gold generates when cyanide is used as the etchant, in which gold dissolves considerably. Oxygen reduction is important as the cathodic reaction in the dissolution of gold. A new etchant of sodium cyanide / potassium ferricyanide whose cathodic reduction is stronger than oxygen, can give precise etch patterns in ACA alloy swiftly at room temperature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.53-53
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• 2010

The development of synthetic pathway to produce a highly yield nanoparticles is an important aspect of industrial technology. Herein, we report a simple, rapid approach to synthesize organic-soluble Cu and Ag nanoparticles in colloidal method for the application in a conductive pattern using inkjet printing. The silver nanoparticles have been synthesized in highly concentrated organic phase. The Cu nanoparticles have been synthesized by the reducing of the copper oxide materials using acid molecules in high concentrated organic phase. Their sintering and electric conductivity properties were investigated by melting process between $200^{\circ}C$ and $250^{\circ}C$ for application to printed electronics.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.466.1-466.1
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• 2014

$TiO_2$는 저렴한 가격, 적절한 bandgap, 열적, 화학적, 생물학적 안정성 등으로 촉망받는 광촉매 물질이다. $TiO_2$는 rutile (tetragonal, space group: P42/mnm), anatse (tetragonal, space group: I41/amd), and brookite (orthorhombic, space group: Pbca )의 3가지 대표적인 결정구조를 가지고 있다. Rutile과 anatase는 1972년 Fujishima와 Honda가 $TiO_2$의 광촉매 특성을 발견 한 후로 아주 많은 연구가 되어왔다. 반면 brookite의 경우는 자연에 거의 존재하지 않으며, 합성방법도 어려워서 rutile과 anatase에 비해 많은 연구가 되지 않았다. 본 연구에서는 brookite를 포함한 다양한 $TiO_2$ 나노구조를 간단한 수열합성법으로 티타늄 호일 위에 합성하였다. 합성된 $TiO_2$는 반응 온도와 시간, additive의 농도에 따라서 sheet, tube, wire, pyramidal 의 4가지 morphologies를 가졌다. 이 다양한 morphologies은 SEM과 TEM으로 분석되었으며, 각 물질의 결정 구조는 XRD분석과 TEM의 SAED pattern 분석으로 sheet, tube, wire은 anatase, pyramidal 구조는 brookite라는 것이 확인 되었다. 위의 방법으로 합성된 각각의 $TiO_2$ 물질들을 working 전극으로, Pt와 Ag/AgCl을 reference와 counter 전극으로 만들어서 photoelectrochemical 특성을 측정해서 비교를 해보았을 때, brookite 물질이 anatase보다 더 좋은 photoelectrochemical 특성을 나타내는 것을 확인하였다.