• 한국포장학회지
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• 제24권1호
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• pp.27-34
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• 2018

In this work, nano ZnO was introduced into low density poly ethylene (LDPE) composites films with various contents (0, 0.5, 1.0, 3.0 and 5.0 wt%) by melt-extrusion. Their basic properties such as crystallinity, chemical bonds and surface morphology were examined by XRD, FTIR and SEM. XRD patterns and FTIR peaks intensity were increased in proportion to the ZnO contents. SEM images showed well dispersed nano ZnO in LDPE composite films. Antimicrobial functionality of LDPE-nano ZnO composite films was also studied and the presence of nano ZnO resulted in significant improvement of antimicrobial functionality compared to the pure LDPE film. To evaluate influence of nano ZnO on LDPE properties required as packaging material, thermal, mechanical, gas barrier and optical properties of LDPE-nano ZnO composite films were characterized with various analytical techniques including TGA, UTM, OTR, WVTR and UV-Vis spectroscopy. As a result, except optical and mechanical properties of LDPE, no significant effects were found in other properties. Opacity of pure LDPE was greatly increased with increasing concentration of nano ZnO and tensile strength was also improved at 0.5wt% ZnO content.

• 한국염색가공학회지
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• 제30권3호
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• pp.190-198
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• 2018

We fabricated high transmission and high scattering poly(ethylene-co-vinyl acetate)(EVA) films embedding $SiO_2$ nanoparticles to improve outcoupling efficiency in organic display. The 800nm diameter $SiO_2$ nanoparticles aggregated and formed $1.56{\mu}m$ (with ${\pm}0.853{\mu}m$ standard deviation) diameter microparticles in EVA. The total transmission of scattering film was 83.3% on Polyethylene terephthalate(PET), which was higher than reference 82.8% PET substrate. The diffuse transmission and haze of the $SiO_2$ embedded EVA film were 76.1% and 91.4%, respectively. The optimized condition was 1:1 weight ratio of $SiO_2$ nanoparticles to EVA in Tetrahydrofuran(THF) solution. When the ratio of $SiO_2$ was larger than 1, the total transmission decreased by the increase in backscattering of light due to high scattering. With the optimized condition, we could succeed to fabricate a large scale film(35m in length) with a roll-to-roll process.

• Elastomers and Composites
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• 제46권4호
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• pp.290-294
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• 2011

전도성 고분자로 주목을 받고 있는 poly(3,4-ethylenedioxythiophene)- polystyrene sulfonate (PEDOT/PSS)는 분산 용매에 따라서 전기적 특성이 변화한다. 본 논문에서는 고형으로 최근 시판되고 있는 PEDOT/PSS를 물, 에탄올 (EtOH), 에틸렌 글리콜 (EG) 및 디메틸설폭사이드 (DMSO)에 분산시킨 용액을 PET 필름 상에 코팅하여 표면 저항을 측정한 결과, EG 및 DMSO를 사용하였을 경우에 약 100배 정도 더 낮은 표면 저항치를 나타내었다. 코팅된 필름의 열적 특성 및 화학적 특성을 TGA 및 XPS로 분석한 결과, 용매에 따른 차이는 발견되지 않았다. 그러나 분산액 자체의 입도를 분석한 결과, EG 및 DMSO 용액에서는 $1-3{\mu}m$ 정도의 입자로 존재하였으나, 물에서는 $0.1{\mu}m$ 이하의 미세 입자로 존재하는 것을 확인할 수 있었다. 전기적 특성의 차이는 분산 상태에서의 PEDOT/PSS 입자 크기에 영향을 받는 것으로 판단된다.

• 한국재료학회지
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• 제25권12호
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• pp.719-726
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• 2015

For a decade, solution-processed functional materials and various printing technologies have attracted increasingly the significant interest in realizing low-cost flexible electronics. In this study, Cu nanoparticles are synthesized via the chemical reduction of Cu ions under inert atmosphere. To prevent interparticle agglomeration and surface oxidation, oleic acid is incorporated as a surface capping molecule and hydrazine is used as a reducing agent. To endow water-compatibility, the surface of synthesized Cu nanoparticles is modified by a mixture of carboxyl-terminated anionic polyelectrolyte and polyoxylethylene oleylamine ether. For reducing the surface tension and the evaporation rate of aqueous Cu nanoparticle inks, the solvent composition of Cu nanoparticle ink is designed as DI water:2-methoxy ethanol:glycerol:ethylene glycol = 50:20:5:25 wt%. The effects of poly(styrene-co-maleic acid) as an adhesion promoter(AP) on rheology of aqueous Cu nanoparticle inks and adhesion of Cu pattern printed on polyimid films are investigated. The 40 wt% aqueous Cu nanoparticle inks with 0.5 wt% of Poly(styrene-co-maleic acid) show the "Newtonian flow" and has a low viscosity under $10mPa{\cdots}S$, which is applicable to inkjet printing. The Cu patterns with a linewidth of $50{\sim}60{\mu}m$ are successfully fabricated. With the addition of Poly(styrene-co-maleic acid), the adhesion of printed Cu patterns on polyimid films is superior to those of patterns prepared from Poly(styrene-co-maleic acid)-free inks. The resistivities of Cu films are measured to be $10{\sim}15{\mu}{\Omega}{\cdot}cm$ at annealing temperature of $300^{\circ}C$.

• 한국토양비료학회지
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• 제18권2호
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• pp.140-147
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• 1985

연초재배방법(煙草栽培方法)을 피복(被覆)과 무피복(無被覆)으로 하여 작토층(作土層)의 환경변화(環境變化)(1보(報))에 따른 시비(施肥)된 비료(肥料)의 무기화작용(無機化作用)과 무기화(無機化)된 양분(養分)들의 동태(動態)에 관(關)하여 조사(調査)한 결과(結果)는 다음과 같다. 1. 피복(被覆)에 의한 작토층(作土層)의 수분보존효과(水分保存效果)와 지온상승효과(地溫上昇效果)로 인(因)하여 질소(窒素)의 무기화작용(無機化作用) (암모니아화작용, 질산화성작용)은 피복조건(被覆條件)에서 더 빠르게 촉진(促進)되어 생육초기(生育初期)에 질산태질소(窒酸態窒素)의 공급(供給)을 증대(增大)시켰으나 무피복조건(無被覆條件)에서는 질소(窒素)의 무기화(無機化) 작용(作用)이 지연되어 생육후기(生育後期)까지 작토층(作土層)의 질산태질소 함량이 높게 유지되었다. 2. 작토층(作土層)의 유효인산함량(有效燐酸含量)은 피복조건(被覆條件)에 관계없이 시비층(施肥層)에서 가장 많은 함량(含量)을 나타냈으며, 연초(煙草)의 재배유무(栽培有無)에 따라서도 차이(差異)없이 일정(一定)한 경향을 보이지 않았다. 3. 시비(施肥)된 칼륨은 피복조건(被覆條件)에 차이(差異)없이 생육후기(生育後期)까지 잔류(殘留)되는 량이 많았다. 4. 피복조건(被覆條件)에서 무기화(無機化)된 양분(養分)들 ($NH_4-N$, $NO_3-N$, K)은 재배기간(栽培其間)이 경과함에 따라 시비층(施肥層)에서 이랑상층부(上層部)로 이동집적(移動集積)되었으나 무피복조건(無被覆條件)에서는 하층부(下層部)에 더 많이 분포(分布)되며 특(特)히 질산태질소(窒酸態窒素)는 용탈유실되는 정도가 현저하였다. 작토층위간((作土層位間) 유효양분(有效養分)들의 이동성(移動性)은 $NO_3-N$ $$\geq_-$$ $NH_4-N$ > K > Available $P_2O_5$의 순(順)이었다. 5. 피복조건(被覆條件)에서 작토층(作土層)의 유효양분(有效養分)들 ($NH_4-N$, $NO_3-N$, K)은 183mm의 집중강우(集中降雨)에서도 용탈유실되지 않았으며 수확종료후(收穫終了後)까지 이랑토층부(土層部)와 시비층(施肥層)에 잔류집적(殘留集積)되는 량이 현저하게 많았다.

• 한국포장학회지
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• 제20권3호
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• pp.77-84
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• 2014

PLA와 nanoclay인 Nanomer$^{(R)}$ I.44P를 이용한 환경 친화적인 nanocomposites을 개발하였다. PLA/Nanomer$^{(R)}$ I.44P nanocomposites의 상온 건조 후 잔존하는 용매를 제거하기 위해 진공건조를 하였으며, 진공건조 시간이 8시간 까지는 신장율이 크게 감소하였으며, 그 이후에는 유의적인 차이가 없었다. Nanoclay가 PLA matrix내에서 균일하게 분산시키기 위해 초음파 처리를 하였으며, 초음파 처리시간이 5분까지는 인장강도 및 영모듈러스가 증가하는 경향을 보였으나 5분 이상의 초음파 처리에서는 시간이 증가함에 따라 인장 특성도 점차 감소하였고, 특히 15분 이상 초음파 처리를 하였을 때에는 nanoclay가 뭉치는 현상이 관찰 되었다. Nanoclay의 양이 증가할수록 nanocomposites의 가시광선 영역에서의 투과성(trasmittance)은 62.5%에서 7.8%로 크게 감소하였다. Water vapor permeability (WVP)는 nanoclay의 첨가량에 따라 감소하는 경향을 보이며, 5%의 nanoclay 첨가 시 $3.5{\times}10^{-11}g{\cdot}m/m^2{\cdot}s{\cdot}Pa$로 control에 비해 약 43%가 감소하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.17-17
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• 2009

Single-walled carbon nanotubes (SWCNTs) have attracted much attention as promising materials for transparent conducting films (TCFs), thanks to their superior electrical conductivity, high mechanical strength, and complete flexibility. The CNT-based TCFs can be used in a variety of application fields as flexible, transparent electrodes, including touch panel screens, flexible electronics, transparent heaters, etc. First of all, this study investigated the effect of a variety of surfactants on the dispersion of SWCNTs in an aqueous solution. Following the optimization of the dispersion by surfactants, flexible TCFs were fabricated by spraying the CNT suspension onto poly(ethylene terephthalate) (PET) substrates. The sheet resistances of the TCFs having different surfactants were investigated with treatment in nitric acid ($HNO_3$) whose concentration and period of treatment time were varied. It seems that the $HNO_3$ removes the surfactants from and is simultaneously doped into the SWCNT network, reducing the contact resistance between CNTs. TCFs were characterized by UV-VIS spectroscopy, thermogravimetric analyzer (TGA), scanning electron microscopy (SEM), and four-point probe.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.89-92
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• 2001

Drop weight impact tests were performed to investigate the impact behavior of carbon fiber/epoxy composite laminates reinforced by short fibers and other interleaving materials. Characterization techniques, such as cross-sectional fractography and scanning acoustic microscopy, were employed quantitatively to assess the internal damage of some composite laminates. Scanning electron microscopy was used to observe impact damage and fracture modes on specimen fracture surfaces. The results show that composite laminates experience various types of fracture; delamination, intra-ply cracking, matrix cracking and fiber breakage depending on the interlayer materials. Among the composite laminates tested in this study, the composites reinforced by Zylon fibers showed very good impact damage resistance with medium level of damage, while the composites interleaved by poly(ethylene-co-acrylic acid) (PEEA) film is expected to deteriorate the bulk strength due to the reduction of fiber volume fraction, even though the damaged area is significantly reduced.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.254-254
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• 2009

Single-walled carbon nanotubes (SWCNTs) have attracted much attention as promising materials for transparent conducting films (TCFs), thanks to their superior electrical conductivity, high mechanical strength, and complete flexibility. The CNT-based TCFs can be used in a variety of application fields as flexible, transparent electrodes, including touch panel screens, flexible electronics, transparent heaters, etc. First of all, this study investigated the effect of a variety of surfactants on the dispersion of SWCNTs in an aqueous solution. Following the optimization of the dispersion by surfactants, flexible TCFs were fabricated by spraying the CNT suspension onto poly(ethylene terephthalate) (PET) substrates. The sheet resistances of the TCFs having different surfactants were investigated with treatment in nitric acid ($HNO_3$) whose concentration and period of treatment time were varied. It seems that the $HNO_3$ removes the surfactants from and is simultaneously doped into the SWCNT network, reducing the contact resistance between CNTs. TCFs were characterized by UV-VIS spectroscopy, thermogravimetric analyzer (TGA), scanning electron microscopy (SEM), and four-point probe.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1908-1910
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• 2001

본 논문은 마이크로머시닝 기술을 이용하여 lift-off 공정으로 패턴닝 한 후 TMAH (Tetramethylammonium Hydroxide) 용액으로 $5{\sim}100{\mu}m$ 두께의 실리콘 다이어프램을 제작하였다. Pt/Ti 박막을 HF 전해질의 mask 물질로 사용하여 HF 용액 내에서 전기화학적 방법으로 정전압을 인가, 다이어프램 영역에 다공질 실리콘을 성장시켜 관통하였다. 140$^{\circ}C$의 질소 분위기에서 $10{\sim}15{\mu}m$두께의 LDPE(Low Density Poly Ethylene) 필름을 물리적으로 다이어프램 영역에 코팅하고 $K_2CO_3$ 용액내에서 ${CO_3}^{2-}$ 이온의 barrier에 의한 전류의 감소를 전기화학적인 분석방법에 의하여 측정하였다. 일정 전압하에서 이온 농도에 기인하는 다공질 실리콘과 LDPE 표면에서 Barrier의 두께에 따른 저항의 증가를 전극으로 감지하여 농도-전류의 특성을 측정하고 이것을 기준으로 하여 미지농도의 $K_2CO_3$ 용액내의 ${CO_3}^{2-}$ 이온 농도를 측정하였다.