• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.399-400
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• 2010

This paper presents results of an experimental program for evaluating the mechanical properties of green strain-hardening cementitious composite (SHCC) using recycled material. Recycled poly ethylene terephthalate (PET) fiber, fly ash, and recycled sand from waste concrete are used as materials for green SHCC. Test results indicated that average tensile strength of five dumbbell-shaped specimen is 4.76MPa and average compressive and flexural strength of three specimens are 38MPa and 7.40MPa, respectively.

• The International Journal of Costume Culture
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• v.6 no.2
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• pp.134-146
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• 2003

Polyester of linear homopolymer poly(ethylene terephthalate)(PET) was chemically modified through the formation of branched copolymer to improve the undesirable properties of fiber. Photo-induced graft copolymerization of the acrylic monomers acrylic acid (AA) and methyl acrylate (MA) in the liquid and vapor phase, respectively, onto N,N-dimetylformamide (DMF)-pretreated PET fibers was carried out. The effect of various synthesis conditions and DMF pretreatment of the PET on the graft yield was investigated. Grafting mechanism was analysed. The grafting was promoted by increasing DMF pretreatment temperature and amount of DMF retention in the fiber. The increasing biacetyl and monomer flow time, and irradiation time enhanced the grafting up to a certain amount and thereafter it decreased.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.248-251
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• 1999

The optimal reaction conditions are determined for a PET process, which consists of transesteriflcation, prepolymerization and polycondensation reactors in series. Based on the simulation results of the reactor system, we scrutinize the cause and effect between the reaction conditions and the final properties of the polymer product. We then select the process variables with significant influence on the properties of polymer as control variables and calculate the optimal reaction conditions by iterative dynamic programming (IDP) algorithm with constraints. A new reaction scheme incorporating reactions for by-products as well as three main reactions is considered in the constrained IDP method.

• Textile Coloration and Finishing
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• v.7 no.1
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• pp.1-9
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• 1995

In order to improve dyeability of poly(ethylene terephthalate)(PET) micro filament fabrics, the effect of the prior oxygen low temperature plasma on the subsequent dyeing(deep dyeing, printing) was examined in various conditions. The apparent concentration of dyed PET micro filament fabrics was increased by $O_{2}$plasma treatment. Higher discharge power levels and higher reactor pressure values created more significant effect. The wettability was significantly increased by $O_{2}$ plasma treatment. Therefore, it is predicted that introducing hydrophilic group on the surface of material can improve the apparent concentration of PET micro filament fabrics.

• Korea-Australia Rheology Journal
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• v.21 no.3
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• pp.149-153
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• 2009

Profile development of the melt spinning process of poly(ethylene terephthalate) (PET) was simulated by a numerical method under the consideration of two constitutive equations of Newtonian and upper convected Maxwell (UCM) models. The viscoelastic characteristics of the polymer were considered via UCM constitutive equation that considered relaxation time as a function of temperature and molecular weight. The UCM model predicted the diameter profile better than the Newtonian, while velocity development was slower than the Newtonian model. Viscoelasticity played an important role in accurately predicting diameter profile. However, even though neck-like deformation was observed in the UCM model, the exact position of the deformation under high speed spinning was not obtained.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.203-203
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• 2012

The SWCNTs network are formed on various plastic substrates such as poly(ethylene terephthalate) (PET), polyimide (PI) and soda lime glass using roll-to-roll printing and spray process. Selective patterning of carbon nanotubes film on transparent substrates was performed using a femtosecond laser. This process has many advantages because it is performed without chemicals and is easily applied to large-area patterning. It could also control the transparency and conductivity of CNT film by selective removal of CNTs. Furthermore, selective cutting of carbon nanotube using a femtosecond laser does not cause any phase change in the CNTs, as usually shown in focused ion beam irradiation of the CNTs. The patterned SWCNT films on transparent substrate can be used electrode layer for touch panels of flexible or flat panel display instead indium tin oxide (ITO) film.

• Textile Coloration and Finishing
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• v.9 no.2
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• pp.50-56
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• 1997

Poly(ethylene terephthalate) (PET) has been etched by sputtering in the presence of argon gas and the resulting surface modifications investigated via weight loss, time of water permeation, half value period, scanning electron microscope(SEM) and color difference measurements. According to increasing sputter etching time, weight loss increased, the time of water permeation and half value period of the sputter etched PET fabrics decreased. Color depth of fabrics increased by increasing sputter etching time. We investigated the fabric surface modification by SEM. Many microcraters on the fabric surface formed by the sputter etching resulted in increase of surface area of the fabric and wettability.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.127-128
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• 2014

현재 기술 산업에서 PET위 무전해 도금을 실행하기 위해 다양한 전처리 공정과 Catalyst가 소개되고 있다. 그 중에서 가장 일반적으로 사용되고 있는 Catalyst는 Palladium으로서 Tin과 산화 환원 반응으로 Electroless Copper Deposition 단계에서 구리 도금의 Target으로 작용하고 있다. 하지만 상대적으로 Palladium은 생산 비용이 높으며 Tin은 쉽게 산화되는 문제점이 남아 있다. 이를 대체하기 위한 대안 공정으로서 Palladium 대신 Silver를 이용하여 Catalyst로서의 역할을 하는 공정이다. 이전에 PET위 전처리 공정으로 Ultra Violet을 사용하여 표면을 개질 시키는 방법을 연구했으며, 그 후 Potassium Permanganate와 Silver Catalyst의 Mechanism을 연구 했다. PET 표면 개질을 거치면서 화학 구조가 바뀌어 표면에 Carbon Carbon Double Bond를 형성한다. 이때 Permanganate ion이 새로이 형성된 이중 결합과 반응하여 두 개의 extra-OH functional group을 생성함과 동시에 $MnO_2$를 만들어 표면에 흡착 시킨다. $MnO_2$는 전위차에 의해 Silver Ion과 Redox Reaction을 일으키며 실질적인 Catalyst 역할을 하게 된다. Silver Catalyst는 무전해 구리 도금 용액 안에서 Copper의 Target으로 작용한다.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.275-276
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• 2003

Electrostatic spinning or electrospinning has been recently paid attention to prepare ultrafine fiber mats which are composed of diameters in a range of submicrons to nanoscale size[l]. Due to small diameters and porous structure, electrosun fibers have a high specific surface area and expected to use for broad applications, such as filters, membranes, wound dressing materials, artificial blood vessels. a nonwoven fabric, a reiforcement of nanocomposites[2,3], etc. (omitted)

• Journal of the Korean Ceramic Society
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• v.55 no.4
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• pp.325-336
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• 2018

Perovskite solar cells (PSCs) are a new class of photovoltaic devices, which have attracted significant attention due to their remarkable optoelectrical properties, including high absorption coefficients, high carrier mobilities, long carrier diffusion lengths, tunable bandgaps, low cost, and facile fabrication. PSCs have reached efficiencies of 22.70% and 18.36% on rigid fluorine-doped tin oxide and poly(ethylene terephthalate) substrates, respectively; these are comparable to those of single-crystal silicon and copper-indium-gallium-selenium solar cells. Over the past eight years, the photo conversion efficiency of PSCs has been significantly improved by device-architecture adjustments, and absorber and electron/hole transport layer optimization. Each layer is important for the performance of PSCs; hence, we discuss achievements in flexible perovskite solar cells (FPSCs), covering electron/hole-transport materials, electrode materials. We give a comprehensive overview of FPSCs and put forward suggestions for their further development.