• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.8
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• pp.1115-1119
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• 2013

The carbon nanotube/poly-vinylidene fluoride (CNT/PVDF) composite films for the use of electronic devices were fabricated by spray coating method using the CNT/PVDF solution, which was prepared by adding PVDF pellets into the CNT dispersed N-Methyl-2-pyrroli-done (NMP) solution. The CNT/PVDF composite films were peeled off from the glass substrate and were investigated by the scanning electron microscopy, which revealed that the CNTs were uniformly dispersed in the PVDF films and thickness of the films were approximately $20{\mu}m$. The capacitance of the CNT/PVDF films increased dramatically by adding CNTs into the PVDF matrix, and finally saturated approximately 1880 pF. However, the I-V curves didn't show any saturation effect in the CNT concentration range of 0 ~ 0.04 wt%. Therefore we can control the performance of the devices from the CNT/PVDF composite film by adjusting the current level resulted from the CNT concentration with the uniform capacitance value.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.257-257
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• 2006

We chose three synthetic polymers, poly(propylene carbonate) (PPC), poly(vinylidene fluoride-co-hexafluoropropylene) (PVFHFP), and $Nafion^{(R)}$ that reveal different chemical and physical characteristics, and investigate their biocompatibilities to five different bacteria (that are most notorious for opportunistic and iatrogenic infections) and a human cell (HEp-2). The bacteria chosen in this study found to adhere onto the PPC and Nafion films but not to adhere on the PVFHFP film. On the other hand, both PVFHFP and Nafion films revealed good compatibility to HEp-2 and allowed the growth of the HEp-2 on the film surface but PPC showed poor compatibility to HEp-2. All results will be discussed with taking into account the surface characteristics of the polymers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.11
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• pp.716-719
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• 2016

In this paper, we fabricated flexible CNT/PVDF (carbon nanotube / polyvinylidene fluoride) piezoelectric composite device with flexible poly(3,4-ethylenedioxythiophene) : polystyrene sulfonate (PEDOT:PSS) conducting polymer electrode using spray coating method. We tried to improve the piezoelectric performance from the CNT/PVDF composite film by enhancing electrical conductivity of the PEDOT:PSS electrodes. Electrical conductivity of the PEDOT:PSS electrode was enhanced by dipping it into the EG (ethylene glycol) solvent. Changes of chemical composition of the PEDOT:PSS electrode were analyzed with the dipping time by XPS (x-ray photoelectron spectroscopy) in terms of oxygen (O1s). Finally, Piezoelectric performances such as output voltage and current were measured with the dipping time. We found that enhanced electrical conductivity of the PEDOT:PSS electrodes resulted in improvement of the piezoelectric performance of the CNT/PVDF films.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.36.2-36.2
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• 2010

A small amount of Na incorporated in $CuInSe_2$ (CIS) absorption layer has become widely accepted as a requirement for efficient polycrystalline CIS solar cells. However, there is ongoing argument on the role of sodium incorporated in the absorber. In this paper, CIS absorption layers have been deposited using the three-stage co-evaporation process on Mo coated non-Alkali glass substrates. The NaF was evaporated during the second-stage with various fluxes. This paper is focusing on differences of micro-structure and composition ratio of the absorber realized with different Na contents and the variation of electrical properties of the cells with the corresponding absorbers. The analytical results of x-ray diffraction (XRD) patterns, field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS) and current-voltage characteristics will be discussed to investigate the effect of NaF flux on the CIS absorber formation and its cell performance.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.8
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• pp.620-623
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• 2013

The carbon nanotube / poly-vinylidene fluoride (CNT/PVDF) composite films for the nano-generator devices were fabricated by spray coating method using the CNT/PVDF solution, which was prepared by adding PVDF pellets into the CNT dispersed N-Methyl-2-pyrroli-done (NMP) solution. The flexible CNT/PVDF composite films were investigated by the scanning electron microscopy, which revealed that the CNTs were uniformly dispersed in the PVDF matrix and thickness of the films was approximately $20{\mu}m$. Fourier transform infra-red spectra were used to investigate crystal structure of the as-spray-coated CNT/PVDF films, and we found that they revealed extremely large portion of the ${\beta}$ phase PVDF. The capacitance of the CNT/PVDF films increased by adding CNTs into the PVDF matrix, and finally saturated. However, the resistance didn't show any saturation effect in the CNT concentration range of 0~4 wt%. Finally, the resulting nano-generator devices revealed reasonable current output after given mechanical stress.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.512-513
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• 2007

Carbon/polymer based composite electrodes were fabricated by using Super p. Black(SPB) as a conductor and polyvinylidene fluoride (PVDF) as a binder. This type of composite electrode are considered as excellent candidates for heating film and variable resistor applications. Aim of this work is the study of the Mechanical and Electrical properties on composite electrode by the contents of SPB and MWCNT, respectively. The composite electrode having 10~15 wt% of SPB show good electrical and mechanical properties. Mechanical and electrical properties are increased by the addition of MWCNT into the composite electrode.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1156-1158
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• 1995

Charge decay, thermally stimulated current(TSC), charging and discharging currents(I) are measured for negatively corona-charged polymers. In this study, we will make an experiment in charge decay on polymer surface, TSC, polarity effect and the others in order to analysis it's mechanism. Especially polyvinylidene fluoride(PVDF) film is the best functional material which has been so far. Therefore, It's worthy of notice to investigate it's characteristic. And then some other functional polymers will be focused on. An experimental result was missed out for the shortage of setting. So, this thesis will be explained on the theory and direction of reseach hereafter.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.8 no.1
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• pp.76-82
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• 1999

Zinc phosphate cement has long been the material of choice for permanent luting of cast restorations, and through many years of use has been considered effective to retain castings. However, cast restorations cemented with this material have been susceptible to secondary caries. Glass ionomer luting agents become available in the late 1970s. These material s, through release of fluoride, show considerable promise as a means of reducing secondary caries. Other favorable traits include significantly less disintegration in vivo than zinc phosphate cements, a film thickness comparable to that of zinc phosphate cement, and adhesion to tooth structure. Compomer materials were created in 1993 as a filling material for deciduous teeth, cervical lesions, and class III cavities. In the meantime, compomer have been developed as chemical hardening cements for cast gold restorations. The aim of this paper is to review the articles on luting cements to help the choice of dental cements.

• Proceedings of the KAIS Fall Conference
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• 2010.11a
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• pp.451-453
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• 2010

PVDF(polyvinylidene fluoride) 필름은 압전특성을 가지며 음파에너지를 발생시키는 유연성 고분자필름이다. 이 연구에서는 기존 원통형 연직 배수재에 PVDF 필름의 음파에너지를 적용하여 점토의 미세입자가 배수재의 성능을 저하시키는 막힘현상(clogging)을 방지함으로써 배수재의 성능을 향상시키고, 압밀을 촉진시키고자 하였다.

• Proceedings of the KAIS Fall Conference
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• 2010.11a
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• pp.454-456
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• 2010

이 논문에서는 PVDF(polyvinylidene fluoride) 필름의 음파에너지를 이용하여 포화된 사질토에서의 탈수율을 증대하기 위한 방법을 연구하였다. 이 방법은 자연배수로 인한 이차적인 환경문제를 수반하는 강 또는 하천 등에 퇴적된 사질토의 탈수를 촉진시키기 위한 방법으로 PVDF필름의 음파에너지를 이용하였다. 이 연구에서는 PVDF필름의 주파수와 전압을 달리하여 사질토 지반에 적용되는 최적 주파수와 전압을 찾아내고 사질토에서 PVDF필름의 탈수능력을 알아보고자 하였다.