• 폴리머
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• 제26권4호
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• pp.543-550
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• 2002

곁사슬에 정공 및 전자 전달체로 triphenylamine moiety와 triazine moiety를 갖는 새로운 공중합체를 합성하였다. ITO/공중합체와 발광물질 (DCM, coumarin 6, DPvBi)/Al으로 구성되는 단층형 유기 EL 소자는 정공 전달 단위체와 전자 전달 단위체 비율이 6:4와 방광물질의 함유량이 30 wt%일 때 최고의 외부 양자 효율을 나타내었다. 특히 위에서 제작한 유기 EL 소자는 각각 발광물질에 상응하는 빨강 (620 nm), 초록 (520 nm)과 파랑색 (450 nm)의 빛을 발광하였다. 최고 휘도는 DC 12V에서 ITO/공중합체 (6:4)와 DCM (30 wt%)/Al으로 구성되는 소자를 구동하였을 때 500 cd/$m^2$이었다.

• 한국안광학회지
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• 제11권2호
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• pp.143-149
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• 2006

본 연구의 목적은 콘택트렌즈의 재료로 사용되는 실리콘 고분자를 합성하여 실리콘 재질의 가스 투과성 콘택트렌즈의 함수율과 광 투과성의 문제를 해결하는 데에 있다. 실험에 사용된 monomer들로는 NVP(N-vinly-pyrrolidone), MMA(methyl methacrylate), HEMA(Hydroxyethylmethacrylate)등과 교차결합제로 EGDMA(Ethylene Glycol Dimethacrylate)를 사용하였으며, 또한 콘택트렌즈 제조의 가장 좋은 조건을 위한 많은 조합 공식을 토대로 중합한 후, 중합된 개체를 가지고 함수율 측정과 광투과율 측정을 실시하였다. 본 실험의 연구 결과 재질의 투명성과 함수율을 동시에 추구하는 고분자를 합성하였고 그들의 물성을 측정하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.465-465
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• 2008

Conjugated polymers have attracted much scientific and technological research interest during the past few decades because of their potential use such as polymer light-emitting diodes (PLEDs).1,2 Particularly, lots of phenylene-based polymers such as polyfluorene and its derivatives have been synthesized because of their high photoluminescence quantum efficiencies and thermal stabilities. However, troublesome long wavelength emission in polymer film of polyfluorenes on heating during device formation or operation has been the crucial problem for practical applications. The source of the long wavelength emission was initially believed to be solely due to excimer emission as a result of polymer aggregation. It has also recently been correlated with emissions from ketonic defects in the fluorene units. Many efforts have been made to reduce the tendency to red-shifted emission. Here, we report for the first time the design and synthesis of novel 9,9-spiro bifluornene-based polymers containing heteroatoms such as N, S in its molecular skeleton. Especially, the 9,9-spiro bifluornene-based polymers containing N atom showed stable blue electroluminescence, which did not show spectral change upon thermal annealing.

• 한국전기전자재료학회논문지
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• 제16권9호
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• pp.826-832
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• 2003

Blending effects for generating a pretilt angle in nematic liquid crystal (NLC) with negative dielectric anisotropy on the blended polyimide (PI) of homeotropic and homogeneous alignment surface were studied. Also, we investigated the EO performances for the advanced VA- $\pi$ cell using this homeotropic blended PI surface. A many decrease of tilt angle on the polymer surface to blend homeotropic PI and homogeneous PI with side chain type was measured, and the tilt angle decreased as blended ratio and rubbing strength increase. However, a small decrease of tilt angle on the polymer surface to blend homeotropic PI and homogeneous PI with main chain type was measured. The blended effects for generating a pretilt angle were clearly observed, and the many decrease of tilt angle can be achieved by using the blended PI surface. The electro-optical (EO) characteristics using the advanced VA- $\pi$ cell using the homeotropic blended PI surface than that of conventional VA cell can be improved. We suggest that the developed advanced VA-$\pi$ cell on a homeotropic blended PI surface is a promising technique for the achievement of a fast response time, and a high contrast ratio.

• Macromolecular Research
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• 제14권3호
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• pp.331-337
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• 2006

In the present study we investigated the relationship between the morphology and mechanical properties of electrospun polysulfone (PSF)/polyurethane (PU) blend nonwovens, by using the electrospinning process to prepare three types of electrospun nonwovens: PSF, PU and PSF/PU blends. The viscosity, conductivity and surface tension of the polymer solutions, were measured by rheometer, electrical conductivity meter and tensiometer, respectively. The electrospun PSF/PU blend nonwovens were characterized by scanning electron microscopy (SEM) and with a universal testing machine. The SEM results revealed that the electrospun PSF nonwoven had a structure consisting of cross-bonding between fibers, whereas the electrospun PU nonwoven showed a typical, point-bonding structure. In the electrospun PSF/PU blend nonwovens, the exact nature of the point-bonding structure depended on the PU contents. The mechanical properties of the electrospun PSF/PU blend nonwoven were affected by the structure or the morphology. With increasing PU content, the mechanical behaviors, such as Young's modulus, yield stress, tensile strength and strain, of the electrospun PSF/PU blend nonwovens were by up to 80%.

• Journal of Electrical Engineering and Technology
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• 제7권6호
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• pp.932-939
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• 2012

This paper presents an equivalent circuit model of a LIPB (Li-Ion Polymer battery) for Hybrid Electric Vehicles (HEVs). The proposed equivalent circuit can be used to predict the charging/discharging characteristics in time domain as well as the impedance characteristic analysis in frequency domain. Based on these features, a one-cell model is established as a function of Depth of Discharge (DoD), and a 48-cell model for a battery pack was also established. It was confirmed by experiment that the proposed model predict the discharging and impedance (AC) characteristics quite accurately at different constant current levels. To check the usefulness of the proposed circuit, the model was used to simulate a motor driving circuit with an Insulated Gate Bipolar Transistor (IGBT) inverter and Brushless DC (BLDC) motor, and it is confirmed that the model can calculate the battery voltage fluctuation in time domain at different DoDs.

• 한국전기전자재료학회논문지
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• 제26권3호
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• pp.252-256
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• 2013

We introduced sensitizing dyes into the bulk-heterojunction (BHJ) photovoltaic (PV) layer of polymer solar cells (PSCs). The sensitizing dyes doped were Bis(tetra butyl ammonium) cis-dithio cyanato bis(2,2'-bipyridine-4-carboxylicacid-4'-carboxylate) ruthenium (II) (N719 dye) and the BHJ PV layer used was made of poly (3-hexylthiophene) (P3HT) and phenyl $C_{61}$-butyric acid methyl ester (PCBM). It was found that the N719 dyes increase the photovoltaic performance, i.e., increasing open-circuit voltage and short-circuit current density with improved fill factor. For the P3HT:PCBM PV cells doped with the N719 dyes (0.24 wt%), an increase in power conversion efficiency of 4.0% was achieved, compared to that of the control cells (3.6%) without the N719 dyes.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.332-335
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• 2000

We fabricated organic electroluminescent (EL) devices with single layer of poly(3-dodeoylthiophene) (P3DoDT) hlended with different amounts of poly(N-vinylcarbazole) (PVK) as a emitting layer. The molar ratio between P3DoDT and PVK changed with 1:0, 2:1 and 1:1. To improve the external quantum efficiency of EL devices, we applied insulating layer, LiF layer, between polymer emitting layer and Al electrode. All of the devices emit orange-red light and it's can be explained that the energy transfer occurs from PVK to P3DoDT. In the voltage-current and voltage-brightness characteristics of devices applied LiF layer, current and brightness increased with increasing applied voltage. The brightness of the device have a molar ratio 1:1 with LiF layer was about 10 times larger than that of the device without PVK at 6V. Electrical impedance properties of ITO/emitting layer/LiF/Al devices were investigated. In the Cole-Cole plots of impedance data, one semicircle was observed. Therefore, the equivalent circuit for the devices can be designed as a single parallel resistor and capacitor network with series resistor.

• 한국전기전자재료학회논문지
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• 제17권11호
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• pp.1192-1198
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• 2004

Hole transporting polymer(poly［N-(p-diphenylamine)phenylmethacrylamide］, PDPMA) was doped with nile red dye at various concentrations to study the influence of doping on the energy transfer during light emitting processes. Organic LEDs composed of ITO/blend(PDPMA -nile red)/ Alq$_3$/Al as well as thin films of blend(PDPMA -nile red)/ Alq$_3$ were manufactured for investigating photoluminescence, electroluminescence, and current-voltage characteristics. Atomic Force Microscopy was also used to observe surface morphology of the blend films. It was found that such doping. significantly influences the efficiency of the energy transfer from the Alq$_3$ layer to blended layer and the optical/electrical properties could be optimized by choosing the right concentration of the dye molecule. The results also showed a interesting correlation with the morphological aspect, i.e. the optimum luminescence at the concentration with the least surface roughness. When the concentration of nile red was 0.8 wt%, the maximum energy transfer could be achieved.

• 한국전기전자재료학회논문지
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• 제22권10호
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• pp.870-878
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• 2009

The large increase in the use of electricity has resulted in an ever-growing electric power demand. It has created the need for the construction of power transmission facility located close to the load centers and it also has to require wide right-of-way and large lots, that are not always available, for especially the installation of the towers. The difficulties in acquiring right-of-way have put pressure on energy companies to either upgrade a line on an existing right-of-way to higher voltage or build a new line on a narrow right-of-way. This paper presents the design of a compact tower with polymer Insulation arm, in order to reduce the separation between phases. the compact tower can be built on a narrow right-of-way. the compact tower can be designed based on 345 kV Tower regarding electrical clearances and right of way, therefore the conventional 154 kV Tower can be upgrading transmission line voltages have moved to 345 kV levels.