• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.402-405
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• 2002

본 연구에서는 22.9KV 중전압 삼상 배전선로에 9KHz-30MHz의 주파수를 반송파신호로 인가하였을 때 나타나는 방사전계를 측정하였다. 중 전압 통신채널을 대지귀로방식으로 디지털신호를 인가하였을 때 3m와 10m법의 표준 방사전계 측정법을 적용하였다. 삼삼 배전선로에서 단일신호 보다 다중 신호전송에서 방사전력이 우수함이 나타내었으며 다중전송신호의 세기를 20㏈m로 하였을 때 1.8km까지 전송가능함을 확인하였고, 반송주파수 30MHz에 대하여 10m 측정법으로 방사전계를 측정하였더니 40㏈u/m임을 확인하였다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1448-1449
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• 2008

Inkjet printing is commonly used in depositing the solution of functional materials on the specific locations of a substrate, and also it can provide easy and fast patterning of polymer films over a large area. Inkjet printing is applicable to fabricating an organic light emitting diode (OLED), since conducting materials used as emissive electroluminescent layers can be manufactured into inks for ink jetting. By using the inkjet technology, we have succeeded in patterning a poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) layer and a poly[2-Methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) layer on the Indume tin oxide (ITO) patterned substrates, and fabricating organic light emitting diodes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.370-373
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• 2001

Temperature-dependent current-voltage characteristics of Organic Light-Emitting Diodes(OLEDs) were studied. The OLEDs were based on the molecular compounds, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine (TPD) as a hole transport and tris(8-hydroxyquinoline) aluminum($Alq_3$) as an electron transport and emissive material. The current-voltage characteristics were measured in the temperature range of 10[K] and 300[K]. A conduction mechanism in OLEDs was interpreted in terms of tunneling and trap-filled limited current.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.137-140
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• 2001

To improve structural properties and induce higher conductivity, we have annealed emitting layer. The temperature condition was investigated by various experiment. To observe the surface morphology of emitting layer, measured the AFM and the X -ray diffraction pattern of P3HT film is shown. It is move to slightly low angles and diffraction peaks also become much sharper. After annealing of emitting layer, EL intensity and Voltage-current-luminance curve is better as compared with untreated. But PL intensity was decreased. It is known that by emission principal. After annealing of emitting layer, EL devices enhances the interface adhesion between the emissive polymer and Indium-tin-oxide electrode, which takes a critical role to improve the emitting properties of EL devices.

• Journal of Surface Science and Engineering
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• v.29 no.6
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• pp.648-653
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• 1996

Hydrogenated amorphous carbon(a-C:H) films are prepared by rf plasma CVD in a $CH_4$ source gas system diluted with Ar of $H_2$. The spectra of emissive and reactive species in the plasma are detected using in stiu optical emission spectroscopy. Inaddition, the relationship between the film properties which can be varied by the deposition parameters and the Raman spectra is studied. In the $CH_4/H_2$ gas system, the emission intensities of CH and $H \tau$ decrease and those of $H \alpha$, $H \beta$, $C_2$ and Ar increase with increasing $H_2$ concentration, The formation of $C_2$ and CH in the $CH_4/Ar/H_2$ gas system is greatly suppressed by hydrogen addition and the excess of hydrogen addition is found to form graphite structure. The $C_2$ formation in the gas phase enhances a-C:H film formation.

• Communications for Statistical Applications and Methods
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• v.8 no.1
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• pp.299-309
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• 2001

In PET(Positron Emission Tomography), it is necessary to use transmission scan data in order to estimate the attenuation map. Recently, there are several empirical studies in which one might be able to estimate attenuation map and activity distribution simultaneously with emissive sinogram alone without transmission scan. However, their algorithms are based on the model in which does not include the background counts term, and so is unrealistic. If the background counts component has been included in the model, their algorithm would introduce non-monotonic reconstruction algorithm which results in vain in practice. in this paper, we develop a monotonic and parallelizable algorithm for simultaneous reconstruction of both characteristics and present the validity through some simulations.

• Journal of Information Display
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• v.11 no.2
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• pp.39-44
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• 2010

The time dependences of the luminance properties of 55-inch CCFL and LED backlights and 32-inch FFL backlights with LCD panels were investigated during the warm-up time from the cold start. The long-term luminance maintenance curve of a standard CCFL was examined in a time window up to 5000 hours. These two time dependences are important characteristics from the viewpoint of initial picture quality and lifetime reliability, respectively. Empirical equations were suggested for the analysis of the time dependence of these luminance data. These approaches are expected to be helpful in predicting the luminance properties of backlights based on the luminance data obtained in a limited time window.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.11
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• pp.1038-1042
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• 2005

We have investigated dielectric properties depending on bias voltage in organic light-emitting diodes using 8-hydroxyquinoline aluminum $(Alq_3)$ as an electron transport and emissive material. We analyzed the dielectric properties of organic light-emitting diodes using impedance of characteristics. Impedance characteristics was measured complex impedance Z and phase $\theta$ in the frequency range of 40 Hz to $10^8$ Hz. We obtained complex electrical conductivity, dielectric constant, and loss tangent $(tan\delta)$ of the device at room temperature. From these analyses, we are able to interpret a conduction mechanism and dielectric properties contributed by an interfacial and orientational polarization.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2006.05a
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• pp.135-138
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• 2006

OLEDs are attractive because of possible application in display with low operating voltage, low power consumption, self-emission and capability of multicolor emission by the selection of emissive material. We investigated the effects of deposition rate on the electrical characteristics, physical characteristics and optical characteristics of OLEDs in the ITO(indium-tin-oxide)/N,N'-diphenyl-N,N'-bis(3-methyphenyl)-1,1'-biphenyl-4,4'-diamine(TPD)/tris(8-hydroxyquinoline)aluminum($Alq_3$)/Al device. We measured current density, luminous flux and luminance characteristics of devices with varying deposition rates of TPD and $Alq_3$. It has been found that optimal deposition rate of TPD and $Alq_3$ were respectively $1.5{\AA}/s$ from the device structure. An AFM measurement results, surface roughness of the deposited film was the lowest when deposition rate was $1.5{\AA}/s$.

• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.137-142
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• 2012

The convergent synthetic strategy for the emissive dendrimers having the chromophore at core via the coppercatalyzed 1,3-dipolar cycloaddition reaction between alkyne and azide was described. 2,7-Diazido-9,9-dioctyl-9H-fluorene, designed to serve as the core in dendrimer, was stitched with the alkyne-functionalized Frechettype and PAMAM dendrons by the click chemistry leading to the formation of the corresponding fluorescent dendrimers in high yields. The preliminary photoluminescence studies indicated that 2,7-diazido-9,9-dioctyl-9H-fluorene showed no fluorescence due to the quenching effect from the electron-rich ${\alpha}$-nitrogen of the azido group but the dendrimers fluoresced due to the elimination of the quenching through the formation of the triazole ring.