• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.10
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• pp.4590-4599
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• 2011

The Color shift phenomenon is becoming a major degradation factor of the emitting color purity in the organic emitting diodes which is generating a plurality of colors. In this study, the basic structure of organic light emitting diode device is comprised of ITO/${\alpha}$-NPD/$Alq_3$:DCJTB[wt%]/$Alq_3$/Mg:Ag, we have carry out numerical simulation of the electric-optical characteristics in organic light emitting diode device to estimate the mechanism of color shift phenomenon. We have investigated the causes of the color shift through the change of DCJTB doping concentration ratio. As the result, we have confirmed that the changes of the recombination rate which generated by trapped electrons and holes is one of the major factors for the color shift phenomenon.

• Korean Journal of Environmental Agriculture
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• v.26 no.4
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• pp.337-342
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• 2007

To obtain the data on the risk assessment of residue levels of organophosphorus and organochlorine pesticides in fresh ginseng and red ginseng extract, the residual pesticides in samples are surveyed with GC-NPD and GC-ECD for quantitative analysis and GC-MSD for qualitative analysis. The residual organophosphorus pesticides, such as diazinon, pyrimethanil, tolclofos-methyl, metalaxyl, diethofencarb, parathion, cyprodinil, tolylfluanid and kresoxim-methyl, are not detected in fresh ginseng from Punggi. The residual organophosphorus pesticides except tolclofos-methyl are not detected in fresh ginseng from Sangju. Average amount of tolclofos-methyl in fresh ginseng from Sangju are $0.054{\pm}0.008\;mg/kg$, representing $18{\pm}2%$ of MRL of 0.03 mg/kg on fresh ginseng in Korea. The residual organochlorine pesticides, such as BHC isomer, DDT isomer, aldrin, azoxystrobin, captan, cypermethrin, deltamethrin, dieldrin, difenoconazole, endosulfan-sulfate, endrin, fenhexamid, quintozene, ${\alpha}$-endosulfan and ${\beta}$-endosulfan, are not detected in fresh ginseng from Punggi and Sangju. The residual organophosphorus and organochlorine pesticides in red ginseng extract from Punggi and Sangju are not detected.

• Applied Chemistry for Engineering
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• v.18 no.6
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• pp.537-544
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• 2007

This study was carried out to investigate adsorption characteristics of residual pesticides on an adsorbent. $Bauxsol^{TM}$ and mackban-stone as adsorbent were used. Analytical method for residual pesticides was established by GC/NPD and $GC/{\mu}ECD$. Pesticides used in this study were ${\alpha}$-endosulfan, ${\beta}$-endosulfan, pendimethalin and chlorpyrifos-methyl, fenitrothion, and recovery rates were more than 97%. Adsorption rate on an adsorbent was decreased in order of endosulfan, chlorpyrifos-methyl, pendimethalin, fenitrothion. Organochlorine pesticides showed higher removal rate than the other pesticides. $Bauxsol^{TM}$ gave both chemical decomposition and physical adsorption. Mackban-stone gave only physical adsorption on the other hand. The high pH and chloric ions structure of eluted solution have greatly affected at chemical resolution. The removal rate of pesticides was increased due to the physical property of adsorbent, i.e. high porosity. The above adsorbent is to be a candidate to remove residual pesticides in water and pond of links.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.579-581
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• 2004

A new DCM derivative containing the phenoxazine moiety (DCPXZ) has been synthesized for use as a red fluorescent dye molecule in organic light-emitting diodes (OLEDs). The photoluminescence and electroluminescence properties of DCPXZ were examined. The maximum photoluminescence of DCPXZ in chloroform solution ($10^{-5}$ mol) was observed at 616 nm. EL devices were fabricated with the structure ITO/PEDOT-PSS/Cu-PC(15nm)/${\alpha}$-NPD(45nm)/$Alq_3$:DCPXZ(30nm)/$Alq_3$(30nm)/LiF(0.5nm)/Al. The maximum EL emission for the 2.0% DCPXZ-doped device was at 608 nm with CIE coordinates (0.57, 0.42). The EL device exhibited a maximum brightness of 15,000 cd/$m^2$ at 19.4 V and a power efficiency of 1.04 lm/W at a luminance of 100 cd/$m^2$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.9
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• pp.802-807
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• 2007

We have developed red phosphorescent top emission organic light-emitting diodes with transparent metal cathodes deposited by using thermal evaporation technique. Phosphorescent guest molecule, BtpIr(acac), was doped in host CBP for the red phosphorescent emission, Ca/Ag, Ba/Ag, and Mg/Ag double layers were used as cathode materials of top emission devices, which were composed of glass/Ni/2TNATA(15 nm)/${\alpha}$-NPD(35 nm)/CBP:BtpIr(acac)(40 nm, 10%)/BCP(5 nm)/$Alq_3$(5 nm)/cathodes. The optical transparencies of these metal cathodes strongly depend on underlying Ca, Ba, and Mg layers. These layers also strongly affect the electrical conduction and emission properties of the red phosphorescent top emission devices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.276-277
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• 2006

본 연구에서는 인광 발광 물질인 host재료, CBP에 guest로 인광색소인 $Ir(ppy)_3$을 첨가하여 광학적, 전기적 특성을 보았다. $Ir(ppy)_3$ 색소를 서로 다른 중량비로 첨가할 때의 소자들의 특성을 평가하였다.$ Ir(pppy)_3$을 3.125%의 중량비로 하였을 때 가장 좋은 휘도특성을 보였다. 소자의 기본구조는 glass/ITO/${\alpha}-NPD(300{\AA})$/CBP:$Ir(ppy)_3(300{\AA})$/$BCP(80{\AA})$/$Alq_3(200{\AA})$)/$Al(1000{\AA})$로 하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.530-532
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• 2008

Inorganic metal multi-layer(IMML) consisting of Al/Al:SiO/Al was developed as a cathode for OLED to reduce the reflectance generated from ambient light. Device structure of green OLED was ITO/2-TNATA/$\alpha$-NPD/$Alq_3$:C545T/Balq/$Alq_3$/LiF/IMML and IMML was composed of three different layers: thin aluminum layer, aluminum layer doped with silicon monoxide and thick aluminum layer. Average reflectance of green OLED was 9.63% while that of conventional OLED with or without polarizer showed the average reflectance of 8.54% and 66% respectively at visible range from 380 nm to 780 nm.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.944-947
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• 2003

We report efficient white organic electroluminescent devices consisting of a blue-emitting layer of 9,10-bis[(2",7"-di-t-butyl)-9',9"-spirobifluorenyl]anthracene (TBSA) and a red-emitting layer of 4-dicyanomethylene-2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[i,j]quinolizin-8-yl)vinyl]-4H-pyran) (DCM2) doped into 4,4'bis[N-(1-napthyl)-N-phenyl-amino]-biphenyl (${\alpha}-NPD$). The device shows the CIE coordinates of (0.32, 0.37). The external quantum efficiency is about 3.4 % and the luminous efficiency is about 3.9 lm/W at luminance of 100 $cd/m^{2}$. The maximum luminance is about 45,400 $cd/m^{2}$ at 11.5 V.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.12
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• pp.1143-1147
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• 2005

In this study, we report an improved efficiency of Organic light emitting diodes(OLEDs), using $UV/O_3$ treated anode and different cathode. We investigated the efficiency of OLEDs by $UV/O_3$ treatment of ITO surface. We Performed $UV/O_3$ treatment and found that $UV/O_3$ treatment enhanced the performance of OLEDs. The fundamental structure of the OLEDs was ITO $anode/{\alpha}-NPD/Alq_3/Al$ or Li:Al cathode. The Li:Al can improve the OLEDs efficiency dramatically in cathode because it has lower work function than Al. Current-voltage, Luminance-voltage characteristics and luminance efficiency were measured at room temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.9
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• pp.873-877
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• 2006

We have fabricated top omission organic light emitting diodes with transparent Ba/Ag double layer cathodes deposited by using thermal evaporation method. The device structure was $glass/Ni(200nm)/2-TNATA(15 nm)/{\alpha}-NPD(15nm)Al_{q3}:C545T\;(1%,\;35nm)/BCP(5nm)/Ba(10nm)/Ag(8nm)$. The optical transmittance of the Ba(10 nm)/Ag(8 nm) layer was over 60 % in the visible wavelength region. The maximum efficiency of the device was $13.7\;cd/A\;at\;0.69\;mA/cm^{2}$ and the efficiency of over 10 cd/A was achieved at wide range of current densities and luminances.