• Journal of the Korean institute of surface engineering
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• v.40 no.2
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• pp.77-81
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• 2007

To investigate the characteristics of green light-emitting OLED device, C545T material with $Alq_3$ was doped in the OLED device of $ITO(1500)/2-TNATA(400{\AA})/NPB(80{\AA})/Alq_3:C545T(160{\AA})/Alq_3(240{\AA})/LiF(3{\AA})/Al(2400{\AA})$ structure, which was used as a activator at the respective concentration of 0.5 vol.%, 1 vol.%, 2 vol.% and 3 vol.%. It was observed from the experiments that the device efficiency firstly increased with the increase of C545T concentration and the maximum efficiency of 10.9 cd/A and 4.28 lm/W was obtained at C545T concentration of 1 vol.%, and then the device efficiency decreased as the C545T activator concentration increased above 2 vol.% contents, while the longest lifetime of over 750 hours was obtained at C545T concentration of 1 vol.%.

• Journal of the Korean Vacuum Society
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• v.19 no.3
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• pp.184-189
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• 2010

Organic light-emitting diodes (OLEDs) with single emissive layer structures using two fluorescent dopants were fabricated and the device was composed of ITO / NPB ($700{\AA}$) / MADN : C545T - 1.0% : DCJTB - 0.3% ($300{\AA}$) / Bphen ($300{\AA}$) / LiF ($10{\AA}$) /Al ($1,000{\AA}$). C545T and DCJTB were functioned as green fluorescent dye and red fluorescent dye under MADN as host material. Concentrations of C545T and DCJTB was changed in emissive layer of MADN. Optimized OLED device using two fluorescence dopants shows emission efficiency of 8.42 cd/A and luminescence of 3169 cd/$m^2$at 6 V with CIE color coordinate, (0.43, 0.50). Electroluminescence of optimized OLED showed two peak at 500 and 564 nm according to C545T and DCJTB. These results indicate that F$\ddot{o}$ster energy transfer energy transfer was from MADN to C545T and rather than to DCJTB continuously.

• Journal of the Microelectronics and Packaging Society
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• v.13 no.1 s.38
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• pp.51-55
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• 2006

The green emitting high performance OLEDs using the $Alq_3$-C545T fluorescent system have been fabricated and characterized. In the device fabrication, 2-TNATA [4,4',4'-tris(2-naphthylphenyl-phenylamino)-triphenylamine] as a hole injection material and NPB [N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine] as a hole transport material were deposited on the ITO(indium thin oxide)/glass substrate by vacuum evaporation. And then, green color emission layer was deposited using $Alq_3$ as a host material and C-545T[10-(2-benzothiazolyl)-1,1,7,7- tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-[1]/benzopyrano[6,7,8-ij]-quinolizin-11-one] as a dopant. Finally, small molecule OLEDs with structure of ITO/2-TNATA/NPB/$Alq_3$:C545T/$Alq_3$/LiF/Al were obtained by in-situ deposition of $Alq_3$, LiF and Al as the electron transport material, electron injection material and cathode, respectively. Green OLEDs fabricated in our experiments showed the color coordinate of CIE(0.29, 0.65) and the maximum power efficiency of 7.3 lm/W at 12 V with the peak emission wavelength of 521 nm.

• Proceedings of the Korean Vacuum Society Conference
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• 2009.08a
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• pp.388-388
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• 2009

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.827-834
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• 2010

We have performed numerical simulations of the electrical characteristics for multi-layer organic light emitting diode devices with doped emitting layer using a commercial simulation program. In this paper, the basic structure consists of the ITO/NPB/$Alq_3$:C545T(%)/$Alq_3$/LiF/Al, four devices that were composed of $Alq_3$ as the host and C545T as the green dopant with different concentration, were studied. As the result, the variations of the doping concentration rate of C545T have a effect on the voltage-current density characteristics. The voltage-current characteristics are quite consistent with the results which were experimentally determined in a previous reference paper. In addition, the voltage-luminance characteristics were greatly improved, and the luminous efficiency was improved three times. In order to analyze these driving mechanism, we have investigated the distribution of electric field, charge density of the carriers, and recombination rates in the inner of the OLED devices.

• Communications for Statistical Applications and Methods
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• v.12 no.3
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• pp.545-556
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• 2005

Hjort(1990) obtained the nonparametric Bayes estimator $\^{F}_{c,a}$ of $F_0$ with respect to beta processes in the random censorship model. Let $X_1,{\cdots},X_n$ be i.i.d. $F_0$ and let $C_1,{\cdot},\;C_n$ be i.i.d. G. Assume that $F_0$ and G are continuous. This paper shows that {$\^{F}_{c,a}$(u){\|}0 < u < T} converges weakly to a Gaussian process whenever T < $\infty$ and $\~{F}_0({\tau})\;<\;1$.

• Kyungpook Mathematical Journal
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• v.50 no.4
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• pp.545-556
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• 2010

A good amount of work has been done on degree of approximation of functions belonging to Lip${\alpha}$, Lip($\xi$(t),r) and W($L_r,\xi(t)$) and classes using Ces$\`{a}$ro, N$\"{o}$rlund and generalised N$\"{o}$rlund single summability methods by a number of researchers ([1], [10], [8], [6], [7], [2], [3], [4], [9]). But till now, nothing seems to have been done so far to obtain the degree of approximation of functions using (N,$p_n$)(C, 1) product summability method. Therefore the purpose of present paper is to establish two quite new theorems on degree of approximation of function $f\;\in\;Lip({\alpha},r)$ class and $f\;\in\;W(L_r,\;\xi(t))$ class by (N, $p_n$)(C, 1) product summability means of its Fourier series.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.8
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• pp.638-644
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• 2010

We have carry out numerical simulation of the electric-optical characteristics of organic light emitting diodes with gradient-doped emitting layer which were reported to be effective in improving luminous efficiency and lifetime. In this paper, the basic structure is comprised of ITO/NPB/$Alq_3$:C545T[%]/$Alq_3$/LiF/Al, six devices by separating the emitting layer of $Alq_3$:C545T[%] were studied. As the result, the uniformly-doped devices exhibited superior luminous efficiency-current density characteristics over conventional undoped device. In the case of gradient-doped devices, electric-optical characteristics were improved similar to uniformed-doped devices, unusually the distribution of traped-charge density in the OLED devices was shown as the staircase.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.04a
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• pp.81-82
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• 2006

Doping is a well-known method for improving electroluminescent (EL) efficiency of organic light emitting diodes. In our study, doping with 2 materials simultaneously, we could achieve improved EL efficiency. The emission layer was tris-(8-hydroxyquinoline)aluminum, and the 2 dopants were N,N'-dimethyl-quinacridone (DMQA) and 10-(2-Benzothiazolyl)-2, 3, 6, 7-tetrahydro-1,1,7,7,-tetramethyl 1-1H, 5H, 11H-[1] benzopyrano [6,7,8-ij]quinolizin-11-one (C-545T). The EL intensity of co-doped device was nearly flat, it shows that co-doping technique could be a effective way to improve the EL efficiency. EL efficiency of Single-doped device based on DMQA and C-S45T were ~6.47Cd/A and ~7.45Cd/A, respectively. Co-doped device showed higher EL efficiency of ~8.30Cd/A.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.545-548
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• 1999

The purpose of this study is application of strengthening technique of R/C concrete bridge by standardization of repair and rehabilitation. For that, experiment to bridge is necessary, and through the experiment, this study can identify the efficiency o applied method and analysis of design parameters with can't get in the laboratory experiment. This study will prove the structural behavior of R/C type girder bridge which is deteriorated but repaired and rehabilitation from standardized strengthening method with fiber plastic.