• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.518-521
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• 2002

New luminescent material, 6,11-Dihydroxy-5,12-naphthacenedione$(Alq_2-Ncd)$ was synthesized. And extended efforts have been made to obtain high-performance electro-luminescent(EL) devices, since the first report of organic light-emitting diodes(OLEDs) based on tris-(8-hydroxy-quinoline)aluminum$(Alq_3)$ Current-voltage characteristics, brightness-voltage characteristics, luminous efficiency and quantum efficiency were measured at room temperature. The maximum wavelength of the EL is at around 504nm and the brightness is up to $2702[cd/m^2]$ with the maximum efficiency up to 3.91 [1m/W]. This study indicates not only the sterical effect but also some other effect would be responsible for the change of the emission wavelength.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1433-1436
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• 2007

Using a blue emitting DPVBi material and red dopant DCJTB, WOLEDs with and without green emitter C6 added in ETL or HTL have been fabricated. The chromaticity color index of WOLEDs without C6 depends strongly on the doping concentration. In addition, manipulating thickness of emitting layer is similar effect such as controlling weight concentration of dopant. While the white color of WOLEDs with C6 added in ETL or HTL depend on position of C6. WOLED of three colors added green dye have been shown turn-on voltage of 3.25V, and EL efficiency 3.05cd/A @9V, $8102\;cd/m^2$, CIE coordinates (0.30, 0.32).

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.798-802
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• 2009

New blue emitting materials of o,p-TP-EPY and m,m-TP-EPY were synthesized using two terphenyl units with different structures in the new core of indenopyrazine. EL spectrum of o,p-TP-EPY was more blue shifted than m,m-TP-EPY, and external quantum efficiency of o,p-TP-EPY was showed improvement of about 60% compared to efficiency of m,m-TP-EPY.

• Journal of the Korean Chemical Society
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• v.57 no.2
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• pp.264-271
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• 2013

Corrosion inhibition of mild steel used in water station in 35 ppm aluminum sulfate and 10 ppm chloride solution by Camellia sinensis leaves extract was studied using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy techniques at $30^{\circ}C$. Results show that the inhibition efficiency increases with increasing concentration of the extract and decreases with increasing temperature. Inhibitive effect was afforded by adsorption of the extract's components which was found to accord with Langmuir adsorption isotherm. Inhibition mechanism is deduced from the temperature dependence of the inhibition efficiency and was further corroborated by the values of activation parameters obtained from the experimental data.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.2
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• pp.15-22
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• 2004

For an ElGamal-type signature scheme using a generate g of order q, it has been well-known that the message nonce should be chosen randomly in the interval (0, q-1) for each message to be signed. In (2), H. Kuwakado and H. Tanaka proposed a polynomial time algorithm that gives the private key of the signer if two signatures with message nonces 0＜$k_1$, $k_2$$\leq$Ο(equation omitted) are available. Recently, R. Gallant, R. Lambert, and S. Vanstone suggested a method to improve the efficiency of elliptic curve crytosystem using integer decomposition. In this paper, by applying the integer decomposition method to the algorithm proposed by Kuwakado and Tanaka, we extend the algorithm to work in the case when ｜$k_1$ ｜,｜$k_2$, ｜$\leq$Ο(equation mitted) and improve the efficiency and completeness of the algorithm.

• Journal of the Korean Chemical Society
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• v.58 no.4
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• pp.359-365
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• 2014

The inhibition effect of cinnamon plant extract as a green corrosion inhibitor for steel in sulfide polluted salt water was studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and electrochemical frequency modulation (EFM). The results showed that cinnamon plant extract in sulfide polluted salt water is a good corrosion inhibitor with inhibition efficiency reached to 80% at 250 ppm of the plant extract. The adsorption of cinnamon obeys Temkin adsorption isotherm, and acts as a mixed-type of inhibitor but dominantly as a cathodic inhibitor in sulfide polluted salt water.

• 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/$m^2$.

• Bulletin of the Korean Chemical Society
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• v.23 no.9
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• pp.1235-1267
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• 2002

A series of 2,5-dialkoxy substituted poly(1,4-phenylenevinylene) derivatives containing a rigid and bulky cyclohexyl group in the side chain, poly[2-(7-cyclohexylheptyloxy)-5-butoxy-1,4-phenylenevinylene] (PBCyHpPV), Poly[2-(6-cyclohexylmethoxyhexyloxy)-5-butoxy-1,4-phenylenevinylene] (PBCyHxPV), Poly[2,5-di-(6-cyclohexylmethoxy-hexyloxy)-1,4-phenylenevinylene] (PDCyHxPV) were synthesized via the Gilch polymerization. The synthesized polymers were soluble in common organic solvents and showed good thermal stability up to $370^{\circ}C$. The maximum absorption of PBCyHpPV, PBCyHxPV and PDCyHxPV as thin films was at 513 ㎚, 515 ㎚, 511 ㎚, respectively. Photoluminescence maximum emission of above polymers appeared at 590 ㎚, 597 ㎚, 590 ㎚, respectively. The electroluminescence (EL) maxima of the polymers appeared around 585-590 ㎚, and also showed another shoulder around 630 ㎚ strongly. PDCyHxPV showed the highest EL efficiency and EL power than those of other polymers due to the dilution effect of the two rigid and bulky cyclohexyl groups.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.952-954
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• 2003

We report the photo-(PL) and electroluminescence (EL) properties of new conjugated compounds based on carbazolyl vinylene moiety, 3,3'-(1,4-phenylene di-2,1-ethenediyl) bis[9-ethyl-(E,E)-9H-carbazole](PEEC) and 3,3'-([1,1'-biphenyl]-4,4'-diyldi-2,1-ethenediyl)bis[9-ethyl-9H-carbazole](BPEEC), as emitting materials. The ITO/m-MTDATA/NPB/BPEEC/Alq3/LiF/Al device shows bluish-green EL spectrum at 490nm and turn-on voltage at 8V. PEEC shows bluish-green EL around ${\lambda}$ max=496nm and turn-on voltage at 6V and 2.4 Cd/A efficiency in ITO/m-MTDATA/NPB/PEEC/Alq3/LiF/Al device.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.948-951
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• 2003

The electroluminescence (EL) properties were studied in organic light-emitting diodes with a red fluorescent dye, 4- (dicyanomethylene)- 2- tert-butyl-6 (1,1,7,7-tetramethyljulolidyl-9-enyl)- 4H- pyran (DCJTB) doped into tris-(8-hydroxyquinoline)aluminum ($Alq_{3}$), rubrene and the mixed matrix of $Alq_3$ and rubrene. The device with DCJTB doped into the $Alq_{3}$:rubrene mixed host shows an efficient red emission from DCJTB with a negligible EL emission from $Alq_{3}$ and a lower EL onset voltage compared to the device with DCJTB doped into the $Alq_{3}$ only host. The quantum efficiency is almost temperature-independent for the device with the $Alq_3:rubrene$ mixed host. The results indicate that recombination of injected electrons and holes occurs on rubrene and subsequent energy transfer to DCJTB dominates in the device with the $Alq_{3}$:rubrene mixed host.