• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.6
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• pp.568-573
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• 2006

We have synthesized new blue light emitting random copolymers, poly(9,9'-n-dioctylfluorene-co-perfluorobenzene-1,4-diyl)s (PFFBs), via Ni(0)-mediated coupling reactions. The weight-average molecular weights ($M_w$) of the PFFB copolymers ranged from 9,000 to 15,000. The PFFB copolymers dissolved in common organic solvents such as THF and toluene. The PL emission peaks of the PFFB copolymers were at around 420, 440, and 470 nm. EL devices were fabricated in ITO/PEDOT/polymer/Ca/Al configurations using these polymers. These EL devices were found to exhibit pure blue emission with approximate CIE coordinates of (0.15, 0.11) at $100cd/m^2$. The blue emissions of these devices might be due to the restriction of the polymer chains to aggregation by introducing of the highly electronegative fluorine moieties. The maximum brightnesses of the PFFB copolymer devices ranged from 140 to $3600cd/m^2$ with maximum efficiencies from 0.2 to 0.6 cd/A. The enhanced efficiency of the PFFB (8/2) copolymer device results from the inhibition of excimer formation by the introduction of the electronegative fluorine moieties into the copolymers.

• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.454-457
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• 2011

We report the preparation of nanocrystalline cobalt ferrite, $CoFe_2O_4$, particles using recycled $Co_3O_4$ and their surface coating with silica using micro emulsion method. Firstly, the $Co_3O_4$ powders were separated from waste cemented carbide with acid-base chemical treatment. The cobalt ferrite nanoparticles with the size 10 nm are prepared by thermal decomposition method using recycled $Co_3O_4$. $SiO_2$ was coated onto the $CoFe_2O_4$ particles by the micro-emulsion method. The $SiO_2$-coated $CoFe_2O_4$ particles were studied their physical properties and characterized by X-ray diffraction (XRD), high resolution-transmission electron microscopy (TEM) analysis and CIE Lab value.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.5
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• pp.429-434
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• 2002

In this paper, multiheterostructure white organic light-emitting device was fabricated by vacuum evaporation. The structure of white organic light-emitting device is ITO/CuPc/TPD/DPBi:DPA/$Alq_3/Alq_3$:DCJTB/BCT/$Alq_3$/Ca/Al. Three primary colors are implemented with DPVBi, Alq$_3$and DCJTB. The maximum EL wavelength of the fabricated white organic light-emitting device is 647nm. And the CIE coordinate is (0.33, 0.33) at 13 V. In the fabrication of white organic light-emitting devices with DCJTB, $Alq_3$, DPVBi, the EL spectrum has two peaks at 492nm, 647nm. Two peaks appeared because the blue light is combined with green light. The maximum wavelength of red light is not changed with applied voltage. After voltage applied, for the first time, the electrons met the holes in the red emission layer and emitted red light. And then the electrons moved to the green emission layer, and blue emission layer continuously. Finally, when all of the emission layer activated, the white light is emitted.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.285-288
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• 1996

The electronic operation of the gas discharge tube is controlled by the electrical energy as sinusoidal waveform in arbitrary frequency range, or as a sequence of pulses at a wide range of duty cycle, the gas composition, the kind of electrode and the vessel geometry. In this paper, the pulsed mode operated gas discharge tube is composed with mixed gas of IIg-Ne ( 10 Torr ), in the tube of 15.0 mm outer diameter and has variable color from red to blue with changing frequency and pulse width in high voltage. As increasing pulse width and frequency in the gas discharge tube, the phenomenons that the electron temperature in the positive column increases and the radiation from atoms of higher upper state energy levels increases, exist. The color have the locus from red (0.4972, 0.3128) to blue (0.2736, 0.2619) in CIE chromacity diagram with increasing pulse width and frequency. The changing method of pulse width and frequency has been shown to be suitable for the luminous color control.

• Journal of the Korean Society of Clothing and Textiles
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• v.37 no.8
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• pp.1130-1138
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• 2013

We examined dyeing properties using cotton, Tencel, general nylon 66 and hollow nylon 66 treated with aqueous and ethanol extracts without mordant. The antimicrobial properties of fabrics treated with Artemisia extracts against gram positive Staphylococcus aureus (S. aureus) and gram negative Klebsiella pneumonia (K. pneumonia) were also examined. The dying solution concentrations were determined from a calibration curve of the concentration and absorbance of Artemisia extracts. FTIR spectra confirmed that antimicrobial components and colorants (such as 1,8-cineol, thujone, caffeoylquinic acid and chlorophyll) were more present in ethanol extract than in aqueous extract. Nylons had higher $a^*$ and $b^*$, and lower $L^*$ values than cellulose fabrics dyed with aqueous solutions of Artemisia extracts; however, the dyed nylon fabrics were brown. Fabrics dyed with ethanol-extract added solutions were greener and had higher antimicrobial properties than those dyed with aqueous solutions; however, they faded and lost their antimicrobial properties after laundering. Fabrics regained their antimicrobial properties (especially against S. aureus) by the spraying of Artemisia ethanol extract; therefore, the application of Artemisia ethanol extract onto underwear is expected to relieve atopic dermatitis.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.2018-2019
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• 2007

Organic light emitting diodes (OLEDs) show a lot of advantages for display purposes. Because OLEDs provide white light emission with a high efficiency and stability, it is desirable to apply OLEDs as an illumination light source and back light in LCD displays. We synthesized new emissive materials, namely $Zn(HPB)_2$ and Zn(HPB)q, which have a low molecular compound and thermal stability. We studied white OLEDs using $Zn(HPB)_2$ and Zn(HPB)q. The fundamental structures of the white OLEDs were ITO / NPB (40 nm) / $Zn(HPB)_2$ (40 nm) / Zn(HPB)q (20 nm) / LiAl (120nm). As a result, we obtained a maximum luminance of $15325cd/m^2$ at a current density of $997\;mA/cm^2$. The CIE (Commission International de l'Eclairage) coordinates are (0.28, 0.35) at an applied voltage of 9.75 V.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1373-1374
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• 2007

We has been synthesized $(POB)_{2}Ir(pic)$ as a red emitting materials and evaluated in the organic light emitting diodes (OLED). The layer of $Alq_3$ doped with $(POB)_{2}Ir(pic)$ as emitters has been demonstrated. The structure of the device is ITO/ NPB (40 nm) / $Zn(HPB)_2$ (40 nm)/ $Alq_3$ : $(POB)_{2}Ir(pic)$ (30 nm) / LiF / Al. We varied the doped rate of $(POB)_{2}Ir(pic)$. The doped rate is 0.4 %, 0.6%, 0.8 and 1.2%, respectively. When the doped rate of the $Alq_3$:$ Ir(POB)_{2}(pic)$ was 0.6%, white emission is achieved. The Commission Internationale de l'Eclairage (CIE) coordinates of the white emission are (0.316, 0.331) at an applied voltage of 10.75V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.438-440
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• 2005

At present, characteristic of high color reproduction for LCD TV is needed in Display market according to start mass production of LCD TV. Therefore development target for LCD is focused on improvement of color reproduction. The improving methods of high color reproduction are alteration of color Filter or Red, Green, Blue phosphor alteration of CCFL. But decrease of luminance and panel transmittance is caused by alteration of Color Filter. Accordingly, we completed LCD with high color reproduction by the most suitable emission spectrum of CCFL phosphor at panel with conventional color filter. In this experiment, we knew that LCD applied to CCFL with high color rendering characteristic had color reproduction range of 81% compared with NTSC in CIE color coordinate. According to increase of intensity peak and alteration of Red, Green, Blue phosphor spectrum, we made LCD with high color reproduction characteristic. In conclusion we achieved improvement of color reproduction ratio by alteration of CCFL phosphor without changing color filter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.428-429
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• 2006

In this thesis, verifies electrical-optical characteristics of phosphorescent materials. basic structure of fabricating devices is glass/ITO/$\alpha$-NPD($300{\AA}$)/CBP:Guest($300{\AA}$)/BCP($80{\AA}$)/$Alq_3(100{\AA})$/Al($1000{\AA}$). In efficiency, fabrication of organic light emitting diodes using $Ir(btp)_2acac$ phosphorescent material is external quantum efficiency 0.268% as doping concentration 3%. At CIE coordinates, phosphorescent material $Ir(btp)_2acac$ following materials moves high purity red color(x=0.6686, y=0.3243). The brightness shows $285cd/cm^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.416-417
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• 2006

Organic light emitting diodes (OLEDs) show a lot of advantages for display purposes. Because OLEDs provide white light emission with a high efficiency and stability, it is desirable to apply OLEDs as an illumination light source and back light in LCD displays. We synthesized new emissive materials, namely [2-(2-hydroxyphenyl)benzoxazole] ($Zn(HPB)_2$) and [(2-(2-hydroxyphenyl)benzoxazole)(8-hydoxyquinoline)] (Zn(HPB)q), which have a low molecular compound and thermal stability. We studied white OLEDs using $Zn(HPB)_2$ and Zn(HPB)q. The fundamental structures of the white OLEDs were ITO/PEDOT:PSS (23 nm)/NPB (40 nm)/$Zn(HPB)_2$ (40 nm)/Zn(HPB)q (20 nm)/$Alq_3$ (10 nm)/LiAl (120 nm). As a result, we obtained a maximum luminance of $15325\;cd/m^2$ at a current density of $997\;mA/cm^2$. The CIE(Commission International de l'Eclairage) coordinates are (0.28, 0.35) at an applied voltage of 9.75 V.