• 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.

• Journal of the Korean Chemical Society
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• v.44 no.6
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• pp.541-546
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• 2000

Methods to determine L-dopa(L-3,4-dihydroxyphenylalanine) in aqueous solution by spectrofluorimetry based upon the ligand sensitized luminescence of Tb(III) ion L-dopa complex have been studied. Tb(III) ion and Lu(III) ion were used as ligand sensitized fluorescencer and co-fluorescence enhancer, respectively. The effects of excitation wavelength, pH, concentration of Tb(III) ion, concentration of Lu(III) ion and emission wavelength on the fluorescence intensity were investigated. The fluorescence intensity of the Tb(III) ion L-dopa complex was further increased with addition of Lu(III) ion. The calibration curve for L-dopa was linear over the range from 5.0 ${\times}$ $10^{-7}$ M to 1.0${\times}$ $10^{-4}$ M and the detection limit was 4.0 ${\times}$ $10^{-8}$ M under the optimal experimental conditions of 300 nm, 8.0, 1.0 ${\times}$ $10^{-4}$ M and 545 nm for excitation wavelength, pH, concentration of Tb(III) ion and emission wavelength, respectively. When Lu(III) ion was added to Tb(Ⅲ) ion L-dopa complex, the concentration range of linear response and detection limit were 1.0${\times}$$10^{-8}$ M to 2.0 ${\times}$ $10^{-4}$ M and 1.0 ${\times}$ $10^{-9}$ M, respectively under the optimal experimental conditions of 300 nm, 8.5, 1.0 ${\times}$ $10^{-5}$ M, 1.0 ${\times}$ $10^{-5}$ M, 545 nm for excitation wavelength, pH, concentration of Tb(III) ion, concentration of Lu(III) ion and emission wavelength, respectively.

• Korean Journal of Food Science and Technology
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• v.34 no.3
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• pp.454-458
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• 2002

The effect of antibrowning agents such as PVPP (polyvinylpolypyrrolidone), bentonite, gelatin, celite 545, tannic acid and sodium sulfite in apple concentrate was investigated for the control of enzymatic browning by comparing physicochemical properties (pH, color, turbidity), polyphenoloxidase activity and contents of polyphenol compounds. In color value, apple concentrate containing PVPP showed higher L value (lightness) than control and other antibrowning agents. The turbidity (absorbance at 660 nm) of apple concentrate added PVPP, gelatin celite 545, tannic acid and sodim sulfite were 0.003, 0.038, 0.018 and 0.022, respectively. PVPP was regarded to remove suspended solids effectively. Polyphenoloxidase activity and polyphenolics(catechol, catechin, chlorogenic acid, epicatechin) content of apple concentrate used PVPP significantly reduced. Therefore PVPP was proved to be effective for enzymatic antibrowning agent considering to color, turbidity, polyphenoloxidase activity and polyphenol compounds in apple concentrate.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.220-220
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• 2016

본 연구에서는 녹황색 빛을 내는 NaY(WO4)2:Tb3+ 형광체 파우더를 하소 350도에 1시간 소결 950도에 4시간 고상반응법으로 합성하였으며, 파우더는 X-ray diffraction과 PL 장비를 이용하여 측정하였다. XRD 분석은 Tb3+이온 도핑농도에 의한 순수한 NaYWO4 상을 나타내었다. Fig.1 220-330nm에서 관찰되는 넓은 밴드는 $O2-{\rightarrow}W6+$에 의해 발생한 LMCT(ligand to metal charge transfer)이고, Tb3+에서 WO42-그룹으로 에너지 전달에 의해서 생긴다. 이것의 최대세기는 272nm 이다. LMCT 옆 330-390nm에 관찰되어지는 약한 강도와 넓은 밴드는 Tb3+ 4f8의 f-f transition에 의해 발생한다. Fig.2에서 보여 지듯이$ 5D4{\rightarrow}7F6$, 7F5, 7F4, 7F3는 파장 489nm, main peak인 545nm (Green,초록색), 588nm (orange, 주황색), 620nm (Red, 적색)에서 Peak가 나타났으며, Tb3+이온의 함량비가 0.08mol일 때 최대 발광이 관측 되었다.

• Journal of Bio-Environment Control
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• v.31 no.2
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• pp.104-113
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• 2022

Plants under the genus Orostachys have been known as medicinal plants. This study deems to determine the growth and leaf color of Orostachys japonica and O. boehmeri when subjected to various LED light sources. A total of seven LED light treatments were used, i.e. red (630 nm), green (520 nm), blue (450 nm), purple (650 and 450 nm), 3000 K white (455, 600 nm), 4100 K white (455, 590 nm), and 6500 K white (450, 545 nm) LEDs. Results showed that O. japonica plants showed favorable growth under 4100 K white LED, while O. boehmeri plants had a positive growth response under white light LEDs (3000, 4100, and 6500 K). In leaf color analysis, the use of green LED showed the greatest change in CIELAB L^* and b^* values which were relatively higher compared to other treatments indicating that leaves turned yellowish. Further statistical analysis using Pearson's correlation also suggested that there is a small negative association between dry weight and b^* values of O. japonica, and a negative moderate association between plant weights (fresh and dry weight) and leaf color (L^* and b^*) and positive association between said plant weights and a^* color values of O. boehmeri. Therefore, it is recommended to cultivate O. japonica under 4100 K white LED and O. boehmeri under 3000, 4100, 6500 K white LEDs.

• Journal of the Optical Society of Korea
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• v.11 no.1
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• pp.44-48
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• 2007

A two-stage gain-clamped erbium doped fiber amplifier (GC-EDFA) using a pump laser diode and a 16 channel wavelength division multiplexing (WDM) with 0.8 nm spacing in C band of $1,545{\sim}1,560nm$ wavelength is experimentally demonstrated for a burst packet mode optical switching system.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.221-221
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• 2016

최근에 희토류 이온이 도핑된 텅스텐산(tungstates) 형광체에 대한 연구가 재조명되고 있다. 텅스텐산 형광체는 우수한 광학적 특성과 높은 화학적 안정성을 나타내기 때문에 X-선 증강 스크린(X-ray intensifying screens), 광고판용 형광 램프, 발광 다이오드, 레이저, 섬광체(scintillator), 전계방출 디스플레이 영역에 그 응용성을 넓히고 있다. 본 연구는 모체 결정 MgWO4에 희토류 이온인 Tb3+와 융제(flux)의 몰 비를 변화 시켜 고상반응법을 사용하여 합성을 하였다. 합성한 형광체를 여기 파장 281 nm로 제어하였을 시, 545 nm의 녹색 발광 스펙트럼을 관찰 하였다. Tb3+이온이 0.10 mol일 때, 가장 발광 세기가 컸으며, 몰비가 증가 할수록 발광의 세기는 점차 커지다가 0.12 mol에서 작아졌다. 주 발광 신호 이외에도 489 nm, 586 nm, 621 nm에서 상대적으로 작은 발광 스펙트럼을 보였다. XRD를 통해 분석한 결정구조는 단사정계임을 알 수 있었으며 주 피크는 $23.9^{\circ}$에서 발생 하였고 이는 (110)면에서 발생한 회절 신호이다.

• Macromolecular Research
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• v.11 no.3
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• pp.194-197
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• 2003

A new 2,5-di(t-octylphenoxy) group substituted poly(p-phenylenevinylene) derivative was synthesized by Gilch polymerization. The obtained polymer was characterized by NMR, FT-IR, and chemical analysis and completely soluble in common organic solvents. The polymer showed good thermal stability with T$_{g}$ of 105$^{\circ}C$. The polymer dissolved in chloroform showed maximum emission at 514 nm with a shoulder peak at around 560 nm. The EL spectrum of the ITO/PEDOT/TOP-PPV/Al device was observed maximum emission at 545 nm with a shoulder peak at around 585 nm.m.

• Journal of Information Display
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• v.9 no.3
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• pp.23-27
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• 2008

This paper reports that well-balanced white emission with three primary colors can be achieved with a simple white organic light-emitting diode (WOLED) structure of ITO / $\alpha$-NPD (50 nm) / $\alpha$-NPD: Btp2Ir(acac) (8 wt%, 6 nm) / $\alpha$-NPD (5 nm) / BCP (3 nm) / $Alq_3$: C545T (0.5 wt%, 10 nm) / $Alq_3$ (40 nm) / LiF (0.5 nm) / Al (100 nm). The external quantum efficiency of the device reached 3.8% at a current density (luminance) of 4.6 mA/$cm^2$ (310 cd/$m^2$), and the maximal luminance of the device reached 19,000 cd/$m^2$ at 11.5 V. The insignificant blue shift of the emitting color with an increasing current density can be attributed to the narrowing of the exciton formation zone width.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.05a
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• pp.88-91
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• 1993

In this study 9.5/65/35 PLZT was selected which has the excellent quadratic electro-optic property and slim-loop. It was fabricated by the methods of vacuum hot-pressing and sintering. The electrode of color filter was evaporated using the interdigital type masks. Hysteresis and transmission characteristics were measured. The coercive field and the nontransmited field were correlative. Aging effect was measured according to time at same temperature. Wavelengths of RGB were chosen 700[nm] for red, 545[nm] for green and 435[nm] for blue by the standard of the Commission Internationale del Eclaiage.