• Korean Journal of Materials Research
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• v.8 no.7
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• pp.601-606
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• 1998

The $SrTi0_3$:Al, Pr red phosphors were prepared by solid state reaction method. Phosphor preparation parameters such as sintering temperature and time were optimized for the photoluminescence(PU intensity and the cathodoluminescence(CL) intensity. Powder samples showed the characteristic X-ray diffraction patterns of the perovskite structure and the average particle size of 3~5/$\mu\textrm{m}$ for particle size distribution(PSD) analysis. Also, scanning electron microscopy for the powder samples showed that the particles are reasonably crystallized with spherical shape. Especially, higher low voltage CL properties of $SrTi0_3$:Al, Pr phosphors than commercial $Y_2O_3$:Eu phosphors are expected to be applied for a low voltage field emission display(FED).

• Electrical & Electronic Materials
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• v.10 no.8
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• pp.763-769
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• 1997

In this study we have synthesized Zno:Eu phosphors under various sintering atmospheres and temperatures. The analysis of X-ray diffractometer measurement indicates that for Zno:EuCl$_3$ phosphors sintered in air and vacuum 뗘 exists in the host lattice as Eu$_2$O$_3$and EuOCl respectively. From the photoluminescence for the phosphors sintered in vacuum Eu removes the broad-band emission of the ZnO host consequently isolating the red emission due to Eu$^{3+}$ ion and improves the color purity of red emission. The photoluminescence excitation and time resolving spectrum measurements suggest that energy-transfer process occurres from the self-activated defect center in ZnO host the Eu$^{3+}$ ion which exist in the host lattice in the form of EuOCl.

• Korean Journal of Food Science and Technology
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• v.11 no.3
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• pp.166-170
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• 1979

A rapid and simple method for detecting chemical preservatives was attempted on the basis of emitted fluorescence at the illumination of UVSL-25 mineral light. Absorption and fluorescence spectra of powdered samples dispersed in liquid paraffin revealed characteristic patterns depending on chemical preservatives. Detection of chemical preservatives was more readily accomplished by simultaneous comparison of spectral characteristics at long and short wave ranges of the exciting light.

• Journal of the Korean Society of Radiology
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• v.15 no.3
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• pp.391-399
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• 2021

Eu²⁺ doped polyphosphate NaSr(PO₃)₃ blue-emitting phosphors were synthesized by the conventional solid state method in a reductive atmosphere. The phase formation of NaSr(PO₃)₃ phosphors were characterized by using the X-ray powder diffraction (XRD) measurement. The photoluminescence emission and excitation spectra of the NaSr(PO₃)₃:Eu²⁺ phosphor, and decay curves were measured. Under the near-UV excitation, the phosphor exhibits a band emission around 420 nm assigned to the 4f⁶5d→f7(8S^7/2) transition of Eu²⁺. The temperature dependent emission spectra and decay curves were measured to elevate the thermal properties of the Eu²⁺ doped phosphors. The as-prepared NaSr(PO₃)₃:Eu²⁺ phosphors show a strong temperature dependent performance, which can serve as a promising temperature sensor.

• Journal of the Korean Ceramic Society
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• v.36 no.3
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• pp.319-324
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• 1999

기존의 고상 반응법에 의해 합성된 YNbO4 : Bi 형광체의 발광특성을 개선하기 위하여 B2O3 융체 첨가법으로 형광체를 합성하고, 빛발광(PL) 및 저전압 음극선발광(CL)을 측정하였다. PL 및 CL 모두 415~440 nm 영역에서 강한 청색 발광 스펙트럼을 나타냈으며, 고상 반응의 경우와 마찬가지로 Y/Nb 비율이 화학 양론상의 1:1인 경우보다 결함구조를 인위적으로 조절한 51/49나 54/46에서 최대의 발광강도를 보였다. 한편, 고상 반응에서는 125$0^{\circ}C$에서 4시간 열처리하는 것이 최대의 발광효과를 나타냈으나, B2O3융제를 첨가하고 110$0^{\circ}C$에서 열처리한 시료가 결정성이 좋고 입자의 크기 및 형태가 균일하여 PL뿐만 아니라 CL에서도 우수한 발광특성을 보였다. B2O3융제를 첨가하는 방법으로 열처리 온도를 낮추고 입자크기와 형태를 조절하여 형광체의 휘도를 개선할 수 있었다.

• Journal of the Korean Chemical Society
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• v.38 no.12
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• pp.857-863
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• 1994

The absorption and fluorescence spectroscopic studies on the interaction between thionine (TH) and sodium dodecyl sulfate (SDS) have been carried out. The absorption and fluorescence spectral changes of TH with the changes of concentration of SDS are interpreted in terms of i) the aggregation of TH-SDS complex, ii) the stacking process of dye molecules by the association of the TH-SDS complex, iii) breakdown of the stacking due to the formation of dye-rich induced micelles, iv) redistribution of dye molecules in the surface of SDS micelles.

• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.826-831
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• 2018

This study presents fabrication of bi-compartmental particles labeled by multiple fluorescence. To compartmentalize fluorescent expression at the particle, two fluorescent dyes with less overlap of the excitation and emission spectra are selected. To ensure the fluorescence stability, the fluorescent dyes contain acrylate functional groups in the molecules so that they can be cross-linked together with monomers constituting the particle. Strong fluorescent expression and compartmentalization were observed at the particle fabricated using the selected fluorescent dyes through confocal microscopy. Furthermore, long-term fluorescence stability was verified by measuring fluorescent expression and intensity for 4 weeks. We anticipate that the bi-compartmental particles labeled by multiple fluorescence can be widely used for multi-target drug delivery system, analysis of 3 dimensional Brownian motion, and investigation of 3 dimensional complex self-assembled morphologies.

• KSBB Journal
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• v.20 no.4
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• pp.299-304
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• 2005

A two-dimensional (2D) spectrofluorometer was used to monitor various fermentation processes with recombinant E. coli for the production of 5-aminolevulinic acid (ALA). The whole fluorescence spectral data obtained during a process were analyed using artificial neural networks, i.e. self-organizing map (SOM) and feedforward backpropagation neural network (BPNN).Based on the classified fluorescence spectra a supervised BPNN algorithm was used to predict some of the process parameters. It was also shown that the BPNN models could elucidate some sections of the process performance, e.g. forecasting the process performance.

• Journal of the Korean Ceramic Society
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• v.40 no.7
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• pp.709-714
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• 2003

Eu doped $Y_2$ $O_3$ nanoparticles were prepared with the solvothermal synthesis using the ethyleneglycol solvent at 20$0^{\circ}C$ for 3-5 h and then annealed in air at 1000-140$0^{\circ}C$ for 2-4 h. The X-ray diffraction pattern of annealed crystals at 100$0^{\circ}C$ for 2 h could be indexed as pure cubic cell of $Y_2$ $O_3$ phase with lattice parameters a=10.5856 $\AA$ which is very close to the reported data (JCPDS Card File, 41-1105 a=10.6041 $\AA$). Average size of prepared phosphor particles have about 100 nm, which were spherical morphology. The phosphor particle sizes decreased and the emission intensity increased at the annealing temperature. Though PL spectrum analysis, the 3% Eu doped $Y_{2-x}$ $O_3$:E $u_{x}$ $^{3+}$(x=0.06) phosphor showed the excitation spectrum at 250 nm wavelength and the maximum emission spectrum at 611 nm wavelength.

• Journal of the Korean Chemical Society
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• v.46 no.4
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• pp.309-317
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• 2002

A spectrofluorimetric method for the simultaneous determination of amino acids (tryptophan and tyrosine) based on the application of multivariate calibration method such as principal component regression and partial least squares (PLS) to luminescence measurements has been studied. Emission spectra of synthetic mixtures of two amino acids were obtained at excitation wavelength of 257 ㎚. The calibration model in PCR and PLS was obtained from the spectral data in the range of 280-500 ㎚ for each standard of a calibration set of 32 standards, each containing different amounts of two amino acids. The relative standard error of prediction ($RSEP_a$) was obtained to assess the model goodness in quantifying each analyte in a validation set. The overall relative standard error of prediction ($RSEP_m$) for the mixture obtained from the results of a validation set, formed by 6 independent mixtures was also used to validate the present method.