• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.1
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• pp.1-9
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• 2003

To evaluate the quantitative nature of laser fluorescence(LF) and dye-enhanced laser fluorescence(DELF) on early enamel caries, artificial caries were induced on the bovine enamels and argon laser was irradiated on the surfaces of lesions. Fluorescence radiance from enamel specimen was recorded with CCD camera which was connected to PC image analyzing system. The difference of fluorescence of radiance(DFR) between the carious and the sound enamel in each sample of the LF and the DELF groups were measured by image analyzing program. The DFR of lesion surfaces measured with laser fluorescence and lesion depths were evaluated and the results are as follows: The caries lesions were discriminated from sound enamels by the darkness with LF and by the brightness with DELF. The DELF was more sensitive than the LF at the earlier stage of demineralization.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.3
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• pp.261-266
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• 2019

Flow cytometry is an electrical detection system that provides precise and diverse optical properties to cells and micro particles. Flow cytometry, which provides multidimensional information including cell size and granularity through light scattering and fluorescence emission generated by the induction of light of a specific wavelength to the fluorescently treated cells or micro particles, plays an important role in biomedical and biophysical fields. However, it has some drawbacks such as high cost, size of the instrument and limitation in selecting fluorescent dyes. Therefore, in this paper, a low cost compact fluorescent detection system is developed using light-emitting diode and microcontroller. The proposed fluorescence detection system has a replaceable the light source/fluorescence filter/photodetector and constructed by 3D printer, so that the user can design a customized system according to the selected fluorescent dyes. The fluorescence intensity was measured by varying the number of fluorescently labeled cells, and the measured intensities showed a high linearity within the tested concentration ranges.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.2
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• pp.236-246
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• 2004

Artificial carious lesions in various depths were observed with visual examination using light transillumination, bite-wing radiography, laser fluorescence, and dye-enhanced laser fluorescence to determine the reproducibility, correlation of each diagnostic method, diagnostic sensitivity and diagnostic specificity. And optical densities according to demineralized times were measured whether laser fluorescence could be used as a quantitative diagnostic method. The following results were obtained whether laser fluorescence could be used for diagnosis of initial proximal caries. 1. Tau-c values of visual examination was 0.08 which showed lowest reproducibility and those of bite-wing radiography, laser fluorescence, dye-enhanced laser fluorescence were 0.60, 0.48, and 0.64, respectively which showed relatively high reproducibility. 2. The correlation between demineralization time and each examination was the highest in dye-enhanced laser fluorescence$({\gamma}=0.51)$ followed by laser fluorescence$({\gamma}=0.43)$, bite-wing radiograph$({\gamma}=0.35)$, and visual examination$({\gamma}=0.33)$. Dye-enhanced laser fluorescence and laser fluorescence showed significant correlation with demineralization time. 3. The sensitivity of laser fluorescence and dye-enhanced laser fluorescence for diagnosing approximal caries based on bite-wing radiography were 67%, 100% and those of specificity were 57%, 11% which showed diagnostic specificity was relatively lower than sensitivity. 4. The difference in optical density(DFR) between sound teeth and carious lesions according to lesion depth was high with dye-enhanced laser fluorescence compared with laser fluorescence. DFR measured with laser fluorescence according to changes in lesion depth was statistically significant but was not statistically significant with dye-enhanced laser fluorescence. Based on these results, laser fluorescence and dye-enhanced laser fluorescence have comparable diagnostic power as bite-wing radiography in early diagnosis of proximal caries.

• Proceedings of the Optical Society of Korea Conference
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• 2004.07a
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• pp.296-297
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• 2004

시분할 형광 분석법은 발광하는 형광을 통해 시료내의 미량의 물질을 분석 할 수 있는 분석법으로 생화학, 면역학 등 여러 분야에서 응용되고 있으며 새로운 응용 분야에 대한 연구가 활발하게 진행되고 있다. 본 연구에서는 유러피엄(Europium) 화합물을 면역학적 검출기로 사용한 측방유동 시료(lateral flow assay)를 시분할 형광 분석법으로 측정한 결과를 소개한다.

• Applied Chemistry for Engineering
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• v.33 no.5
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• pp.451-458
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• 2022

Semiconductor quantum dots (QDs) are optical probes with excellent fluorescence properties. Therefore, they have been applied to various bio-medical imaging techniques and biosensors. Due to the unique optical characteristics of wide absorption and narrow fluorescence energy bands, multiple types of signals can be generated by the combination of fluorescence wavelengths from different QDs, which enables the simultaneous detection of more than two biomarkers. In this review, the advantages and applications of QDs and QD nanobeads (QBs) in multiple biomarker assays were described, and new developments or improvements in multiplexed biomarker detection techniques were summarized. In particular, recent reports were summarized, focusing on the design strategies in immunoassay construction and signal transducing materials for fluorescence-linked immunosorbent assays using QDs and immunochromatographic assays using QBs. New detection platforms will be developed for early diagnosis of diseases and other fields if multiplexed detection technologies of excellent accuracy and sensitivity are combined with artificial intelligence algorithms.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.45.1-45.1
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• 2009

본 연구에서는 BaSrFBr:Eu 형광물질의 결함 농도 분석을 시도하였다. 또한 동시 계수 방법과 Fast -Slow - Coincidence 시스템으로 구성한 양전자 수명 측정법을 통하여 에너지의 변화에 따른 양성자 조사에 의한 시료 결함에 따른 동시 계수 도플러법과 양전자 수명의 변화를 측정 하였으며, SRIM 시뮬레이션을 통한 에너지에 따른 양성자 투과 깊이의 변화를 연구하였다.

• Journal of the Korean Ceramic Society
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• v.33 no.8
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• pp.928-934
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• 1996

Quantitative analysis each portland cement components was conducted by standard calibration method using X-ray fluorescence spectrometer. Standard sample and the unknown sample were prepared by fused cast bead method. In checking the errors of standard cement 227A372 the relative errors of constituents such as CaO, SiO2, Al2O3, Fe2O3, MgO and SrO were less than 1% and the relative errors of constituents such as So3, K2O, TiO2, Na2O P2O5, and Mn2O3 were less than 5% Sample preparation was mainly contributed to the errors. Compared with general wet chemical method the results of X-ray fluorescence analyses were more precise and accurate. Moreover it is possible to analyze precisely a little amount of the constituents such as SrO, Mn2O3 and P2O5 the analyses of which were very difficult using the wet chemical method.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.9
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• pp.940-948
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• 2006

Fluorescence measurements of dissolved organic matter(DOM) have the superior advantages over other analysis tools for applying to water quality management. They are simple and fast and require minimal pretreatment of samples. Fluorescence index($F_{450}/F_{500}$), synchronous spectra, and fluorescence excitation-emission matrices(EEM) of various DOM samples were investigated to discriminate autochthonous/allochthonous composition, protein-like fluorescence, fulvic-like fluorescence, humic-like fluorescence, terestrial humic-like fluorescence by comparing among the real DOM samples of different origins with the help of literature. The samples used included standard purified DOM, lake, river and wastewater treatment effluent. The relative distribution of various DOM composition was derived from the ratios of each fluorescence region. The results were very consistent with those expected from the sample properties. Allochthonous and terrestrial humic-like fluorescence were more prominent in the samples with abundant soil-derived DOM components. In addition, the protein-like fluorescence property was more pronounced in the samples where strong algal or microbial activities were expected. It was also shown that the ratio of protein-like/terrestrial humic-like fluorescence obtained from synchronous spectrum and fluorescence EEM could be used as an indicator for the evaluation of wastewater treatment on the downstream water quality of rivers and for the prediction of the degree of algal/microbial activities in lakes. It is expected that the results of this study will provide the basic information to develop the future water quality management techniques using DOM fluorescence measurements.

• Journal of the Korean Ceramic Society
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• v.37 no.9
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• pp.927-932
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• 2000

Mg(NO$_3$)$_2$가 용해된 IPA 용액에서 형광 분말의 전기영동법에 의한 증착 과정을 증착 시간, Mg(NO$_3$)$_2$의 농도 및 열처리 조건에 따라 분석하였다. 전기영동법으로 가장 두께가 균일한 형광막을 얻기 위한 Mg(NO$_3$)$_2$의 최적 농도는 $10^{-3}$~$10^{-4}$ M였다. 형광체의 접착력을 향상시키기 위해 새로운 방법을 고안하였다. 즉 전기영동법으로 증착된 형광막에 B$_2$O$_3$가 용해된 IPA 용액을 분사한 후 열처리를 하였다. 그 결과 기존의 PL 특성을 그대로 유지하면서 접착력을 향상시킬 수 있었다. 그러나 CL 휘도는 약간 감소하였다.

• Analytical Science and Technology
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• v.8 no.1
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• pp.41-45
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• 1995

To analyze mixed rare earth elements quantitatively a nonlinear fitting method was applied to laser induced fluorescence signals. Mixed flourescence signal of two elements, Sm and Eu were resolved independently and determined the concentration of these two elements simultaneously. It was found that detection limit for each element in the mixture was sub-ppb level which was the same as that of the single element sample. Additionally it was found that lifetimes of Sm and Eu extracted from the nonlinear fitting method is the same as in the single element cases.