• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.885-892
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• 2012

Energy transfer dynamics of excited vibrational energy of OH stretching bonds in liquid water is theoretically studied. With time-dependent vibrational Hamiltonian obtained from a mixed quantum/classical calculation, we construct a master equation describing the energy transfer dynamics. Survival probability predicted by the master equation is compared with numerically exact one and we found that incoherent picture of energy transfer is reasonably valid for long-time population dynamics. Within the incoherent picture, we assess the validity of independent pair approximation (IPA) often introduced in the theoretical models utilized in the analysis of experimental data. Our results support that the IPA is almost perfectly valid as applied for the vibrational energy transfer in liquid water. However, proper incorporation of radial and orientational correlations between two OH bonds is found to be critical for a theory to be quantitatively valid. Consequently, it is suggested that the Forster model should be generalized by including the effects of the pair correlations in order to be applied for vibrational energy transfer in liquid water.

• 한국측량학회지
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• 제33권1호
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• pp.1-9
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• 2015

원격탐사영상의 기상조건과 계절에 따른 모의는 영상 전처리 단계 중 대기보정 알고리즘의 역방향 구현을 통해 수행될 수 있다. 본 연구는 상용 원격탐사영상처리 프로그램에서 제공되는 대기보정기능으로 보정된 Landsat영상을 특정기상조건이 고려된 대기보정 이전 상태로 모의하는 방법을 실험하였다. 실험에 적용한 방법은 Forster 알고리즘(1984)과 6S RTM (Radiative Transfer Model) 이고, 모의된 결과영상을 특정기상조건의 원영상과 비교하여 일치성을 분석하였다. 6S RTM을 적용한 결과가 Forster 알고리즘보다 일치성이 높았고, 결과연구대상지역 영상으로 모의영상을 제작한 결과, 원영상과의 평균 RMSE of DN difference가 9.35이고, 평균 $R^2$는 0.7이였다. 결과적으로 참조 영상과 계절이 동일하고 시기가 유사한 모의영상 생성 시 실용적 활용 가능성을 입증하였다.

• 한국광학회지
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• 제2권4호
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• pp.203-208
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• 1991

모드동기된 아르곤 이온 레이저를 여기광원으로 사용한 시간상관 단일광자 계수장치를 이용하여 에틸렌글리콜 용매 내에서 Rhodamine 6G에서 Malachite Green으로의 비복사 에너지전달과정을 연구하였다. 측정된 donor의 형광소멸곡선을 full-fitting 방법으로 분석 처리하여 acceptor 농도의 변화에 따른 환산농도와 임계전이거리를 구했다. donor의 농도가 acceptor의 농도 보다 클때는 donor-donor의 원거리 쌍극자 모멘트에 의한 에너지 이주 효과를 고려해야하며 Forster 모델 보다 Huber 모델이 더 적절하였다.

• Bulletin of the Korean Chemical Society
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• 제17권7호
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• pp.616-621
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• 1996

The transfer of excitation energy from solvent to solute in polystyrene films doped with 2-(2'-hydroxyphenyl)benzothiazole (HBT) which undergoes intramolecular proton transfer in excited electronic state has been studied by employing steady state and time-resolved fluorescence measurements. The degree of Forster overlap between donor and acceptor molecule in this system is estimated to be moderate. Energy transfer efficiency increases with solute concentration at low concentration range and levels off at high concentration. It is observed that the excimer form of polystyrene is largely involved in energy transfer process. Photostability of HBT in polystyrene to UV light is also investigated to get insight into the long wavelength absorption band of HBT which was observed upon electron radiation.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.145-145
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• 2015

처음 유기물의 인광 발견 이후 Host-dopant 시스템을 이용하여 Emission layer(EML)을 Co-deopsition 하는 방법으로 주로 인광 유기 발광 다이오드를 제작 하였다. [1] co-deposition을 이용해 만든 유기 발광 다이오드에 많은 장점이 있지만, 반대로 소자를 제작하는데 있어서는 많은 문제점을 가지고 있다. [2-4] 이러한 문제점을 개선하기 위하여 co-deposition 대신 non-doped Multi Quantum Well(MQW) 구조를 사용하여 doping 하지 않는 방법을 이용하는 논문들이 보고 되고 있다. Hole, electron, exciton이 MQW 구조를 지나면서, dopant well 안에 갇히게 되고, 그 안에서 다른 layer 간에 energy transfer와, hole-electron leakage가 줄어 들어, 더 효율적인 유기 발광 다이오드를 만들 수 있게 된다. [5-7] 이 연구에서는 CBP를 Potential Barrier로 사용하고, Ir(ppy)3 (Green dopant), Ir(btp)2 (Red dopant) 를 각각 Potential Well로 사용하였고, 두께는 CBP 9nm, dopant 1nm로 하였다. 이러한 소자를 만들고 dopant를 3개의 well에 적당히 배치하여, 각 well에서의 실험적인 발광 량 과, EML 안에서의 발광 mechanism 그리고 각 potential barrier를 줄여가며 dexter, forster에 의한 energy transfer에 대하여 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제32권8호
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• pp.2599-2606
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• 2011

The fluorescence of ethidium bound to DNA, poly[d(A-T)$_2$], and poly[d(G-C)$_2$] at a [ethidium]/[DNA] ratio of 0.005 was quenched by porphyrins when both ethidium and the porphyrins simultaneously bound to the same polynucleotide. The quenching was tested using the "inner sphere" and the "Forster resonance energy transfer" (FRET) models, with the latter found to contribute, at least in part, to the quenching. Meso-tetrakis(N-methylpyridinium-4-yl)porphyrin (TMPyP) exhibited a higher quenching and FRET efficiency than cis-bis(N-methylpyridinium-4-yl)porphyrin (BMPyP) for all of the tested DNA and polynucleotides, demonstrating that energy transfer efficiency is affected by the number of positive charges of porphyrins.

• 한국재료학회지
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• 제6권12호
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• pp.1242-1247
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• 1996

Spatially fixed bichromophoric systems with nonidentical chromophores have been extensively employed for studies of electron transfer and excitation transfer. Excitation hopping behavior between two naphthy1 moieties on 7,14-dihydro-7,14-ethanodibenz[a,h] anthracene(DEA)has been explored by the time-resolved fluorescence anisotropy measurements. The experimentally obtained value of the hopping rate in DEA agrees at least qualitatively with that calculated on the basis of the Dexter's theory, but disagrees with that calculated on the basis of the Forster's theory, indicates that for a pair of donor and acceptor with inter-chromophore separation as short as 4.5 $\AA$, excitation transfer via electron exchange is a predominant process.

• 한국전기전자재료학회논문지
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• 제26권3호
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• pp.221-226
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• 2013

The water soluble quantum dots (QDs) are synthesized by the phase transfer and silica coating reaction. The photoluminescence intensity of silica-coated QDs are mainly affected by the amount of phase transfer agent, SDS (sodium dodecyl sulfate), and the maximum value is obtained at the cmc (critical micell concentration) concentration of SDS in the phase transfer reaction. Based on fluorescence spectra and field emission transmission electron microscope (FETEM), the energy transfer rate by forster resonance energy transfer (FRET) is increasing with the thickness of the silica shell coated on CdSe/ZnS QDs.

• KIEE International Transactions on Electrophysics and Applications
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• 제11C권3호
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• pp.53-57
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• 2001

The organic light-emitting devices (OLEDs) based on fluorescence have low efficiency due to the requirement of spin-symmetry conservation. By using the phosphorescent material, internal quantum efficiency can reach 100%, compared with 25% in the case of the fluorescent material. Thus, phosphorescent OLEDs have recently been extensively studied and shown higher internal quantum efficiency than the conventional OLEDs. In this study, we investigated the characteristics of the phosphorescent OLEDs with the green emitting phosphor, $Ir(ppy)_3$ (tris(2-phenylpyridine)iridium). The device with a structure of ITO/TPD$Ir(ppy)_3$ doped in BCP/BCP/$Alq_3$/Li:Al/Al was fabricated, and its electrical and optical characteristics were studied. By changing the doping concentration of $Ir(ppy)_3$, we fabricated several devices and investigated their characteristics.

• Journal of Photoscience
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• 제12권1호
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• pp.11-15
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• 2005

The mechanism of interaction of two drugs viz., amoxicillin and cloxacillin with bovine serum albumin has been investigated using fluorescence absorption and circular dichroism spectroscopy. The quenching mechanism of fluorescence of bovine serum albumin by amoxicillin and cloxacillin was discussed. The binding sites number n and apparent binding constant Kwere measured by fluorescence quenching method. The thermodynamic parameters obtained from data at different temperatures were calculated. The distance r between donor (bovine serum albumin) and acceptor (amoxicillin and cloxacillin) was obtained according to Forster theory of non-radiative energy transfer. The effect of common ions on binding constant was also investigated. The results of synchronous fluorescence spectra, UV-vis absorption spectra and circular dichroism of BSA in presence of amoxicillin and cloxacillin show that the conformation of bovine serum albumin changed