• Bulletin of the Korean Chemical Society
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• 제32권3호
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• pp.905-908
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• 2011

We report fluorescence excitation and emission spectra of the CHBr molecule generated via pyrolysis of $CH_3Br$ in a molecular beam experiment. The 193 nm attenuation cross sections were estimated from the reduction of the CHBr signal as a function of the excimer laser fluence. The derived 193 nm absorption cross section for CHBr [$(3.24{\pm}0.59){\times}10^{-17}\;cm^2$] is slightly higher than the absorption cross section previously determined for CHCl [$(2.6{\pm}0.8){\times}10^{-17}\;cm^2$], but the difference is within the estimated uncertainties in the measured cross section.

• Bulletin of the Korean Chemical Society
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• 제30권5호
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• pp.1093-1096
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• 2009

Two new chemosensors 1 and 2 derived from 5,12- and 5,7-dioxocyclams were prepared and their signaling behaviors toward transition metal ions were investigated. Chemosensors 1 and 2 showed very efficient responses toward $Cu_{2+}$ and $Hg_{2+}$ ions. Ratiometric analysis of the fluorescence changes in pyrene monomer and excimer emissions clearly demonstrated the $Cu_{2+}$- and $Hg_{2+}$-selective signaling behavior. The signaling mechanism of the chemosensors is due to conformation changes upon complexation with metal ions and the inherent quenching nature of the complexed $Cu_{2+}$ and $Hg_{2+}$ ions themselves.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2001년도 춘계학술대회 논문집
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• pp.75-90
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• 2001

For the purpose of helping development of a GDI(Gasoline Direct Injection) engine, the in-cylinder phenomena, such as the spray behaviors and fuel distributions, unburned fuel, and flame characteristics were investigated in a single cylinder GDI engine. The GDI engine was equipped with a swirl type electronic injector and SCV(Swirl Control Valve). PLIF(Planar Laser Induced Fluorescence) system with KrF Excimer laser was used for the measurements of the fuel distributions. The effects of the injector specifications, such as the spray cone angle and the offset angle on the fuel distributions and combustion characteristics were investigated. As a result, it was found that the injected fuel spray collided with the bottom of the bowl and moved upward along the exhaust side wall of the piston bowl. This fuel vapor played a important role in the instance of spark ignition. The injector specifications has a great influence on the flame characteristics.

• 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.

• Bulletin of the Korean Chemical Society
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• 제21권3호
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• pp.321-327
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• 2000

Polynucleotide analogues containing pyrimidine (uracil and thynime) bases, $poly[(1'{\beta}-uracil-1-yl-2'.5'-dideoxy-D-glycero-pent-4'-enofuranose)-alt-(maleic$ acid)] (12) and $poly[(1'-{\beta}-thymin-1-yl-2'5'-dideoxy-D-glycero-pent-4'-enofuranose)-alt-(maleic$, acid)] (15), were synthesized by the altermating copolymerization of relevant nucleosied derivatives and maleic anhydride, and the subsequent hydrolysis. The polymers had quite similar structures to the natural polymes and were soluble in water, They showed high hypochromicities up to 49% and excimer fluorescence due to the base stacking, and polyelectrolyte behavior. Since the polymers had compact structrures, depyrimidinations, the release of pyrimidine bases from the polymer backbone, occurred in aqueous solutions with higher rates compared with those of the natural polymers.

• 대한약리학회지
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• 제29권1호
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• pp.157-163
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• 1993

n-Alkanols의 분자적 약리작용기전 탐구에 기초자료를 제공하기 위하여 소의 신선한 대뇌피질로부터 분리한 synaptosomal plasma membrane vesicles (SPMV) 지질 이중층의 측방확산운동에 미치는 n-alkanols의 영향을 형광 probe법으로 검색하였다. n-Alkanols는 SPMV 지질 이중층의 측방확산운동 범위와 속도를 농도 의존적으로 증가시켰고 1-nonanol까지는 탄소수가 두개 증가될 때마다 그 효력은 약 10배 가량 증가되었으나 탄소수 10개인 1-decanol의 효력은 오히려 감소되는 경향을 나타내었다.

• 대한화장품학회지
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• 제10권1호
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• pp.13-23
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• 1984

The fluorescence intensity rations (F2.F1) of excimer (F2) to monomer (F1) of pyrene were measured as a function of the concentration of sodium dodecyl sulfate (SDS). It was found that there were not gross changes in size and shape of sphere-shape micelles in the first micelle concentration, while at concentrations above the second critical micelle concentration (CMC) the micelles grew in size with increasing concentration. Fluorescence intensities of 8-anilinonaphthalene 1-sulfonate (ANS) were also monitored as a micellar probe with varying concentrations of SDS. Results suggested that a phase transition from sphere-shaped micelles to hemicapped rod-like micelles occurred at the second CMC (17). A general formula for the axial ratio of ellip-soil-shaped micelle in the first micelle concentration was suggested. According to this general formula, the axial ratio of SDS, sodium lauryl ether sulfate and sodium laurate were 1:1, 5:2, and 5:3, respectively. The electrolyte-induced phase transition from spherical to hemicapped rod-like micelles occurred and the size of hemicapped rod-like micelles grew with increasing electrolyte concentrations. The maximum concentrations of solubilzed benzene in sphere-shaped micelles and hemicapped rod-like micelles were measured by differential spectrohpotometry. The hemicapped rod-like micelles in the presence of electrolytes grew in size with increasing amount of benzene solubilized.

• 한국분무공학회지
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• 제4권2호
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• pp.19-32
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• 1999

The present study investigated the forms and behaviors of fuel during intake and compression process, and the initial flame stability in a lean burn engine modified as a single cylinder engine equipped with quartz windows for visualization. PLIF(Planar Laser Induced Fluorescence) method with KrF Excimer laser was used for measuring the fuel distributions. The principal design concept of the lean burn nin in this study is the axial stratification in the fuel distribution via fuel injection during intake process and different shapes of intake ports; helical and straight. The experiments showed that fuel flowed in as a vapor state in the early part of intake process and lots of this mixture mated down along the intake valve side cylinder wall, but in the latter part, a lot of fuel flowed in as a liquid state and this fuel stayed in the upper part of cylinder, after that the dense fuel cloud moved upward in the early of part compression process. It became clear that the fuel flowed in via straight port had a important role in the axial fuel stratification.

• 한국수소및신에너지학회논문집
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• 제13권4호
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• pp.279-286
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• 2002

In this study, quantitative nitric oxide concentration distributions are investigated in the laminar non-premixed $H_2/N_2$ flames by laser-induced fluorescence (LIF). The measurements are taken in flames for different $N_2$ dilution ratios varying from 20~80%, and fuel flow rate is fixed as Islpm. The NO A-X (0,0) vibrational band around 226 nm is excited using a XeCl excimer-pumped dye laser. We applied same excitation line used in $CH_4$, premixed flame. Overall, NO concentration was rapidly decreased with Na addition and we could not measure the concentration any longer for $N_2$ dilution above 80%.

• 에너지공학
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• 제10권4호
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• pp.379-386
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• 2001

본 연구는 산업용 고부하 버너연소에서의 NO$_{x}$ 저감에 관한 실험적 연구이다. 본 연구에서는 NO$_{x}$의 정량적 농도 분포 측정을 위하여 레이저 유동 형광법을 사용하였다. XeCL 엑시머 레이저를 사용하여 NO A-X (0, 0) 진동밴드를 226 nm로 여기하였다. 또한 P$_{21}$+Q$_1$(14.5)/R$_{12}$+Q$_2$(20.5)/P$_1$(23.5) 전이를 여기라인으로 하였으며 다른 간섭의 영향을 최소화 하였다. 본 실험에서 이중선회 확산화염에서의 NO 농도 분포를 측정하였으며, 이 스월버너에서의 화염의 후류에 있어서 NO 농도는 1차/2차 공기비가 증가할 때 감소함을 알수 있었다.