• Bulletin of the Korean Chemical Society
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• v.7 no.6
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• pp.458-461
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• 1986

The fluorescence intensity of khellin-dimethylfumarate C$_4$-cycloadduct (KDF) is very sensitive to temperature and to the nature of solvents, especially hydrogen-bonding ability. The fluorescence quantum yields of KDF in ethanol and isopentane at 77K are 0.73 and 0.54, respectively, both of which are much larger than the room temperature values. The phosphorescence lifetime is very long and decreases with decreasing the solvent polarity. The phosphorescence and fluorescence quantum yield ratio is very small and decreases with decreasing solvent polarity. The solvent relaxation plays an important role in the excited states of KDF. The internal conversion is a major decay process of the excited singlet state of KDF in all the solvents used at room temperature.

• Bulletin of the Korean Chemical Society
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• v.13 no.6
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• pp.650-654
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• 1992

Absorption and fluorescence spectra are reported for four different 1 : 3 $Dy^{3+}$ : ligand systems in aqueous solution under mild alkaline pH conditions. The ligands included in this study are oxidiacetate, dipicolinate, iminodiacetate and methyliminodiacetate. The oscillator strengths for the 4f→4f multiplet-to-multiplet transitions are empirically determined from the absorption spectra and the intensity parameters ${\Omega}_{\lambda}$}(${\lambda}$ = 2, 4, 6) for the systems are also obtained by applying the Judd-Ofelt theorem to the observed oscillator strengths. The values of the intensity parameters for the systems are compared and discussed in terms of ligand structural properties to investigate how the intensity parameters can response to the minor changes in the ligand environment. In addition, the relative oscillator strengths for fluorescence are evaluated and compared to the results obtained from absorption spectra.

• Bulletin of the Korean Chemical Society
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• v.8 no.4
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• pp.341-344
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• 1987

The fluorescence quantum yield of khellin is sensitive to temperature and to the nature of solvents, especially the proton-donating ability in solute-to-solvent hydrogen bonding. The intersystem crossing quantum yields are 0.4 and 0.15 in acetonitrile and ethanol, respectively. The fluorescence quantum yields in ethanol and isopentane at 77 K are 0.61 and 0.07, respectively, both of which are much larger than the values at room temperature. The phosphorescence lifetime is relatively long and decreases with decreasing solvent polarity. The phosphorescence to fluorescence quantum yield ratio is very small and remains unchanged in various solvents. The results suggest that internal conversion is an important decay channel of the excited singlet state of khellin, especially in the hydrogen-bonding hydroxyl solvents.

• Journal of Photoscience
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• v.9 no.2
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• pp.70-73
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• 2002

A cyanobacteria-like organism Aaryochloris marina performs oxygenic photosynthesis with near far-red light by the use of chlorophyll d. Reaction center chlorophyll (Chl) of Photosystem (PS) II of A. marina was studied by analysis of millisecond-delayed fluorescence. Delayed fluorescence is emitted by Chi d indicating efficient energy transfer between antenna Chi d molecules and the unknown primary electron donor of PS II. P740 a reaction center Chl of PS I of A. marina is shown to give a dimer type cation, and triplet state with a D value of 245xlO$\^$-4/ cm$\^$-l/ in contrast to the 280-290 xlO$\^$-4/cm$\^$-l/ values of P700 suggesting triplet spins interacting at a 5% larger distance in P740 than in P700.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.1
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• pp.93-101
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• 2000

The characteristics of spray nozzle have been quantified with the measurement of fluorescence and Mie scattering images. To correct the attenuation of the incident light sheet, a sequential double-pass light sheet system and the geometrical averaging of two images was implemented. Quantitative mass flux distribution of spray was obtained from fluorescence image. 3-D image is reconstructed using 2-D radial images. Sauter mean diameter (SMD) distribution was determined using the ratio of fluorescence signal intensity and Mie scattering signal intensity and the values were quantified with PDP A data. The measurement of mass flux and SMD using planar imaging technique agee with PDP A data fairly well in the low density region. However, in dense region， there are significant errors caused by secondary scattering. It was found that the planar imaging technique provides many advantages over the point measurement technique, such as PDP A, and can be implemented for quantitative measurement, especially in low density region.

• Bulletin of the Korean Chemical Society
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• v.13 no.1
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• pp.54-59
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• 1992

Spectroscopic measurements and theoretical calculations are performed for the four 1 : 3 Sm(III) : ligand solutions. The ligands included in this study are oxidiacetate, iminodiacetate, methyliminodiacetate and dipicolinate. The oscillator strengths for the $4f{\to}4f$ multiplet-to-multiplet transitions are empirically determined from the absorption spectra. The intensity parameters ${\Omega}_{\lambda}\;({\lambda}=2,\;4,\;6)$ of $Sm^{3+}$(aquo) and ${SmL_3}^{3-}$ complexes are also evaluated by applying the Judd-Ofelt theorem to the observed oscillator strengths. The values of the intensity parameters are compared and discussed in term of structural properties of the complexes. In addition, the fluorescence spectra are reported for the Sm(III) complex systems under mild alkaline condition. The excitation from the $^6H_{5/2}$ ground state to any excited states lying above the emitting energy level $(^4G_{5/2})$ produces four fluorescence bands, following nonradiative transitions from a certain excited state to the $^4G_{5/2}$ state. The ratios of oscillator strengths of ${SmL_3}^{3-}$ complexes to that of $Sm^{3+}$(aquo) are also evaluated from the fluorescence spectra and compared to the results obtained from the absorption bands.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.08a
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• pp.67-67
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• 2020

Though there is an on-going need for the diversity of ornamental plants for in-door environment, their growth and stress adaptability in comparatively low light intensity condition require further studies for implementation. Here investigates the growth and chlorophyll fluorescence parameters of Farfugium japonicum (L.) Kitam, Liriope muscari (Decne.) L.H.Bailey and Acorus gramineus Aiton under several light intensities which were based on common in-door environment. The growth measurement of the plants included the quantity, length, width and SPAD value of the leaves. Calculated values of Fm/Fo, Fv/Fm, Pi_Abs, ETo/RC and DIo/RC were used as the parameters of the chlorophyll fluorescence under 10, 50, 100 and 200 PPFD (μmol·m^-2·s^-1) light intensities. In-door plants group was put in a closed room allowing no other light sources for 10 weeks and the control group was put in glass-greenhouse for the same period. The overall in-door growth of L. muscari was not significantly different in all light intensities compared to the control group and even showed the higher SPAD values. Also, an increasing tendency of Pi_Abs value under 10 to 100 PPFD was observed implying that L.muscari could adapt well to in-door environment. Measurement of A. gramineus growth mostly showed the highest values in the control group especially in the number of the leaves. Nevertheless, chlorophyll fluorescence parameters showed no significant value difference between in-door and the control groups and thus, A. gramineus might have possibility of successful adaptation to in-door environment. F. japonicum showed deficient growth in plant height and leaf length compared to the control but, it seemed to be able to sustain ornamental value under in-door light intensities. Furthermore, Pi_Abs and DIo/RC values were increased under in-door light conditions suggesting potential adaptability of F. japonicum.

• Journal of the Korean Applied Science and Technology
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• v.33 no.1
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• pp.136-142
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• 2016

The influences of fluorescence, scattering, and flocculation in random media were interpreted for the scattered fluorescence intensity and wavelength, it has been studied the molecular properties by the spectroscopy of laser induced fluorescence(LIF). The effects of optical properties in scattering media have been found by the optical parameters(${\mu}_s$, ${\mu}_a$, ${\mu}_t$). Flocculation is an important step in many solid-liquid separation processes and is widely used in Photodynamic therapy. The interactions of several colloid particles can come into play which have major effect on the flocculation and LIF process. We measured scattering and fluorescence spectra of the sample in vitro as function of distance from lase source to detector. The value of scattering coefficient ${\mu}_s$ is and ${\beta}$-carotene were measured as larger values(I, ${\delta}$) by means of closer distance from source to detector.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.2
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• pp.77-84
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• 2022

This study aimed to evaluate the growth, yield, and grain quality characteristics of rice varieties that were subjected to water stress during the tillering stage. We also sought to identify whether water stress could be indicated via the plants' response to chlorophyll fluorescence. In this study, we induced water stress by intentionally cutting off water for 30 days, starting 15 days after transplanting the rice varieties to a greenhouse. We analyzed nine rice varieties, including Ilpum, which is the most frequently cultivated variety in Gyeongsangbuk-do, South Korea. The control group was planted in a paddy field where irrigation was entirely dependent on rainfall. Our results revealed that the heading stage of the nine studied varieties occurred approximately ten days earlier in the rain shelter than in the field. Moreover, the rice yield, head rice rate, and palatability score decreased by 18.6%, 17.1%, and 8.3%, respectively, while protein content increased by 20.2% compared with the control group. The Saenuri and Haimi varieties showed the lowest reduction in yield under the water stress conditions, while the Daebo and Samkwang varieties showed the highest reduction in yield. The chlorophyll fluorescence response after re-irrigation was measured between July 30^th and August 17^th. The ratio of variable fluorescence to maximum chlorophyll fluorescence (F_V/F_M) values failed to recover to their baseline values, resulting in either no change or a reduction in fluorescent response, even after re-irrigation of Daebo and Samkwang varieties. These results can be utilized as empirical data for drought-affected farms to select resistant varieties that can respond to spring drought in the southern plains of Gyeongsangbuk-do.

• 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.