• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.7
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• pp.1031-1038
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• 2002

The pressure sensitive paint (PSP) has recently received a considerable attention in the fields of aerodynamics and fluid mechanics as a new revolutionary optical technique to measure pressure fields on a body surface. In this study, the feasibility and effectiveness of the PSP pressure field measurement technique have been investigated experimentally. Seven different PSP formulations including two porphyrins(PtOEP and PtTFPP) and four polymers(Polystyrene, cellulous acetate butyrate, GP-197 and Silicon-708) were tested to check the performance and characteristics of each combination. The static calibration of each PSP formulation was carried out in a constant-pressure chamber. The PSP technique was applied to an oblique impinging jet flow to measure variation of pressure field on the impinging plate at on oblique jet angle of ${\theta}=60^{\circ}$. Pressure field images were captured by an 12bit intensified CCD(ICCD, $1K{\times}1K$)camera. As a result, the dynamic response of PSP depends on the oxygen permeability of polymer and the photochemical interaction between luminophore and polymer as well as the reaction of luminophore itself. The reaction of luminophore was changed by employing different polymers. In conclusion, Among 7 PSP formulation tested, the combination of PtTFPP and cellulous acetate butyrate show the best performance. In addition, the detail pressure field of an oblique high-speed impinging jet was measured effectively using the PSP technique.

• Journal of the Korean Solar Energy Society
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• v.39 no.4
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• pp.25-39
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• 2019

Luminescent solar concentrator (LSC), consisting of luminophore included glass or substrate with edge-mounted photovoltaic cell, is semi-transparent, energy harvesting devices. The luminophore absorbs incident solar light and re-emit photons, while the waveguide plate allows re-emitted photons to reach edge or bottom mounted photovoltaic cells with reduced losses. If the area of LSC is much larger than that of photovoltaic cell, this system can effectively concentrate solar light. In order to improve the performance of LSC, new materials and optical structures have been suggested by many research groups. For decreasing re-abosprion losses, it is essential to minimize the overlap between absorption and photoluminescence solar spectrum of luminophoroe. Moreover, the combination of selective top reflector and reflective optical cavity structure significantly boosts the waveguide efficiency in the LSC. As a result of many efforts, commercially available LSCs have been demonstrated and verified in the outdoor. Also, it is expected to generate electricity in buildings by replacing conventional glass to LSCs.

• Ocean and Polar Research
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• v.35 no.3
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• pp.229-237
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• 2013

We measured two-dimensional (2-D) oxygen distribution in the surface sediment layer of intertidal sediment using a simple and inexpensive planar oxygen optode, which is based on a color ratiometric image approach. The recorded emission intensity of red color luminophore light significantly changed with oxygen concentration by $O_2$ quenching of platinum(II)octaethylporphyrin (PtOEP). The ratios between the intensity of red and green emissions with oxygen concentration variation demonstrated the Stern-Volmer relationship. The 2-D oxygen distribution image showed microtopographic structure, diffusivity boundary layer and burrow in surface sediment layer. The oxygen penetration depth (OPD) was about 2 mm and the one-dimensional vertical diffusive oxygen uptake (DOU) was 12.6 mmol $m^{-2}d^{-1}$ in the undisturbed surface sediment layer. However, those were enhanced near burrow by benthic fauna, and the OPD was two times deeper and DOU was increased by 34%. The simple and inexpensive oxygen planar optode has great application potential in the study of oxygen dynamics with high spatiotemporal resolution, in benthic boundary layers.

• Journal of Photoscience
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• v.11 no.1
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• pp.35-40
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• 2004

[Ru(2,2'-bipyridine)$_2$(4,4'-dicarboxy-2,2'-bipyridine)]$^{2+}$(RuBDc) is a very photostable probe that possesses favorable photophysical properties including long lifetime, high quantum yield, large Stokes' shift, and highly polarized emission. To evaluate the usefulness of this luminophore (RuBDc) for studying macromolecular dynamics, its intensity and anisotropy decays when conjugated to RNA bacteriophage MS2 were examined using frequency-domain fluorometry with a high-intensity, blue light-emitting diode (LED) as the modulated light source. The intensity decays were best fit by a sum of two exponentials, and the mean intensity decay time was 442.2 ns. The anisotropy decay data showed a single rotational correlation time (2334.9 ns), which is typical for a spherical molecule. The use of RuBDc enabled us to measure the rotational correlation time up to several microseconds. These results indicate that RuBDc can be useful for studying rotational diffusion of biological macromolecules.s.

• Journal of Aerospace System Engineering
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• v.2 no.3
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• pp.19-23
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• 2008

We have fabricated pressure sensitive paint films consisting of PtTFPP activators dispersed in fluorinated polymer matrix. This matrix material is unique in its composition and structure. We evaluated the oxygen quenching effects, and thus the pressure sensitivity, of the fabricated films in terms of various processing parameters. Based on the experimental results, we anticipate that a good but new pressure sensitive paint would be presented through further elaboration of the polymer compositions and optimization of the processing conditions.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.688-693
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• 2003

The PSP technique has been used to measure pressure distribution on a model surface quantitatively. The objective of this study is to develop PSP technique which can be applied to low-speed flows. Four different PSP formulations including two porphyrins (PtOEP and PtTFPP) and two polymers (Poly(TMSP) and RTV-118) were tested and the performance of each combination was checked. In the static calibration, the luminescent intensity of the PSP coatings was measured from 0kPa to 11kPa with 0.5, 1, 2kPa increments. Among 4 PSP formulations tested, the combination of PtOEP and RTV-118 shows the best performance. The PSP technique was applied to an oblique impinging jet to measure the pressure field distribution on the impinging plate.

• Journal of Photoscience
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• v.7 no.4
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• pp.155-159
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• 2000

[Ru(bpy)$_2$(dppz)]$^2$$^{+}$ (bpy = 2,2'-bipyridine, dppz = dipyrido[3,2-a:2',3'-c]phenazine)(RuBD), a long-lifetime metal-ligand complex displays photophysical properties including long lifetime, polarized emission, and very little background fluorescence. To further show the usefulness of this luminophore(RuBD) for probing nucleic acid dynamics, its intensity and anisotropy decays when bound to tRN $A^{val}$ were examined using frequency-domain fluorometry with a blue light-emitting diode(LED)as the modulated light source. Unexpectedly much longer mean lifetime was obtained at 4$^{\circ}C$(<$\tau$>=178.3 ns) as compared to at $25^{\circ}C$(<$\tau$>=117.0 ns), suggesting more favorable conformation of tRN $A^{val}$ for RuBD when intercalated at 4$^{\circ}C$. The anisotropy decay data showed longer rotational correlation times at 4$^{\circ}C$(52.7 and 13.0 ns) than at $25^{\circ}C$ (32.9 and 10.3 ns). The presence of two rotational correlation times suggests that RuBD reveals both local and overall rotational motion of tRN $A^{val}$. Due to long lifetime of RuBD and small size of tRN $A^{val}$, very low steady-state anisotropy values were observed, 0.048 and 0.036 at 4 and $25^{\circ}C$, respectively. However, a clear difference in the modulated anisotropy values was seen between 4 and $25^{\circ}C$. These results indicate that RuBD can be useful for studying hydrodynamics of small nucleic acids such as tRN $A^{val}$.^{val}$.>.$.>.

• BMB Reports
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• v.38 no.1
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• pp.104-110
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• 2005

We extended the measurable time scale of DNA dynamics to microsecond using $[Ru(phen)_2(dppz)]^{2+}$ (phen = 1,10-phenanthroline, dppz = dipyrido[3,2-a:2',3'-c]phenazine) (RuPD), which displays a mean lifetime near 500 ns. To evaluate the usefulness of this luminophore (RuPD) for probing nucleic acid dynamics, its intensity and anisotropy decays when intercalated into supercoiled and linear pBluescript (pBS) II SK(+) phagemids were examined using frequency-domain fluorometry with a blue light-emitting diode (LED) as the modulated light source. The mean lifetime for the supercoiled phagemids (< $\tau$ > = 489.7 ns) was somewhat shorter than that for the linear phagemids (< $\tau$ > = 506.4 ns), suggesting a more efficient shielding from water by the linear phagemids. The anisotropy decay data also showed somewhat shorter slow rotational correlation times for supercoiled phagemids (997.2 ns) than for the linear phagemids (1175.6 ns). The slow and fast rotational correlation times appear to be consistent with the bending and torsional motions of the phagemids, respectively. These results indicate that RuPD can have applications in studies of both bending and torsional dynamics of nucleic acids.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.4
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• pp.12-17
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• 2004

The PSP technique has been used to measure pressure distribution on model surfaces ins high-speed flows. The objective of this study is to develop a PSP technique which can be applied to low-speed aerodynamic flows. Four different PSP formulations including two porphyrins (PtOEP and PtTFPP) and two polymers (Poly(TMSP) and RTV-118) were tested and the performance of each combination was evaluated. In a static calibration, the luminescent intensity of the PSP coatings was measured from 0kPa to 11kPa with 0.5, 1, 2kPa increments. Among 4 PSP formulations tested, the combination of PtOEP and RTV-118 shows the best performance. The developed PSP technique was applied to an oblique impinging jet to measure the pressure field distribution on the impinging plate.

• BMB Reports
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• v.35 no.4
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• pp.389-394
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• 2002

$[Ru(bpy)_2(dppz)]^2+$ (bpy=2,2'-bipyfidine, dppz=dipyrido[3,2-a:2',3'-c]phenazine) (RuBD), a long-lifetime metal-ligand complex, displays favorable photophysical properties. These include long lifetime, polarized emission, but no significant fluorescence from the complex that is not bound to DNA. To show the usefulness of this luminophore (RuBD) for probing the bending and torsional dynamics of nucleic acids, its intensity and anisotropy decays when intercalated into supercoiled and relaxed pTZ18U plasmids were examined using frequency-domain fluorometry with a blue light-emitting diode (LED) as the modulated light source. The mean lifetimes for the supercoiled plasmids (< $\tau$ >=148 ns) were somewhat shorter than those for the relaxed plasmids (< $\tau$ >=160 ns). This suggests that the relaxed plasmids were shielded more efficiently from water. The anisotropy decay data also showed somewhat shorter slow rotational correlation times for supercoiled plasmids (288 ns) than for the relaxed plasmids (355 ns). The presence of two rotational correlation times suggests that RuBD reveals both the bending and torsional motions of the plasmids. These results indicate that RuBD can be useful for studying both the bending and torsional dynamics of mucleic acids.