• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2253-2260
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• 2007

A series of tetra donor substituted [2.2]paracyclophane-based two-photon absorption (TPA) fluorophores were synthesized in neutral and cationic forms. The imaging activity of overall set of fluorophores was studied by the two-photon induced fluorescence (TPIF) method in a range of solvents. We also measured a clear progression toward a longer photoluminescence lifetime with increasing solvent polarity (intrinsic photoluminescence lifetime, τi: ~2 ns in toluene → 12-16 ns in water). The paracyclophane fluorophores with this unique property can be utilized as an optical polarity probe for the biomolecular substrates. The combined measurement of the two-photon fluorescence microscopy (TPM) cell image and TPIF lifetime can give us a better understanding of the biological processes and local environments in the cells.

• Journal of Information Display
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• v.7 no.4
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• pp.24-26
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• 2006

We have developed a new driving method named TROPHY(Talented Role-playing Technology with Dual Polarity sustainer in Hybrid Mono board). In this method, the sustain voltage is partially compared to the conventional method and the number of power sources is reduced by voltage level unification during the reset, address and sustain period. The hybrid mono board was especially developed to implement those technologies. Through this, we can lower the cost with the TROPHY compared to the conventional one. It is a suitable technology to improve the reliability of circuit and image sticking problem. We can also reduce the number of driving boards and the EMI problem compared with those of the conventional method.

• Journal of Photoscience
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• v.6 no.2
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• pp.61-65
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• 1999

The fluorescence properties and photoisomerization behavior of 1-(9-anthryl)-2-(n-quinolinyl)ethene (n-AQE, n=2-4) have been investigated in various solvents. t-3-AQE is strongly fluorescent, but does not accomplish photoisomerization, similar to parent hydrocarbon compound, t-1-(9-anthryl)-2-phenylethene (t-9-APE) or t-1-(9-anthryl)-2-(1-naphthyl)ethene (t-1-ANE). Fluorescence and photoisomerization oft-2-AQE and t-4-AQE are strongly affected by solvent polarity. Dependence of fluorescence quantum yield on the solvent polarity is moderate for t-2-AQE and large for t-4-AQE. In nonpolar solvent (in n-hexane), they exhibit relatively strong fluorescence, but do not isomerize to cis isomer on irradiation, even if inefficient isomerization is observed for t-4-AQE. However, as solvent polarity increases, their fluorescences become weak with efficient photoisomerization to corresponding cis isomer. Intramolecular charge-transfer excited state is presumed to contribute to photoisomerization. The S$_1$ decay parameters were found to be solvent-dependent due to the charge-transfer character of lowest S$_1$ state. In polar solvents, the activation barrier to twisting is reduced enhancing the isomerization of r-2-AQE and t-4-AQE in the singlet manifold.

• Journal of Photoscience
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• v.6 no.4
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• pp.171-176
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• 1999

The spectral and photophysical properties of trans-1-pyrazinyl-2-(3-quinolinyl)ethylene (trans-3- PyQE) are investigated under various conditions in order to obtain information on ground and excited states. The absorption spectrum of trans-3-PyQE changes slightly with varying degree of solvent polarity ; the. fluorescence spectrum is shifted to the red and becomes broad and structureless as the solvent polarity increases. The fluorescence quantum yield increases with increasing solvent polarity. The fluorescence intensity of trans-3-PyQE decreases as the concentration of methyl iodide increases. The fluorescence spectra of trans-3-PyQE changes markedly upon the variation of the excitation wavelength, presumably due to an equilibrium between conformers originating from the rotation of a quasi-single bond between the quinolinyl group and ethylenic carbon atom. These results indicate that the spectral and photophysical properties of trans-3-PyQE are strongly influenced by solvent, heavy atom, and an equilibrium between conformers

• Journal of the Korean Magnetic Resonance Society
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• v.4 no.2
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• pp.91-102
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• 2000

The photoproduced cation radical of N-methylphenothiazine doped in the different kind of matrices of phenyltriethoxysilane (PhiTEOS), vinyltriethoxysilane (VTEOS), and methyloiethoxysilane (METOS) was comparatively studied with electron spin resonance (ESR) and electron nuclear double resonance (ENDOR). The photoinduced charge separation efficiency was determined by integration of ESR spectra which correspond to the amount of photoproduced cation radical in the matrices. This was correlatively studied with the polarity and pore size of the gel matrices. The polarity of the matrices was comparatively determined by measuring λ$\sub$max/ values of PC$_1$ in the different matrices. The relative pore size among the matrices was determined by measuring relative proton matrix ENDOR line widths of the photoproduced cation radical of PCI. The decay kinetic constants of the cation radical of PCI in the different matrices was relatively studied with fitting the biexponential decay curves after exposure into the ambient condition. This is correlatively interpreted with the polarity and pore size of the matrices.

• Journal of Power Electronics
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• v.2 no.3
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• pp.189-198
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• 2002

New concept of energy recovery for plasma display panel (PDP) Is proposed. Different from conventional LC resonant sustaining drivers, the current built up before inverting the polarity of the panel electrodes is utilized to change the panel Polarity together with energy Previously charged in Panel capacitance. This operation Provides zero -voltage-switching of switches and reduction of EMI by rejecting the surge current when the sustain switches are turned on. The build-up current helps to reduce transition time of panel polarity and may produce more stable light waveforms. This method shows a desirable characteristic that the circuit loss is similar to that of series resonant type energy recovery circuit which is very effective method.

• Transactions on Electrical and Electronic Materials
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• v.7 no.2
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• pp.87-89
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• 2006

We investigated the current limiting characteristics of flux-lock type superconducting fault current limiter(SFCL) according to inductance variation of coil 2. The flux-lock type SFCL consists of two coils. The primary coil is wound in parallel to the secondary coil through an iron core, and the secondary coil is connected to the superconducting element in series. The operation of the flux-lock type SFCL can be divided into the subtractive and the additive polarity winding operations according to the winding directions between the coil 1 and coil 2. The current limiting characteristics in two winding directions were dependent of on the ratio of the number of turns of coil I and coil 2. The fault current increased when the number of turns of coil 2 increased in the subtractive polarity winding. On the contrary, the fault current decreased under the same conditions in case of the additive polarity winding.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.46-50
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• 1996

Die sinking Electrical Discharge Machining(EDM) of TiC/Al$_2$O$_3$Ceramic Matrix Composite(CMC) was conducted for positive and negative polarity according to the change of current and Duty Factor(DF). Also FEM analysis about temperature distribution of workpiece by one spark was executed. Maximum surface roughness( R$_{max}$ ) and SEM photographs of the EDMed surface for different conditions were evaluated. Higher Material Removal Rate(MRR) was obtained for negative polarity than positive one. Better surface morphology was found as the current is decreased, but the MRR was also decreased. From the SEM photographs, the size of melt cavity due to one spark is about 100 to 150${\mu}{\textrm}{m}$ in diameterer

• Korean Journal of Materials Research
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• v.24 no.3
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• pp.135-139
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• 2014

To obtain the transistor with ambipolar transfer characteristics, IGZO/SiOC thin film transistor was prepared on SiOC with various polarities as a gate insulator. The interface between a channel and insulator showed the Ohmic and Schottky contacts in the bias field of -5V ~ +5V. These contact characteristics depended on the polarities of SiOC gate insulators. The transfer characteristics of TFTs were observed the Ohmic contact on SiOC with polarity, but Schottky contact on SiOC with low polarity. The IGZO/SiOC thin film transistor with a Schottky contact in a short range bias electric field exhibited ambipolar transfer characteristics, but that with Ohmic contact in a short range electric field showed unipolar characteristics by the trapping phenomenon due to the trapped ionized defect formation.

• Journal of Microbiology
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• v.44 no.3
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• pp.311-319
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• 2006

Bud6p is a component of a polarisome that controls cell polarity in Saccharomyces cerevisiae. In this study, we investigated the role of the Candide albicans Bud6 protein (CaBud6p) in cell polarity and hyphal development. CaBud6p, which consists of 703 amino acids, had 37% amino-acid sequence identity with the Bud6 protein of S. cerevisiae. The homozygous knock-out of CaBUD6 resulted in several abnormal phenotypes, such as a round and enlarged cells, widened bud necks, and a random budding pattern. In hypha-inducing media, the mutant cells had markedly swollen tips and a reduced ability to switch from yeast to hypha. In addition, a yeast two-Hybrid analysis showed a physical interaction between CaBud6p and CaAct1p, which suggests that CaBud6p may be involved in actin cable organization, like Bud6p in S. cerevisiae. Taken together, these results indicate that CaBud6 plays an important role in the polarized growth of C. albicans.