• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1637-1642
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• 2013

We carried out the melt copolymerization reactions of 1,2-bis(diethylamino)tetramethyldisilane with several aryldiols such as, 4,4'-biphenol, 4,4'-isopropylidenediphenol, 9H-fluoren-9,9-dimethanol, and 4,4'-(9-fluorenylidene) bis(2-phenoxyethanol) to afford poly[oxy(arylene)oxy(tetramethyldisilylene)]s containing fluorescent aromatic chromophore groups in the polymer main chain: poly[oxy(4,4'-biphenylene)oxy(tetramethyldisilylene)], poly[oxy{(4,4'-isopropylidene) diphenylene}oxy(tetramethyldisilylene)], poly[oxy(9H-fluorene-9,9-dimethylene) oxy(tetramethyldisilylene)], and poly[oxy{4,4'-(9-fluorenylidene)bis(2-phenoxyethylene)}oxy(tetramethyldisilnylene)]. These prepared materials are soluble in common organic solvents such as $CHCl_3$ and THF. The obtained polymers were characterized by several spectroscopic methods such as $^1H$, $^{13}C$, and $^{29}Si$ NMR. Further, FTIR spectra of all the polymers exhibited characteristic Si-O stretching frequencies at 1014-1087 $cm^{-1}$. These polymeric materials in THF showed strong maximum absorption peaks at 268-281 nm, strong maximum excitation peaks at 263-291 nm, and strong maximum fluorescence emission bands at 314-362 nm due to the presence of tetramethyldisilylene and several arylene chromophores in the polymer main chain. TGA thermograms indicated that most of the polymers were stable up to $200^{\circ}C$ with a weight loss of 3-16% in nitrogen.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.284-289
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• 2003

The narrow band-averaged transmissivity of $CO_2-H_2O$ mixtures is expressed by multiplying the transmissivities of $CO_2$ and $H_2O$. Applying the multiplication property of narrow band transmissivities for gas mixtures of $CO_2-H_2O$, the number of gray gases, required for accurate representation of the absorption characteristics by using the narrow band based WSGGM, is significantly increased. To reduce the computational loads by reducing the number of gray gases, we propose a gray gas regrouping process where the gray gases used for the WSGGM are regrouped into a specified number of groups according to the magnitudes of absorption coefficients. To evaluate the proposed WSGGM for gas mixtures, the radiative transfer problems through three-dimensional gas media are considered. The radiative source terms and the radiative heat fluxes obtained by using the proposed method are fairly well compared to those obtained by using the SNB model. The regrouping technique results in an excellent computational efficiency with minor loss of accuracy.

• Journal of Magnetics
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• v.8 no.4
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• pp.149-152
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• 2003

The electronic structure of Mn12-Ac molecular magnet has been investigated using synchrotron radiation. The valence-band photoemission spectroscopy (PES) measurement reveals that Mn 3d states are located near the top of the valence band. The trend in the measured valence-band PES spectra is found to be consistent with that in the calculated local density of states. The Mn 2p x-ray absorption spectroscopy (XAS) measurement provides evidence for the Mn$^{3+}$-Mn$^{4+}$ mixed-valent states.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.237-239
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• 1994

The $NO_2$ gas-detection characteristics were investigated using the functional organic Langmuir-Blodgett(LB) film of Tetra-3-hexadecyl-sulphamoylcopperphthalocyanine(HDSM-CuPc). A surface pressure of 30mN/m was obtained as a proper one for a film deposition. A deposited film status was confirmed by electrical and optical methods such as UV/visible absorption spectra and current-voltage(I-V) characteristics. The $NO_2$ gas response experiments under 200ppm concentration show that there is not increment of electrical conductivity in room temperature and is identified by UV/visible absorption spectra. But There are some increments of electrical conductivity in $160^{\circ}C$.

• Journal of the Korean Chemical Society
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• v.52 no.2
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• pp.140-147
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• 2008

.A new approach for a cloud point extraction-electrothermal atomic absorption spectrometric method was used for determining bismuth. The aqueous analyte was acidified with sulfuric acid (pH 3.0-3.5). Triton X-114 was added as a surfactant and natriumdiethyldithiocarbaminat (Na-DDTC) was used as a complexing agent. After phase separation at 50oC based on the cloud point separation of the mixture, the surfactant-rich phasen was diluted using tetrahydrofuran (THF). Twenty microliters (20 L) of the enriched solution and 10 l of 0.1% (w/v) Pd(NO3)2 as chemical modifier were dispersed into the graphite tube and the analyte determined by electrothermal atomic absorption spectrometry. After optimizing extraction conditions and instrumental parameters, a preconcentration factor of 195 was obtained for a sample of only 10 mL. The detection limit was 0.04 ng ml-1 and the analytical curve was linear for the concentration range of 0.04-0.70 ng mL-1. Relative standard deviations were <5%. The method was successfully applied for the extraction and determination of bismuth in water samples.

• Journal of the Korean Chemical Society
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• v.43 no.4
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• pp.418-422
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• 1999

A method is described for the selective determination of Cr(III) and Cr(VI) in aqueous solutios by flame atomic absorption spectrometry. Selective extraction of $Cr_2O_7^{2-}$ was performed by Aliquat 336/NIBK from the mixtures of $Cr^{3+}$ and $Cr_2O_7^{2-}$, and the extraction of $Cr^{3+}$ was followed after complex formation with citrate by using the same extractant. The concentraction of each analyte in the extract was determined by $N_2O-C_2H_2$ flame atomic absorption spectrometry. The recoveries of $Cr^{3+}$ and $Cr_2O_7^{2-}$ from 50mL of aqueous solution ranging 0.1~1.0 ${\mu}g/mL$ as Cr respectively by single extractions with 5 mL of 1%(V/V) Aliquat 336/MIBK were resulted as 98.8∼101.7%.

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.65.3-65.3
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• 2008

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.49.2-49.2
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• 2019

We present results from our long-term observing campaign, using the NASA IRTF at Maunakea, to obtain 2 - 4 ㎛ spectra of 118 red point sources in the line of sight to the Galactic Center (GC). Our sample is largely composed of point sources selected from near- and mid-infrared photometry, but also includes a number of massive young stellar objects. Many of these sources show high foreground extinction as shown by deep 3.4 ㎛ aliphatic hydrocarbon absorption feature, which is a characteristic of the diffuse ISM and comes from the long line of sight through the diffuse medium toward the Central Molecular Zone (CMZ), the central 300 pc region of the GC. The deep 3.1 ㎛ H₂O ice absorption band coming from the local, dense material in the GC CMZ suggests that most sources are likely located in the GC CMZ. A few of these sources show weak CCH₃OH ice absorption at 3.535 ㎛, which can provide a strong constraint on the CCH₃OH ice formation in the unique environment of the CMZ. From the best-fitting models, the optical depths of these features are determined and used to generate a well-rounded view of the ice composition across the GC CMZ and the spectral characteristics of massive YSOs in the GC.

• Journal of the Korean Chemical Society
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• v.33 no.2
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• pp.203-207
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• 1989

The methyl red stock solution was added to sample solution and the absorbance values of this solution were measured at the maximum absorption wavelengths of the acidic form, the basic form, and the isosbestic point of the indicator. From the measurements of absorbance, the pH of this solution was calculated. The range of absorbance at the isosbestic point was maintained within 0.1 ${\sim}$ 0.3. The error of pH measurement was within ${\pm}0.08$ pH unit in the pH range of sample solution of $pK_I{\pm}1$.

• Transactions of the Korean hydrogen and new energy society
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• v.12 no.3
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• pp.201-209
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• 2001

The change of optical transmittance of $PdH_x$ thin film due to hydrogen concentration change was measured at room temperature. Pd film($312{\AA}$ thick) was made by thermal evaporation on glass substrate. Hydrogen absorption and desorption cycling effect on optical transmittance was measured 4 times in the pressure range between 0 and 640 torr. Ratio of optical transmittance to the change of ln pressure(torr) increases with increasing number of hydrogen A-D cyclings in the ${\beta}$ phase.