• Elastomers and Composites
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• v.49 no.2
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• pp.155-159
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• 2014

High resolution ultrasonic spectroscopy was used to observe the oxidation of [$C_{70}$]fullerene with 3-chloroperoxy benzoic acid in 1,2-dichlorobenzene. UV-vis spectroscopy and X-ray diffraction confirmed the resulting roducts of [$C_{70}$]fullerene oxidation.

• Proceedings of the Optical Society of Korea Conference
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• 1990.02a
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• pp.211-214
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• 1990

Investigation of GaAs/AlGaAs QW carried out by using PL and Absorption spectroscopy. In order to get high resolution (0.76meV) and low noise, proper experimental system was set-up. From measurements, we have deduced the properties of GaAs/AlGaAs QW, such as the residual impurity, well thickness, crystal quality, interface abruptness and well thickness uniformity. Also we can obtain other properties such as sub-band absorption by using Absorption Spectroscopy.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2345-2350
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• 2011

Variable temperature high-resolution $^{19}F$ magic angle spinning (MAS) solid-state NMR spectroscopy was used to characterize fluorocarbon (FKM) rubbers. The high-resolution spectra of copolymers made from two monomers, vinylidene fluoride and hexafluoropropene, and terpolymers composed of vinylidene fluoride, hexafluoropropene, and tetrafluoroethylene, were obtained using MAS speeds of up to 18 kHz combined with high temperatures of up to 200 $^{\circ}C$ at a magnetic field strength of 9.4 Tesla. From these high resolution solid-state NMR spectra, we were able to assign the spectral peaks and differentiate the copolymer FKM from the terpolymer FKM. We also determined quantitatively the monomer compositions of each FKM rubber.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.87.2-87.2
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• 2016

As an era of nano science approaches, the understanding on the shape and optical properties of various materials in a nanoscale range is getting important more seriously than ever. Accordingly the development of high spatial-temporal-spectral resolution measurement tools for characterization of nanomaterials/structures is highly required. Generally, the various properties of sample can be measured independently, e.g. to observe the structural property of sample, we use the scanning electron microscopy or atomic force microscopy, and to observe optical property, we have to use another independent measurement tool such as photoluminescence spectroscopy or Raman spectroscopy. In the case of nano-materials, however, it is very difficult to find out the same position of sample at every different measurement processes, and the condition of sample can be changed by the influence of first measurement. The tip enhanced Raman scattering(TERS), which can simultaneously measure the two or more information of sample with nanoscale spatial resolution, is one of solutions of this problem. In this talk, I will present our recent nano Raman scattering data of graphene that measured by TERS and optimized tip fabrication method for efficient experiment.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.77.4-78
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• 2017

The presence of double red clump (RC; metal-rich counterpart of horizontal-branch) in high latitude field of the Milky Way (MW) bulge is widely interpreted as evidence for an X-shaped structure originated from the bar instability. However, Lee et al. (2015) recently suggested an alternative model, according to which the double RC is metal-rich manifestation of multiple stellar population phenomenon observed in globular clusters (GCs). Here we show that stars in bright RC are enhanced in CN compared to those in faint RC from our low-resolution spectroscopy. CN traces N, and N-rich stars are also enhanced in Na and He in GCs. Since GCs are the only environment that produce second generation stars with enhanced N, Na, & He, this is a direct evidence that stars in the classical bulge component of the MW were mostly provided by proto-GCs.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.302-305
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• 2007

During the CareBeijing campaign in September 2006, Imaging Differential Optical Absorption Spectroscopy (IDOAS) measurements were made over the city of Beijing, China using a spatial resolution of 146 pixels horizontally and 61 pixels vertically, each with a field of view of $0.133^{\circ}$ and $0.072^{\circ}$ in the horizontal and vertical directions, respectively. Using Fraunhofer reference spectra (FRS) for the evaluation of data for two consecutive days, the diurnal variation of $NO_2$ distributions was determined from data measured every single hour from 08:00 until 16:00 on September 9 and 10. Both days presented a fairly clear sky with high visibility. The setup allowed detailed images of the low surface $NO_2$ distribution over Beijing. Images with less than a 30-min temporal resolution showed variation of plume dispersal in both horizontal and vertical directions. An in-situ measurement was also conducted. Results from both instruments are interpreted by considering local emission sources and wind conditions.

• KSBB Journal
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• v.27 no.4
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• pp.199-206
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• 2012

Chiral crown ethers are synthetic macrocyclic polyethers that bind protonated chiral primary amines with high selectivity and affinity. They have been widely used to separate or distinguish the enantiomers of chiral compounds containing a primary amino moiety by high-performance liquid chromatography, capillary electrophoresis, and NMR spectroscopy. In this paper, two important chiral crown ethers including chiral binaphthyl unit and (18-crown-6)-2,3,11,12-tetracarboxylic acid as chiral selectors are focused. And several chiral resolution techniques and their applications in chirotechnology using these chiral crown ethers with related chiral recognition mechanism studies are reviewed. Especially, it was shown that the commercially available HPLC columns based on (18-crown-6)-2,3,11,12-tetracarboxylic acid have been developed and successfully applied for the resolution of various primary amino compounds including amino acids.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.42.3-42.3
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• 2019

The high-resolution near-infrared (NIR) spectroscopy can reveal the evidence of the accretion burst (e.g., the broadened absorption features produced by the Keplerian disk motion) although the moment of the outburst was not caught. The embedded protostar IRAS 16316-1540 observed with the Immersion Grating Infrared Spectrograph (IGRINS, $R={\Delta}{\lambda}/{\lambda}{\sim}45000$) shows the broad absorption features in atomic and CO transitions, as seen in FU Orionis objects (FUors), indicative of an outburst event. We examine whether the spectra of IRAS 16316-1540 arise from the rotating inner hot gaseous disk. Using the IGRINS spectral library, we show that the line profiles of IRAS 16316-1540 are more consistent with an M1.5 V template spectrum convolved with a disk rotation profile than the protostellar photosphere absorption features with a high stellar rotation velocity. We also note that the absorption features deviated from the expected line profile of the accretion disk model can be explained by a turbulence motion generated in the disk atmosphere. From previous observations that show the complex environment and the misaligned outflow axes in IRAS 16316-1540, we suggest that an impact of infalling clumpy envelope material against the disk induces the disk precession, causing the accretion burst from the inner disk to the protostar.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1334-1336
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• 2001

In this study, laser ablation atomic fluorescence (LAAF) spectroscopy has been applied for a nanometer-scale surface analysis of Na-doped polymethyl methacrylate (PMMA). LAAF spectroscopy is a new sensitive element detection technique which involves atomizing of a sample by the laser ablation and detection of ablated plume by laser-induced fluorescence (LIF) spectroscopy. Using this technique in the detection of Na atoms with Na-doped PMMA, a detection limit is obtained as 36 fg for single laser shot. Further, the depth distribution in the sample is measured with a very high spatial resolution using a two-layer PMMA sample by observing the shot-by-shot LIF intensity from the Na atoms.

• Journal of The Korean Astronomical Society
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• v.40 no.4
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• pp.183-186
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• 2007

The spectroscopic properties of bright extragalactic planetary nebulae are reviewed, considering primarily their chemical abundances and their internal kinematics. Low-resolution spectroscopy is used to investigate how the precursor stars of bright planetary nebulae modify their original composition through nucleosynthesis and dredge up. At present, the evidence indicates that oxygen and neon abundances usually remain unchanged, helium abundances are typically enhanced by less than 50%, while nitrogen enhancements span a very wide range. Interpreting these changes in terms of the masses of their progenitor stars implies that the progenitor stars typically have masses or order $1.5M_{\bigodot}$ or less, though no models satisfactorily explain the nitrogen enrichment. High-resolution spectroscopy is used to study the internal kinematics of bright planetary nebulae in Local Group galaxies. At first sight, the expansion velocities are remarkably uniform, with a typical expansion velocity of 18 km/s and a range of 8-28 km/s, independent of the progenitor stellar population. Upon closer examination, bright planetary nebulae in the bulge of M31 expand slightly faster than their counterparts in M31's disk, a result that may extend generally to the planetary nebulae arising from old and young stellar populations. There are no very strong correlations between expansion velocity and global nebular properties, except that there are no large expansion velocities at the highest $H{\beta}$ luminosities (i.e., the youngest objects never expand rapidly). These results independently suggest that bright planetary nebulae arise from a similar mass range in all galaxies. Nonetheless, there are good reasons to believe that bright planetary nebulae do not arise from identical progenitor stars in all galaxies.