• The Bulletin of The Korean Astronomical Society
• /
• v.42 no.2
• /
• pp.87.1-87.1
• /
• 2017

We present preliminary results of elemental abundances of six ultra-metal poor (UMP; [Fe/H] < -4.0) stars derived from high-resolution spectra obtained by Gemini/GRACES. The UMP candidates were selected for the high-resolution follow-up from the low-resolution spectra of Sloan Digital Sky Survey (SDSS). We investigate possible progenitors of the UMP objects by comparing the measured abundance patterns with yields that various supernova models predict. Our results can provide stringent constraints on the mass range of the first generation of stars, which are the progenitors of the UMP objects.

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.1
• /
• pp.79.2-79.2
• /
• 2012

This study is aim to understand the distribution and the property of LISM (local interstellar medium) using the high resolution spectra of the 26 early type stars in the five open clusters ( IC 4665, Stephenson 1, Collinder 359, Roslund 5 and Collinder 70). These spectra have been observed by BOES in Bohyunsan observatory from 2009 November to 2011 Feburary, of which resolution is 45,000. We used IRAF for the data reduction (Bias subtraction, Flat-field division, and wavelength calibration) and DECH for the deriving the equivalent widths of 4 interstellar lines - Ca II K (3934${\AA}$), Na I D (5890, 5896${\AA}$) and K I (7698${\AA}$) and the column densities of those elements in LISM toward the clusters. The results of this study provide clues for better understanding of the LISM toward these clusters.

• Journal of The Korean Astronomical Society
• /
• v.29 no.spc1
• /
• pp.187-188
• /
• 1996

We have mapped $1 deg^2$ region toward a high latitude HII region S73 (l, b) = ($37^{\circ}.69$, $44^{\circ}.55$) and associated molecular cloud in $^{12}CO$ J = 1 - 0, and $^{13}CO$ J = 1 - 0, using the 3 mm SIS receiver on the 14 m telescope at Taeduk Radio Astronomy Observatory. A high resolution autocorrelator is used to resolve extremely narrow CO linewidths (FWHP < 1 km/s) of the molecular cloud. Though the linewidths are very narrow, it is found that there is systematic velocity gradient in the molecular gas associated with the H II region. Both of $^{12}CO$ and $^{13}CO$ averaged spectra are non-gaussian, and there are obvious blue wings in the spectra. It is remarkable that the linewidths at the blueshifted region are broader than those of the rest of the cloud. The CO emission does match well with the dust emission.

• The Bulletin of The Korean Astronomical Society
• /
• v.5
• /
• pp.22.2-22.2
• /
• 1980

• Bulletin of the Korean Chemical Society
• /
• v.15 no.8
• /
• pp.605-606
• /
• 1994

• Mass Spectrometry Letters
• /
• v.3 no.2
• /
• pp.29-38
• /
• 2012

A new approach of volatile compounds analysis is proposed using a linear ion trap Orbitrap mass spectrometer coupled with gas chromatography through an atmospheric pressure photoionization interface. In the proposed GC-HRMS/MS approach, direct chemical composition analysis is made for the precursor ions in high resolution MS spectra and the structural identifications were made through the database search of high quality MS/MS spectra. Successful analysis of a complex perfume sample was demonstrated and compared with GC-EI-Q and GC-EI-TOF. The current approach is complementary to conventional GC-EI-MS analysis and can identify low abundance co-eluting compounds. Toluene co-sprayed as a dopant through API probe significantly enhanced ionization of certain compounds and reduced oxidation during the ionization.

• Nuclear Engineering and Technology
• /
• v.56 no.7
• /
• pp.2799-2805
• /
• 2024

Energy-resolved neutron imaging is an effective way to investigate the internal structure and residual stress of materials. Different sample sizes have varying requirements for the detector's imaging field of view (FOV) and spatial resolution. Therefore, a dual-mode energy-resolved neutron imaging detector was developed, which mainly consisted of a neutron scintillator screen, a mirror, imaging lenses, and a time-stamping optical fast camera. This detector could operate in a large FOV mode or a high spatial resolution mode. To evaluate the performance of the detector, the neutron wavelength spectra and the multiple spatial resolution tests were conducted at CSNS. The results demonstrated that the detector accurately measured the neutron wavelength spectra selected by a bandwidth chopper. The best spatial resolution was about 20 ㎛ in high spatial resolution mode after event reconstruction, and a FOV of 45.0 mm × 45.0 mm was obtained in large FOV mode. The feasibility was validated to change the spatial resolution and FOV by replacing the scintillator screen and adjusting the lens magnification.

• Journal of the Korean earth science society
• /
• v.26 no.2
• /
• pp.160-165
• /
• 2005

A series of high resolution spectra of CH Cygni obtained at the Bohyunsan Optical Astronomy Observatory (BOAO) in April 2004 has been analyzed. The emission components of the [O I] 6300 A lines are de-convoluted and fitted with Gaussian functions in order to investigate the characteristics and the structure of CH Cygni system along with the analysis for $H{\alpha}$ and [O III] lines. A present geometrical structure of the components of CH Cygni system is suggested.

• Publications of The Korean Astronomical Society
• /
• v.19 no.1
• /
• pp.21-25
• /
• 2004

We analyzed the high resolution H,6 line spectra of CH Cygni obtained at the Bohyunsan Astronomical Observatory (BOAO) on April 2004. The temporal changes in the $H\beta$ line profiles are reported. We obtained the equivalent widths of the Gaussian components. Using this we estimated the length of the gaseous nebula which emits the $H\beta$ line and the mass loss rate from the star.

• The Bulletin of The Korean Astronomical Society
• /
• v.43 no.1
• /
• pp.58.3-59
• /
• 2018

We present the results of high resolution spectral analysis for Type Ia supernova SN 2014J in M82, which was discovered on 21 January 2014 UT. We performed spectroscopic observations for SN 2014J in its early phase at Bohyunsan Optical Astronomy Observatory with the high resolution echelle spectrograph BOES attached to 1.8-m reflector. Spectra of 26 epochs in 6 nights were obtained from 22 January 2014 to 23 February 2014 UT. Spectral feature variations for several significant lines including Si II and Ca II lines will be shown and discussed.