• 천문학논총
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• 제15권spc1호
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• pp.1-13
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• 2000

We review the early historical developement of astronomical spectrographs, properties of emission line spectra of HII regions in spiral galaxies, and absorption line features of galactic globular clusters. Emission line spectra of HII regions within three spiral galaxies NGC 300, NGC 1365, and NGC 7793, which were observed from AAT/IPCS, had been analysed, and we discuss the abundances of elements in HII regions and the radial abundace gradients through the galaxies. The radial UBV color variations of two globular clusters, NGC 1851 and NGC 2808, were examined for correlations with radial variations of several absorption lines in the integrated spectra, which were obtained from SAAO 74 inch telescope and image tube spectrograph. Nine giant star's spectra in NGC 3201 were also obtained and analysed for the radial abundance gradients in the globular cluster. The results show that the presence of a radial color gradient in a globular cluster is correlated with the presence of abundance gradients. Finally, we suggest some scientific programs for the new high dispersion spectrograph, which will be installed to the BOAO 1.8m telescope.

• 천문학회지
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• 제37권4호
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• pp.193-197
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• 2004

Anomalies in the far-infrared [C II] 158 ${\mu}m$ line emission observed in the central one-kiloparsec regions of spiral galaxies are reviewed. Low far-infrared intensity ratios of the [C II] line to the continuum were observed in the center of the Milky Way, because the heating ratio of the gas to the dust is reduced by the soft interstellar radiation field due to late-type stars in the Galactic bulge. In contrast, such low line-to-continuum ratios were not obtained in the center of the nearby spiral M31, in spite of its bright bulge. A comparison with numerical simulations showed that a typical column density of the neutral interstellar medium between illuminating sources at $hv {\~} 1 eV $ is $N_H {\le}10^{21}\;cm^{-2}$ in the region; the medium is translucent for photons sufficiently energetic to heat the grains but not sufficiently energetic to heat the gas. This interpretation is consistent with the combination of the extremely high [C Il]/CO J = 1-0 line intensity ratios and the low recent star-forming activity in the region; the neutral interstellar medium is not sufficiently opaque to protect the species even against the moderately intense incident UV radiation. The above results were unexpected from classical views of the [C II] emission, which was generally considered to trace intense interstellar UV radiation enhanced by active star formation.

• Journal of Astronomy and Space Sciences
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• 제14권1호
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• pp.59-66
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• 1997

V711 Tau의 채층활동을 조사하기 위하여 자외선 영역의 Mg II 방출선의 세기와 광도 변화의 상관 관계를 유추하였다. 첫째, 가시광선 영역의 광도곡선의 형태와 자외선 영역의 광도곡선의 형태를 비교하고, 둘째, IUE 고분산 스펙트럼에서 Mg II 방출선의 세기를 위상별로 측정하고 방출선 부근의 연속선을 이용하여 자외선 광도곡선을 완성하였다. 방출선의 세기와 광도곡선을 비교한 결과 방출선이 강하게 나타나는 위상, $0.^{p}4$에서는 광도가 어둡게 나타나 최소가 되고, 방출선의 세기가 약할 때는 광도가 밝아져서 최대가 되었다. 이는 자기장이 강한 위상에서는 채층활동과 흑점의 크기가 증가하고 반대로 자기장이 약한 위상에서는 채층활동과 흑점의 크기가 작다는 것을 뜻한다. 그러므로 자기장, 채층활동, 별 표면의 흑점과의 상관 관계가 밝혀지고, V711 Tau의 변광은 표면의 채층활동과 흑점에 의한 것이다.

• Journal of Astronomy and Space Sciences
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• 제35권1호
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• pp.7-18
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• 2018

We have investigated the intensities and full width at half maximum (FWHM) of the high dispersion spectroscopic N III emission lines of AG Peg, observed with the Hamilton Echelle Spectrograph (HES) in three different epochs at Mt. Hamilton's Lick Observatory. The earlier theoretical Bowen line study assumed the continuum fluorescence effect, presenting a large discrepancy with the present data. Hence, we analyzed the observed N III lines assuming line fluorescence as the only suitable source: (1) The O III and N III resonance line profiles near ${\lambda}$ 374 were decomposed, using the Gaussian function, and the contributions from various O III line components were determined. (2) Based on the theoretical resonant N III intensities, the expected N III Bowen intensities were obtained to fit the observed values. Our study shows that the incoming line photon number ratio must be considered to balance at each N III Bowen line level in the ultraviolet radiation according to the observed lines in the optical zone. We also found that the average FWHM of the N III Bowen lines was about $5km{\cdot}s^{-1}$ greater than that of the O III Bowen lines, perhaps due to the inherently different kinematic characteristics of their emission zones.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회논문집(II)
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• pp.677-682
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• 1998

Concrete is an inhomogeneous material consisting of larger aggregates and sand embedded in a cement paste matrix. In this study, an acoustic emission technique has been used to clarify the microscope failure mechanisms of concrete under three point bending test. AE source location has also been done to monitor the activities of internal damage and the progress of microscopic failure path during the loading. The relationship between AE characteristic and microscopic and microscopic failure mechanism is discussed.

• 천문학논총
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• 제20권1호
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• pp.43-48
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• 2005

We present a high resolution spectrum of PU Vul observed at Bohyunsan Optical Astronomy Observatory (BOAO) on April 9, 2004. Permitted emission and nebular lines of PU Vul had been significantly changed compared to all spectra observed since its eruption in 1979. Therefore all new lines should be re-identified and were done so. We do-convoluted a $H{\beta}$ line into several emission components with Gaussian functions. Then we carefully discussed the geometrical feature of PU Vul in April 2004.

• Bulletin of the Korean Chemical Society
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• 제19권7호
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• pp.766-770
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• 1998

On-line preconcentration by direct precipitation with hydroxide has been developed and applied for the analysis of Cd in Inductively Coupled Plasma Atomic Emission Spectrometry. Cadmium is continuously precipitated with hydroxide and dissolved by nitric acid in on-line mode. Currently, the enrichment factor is more than 90 times for 20.0 mL of sample and could be further increased very easily. For a large sample throughput, 1.0 mL of sample loop is used and the enrichment factor is 4.5 with the sampling speed of 15/hr. The method has been applied to the analysis of NIST reference sample and has yielded good results with the certified value.

• 천문학회보
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• 제39권2호
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• pp.81.1-81.1
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• 2014

We utilized a 2-D PDR code developed by Lee et al. (2014) to explore the observed OH line fluxes toward embedded protostars. This 2-D PDR code combines self-consistently the FUV radiative transfer, gas-energetics, chemistry, and line radiative transfer. We modeled two sources, GSS30-IRS1 and Elias29, which show conspicuous line emission in the Herschel/PACS wavelength range. The physical and chemical structure for a given embedded source was derived by fitting the PACS CO line fluxes. After exploring various parameter spaces, we conclude that IR-pumping effect either by the central IR source and dust in-situ is insignificant for OH emission, unlike previous studies. We here present a possible solution for the observed OH fluxes, which require a high OH abundance and temperature at the inner-part of the UV heated cavity wall.

• 천문학회보
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• 제38권1호
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• pp.58.1-58.1
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• 2013

We present $10{\mu}m-35{\mu}m$ Spitzer spectra of the interstellar medium in the Central Molecular Zone (CMZ), the central 210 pc ${\times}$ 60 pc of the Galactic center (GC). We present maps of the CMZ in ionic and $H_2$ emission, covering a more extensive area than earlier spectroscopic surveys in this region. The radial velocities and intensities of ionic lines and $H_2$ suggest that most of the $H_2$ 0-0 S(0) emission comes from gas along the line-of-sight, as found by previous work. We compare diagnostic line ratios measured in the Spitzer Infrared Nearby Galaxies Survey (SINGS) to our data. Previous work shows that forbidden line ratios can distinguish star-forming galaxies from LINERs and AGNs. Our GC line ratios agree with star-forming galaxies and not with LINERs or AGNs.

• 천문학회보
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• 제36권1호
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• pp.53.1-53.1
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• 2011

We investigate the radial properties of the narrow-line region (NLR) in two radio-quiet quasars, PG1012+008 and PG1307+085, using the spectra obtained with the FORS1 at the Very Large Telescope. These high quality spectra with seeing < 0.6" enable us to extract seven two-pixel (0.4") spectra as a function of the radial distance from the accretion disk. In contrast to [OIII] narrow-band imaging, which can be contaminated by starbursts, shock-ionized gas, and tidal tails, we use emission-line diagnostic to determine the true size of the AGN-excited NLR. In this poster, we present the results based on the radial variance of $H{\beta}$ to [OIII] ${\lambda}5007$ ratio. For both targets, the [OIII] emission line exhibits a blue wing, suggesting an outflow of gas. In the case of PG1307+085, the blue wing disappears at the distance of 1". We will discuss the properties of the NLR in detail.