• Journal of The Korean Astronomical Society
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• v.28 no.2
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• pp.119-137
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• 1995

The $UBVI_{KC}$ CCD photometry was performed in the central region(${\sim}20'{\times}20'$) of the extremely young open cluster IC1805. Member stars were selected in the (B-V)-(U-B) and (V-I)-(B-V) color-color planes. Applying recent stellar evolutionary models, we derived the age, age-spread, and initial mass function(IMF) of the cluster. IC1805 was found to be an extremely young($t_{age}{\sim}1.5Myr$) and has a flat IMF with the slope of ${\Gamma}=-1.0{\pm}0.2$.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.41.2-41.2
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• 2015

We have performed deep wide-field CCD photometry of the young open cluster IC 1805 in the famous star forming region W4, and obtained photometric data for more than 91,000 stars in the field of IC 1805 based on observations with the 3.6m CFHT and the AZT-22 1.5m telescope at Maidanak Astronomical Observatory in Uzbekistan. The photometric data cover an area $43^{\prime}{\times}45^{\prime}$ which is far larger and far deeper than any other optical observations made for the cluster. In order to select the young stellar objects with mid-IR excess emission, we have performed mid-IR photometry of the cluster using the archival images obtained with the Spitzer Space Telescope IRAC and MIPS instruments. From a preliminary analysis of the data, we determined the reddening law ($R_V=3.02{\pm}0.05$), distance modulus ($V_0-M_V=11.9{\pm}0.2$), and the spatial distribution of members.

• The Bulletin of The Korean Astronomical Society
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• v.7
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• pp.8.2-8.2
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• 1982

• The Bulletin of The Korean Astronomical Society
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• v.19
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• pp.22.1-22.1
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• 1994

• Bulletin of the Korean Chemical Society
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• v.24 no.12
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• pp.1805-1808
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• 2003

The simultaneous determination of As(III), As(V), and DMA has been performed by ion chromatography (IC) coupled with inductively coupled plasma-mass spectrometry (ICP-MS). The separation of the three arsenic species was achieved by an anionic separator column (AS 7) with an isocratic elution system. The separated species were directly detected by ICP-MS as an element-selective detection method. The IC-ICP-MS technique was applied for the determination of arsenic species in a NIST SRM 1643d water sample. An As(III) only was detected in the sample. The detection limits of As(III), As(V) and DMA were 0.31, 0.45, and 2.09 ng/mL, respectively. It was also applied for the determination of arsenic species in a human urine obtained by a volunteer, and three arsenic species were identified. The determination of total As in human urines that were obtained from 25 volunteers at the different age was also carried out by ICP-MS.

• The Bulletin of The Korean Astronomical Society
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• v.28 no.1
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• pp.67-67
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• 2003

• Journal of The Korean Astronomical Society
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• v.16 no.1
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• pp.7-17
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• 1983

During the period between January and November in 1982, UBV photoelectric observations were made for 48 stars in NGC 2264, 66 stars in IC 1805 and 22 stars in IC 348. From these observations, various physical parameters such as distance, mean color excess, total-to-selective extinction ratio and mean age of the clusters were determined. Making use of these parameters, the star formation rates were examined for IC 348 and NGC 2264. The overall formation rate is found to be increase rapidly during the period of the active star formation. The age spread (ranging from $5\times10^6$ yrs to $10^7$ yrs) of stars in a given cluster appears to be real which occurs in the extremely young open clusters.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.72.3-72.3
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• 2019

OB associations are young stellar systems on a few tens to a hundred parsec scale, and many of them are composed of multiple substructures. It is suggested that some hints about their formation process are probably imprinted on structural features and internal kinematics. In this context, we study the massive star forming region W4 in the Cassiopeia OB6 association using the Gaia proper motion data and high-resolution optical spectra taken from Hectochelle on MMT. We probe the structure and internal kinematics of W4 to trance its formation process. Several nonmembers with different kinematic properties are excluded in our sample. Some of them may be young stellar population spread over a large area of the Perseus spiral arm given their wide spatial distribution over 50 parsecs. W4 is composed of an central open cluster (IC 1805) and an extended stellar component. Their global expansion patterns are detected in stellar proper motion. In this presentation, we will further discuss the formation process of W4, based on the velocity dispersions of stars comprising these substructure.