• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.93-94
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• 1996

The Galaxy and the Large and Small Magellanic Clouds (LMC and SMC respectively) form a triple system of mutually interacting galaxies. We have carried out a set of N-body simulations on the gravitational interaction of the SMC with the Galaxy and the LMC in order to model prominent features such as the Magellanic Stream, the inter-Cloud Bridge, and the large depth of the SMC which are thought to be products of the tidal interactions among the members of this system.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.197-198
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• 1996

We have carried out $^{13}CO$ J = 1 $\to$ 0 line observations with spatial resolution of 2' toward 17 small globules selected from the catalogue of Clemens & Barvainis (1988) with a selection criterion of [b] $\ge$ 15 degrees using the Nagoya 4-m radio telescope. Overall characteristics and physical parameters are presented and discussed by examining the $^{13}CO$ integrated intensity map for each of the globules.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.45-47
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• 2010

Terrestrial Laser Scanner is widely useful in the cultural heritage documentation, acquisition of three-dimensional spatial information in the field of civil engineering and construction, and the safety monitoring for the inaccessible sites such as a few bridges and landslides. This study deals with the investigation of distance measurement and the performances assesment with waveform clouds-based(TLS).

• Journal of The Korean Astronomical Society
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• v.37 no.4
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• pp.265-268
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• 2004

Molecular clouds present many levels of structure, including clumps and cores of varying size and density. We present a brief summary of these cores, describing their observed physical properties and their place in the star formation process. We conclude with some speculation about pre-proto-stellar stages of molecular cores and the observational challenges in their observation.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.58.1-58.1
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• 2014

We model the polarized dust emission from aligned grains by radiative torques in molecular clouds. We consider various models of molecular clouds and calculate the polarization spectrum from aligned grains by both internal and external radiation fields. We show that some polarization spectrum exhibits the bump at wavelengths ${\lambda}$ < $100{\mu}m$, which can be explained due to the polarized emission from a population of small grains aligned by internal radiation fields. Our polarization spectra can explain the anomalous spectra observed by Hildebrand et al, with the rising polarization toward short wavelengths

• Journal of The Korean Astronomical Society
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• v.27 no.1
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• pp.55-60
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• 1994

The 3mm transitions to CO, $^{13}CO,\;CS,\;HCO^+$, and HCN have been observed toward the compact HII regions in W58 using the 14m Daeduk Radio Telescope (DRT). Some of the observed lines show high-velocity wings resulted from outflowing materials of the compact HII regions. We derive the beam averaged column densities of the observed species and compare their relative abundances. The $HCO^+$ abundance appears to be smaller by about an order of magnitude than those of 'typical' quiet molecular clouds. CS may be a good reference molecule in comparing relative abundances in different physical conditions.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.219-220
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• 2012

We present the results of far-infrared spectroscopic observations of the Large Magellanic Cloud (LMC) with FIS-FTS. We covered a large area across the LMC, including 30 Doradus (30 Dor) and N44 star-forming regions, by 191 pointings in total. As a result, we detect the [OIII] and [CII] line emission as well as far-infrared dust continuum emission throughout the LMC. We find that the [OIII] emission is widely distributed around 30 Dor. The observed size of the distribution is too large to be explained by massive stars in 30 Dor, which are assumed to be enshrouded by clouds with the constant gas density estimated from the [OIII] line intensities. Therefore the surrounding structure is likely to be highly clumpy. We also find a global correlation between the [OIII] and the far-infrared continuum emission, suggesting that the gas and dust are well mixed in the highly-ionized region where the dust survives in clumpy dense clouds shielded from energetic photons. Furthermore we find that the ratios of [CII]/CO are as high as 110,000 in 30 Dor, and 45,000 even on average, while they are typically 6,000 for star-forming regions in our Galaxy. The unusually high [CII]/CO is also consistent with the picture of clumpy small dense clouds.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.5
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• pp.392-401
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• 2009

Ice-crystal clouds observation was conducted using a GIST/ADEMRC Multi-wavelength Raman lidar system in order to measure vertical profile and optical depth at Gwangju ($35^{\circ}$10'N, $126^{\circ}$53'E), Korea in December 2002, and March and April 2003. Ice-crystal clouds at high altitude can be distinguished from atmospheric aerosols by high depolarization ratio and high altitude. Ice-crystal clouds were observed at 5~12 km altitudes with a high depolarization ratio from 0.2 to 0.5. Optical depth of ice-crystal clouds had varied from 0.14 to 1.81. The radiative effect of observed ice-crystal cloud on climate system was estimated to be negative net flux in short wavelength (0.25~$4.0{\mu}m$) and positive net flux in short+long wavelength (0.25~$100{\mu}m$) at top of the atmosphere. Net flux by ice-crys tal cloud per unit optical depth was comparable to that of Asian dust.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.38.2-38.2
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• 2016

How dense cores and filaments in molecular clouds form is one of key questions in star formation. To challenge this issue we started to make a systematic mapping survey of nearby molecular clouds in various environments with TRAO 14m telescope equipped with 16 beam array, in high ($N_2H^+$, $HCO^+$ 1-0) and low ($C^{18}O$, $^{13}CO$ 1-0) density tracers (TRAO Multi-beam Legacy Survey of Nearby Filamentary Molecular Clouds, PI: C. W. Lee). We pursue to dynamically and chemically understand how filaments, dense cores, and stars form under different environments. We have performed On-The-Fly (OTF) mapping observations toward L1251, southern part of Perseus molecular cloud, and Serpens main molecular cloud from January to May, 2016. In total, ~3.5 square degree area map of $^{13}CO$ and $C^{18}O$ was simultaneously obtained with S/N of >10 in a velocity resolution of ~0.2 km/s. Dense core regions of ~1.7 square degree area where $C^{18}O$ 1-0 line is strongly detected were also mapped in $N_2H^+$ 1-0 and $HCO^+$ 1-0. The L1251 and Perseus MC are known to be low- to intermediate-mass star-forming clouds, while the Serpens MC is an active low-mass star-forming cloud. The observed molecular filaments will help to understand how the filaments, cores and eventually stars form in a low- and/or intermediate-mass star-forming environment. In this talk, I'll give a brief report on the observation and show preliminary results of Perseus MC.

• Korean Journal of Remote Sensing
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• v.38 no.1
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• pp.103-110
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• 2022

Since satellite images generally include clouds in the atmosphere, it is essential to detect or mask clouds before satellite image processing. Clouds were detected using physical characteristics of clouds in previous research. Cloud detection methods using deep learning techniques such as CNN or the modified U-Net in image segmentation field have been studied recently. Since image segmentation is the process of assigning a label to every pixel in an image, precise pixel-based dataset is required for cloud detection. Obtaining accurate training datasets is more important than a network configuration in image segmentation for cloud detection. Existing deep learning techniques used different training datasets. And test datasets were extracted from intra-dataset which were acquired by same sensor and procedure as training dataset. Different datasets make it difficult to determine which network shows a better overall performance. To verify the effectiveness of the cloud detection network such as Cloud-Net, two types of networks were trained using the cloud dataset from KOMPSAT-3 images provided by the AIHUB site and the L8-Cloud dataset from Landsat8 images which was publicly opened by a Cloud-Net author. Test data from intra-dataset of KOMPSAT-3 cloud dataset were used for validating the network. The simulation results show that the network trained with KOMPSAT-3 cloud dataset shows good performance on the network trained with L8-Cloud dataset. Because Landsat8 and KOMPSAT-3 satellite images have different GSDs, making it difficult to achieve good results from cross-sensor validation. The network could be superior for intra-dataset, but it could be inferior for cross-sensor data. It is necessary to study techniques that show good results in cross-senor validation dataset in the future.