• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.173-174
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• 2005

On behalf of the IRSF/SIRIUS group, I introduce some recent results from our deep near-infrared surveys (J, Hand Ks bands, limiting magnitude of Ks=17) toward star forming regions in the Milky Way Galaxy (MWG) and Large Magellanic Cloud (LMC) with the near-infrared camera SIRIUS. We discovered a rich population of low-mass young stellar objects associated with the W3 and NGC 7538 regions in the MWG based on the near-infrared colors arid magnitudes. The high sensitivity of our survey enables us to detect intermediate-mass pre-main sequence stars, i.e. HAEBE stars, even in the LMC. We detected many HAEBE candidate stars in the N159/N160 complex star forming region in the LMC with the IRSF 1.4-m telescope. Spatial distributions of the young stellar objects indicate the sequential cluster formation in each star forming region in the complex and large scale (a few ${\times}$ 100 pc) sequential cluster formation over the entire complex.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.54.1-54.1
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• 2016

Stellar wind and radiation pressure from massive stars can trigger the formation of new generation of stars. The sequential age distribution of stars, the morphology of cometary globules, and bright-rimmed clouds have been accepted as evidence of triggered star formation. However, these characteristics do not necessarily suggest that new generation of stars are formed by the feedback of massive stars. In order to search for any physical connection between star forming events, we have initiated a study of gas and stellar kinematics in NGC 1893, where two prominent cometary nebulae are facing toward O-type stars. The spectra of gas and stars in optical and near-infrared (NIR) wavelength are obtained with Hectochelle on the 6.5m MMT and Immersion GRating INfrared Spectrograph on the 2.7m Harlan J. Smith Telescope at McDonald observatory. In this study, the radial velocity field of gas across the cluster is investigated using $H{\alpha}$ and [N II] ${\lambda}$ 6584 emission lines, and that of the cometary nebula Sim 130 is also probed using 1-0 S(1) transition line of $H_2$. We report a distinctive velocity field of the cometary nebulae and many ro-vibrational transitions of $H_2$ even at high energy levels in the NIR spectra. These properties indicate the interaction between the cometary nebulae and O-type stars, and this fact can be a clue to triggered star formation in NGC 1893.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.325-327
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• 2003

망 자원의 효율적인 사용, 관리 및 기존의 망을 흡수 통합하기 위해서 차세대통합네트워크(NGcN), ALL­IP 망으로 망 진화가 이루어지고 있으며, 이에 따라 동기식 CDMA2000 과 비동기식 WCDMA의 이동 통신망도 통합 및 연동에 대한 연구가 진행되고 있다. 그리고, 망 개방화에 대한 분위기도 고조되는 상황에서 CDMA2000, WCDMA등과 같은 서로 다른 무선 액세스 망에서 동일한 게이트웨이를 통하여 무선인터넷 서비스를 제공하려는 움직임도 있다. 본 논문에서는 망 진화에 따른 망통합 및 연동과 망 개방에 따른 COMA200 과 WCDMA 의 서로 다른 무선인터넷 액세스를 동시에 지원하기 위한 시스템인 A­MiDAS(Advanced Mobile internet Data Access System)에 대해서 소개하고, A­MiDAS 내의 CDMA2000 과 WCDMA 를 수용하기 위해서 설계 및 개발된 MNAB(Mobile Network Access Board)에 대해서 기술한다.

• Journal of Astronomy and Space Sciences
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• v.11 no.2
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• pp.208-231
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• 1994

We have undertaken CCD observations of fie이 standard stars with H$\beta$ photometric system to investigate the reliability of H$\beta$ CCD photometry. Flat fielding with dome flat and sky flat for H$\beta$w and H$\beta$n filter was compared with that of B filter in UBV system and, from these, we have not found any difference. It was confirmed that there is a good linear relationship between our H$\beta$ values observed with 2.3m reflector and standard values. However, H$\beta$ values observed with 60cm reflector at Sobaeksan Astronomy Observatory showed very poor relationship. To investigate the accuracy of H$\beta$ CCD photometry for fainter objects, open cluster NGC2437 was observed and reduced with DoPHOT, and the results were compared with those for photoelectric photometry of Stetson(1981).

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.29.5-30
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• 2016

(1) The correlation between the mass of supermassive black holes (SMBHs) and the properties of their host galaxies suggests that SMBHs and host galaxies are closely linked in their formation and evolution. While the exact origin of their relationship is still under debate, theoretical models often invoke feedback from active galactic nuclei as a crucial mechanism for establishing the BH-host correlation. In the first part of my talk, I will present our efforts to find observational sign of the AGN feedback in young luminous AGNs. (2) While intermediate-mass black hole (IMBH) is thought be cosmologically important class to understand the link between stellar mass black holes and SMBHs, it is extremely rare in the present-day Universe. In the second part of this talk, I will report a Gemini/GMOS-N IFU study of an ultraluminous X-ray source in NGC 5252, which is a possible candidate of an off-nuclear non-stellar black hole.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.27.4-27.4
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• 2017

(1) The correlation between the mass of supermassive black holes (SMBHs) and the properties of their host galaxies suggests that SMBHs and host galaxies are closely linked in their formation and evolution. While the exact origin of their relationship is still under debate, theoretical models often invoke feedback from active galactic nuclei as a crucial mechanism for establishing the BH-host correlation. In the first part of my talk, I will present possible observational biases in the BH-host relation, and methods to overcome these biases. I will also report our efforts to find observational sign of the AGN feedback in high-z young luminous AGNs. (2) While intermediate-mass black hole (IMBH) is thought be cosmologically important class to understand the link between stellar mass black holes and SMBHs, it is extremely rare in the present-day Universe. In the second part of this talk, I will report a Gemini/GMOS-N IFU study of an ultraluminous X-ray source in NGC 5252, which is a possible candidate of an off-nuclear non-stellar black hole.

• Proceedings of the Korea Society for Simulation Conference
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• 2005.05a
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• pp.1-4
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• 2005

Information communication environment integrates communication, broadcasting and internet, and Digital Convergence service emerges in result. Thus, the effective routers are needed so that they can transmit a huge number of data to core internet through appropriate base center. Therefore, the network guaranteeing QoS in transport layer supports interoperability with different wireless networks. So as to users receive necessary information anywhere seamlessly, the network architecture focuses on packet transmission and it is efficient for the control layer switches and controls packets between different networks. Since individual users take advantage of different services and data, the effective router architecture must be designed. Hence in this paper we design monitoring technique to solve security problem and to support premium service to ultimate users. Thereafter, we run opnet simulation and show the improvement of proposed router architecture.

• Journal of Astronomy and Space Sciences
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• v.3 no.2
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• pp.103-116
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• 1986

The mass distribution and other related quantities were calculated by fitting the observed rotation curve(Davoust and de Vaucouleur 1980) to Brandt and Belton's mass distribution model. One of n values for mass model is determined as 1.5(Vm=95 $kms^{-1}$) and two pairs of them are determined as 0.8(Vm = 95$kms^{-1}$) and 2.0 and 0.8 (Vm = 55$kms^{-1}$) and 2.0 because of the hump in observed rotation curve. Total masses and integrated mass to luminosity ration are $1.8\times10^{10}M_\odot,\;1.5\times10^{10}M_\odot,\;1.4\times10^{10}M_\odot$, and 6.57, 5.33, 5.26 for three cases according to n values. Integrated mass to luminosity ratio in Holmberg radius is 3.44, 3.26, 3.00 in god agreement with the typical value of Sd type suggested by Faber and Gallagher(1979). Presented halo masses which are fifty percent of total masses and halo mass to luminosity ratios given as 75.83, 53.50, 58.75 are values less than Turner's(1976).

• Publications of The Korean Astronomical Society
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• v.9 no.1
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• pp.101-110
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• 1994

We have investigated intensively an optical telescope with 76cm diameter and CCD camera system in astronomical observatory of Kyung Hee university, in order to maximize instrumental functions of our observational equipments and to construct a more reliable photometric system. And computer softwares AUTO DOME, KH CCD and KH PHO for astronomical image observations and their automatic photometries with high accuracy have been made for observers w use our observational system conveniently and efficiently. Throughout careful examinations of these programs, it has been proved that the observing time by our program is shorter than that by manual operations, so that, fast and accurate observations can be executed with ease. For open cluster NGC 7063 observed with S/N value of 350 or more by KH PHO, we have found the magnitude measurements of 11 object stars would show 0.007 magnitude difference, comparing with magnitude data from IRAF/APPHOT. From automatic photometry of eclipsing binary, AB And observed by our software, total 220 data points with good quality have been acquired during 8 hours and so we could make a better light curve than that obtained from any observational results by domestic photoelectric photometry system.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.46.2-46.2
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• 2012

The black hole mass-stellar velocity dispersion ($M_{BH}-{\sigma}_*$) relation observed in the present-day universe has motivated numerous studies on the black hole-galaxy co-evolution. It is crucial to define the$M_{BH}-{\sigma}_*$ local active galaxies since cosmic evolution of the correlations is calibrated based on the local relation. However, stellar velocity dispersion is difficult to measure in active galaxies due to much higher AGN continuum than stellar pseudo-continuum, resulting in a small sample with reliable velocity dispersion measurements for studying the AGN $M_{BH}-{\sigma}_*$ relation. To increase the sample size and improve the measurements, we obtained high S/N near-IR spectra for 3 local AGNs, i.e., NGC 3227, Akn 120, 3C 390.3, for which reverberation black hole masses are measured, using the TripleSpec at the Palomar 5-m Telescope. By investigating aperture effect and correcting for rotation component, we determine the luminosity-weighted ${\sigma}_*$, based on the spatially resolved kinematics and compare them with optical measurements from literature. Combining our new measurements with literature data, we present an improved $M_{BH}-{\sigma}_*$ relation for the enlarged sample of reverberation-mapped AGNs.