• Journal of The Korean Astronomical Society
• /
• v.29 no.1
• /
• pp.75-81
• /
• 1996

We mapped the $^{13}CO$ line in the dark nebula L134 using the 14-m Taeduck radio telescope with a 57 arcsec beam and one beam spacing. The cloud has a spherical shape with an intensity peak ridge extended from the northwest to the southeast directions. The halfwidth and the radial velocity of the lines peak at the region of the cloud center. The radial velocity decreases from the cloud center towards the north and south directions. The integrated line intensity distributions in the space-velocity plane show some structure and a velocity gradient. The $^{13}CO$ and $H_2CO$ clouds and dark clouds are closely related in space in shape, outer boundary, and intensity peak positions. The $^{13}CO$ integrated line intensity is linearly proportional to the visual extinction.

• Journal of The Korean Astronomical Society
• /
• v.29 no.spc1
• /
• pp.95-95
• /
• 1996

We present the recent results of an HI aperture synthesis mosaic of the Large Magellanic Cloud(LMC), made by combining data from 1344 separate pointing centers using the Australia Telescope Compact Array(ATCA). The resolution of the mosaiced images is 1'.0 (15 pc, using a distance to the LMC of 50 kpc). In contrast with its appearance at other wavelengths, the LMC is remarkably symmetric in HI on the largest scales, with the bulk of the HI residing in a disk of diameter 7.3 kpc. Outer spiral structure is clearly seen, though the features appear due to differential rotation, therefore transient in nature. A good correlation is seen between the supershells previously identified in Halpha (e.g. Meaburn 1980) and HI structures.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.964-967
• /
• 2007

Tilting trains are now an established feature of railway operations throughout the world. For intercity traffic, tilt provides operators with increasing speeds, and therefore enhanced competitiveness, on existing routes where insufficient traffic or a lack of funds precludes the construction of a dedicated new high-speed railway. Appling the tilting train, we can expect 30% of speed up on existing lines, but the stability of the electric current would be low because of tilting the train. Also, the spark between the catenary and pantagraph cause environmental problems such as noise, radio wave malfunction. Therefore, the tilting on pantagraph for the power suppling device is very essential for stable electric power supply.

• The Bulletin of The Korean Astronomical Society
• /
• v.35 no.2
• /
• pp.36.1-36.1
• /
• 2010

The Redshift Search Receiver (RSR) is a sensitive, ultra-wideband spectrometer that is being built at the University of Massachusetts as one of the facility instruments for the 50-m Large Millimeter Telescope (LMT). It consists of four receivers each covering the entire 3 mm window from 74 to 111 GHz instantaneously. The primary goal of the receiver is to detect multiple molecular lines in galaxies at any distance and uniquely determine the redshift, in particular dust-obscured star forming systems at high-z which are not easily accessible. I will present some results from commissioning of the RSR on the Five College Radio Astronomy Observatory 14-m telescope, and discuss the future of the receiver.

• The Bulletin of The Korean Astronomical Society
• /
• v.35 no.1
• /
• pp.70.2-70.2
• /
• 2010

We present near- and mid-infrared images of the Crab Nebula, taken with the Infrared Camera (IRC) onboard the AKARI infrared space telescope. These images have a field-of-view of 10'*10' and show the full extent of the nebula at 3, 4, 7, 11, 15, and 24 um. The Crab nebula in near infrared is dominated by synchrotron emission while, in mid infrared, the ionic forbidden lines of Ar, Ne, S, and Fe makes significant contribution. We separate the line emission from synchrotron emission in 3-15 um AKARI bands using the ISOCAM CVF data, and present separate images for the line and synchrotron emissions in each band. We derive the total synchrotron fluxes of the Crab nebula in these bands, which are used to complete the synchrotron spectral energy distribution of the Crab nebula from radio to X-rays. We discuss the spectral variations of the Crab nebula.

• The Bulletin of The Korean Astronomical Society
• /
• v.35 no.1
• /
• pp.60.2-60.2
• /
• 2010

We have studied the abundance ratio of HNC and HCN toward the Red MSX Sources (RMS) using HCN (J=1-0), HNC (J=1-0), $H^{13}CN$ (J=1-0), $HN^{13}C$ (J=1-0),and $N_2H^+$ (J=1-0) lines observed with the Mopra 22 m radio telescope. The RMS are massive young stellar objects identified by the MSX satellite data combined with the 2MASS data. HCN and HNC (a geometrical isomer of HCN) are among the most basic interstellar molecules. According to our analysis, the column density of HCN is found to be correlated with that of HNC. Additionally, the [HNC]/[HCN] abundance ratio is sensitive to the core temperature because HNC is depleted in high temperature regions. This result is consistent with the previous results seen in low mass starless or protostellar cores.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.1
• /
• pp.71-78
• /
• 2008

In this paper, The voltage waveshapes and the lightning parameters such as peak voltage, rise time, decay time and steepness of the front wave were statistically anal zed from the lightning-induced voltages measured on subscriber telecommunication line by lightning. Induced voltage measurement system to measure and collect the lightning-induced voltages in several regions of Korea was developed and installed in several sites. The distributions of lightning-induced voltages for Tears, regions and seasons were analyzed.

• Proceedings of the KIEE Conference
• /
• 2004.04a
• /
• pp.229-231
• /
• 2004

Tilting trains are now an established feature of railway operations throughout the world. For intercity traffic, tilt provides operators with increasing speeds, and therefore enhanced competitiveness, on existing routes where insufficient traffic or a lack of funds precludes the construction of a dedicated new high-speed railway. Appling the tilting train, we can expect 30% of speed up on existing lines, but the stability of the electric current would be low because of tilting the train. Also, the spark between the catenary and pantagraph cause environmental problems such as noise, radio wave malfunction. Therefore, the tilting on pantagraph for the power suppling device is very essential for stable electric power supply.

• Proceedings of the KIEE Conference
• /
• 2002.11c
• /
• pp.418-421
• /
• 2002

The immunity testing in this study was performed to examine the conducted immunity and radiated immunity in medical instrumentation. Experiments were performed to assess the conducted emission and radiated emission of medical instrumentation such as MRI, ultrasound system, and electro surgical unit etc. The emission testing revolves around conducted emissions (high-frequency currents) on power lines and signal cables. Emission testing also looks at the output of energy through the air (called radiated emissions) and analyzes the strength of those radio-frequency signals generated unintentionally by the electrical medical device that is under test. Finally, this study would provide significant data for furture research or electromagnetic interference and compatibility test in medical instrumentation.

• Journal of The Korean Astronomical Society
• /
• v.15 no.1
• /
• pp.9-18
• /
• 1982

To derive the distributions of electron density, temperature and gas-phase metal abundances within the Orion Nebula, we have performed a non-LTE analysis to the radio observations of hydrogen recombination lines and continuum flux over the frequency range from 0.1GHz to 100GHz. We have explicitly included the thermal balance condition in our analysis, hence our derived distributions have their internal consistencies. This enables us to derive the radial distribution of Oxygen and Nitrogen. The gas-phase concentrations of these cooling agents show about the solar values at the very central part of the nebula, then, decrease slowly outward, and finally become about one quarter of the solar values in the outer extended envelope. Such an outward decrease is interpreted as an outward increase of dust concentrations in the Orion.