• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.101.1-101.1
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• 2014

The fluctuation of VLBI visibility phase can be occurred, predominantly caused by the irregular distribution and motion of water vapor in the atmosphere at high frequencies (>1GHz). This radio-seeing effect shows up on filled-aperture telescopes as an anomalous refraction (AR). This can be shown as if the antenna pointing-offset increases, in other words the apparent displacement of radio sources from its nominal position happens. We carried out the single-dish observations on KVN sites in order to check the effect of AR from 2010 to 2014. Orion KL, U Her, and R Leo were observed with 1second sampling time at 22.235GHz and 43.122GHz simultaneously. Each source was observed with the tracking mode for 30 minutes per a source. We analyzed the structure function, power spectrum and Allan variance of the data according to a day and a night, a season and observatories. Finally, we can infer that the AR effect depends on the atmospheric environment, especially tropospheric turbulence.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.321-322
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• 1996

Using the data on the occurrences of the Ho: and soft X-ray flares for the time interval of January 1, 1986-May :31, 1994, we have studied the middle term(30-300days) pericities of the solar flare production during the activity cycle 22. Power analysis of the time seies of daily H$\alpha$ flare index in the northern hemisphere shows prominent periodicities at 220, 120, 109, and 92 days(see Figures l(a) and l(b)), while in the southern hemisphere, those at 267, 213, 183, 167, and 107 days are apparent, though their peaks are not so distint as those in the northern hemisphere. Periodogram of daily soft X-ray flare index also reveal the periodicities at 279, 205, 164, 117, and 91 days in the northern hemisphere, and at 266, 220, 199, 162, 120, and 100 days in the southern hemisphere. Howeer, the 155-day periodicity reported for the earlier cycles, 19, 20, and 21, could not be confirmed in our analysis. to be submitted to Solar Physics; an extended abstract.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.51.1-51.1
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• 2012

We observed low-z quasar PG1426+015 (z=0.086), using the near-IR high resolution echelle spectrometer, IRCS, at the SUBARU 8.2 m telescope. Using an Adoptive Optics system, the full width at half maximum of the point spread function was about 0.3 arcsec, which can effectively separate the quasar spectra from the host galaxy spectra. We also maximize the total exposure time up to several hours per target, and develop data reduction methods to increase the signal-to-noise ratios. This poster presents the data reduction processes and sample spectra from the quasar and its host galaxy. These spectral lines will be used to study the physical mechanism of quasars, and the velocity dispersions of the stars in the bugle of the host galaxy.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.61.2-61.2
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• 2012

We observed selected super cluster regions in M82 with 5'5 arcsec field-of-view using near-IR high resolution echelle spectrometer, IRCS, at the SUBARU 8.2 m telescope. The slit width of 0.15 arcsec makes the high resolution (R ${\approx}$ 20,000) spectra in the H and K bands. In this poster, we present sample spectra of [FeII] lines and ro-vibration lines of $H_2$ which trace ionic shocks in the intercloud regions and molecular shocks. The line widths of $Br{\gamma}$ line are also measured to derive the velocity dispersion within the super star clusters.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.58.2-58.2
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• 2017

The special session of the East Asian Observatory was prepared to let the Korean Astronomical Community know the current status and future prospect of the EAO, and to hear the opinion from the community. The East Asian Observatory (EAO) was formulated on September 5, 2014 by East Asian Core Observatories Associations (EACOA) as a non-profit company registered in the State of Hawaii. As a first mission of the EAO, it has successfully operated the James Clerk Maxwell Telescope (JCMT) since March 2015. The Submillimeter Array (SMA) has been available to the East Asian astronomers from 2017A season through the EAO, and the Subaru and the East Asian VLBI Network (EAVN) are the possible facilities to be available in near future.

• Journal of Industrial Technology
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• v.30 no.B
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• pp.91-98
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• 2010

Recently, there has been enormous damage due to river floodings caused by localized heavy rains. The direct discharge triggered by those torrential rains inflicts severe property damage on the residents of nearby areas. To minimize the possibility of river floodings in case of heavy rains and to predict the possible damage, the management of existing rainfall and water level observatories should be checked and prediction methods based on the characteristics of water usage and floodgate of nearby rivers must be further analyzed. Therefore, this research analyzed the water level change predictions on different spots with a regression equation of rainfall and water levels, using the observation data of the water level observatory in Jeongseon-gun, Gangwon Province and the rainfall observatory which are located on the upper region of the Han river.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.83.1-83.1
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• 2010

In the last meeting of KAS, we reported the first statistical study of Faraday rotation measure (RM) in the large-scale structure of the universe using the data of cosmological structure formation simulations. With a turbulence dynamo model for the intergalactic magnetic field (IGMF), we predicted that the root mean square of RM through filaments is \sim 1 rad/m^2. Future radio observatories such as the Square Kilometer Array (SKA) could detect this signal level. However, it is known that the typical foreground galactic RM is a few tens and less than ten rad/m^2 in the low and high galactic latitudes, respectively. So the RM in the large-scale structure could be detected only after the foreground galactic RM is removed. In this talk, we show how we remove the foreground galactic RM and what we obtain from the masked data, by using some noise models and masking techniques. Our results can be used to simulate future RM observations by SKA, and eventually to constrain the origin and evolution of the IGMF in the large-scale structure.

• Water Engineering Research
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• v.4 no.4
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• pp.187-192
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• 2003

The rainfall observation systems have largely been improved in Japan. The Japan Meteorological Agency, prefecture governments, and other administrative bodies have also increased the number of rain gauges thru out the country. The density of observatories is now one per several $\km^2$. Heavy rainfall information systems have been improved. Besides it, the Internet was popularized in the late 1990s, and has been used to transmit data of heavy rainfall. Internet accessible cellular phones have been popular in Japan since 1999. Such phones are expected to be useful in the field of disaster warning announcements, because they can automatically notify users bye-mail of pending disasters. The use of the Internet during natural disasters is groundbreaking in Japan today. However, in order to use disaster information effectively on Internet it is necessary to investigate how to use the information during the rainfall disaster. Therefore in our study we suggest methods on the effective construction and their use of information technology on Internet.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.68.2-68.2
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• 2011

We present the detailed image decomposition of Hubble Space Telescope archival images for 235 nearby (z < 0.35) unobscured type 1 AGNs. It allows us to perform robust measurements of host galaxy properties and AGN luminosity contribution. We examine how the host properties correlate with AGN properties. Broad line type 1 and radio-loud AGNs are hosted preferentially by early type galaxies. Narrow line type 1 AGNs show a low fraction of tidal interaction, that might suggest the secular evolution may play an important role for triggering AGN activity, while the fraction of merging hosts is rather higher in luminous AGNs. We compare the nucleus luminosity and bulge luminosity and find that either our sample might have a smaller zero point in the M(BH)-L(bulge) relation (i.e. less massive black hole at a given bulge luminosity) relation compared to the normal galaxies or Eddington ratio of our sample could be systematically overestimated.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.E2
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• pp.63-73
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• 2003

The atmospheric pollution distribution in the industrial area of Yosu in Korea is calculated using numerical model and the model is validated by comparing the calculations with observed data. The emission of NO$_{x}$ and SO$_{x}$ was estimated for 6 sources, and the emission amount of HC was estimated for 9 anthropogenic sources. The calculated wind speed, wind direction and temperature agreed well with the observed data at two observatories, and the calculated concentration of NO, NO$_2$, $O_3$ and SO$_2$ were also reasonable for 5 monitoring stations. The validity of the model is evaluated using 3 indexes of the EPA, and the model is found to be valid and accurate.ate.