• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.199-202
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• 2006

One of the major sources of error in precise GPS positioning since the turn-off the Selective Availability(SA) is the ionospheric propagation delay. For the last decades, a lot of the ionospheric researches based on a GPS network have been implemented throughout the world. Especially researches of the ionospheric modeling for Wide Area Argumentation System(WAAS) have been undertaken and published. In mid-latitude regions, typical spatial and temporal variations in ionospheric models delay tend to minimal. The developed ionospheric model calls for a 1.25 degree grid at latitudes and a 2.5 degree grid at longitudes. The precise grid TEC estimated by the inversion technique is also compared with global ionosphere maps(GIMs) which have been provided by several analysis centers(ACs). The results of initial investigations into the suitability of the proposed ionospheric modeling scheme in north-east Asia are presented.

• 천문학논총
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• 제27권4호
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• pp.129-134
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• 2012

The North Ecliptic Pole (NEP) Wide survey covered about 5.4 $deg^2$, a nearly circular area centered on the NEP, using nine passbands of InfraRed Camera (IRC). We present the photometric properties of the data sets, and the nature of the sources detected in this field. The number of detected sources varied according to the filter band: with about 109,000 sources in the NIR, about 20,000 sources in the MIR-S, and about 16,000 sources seen in the MIR-L channel. The $5{\sigma}$ detection limits are about 21 mag in the NIR and 19.5 - 18.5 mag in the MIR bands in terms of the AB magnitude. 50% completeness levels are about 19.8 mag at $3{\mu}m$, 18.6 mag at $9{\mu}m$, and 18 mag at $18{\mu}m$ band (in AB magnitude), respectively. In order to validate the detected sources, all of them are confirmed by matching tests with those in other bands. The 'star-like' sources, defined by the high stellarity and magnitude cut from the optical ancillary data, appear statistically to have a high probability of being stars. The nature of the various types of extragalactic sources in this field are discussed using the color-color diagrams of the NIR and MIR bands with the redshift tracks of galaxies providing useful guidelines.

• Journal of Astronomy and Space Sciences
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• 제22권4호
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• pp.527-536
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• 2005

태양과 달에 의한 섭동력은 정지궤도 위성 궤도 평면의 수직 방향으로 영향을 미쳐 궤도경사각과 승교점 적경을 변화시킨다. 궤도경사각의 변화는 정지궤도 위성의 직하점 위도를 변화시키며 그 크기는 궤도경사각 크기와 같다. 따라서 추력기를 사용하여 위성의 궤도경사각과 승교점 적경을 조정함으로써 직하점 위도를 일정한 범위 내에서 유지시킬 필요가 있으며 이것이 정지궤도 위성의 남북방향 위치유지 (North-South station keeping)이다. 본 연구에서는 Track-Back Chord Target(TBCT), Maximum Compensation Target(MCT), Minimum Fuel Target(MFT) 기법의 비교 분석을 통해 통신해양기상위성 1호에 가장 적합한 남북방향 위치유지 기법을 결정하였다. 비교분석을 위해 세 가지 기법을 이용하여 2008년 12월부터 1년간 남북방향 위치유지 시뮬레이션을 수행하였다. 그 결과 통신해양기상위성 1호의 남북방향 위치유지 기법으로 1년간 필요한 속도증분이 가장 적은 MFT 기법과 위치유지시 궤도경사각 진화 범위가 가장 작은 TBCT 기법이 적합하다고 판단하였다.

• 천문학회보
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• 제45권1호
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• pp.35.3-36
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• 2020

The Time Domain Field is one of the future GTO program fields of JWST(JWST/GTO TDS), surveying about 14' diameter field at the North Eliptical Pole(NEP) with NIRCam/NIRISS. As a part of the multi-wavelength study of the field, we have obtained SCUBA-2 850㎛ mapping which reaches a depth of σrms = 0.9mJy/beam and detect 93 sources at S/N > 3.5 ― which are expected to be highly star-forming (SFR>400M◉/yr) galaxies at z ≳ 1.5-4 and pinpoint the location at <0. " 1 accuracy of 68 sub-mm sources by identifying VLA 3GHz radio counterparts. In this talk, we will introduce the SCUBA-2 JWST/GTO TDS project and the newly discovered sub-mm sources in this field.

• 천문학논총
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• 제30권2호
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• pp.409-411
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• 2015

Galaxy clusters, the largest gravitationally bound systems, are an important subject of study to place constraints on cosmological models. Moreover, they are excellent places to test galaxy evolution models in connection to their environments. To date, massive clusters have been found unexpectedly (Kang & Im 2009; Gonzales et al. 2012) and the evolution of galaxies in clusters is still controversial (Elbaz et al. 2007; Faloon et al. 2013). Finding galaxy cluster candidates at z > 1 in a wide, deep imaging survey data will enable us to solve such issues of modern extragalactic astronomy. We report new candidate galaxy clusters in one of the wide and deep survey fields, the European Large Area ISO Survey North1 (ELAIS-N1) and North2 (ELAIS-N2) fields, covering a sky area of $8.75deg^2$ and $4.85deg^2$ each. We also suggest a new useful color selection technique to separate z > 1 galaxies from low - z galaxies by combining multi-wavelength data.

• 천문학회지
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• 제30권1호
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• pp.1-11
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• 1997

Near infrared JHK magnitudes are presented for two hundred two high proper motion stars. We have observed high proper motion stars in the near-infrared bands(JHK) using the COB detector on the Kitt Peak 1.3m, 2.1m and 4m telescopes. The observations and data reduction procedures are described. The infrared color magnitude diagram and color-color diagrams for the program stars are presented.

• 천문학회보
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• 제32권2호
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• pp.76.2-76.2
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• 2007

• 천문학회보
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• 제31권1호
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• pp.58.2-58.2
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• 2006

• 천문학회보
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• 제32권1호
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• pp.42.1-42.1
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• 2007

• 천문학논총
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• 제11권1호
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• pp.75-90
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• 1996

The vertical distribution of HCN, $HC_3N$ and $C_2N_2$ have been determined from a sequence of Voyager 1 IRIS limb tangent measurements over Titan's north polar region. This sequence yields gas distributions with ${\sim}200\;km$ altitude resolution over the 50-400 km range. The derived mixing ratios of HCN, $HC_3N$ and $C_2N_2$ are $5{\times}10^{-7}$, $7{\times}10^{-8}$ and $8{\times}10^{-9}$, respectively, at 120 km with a factor of 3 uncertainty.