• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• 제39권6호
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• pp.477-482
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• 2021

The integrated underground space map system provides information on infrastructure that requires security, but to prevent rupture accidents during excavation work at the underground construction site, it must provide information on all underground facilities on the site. Providing additional information other than the object of interest to the user is a factor that increases the risk of information leakage of security data. In this paper, we design the visualization filtering method that when visualizing the integrated underground space map in the field, the visualization of entire underground facilities of interest to workers is performed, but visualization of other underground facilities is minimized to minimize the risk of security data information leakage. To this end, a visualization area of a certain distance for each of the underground facilities of interest was created, and an integrated visualization filter was created with spatial union operation. When the integrated underground map is output on the screen, only the objects located within the filter area are visualized using the generated filter information, and objects that exist outside are not visualized, thereby minimizing the provision of information to the user.

• Proceedings of the International Union of Geodesy And Geophysics Korea Journal of Geophysical Research Conference
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• IUGG한국위원회 2003년도 정기총회 및 학술발표회
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• pp.14-14
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• 2003

SAR (Synthetic Aperture Radar) is an imaging radar which can scan and image Earth System targets without solar illumination. Most Earth observation Shh systems operate in X-, C-, S-, L-, and P-band frequencies, where the shortest wavelength is approximately 1.5 cm. This means that most opaque objects in the SAR signal path become transparent and SAR systems can image the planetary surface targets without sunlight and through rain, snow and/or even volcanic ash clouds. Most conventional SAR systems in operation, including the Canada's RADARSAT-1, operate in one frequency and in one polarization. This has resulted in black and with images, with which we are familiar now. However, with the launching of ENVTSAT on March 1 2002, the ASAR system onboard the ENVISAT can image Earth's surface targets with selected polarimetric signals, HH+VV, HH+VH, and VV+HV. In 2004, Canadian Space Agency will launch RADARSAT-II, which is C-band, fully polarimetric HH+VV+VH+HV. Almost same time, the NASDA of Japan will launch ALOS (Advanced land Observation Satellite) which will carry L-band PALSAR system, which is again fully polarimetric. This means that we will have at least three fully polarimetric space-borne SAR system fur civilian operation in less than one year. Are we then ready for this new all weather Earth Observation technology\ulcorner Actual imaging process of a fully polarimetric SAR system is not easy to explain. But, most Earth system scientists, including geologists, are familiar with polarization microscopes and other polarization effects in nature. The spatial resolution of the new generation of SAR systems have also been steadily increased, almost to the limit of highest optical resolution. In this talk some new applications how they are used for Earth system observation purpose.

• Bulletin of the Korean Space Science Society
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• 한국우주과학회 2011년도 한국우주과학회보 제20권1호
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• pp.21.4-22
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• 2011

IVS (International VLBI Service for Geodesy and Astrometry) 통합분석센터는 개별 IVS 분석센터의 산출물을 통합하고 그 결과물을 IERS (International Earth Rotation and Reference Systems Service)에 제공하여 국제 지구기준좌표계를 구축하고 지구회전파라미터를 결정하는데 핵심적인 역할을 한다. 한국천문연구원(KASI)은 2008년 10월 IVS 통합분석센터로 선정되어 현재 통합 분석 시스템을 구축하고 있다. 정규운영에 앞서 통합용 분석 소프트웨어를 정비하고, KASI 통합분석센터의 통합해를 타 IVS 통합분석센터 통합해와 비교 검증하는 것은 필수적이다. 이 연구에서는 통합분석처리를 위해서 GPS 자료처리 소프트웨어인 Bernese 5.0을 IVS 산출물 형식에 맞추어 수정 보완한 후 활용한다. 이 발표에서는 1984년부터 현재까지의 IVS 분석센터의 장기간 산출물을 수집하고 Bernese 5.0을 이용하여 지구회전파라미터(X-극, Y-극, UT1-UTC와 각각의 시간변화율)의 통합해를 산출한 결과를 소개한다. 또한, 타 IVS 통합분석센터의 통합해와 비교 검증결과를 논한다.

• Bulletin of the Korean Space Science Society
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• 한국우주과학회 2009년도 한국우주과학회보 제18권2호
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• pp.41.1-41.1
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• 2009

한국천문연구원은 2008년 10월 IVS(International VLBI Service for Geodesy and Astrometry) 통합분석센터로 선정되어 현재 정규운영을 위한 준비 작업을 진행하고 있다. IVS 통합분석센터는 개별 IVS 분석센터에서 산출한 산출물을 통합하여 개별 분석 센터 산출물의 품질을 검증하고 국제 지구기준좌표계 구성에 필요한 입력 데이터를 제공하는 기능을 한다. 이 연구에서는 IVS통합분석센터로서의 역할과 향후 IVS 통합분석센터의 운영계획에 대해 초점을 맞춘다. VLBI 산출물 통합을 위해 다른 IVS 통합분석센터와 차별화하여 GPS 자료처리 소프트웨어 Bernese 5.0에서 제공하는 정규방정식 단계 통합 프로그램인 ADDNEQ2를 활용할 계획이다. 이와 관련하여 VLBI 데이터 처리에 적합하도록 ADDNEQ2를 수정 보완한 사항과 수정된 ADDNEQ2로 통합한 예비 결과에 대해 집중적으로 논의한다. 이와 더불어 산출한 예비 결과를 각 개별 IVS 분석센터 산출물을 바탕으로 비교 검증한 결과를 소개한다.

• Korean Journal of Remote Sensing
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• 제21권1호
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• pp.15-29
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• 2005

Superconducting Gravimeters (SG) are the most sensitive instruments for measuring temporal gravity variations. The gravimeter is an integrating sensor therefore the gravity variations caused by different sources must be separated for studying a special effect by applying different models and data analysis methods. The present reduction methods for gravity variations induced by atmosphere and hydrosphere including the ocean and the detection and determination of the most surface gravity effects are shown. Some examples demonstrate the combination of ground (SG) and space techniques especially the combination of SG with GRACE satellite derived temporal gravity variations. Resulting from the performance of the SG and the applied data analysis methods some proposals are made for future SG applications.

• Journal of Astronomy and Space Sciences
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• 제24권4호
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• pp.417-430
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• 2007

The selection of ground stations is one of the essential process of IGS (International GNSS Service) products. High quality GPS data should be collected from the globally distributed ground stations. In this study, we investigated an effect of ground station network selection on GPS satellite ephemeris. The GPS satellite ephemeris obtained from the twelve ground station networks were analyzed to investigate the effect of selection of ground stations. For data quality check, the observations, the number of cycle slips, and multipath of pseudoranges for L1 and L2 were considered. The ideal network defined by Taylor-Karman structure and SOD (Second Order Design) were used to obtain the optimal ground station network.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• 제21권4호
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• pp.301-308
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• 2003

This study describes the methodology that improves the accuracy of the 3D object-space data extracted from IKONOS satellite images by improving the accuracy of a RPC(Rational Polynomial Coefficient) model. For this purpose, we developed the algorithm to adjust a RPC model, and could improve the accuracy of a RPC model with this algorithm and geographically well-distributed GCPs(Ground Control Points). Furthermore, when a RPC model was adjusted with this algorithm, the effects of geographic distribution and the number of GCPs on the accuracy of the adjusted RPC model was tested. The results showed that the accuracy of the adjusted RPC model is affected more by the distribution of GCPs than by the number of GCPs. On the basis of this result, the algorithm using pseudo_GCPs was developed to improve the accuracy of a RPC model in case the distribution of GCPs was poor and the number of GCPs was not enough to adjust the RPC model. So, even if poorly distributed GCPs were used, the geographically adjusted RPC model could be obtained by using pseudo_GCPs. The less the pseudo_GCPs were used -that is, GCPs were more weighted than pseudo_GCPs in the observation matrix-, the more accurate the adjusted RPC model could be obtained, Finally, to test the validity of these algorithms developed in this study, we extracted 3D object-space coordinates using RPC models adjusted with these algorithms and a stereo pair of IKONOS satellite images, and tested the accuracy of these. The results showed that 3D object-space coordinates extracted from the adjusted RPC models was more accurate than those extracted from original RPC models. This result proves the effectiveness of the algorithms developed in this study.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제44권12호
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• pp.1103-1111
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• 2016

Korea Astronomy and Space Science Institute (KASI) has been operating SLR (Satellite Laser Ranging) system with 2kHz repetition rate for satellite precise orbit and spin determination as well as space geodesy. But the SLR system was improved to be capable of laser ranging with high repetition rate, up to 10kHz by developing new operation software and novel range gate generator, called HSLR-10. The HSLR-10 will contribute to the accurate spin rate determination of geodetic satellites and geodetic research due to its largest repetition rate in the world. In this study, the development methodology and configuration of operation software are addressed, and its validation results are also presented.

• Journal of Astronomy and Space Sciences
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• 제30권4호
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• pp.315-320
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• 2013

Space geodetic techniques can be used to obtain precise shape and rotation information of the Earth. To achieve this, the representative combination solution of each space geodetic technique has to be produced, and then those solutions need to be combined. In this study, the representative combination solution of very long baseline interferometry (VLBI), which is one of the space geodetic techniques, was produced, and the variations in the position coordinate of each station during 7 years were analyzed. Products from five analysis centers of the International VLBI Service for Geodesy and Astrometry (IVS) were used as the input data, and Bernese 5.0, which is the global navigation satellite system (GNSS) data processing software, was used. The analysis of the coordinate time series for the 43 VLBI stations indicated that the latitude component error was about 15.6 mm, the longitude component error was about 37.7 mm, and the height component error was about 30.9 mm, with respect to the reference frame, International Terrestrial Reference Frame 2008 (ITRF2008). The velocity vector of the 42 stations excluding the YEBES station showed a magnitude difference of 7.3 mm/yr (30.2%) and a direction difference of $13.8^{\circ}$ (3.8%), with respect to ITRF2008. Among these, the 10 stations in Europe showed a magnitude difference of 7.8 mm/yr (30.3%) and a direction difference of $3.7^{\circ}$ (1.0%), while the 14 stations in North America showed a magnitude difference of 2.7 mm/yr (15.8%) and a direction difference of $10.3^{\circ}$ (2.9%).

• Proceedings of the KSRS Conference
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.87-90
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• 2005

The FORMOSAT-3/COSMIC mission is a micro satellite mission to deploy a constellation of six micro satellites at low Earth orbits. The final mission orbit is of an altitude of 750-800 lan. It is a collaborative Taiwan-USA science experiment. Each satellite consists of three science payloads in which the GPS occultation experiment (GOX) payload will collect the GPS signals for the studies of meteorology, climate, space weather, and geodesy. The GOX onboard FORMOSAT -3 is designed as a GPS receiver with 4 antennas. The fore and aft limb antennas are installed on the front and back sides, respectively, and as well as the two precise orbit determination (POD) antennas. The precise orbit information is needed for both the occultation inversion and geodetic research. However, the instrument associated errors, such as the antenna phase center offset and even the different cable delay due to the geometric configuration of fore- and aft-positions of the POD antennas produce error on the orbit. Thus, the focus of this study is to investigate the impact of POD antenna parameter on the determination of precise satellite orbit. Furthermore, the effect of the accuracy of the determined satellite orbit on the retrieved atmospheric and ionospheric parameters is also examined. The CHAMP data, the FORMOSAT-3 satellite and orbit parameters, the Bernese 5.0 software, and the occultation data processing system are used in this work. The results show that 8 cm error on the POD antenna phase center can result in ~8 cm bias on the determined orbit and subsequently cause 0.2 K deviation on the retrieved atmospheric temperature at altitudes above 10 lan.