• 천문학논총
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• 제27권3호
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• pp.49-59
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• 2012

KASI (Korea Astronomy and Space Science Institute) has developed an SLR (Satellite Laser Ranging) system since 2008. The name of the development program is ARGO (Accurate Ranging system for Geodetic Observation). ARGO has a wide range of applications in the satellite precise orbit determination and space geodesy research using SLR with mm-level accuracy. ARGO-M (Mobile, bistatic 10 cm transmitting/40 cm receiving telescopes) and ARGO-F (Fixed stationary, about 1 m transmitting/receiving integrated telescope) SLR systems development will be completed by 2014. In 2011, ARGO-M system integration was completed. At present ARGO-M is in the course of system calibration, functionality, and performance tests. It consists of six subsystems, OPS (Optics System), TMS (Tracking Mount System), OES (Opto-Electronic System), CDS (Container-Dome System), LAS (Laser System) and AOS (ARGO Operation System). In this paper, ARGO-M system structure and integration status are introduced and described.

• 천문학회보
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• 제37권2호
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• pp.159.2-159.2
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• 2012

In this study, we propose an effective strategy for precise orbital and geodetic parameter estimation using SLR (Satellite Laser Ranging) observations for ILRS AAC (Associate Analysis Center). The NASA/GSFC GEODYN II software and SLR normal point observations of LAGEOS-1, LAGEOS-2, ETALON-1, and ETALON-2 are utilized for precise orbital and geodetic parameter estimation. Weekly-based precise orbit determination strategy is applied to process SLR observations, and Precise Orbit Ephemeris (POE), TRF (Terrestrial Reference Frame), and EOPs (Earth Orientation Parameters) are obtained as products of ILRS AAC. For improved estimation results, selection strategies of dynamic and measurement models are experimently figured out and configurations of various estimation parameters are also carefully chosen. The results of orbit accuracy assessment of POE and precision analysis of TRF/EOPs for each case are compared with those of existing results. Finally, we find an appropriate strategy for precise orbital and geodetic parameter estimation using SLR observations for ILRS AAC.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2010년도 한국우주과학회보 제19권1호
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• pp.36.2-36.2
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• 2010

Followed the System Design Review (PDR) of a mobile SLR (Satellite Laser Ranging) system, a successful preliminary design review was finished in 2009. With the completion of this mobile SLR system, KASI (Korea Astronomy and Space Science Institute) can perform a series of test observation and calibration/validation procedures. After the operation performance of the whole system reaches the nominal design, a regular scheduled observation will be executed. However, the project has been disturbed by the frequent change of working staff, budget profile, and plan as well as the inexperienced man power. In this study, the contents and the issues of PDR are briefly reviewed and several items of SLR system are suggested. This mobile SLR system will push Korea's Space Geodetic study further and will make us jump to another step to the Space Science in Korea.

• Journal of Astronomy and Space Sciences
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• 제10권2호
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• pp.189-196
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• 1993

상해 천문대 Sheshan 관측소의 레이저 위성거리 측정기기를 이용하여 LAGEOS II위성에 대한 레이저 관측을 수행하여 총 1,838점을 얻었다. 관측된 거리 자료를 지상목표물 관측에 의한 관측기기 지연보정, 대기굴절 보정, 위성의 질량중심거리 보정, 일반 상대론적 보정과 지구 고형체 조석, 극 조석, 대양 조석을 포함한 조석보정을 통해 지연값을 결정하였는데 거리보정의 평균값은 19.12m이다. 결국 다항식 fitting 과 최소 자승법을 이용하여 계산한 관측값의 내부 정밀도 평균은 $\pm$7cm이다. 잡음을 제거하고 보정된 최종 관측점은 1,340점으로 관측점 총수에 대한 잡음비율은 27.1%이다.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2010년도 한국우주과학회보 제19권1호
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• pp.27.5-28
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• 2010

The unexpected observation condition or insufficient measurement modeling can lead to uncertain measurement errors. The uncertain measurement error of orbit determination problem typically consists of noise, bias and drift. It must be removed by using a proper estimation process for better orbit accuracy. The estimation of noise and drift is not easy because of their random or unpredictable variation. On the other hand, bias is a constant difference between the mean of the measured values and the true value, so it can be simply removed. In this study, precision orbit determination with SLR observations considering range bias estimation is presented. The Yonsei Laser-ranging Precision Orbit Determination System (YLPODS) and SLR NP (Normal Point) observations of CHAMP satellite are used for this work. The SLR residual test is performed to estimate the range bias of each arc. The result shows that we can get better orbit accuracy through range bias estimation.

• 한국항공우주학회지
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• 제35권12호
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• pp.1135-1142
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• 2007

과학기술위성2호는 정밀궤도결정을 위하여 위성레이저반사경을 부착할 예정이다. 위성레이저반사경은 지상으로부터 방사된 레이저가 위성에 부착된 반사경으로부터 되반사되어 돌아오는 광자(Photon)의 이동시간을 측정함으로써 관측소와 위성까지의 거리를 정밀하게 측정하는데 사용된다. 현재 레이저반사경은 준비행모델을 개발하였으며, 환경시험을 수행하였다. 본 논문에서는 레이저반사경의 준비행모델의 개발과정을 소개하고, 환경시험 결과를 보고한다. 준비행모델 레이저반사경의 환경시험은 엔지니어링 모델에서 발생하였던 코너큐브프리즘의 파손없이 성공적으로 수행되었다.

• 한국항공우주학회지
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• 제36권1호
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• pp.92-99
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• 2008

다목적실용위성5호는 정밀궤도결정을 위하여 위성레이저반사경을 부착할 예정이다. 레이저반사경은 독일 DFZ에서 개발된 것으로 4개의 코너큐브로 구성된 피라미드 형태를 갖는다. 본 논문에서는 레이저반사경의 유효면적과 link budget에 따른 광자수 계산 및 지상관측소 위치에 따른 광자수 계산 등의 성능 해석을 수행하였다.

• Journal of Astronomy and Space Sciences
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• 제30권1호
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• pp.49-58
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• 2013

ARGO-M is a satellite laser ranging (SLR) system developed by the Korea Astronomy and Space Science Institute with the consideration of mobility and daytime and nighttime satellite observation. The ARGO-M optical system consists of 40 cm receiving telescope, 10 cm transmitting telescope, and detecting optics. For the development of ARGO-M optical system, the structural analysis was performed with regard to the optics and optomechanics design and the optical components. To ensure the optical performance, the quality was tested at the level of parts using the laser interferometer and ultra-high-precision measuring instruments. The assembly and alignment of ARGO-M optical system were conducted at an auto-collimation facility. As the transmission and reception are separated in the ARGO-M optical system, the pointing alignment between the transmitting telescope and receiving telescope is critical for precise target pointing. Thus, the alignment using the ground target and the radiant point observation of transmitting laser beam was carried out, and the lines of sight for the two telescopes were aligned within the required pointing precision. This paper describes the design, structural analysis, manufacture and assembly of parts, and entire process related with the alignment for the ARGO-M optical system.

• 한국측량학회지
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• 제38권6호
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• pp.717-723
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• 2020

VLBI, SLR, DORIS, GNSS와 같은 우주측지기술 사이의 3차원 벡터를 결정하는 작업은 ITRF에 중요한 요소이다. 따라서 각각의 우주측지기술에 해당되는 IVP를 정확하게 계산할 필요가 있다. 본 연구에서는 기존 모델에 비해 업데이트된 수학모델을 사용하여 세종시에 위치한 VLBI의 IVP 위치를 계산함으로써 계산의 효율과 신뢰성을 높였다. 관측값으로는 안테나에 부착된 반사타겟의 좌표가 사용되었으며 이때 관측오차크기는 1.5 mm로 설정하였다. 조정계산을 통해 VLBI IVP 좌표와 정확도를 계산했으며 기존 연구에서 제시한 값과 비교했을 때 성공적으로 계산이 된 것으로 판단된다. 하지만 실제 관측오차가 고려된 VLBI IVP를 계산하기 위해서는 향후 VLBI IVP 계산을 위한 추가적인 지상측량이 필요하다.

• 한국생산제조학회지
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• 제22권5호
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• pp.879-885
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• 2013

Satellites provide a lot of information and essay roles in the areas of defense and space observations. The precise distances to the satellites are measured by emitting and retro-reflecting a laser. For such surveys, satellite laser ranging (SLR) systems have been developed in different forms and for different areas. The structural integrity of the tracking mount is essential for it to be able to track a high-speed satellite precisely, overcoming the various external and internal disturbances and operating conditions. In this study, the analysis of a tracking mount was performed for weight, wind loads, and inertia loads in order to verify its soundness. The results of the comparison between aluminum and steel were analyzed in order to select the optimal material for the fork and main housing part. In addition, the natural frequency and mode shape were predicted. Optimal material selection and structural integrity will also be verified using static analysis.