• Title/Summary/Keyword: Small satellite

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Estimation of Small Reservoir Storage Using Sentinel-1 Image (Sentinel-1 위성영상을 활용한 소규모 저수지 저수량 추정)

  • Jang, Moon-Yup;Song, Ju-Il;Jang, Cho-Rok;Kim, Han-Tae
    • Journal of the Society of Disaster Information
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    • v.16 no.1
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    • pp.79-86
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    • 2020
  • Purpose: In this study, a model was developed to estimate the storage in Cheonan reservoir using images taken by Sentinel-1 satellite. Method: A total of three reservoirs were studied. All three reservoirs are small reservoirs whose water level is being measured. The preprocessing of Sentinel-1 images was done using SNAP distributed by the European Space Agency(ESA), and the storage was estimated by classifying water surface by the threshold classification method. The estimated reservoir area was compared with satellite and drones images taken on the same day. The correlation was derived by comparing the estimated reservoir area with the actual measurement. Results and Conclusions: The storage values estimated by satellite image analysis showed similar values to the actual measurement data. However, because of the underestimation of the reservoir area due to green algae and Epilithic diatom of summer reservoirs and the low resolution of satellite images, it is dificult to detect reservoir area by satellite images less than 10,000㎡.

Spectrum and Equivalent Transient Vibration Analysis of Small Composite Satellite Structure (소형 복합재위성의 스팩트럼 및 과도진동해석)

  • Cho, Hee-Keun;Seo, Jung-Ki;Myung, Noh-Hoon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.6
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    • pp.586-594
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    • 2009
  • This paper is the study on random, sinusoidal and shock vibration responses for the STSAT-3(science and technology satellite-3) proto-model which is the first small size all-composite satellite in Korea. The structure system of the STSAT-3 forms box type structure by joining several hybrid sandwich panels comprised of honeycomb core and carbon fiber reinforced laminated composite skins on both side. Mode shape, stress, displacement and acceleration responses are obtained on both the frequency domain and time domain by means of a commercial FEA software MSC/NASTRAN. From these analysis results, failure, safety factor and design validity are assessed. These results can be successfully applicable as reference data when a new satellite is developed as well as giving out an excellent criteria in satellite vibration treatment design.

Fabrication and Performance Test of Small Satellite Camera with Focus Mechanism (포커스 메커니즘이 적용된 소형 위성 카메라의 제작 및 성능 실험)

  • Hong, Dae Gi;Hwang, Jai Hyuk
    • Journal of Aerospace System Engineering
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    • v.13 no.4
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    • pp.26-36
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    • 2019
  • The precise alignment between optical components is required in high-resolution earth observation satellites. However, the misalignment of optical components occurs due to external factors such as severe satellite launch environment and space environment. A satellite optical system with a focus mechanism is required to compensate for the image quality degraded by these misalignments. This study designed, fabricated, aligned precisely, and carried out a performance tests for the image quality of the system. The satellite optical camera performance tests were carried out to check the image quality change by operating the focus mechanism and to analyze the satellite optical system MTF by photographing USAF target using the autocollimator. According to the experimental results, the misalignments can be compensated sufficiently with the focus mechanism. Finally the basic data for re-focusing algorithm of the optical system was obtained through this study.

A DESIGN OF SMALL DATA UTILIZATION SYSTEM FORTHECOMS

  • Seo Seok-Bae;Ku In-Hoi;Kang Chi-Ho;Lirn Hyun-Su;Ahn Sang-IL
    • Proceedings of the KSRS Conference
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    • 2005.10a
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    • pp.268-271
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    • 2005
  • COMS (Communication, Ocean, and Meteorological Satellite) will be launch at end of year 2008. For receiving of COMS LRlT, KARl (Korea Aerospace Research Institute) finished design and software realization of COMS SDUS (Small Data Utilization System). SDUS is a small station receiving LRlT data for distribute satellite image, weather information, and so on. For the future project, KARl preparing COMS MDUS (Mass Data Utilization System) that can receiving large size of data over than 2M BPS (Bit Per Seconds) data size.

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DCM Analysis of Solar Array Regulator for LEO Satellites (저궤도 인공위성용 태양전력 조절기의 전류 불연속 모드 해석)

  • Park, Heesung;Cha, Hanju
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.4
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    • pp.593-600
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    • 2016
  • The solar array regulator for low earth orbit satellites controls a operating point of solar array for suppling electric power to the battery and the other units. Because the control object is reversed, the new approach for large and small signal analysis is needed despite using buck-converter for power stage. In this paper, the steady state analysis of solar array regulator is performed in continuous conduction mode and discontinuous conduction mode, and the border condition for each mode is established. Also, the small signal model of solar array regulator is established in discontinuous conduction mode. Experiments are carried on in worst condition which the solar array regulator can face with discontinuous conduction mode. The results show that the solar array regulator is in stable.

Staging and Injection Performance Analysis of Small Launch Vehicle Based on KSLV-II (한국형발사체에 기반한 소형발사체의 스테이징 및 투입성능 분석)

  • Jo, Min-Seon;Kim, Jae-Eun;Choi, Jeong-Yeol
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.49 no.2
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    • pp.155-166
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    • 2021
  • In this paper, design study of a small two-stage launch vehicle is undertaken for the dedicated launch of the Compact Advanced Satellite 500 (CAS500)-class satellite into the Low Earth Orbit (LEO) by modifying the second and third stages of the Korean Space Launch Vehicle II (KSLV-II). Since the KSLV-II has three stages, velocity increment is newly distributed for the two-stage small launch vehicle. For this end, the staging design is carried out for the design parameters such as stage mass ratios, structural coefficients and engine options for each stage followed by trajectory analysis. Investigation of the results provides the combination of design parameters for the small launch vehicle for the dedicated launch of 500 kg-class satellite into LEO.

Development of Navigation Computer for Small Satellites Using Integrated GPS/INS (소형위성용 GPS/INS 통합 항법 컴퓨터 개발)

  • Choi, Young-Hoon;Lee, Byung-Hoon;Chnag, Young-Keun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.36 no.4
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    • pp.393-398
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    • 2008
  • This paper suggests a GPS/INS navigation computer architecture that can be applied to small satellites. In order to implement a GPS/INS navigation system on a small satellite, the extreme environment in space such as radiation, micro-gravity, vacuum, etc. must be considered. In addition, a real-time processing ability is required for the GPS/INS navigation system since the formation flying of multiple small satellites is the ultimate goal. The developed navigation electronics utilizes a PowerPC-type MPC860T that has space environment heritage, and a pair of Atmega128s that has been implemented in KAUSAT-2 and has completed the space environment verification tests. The navigation algorithm is designed to work in VxWorks environment, ported in MPC860T.

Critical Conduction Mode BOOST Type Solar Array Regulator (임계모드 부스트형 태양전력 조절기)

  • Yang, JeongHwan;Ryu, SangBurm;Yun, SeokTeak
    • Journal of Satellite, Information and Communications
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    • v.9 no.3
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    • pp.86-90
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    • 2014
  • A DC-DC Converter operates in CCM(Continuous Coundcution Mode), DCM(Discontinuous Conduction Mode), CRM(Critical Conduction Mode). The CRM is boundary between CCM and DCM. If a DC-DC converter is designed to operate in CRM, its inductor volume can decrease and power loss which caused by switch and diode can decrease. In this paper, the DC-DC converter which operates in CRM is applied to a solar array regulator(SAR) for the satellite. The switching frequency of the CRM boost SAR changes according to input and output condition. The switching frequency limit logic is applied to limit the maximum switching frequency. Meanwhile, the small signal transfer function of the CRM boost SAR is simple, so the controller design is also simple. In this paper, the small signal transfer function from control reference to solar array voltage is induced. And the voltage controller is designed based on the small signal transfer function. Finally, the CRM boost SAR is verified by simulation.

Development of 0.6Nm Small CMG Hardware and Performance Test (0.6Nm급 소형 CMG 하드웨어 개발 및 성능시험)

  • Jang, Woo-Young;Rhee, Seung-Wu;Kwon, Hyoek-Jin
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.38 no.9
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    • pp.933-942
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    • 2010
  • Control Moment Gyro(CMG) is one of the most efficient momentum exchange devices for satellite attitude control and CMG is very essential device for agile satellite. And the studies of CMG development and its application to satellite have been done extensively. In this study, the development process of SGCMG hardware for agile small satellite system, the developed hardware and its performance test results are presented. As a SGCMG test results, it is verified that the developed hardware model can produce torque more than 0.6Nm as is designed. By investigating its test data results, the issues that should be considered for the performance improvement and its application are discussed. The remedies for the identified issues are proposed for future study.

Reliability Analysis with Space Radiation of Low-Cost COTS Small Satellite (우주방사능 효과를 고려한 저가 COTS 소형위성의 신뢰성 분석)

  • Jeong, Ji-Wan;Jang, Yeong-Geun;Mun, Byeong-Yeong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.2
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    • pp.56-67
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    • 2006
  • The reliability and failure mode effect analysis are effective means to achieve efficient and cost-reduction design for satellite development. The failure rate of COTS (Commercial-Off-The-Shelf) parts required for reliability analysis is not usually provided from the manufacturer. Space environment factors based on empirical data obtained from MIL-HDBK-217F can be applicable to the reliability calculation. As a radiation environment factor, the occurrence rate of SEL (Single Event Latch-up) is additionally incorporated for the failure rate prediction. In this paper, the statistical reliability analysis method for low-cost small satellite using COTS parts is suggested. This statistical reliability analysis was applied to HAUSAT-2 small satellite whose electronic boxes are consisted of many COTS parts to calculate the system reliability at the end of design mission life.