• International Journal of Aeronautical and Space Sciences
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• v.8 no.1
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• pp.105-114
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• 2007

This article presents the details of a designed control moment gyroscope (CMG) with a constant speed momentum wheel and one-axis-gimbal, and its experimental results performed at Korea Aerospace Research Institute. The CMG which is able to produce a torque of lOO mNm per each, is mounted in a pyramid configuration with four SGCMGs. Each CMG test and a single axis maneuver test with four-CMG cluster configuration are performed to confirm their performance on a ground-test facilities consisted of three major parts: a vibration isolation system, a dynamic force plate (Kistler sensor), and a DSP board. These facilities provide the accurate data of three axial and torques from the control moment gyro. Details of the CMG experimental results are presented with discussion of the experimental errors. The experimental data are compared with theoretical results and both results are used to verify their performance specifications.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1403-1405
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• 2008

In this paper, the preliminary EMC analysis process between the Communication, Ocean and Meteorological Satellite (COMS) and Geostationary Earth Orbit (GEO) launch vehicles in the frequency range [1MHz-47MHz] is described. The considered launch vehicle is the Arian V. The launch vehicle Radiated Emission (RE) specifications have been compared to COMS satellite Radiated Susceptibility (RS) limits. The COMS RS limits are the RS qualification levels of COMS units during launch. As a result, The radiated emission levels of the Arian V is compliant with COMS RS limits.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.8
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• pp.863-869
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• 2015

This study analyzed the offshore plant industry and related regulations such as ISO, IEC, and Norsok Standards to develop an integrated network management system (INMS) capable of both on-site and remote management and configuration of IP-based network equipment in offshore plants. The INMS was designed based on actual specifications and POS plans, and a plan of management was verified through an offshore plant engineering company. Various modules such as PAGA interface modules, CCTV, IP-PBX, and HF-radio communication modules were developed for system implementation. Protocol and data design and screen design were followed by framework development and introduction of the automatic satellite communication function.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.8
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• pp.787-795
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• 2003

Three types of array antennas are developed for broadcasting band of Koreasat III. First, the specification of the array antenna is decided. Second, characteristics and advantages of three types of antennas using the radial waveguide characteristics is investigated and discussed. Third, design method fur those antenna is studied to meet antenna specifications, and then antennas are designed and tested. Finally, it is concluded that these types of antennas can be efficiently design compared to both parabola antennas and microstrip array within the limited size.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.9
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• pp.1001-1009
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• 1992

In this paper, the standard A earth station antenna was designed by using the shaping techniques and also manufactured for I NTELSAT satellite. The designed antenna Is C-band shaped casse grain antenna with the diameter of 18m. The wide-angle radaiation patterns wholly satisfied CCIR Recommendation of sidelobe envelope line of 29-25 logo. The whole radiatlon characteristics satisfied the design specifications.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.11
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• pp.1157-1163
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• 2009

This paper introduces the lithium ion battery management system for STSAT-3 satellite. The specifications of lithium ion battery unit are proposed to supply power to the satellite and the overall electrical design for lithium ion battery BMS is presented. Furthermore, the test results of battery management system are shown to verify the design.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.6
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• pp.522-528
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• 2014

A UHF/VHF full-duplex communication using monopole and dipole antenna has been widely used for cube satellite applications. This kind of communication system requires a dedicated structure panel for antenna integration, which is the one of the disadvantages of the conventional communication system from the accommodation point of view considering the extremely limited volume of the cube satellite. In this study, to maximize the accommodation efficiency of the cube satellite, the commercial UHF half-duplex antenna combined with buck converter for communication modes transition has been considered in the communication system design. Its effectiveness has been verified through link budget analysis based on the antenna specifications and satellite's operation conditions. In addition, the antenna deployment mechanism for the synchronous release of multi-antennas has also been introduced.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.3
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• pp.318-325
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• 2019

As satellite communication technology with high efficiency and spatiality evolves, demands of customer for efficient and effective satellite broadcasting services are increasing due to interval reduction of the between satellites, and the limited radio-frequency spectrum resources. Recently, research on antenna that it possible to simultaneously receive multiple signal from various satellites while holding maintain the same number of previous reception channels by using the single reflector has been ongoing. It is necessary to be able to simultaneously receive signals from various satellites in order to maintain the same number of previous reception channels. We suggest a multiband antenna which can be simultaneously and independently receiving Ku band and Ka band satellite broadcasting signals transmitted by three adjacent satellites. We have designed and simulated using commercial design tools TICRA CHAMP and CST MWS to meet the target specifications. It appears that the antenna has -10 dB return loss, and more than 40 dBi directivity gain in Ku band and Ka band respectively.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1998.06b
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• pp.10-15
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• 1998

In Japan, digital HDTV services via broadcasting satellite are planned to start in 2000. NHK has developed an HDTV codec conforming to the MPEG-2 $MPHL$ and estimated the coded picture quality with diverse image sequences. This paper shows the codec specifications and presents the result of the picture quality assessment.

• Journal of Astronomy and Space Sciences
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• v.32 no.4
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• pp.379-386
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• 2015

This work presents fuel-optimal altitude maintenance of Low-Earth-Orbit (LEO) spacecrafts experiencing non-negligible air drag and J2 perturbation. A pseudospectral (direct) method is first applied to roughly estimate an optimal fuel consumption strategy, which is employed as an initial guess to precisely determine itself. Based on the physical specifications of KOrea Multi-Purpose SATellite-2 (KOMPSAT-2), a Korean artificial satellite, numerical simulations show that a satellite ascends with full thrust at the early stage of the maneuver period and then descends with null thrust. While the thrust profile is presumably bang-off, it is difficult to precisely determine the switching time by using a pseudospectral method only. This is expected, since the optimal switching epoch does not coincide with one of the collocation points prescribed by the pseudospectral method, in general. As an attempt to precisely determine the switching time and the associated optimal thrust history, a shooting (indirect) method is then employed with the initial guess being obtained through the pseudospectral method. This hybrid process allows the determination of the optimal fuel consumption for LEO spacecrafts and their thrust profiles efficiently and precisely.