• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.11
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• pp.1240-1247
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• 2010

This paper describes the study on the electrical design of a multi-beam large antenna for a satellite payload. This satellite antenna provides the universal communication and broadcasting services to personal portable terminals over the Korean Peninsula. The structure of the hybrid antenna fed by a feed array is proper to provide multi-beams. The amplitude and phase of each feed element should be optimized for a required beam and they can be obtained by GO (Geometrical Optics) and PO(Physical Optics) method. The number of feed elements are also optimized to meet the specification of EIRP(Effective Isotropically Radiated Power). The optimally designed antenna with the limited reflector size and minimum number of feed elements is shown in this paper.

• 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 Aerospace System Engineering
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• v.16 no.2
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• pp.1-12
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• 2022

The purpose of this study was to investigate the supply and demand structure of the domestic space industry through analysis of industrial concentration index, by sector and dependence on revenue by customer type. As a result of industrial concentration analysis, in the case of space application, a supply monopoly or oligopoly structure was revealed in fields such as satellite broadcasting, space insurance, and satellite navigation. In the field of space equipment manufacturing, referred to as the traditional space industry, a supply monopoly structure appeared only in the field of launch pads and test facilities. As a result of analyzing the dependence on revenue by customer type, the dependence on the demand in the space application field is diversified among foreign countries, private institutions, and others. However, in the case of space equipment manufacturing, it is highly dependent on the demand of public institutions, and it seems that there is a monopsony structure.

• Korean journal of communication and information
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• v.36
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• pp.374-398
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• 2006

This paper attempts to identify motivations of the satellite DMB use and to examine the relationship between user motivations and structure of genre consumption. Firstly, this paper identified motivational dimensions for satellite DMB usage. The results of the factor analysis revealed three dimensions: information-seeking, entertainment-oriented and social communication. It accounts for 69.9% of the variances found within this data. Secondly, the results of the regression analyses suggested that both information seeking and entertainment-oriented motivations were closely related to genre preferences of satellite DMB contents. In addition, these two motivations predicted genre repertoires and similarity in genre consumption. In conclusion, motivations of the satellite DMB use were the best predictors for explaining the structure of genre consumption.

• Journal of Astronomy and Space Sciences
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• v.38 no.1
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• pp.31-38
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• 2021

In this paper, we present observations of the Space Radiation Detectors (SRDs) onboard the Next Generation Small Satellite-1 (NEXTSat-1) satellite. The SRDs, which are a part of the Instruments for the study of Stable/Storm-time Space (ISSS), consist of the Medium-Energy Particle Detector (MEPD) and the High-Energy Particle Detector (HEPD). The MEPD can detect electrons, ions, and neutrals with energies ranging from 20 to 400 keV, and the HEPD can detect electrons over an energy range from 0.35 to 2 MeV. In this paper, we report an event where particle flux enhancements due to substorm injections are clearly identified in the MEPD A observations at energies of tens of keV. Additionally, we report a specific example observation of the electron distributions over a wide energy range in which we identify electron spatial distributions with energies of tens to hundreds of keV from the MEPD and with energy ranging up to a few MeV from the HEPD in the slot region and outer radiation belts. In addition, for an ~1.5-year period, we confirm that the HEPD successfully observed the well-known outer radiation belt electron flux distributions and their variations in time and L shell in a way consistent with the geomagnetic disturbance levels. Last, we find that the inner edge of the outer radiation belt is mostly coincident with the plasmapause locations in L, somewhat more consistent at subrelativistic energies than at relativistic energies. Based on these example events, we conclude that the SRD observations are of reliable quality, so they are useful for understanding the dynamics of the inner magnetosphere, including substorms and radiation belt variations.

• Korean Journal of Remote Sensing
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• v.39 no.5_4
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• pp.1075-1084
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• 2023

Satellite-derived data is collected by observing the Earth and is used in various fields such as national defense, natural disasters, location-based services, infrastructure, environment, energy, marine, and insurance. This study aims to present the virtuous cycle structure of the satellite information data industry and the business ecosystem model of the industry. As a research method, cases were collected and categorized from the following areas: literature, online, application, and content. The results show that the ecosystem model of the satellite information data industry provides an approach to content services in public and commercial areas, and develops various algorithmic technologies to facilitate content production and services at the level of complex general-purpose technologies. Second, in terms of content typology, satellite information data can be subdivided into monitoring content, urban space monitoring content, and satellite information content. Third, the consumption value of satellite content could be subdivided into informational value, environmental, social and governance (ESG) value, educational value, and content value. In order to expand the global content market, Korea will need to focus on creating an ecosystem for the satellite information industry and discovering differentiated content. It will also need to increase the popularization and accessibility of data to the general public and promote the Korean K-Satellite Information Data Industry ecosystem through government support, policy efforts, and policies such as establishing legal systems, increasing investment, and training human resources.

• Journal of Satellite, Information and Communications
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• v.6 no.1
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• pp.28-31
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• 2011

In this paper, a new set of structural and sacrificial material that is diamond like carbon (DLC)/photoresist for high performance piezoelectric RF-MEMS switches which are actuated in d33 mode is suggested. To avoid curing problem of photoresist sacrificial layer, DLC structure layer is deposited at room temperature by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) method. And lead zirconate titanate (PZT) piezoelectric layer is deposited on structure layer directly at room temperature by rf magnetron sputtering system and crystallized by rapid thermal annealing (RTA) equipment. Particular attention is paid to the annealing of PZT film in order to crystallize into perovskite and the variation of mechanical properties of DLC layer as a function of annealing temperature. The DLC layer shows good performance for structure layer in aspect to Young's modulus and hardness. The fabrication becomes much simpler and cheaper with use of a photoresist.

• Journal of Satellite, Information and Communications
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• v.10 no.4
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• pp.6-11
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• 2015

The ESD(electrostatic discharge) protection performance of PPS(PMOS pass structure) embedded N-type silicon controlled rectifier(NSCR_PPS) device with different GPNS(Gate to Primary $N^+$ Diffusion Space) structure was discussed for high voltage I/O applications. A conventional NSCR_PPS standard device with FPW(Full P-Well) structure and non-CPS(Counter Pocket Source) implant shows typical SCR-like characteristics with low on-resistance(Ron), low snapback holding voltage(Vh) and low thermal breakdown voltage(Vtb), which may cause latch-up problem during normal operation. However, our proposed NSCR_PPS devices with modified PPW(Partial P-Well) structure and optimal CPS implant demonstrate the improved ESD protection performance as a function of GPNS variation. GPNS was a important parameter, which is satisfied design window of ESD protection device.

• Ocean and Polar Research
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• v.30 no.3
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• pp.361-372
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• 2008

A satellite tracked drifter experiment was conducted to observe thermal structure and surface circulation in the northeastern East China Sea. For this experiment, four ADOS buoys, assembled with surface float and thermister chain, were deployed on August 2007 in southern Jeju-do, where the Kuroshio Branch Current is separated from the main stream. Thermal structure in the upper layer of the northeastern East China Sea was successfully observed during the following $1{\sim}3$ months. Strong thermo-haline front in a northeast-southwest direction was observed. In the frontal zone, warm and saline Kuroshio origin water intermixes with fresher coastal water and flows toward the Korean Strait. Typhoon Nari, which passed over the East China Sea 20 days after commencement of study, caused distinct signals in the thermal structure and trajectory of buoys. During the typhoon, surface temperature abruptly dropped to about $4^{\circ}C$, while the thermocline formed at $30{\sim}50$ m depth vanished due to strong vertical mixing. Internal inertial oscillation occurred several days after the typhoon. The fortuitous occurrence of typhoon Nari showed that ADOS buoys can provide useful and accurate air-sea interaction data during typhoons.

• Journal of Satellite, Information and Communications
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• v.4 no.1
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• pp.1-7
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• 2009

As the information age comes out, the aspect of future war brings about the many changes in terms of war-fighting environment. Accordingly, information superiority and intelligence-centric warfare have been important and new war-fighting concept such as NCW(network centric warfare) have been turned up. This paper proposed all-weather core-strategy communications systems guaranteeing not only the real-time transmission of the information collected in a battlefield and expansion, automation, and rapidity of a battlefield but also broadband, mobility, survivability, and flexibility. The proposed military satellite communications system is classified into wideband mass capacity link, survivability, and the system supporting OTM(on the move) communication for the real-time transmission of battlefield information. This paper analyzed the essential operation concepts and core schemes of the U.S. Army's next generation system, TSAT(Transformational Satellite Communication System). Base on the analysis results, this paper proposed that the architecture of next generation military satellite communications systems for NCW have to provide the data rate, anti-jamming capability, network control and management capability which are optimally adaptable for the wireless channel environments such as jamming and interference and to support the variety of platforms like high-speed mobile vehicles, micromini devices, super-high speed unmanned aerial vehicles. Finally, this paper also proposed that next generation military satellite communications systems need the technologies such as the adaptable multi-antenna, laser link, and next-generation anti-jamming waveform.