• Journal of Astronomy and Space Sciences
• /
• v.18 no.3
• /
• pp.239-248
• /
• 2001

Far-ultraviolet IMaging Spectrograph (FIMS) is the main payload of the first Korean scientific satellite, KAISTSAT-4, which will be launched in 2002. Among the optical parts, parabolic cylinder mirror does not have any heritage from previous astronomical missions, so the manufacturing and testing process itself is a challenging issue. We describe the method of manufacturing and measuring of the off-axis parabolic cylinder mirror and our initial experiments to establish the entire manufacturing process. Using the method, the profile error can meet the specification of $lambda$ per cm which is closely related with the astronomical performances. In case of the surface roughness, temperature controlled pitch polishing reduces $R_{q}$ under 1 nm implying that scattering in the entire spectral range of FIMS is less than 2% of the incident UV light.

• The Korean Journal of Air & Space Law and Policy
• /
• v.27 no.1
• /
• pp.123-156
• /
• 2012

This study focuses on the satellite licenses and the requirements for satellite spectrum management (i.e. frequency allocation) in Korean satellite industry via comparative analyses against those cases in other developed countries, in order to provide complementary measures to the domestic satellite policies. The satellite industry is one of the main pursuits of a nation's efforts, and it shows distinct characteristics depending on various factors such as national defense and security. In addition, the industry is determined by the nation's market size as well as its international relationship. Consequently, the present study considers examples from various organizations and nations - including U.S.A, Japan, and ITU - and provides a hybrid policy that is well customized for the domestic market. This study looks at similarities between policies of other countries, and finds any supplements for domestic polices by specifying similar cases in others and analyzing their results. The main purpose of this study, therefore, is to find the best agreement for domestic policy with internal interpretation, rather accepting others. While the licensing method for domestic satellites need not be distinct from that of other nations, the case of using non-Korean licensed satellites must be complemented by the conditions in the domestic market. Furthermore, the spectrum management is essential to the nation's satellite industry since the spectrum is a scarce resource. As such, spectrum management that is carefully designed to incorporate the rapidly changing international market demand is crucial to provide a sufficient supply for domestic space industry. In the present study, we find that auction-like market based approaches together with measures to avoid exclusive uses of the scarce resource (e.g. share, leas and reallocation) would provide an excellent method for the domestic satellite industry.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.48 no.2
• /
• pp.147-158
• /
• 2020

In this paper, we will review the thruster based reaction wheel momentum dumping method for low Earth orbit satellite. Thruster based momentum dumping is widely used in GEO satellites by performing momentum dumping and attitude control using thrusters at the specific time. LEO satellite should perform momentum dumping at any time, thus it is not appropriate to use GEO satellite's momentum dumping method. In this research, we will review the method for LEO satellite, which perform momentum dumping always and use reaction wheels for attitude control during dumping. To reduce thruster's valve on and off counts, we propose to use the maximum pulse width for thruster operation. To prevent attitude error increase by thrusters, we adjust the thruster operation interval. Through simulation, we verify the proposed method's effects.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.5
• /
• pp.1031-1039
• /
• 2016

The Quasi-Zenith Satellite System(QZSS) is the Japanese satellite navigation system, which designs to increase the GPS system's visibility in the urban areas. The first satellite(Michibiki) was launched in 2010 and started to broadcast navigation signals. Therefore, the purpose of the research is to analyze the performance of GPS and QZSS based on the advantage of the integrated GNSS. Especially, the study has been processed in terms of improving satellite navigation parameters around Korean Peninsula. To do this, there have been the comprehensive analysis of the QZSS characteristics, the experimental test, and its statistical analysis for realizing advantage of GPS and QZSS. Through these systemic steps, it was recognized that the integrated GPS and QZSS has more reliable than GPS in case of not only limited visibility but also ordinary positioning. Additionally, the integrated GPS and QZSS would be very useful to improve the various navigation parameters around the peninsula.

• Proceedings of the KSRS Conference
• /
• 2004.10a
• /
• pp.386-388
• /
• 2004

The International Space Station (ISS) offers research opportunities to researchers through crew's space mission in the field of remote sensing. ISS provides the facilities to place and operate experiment equipments in a variety of fields, especially, microgravity experiments and Earth observations. This paper is intended to give readers a brief introduction to the ISS utilization and the capabilities for remote sensing researches. We investigate what kind of crew missions and payloads should be developed for remote sensing researches on the ISS.

• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.1413-1414
• /
• 2003

Interannual variability in the patterns of satellitederived pigment concentrations, sea-level height anomaly, sea surface temperature anomaly, and zonal wind anomaly are observed during the 2002-2003 El Ni${\tilde{n}}$o. The largest spatial extent of the phytoplankton bloom was recovery from El Ni${\tilde{n}}$o over the equatorial Pacific. The evolution towards a warm episode (El Ni${\tilde{n}}$o) started from spring of 2002 and continued during January 2003, while equatorial Sea Surface Temperature Anomaly (SSTA) remained greater than +1$^{\circ}$C in the central equatorial Pacific. The EOS (Earth Observing System) and OSMI (Ocean Scanning Multispectral Imager) data are used for detection of dramatic changes in the patterns of pigment concentration during El Ni${\tilde{n}}$o.

• Journal of Advanced Navigation Technology
• /
• v.21 no.6
• /
• pp.579-584
• /
• 2017

SBAS is a satellite based navigation correction system that provides correction information and integrity information of GNSS signal through geostationary satellite based on analysis of GNSS signal in ground station. KASS, a Korean SBAS, is aiming at the APV-1 class SoL service in 2022. Sufficient ground and flight tests must be performed in advance to provide SoL services. However, since KASS, the Korean SBAS, has not yet been added in Korea, specific detailed evaluation items are not presented. EGNOS, which is expected to be the most compatible with KASS and is being serviced after its development, has already been evaluated. In this paper, we analyze the regulations applied to EGNOS construction and analyze the criteria of ground and flight test evaluation items required for flight testing, which is expected to be referenced to the flight inspection process in the future.

• Journal of Satellite, Information and Communications
• /
• v.8 no.2
• /
• pp.22-28
• /
• 2013

In this paper, new LBS (location based service) are proposed using conventional DMB (digital multimedia/mobile broadcasting) system. LBS applications are proposed that can be suitable for the subway and ground transportation based on S-DMB (satellite-DMB) and T-DMB (terrestrial-DMB) respectively. In the shaded area such as subway, the broadcasting signal transmitted from the satellite of S-DMB system should be retransmitted by the earth repeater called the gap filler and each gap filler has its own identification value called the gap filler ID which introduces the area in which the gap filler was installed. Therefore, the LBS can be implemented by using the gap filler ID of S-DMB on the subway in which the GPS (global positioning system) can't be received. Unlike the LBS on the subway, the combination of T-DMB and DGPS (differential GPS) will be introduced as a way for ground transportation. Generally, DGPS has been designed to compensate the position value calculated from the GPS signal so that positioning error of about 1 meter can be obtained by using DGPS information. T-DMB system transmitting DGPS signal will be expected to be commercial in Korea and, if using DGPS information transmitted through T-DMB network, LBS with more precise positioning than GPS alone can be implemented in the ground vehicles.

• Bulletin of the Korean Space Science Society
• /
• 1995.10a
• /
• pp.37-37
• /
• 1995

No Abstract, See Full Text

• Journal of Satellite, Information and Communications
• /
• v.5 no.2
• /
• pp.97-103
• /
• 2010

In this paper, we present an efficient design scheme based on analysis of design requirements and considerations of baseband packet switch for S-band satellite/terrestrial hybrid multi-beam satellite communication systems. To establish design requirements and considerations, we analyze required functions of baseband packet switch, specifications of multi-beam satellite communications, communication services and performance requirements. And also we analyze and compare conventional layer-2 and layer-3 satellite baseband packet switching techniques, packet switching protocols and packet switch architectures, to apply from analyzed results. Finally, we propose a hardware design scheme of MPEG based layer-2 baseband packet switch using analyzed results.