• Title/Summary/Keyword: SPACE code

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Trend of Space Development and Issue (우주개발동향과 주요 이슈)

  • Cho, Hong-Je;Shin, Yong-Do
    • The Korean Journal of Air & Space Law and Policy
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    • v.29 no.1
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    • pp.97-126
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    • 2014
  • October 4, 1957 the Soviet Sputnik 1 was launched into space the first time in the history of mankind. After launching, the realm of humankind was expanded to space. Today all countries of the world wage a fierce competition in order to utilize space for various purposes. World powers of space such as United States, Russia, China, and Japan, put reconnaissance satellites and ocean surveillance satellites into orbit, being able to easily see equipment and troops movement on earth. Each country makes efforts to occupy space assets through the militarization of space and expand national interests. Recently private companies or individuals involved in commercial space activities are becoming more prevalent. Thus, in addition to space activities for military purposes, commercial space activities become widespread. Individuals and private companies as well as nations are also involved in space activities. Outer space is not the monopoly of space powers such as the United States and Russia. The whole human race can benefit from free access to space, being the common heritage of mankind. In particular, outer space becomes an indispensable element of military activities and human life. Many countries are now entering space development, putting a lot of budget into new development programs. Republic of Korea also built the Narodo Space Center, starting its space development with budget and manpower. We have to find out ways to use space not only for military purposes but also for commercial space activities that can contribute to the national economy. In addition, through the joint efforts of the international community, we have to make efforts for preservation and peaceful use of space. Various issues relating to space activities and research should be studies in order to contribute to the progress of humanity. Those issues include the definition of outer space, space debris reduction and environmental conservation issues, non-bind measure cooperation - European International Code of Conduct, space law and national legislation related empowerment issues, arms control measures in space, and restrictions on the use of nuclear fuel. We also need to be involved in the discussion of those issues as one of responsible space countries. In addition, we try to find out regional cooperation schemes such as the ESA in the Europe actively. Currently in the Northeast Asia, cooperation bodies led by Japan and China respectively, are operated in the confrontational way. To avoid such confrontation, a new cooperative body needs to be established for cooperation on space exploration and information. The system to allow the exchange of satellite information for early warning of natural disasters needs to be built as well. In addition, efforts to enhance the effectiveness of the relevant international treaties on space, and fill in the blanks in international space laws should be made at the same time. To this end, we have to do a leading role in the establishment of standards such as non-binding measures (resolution) - Code of Conduct, being discussed in the UN and other organizations, and compliance with those standards. Courses in aerospace should be requires in law schools and educational institutes, and professional manpower need to be nurtured. In addition, the space-related technology and policy needs to be jointly studied among the private, public, and military groups, and the cross exchange among them should be encouraged.

Study on the Applications of Automatic Differentiation in Engineering Computation (자동 미분의 공학 계산 적용 연구)

  • Lee, Jae-Hun;Im, Dong-Kyun;Kwon, Jang-Hyuk
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.36 no.7
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    • pp.634-641
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    • 2008
  • Automatic Differentiation(AD) is a tool for generating sensitivities, such as gradient or Jacobian, automatically. AD tools provide mathematically exact sensitivities for the given source code. In this paper applications of automatic differentiation are studied. Derivative codes are generated with AD tools for structural analysis code and flow analysis code. How to apply AD tools is explained and the accuracy of sensitivities is compared with the finite difference. Sensitivities of generated derivative code accord well with finite difference, but the calculation time of derivative code increases. It was found that the calculation time can be decreased by additional modification of derivative code.

Simulations of nonlinear field line resonances

  • Kim, Kyung-Im;Lee, Dong-Hun;Kim, Jong-Soo
    • Bulletin of the Korean Space Science Society
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    • 2008.10a
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    • pp.23.3-23.3
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    • 2008
  • In this study, the nature of nonlinear field line resonances (FLR) is studied by adopting full MHD simulations. The MHD code used here is based on the total variation diminishing (TVD) scheme and we have performed numerical simulations of FLR with its three-dimensional code. If the source perturbation is strongly impulsive and thus the timescale of the initial variations is sufficiently smaller than the convection timescale, FLRs are easily confirmed in these simulations. When the disturbance is sufficiently small, it is shown that linear properties of MHD wave coupling are well reproduced. In order to examine nonlinear nature of FLR, wave spectra, Poynting flux and energy distribution are studied at resonances as the magnitude of initial disturbance gradually increases.

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The Latest Performance of Galileo Kinematic PPP at DAEJ Reference Station in South Korea

  • Choi, Byung-Kyu;Yoo, Sung-Moon;Roh, Kyoung-Min;Park, Pilho;Park, Jong-Uk
    • Journal of Positioning, Navigation, and Timing
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    • v.9 no.1
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    • pp.15-21
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    • 2020
  • In October 2019, the European Galileo navigation system operates a total of 24 satellites, two of them are in the testing phase. There are enough satellites in operation to enable precise point positioning (PPP) using Galileo signals. The number of visible satellites for Galileo in South Korea is investigated. In addition, to assess the latest performance of the Galileo kinematic PPP, data received at DAEJ reference station from October 1 to October 7, 2019, are analyzed. Galileo kinematic PPP presents some results in two categories, single-frequency PPP (SPPP) and dual-frequency PPP (DPPP). The positioning accuracy for Galileo kinematic SPPP solutions is less than 1 m root mean square (RMS) in all direction components. The Galileo kinematic DPPP achieves the positioning accuracy with an RMS value of less than 7 cm in all direction components. The results show that the latest performance of Galileo kinematic PPP at DAEJ station in South Korea is still relatively poor compared to GPS kinematic PPP. However, the residuals of Galileo code measurements are smaller than those of GPS code measurements.

Comparative Analysis on Korea-U.S. space policy system (한미간 우주정책 체계 비교분석)

  • HWANG, Chin Young;LEE, Joon
    • Journal of Aerospace System Engineering
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    • v.15 no.1
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    • pp.1-6
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    • 2021
  • U.S contains the best technology, man power, and big investment in space. It considers space as not only a science and technology related area, but also as an industry and national security related area. Korea's space policy focuses on the development of space systems such as satellites and launch vehicles. Space policy systems of the two countries are also different, causing some discrepancy in mutual interest when we talk about cooperation with the U.S. This study introduced U.S space policy framework and compared it with Korea's policy. It is meaningful in that we can find an effective way of cooperation between two countries.

An Optimized Double-ABBA Quasi-Orthogonal Space Time Code with PIC Group Decoding (PIC 그룹 복호화를 이용한 최적화된 Double-ABBA 유사 직교 시공간 부호)

  • Hanif, Mohammad Abu;Lee, Moon Ho;Park, Ju Yong
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.1
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    • pp.21-26
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    • 2013
  • In this paper we propose a system where we divide the group with 2 symbols. The two added symbols are separated by multiplexing and later added using the DE-multiplexing technique. In our proposed system a simple Partial Interference Cancelation (PIC) group decoding scheme is used for Double-ABBA(D-ABBA) Quasi-Orthogonal Space Time Code, which reduces the decoding complexity for the higher order Multiple Input Multiple Output (MIMO) space time block coding. Finally we compare the proposed scheme performance using the different modulation schemes.

Assessment of a Low Power Offset BPSK Component for Spreading Code Authentication

  • Maier, Daniel S.;Pany, Thomas
    • Journal of Positioning, Navigation, and Timing
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    • v.9 no.2
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    • pp.43-50
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    • 2020
  • In this paper a low power Spreading Code Authentication (SCA) sequence with a BPSK(1) modulation at a frequency offset of +7.161 MHz is tested for authentication purposes, the Galileo E1OS is used as base signal. The tested signals comprise a Galileo constellation with 5 satellites including the Galileo OS Navigation Message Authentication (OSNMA) and a low power offset BPSK (OBPSK(7,1)) as SCA component. The signals are generated with the software based MuSNAT-Signal-Generator. The generated signals were transmitted Over-The-Air (OTA) using a Software-Defined-Radio (SDR) as pseudolite. With a real-environment-testbed the performance of the SCA in real channel conditions (fading and multipath) was tested. A new SCA evaluation scheme is proposed and was implemented. Under real channel conditions we derive experimental threshold values for the new SCA evaluation scheme which allow a robust authentication. A Security Code Estimation and Replay (SCER) spoofing attack was mimicked on the real-environment-testbed and analyzed with the SCA evaluation scheme. It was shown that the usage of an OBPSK is feasible as an authentication method and can be used in combination with the OSNMA to improve the authentication robustness against Security SCER attacks.

Performance Comparison of SFBC/SFTC-OFDM Systems Under MB-OFDM Interference (MB-OFDM UWB 신호 간섭하에서 SFBC/SFTC-OFDM 시스템들의 성능 비교)

  • Kim, Kyung-Seok;Song, Chang-Kun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.10A
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    • pp.968-975
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    • 2006
  • Research about the mode of MIMO that can get a coding benefit at the same time with a diversity benefit using a multiple antenna at the fading channel for a high-speed data transmission have been processed actively But the analysis about the interference of UWB system comes not to consist yet. So this paper analyzed the performance of the interference of UWB system to SFBC-OFDM and SFTC-OFDM system that applied a space block code which has a space diversity characteristic to OFDM system at MIMO channel. We shelved the performance that SFTC-OFDM system is robuster than SFBC-OFDM system under MB-OFDM UWB Interference.