研究者詳細 - 趙　孟佑

論文 - 趙　孟佑

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Mission results of high voltage technology demonstration satellite "HORYU-2 査読有り

Iwai S., Khan A., Masui H., Iwata M., Toyoda K., Cho M.

Proceedings of the International Astronautical Congress, IAC 12 9377 - 9391 2013年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The World's largest spacecraft bus voltage is the International Space Station (ISS) with a bias voltage of 160V. We have investigated a power bus able to handle higher voltage than the ISS. Electro-static discharges (ESDs) are more likely to occur when a satellite generates power at a high voltage rather than low voltage in low Earth orbit (LEO). However, high voltage generation is essential for building large space systems. Therefore, Kyushu Institute of Technology (Kyutech) is developing a high voltage generation technology that could counteract ESDs. This could be considered as a key technology for next generation spacecraft. Nano-satellites are useful and less risky tools for technology demonstration since they are faster and less expensive to develop than large satellites. Therefore, we focused on nano-satellite development to demonstrate Kyutech's advanced high voltage generation technology. All of the on-orbit high voltage tests have been demonstrated by using a DC/DC converter to adapt the high voltage generated by the solar array. This was a World premiere as no high voltage tests had previously been performed in space using solar arrays. To demonstrate the feasibility of on-orbit high voltage generation, we developed a High Voltage Technology Demonstration Satellite named HORYU-2. The mission consisted of 300V generation without causing arcing, and contribution to the practical development of 1MW class spacecraft. On May 18, 2012, HORYU-2 was launched by the H-2A rocket number 21. HORYU-2 has been operated from Kyutech's ground station, and HORYU-2's orbit was confirmed and the mission successful. For the first time in the World, 350V have been generated on-orbit without arc creation. Using two specially designed solar arrays arcing was mitigated. Regarding the sub-missions, ELF was proven to work well on-orbit, Trek measurements are currently under investigation, the SCAMP camera successfully imaged Earth, and the debris sensor has not yet detected debris impact. During the conference, we will present all mission analysis in further detail. Copyright ©2013 by the International Astronautical Federation.

Scopus

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Initial results from Primary Arc effects on solar cells at LEO (PASCAL) flight experiment 査読有り

Likar J., Okumura T., Iwai S., Stone S., Gasner S., Jenkins P., Trautz K., Cho M., Lombardi R., Toyoda K.

Conference Record of the IEEE Photovoltaic Specialists Conference 3112 - 3114 2013年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Repeated low power, or primary arcing, may adversely affect the performance of space solar cells. The cumulative effects of primary arcing on common solar cell performance parameters has been the subject of numerous ground studies in simulated plasma environments. The Primary Arc effects on Solar Cells At LEO (PASCAL) flight experiment is presently active aboard in the International Space Station (ISS) and characterizing such effects in-orbit for numerous state-of-the-art space solar cells with initial results presented herein. © 2013 IEEE.

DOI： 10.1109/PVSC.2013.6745118

Scopus

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Engineering education through on-the-job training in nano-satellite for capacity building in basic space technology development 査読有り

Cho M., Polansky J., Balogh W.

Proceedings of the International Astronautical Congress, IAC 5 3824 - 3828 2013年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Developing countries that in the past have mostly focused on applications-oriented aspects of space technology are increasingly also interested in building indigenous capacities for basic space technology development. A nano-satellite development program is an ideal first-step to establish such a basic capacity. Experience gained through on-the-job training, going through the complete cycle of designing, building and testing a satellite, is crucial to gain this capacity. To fill that demand there is a need for educational institutions to offer appropriate on-the-job training opportunities. In 2010, Kyushu Institute of Technology (Kyutech) and the United Nations Office for Outer Space Affairs launched a long-term fellowship programme on nano-satellite technologies for post-graduate level students from developing countries and countries with economies in transition. The programme has been quite successful. Every year since 2011, two students have enrolled in a Ph.D. course at Kyutech. Based on this success, the fellowship program has been expanded beginning with the class of 2013. The number of fellowship recipients has been increased from two to six. Students seeking a Master degree may also apply. To accommodate the large number of international students, Kyutech will launch a new postgraduate curriculum, the Space Engineering International Course, where students will gain extensive knowledge necessary to build basic space technology in their home countries through various lectures on space engineering in English, laboratory workshops on satellite testing, and participation in various space projects. This paper describes new development details of the fellowship program. ©2013 by the International Astronautical Federation. All rights reserved.

Scopus

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Anomaly investigation of HORYU-II and lessons learned 査読有り

Okumura Y., Masui H., Cho M.

Proceedings of the International Astronautical Congress, IAC 6 4211 - 4218 2013年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The HORYU-II nanosatellite was launched as a secondary payload on-board an H-IIA rocket on May 18, 2012 (UTC). The spacecraft was completely developed by students from Kyushu Institute of Technology starting from 2010. HORYU-II operated normally from orbit injection until June 5 when anomalies were observed in the housekeeping data. By June 30, 2012, only call signs were received. Fortunately, the satellite was able to reset and operate in steady mode, even though the battery state dropped to about 10%. This paper presents HORYU-II anomaly investigation results and the lessons learned. We carried out Fault Tree Analysis (FTA) to determine failure root cause. Among the phenomena observed were: irregular housekeeping data, unresponsive Telecommands from the ground station, communication limited to call signs, and low residual battery quantity after recovery. After ground-based assessment of the spare bus system, we concluded that the anomaly cause was radiation effect on the On-Board Computer (OBC) system. Single Event Latch-up (SEL) occurrence caused over current of the Micro Controller Unit (MCU). We underestimated the radiation effect. We contrived overcurrent protection for the OBC circuit but we did not measure over current flow on the subsystem when SEL occurs. The communication system is independent of the MCU and can continuously send call signs. For this reason, we were able to receive call signs and trace the satellite even when the OBC MCU stopped operating. The power system was designed to restart when battery charge reached 0% and this was confirmed from ground testing. Copyright© (2013) by the International Astronautical Federation.

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Total electron emission yield of solar cell coverglass and optical solar reflector 査読有り

Chen Y., Wu J., Kunimitsu R., Gray A., Toyoda K., Cho M.

IEEE Transactions on Plasma Science 41 ( 12 ) 3558 - 3564 2013年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

Electron-induced secondary electron (SE) emission from space insulating materials is a very important factor in understanding spacecraft charging behavior. Because of the injection of primary electrons (PEs) and the emission of SEs in the surface layer of insulating materials, the target surface can be either negatively or positively charged. In the conventional measurement methods, a single short, low-density pulsed e-beam, charge neutralization using low energy flood e-gun and UV light, and charge dissipation by heating is used. In this paper, a pulsed scanning method for the total electron emission yield measurement of insulating, semiconducting or conducting solid materials is proposed. A total electron detector with large hollow space and insulating spacer was designed, and a pulsed yield scanning measurement system was developed. This method can avoid influence from the charged surface of the insulating material. Using the system, the total SE emission yields of 200 nm thick Au coating on glass, and 11 kinds of solar cell coverglasses and optical solar reflectors produced by Qioptiq have been reported, as induced by a 30 μ s pulse of PEs with ~ 20 nA incident beam current and energies up to 2500 eV. © 1973-2012 IEEE.

DOI： 10.1109/TPS.2013.2288575

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Measurement of atomic-oxygen flux distribution 査読有り

Hisashiba T., Kuroda K., Masui H., Iwata M., Toyoda K., Cho M.

Astrophysics and Space Science Proceedings 32 597 - 606 2013年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

© Springer-Verlag Berlin Heidelberg 2013. Since material surfaces on the outside of spacecraft are exposed directly to the space environment, material having high tolerance to atomic oxygen, ultraviolet rays and radiation are preferred for long time spacecraft operation. In order to examine the influence of atomic oxygen (AO) on space grade materials, an atomic oxygen simulation chamber was developed. A system was developed that generates AO using a laser detonation method. A CO 2 gas laser (5 J) irradiates the oxygen gas in a vacuum chamber (2 MPa) to dissociate the molecular oxygen into atomic. The velocity of AO can be controlled based on the timing between the laser and the gas pulse valve that injects oxygen gas into the chamber. The AO velocity generated by this system is measured using a QMASS (Quadruple Mass Spectrometer) and found to be 8 km/s. It was necessary to measure the AO flux distribution in the chamber at the location where the material samples are exposed to AO. The AO flux distribution was evaluated by measuring the mass gain on a QCM (QuartzCrystal Micro-balance) coated with a silver film upon exposure to the AO.

DOI： 10.1007/978-3-642-30229-9_56

Scopus

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Discharge Observation on Antenna Surface Radiating High Power Microwave in Simulated Space Environment　掲載年月不明　(共著）査読有り

Hyounggwan Woo, Arifur R.Khan, Hirokazu Masui, Mengu Cho, Takehiro Miyakawa, Tatsuhito Fujita

Aerospace Technology Japan (JSASS:The Japan Society for Aeronautical and Space Sciences) 12 11 - 19 2013年01月

Time and Space Redundancy Fault Tolerance Trade-offs for FPGA Based Single and Multicore Designs 掲載年月不明　( 共著）査読有り

Mohamed Mahmoud Ibrahim, Kenichi Asami, Mengu Cho

Japan Society for Aeronautical and Space Science, Transactions-special issue on ISTS 2013年01月

LEO Single Event Upset Emulator for Validation of FPGA Based Avionics Systems掲載年月不明　（共著）査読有り

Mohamed Mahmoud Ibrahim, Kenichi Asami, Mengu Cho

JSASS Transactions-special issue on ISTS-29th 2013年01月

Laboratory Test of Vibration of Micro/Nano Satellite for Environment Test Standardization 　掲載年月不明　( 共著）査読有り

Amgalanbat Batsuren, Toru Hatamura, Hirokazu Masui, Mengu Cho

Special Issue of ISTS, Transactions of Japan Society for Aeronautical and Space Science, Aerospace Technology 2013年01月

Laboratory Tests to Standardize Environment Test Conditions of Micro/Nano Satellite Units　掲載年月不明　（共著）査読有り

Amgalanbat Batsuren, Kenta Tomida, Toru Hatamura, Hirokazu Masui, Mengu Cho

Transactions of Japan Society for Aeronautical and Space Science, Aerospace Technology 2013年01月

Ground tests and on-orbit results of the power system of nano-satellite Horyu-II2　掲載年月不明　（共著）査読有り

Kazuya OKADA, Yuki SERI, Ryunosuke Shibagaki, Kyutech Satellite Project, Hirokazu MASUI and Mengu CHO

Aerospace Technology Aerospace Technology Japan 2013年01月

超小型衛星「鳳龍弐号」の試験・検証と軌道上不具合原因究明　掲載年月不明（共著）査読有り

趙孟佑、増井博一、九州工業大学衛星開発プロジェクト

航空宇宙技術 12 17 - 24 2013年01月

Design of a Multi-Processor System-on-Chip On Board Computer Using FPGA Based Soft IP Cores　掲載月日不明（共著）査読有り

Mohamed Mahmoud Ibrahim Kenichi Asami, Mengu Cho

IOSR-JCE journal 2013年01月

The use of reconfigurable FPGAs in developing reliable satellites on board computers 査読有り

Ibrahim M., Asami K., Cho M.

AIAA SPACE Conference and Exposition 2012 2012年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The design of fault tolerant systems for space applications mandates the use of new techniques to construct robust and reliable systems. Nowadays modern Field Programmable Gate Arrays (FPGA) provide very high logic capacity and low power consumption profiles. The size, weight and thermal characteristics are acceptable even for the non-space grade category. A major trend is to use the commercial grade FPGAs to build satellite systems using fault tolerant design techniques. The commercial grade components are often state-of-art and provide faster and better performance than the well tested and approved space components. In low cost satellite missions, it is acceptable to bear some risk in return for using the widely accessible and low cost commercial grade components. In this paper we present the ongoing development of a robust embedded computer system to be used as the main on-board computer of Micro and Nano satellites at Kyushu Institute of Technology, Japan. The system makes use of the soft IP cores available for the Microblaze processors from Xilinx Inc. The Xilinx FPGAs are Static Random Access Memory (SRAM) based and do not apply the anti-fused technology. They need periodic scrubbing for the SRAM memory holding the hardware design. Xilinx introduced a reconfigurable technique to facilitate the reconfiguration of their FPGAs even while operating without affecting other parts of the design. This technique is known as partial reconfiguration, in which parts of the system will be reconfigured while the rest of the system is functioning without interruption. It provides a facility to improve the development of fault tolerant FPGA designs through read-back and then reconfiguration of faulty FPGA modules. We present our use of this technique to build a robust On-Board computer system on SRAM based FPGAs using soft Intellectual Property (IP) cores. The results of applying this technique are discussed in terms of gains, drawbacks and the effects on the overall fault tolerance performance. © 2012 by Mohamed Mahmoud Mohamed Ibrahim. Published by the American Institute of Aeronautics and Astronautics, Inc.

Scopus

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Preliminary report on on-orbit experiment on high voltage technology demonstration satellite, HORYU-II 査読有り

Takahashi A., Khan A., Masui H., Iwata M., Toyoda K., Cho M.

Proceedings of the International Astronautical Congress, IAC 12 9657 - 9667 2012年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

A cubic nano-satellite with a length of 30 cm, named HORYU-II, was developed at Kyushu Institute of Technology in Japan. HORYU-II is a demonstration satellite for high voltage technology and its two main advantages are its low cost and short time development. HORYU-II's main mission is to demonstrate the possible generation of 300V on-orbit by using spherical solar cells connected in series. This mission can be considered as the first high voltage technology demonstration in the world. To control arcing under negative 300V in space plasma, ETFE (ethylene tetra flouro ethylene) cover and semi-conductive coated solar array efficiency will be demonstrated. Along with this, charging mitigation of spacecraft by using electron emitting film, operation of commercial-off-the-shelf (COT) surface potentiometer will also be demonstrated. HORYU-II was launched by a H-IIA rocket on May 18, 2012. We have been acquiring on-orbit data and monitoring the satellite conditions. HORYU-II succeeded in generating the highest 300V photovoltaic voltage in space for the first time in the world. However, many problems were found during data collection. In this paper, the result of HORYU-II's missions is described.

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Horyu-2 educational satellite: Lessons learnt and future perspectives 査読有り

Ibrahim M., Faure P., Asami K., Cho M.

AIAA SPACE Conference and Exposition 2012 2012年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Educational satellites are being built with many Universities and research institutes all over the world. The purpose of such satellite projects is to train and educate under graduate, graduate and post graduate students on the concepts and practices of satellite engineering. A major issue that should be studied after the project finishes is the evaluation of the project in terms of the lessons learnt. This evaluation provides the research institute or the University with the necessary feedback and guidance for future missions and research. In this paper we present an evaluation for the Horyu-2 project, a Nano-Satellite built in Kyushu Institute of Technology (Kyutech) in Japan. The evaluation is a kind of a strategic audit to judge the appropriateness and fitness of the applied strategies in educational satellite development activities at Kyutech. The study provides recommendations to maximize the benefits in future projects. It is based on interviewing all the project members and performing field surveys to carefully point out the Strengths and Weaknesses in the internal environment of the satellite development center. The external Opportunities and Threats were identified by studying several factors in the economic, social, political, legal and technological dimensions. The Strengths, Weaknesses, Opportunities and Threats were used to develop a SWOT analysis to propose and recommend future strategies. The Horyu-2 satellite experiment was studied as a model that can possibly be exported to other countries especially developing countries and countries just starting their space activities. © 2012 by Mohamed Mahmoud Mohamed Ibrahim. Published by the American Institute of Aeronautics and Astronautics, Inc.

Scopus

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Fault tolerant architecture alternatives for developing nano-satellites embedded computers 査読有り

Ibrahim M., Asami K., Cho M.

AIAA SPACE Conference and Exposition 2012 2012年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Nano-Satellites development is spreading tremendously nowadays. The fact that Nano-Satellites are of low development cost thus the risk incurred is affordable makes them the premiere choice as technology demonstrators and test beds. This satellite category is characterized with the use of Commercial-Of-The-Shelf (COTS) components, neither space approved nor radiation hardened components are usually used in its development. This paper introduces a challenge in building reliable yet low cost systems, constructed from commercially available components. Nano-Satellites should keep on using such grade of components as this gives them the unique feature of being accessible to wide category of space practitioners and universities within the limited budgets. A crucial part in any satellite system is its embedded computer system known as the On-Board computer which might carry tasks, according to the mission design, ranging from command and data handling to full control over the payload and scientific data collection. The satellite architecture either it is distributed consisting of more than one processing node or concentric consisting of one powerful computing node, still needs to apply fault tolerance design techniques to provide robustness for the system. In this paper we present a group of architecture alternatives that are considered, during our effort to develop a fault tolerant On-Board computer at Kyushu Institute of Technology, Japan. © 2012 by Mohamed Mahmoud Mohamed Ibrahim. Published by the American Institute of Aeronautics and Astronautics, Inc.

Scopus

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Discharge observation on antenna surface radiating high power microwave in plasma environment 査読有り

Woo H., Khan A., Masui H., Cho M., Miyakawa T., Fujita T.

Proceedings of the International Astronautical Congress, IAC 9 7029 - 7037 2012年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Space Solar Power System (SSPS) transfers enormous amount of electrical energy through microwave. Flight demonstration onboard a small satellite in Low Earth Orbit (LEO) is now under consideration. When a high power microwave is irradiated from antenna in LEO plasma environment, there is a concern about discharge caused by interaction between the plasma and the microwave. There has been no experimental observation on such interaction phenomenon. Verification experiment is essential for SSPS to become a reality. We have set-up an experimental system that can simulate the radiation of high power microwave under dense plasma in a vacuum chamber. A RF plasma source was installed to the chamber that we filled with Argon plasma environment of density from 1011 to 10 m' with 4eV to 6eV temperature under a back pressure of 2.6x10" Pa. A patch antenna made of Glass epoxy substrate was installed inside the chamber. The antenna was connected to a magnetron that could produce 5.8GHz microwave. We monitored the antenna surface temperature, the radiated and reflected power, the chamber pressure and others while we injected the microwave to the antenna up to 45W. We examined whether discharge or related phenomena occur or not on the patch antennas for various conditions to verify the hypothesis of discharge inception that discharge is caused by multi-pactoring and breakdown of the outgas product. Copyright © (2012) by the International Astronautical Federation.

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Special issue on spacecraft charging technologies

Cho M., Cooke D., Ferguson D., Garrett H., Hilgers A., Lai S., Roussel J., Toyoda K., Wheelock A.

IEEE Transactions on Plasma Science ( IEEE Transactions on Plasma Science ) 40 ( 9 ) 2012年09月

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