研究者詳細 - 趙　孟佑

論文 - 趙　孟佑

分割表示643 件中 121 - 140 件目／全件表示 >>

Ionosphere measurement: Point-to-point total electron content estimation using UHF inter-satellite ranging for CubeSat constellation 査読有り国際誌

Elmegharbel H.A., Kishimoto M., Orger N.C., R-Schulz V., Dayarathna T., Rahmatillah R., Teramoto M., Cho M., Chow C.L., Tse M.S., Li H.

Proceedings of the International Astronautical Congress, IAC 2020-October 2020年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The ionosphere, which is the upper ionized layer of the atmosphere, affects the transmission of radio waves and causes degradation in the performance of satellite-based navigation, communication, and surveillance systems. Measurements by satellites are used to validate the numerical models of the ionosphere by estimating the total electron content (TEC) along the propagation path of the radio waves from satellite to ground. TEC is simply the total number of electrons along a ray path from a transmitter to the receiver. The delay experienced by a signal travelling in the ionosphere is proportional to the TEC along the signal path. Consequently, mapping the state of the ionosphere in real-time is an important scientific study for the dynamic nature of the ionosphere which would as well help in maintaining the accuracy of these radio-based systems. Various techniques to mitigate these ionospheric effects were developed in the past decades; a widely distributed network of global navigation satellite system (GNSS) receivers provides 3D distributions of the electron density in the ionosphere on the regional scales and its temporal fluctuations. A constellation of CubeSats can be used to estimate TEC along the UHF links between these satellites and a network of ground stations; the time delay of the propagating signals is used to derive a single value of TEC and hence multiple measurements of vertical and slant TEC can be used to derive a global map of the ionosphere. The advantage of using the UHF band is its higher vulnerability to ionospheric effects. This paper will propose the design requirements and hardware implementation and testing of a payload for a CubeSat used for signal timestamped reception using the UHF communication band in addition to on-board processing to derive TEC values between satellite and ground station. The development of this payload is part of Space Precision Atomic-clock TIming Utility Mission (SPATIUM) project which was proposed by Laboratory of Lean Satellite Enterprises and In-Orbit Experiments (LaSEINE) of Kyushu Institute of Technology, Japan in collaboration with Nanyang Technological University, Singapore to measure the electron density distribution using a constellation of intercommunicating Cube-Satellites equipped with a highly precise atomic clock in different LEO orbits and a network of ground stations. SPATIUM-I is currently in orbit down-linking signals to be processed in the ground station, SPATIUM-II is currently under development to demonstrate the on-board processing of Up-link signals to the satellite.

Scopus

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Horyu-VI: International cubesat mission to investigate lunar horizon glow 査読有り国際誌

Orger N.C., Cho M., Iskender O.B., Lim W.S., Chandran A., Ling K.V., Holden K.H.L., Chow C.L., Bellardo J., Faure P., Santoni F., Circi C., Marzioli P., de Grossi F., Frezza L., Toyoda K., Masui H., Mariko T., Alarcon J.R.C., Yamauchi T., Kim S., Lim J.W.M., Potrivitu G., Laterza M.

Proceedings of the International Astronautical Congress, IAC 2020-October 2020年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Interaction with the solar wind and UV/X-ray irradiation can cause the lunar dust to be electrostatically charged and mobilized all around the Moon, and light scattering by this dust cloud can be observed over the lunar terminator. This phenomenon, which has also been called the lunar horizon glow (LHG), still remains unexplained. The LHG observations using conventional lunar probes have limited observation opportunities and do not cover varying space weather conditions in cislunar environment such as strong upstream plasma flow and micrometeoroid flux that could enhance the lunar dust presence in the exosphere. The nanosatellite “HORYU-6” specialized in LHG observations will be put into lunar orbit to detect the light scattering above the lunar terminator. The proposed payload will perform multi-spectral imaging to monitor the lunar horizon several minutes before orbital sunrise or after orbital sunset for light scattering analysis. We show that we can obtain scientific results of lunar and planetary exploration using CubeSat at low cost and in a short period of time, and contribute to the development of lunar and planetary exploration in the future. The spacecraft will be developed jointly with universities in Singapore, the United States and Italy under the supervision of Kyushu Institute of Technology, with the aim of launching the SLS-2 rocket in the second half of 2022. Together with its own scientific objectives, the HORYU-6 mission will demonstrate the low thrust trajectory optimization by utilizing electric propulsion system together with other novel embedded technology demonstrations such as atomic clock, deep space navigation and communication with CubeSats.

Scopus

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Difference in threshold voltage of arc inception between electron beam and ultraviolet environment 査読有り国際誌

Toyoda K., Kose S., Sasaki T., Cho M.

AIAA Scitech 2020 Forum 1 PartF 2020年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

As a charging method in ground experiments, an electron beam is often used to simulate high energy particles. In addition to this, a charging method using ultraviolet has been devised because charging by sunlight also occur in the space environment. Accordingly, ultraviolet were used for the discharge threshold measurement experiment of the solar cell, but the large difference of the threshold voltage was seen in two charging methods. The purpose of this research is to find out the cause of this large difference and to apply ultraviolet to charging and discharge experiment of space solar cell. We assumed that the charging potential of the cover glass edge of the solar cell was different in two charging methods and it caused the difference of the discharge threshold voltage. Therefore, we measured the surface potential focusing on the cover glass edge. In the experiment, a sample simulating the structure of the space solar cell was prepared and irradiated with ultraviolet or electron beam until the potential of the cover glass surface did not change overall. The surface potential of the cover glass edge at this time was measured with a contactless surface electrometer, and the results by two charging methods were compared. As a result, it was found that the surface potential at the cover glass edge was different in two charging methods. On the other hand, it was also found that measurement accuracy was low. We devised measurement method using Pockels effect which can measure potential directly or plan to improve measurement accuracy by improving sample because higher measurement accuracy is required to clarify the difference in charging.

DOI： 10.2514/6.2020-2012

Scopus

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Peltier-based Thermal Testing (PeTT) Vacuum Chamber: Affordable Testing Facility for Lean Satellites 査読有り国際誌

Bonsu Benjamin, Hirokazu Masui, Mengu Cho

UNISEC Space Takumi Journal 8 ( 2 ) 11 - 38 2019年12月

Near-zero metamaterial inspired UHF antenna for nanosatellite communication system 査読有り国際誌

Alam T., Islam M., Cho M.

Scientific Reports 9 ( 1 ) 2019年12月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019, The Author(s). Epsilon-and-mu-near-zero (EMNZ) metamaterial structure inspired UHF antenna for nanosatellite has been proposed in this paper. The antenna consists of 3 × 2-unit cell array on the ground plane and a meander line radiating patch. Coaxial probe feeding technique has been obtained to excite the antenna. The meander line enables the antenna to resonate at lower UHF band and the metamaterial array is used to make the resonant frequency stable by reducing the coupling effect with metallic nanosatellite structure. The metamaterial structure exhibits EMNZ characteristics from 385 MHz to 488.5 MHz, which facilitates stable resonant frequency and higher antenna efficiency when embedded with nanosatellite structure. The proposed EMNZ inspired antenna has achieved measured impedance bandwidth (S 11 < −10 dB) of 14.92 MHz (391 MHz–405.92 MHz). The perceptible novelty of this paper is the development of EMNZ metamaterial that significantly improves the UHF antenna’s operating frequency stability as well as efficiency for low earth orbit nanosatellite communications.

DOI： 10.1038/s41598-019-40207-3

Scopus

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Techniques for Repeatable Pyroshock Testing on an Air Gun Shock Machine for Lean Satellites 査読有り国際誌

18. Ibukun Oluwatobi ADEBOLU, Hirokazu MASUI, Isamu INOUE , Mengu CHO

90th Shock and Vibration Symposium 2019年11月

Store and Forward Data Collection Using Low-Cost Sensor Stations 査読有り国際誌

Pooja Lepcha, Mengu Cho

4th International BIRDS Workshop 2019年11月

Propose Strategy to Increase Capacity Development for Cubesat Thermal Vacuum Testing in Africa 査読有り国際誌

Bonsu Benjamin, Hirokazu Masui, Mengu Cho

8th International Conference on Space Science and Satellite Technologies Application 2019年11月

BIRDS-3 Satellite Project Including the First Satellites of Sri Lanka and Nepal 査読有り国際誌

Withanage Dulani Chamika, Mengu Cho, George Maeda , Sangkyun Kim , Hirokazu Masui , Takashi Yamauchi , Sanath Panawannege

70th International Astronautical Congress 2019年10月

Introducing Low-Cost Thermal vacuum Testing Facility for the emerging space program in African Universities in Africa 査読有り国際誌

Bonsu Benjamin, Hirokazu Masui, Mengu Cho

70th International Astronautical Congress 2019年10月

Status of Assembly, Integration, and Testing (AIT) Facilities for Satellite Testing in Africa 査読有り国際誌

Bonsu Benjamin, Hirokazu Masui, Mengu Cho

27th Workshop on Space Technology for Socio-Economic Benefit, UN/IAF Symposium 2019年10月

Feasibility Analysis of Optical Communication System for a Moon Orbiting CubeSat and Earth Station 査読有り

Femi Ishola, Mengu Cho

70th International Astronautical Congress 2019年10月

How Seven Emerging Nations Entered the Space Age via BIRDS Projects 1 through 4 査読有り国際誌

George Maeda, Mengu Cho, Hirokazu Masui, Sangkyun Kim, Takashi Yamauchi

70th International Astronautical Congress IAC-19 2019年10月

New star identification algorithm using labelling technique 査読有り国際誌

Kim S., Cho M.

Acta Astronautica 162 367 - 372 2019年09月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 IAA A new star identification algorithm is proposed for the attitude determination of a star sensor in the lost-in-space case, where prior attitude information is not available. The algorithm is based on a labelling technique, which uses label values to represent each group of stars. Using label values, multiple stars are simultaneously identified without repetition of search work. This labelling algorithm allows for a fast identification speed with efficiency, and provides the capability of more reliable identification by redundant confirmation. The proposed algorithm was verified by simulation study under various conditions.

DOI： 10.1016/j.actaastro.2019.06.007

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A Performance Comparison of Solid Propellants in Surface Arc Thruster: Sulfur and Teflon 査読有り国際誌

Senior Shimhanda, Kotaro Hiraka, Hiroaki Murakami, Kazuhiro Toyoda, and Mengu Cho,

36th International Electric Propulsion Conference 2019年09月

Anomaly Investigation using Telemetry Data of Horyu-2 for Single Event Latch-up 査読有り国際誌

Hirokazu MASUI, Yuzo TANAKA, Takahiro TOMIOKA, Hiroshi FUKUDA,Kyutech satellite project , Mengu CHO

UNISEC Space Takumi J. 8 ( 1 ) 1 - 10 2019年09月

Attitude Testing Platform in a Vacuum Environment for a Lean Satellite with an Electric Thruster 査読有り国際誌

Marcos Hernandez-Herrera, Phongsakorn Meemak, Hiroki Hisatsugu, Kotaro Hiraka, Jose Rodrigo Cordova-Alarcon, Sangkyun Kim, Kazuhiro Toyoda, Mengu Cho

Journal of Small Satellites (JoSS) 08 ( 02 ) 849 - 858 2019年09月

AOBA VELOX-IV: 2U CubeSat for the technological demonstration of lunar horizon glow mission 査読有り国際誌

Kim S., Orger N., Cordova-Alarcon J., Hernandez-Herrera M., Masui H., Yamauchi T., Toyoda K., Cho M., Duy Vu B., Vinh T., Seng L., Hiang C.

Acta Astronautica 161 328 - 337 2019年08月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 IAA AOBA VELOX-IV is a 2U-sized CubeSat that has been developed by the Kyushu Institute of Technology and Nanyang Technological University for the technological demonstration of a future lunar mission. Decades ago, Surveyor and Apollo programs reported light scattering observations on the horizon of the Moon; however, only a limited number of investigations were performed after the Apollo program to observe the lunar horizon glow (LHG). It is still unknown what conditions produce the light glow on the horizon of the Moon. The lunar mission of the AOBA VELOX project is planning to send CubeSats to the Moon and to capture images of the LHG on the lunar orbit while determining the conditions that can support light scattering above the lunar horizon. Before the satellites go into the lunar orbit, the necessary technologies must first be confirmed in Earth orbit. AOBA VELOX-IV was launched to low earth orbit via a JAXA Epsilon rocket in 18th January 2019. This paper explains the LHG mission first, and presents an overview of AOBA VELOX-IV, its payloads, technical issues, and the flight model.

DOI： 10.1016/j.actaastro.2019.05.046

Scopus

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Guest Editorial Spacecraft Charging Technology 査読有り国際誌

Andersen A., Bodeau M., Cho M., Davis V., Dennison J., Donegan M., Ferguson D., Green N., Inguimbert V., Jun I., Lai S., Likar J., Minow J., Parker L., Roussel J., Toyoda K., Garrett H., Usui H.

IEEE Transactions on Plasma Science 47 ( 8 ) 3629 - 3630 2019年08月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 1973-2012 IEEE. This marks the seventh issue of the IEEE Transactions on Plasma Science dedicated to Spacecraft Charging Technology. The theme of this issue is based on the papers presented at the 15th Spacecraft Charging Technology Conference, Kobe, Japan, in 2018. The history of spacecraft charging goes back to the first Spacecraft Charging Technology Conference, sponsored by AFRL and NASA, that was held at the U.S. Air Force Academy, Colorado Springs, CO, USA, in 1978. The 15th Spacecraft Charging Technology Conference was hosted by the Japan Aerospace Exploration Agency (JAXA) and the Graduate School of System Informatics, Kobe University. It continues a tradition of international conferences on a ~2-year cycle. This conference, as well as each previous one in the series, was a great success. The topical discussions have greatly helped in making progress in the fields of spacecraft charging, spacecraft-plasma interactions, and related areas. At the end of the 15th Conference, the assembly agreed to request publication of the proceedings of the conference in the IEEE Transactions on Plasma Science and to encourage the submission of the papers presented at the conference to the Journal.

DOI： 10.1109/TPS.2019.2925231

Scopus

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Analysis of Charging of the HTV-4 Based on On-Orbit Data 査読有り国際誌

Tsujita D., Okumura T., Kobayashi Y., Kasai T., Ohkawa Y., Koga K., Cho M.

IEEE Transactions on Plasma Science 47 ( 8 ) 3905 - 3914 2019年08月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 1973-2012 IEEE. After three H-II transfer vehicles (HTVs) had finished their mission to resupply the International Space Station (ISS), NASA requested data of the HTV's potential to evaluate the charging/discharging process that occurs when the HTV docks to the ISS. To measure these data, a new instrument was installed on the fourth HTV. This instrument allows us to measure the HTV-4 surface potential relative to the surrounding plasma, and is called advanced technology on-orbit test instrument for space environment-mini (ATOTIE-mini). The ATOTIE-mini observed the HTV's local potential in the orbit for more than one month. The measured potential during the HTV solo-flight phase varied between-30 and-60 V in sunlight and was about 0 V in eclipse conditions. The HTV's potential during the time when it was docked to the ISS followed the ISS's potential with an almost constant offset of about 10 V. The data measured by ATOTIE-mini are consistent with those measured by the floating potential measurement unit on the ISS, and thus are considered reliable. The HTV's potential level itself was acceptable for ISS. Note that the solar array panels can generate up to approximately 120 V, which is much larger than the absolute potential range in sunshine. We analyze the potential distribution on the HTV surface by a multi-utility spacecraft charging analysis tool, because ATOTIE-mini can only observe one point on the HTV surface. The analysis results are discussed with respect to the flight attitude.

DOI： 10.1109/TPS.2019.2920153

Scopus

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