• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.6
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• pp.495-504
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• 2014

Solar sail spacecrafts can gain propulsion using the momentum change through reflecting the photon packets of energy from the Sun. The sail slowly but continuously accelerates to accomplish a wide-range of potential missions. To develop the potential mission of the solar sail, the configuration, the film characteristics and the deployment devices should be carefully considered. In this paper, recent development and activities of the solar sail are introduced and design technology of the sail subsystem is investigated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.10
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• pp.765-772
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• 2020

A lot of studies to overcome the limitation of flight time have been studied, since the requirement of complicated mission achievement of aircraft including Unmanned Aerial Vehicles(UAVs) has been increased. The fuel limitation could bring about not enough flight time to accomplish missions. For this reason, the rendezvous maneuver is required to accomplish aerial refueling missions. The rendezvous guidance law based on variable pursuit guidance is designed using Lyapunov stability theory in this study. Numerical simulation is performed to demonstrate the performance of the proposed rendezvous guidance.

• Journal of Astronomy and Space Sciences
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• v.32 no.3
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• pp.247-256
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• 2015

In this work, an efficient method with which to evaluate the high-degree-and-order gravitational harmonics of the non-sphericity of a central body is described and applied to state predictions of a lunar orbiter. Unlike the work of Song et al. (2010), which used a conventional computation method to process gravitational harmonic coefficients, the current work adapted a well-known recursion formula that directly uses fully normalized associated Legendre functions to compute the acceleration due to the non-sphericity of the moon. With the formulated algorithms, the states of a lunar orbiting satellite are predicted and its performance is validated in comparisons with solutions obtained from STK/Astrogator. The predicted differences in the orbital states between STK/Astrogator and the current work all remain at a position of less than 1 m with velocity accuracy levels of less than 1 mm/s, even with different orbital inclinations. The effectiveness of the current algorithm, in terms of both the computation time and the degree of accuracy degradation, is also shown in comparisons with results obtained from earlier work. It is expected that the proposed algorithm can be used as a foundation for the development of an operational flight dynamics subsystem for future lunar exploration missions by Korea. It can also be used to analyze missions which require very close operations to the moon.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.11
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• pp.1042-1051
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• 2011

In this paper, a total operating environment equipped with onboard wireless communication systems and ground-based mission control systems is proposed for simultaneous operation of multiple UAVs. A variety of operating structures are studied and classified systematically based on types and usages of the components. For each operating system, the strength, weakness and reliability aspects are investigated. Based on these results, a proper operating system configuration is determined and components are developed for mission formation flight. Proposed system can make a formation flight of various UAVs, execute complex missions decentralizing mission to several UAVs and cooperate several missions.

• International Journal of Aeronautical and Space Sciences
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• v.6 no.2
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• pp.64-75
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• 2005

The Stratospheric Airship Platform (SAP) has a capability of performing the autonomous and guidance flight to satisfy given missions. To be used as the High Altitude Platforms (HAPs), the capabilities of controlling platform's accurate position and keeping the station point are the most important features. Under this circumstances Autonomous Flight Control System (AFCS) is a critical system and plays a key role in achieving the given requirements and succeeding in missions. In this paper, the design and analysis results of the AFCS algorithms and controller are presented. The brief summary of the AFCS hardware structure is also explained. The autopilot controller and guidance logics were designed based on the linear dynamics of the unmanned airship platform and the full nonlinear dynamics was considered to evaluate and verify their performances.

• Advances in aircraft and spacecraft science
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• v.7 no.3
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• pp.271-290
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• 2020

The paper describes the analysis of deployment strategies and trajectories design suitable for executing the inspection of an operative spacecraft in orbit through re-usable CubeSats. Similar missions have been though indeed, and one mission recently flew from the International Space Station. However, it is important to underline that the inspection of an operative spacecraft in orbit features some peculiar characteristics which have not been demonstrated by any mission flown to date. The most critical aspects of the CubeSat inspection mission stem from safety issues and technology availability in the following areas: trajectory design and motion control of the inspector relative to the target, communications architecture, deployment and retrieval of the inspector, and observation needs. The objectives of the present study are 1) the identification of requirements applicable to the deployment of a nanosatellite from the mother-craft, which is also the subject of the inspection, and 2) the identification of solutions for the trajectories to be flown along the mission phases. The mission for the in-situ observation of Space Rider is proposed as reference case, but the conclusions are applicable to other targets such as the ISS, and they might also be useful for missions targeted at debris inspection.

• Bulletin of the Korean Space Science Society
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• 2005.10a
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• pp.63-63
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• 2005

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.57.2-57.2
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• 2019

The NISS (Near-infrared Imaging Spectrometer for Star formation history) onboard NEXTSat-1 was successfully launched on last December and is now under the operation phase. The capability of both imaging and spectroscopy is a unique function of the NISS. It has realized the imaging spectroscopy (R~20) with a wide field of view of $2{\times}2deg$. in a wide near-infrared range from 0.95 to $2.5{\mu}m$. The major scientific mission is to study the cosmic star formation history in the local and distant universe. It also demonstrated the space technologies related to the infrared spectro-photometry in space. The NISS is performing the imaging spectroscopic survey for local star-forming galaxies, clusters of galaxies, star-forming regions, ecliptic deep fields and so on. As an extension of the NISS, the SPEHREx (Spectro-Photometer for the History of the Universe Epoch of Reionization, and Ices Explorer) was selected as the NASA MIDEX (Medium-class Explorer) mission (PI Institute: Caltech). As an international partner, KASI will participate in the development and the science for SPHEREx. It will perform the first all-sky infrared spectro-photometric survey to probe the origin of our Universe, to explore the origin and evolution of galaxies, and to explore whether planets around other stars could harbor life. Compared to the NISS, the SPHEREx is designed to have a much wider FoV of $3.5{\times}11.3deg$. as well as wider spectral range from 0.75 to $5.0{\mu}m$. Here, we introduce the status of the two space missions.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.47.1-47.1
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• 2018

The NISS (Near-infrared Imaging Spectrometer for Star formation history) onboard NEXTSat-1 have successfully developed by KASI. The capability of both imaging and spectroscopy is a unique function of the NISS. At first, it have realized the low-resolution spectroscopy (R~20) with a wide field of view of $2{\times}2deg$. in a wide near-infrared range from 0.95 to $2.5{\mu}m$. The major scientific mission is to study the cosmic star formation history in local and distant universe. It will also demonstrate the space technologies related to the infrared spectro-photometry in space. Now, the NISS is ready to launch in late 2018. After the launch, the NISS will be operated during 2 years. As an extension of the NISS, the SPEHREx (Spectro-Photometer for the History of the Universe Epoch of Reionization, and Ices Explorer) is the NASA MIDEX (Medium-class Explorer) mission proposed together with KASI (PI Institute: Caltech). It will perform the first all-sky infrared spectro-photometric survey to probe the origin of our Universe, to explore the origin and evolution of galaxies, and to explore whether planets around other stars could harbor life. Compared to the NISS, the SPHEREx is designed to have much more wide FoV of $3.5{\times}11.3deg$. as well as wide spectral range from 0.75 to $5.0{\mu}m$. After passing the first selection process, the SPHEREx is under the Phase-A study. The final selection will be made in the end of 2018. Here, we report the status of the NISS and SPHEREx missions.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.3
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• pp.348-357
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• 2013

This work describes an approach that contributes to derive from mission to critical functions of the attack helicopter under future battle space environment. An existing mission of the attack helicopter is limited to the only shooter oriented functions. In the future environment, mission and its functions of the helicopter might be much expanded. The functions should be derived by the top down approach based on systems engineering approach. In this point of view, this work describes network based future battle environment. From this environment, the missions of the attack helicopter are identified and optimized functions are derived through sequential procedures like from missions to tasks, tasks to activities, and activities to functions. The selected activities are obtained from the tasks using QFD. The weighting scores of the QFD are calculated by the AHP computational procedure. Finally the critical functions are presented through the similar procedure.