• The Science & Technology
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• no.5 s.468
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• pp.55-57
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• 2008

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.3-7
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• 2008

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.654-657
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• 2011

For the successful development of korean exploraton program, KARI started development of ground test model for lunar lander from last year. In order to secure core technology for space propulsion system, Koreanization of propellant tank is proceeding and it will be used for final assembly and test for ground test model. In this paper, the development result of titanum tank shell and verification test result was presented.

• Journal of the Korea Society for Simulation
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• v.28 no.1
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• pp.93-98
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• 2019

In case of unmanned aerial vehicles used in modern society, there has been a problem where a human operator should be still needed to control the UAV because of a lower level of autonomy. In this paper, genetic algorithm is selected as a methodology for the autonomy accomplishment and then we verify a possibility of UAV autonomy by applying the GA. The landing is one of the important classical tasks on aerial vehicle and the lunar Landing is one of the most historical events. Autonomy possibility of computer-simulated UAV is verified by landing autonomy method of a falling body equipped with a propulsion system similar to the lunar Lander. When applying the GA, the genom is encoded only with 4 actions (left-turn, right-turn, thrust, and free-fall) and applied onto the falling body, Then we applied the major operations of GA and achieved a success experiment. A major contribution is to construct a simulated UAV where an autonomy of UAV can be accomplished while minimizing the sensor dependency. Also we implemented a test-bed where the possibility of autonomy accomplishment by applying the GA can be verified.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.4
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• pp.37-43
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• 2011

Lunar exploration program has been prepared with the aim of launch in the 2020's. As part of it, a lunar lander demonstrator has been developed which is the model for verifying all the system, such as structure, propulsion and control system before launch to deep space. After verifying all the system, the demonstrator will be evaluated by flight test. This paper deals with path tracking controller based on thrusters for the demonstrator. For this, first we derive equations of motion according to the allocation of thrusters and design the path tracking controller. The signal generated from the controller is continuous so PWPF(Pulse-Width Pulse-Frequency) modulator is adopted for generating on/off signal. Finally MATLAB simulation is performed for evaluating the path tracking ability and the final landing velocity.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.22 no.4
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• pp.75-80
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• 2014

A lunar lander demonstrator developed for the purpose of demonstrating lunar landing technologies recently in Korea. The thruster control system of the lunar lander demonstrator adopted the main thrusters for altitude control and the reaction thrusters for attitude control. In this paper, we propose a path tracking controller base on Euler angles. The control signals of the controller are of continuous type. And Pulse Width Modulator(PWM) is adopted to provide On/Off signals. We perform MATLAB simulation for evaluating the path tracking performance and the final landing velocity of the lunar lander demonstrator.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.40.1-40.1
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• 2009

미래 한국의 달궤도선 임무에 대비하여 달 근접 궤도 전파기인(orbit propagator) YSPLOP ver. 1(Yonsei Lunar Precise Orbit Propagator version 1)을 개발 하였다. 개발된 궤도 전파기의 성능은 상용 소프트웨어인 STK Astrogator를 이용하여 검증되었다. 개발된 궤도 전파기를 이용, 달 궤도선의 운용에 있어서 다양한 섭동력들이 궤도선의 수명(orbital decay)에 미치는 영향을 분석하였다. YSPLOP ver. 1은 정밀한 달 중심 탐사선의 위치산출을 위하여 M-EME2000 (Moon-Centered, Earth Mean Equator and Equinox of J2000) 좌표계, M-MME2000 (Moon-Centered, Moon Mean Equator and IAU vector of epoch J2000) 좌표계 그리고 M-MEPMD (Moon-Centered, Moon Mean Equator and Prime Meridian) 좌표계를 이용하여 탐사선의 상태(state) 정보를 산출한다. 또한 태양, 지구, 달, 화성, 목성의 중력에 의한 섭동력 및 태양풍에 의한 영향을 포함할 수 있도록 설계되었으며, 달 근접 궤도선의 궤도 운동에 가장 큰 영향을 미칠 수 있는 섭동력인 달의 비대칭 중력장에 의한 영향 또한 고려하도록 하였다. 달의 비대칭 중력장 모델 (Lunipotential model)은 LP165p 모델이 사용되었으며 행성의 정밀한 위치 산출을 위하여 JPL의 DE405 천체력이 사용되었다. 개발된 궤도 전파기를 이용, 달고도 100 km, 궤도 경사각 $90^{\circ}$인 달 중심의 극궤도를 약 30일 동안 전파한 결과, YSPLOP ver. 1의 성능은 STK Astrogator와 비교하여 보았을 때 약 수 m의 오차를 보이는 것으로 확인되었다. 달의 극궤도 탐사선의 궤도 수명을 분석한 결과, 최소한 달의 비대칭 중력장이 70 by 70 이상으로 고려되어야 함을 확인하였으며 이때 달 궤도선의 수명은 약 160일으로 나타났다. 아울러 달 근접 환경에서의 지구 중력에 의한 섭동력은 달 궤도선의 운동에 있어서 무시 할 수 없는 정도의 많은 영향을 끼치고 있음을 확인하였다. 이 연구를 통하여 개발된 궤도 전파기는 미래 한국의 달 궤도선 및 착륙선의 임무 설계시 사용 될 수 있다. 또한 이 연구에서 제시된 달 근접 환경에서의 다양한 섭동력들이 달 궤도선의 운동에 미치는 영향에 대한 해석 결과는 추후 달 근접 임무 설계시 고려되어야 하는 섭동력들의 기본 사양을 제공할 것이다.

• The Journal of the Petrological Society of Korea
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• v.19 no.4
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• pp.245-254
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• 2010

Technology of surface investigation using X-ray is one of widely used technology nowadays. This technique has been numerously used for planetary surface investigations for both orbital and rover scientific instruments. Korea has a plan to send an orbiter and lander to the Moon by the early 2020s. Therefore, the time has come for Korean researchers to develop major scientific instruments and start to do research on basic research for the Moon. Because of this situation, we firstly investigate X-ray technology, which is essential as one of core techniques of planetary remote sensing from the orbit and ground. This paper presents the current status of planetary exploration using X-ray techniques and new development of worldwide X-ray technology which could be adapted for prospective planetary missions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.12
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• pp.1028-1036
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• 2018

KARI plans to launch Korea Pathfinder Lunar Orbiter (KPLO) to the Moon by December 2020 for the first step of the Korea Lunar Exploration Project. This orbiter will be launched to obtain lunar exploration technologies and science data in advance before launching a main orbiter and a lunar probe. This paper describes the verification of thermal design for the orbiter. It is exposed to more extreme thermal environment than that of low Earth orbit satellite due to the heavy infrared emission of the Moon. Accordingly, a thermal design considering this environment is needed to maintain the temperature of payloads and components equipped in the orbiter within operating temperature range in all orbits. We performed the thermal analysis for Earth-Moon transfer orbit, lunar mission orbit and lunar eclipse required for thermal design verification of the lunar orbiter. As a result, this thermal design met the design requirements.

• Aerospace Engineering and Technology
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• v.13 no.1
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• pp.96-107
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• 2014

Korea Aerospace Research Institute has a plan to launch experimental lunar orbiter in 2017, and lunar orbiter and lander in 2020. In the mission planning phase, LOI(Lunar Orbit Insertion) maneuver strategy should be designed using finite burn model because on-board propulsion system of lunar orbiter in finite burn type. LOI maneuver plan and amount of required ${\Delta}V$ using finite burn model depend on the spacecraft attitude at burn, a type of propellant, thrust level and burn timing. This paper describes the LOI maneuver of lunar orbiter of foreign space agency and then comes up with the LOI maneuver plan of Korean lunar orbiter. Adequate thrust level and burn duration of Korean lunar orbiter also present by performing simulation.