• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.162.1-162.1
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• 2012

한국형 달 착륙선의 안전하고 효율적인 달 착륙을 위해 임무 시나리오 시뮬레이션을 수행하였다. 달 착륙은 보통 두 가지 방법이 사용되는데, 지구에서 출발하여 달에 도착한 후 달착륙지에 직접 착륙하는 방법과 달의 주차궤도를 돌다가 달 착륙지에 착륙하는 방법이 있다. 미국의 Surveyor호는 직접 착륙 방법을 사용하였고 아폴로 시리즈는 달 궤도를 공전하다가 착륙하는 방법을 사용하였다. 본 연구에서는 두 가지 방법을 모두 사용하여 착륙 임무 시나리오를 시뮬레이션을 수행한 후 장단점을 비교분석하였다. 달 주차궤도를 이용한 착륙은 달고도 100km에서 공전을 하다가 고도 15km까지 하강한 후 Powered descent 단계를 통해 착륙지에 착륙하는데 Powered descent 단계는 다시 감속단계, 접근 단계, 최종 하강 단계로 나뉘어진다. 달 착륙선은 나로우주센터에서 KSLV-2에 실려 2025년에 발사되며, 달 착륙지는 달의 과학적 임무를 고려하여 달 남극 근처로 가정하였다. 달 착륙 시뮬레이션을 통해 달 착륙선의 비행 궤적과 필요한 연료량 계산 등의 정보를 통해 직접 착륙 방법과 달 주차궤도를 이용하는 방법의 장단점을 확인할 수 있었다.

• Current Industrial and Technological Trends in Aerospace
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• v.8 no.1
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• pp.62-76
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• 2010

In this paper, recent researches about the unmanned lunar lander development are studied. Objectives of this study are to derive research trends and to identify key design activities especially in early design phase of unmanned lunar lander. Case study covers SELENE-2 of Japan, LEDA and MoonNEXT of ESA, and small and modular spacecraft approach of NASA. Lunar lander concepts proposed for the International Lunar Network Anchor Nodes are also studied. For each lunar lander program, mission requirements are summarized and mission design results are reviewed. Approaches of safe lunar landing including design of navigation, guidance and control, combination of sensors, derived sensor and propulsion performance requirements are also analyzed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.4
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• pp.324-331
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• 2018

The thermal environment on lunar surface is more severe than that of earth's surface or low earth orbit because of the long daytime and nighttime due to 28 days of rotation cycle of moon. Thus, analyzing heat flux on lunar lander at potential landing sites is important to determine the landing site in its initial design phase. In this study, thermal model of lunar regolith that can simulate lunar surface temperature was constructed for analyzing thermal characteristics according to the potential landing sites of lunar lander. The heat flux analyses were performed various latitudes of equator, mid-latitude, polar regions, lunar mare and highland. In addition, we also investigated the heat flux of lunar lander when it is landed on adjacent area to hill.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.193.2-193.2
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• 2012

달착륙선 등과 같은 특수 목적을 위해 제작된 우주용 착륙선에는 착륙 시 전달되는 충격하중이 탑재장비로 전달되지 못하도록 연착륙(soft-landing)을 위한 충격흡수 메커니즘이 구현되어 있어야 한다. 일반적으로 자동차 및 항공기에서는 실린더와 피스톤으로 구성된 유공압식 완충장치를 주로 사용하여, 피스톤 압축으로 실린더 내부 오일 또는 압축공기가 오리피스를 통하여 분출됨에 따라 유체마찰 에너지를 활용한 충격 흡수장치가 일반적이다. 그러나 이와 같은 지상 장비용 유공압식 충격흡수 메커니즘은 진공 및 무중력 우주 환경하에서 오리피스 기능 상실, 유압유 기화 현상 및 극저온/고온 환경에서의 성능저하 등의 문제점으로 인하여 우주용 착륙선 충격완충장치로 적용이 불가능하다. 따라서 기존의 우주용 착륙선의 대부분은 충격에너지를 기계적인 좌굴 소성 변형에너지로 변환하여 충격을 흡수할 수 있도록 알루미늄 허니콤을 주로 많이 사용하여 왔다. 본 연구에서는 진공 및 무중력 우주환경에서 착륙선 충격완충 장치로 적용이 가능하도록 실리콘 포옴과 스프링을 조합하여 구성하였으며, 충격완충 매체로 유압유 및 공압을 대체할 수 있도록 실리콘 포옴을 후방 사출 성형 방식으로 적용하여 오리피스를 통과한 실리콘 포옴의 변형에너지로 충격에너지를 흡수하게 함으로서 착륙 완충효율을 극대화 할 수 있도록 검토하였다.

• Current Industrial and Technological Trends in Aerospace
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• v.9 no.1
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• pp.119-129
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• 2011

The soft landing of a lunar lander after the entrance of lunar orbit is an essential prerequisite for the accomplishment of the lander's lunar mission. During the landing process of a lunar lander, efficient shock absorption and stability maintenance are indispensible technology to protect payloads. Therefore, the landing gear is a crucial structural component of a lunar lander, it has to absorb the kinetic energy associated with touchdown and support the static load of the landing module in an upright position. In this paper, various landing gears of lunar landers which are being developed as well as which had been successfully landed on the moon surface are investigated. In the end, the Korean lunar lander, which is being designed for preliminary development model, is presented as an example of the lunar lander development.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.9
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• pp.734-745
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• 2017

The navigation system of lunar lander are composed of various navigation sensors which have a complementary characteristics such as inertial measurement unit, star tracker, altimeter, velocimeter, and camera for terrain relative navigation to achieve the precision and autonomous navigation capability. The required performance of sensors has to be determined according to the landing scenario and mission requirement. In this paper, the specifications of navigation sensors are investigated through covariance analysis. The reference error model with 77 state vector and measurement model are derived for covariance analysis. The mission requirement is categorized as precision exploration with 90m($3{\sigma}$ ) landing accuracy and area exploration with 6km($3{\sigma}$ ), and the landing scenario is divided into PDI(Powered descent initiation) and DOI(Deorbit initiation) scenario according to the beginning of autonomous navigation. The required specifications of the navigation sensors are derived by analyzing the performance according to the sensor combination and landing scenario.

• The Science & Technology
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• v.9 no.7 s.86
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• pp.8-8
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• 1976

미국화성탐색선 "바이킹" 1호가 7월 20일 오후 8시 53분(한국시간) 드디어 화성 크리세 플래니티아(황금의 땅)에 착륙성공하였다. 10억여불이 투자된 "바이킹" 1호의 주목적은 화성에 생명체가 있는가를 과명하는데 있다. 모선인 바이킹궤도순회선과 자선인 화성 착륙선은 화성을 감싸고 있는 신비의 너울을 벗기기 위한 과학적 시험을 하게된다. 궤도순회선은 영상화시험, 적외선 열지도 작성, 수증기검출 무선과학을 위한 시험을 담당하게 되며 착륙선은 화성표면, 대기권, 기타 천문학연구, 대상물체의 영상하시험, 무기화학시험관측, 지진조사, 화성모래알의 자성시험을 하게된다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.2
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• pp.124-132
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• 2018

In this paper, landing stability evaluation of lunar lander considering various landing conditions was performed. The status of landing stability of the lunar lander is classified into stable landing, conditionally stable landing due to sliding and unstable landing due to tip-over. In particular, the quasi-static tip-over equation was rearranged considering the phenomena of lowering the center of gravity and extension of foot-pad interval of the landing gear. These results were compared by finite element model analysis results using a commercial software ABAQUS and its validity and accuracy were verified. The verified finite element model was used for examining the tendency of various environmental variables such as landing conditions, friction coefficient, lateral speed and slope of ground.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.12
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• pp.1184-1194
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• 2010

The descent and ascent phases for a lunar lander are composed of several phases. Accordingly, the constraints and control values adequate for each phase are required in order to generate optimal lander's trajectory. The optimal trajectories for descent and ascent phases are generated by the cost function to minimize fuel consumption & attitude variation rates. In this paper, the optimal control problem to make trajectory uses Gauss pseudo-spectral method which is one of the direct approach method. This problem generates lander's reference trajectory, states and controls.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.2
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• pp.167-174
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• 2018

The heater is applied to the lunar lander for securing its survivability under severe lunar thermal environment during 14 days of night time. For this, the heater on/off set-points shall be determined to minimize the power consumption due to the limited power generation of lunar lander during night time. In addition, the temperature changes of the lander according to the heater set-point is also an important factor because it is related to thermo-mechanical reliability on solder joint of on-board electronics. In this study, we investigated thermo-mechanical reliability on solder joint according to the heater set-point by using commercial reliability and a life prediction tool of Sherlock based on the thermal analysis results of lunar lander that is a year of the mission lifetime.