• International Journal of Aeronautical and Space Sciences
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• 제15권3호
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• pp.267-280
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• 2014

A spacecraft placed in an Earth-Moon L2 quasi-halo orbit can maintain constant communication between the Earth and the far side of the Moon. This quasi-halo orbit could be used to establish a lunar space station and serve as a gateway to explore the solar system. For a mission in an Earth-Moon L2 quasi-halo orbit, a spacecraft would have to be transferred from the Earth to the vicinity of the Earth-Moon L2 point, then inserted into the Earth-Moon L2 quasi-halo orbit. Unlike the near Earth case, this orbit is essentially very unstable due to mutually perturbing gravitational attractions by the Earth, the Moon and the Sun. In this paper, an insertion maneuver of a spacecraft into an Earth-Moon L2 quasi-halo orbit was investigated using the global optimization algorithm, including simulated annealing, genetic algorithm and pattern search method with collision avoidance taken into consideration. The result shows that the spacecraft can maintain its own position in the Earth-Moon L2 quasi-halo orbit and avoid collisions with threatening objects.

• 한국항공우주학회지
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• 제38권7호
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• pp.684-692
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• 2010

본 논문에서는 지구-달 천이를 위한 최적 궤도 설계에 관한 연구를 수행하였다. 지구와 달의 인력을 동시에 고려한 평면상 제한 3체 궤도 운동 모델을 바탕으로 지구 출발시에는 순간 추력을, 지구-달 천이 과정 및 달 임무궤도 투입시에는 연속 추력을 사용하는 혼합형 궤도전이 방법을 제시하였다. 최적화 풀이 방법으로서 Direct Transcription 및 Collocation을 이용한 비선형 프로그래밍 기법을 적용하였으며, 지구 출발 및 달 임무궤도 투입 궤적의 형상은 순간 추력의 연속 추력에 대한 상대 가중치 및 비행시간에 의하여 매우 달라질 수 있음을 파악하였다.

• 한국과학교육학회지
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• 제15권4호
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• pp.379-393
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• 1995

In spite of school science learning, the students' conceptions have not been changed easily. Therefore, to make students overcome their non scientific conceptions has been an important issue in science education. The purpose of this study was to identify the conceptions of students and teachers on the motion of the earth and the moon. The instrument was developed for estimating students' understandings of the concepts related to the motion of the earth and the moon. The validity of the instrument was examined by the specialists in Science Educator and Astronomer. At the same time, the two field trials had been executed, and the items were modified. Also, it consists of 12 items including 9 two-tier multiple choice items and 3 multiple choice items. The population of this study consists of 250 eighth-, 299 tenth-, 292 eleventh-grade students, 134 science teachers in secondary school. SPSS/PC+ was adopted for the statistical analysis. The type of misconceptions possessed students were as follows: 1) At 12:00 noon, the sun is directly overhead. 2) First quarter moon is a half of overall surface of the moon. 3) Air don't rotate with the earth surface because it keeps apart from the earth surface. 4) Summer is warmer than winter, because the earth is nearer from the sun in summer. 5) Whenever season is changed, the direction of rotation axis of the earth is changed. 6) The moon is the brightest at the position of new moon, because the distance between the moon and the sun is the shortest and the moon is received strongest sunlight. 7) The moon is not seen at the position of real full moon, because it is covered with shadow of the earth. 8) When the moon is not seen in the earth, sunlight is not reached at the moon. The major findings were as follows : 1) The middle school students had more misconceptions than those of high school students. And female students had more misconceptions than those of male ones. 2) The rate of correct answer and the type of conception in the tenth grade students were very similar with eleventh grade students. 3) The higher cognitive level, the better development of scientific conception and the less misconception. Also, the correlation coefficient between scientific conception score and GALT score was 0.57. 4) The students in scientific part had higher the rate of correct answer than those of students in human part and the former had less misconception than the latter. 5) The rate of correct answer about model and figure items was lower than descriptive ones, because they did not understand about figures itselves. These types of misconceptions will be used for science instruction and studies of other conceptions need.

• 천문학회지
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• 제45권2호
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• pp.49-57
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• 2012

In this study, I calculate the past and future dynamical states of the Earth-Moon system by using modified Lambeck's formulae. I find that the ocean tidal effect must have been smaller in the past compared to its present amount. Even though the Moon is already in the spin-orbit synchronous rotational state, my calculation suggest that it will not be in geostationary rotational state in the next billion years or so. This is due to the associated Earth's obliquity increase and slow retardation of Earth's spin and lunar orbital angular velocities. I also attempt to calculate the precessional period of the Earth in the future. To avoid uncertainties in the time scale, the future state is described by using the Earth-Moon distance ratio as independent parameter. Effects due to solar tidal dissipation are included in all calculations.

• 대한자원환경지질학회:학술대회논문집
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• 대한자원환경지질학회 2000년도 춘계 공동학술발표회
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• pp.83-83
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• 2000

• Coupled systems mechanics
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• 제7권5호
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• pp.611-626
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• 2018

We theoretically consider a possible influence of periodic oceanic tides on non-periodic changes in the dynamics of the Earth and Moon over a long time scale. A particular emphasis will be placed on the contribution from rotating tidal waves, which rotate along the inner edge of an oceanic basin surrounded by topographic boundary. We formulate the angular momentum and the mechanical energy of the rotating tidal wave in terms of celestial parameters with regard to the Earth and Moon. The obtained formula are used to discuss how the energy dissipation in the rotating tidal wave should be relevant to the secular variation in the Earth's spin rotation and the Earth-Moon distance. We also discuss the applicability of the formula to general oceanic binary planets subject to tidal coupling.

• 한국지구과학회지
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• 제32권5호
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• pp.514-520
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• 2011

As homework, a total of 32 seventh grade science-gifted students were asked to observe the moon at daily intervals for one month duration. They were also asked to take the photos and to record relevant variables in a given format. The purpose of the task was to investigate what students thought, as they observed the moon. The results show that students paid attention mainly to the position of the moon relative to other variables such as the date in the lunar calendar, the observer's position on the earth, and the position of the sun. Overall students' response implied that students did not observe the lunar phase in relation with relevant variables. Some reponses from students show common misconceptions such as the cause of the lunar phase to reflect the shadow of the earth. However, some responses reveal students' idea that has been rarely reported in the previous researches. For example, some students drew the moon to revolve in the opposite direction. Significant number of students drew the sun's position to be due west before the full moon and due east after the full moon. Few students recognized the relation between the time of observation and observer's position on the earth. The results of current research suggest that not only the education but also the research needs to be expanded to consider informal environment such as the actual field conditions.

• Journal of Positioning, Navigation, and Timing
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• 제12권4호
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• pp.335-342
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• 2023

Lunar Navigation Satellite System refers to a constellation of satellite providing PNT services on the moon. LNSS consists of main satellite and navigation satellites. Navigation satellites orbiting around the moon and a main satellite moves the area between the moon and the L2 point. The navigation satellite performs the same role as the Earth's GNSS satellite, and the main satellite communicates with the Earth for time synchronization. Due to the effect of the non-uniform shape of the moon, it is necessary to focus on the influence of the lunar gravitational field when designing the orbit simulation for navigation satellite. Since the main satellite is farther away from the moon than the navigation satellite, both the earth's gravity and the moon's gravity must be considered simultaneously when designing the orbit simulation for main satellite. Therefore, the main satellite orbit simulation must be designed through the three-body problem between the Earth, the moon, and the main satellite. In this paper, the orbit simulation tool for main satellite and navigation satellite required for LNSS was designed. The orbit simulation considers the environment characteristics of the moon. As a result of comparing long-term data (180 days) with the commercial program GMAT, it was confirmed that there was an error of about 1 m.

• 대한지구과학교육학회지
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• 제9권3호
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• pp.323-340
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• 2016

이 연구의 목적은 지구와 달의 공전 궤도를 고려한 달의 위상 변화 관찰 교구의 효과를 알아보고자 하는 것이다. 이를 위하여 지구의 공전 궤도와 $5^{\circ}$ 기울어진 달의 공전 궤도를 나타내는 달의 위상 변화 관찰 교구를 개발하였다. 그리고 이 교구의 효과를 확인하기 위해 제주시내 초등학교 6학년 110명의 학생을 실험집단과 비교집단으로 나누어 연구를 실시하였다. 실험집단 55명의 학생은 이 연구에서 개발한 달의 위상 변화 관찰 교구를 활용하여 수업을 진행하였고 비교집단 55명의 학생은 현행 교과서 활동으로 수업을 진행하였다. 실험집단과 비교집단의 학생들에게 달의 위상 변화에 대한 사전, 사후, 지연 개념검사와 개념수준별 반구조화된 면담을 실시하였다. 학생들의 응답에 따라 '위상 인지', '우주적 관점', '지구적 관점', '인지 불가'로 개념 수준을 구분하였다. 사전개념검사에서 t-검정 결과 실험집단과 비교집단은 동질 집단임을 확인할 수 있었다. 사후개념검사와 지연개념검사에서 실험집단은 비교집단보다 통계적으로 유의미하게 높은 점수를 얻었다. 또한 실험집단은 비교집단보다 상위 개념 수준인 '위상 인지'에 속하는 학생 수가 많았다. 반구조화된 면담 결과 '위상 인지'와 '우주적 관점'에 속한 실험집단 학생들은 비교집단 학생들보다 달의 위상 변화에 대해 더 과학적으로 설명하였다. 이를 통해 지구와 달의 공전 궤도를 고려한 달의 위상 변화 관찰 교구가 효과가 있음을 확인할 수 있다.

• 한국과학교육학회지
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• 제33권1호
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• pp.193-207
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• 2013

이 연구는 지구와 달 표면에서 물체의 운동에 대한일반 중학생들과 과학영재학생들의 개념을 조사하였다. 연구 대상은 일반 중학교 중학생 1학년 61명, 2학년 51명, 3학년 51명 총 163명과 대학부속 과학영재교육원 중등 과학영재학생 32명으로 하였다. 연구 내용은 지구와 달 표면에서 연직, 경사면, 수평면에 따른 물체의 운동에 대한 개념으로 하였다. 각각 지구와 달 표면에서 크기는 같고 질량이 다른 두 물체를 동시에 놓거나, 같은 속력으로 위쪽으로 던지거나, 수평면에서 굴렸을 때 '어느 것이 먼저 도착하는가?'를 조사하였다. 지구와 달 동시 상황에서는 같은 물체를 지구와 달 표면에서 동시에 놓거나, 던지거나, 굴렸을 때 '어느 장소에 먼저 도착하는가?'를 조사하였다. 연구결과 과학영재학생들이 일반 중학생들 보다 지구 표면에서 연직, 경사면, 수평면의 모든 조건에서 물체의 운동에 대한 개념에 유의미한 차이가 있었고, 달 표면에서 연직 위 방향에서 물체의 운동에 대한 개념에 유의미한 차이가 있었다. 지구와 달 표면 동시 상황에서는 연직 아래 방향에서 물체의 운동에 대한 개념에 유의미한 차이는 없었고, 연직 위 방향, 경사면, 수평면에서 물체의 운동에 대한 개념에 유의미한 차이가 있었다. 연구 결과를 통해서 얻은 결론은 첫째, 지구와 달 표면에서 물체의 운동에 대한 설명을 할 때 진공에 대한 의미와 중력의 크기에 대한 학습이 먼저 이루어져야 한다. 둘째, 중학생들에게 다양한 상황과 조건에서 물체의 운동을 통합적으로 이해하도록 지도해야한다. 셋째, 중학생들은 상황을'동일시'하려는 사고 경향이 있다. 마지막으로 힘과 물체의 운동은 물리 영역에서 매우 중요한 단원이며, 교사가 물체의 운동을 설명할 때 위 결과들을 유념해서 가르쳐야 한다.