• 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.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.04a
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• pp.65-69
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• 1994

전철의 궤도 방진에 의한 소음.진동 저감 효과를 실제 측정에 의해 확인하기 위해서는 궤도 방진 전과 후의 소음.진동 측정 데이타가 필요하다. 그러나 방진 궤도 구조로 설계된 신축 역사는 전철이 운행되지 않으므로 궤도 방진 전의 전철 운행시 발생하는 소음.진동을 측정할 수 없으며 공사완료 후 전철이 운행된다고 하여도 궤도 방진이 되지 않은 상태에서의 소음.진동 측정은 불가능하다. 따라서 본 연구에서는 현재 전철이 운행되고 있고 궤도 방진이 되어 있지 않은 유사한 구조의 산본 전철 역사를 선택하여 소음.진동을 측정, 분석하고 이 데이타를 방진 궤도 구조로 설계된 유사한 구조 신축 역사의 소음.진동을 예측하는데 기초 입력 데이타로 제시하고자 한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.12
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• pp.867-875
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• 2022

The preliminary mission analysis of a lunar lander, which is mounted on the upper stage of a Korean space launch vehicle, is performed when landing on the moon through a trans-lunar injection maneuver after being injected into the earth's low orbit by th launcher in this paper. Both direct landing and orbital landing methods, which have each advantage and disadvantages, are applied and their transfer orbit characteristics are analyzed according to the launch date when launching in lunar October 2030. We also analyzed the launch dates which satisfying eclipse conditions, solar elevation conditions, and tracking time intervals such as the US lunar lander Surveyor-1. The obtained results show that the most appropriate launch date is the 4th day of lunar October in case of direct landing method, and the 3rd day in case of indirect landing method, since the argument of perigee of the trans-lunar injection orbit and eclipse conditions are favorable in the dates.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.9
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• pp.775-783
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• 2017

In this paper, an impulsive rendezvous problem by using minimum energy of spacecraft in different orbits is addressed. In particular, the orbits considered in this paper are the general orbits including the elliptic orbit, while most of the orbits considered in the literature have been restricted within co-planar or circular orbits. The constraints for solving this optimization problem are the Kepler's equation formulated with the universal variable, and the final position and velocity of two spacecraft. Also, the Lagrange coefficients, sometimes called as f and g solution, are used to describe the orbit transfer. The proposed method technique is demonstrated through numerical simulation by considering the minimum energy, and both the minimum energy and the wait time, respectively. Finally, it is also verified by comparing with the Hohmann transfer known as the minimum energy trajectory. Although a closed-form solution cannot be obtained, it shows that the suggested technique can provide a new insight to solve various orbital transfer problems.

• Journal of Astronomy and Space Sciences
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• v.7 no.1
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• pp.37-45
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• 1990

It was investigated that the effect of zonal harmonics to transfer orbit. Since parking orbit is located at low altitude, the zonal harmonics affects transfer orbit relatively high sense. So under the zonal harmonics, eccentricity and semi-major-axis which were related orbit altitude at the first hand, were investigated. As a result the zonal harmonics increases the altitude of apogee of transfer orbit. So if the zonal harmonics is considered in orbit transfer the fuel can be saved a little.

• Aerospace Engineering and Technology
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• v.6 no.2
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• pp.96-103
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• 2007

A program for LAE (liquid Apogee Engine) firing strategy calculation was developed. This program can be used as the first stage of transfer orbit analysis, which process receives input parameters as like initial orbit elements, ground TT&C stations positions, satellite performances and makes firing user-selectable strategies. The developed program is dedicated to GEO satellites which using LAE generally and it can calculate six back-up strategies and deals situation its maximum firing number is six. The MS-EXCEL software was used for the input and output process. And the numerical calculation part was embodied with MATLAB functions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.7
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• pp.684-692
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• 2010

Based on the planar restricted three body problem formulation, optimized trajectories for the Earth-Moon transfer are obtained. Mixed impulsive and continuous thrust are assumed to be used, respectively, during the Earth departure and Earth-Moon transfer/Moon capture phases. The continuous, dynamic trajectory optimization problem is reformulated in the form of discrete optimization problem by using the method of direct transcription and collocation, and then is solved using the nonlinear programming software. Representative results show that the shape of optimized trajectory near the Earth departure and the Moon capture phases is dependent upon the relative weight between the impulsive and the continuous thrust.

• Bulletin of the Korean Space Science Society
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• 1995.10a
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• pp.39-39
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• 1995

• Proceeding of EDISON Challenge
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• 2014.03a
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• pp.211-224
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• 2014

금속을 포함한 분자에 대한 양자계산은 정확하고 일관된 결과를 얻기가 힘들 뿐만 아니라 상당한 컴퓨터 자원을 소비하며 많은 시간이 소요된다. 본 연구에서는 복잡한 양자계산의 근사를 위한 방법으로 본래 정성적인 구조 예측에 사용되는 닮은 궤도함수분석(Isolobal Analysis)을 정량적인 측면에서 접근해보고, 이를 통해 닮은 궤도(Isolobal) 구조를 가지고 있는 단위들(radical 등)에 대해서 계산을 근사할 수 있는 방법에 대해 논의한다. $CH_3$, $CH_2$와 닮은 궤도 구조를 가진 전형 원소를 중심으로 하는 분자들에 대해 가장 기초적인 근사계산인 Hartree-Fock 양자계산을 수행하였다. $(CUH_5){_2}^{2-}$를 표적으로 결합 구조를 예측하기 위한 경향성을 계산한 결합 성질로부터 파악한다. 분석 결과 동일한 주기에 대해서는 원자반지름(Atomic radii)에 대해 조화 형태의 결합에너지가 얻어졌으며, 동일한 족에 대해서는 좋은 근사가 되지 않았다. 파악된 경향성을 바탕으로 금속의 결합을 근사한 에너지에 대해서는 -1054.1875 kJ/mol로 비교적 큰 오차를 보였으나, 오차 항에 대한 분석이 가능해 추가적인 계들에 대한 계산으로 근사를 교정할 수 있을 것으로 보인다.

• Proceedings of the Optical Society of Korea Conference
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• 2004.07a
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• pp.58-59
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• 2004