• Journal of Satellite, Information and Communications
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• v.11 no.1
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• pp.58-62
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• 2016

The satellite propulsion system provides the required thrust to insert a satellite into the desired orbit after separation from the launch vehicle and to control orbit inclination or compensate altitude loss due to drag after inserted into the desired orbit. The on-orbit performance of LEO satellite propulsion system according to operation mode was verified based on the results analysis for early on-orbit operation. The temperature trends of components and tubing were checked and the resultant trends were within the normal range as well.

• Aerospace Engineering and Technology
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• v.10 no.2
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• pp.65-73
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• 2011

After launch, in order to inject the geostationary satellite into its operational orbit, the perigee altitude are forced to be raised to geostationary altitude by firing onboard LAE(Liquid Apogee Engine) at apogee of the transfer orbit. In this process, the LAE burn is divided into three or four separated burns in order to control the orbit very precisely by giving feedback the determined orbit informations and to inject the satellite in predefined longitude. This paper proposes an algorithm to determine LAE firing time slots and ${\Delta}V$ vectors under assumption of impulsive LAE burning, and additionally, a method to compensate errors induced by continuous burning. And computer simulations have been performed to validate proposed algorithms.

• 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

• Product Safety
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• s.56
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• pp.53-63
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• 1997

• Aerospace Engineering and Technology
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• v.13 no.1
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• pp.184-192
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• 2014

In this paper, the lifetime of the artificial space objects in the LEO is analysed by using TLE data, which is provided by JSpOC. We observed the change of the number of space objects from 1957 and determined the reason of space debris generation. And then, we performed the analysis about present condition of space debris environment. The lifetime analysis includes a total of 11,792 artificial space objects and performed until the year 2050 by orbit propagation. We analyze the annual reentry frequency for the high RCS objects such as nonoperational satellites and rocket bodies, which have the possibility of earth ground impact through STK/Lifetime Tool for accurate and effective calculation. The results show that 9 payloads or rocket bodies will be decayed annually and 2 or 3 objects of total value have the possibility of ground impact. In addition, it is also shown that the 40% of a total analysed objects have the lifetime over 200 years.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.1
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• pp.17-23
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• 2020

Upper stage of launch vehicle mainly injects a lunar explorer from low earth orbit to the moon at a distance of 380,000 km. In foreign lunar explorer, the upper stage is separated from the explorer after the explorer is injected into the earth-moon transfer trajectory, and the lunar explorer then uses on-board propellant to carry out mid-course correction maneuvers and lunar orbit insertion maneuvers. This study describes a newly presented small liquid upper stage. Using a small liquid upper stage with a wet mass of 2.9 tonnes, the lunar explorer not only can be injected earth-moon transfer trajectory but also can be performed lunar orbit insertion. This study provides acceptable mass range of the lunar explorer and the scope of acceptable mission range also describes based on the launch from Naro Space Center.

• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.95-102
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• 2005

This paper introduces the LAE(Liquid Apogee Engine) and station acquisition fuel budget estimation method for the COMS(Communication, Ocean and Meteorological Satellite) of Korea which is planned to be launched in 2008. And the estimation results are also presented. A statistical approach, more specifically, the Monte-Carlo method was employed to have the estimation include the effect of the launch vehicle GTO injection accuracies. A case study was conducted for several potential launch vehicles to compare the fuel requirements.

• Digital Contents
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• no.2 s.81
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• pp.38-39
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• 2000

21세기에는 인터넷방송 시대가 본격 열릴 전망이다. 지상파 방송 3사를 비롯해 언론사, 케이블TV업체,PC통신업체, 대기업, 인터넷업체 등이 경쟁적으로 인터넷방송국을 설립하거나 이를 적극 추진하고 있기 때문이다. 캐티즌으로 불리는 인터넷방송 시청인구도 인터넷 보급확산에 힘입어 기하급수적으로 증가하는추세를 보이고 있다. 이에 따라 인터넷방송 시장은 유망 인터넷 비즈니스의 한 분야로 자리하면서 본격적인 성장궤도에 진입할 것으로 보는 시각이 지배적이다. 21세기 뉴미디어로 불리며 크게 주목 받고 있는 인터넷방송의 현황과 과제를 살펴봤다.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.136.2-136.2
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• 2012

저궤도지구관측 위성의 광학탑재체는 위성이 궤도에 진입한 이후 관측과 같은 주요 임무를 전담하는 중요 시스템이다. 광학탑재체가 장착된 위성이 발사체에 탑재되어 발사하는 순간부터 우주의 궤도에 진입하기까지 극심한 진동 환경에 노출된다. 이러한 상황을 예측하여 설계된 해당 시스템은 발사 이전에 진동 환경을 모사하는 시험을 통해 완벽하게 검증되어야 한다. 본 논문에서는 저궤도지구관측위성용 광학탑재체에 대하여 실시한 진동 환경 시험 방법 및 분석 내용을 소개하고자한다.

• Aerospace Industry
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• s.104
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• pp.40-41
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• 2009

지난 8월 25일 온 국민의 관심 속에 대한민국 최초의 우주발사체 나로호가 힘차게 하늘로 솟아올랐다. 그러나 최종적으로 과학기술위성 2호의 궤도 진입에는 실패함으로서 큰 아쉬움을 남겼다. 대한민국 우주개발의 신호탄이며 절반의 성공으로 평가되는 나로호 발사 과정을 되짚어 봤다.