• International Journal of Aeronautical and Space Sciences
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• v.13 no.4
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• pp.421-427
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• 2012

Solar Sail propulsion has been validated in space (IKAROS, 2010) and soon several more solar-sail propelled spacecraft will be flown. Using sunlight for spacecraft propulsion is not a new idea. First proposed by Frederick Tsander and Konstantin Tsiolkovsky in the 1920's, NASA's Echo 1 balloon, launched in 1960, was the first spacecraft for which the effects of solar photon pressure were measured. Solar sails reflect sunlight to achieve thrust, thus eliminating the need for costly and often very-heavy fuel. Such "propellantless" propulsion will enable whole new classes of space science and exploration missions previously not considered possible due to the propulsive-intense maneuvers and operations required.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.624-628
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• 2003

Lanthanum oxyfluoride can be synthesized by mechanochemical (MC) reaction between lanthanum oxide ($La_2O_3$) and polytetrafluoroethylene (PTFE, ($({CF_2CF_2}_n)$) in air using a planetary mill. MC reaction between the two materials induced from intensive grinding operation. The MC reaction is almost finished by 240min, and the products ground for 240min or more are composed of LaOF, amorphous $La(CO_3)F$ and amorphous carbon (C). Heating this MC reaction products at $600^{\circ}C$ enables us to eliminate amorphous C and decompose $La(CO_3)F$ into LaOF, so that pure LaOF material can be obtained as the final product. The average particle size of the final product (purified LaOF) is around few ten nanometers.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.7
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• pp.558-565
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• 2017

Recently, there has been a tendency to lead the private sector in the launch vehicle market, and as the market has become saturated, efforts are being made to reduce the launch cost. Advanced countries in space development have promoted manned long-range space exploration plans. As oxygen/methane is more efficient, lower cost, and eco-friendly than typical propellants, and can be produced locally on an alien planet, it is the most suitable next-generation propellant to meet this trend. Now methane engine development is accelerating due to changes in international conditions and corporate environment. It is also expected to develop a methane engine in order to survive in this global trend and to keep up with the launch vehicle market in the future.

• Journal of Astronomy and Space Sciences
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• v.40 no.4
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• pp.199-215
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• 2023

The Korea Pathfinder Lunar Orbiter (KPLO), the first South Korea lunar exploration probe, successfully arrived at the Moon on December, 2022 (UTC), following a 4.5-month ballistic lunar transfer (BLT) trajectory. Since the launch (4 August, 2022), the KPLO magnetometer (KMAG) has carried out various observations during the trans-lunar cruise phase and a 100 km altitude lunar polar orbit. KMAG consists of three fluxgate magnetometers capable of measuring magnetic fields within a ± 1,000 nT range with a resolution of 0.2 nT. The sampling rate is 10 Hz. During the originally planned lifetime of one year, KMAG has been operating successfully while performing observations of lunar crustal magnetic fields, magnetic fields induced in the lunar interior, and various solar wind events. The calibration and offset processes were performed during the TLC phase. In addition, reliabilities of the KMAG lunar magnetic field observations have been verified by comparing them with the surface vector mapping (SVM) data. If the KPLO's mission orbit during the extended mission phase is close enough to the lunar surface, KMAG will contribute to updating the lunar surface magnetic field map and will provide insights into the lunar interior structure and lunar space environment.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.161-164
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• 2012

We performed a spectroscopic survey for cometary volatiles with the Infrared Camera onboard the Japanese infrared satellite AKARI. The observations were carried out in the near-infrared wavelength range in the period from 2008 June to 2010 January. In this paper, we summarize the observations and results of the AKARI survey for the mixing ratios of major volatiles in comets. We derived the $2.5-5{\mu}m$ spectra of 18 comets including both Oort cloud comets and Jupiter-family comets. Prominent emission bands in the observed spectra are the fundamental vibrational bands of water ($H_2O$) at $2.7{\mu}m$ and carbon dioxide ($CO_2$) at $4.3{\mu}m$. The fundamental vibrational band of carbon monoxide (CO) at $4.7{\mu}m$ and the broad emission feature probably related to C-H bearing molecules can also be recognized around the $3.4-3.5{\mu}m$ region in some comets. We detect $CO_2$ in 17 out of 18 comets, and derived gas production rate ratios of $CO_2$ with respect to $H_2O$ in 17 comets. We detect a reliable CO emission band only in three of the comets. Our data set provides the largest homogeneous database of $CO_2/H_2O$ ratios in comets obtained so far.

• Journal of Astronomy and Space Sciences
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• v.34 no.3
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• pp.213-223
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• 2017

The deep space orbit determination software (DSODS) is a part of a flight dynamic subsystem (FDS) for the Korean Pathfinder Lunar Orbiter (KPLO), a lunar exploration mission expected to launch after 2018. The DSODS consists of several sub modules, of which the orbit determination (OD) module employs a weighted least squares algorithm for estimating the parameters related to the motion and the tracking system of the spacecraft, and subroutines for performance improvement and detailed analysis of the orbit solution. In this research, DSODS is demonstrated and validated at lunar orbit at an altitude of 100 km using actual Lunar Prospector tracking data. A set of a priori states are generated, and the robustness of DSODS to the a priori error is confirmed by the NASA planetary data system (PDS) orbit solutions. Furthermore, the accuracy of the orbit solutions is determined by solution comparison and overlap analysis as about tens of meters. Through these analyses, the ability of the DSODS to provide proper orbit solutions for the KPLO are proved.

• The Journal of Asian Finance, Economics and Business
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• v.5 no.4
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• pp.173-185
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• 2018

At a turn of the third millennium the world storms and quickly changes. It became difficult to expect what expects us tomorrow. The most important are questions of recovery from the crisis and rescue of mankind from forthcoming global changes: warming of climate, water and food problems, social, economic and political conflicts that are shaking the world and other various cataclysms, accidents, negative processes. It puts before mankind the problem which never solved by our civilization. All this is caused by ignoring of objective economic laws, laws of wildlife and also by violation of cyclic development management's laws. In article the concept of strategy of mankind's survival in XXI and next centuries, the principles of creation of planetary house of universal civilization for post-industrial world based on spirituality scientific and technological revolutions, ecology, space exploration, economy and world safety are considered. Introduction of uniform universal measurement of currency for the whole world in the form of "power" is offered. Important aspect of a research is theoretical postulate on integrated innovative society. The author puts forward a new paradigm of government on a basis of 5 spirals. The basic model of forced development of small and medium business, including 9 projects, is developed.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.45.1-45.1
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• 2018

We present observational evidence of the surface homogeneity on Phaethon based on the time-series multi-band photometry and spectrometry. The observations of Phaethon were conducted in Nov.-Dec. 2017. We confirmed that Phaethon is a B-type asteroid, as was previously known, and its rotational color variation was not detected. During our observation period, the sub-solar latitude of this asteroid was approximately $55^{\circ}S$, corresponding to the southern hemisphere of the body. Thus, we found that the southern hemisphere of Phaethon has a homogeneous surface from our observation results. In addition, we compared our spectra with archival data to investigate the latitudinal surface properties of the asteroid. The result showed that it doesn't have a latitudinal color variation. To verify this assumption, we investigated its solar-radiation heating effect, and the result suggested that this asteroid underwent a uniform thermal metamorphism regardless of latitude, which is consistent with our observations. Based on this result, we discuss the homogeneity of the surface of the body.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.532-535
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• 2022

Path following algorithms have been intensively studied for various mobile platforms such as planetary exploration, unmanned delivery, and autonomous driving. However, ensuring high accuracy in practical applications is challenging due to enormous uncertainty inherent in real environment. In this paper, we aim to reveal the guideline for the design and implementation by investigating the path following performance of mobile robot controlled by the pure pursuit algorithm. To this end, we evaluate the accuracy of the pure pursuit algorithm when tuning the look ahead distance and deploying erroneous actuator.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.59.2-59.2
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• 2021

현재 우리나라는 달탐사 개발 사업을 통하여 2022년 8월 발사를 목표로 달 궤도선인 KPLO와 과학임무 및 기술검증 임무를 수행하게 될 임무 탑재체, 임무 수행을 위한 각종 소프트웨어의 개발, 궤도/궤적의 설계 등 일련의 개발 과정을 순조롭게 수행하고 있다. 또한 달 궤도선인 KPLO와 이들 탑재체에 대한 운영과 관제를 수행하는 KPLO 심우주 지상국도 일정에 따라 개발 막바지에 접어들고 있다. 특히 KPLO 심우주 지상국에는 우리나라 대학과 정부출연연구소에 의해서 개발되는 과학탑재체 4기가 달 궤도에서 과학임무를 수행하여 얻게되는 달 탐사 과학자료, 즉, 과학임무자료를 달 탐사에 직접 참여하는 과학자들뿐만 아니라 일반인들도 교육 및 연구에 활용할 수 있도록 달 탐사 과학자료의 저장, 공개, 관리를 위한 Archive system인 KARI Planetary Data System(KPDS)도 함께 개발되고 있다. KPDS는 전문 연구자와 일반인들이 별도의 교육없이 인터넷을 통하여 쉽게 접속하여 KPLO의 과학탑재체가 획득한 달 탐사 과학자료를 검색하여 내려받아 사용할 수 있도록 서비스를 제공할 예정이다. 본 논문에서는 과학탑재체 개발기관 소속의 연구자가 달 탐사 과학자료에 대한 검보정 처리와 과학적 분석을 수행하기 위해서 텔레메트리 형태의 원본형태의 과학자료를 KPDS로부터 다운로드 받는 과정과 검보정 처리가 된 과학자료를 일반 사용자들이 내려 받아 사용할 수 있도록 과학자료가 공개되기까지 일련의 과정을 설명하고, 연구자 및 일반사용자가 직접 접하게 되는 KPDS의 주요한 사용자 환경에 대해서 설명한다.