• Title/Summary/Keyword: 우주공간

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Application of Index form on the Robertson -Walker spacetime (Robertson-walker 시공간의 지표정리 응용)

  • Kim Mi-Suk;Yon Yong-Ho;Kim Mi-Hye
    • Proceedings of the Korea Contents Association Conference
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    • 2003.05a
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    • pp.470-473
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    • 2003
  • We have the index form of the multiply warped products manifold. From this result we will investigate the physical properties on the Robertson-Walker spacetime. The singularly thorem are usually interpreted as an indication that black hole exist and that there has been a big bang. This paper include necessary condition for the Robertson-Walker spacetime with singularly.

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Scientific Qualifications Reflected in the Exploration of Space Geometry Utilizing 4D Frame (4D 프레임을 활용한 공간도형탐구 담화에 나타난 과학적 소양)

  • Kim, Hwa-Soo
    • Journal of the Korean School Mathematics Society
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    • v.13 no.4
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    • pp.595-618
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    • 2010
  • To grow as talents with future oriented knowledge and creativity, students need imaginative power and creativeness, and to that end, mathematics and science subjects may help. Students need activities that help gain explorative mind for new things, concentrating ability, researching ability and creativeness, and such attributes can be improved through the activities of making various shapes utilizing space geometry in 4D-frame. Such activities not only contribute to defining ability in mathematics but also cherish the qualifications required as architects and space scientists.

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An Overview of Interplanetary Scintillation Method for Studying Solar Wind Physics (행성간 공간 섬광을 이용한 태양풍 연구에 대한 간단한 고찰)

  • 김수용;명노훈;최용석;김현구;김두환
    • Journal of Astronomy and Space Sciences
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    • v.5 no.2
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    • pp.123-127
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    • 1988
  • Interplanetary scintillation is the fluctuation produced in the apparent brightness of a radio source, due to refractive effects in the apparent brightness of a radio source, due to refractive effects in the turbulent solar wind flowing from the sun. If this medium is illuminated coherently, analysis of the spatial and temporal properties of the radiation reaching the earth allows the stochastic properties of the medium to be understood. Here, a brief review of method of interplanetary scintillation to study solar wind behavior will be introduced.

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Mission Analysis Involving Hall Thruster for On-Orbit Servicing (궤도상 유지보수를 위한 홀추력기 임무해석)

  • Kwon, Kybeom
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.48 no.10
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    • pp.791-799
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    • 2020
  • Launched in October 2019, Northrop Grumman's MEV-1 was the world's first unmanned mission demonstrating the practical feasibility of on-orbit servicing. Although the concept of on-orbit servicing was proposed several decades ago, it has been developed to various mission concepts providing services such as orbit change, station keeping, propellant and equipment supply, upgrade, repair, on-orbit assembly and production, and space debris removal. The historical success of MEV-1 is expected to expand the market of on-orbit servicing for government agencies and commercial sectors worldwide. The on-orbit servicing essentially requires the utilization of a highly propellant efficient electric propulsion system due to the nature of the mission. In this study, the space mission analysis for a simple on-orbit mission involving Hall thruster is conducted, which is life extension mission for geostationary orbit satellites. In order to analyze the mission, design space exploration for various Hall thruster design variable combinations is performed. The values of design variables and operational parameters of Hall thruster suitable for the mission are proposed through design space analysis and optimization, and mission performance is derived. In addition, the direction of further improvement for the current on-orbit mission analysis process and space mission analysis involving Hall thruster is reviewed.

ANALYSTS OF DAMAGE PROBABILITY FOR COLLISION BETWEEN SPACE DEBRIS AND A SATELLITE IN LOW-EARTH ORBIT (우주파편에 의한 저궤도 위성의 손상확률 분석)

  • Lee, Jae-Eun;Park, Sang-Young;Kim, Young-Rok;Choi, Kyu-Hong;Kim, Eung-Hyun;Kim, Gyu-Sun
    • Journal of Astronomy and Space Sciences
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    • v.24 no.2
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    • pp.135-144
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    • 2007
  • Space environment becomes more hazardous for satellite because of increasing number of space debris. This research is to analyze collision hazards between KOMPSAT 3 in low-earth orbit and space debris generated by the explosion of FengYun satellite on the January 11, 2007. Based on the observed data of the space debris from FengYun satellite, the mass and number distribution of the debris are estimated including undetectable debris from the explosion of FengYun satellite. The spatial density and flux for the space debris can be calculated according to size. This study also brings out the analysis for the assessment of collision probability and damage probability. The algorithm developed in the current paper can be used to estimate the level of risk due to space debris for the satellites that will be launched in the future.

Analysis on Mission Lifetime and Collision Avoidance of Cubesat Launched from ISS (ISS에서 발사되는 큐브위성의 임무수명 및 충돌회피 분석)

  • Yeom, Seung-Yong;Kim, Hongrae;Chang, Young-Keun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.5
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    • pp.413-421
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    • 2015
  • Since the first Cubesat was launched in 2003, there have been more than 230 Cubesats launched so far. Due to their small size and lightweight, Cubesats were launched by utilizing the empty space of regular launch vehicle. However, this launch method has a weakness that has been easily affecting by the schedule of major payloads. As a new solution to this problem, it has been proposed that a robot arm installed on ISS would be used to launch Cubesats. The orbits of Cubesat deployed from the ISS in various angles and directions are analyzed in this paper. We also analyze the possibility of collision between the Cubesat and ISS within the operational orbit of the CubeSat and eventually calculate the optimal angle of a robot arm, which maximizes the lifetime of Cubesat and minimizes the risk of collision between the Cubesat and ISS.

대전광역시 도시화 패턴 분석을 위한 원격탐사 자료 처리 및 다중시기 토지이용 현황도 제작

  • Kim, Youn-Soo;Lee, Kwang-Jae;Jeon, Gap-Ho
    • Aerospace Engineering and Technology
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    • v.3 no.2
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    • pp.141-148
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    • 2004
  • The importance of satellite data for numerous applications is stressed by the fact that many countries have given the development of space technologies very high priority. Among these, Korea has established a medium-term space development strategy to promote space development both on a scientific as well as commercial level. As part of this strategy, the first operational earth-observation, multi-purpose satellite(KOMPSAT-1) was launched successfully in December, 1999. The Electro-Optical Camera (EOC) on board of KOMPSAT-1 supplies panchromatic images with a spatial resolution of 6.6m Until April, 2004, it collected over 150.000 images of the Korean Peninsula and the rest of the world. This paper examines the use of remote sensing data to analyze urban growth in the city of Daejeon from 1960 to 2003. By using visual interpretation, land use maps are created.

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MIRIS 지구관측 적외선카메라 인증모델 성능 시험 및 Field Test

  • Mun, Bong-Gon;Park, Yeong-Sik;Lee, Chang-Hui;Park, Seong-Jun;Cha, Sang-Mok;Lee, Dae-Hui;Jeong, Ung-Seop;Nam, Uk-Won;Park, Jang-Hyeon;Yuk, In-Su;Ga, Neung-Hyeon;Lee, Mi-Hyeon;Lee, Deok-Haeng;Yang, Sun-Cheol;Kim, Yeong-Ju;Lee, Gi-Hun;Jeong, Han;Lee, Seung-U;Han, Won-Yong
    • Bulletin of the Korean Space Science Society
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    • 2009.10a
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    • pp.45.1-45.1
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    • 2009
  • 과학기술위성 3호의 주탑재체인 MIRIS (Multi-purpose InfraRed Imaging System)는 우주관측카메라 (Space Observation Camera, SOC)와 지구관측카메라 (Earth Observation Camera, EOC)가 독립적인 시스템으로 구성되어 있다. 지구관측카메라는 유효 구경 100 mm, F/5의 광학계로 3-5 마이크론 파장영역을 관측하며, 국내에서 개발된 적외선 검출기의 우주 인증 시험과 유사시 한반도 적외선 감시를 주요 목적으로 하고 있다. 고도 700km에서 지상을 볼 때 약 42m/pixel의 공간분해능을 나타낼 것으로 기대하고 있다. 지구관측카메라의 인증 모델(Qualification Model)은 냉동기를 제외한 모든 부품이 국내기술로 제작되었으며, 미러 본딩 및 릴레이 렌즈 조립 기술, 적외선 영상 검교정 기술 등 다양한 경험과 도전을 제공했다. 이 발표에서는 지구관측카메라 인증모델을 이용하여 수행한 주요 시험 과정을 소개한다. 국내 회사 (주)i3 system에서 제작된 적외선 검출기는 $320\times256$ HgCdTe array (평균 양자효율 80% 이상) 이며 77K에서 정상적으로 운영된다. Micro Stirling Cooler에 의해 듀어는 전원을 켠 후 5분 이내에 검출기 운영온도인 77K까지 내려간다. 적외선 광학계의 정렬, 시스템 MTF 측정, 흑체 측정 및 검교정 작업을 수행한 후 야외에서 다양한 경우에 대해 Field Test를 진행했다. 이 발표에서는 Field Test 과정과 이를 통해 얻은 결과를 발표하고, FM (Flight Model) 제작에 있어 수정해야 할 사항들을 제안해 본다.

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Crack Analysis using Constrained Delaunay Triangulation Crack Mesh Generation Method (Constrained Delaunay Triangulation 균열 요소 생성 기법을 이용한 균열 해석)

  • Yeounhee Kim;Yeonhi Kim;Jungsun Park
    • Journal of Aerospace System Engineering
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    • v.18 no.3
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    • pp.17-26
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    • 2024
  • Aircraft engines are exposed to high temperatures, high pressures, and stress caused by the rotation of the turbine shaft during flight. These loads can result in microcracks both on the inside and outside surfaces of the structure. Consequently, this can lead to structural defects and negatively impact the lifespan of the parts. To proactively prevent these defects, a finite element analysis is carried out to identify cracks. However, this process is time-consuming and requires significant effort due to the repetitive nature of crack modeling. This study aims to develop a crack modeling method based on the finite element model. To achieve this, the Constrained Delaunay Triangulation (CDT) technique is employed to triangulate the space while considering limitations on point connections. The effectiveness of this method is validated by comparing stress intensity factors for semi-elliptical cracks in plates and cylindrical vessels. This approach proves to be a valuable tool for crack analysis studies.

Two-Failure Gps Raim by Parity Space Approach (패러티 공간을 이용한 2개 GPS 파라미터 고장진단)

  • Yoo, Chang-Sun;Ahn, Iee-Ki;Lee,Sang-Jeong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.6
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    • pp.52-60
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    • 2003
  • In aviation navigation using GPS, requirements on availability and integrity must be absolutely satisfied. Current study on accomplishing this integrity includes RAIM(Receiver Autonomous Integrity Monitoring), monitoring integrity internaIly in GPS receiver itself. Parity space technique as one of RAIM techniques has shown the advantages in fault detection and isolation due to each use of its magnitude and direction under the assumption of one fault. ln case of multiple fault, as biases in errors interact decreasing the effect of multiple fault in parity space, the exact fault detection and identification(FDI) may be difficult to be conducted. This paper focuses on FDI study on two faults and explains why parity space techniques applied on single fault is not adequate to the application of multiple fault case and shows that extended parity space technique may improve the performance of RAIM on two faults.