• Journal of Advanced Navigation Technology
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• v.16 no.6
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• pp.900-909
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• 2012

Low Earth orbit satellites with satellite navigation receiver use onboard navigation filters for filtering measurement signals and for orbit prediction under signal loss. Precision satellite dynamic models, core of the navigation filter, are studied and a computation program is developed. Gravity acceleration, precision coordinate transform, third-body gravity, atmospheric drag, and solar radiation pressure models are combined into an orbit prediction algorithm, and a proven precision orbit determination software is used to validate the program. Orbit prediction accuracy is analyzed with simulated and flight orbit data. The program meets an accuracy level for onboard real-time navigation filter.

• Aerospace Engineering and Technology
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• v.13 no.2
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• pp.73-79
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• 2014

During developing cubesat flight software, Communication test between cubesat and ground station is needed. For this, we have constructed indoor ground station without outdoor antenna for decreasing total cost and time. In this time, if output power of ground station is high, it will affect for cubesat transceiver to be fail. For solving this problem, ground station must be designed for output power of it to be lower than input power of cubesat satellite, and it must be verified. In this paper, first, we describe cubesat indoor ground station using UHF and VHF. Second, we describe output power decreasing test for indoor operation of ground station by attaching attenuators in the end of the output connector.

• Annual Conference of KIPS
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• 2006.05a
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• pp.1171-1174
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• 2006

고신뢰도가 요구되는 위성용 탑재소프트웨어를 개발하기 위해서는 소프트웨어 처리기반으로 고성능의 탑재컴퓨터가 요구된다. 향후 개발될 위성을 위한 고성능 탑재컴퓨터로는 유럽에서 개발되어 사용되고 있는 MCM-ERC32를 채용할 예정이다. ESA(European Space Agency)의 지원 하에 개발된 MCM-ERC32는 32-비트의 ERC32SC 프로세서, 부가적인 기능을 제공하는 ASIC인 VASI(Very Advanced Sparc Interface), 그리고 메모리(SRAM, DRAM, EEPROM, etc.)로 구성되어 있다. MCM-ERC32에는 ERC32 프로세서에서 제공되는 2개의 UART(A/B)와 VASI에서 제공하는 4개의 UART(0/1/2/3), 총 6개의 시리얼 인터페이스가 있다. ERC32에서 제공하는 시리얼 인터페이스는 8-비트 모드만 지원되며 전송속도에도 제한이 있기 때문에 탑재소프트웨어의 업로드 및 디버깅용으로 활용될 예정이며, 탑재체 간의 인터페이스로는 VASI에서 제공하는 시리얼 인터페이스를 사용할 예정이다. VASI에서 제공하는 UART는 MCM-ERC32에 적합하도록 개발되어 일반적인 임베디드 시스템의 시리얼 인터페이스와는 구별되는 송수신 방법 및 기능을 제공한다. 본 논문에서는 이러한 VASI UART의 구성 및 특징과 기능들에 대하여 설명하도록 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.511-513
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• 2004

위성의 부분체 또는 탑재컴퓨터 및 탑재소프트웨어에 대한 검증시험을 수행하기 위해서는 위성개발에 사용하며 그 기능이 검증된 상용프로그램을 사용하는 것이 일반적이다. 그러나 위성 영령의 전송 및 텔레메트리 데이터의 전송과 분석을 위한 프로그램은 위성에 사용되는 종류 및 포맷에 따라 다양한 형태로 수정되어야 하기 때문에 자체 제작한 프로그램을 사용하게 된다. 99년에 발사되어 성공적으로 임무를 수행하고 있는 다목적실용위성 1호 및 현재 개발이 진행 중인 다목적실용위성 2호의 개발과정에서는 LEX와 YACC이라는 구문분석기를 이용한 VTSP(Verification Test Script Parser) 프로그램이 탑재소프트웨어의 검증시험에 사용되었다. VT5P는 실시간 데이터 전송 및 분석이 가능하지만 UNIX 환경에서만 실행되므로 윈도우 환경에서 작업하던 일반 사용자들에게는 익숙하지 않은 시험환경을 제공하여 텍스트 기반의 작업이 필요하므로 시험 수행에 여러 어려움들이 발생한다. 이러한 단점들을 보완하기 위하여 윈도우 기반의 검증시험 프로그램인 SATS(Spacecraft Automatic Test Script)를 개발하였다. 본 논문에서는 대부분의 사용자들에게 익숙한 윈도우 환경을 제공하며 이더넷을 통하여 장소에 상관없이 다중의 개발자가 시험을 수행할 수 있는 SATS의 개발현황과 수행환경에 대하며 소개한다.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.1
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• pp.44-53
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• 2014

A lightning strike to the aircraft seriously affects the aircraft and its components in various ways. As one of the most critical threats to the flight safety of an aircraft, fuel vapour ignition by lightning can occur through various means, notably through hot spot formation on the fuel tank skins. In this study, a coupled thermal-electrical approach using the commercial software ABAQUS is used to study the effects of a lightning strike on aircraft fuel tanks. This approach assumes that the electrical conductivity of a material depends on temperature, and that a temperature rise in a material due to Joule heat generation depends on electrical current. The inter-dependence of thermal and electrical properties-the thermal-electrical coupling-is analyzed by a coupled thermal-electrical analysis module. The analysis elucidates the effects of different material properties and thicknesses of tank skins and identifies the worst case of lightning zones.

• Journal of Microbiology and Biotechnology
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• v.16 no.1
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• pp.25-31
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• 2006

Changes of CP4 5-enolpyruvylshikimate-3-phosphate synthase (CP4 EPSPS) in the glyphosate-tolerant Roundup Ready soybean were examined using purified CP4 EPSPS produced in cloned Escherichia coli as a control. CP4 EPSPS in genetically modified soybean was detected by twodimensional gel electrophoresis (2-DE) and identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and electrospray ionization tandem mass spectrometry (ESI-MS/MS) with databases. CP4 EPSPS in soybean products was resolved on 2-DE by first isoelectric focusing (IEF) based on its characteristic pI of 5.1, followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) based on its molecular mass of 47.5 kDa. We quantified various percentages of soybean CP4 EPSPS. The quantitative analysis was performed using a 2D software program on artificial gels with spots varying in Gaussian volumes. These results suggested that 2-DE image analysis could be used for quantitative detection of GM soybean, unlike Western blotting.

• Wind and Structures
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• v.31 no.1
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• pp.15-20
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• 2020

The aircraft industry supports aviation by building aircraft and manufacturing aircraft parts for their maintenance. Fuel economization is one of the biggest concerns in the aircraft industry. The reduction in specific fuel consumption of aircraft can be achieved by a variety of means, simplest and more effective is the one to impose minor modifications in the aircraft main wing or the parts which are exposed to the air flow. This method can lead to a reduction in aerodynamic resistance offered by the air and have a smoother flight. The main objective of this study is to propose geometric design modifications on an existing aircraft wing which acts as a vortex generator and it can reduce the drag and increase lift to drag ratio, leading to lower fuel consumption. The NACA 2412 aircraft wing is modified and designed. Rigorous flow analysis is carried out using computational fluid dynamics based software Ansys Fluent. Results show that saw tooth modification to the main wing shows the best aerodynamic efficiency as compared to other modifications.

• Journal of Astronomy and Space Sciences
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• v.27 no.4
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• pp.377-382
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• 2010

In lunar explorer development program, computer simulator is necessary to provide virtual environments that vehicle confronts in lunar transfer, orbit, and landing missions, and to analyze dynamic behavior of the spacecraft under these environments. Objective of simulation differs depending on its application in spacecraft development cycle. Scope of use cases considered in this paper includes simulation of software based, processor and/or hardware in the loop, and support of ground-based flight test of developed vehicle. These use cases represent early phase in development cycle but reusability of modeling results in the next design phase is considered in defining requirements. A simulator architecture in which simulator platform is located in the middle and modules for modeling, analyzing, and three dimensional visualizing are connected to that platform is suggested. Baseline concepts and requirements for simulator development are described. Result of trade study for selecting simulation platform and approaches of defining other simulator components are summarized. Finally, characters of lunar elevation map data which is necessary for lunar terrain generation is described.

• Aerospace Engineering and Technology
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• v.2 no.1
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• pp.73-79
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• 2003

Usual satellite design adopts hardware Error Detection and Correction (EDAC) circuitary for memory elements to endure proper operation in space radiation environment and periodic read-back(scrubbing) scheme to remove errors occurred and to prevent further accumulation of errors, in parallel, But lack of detail radiation test data upset rates of KOMPSAT-2 mass storage was estimated very worse compared to that of KOMPSAT-1, which was evaluated from very precise radiation test. Although upset rates were evaluated enough low to accommodate by KOMPSAT-2 Flight Software, hardware scrubbing scheme is studied to shorten scrubbing time as well. This paper describes hardware scrubbing architecture having minimum 1.88 minutes scrubbing interval over 1 Gbits memory.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.66.3-66.3
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• 2017

Korea Astronomy and Space Science Institute (KASI) is developing a coronagraph in collaboration with National Aeronautics and Space Administration (NASA) which will be installed on the International Space Station (ISS). The coronagraph can measure speed and temperature by using four filters approximately 400 nm and polarization filter in three different angles, differently with older coronagraphs. For the successful mission, it has development and experiment progress in three phases; total solar eclipse experiment in 2017, balloon experiment in 2019, and the ISS installation in 2021. As a first experiment, we developed a coronagraph without an occulter named with Diagnostic Coronagraph Experiment (DICE) for experiment for filter system and imaging sensor. We designed optics with a field of view from 2.5 to 15 solar radii. It has four filters approximately 400 nm and polarizer to measure speed and velocity of the solar corona. For the selection of filter or polarization angle, it has two mechanism parts; filter wheel assembly and a polarizer wheel assembly. Especially we used Core Flight System (CFS) platform which was developed by NASA, when we develop the coronagraph operation software. It provides us stability, reusability, and compatibility.