• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.212-215
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• 2004

GOES-9 has been operated with the status of the Image Motion Compensation(IMC) off since last October. As the IMC function turned off, the sub-satellite point(SSP) of GVAR data was changed with the effect of the satellite motions. This makes the image registration, to maintain pixels within an image and between successive images to their earth-referenced information, not to be possible any more. In the paper, we introduce the method to accomplish image registration and the result of the SSP observation with the status of IMC off.

• 한국소음진동공학회논문집
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• 제21권8호
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• pp.691-697
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• 2011

The purpose of this study is to analyze nonlinear dynamics of a tethered satellite. The coupled non-linear equations of motion are derived by using the extended Hamilton's principle with the polar coordinate system. In order to analyze the response of tethered satellite, time responses are computed by the Newmark's time integration method. We also investigate the dynamic behavior of the system and the effects of length of tether, tip mass and conveyed fluid through the tether with time variation.

• 한국소음진동공학회논문집
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• 제21권5호
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• pp.416-421
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• 2011

The purpose of this study is to analyze nonlinear dynamics of a tethered satellite. The nonlinear equations of motion are derived by using Lagrange's equations with the polar coordinate system. In order to analyze the response of tethered satellite, time responses are computed by the Newmark's time integration method. This paper claims that the dynamic behavior of the system is changed by the effect of length of tether, mass ratio of satellites.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권11호
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• pp.5497-5512
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• 2016

An improved optimal weights based on parallel interference cancellation algorithm has been proposed to cancel for interference induced by multi-user access satellite to ground uplink system. Due to differences in elevation relative motion between the user and the satellite, as well as access between users, resulting in multi-user access interference (Multi-user Access Interference, MUI), which significantly degrade system performance when multi-user access. By steepest gradient method, it obtained based on the MMSE criterion, parallel interference cancellation adjust optimal weights to obtain the maximum SINR. Compared to traditional parallel interference cancellation (Parallel Interference Cancellation, PIC) algorithm or serial interference cancellation ( Successive interference Cancellation, SIC), the accuracy of which is not high and too many complex iterations, we establish the multi-user access to the satellite to ground up link system to demonstrate that the improved WPIC algorithm could be provided with high accuracy and relatively low number of iterations.

• ETRI Journal
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• 제16권2호
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• pp.27-41
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• 1994

A new mathematical model to predict the beam pointing instability of a nonconservative two-body satellite system in spinning injection mode has been developed by using Newton-Euler and projection methods. Since the on-axis and null axis of the omni antenna with toroidal pattern beam form a right angle, wobbling of the antenna on-axis is measured by determining the Euler angles which represent the orientation of the satellite's spin axis. Because of the complexity of the system which is a time varying, nonstationary, nonlinear dynamical system, a numerical method is used for the analysis. Computer simulation results present the effects of the mass distribution and internal mass motion on the antenna beam pointing.

• 천문학회보
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• 제33권2호
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• pp.48.1-48.1
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• 2008

• Transactions on Control, Automation and Systems Engineering
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• 제4권2호
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• pp.169-175
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• 2002

A sliding mode control of spacecraft attitude tracking with actuator, especially reaction wheel, is presented. The sliding mode controller is derived based on quaternion parameterization for the kinematic equations of motion. The reaction wheel dynamic equations represented by wheel input voltage are presented. The input voltage to wheel is calculated from the sliding mode controller and reaction wheel dynamics. The global asymptotic stability is shown using a Lyapunov analysis. In addition the robustness analysis is performed for nonlinear system with parameter variations and disturbances. It is shown that the controller ensures control objectives for the spacecraft with reaction wheels.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.373.2-373
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• 2002

This research is concerned with dynamic modeling of satellite with deployable solar arrays equipped with strain energy hinges (SEH). It is found from experiments that the SEH has nonlinear dynamic characteristics and complex buckling behavior, which is difficult to explain theoretically In this paper, we use an equivalent one dimensional nonlinear torsional spring for the SEH. Lagrangian equations of motion are used for the derivations.

• Journal of Ship and Ocean Technology
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• 제7권4호
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• pp.32-40
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• 2003

Numerical simulation code is developed to study the formation of liquid drops from a nozzle into another quiescent liquid. The Navier-Stokes equations for two immiscible, incompressible, Newtonian fluids are solved on a fixed, staggered grid of cylindrical axisymmetric coordinates. Interfacial motion is captured using a Front-Tracking Method. The time variation of interfacial shape simulated by the code is in excellent agreement with experiments. Simulation results show that the viscosity ratio affects the size of the satellite drops.

• 한국정보통신학회논문지
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• 제7권6호
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• pp.1146-1152
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• 2003

선박이나 자동차 등의 이동체에서, 이동중에 위성 TV를 볼 수 있도록 하기 위해서는 이동체용 TV 위성 수신안테나 개발이 요구된다. 현대사회에서 TV가 갖고 있는 정보는 정보 수집을 위한 매체로서의 기능뿐만 아니라, 이미 우리생활의 일부가 되어 있다. 특히 한국에서는 무궁화위성을 이용한 다채널위성방송이 시작되어 화질과 음질에서 뛰어난 프로그램을 제공하고 있어 위성을 이용한 TV수신은 이미 대중화되기 시작하였다. 본 연구에서는 수평추적은 자이로센서를 이용한 방위정보와 수신신호 강도를 측정 비교하는 하이브리드형 추적알고리즘을 사용하였고, 수직방향추적은 짐발(무게추)을 이용한 선박용 위성 TV 수신안테나 시스템을 개발하였다. 본 연구의 결과로서 소형으로서 경제적인 가격의 27dBi 평판배열안테나와 선박의 움직임이 롤링, 피칭$\pm$30도까지도 추적이 가능한 추적 알고리즘을 개발하였다.