• International Journal of Control, Automation, and Systems
• /
• v.4 no.3
• /
• pp.333-343
• /
• 2006

In this paper, the baseline-length information is directly modeled as a measurement for the Wald test, which speeds up the resolution convergence of the integer ambiguity of GPS carrier phase measurements. The convergent speed improvement is demonstrated using numerical simulation and real experiments. It is also shown that the integer ambiguities can be resolved using only four actual satellite measurements with very reasonable convergence speed, if the baseline-length information is used just like one additional observable satellite measurement. Finally, it is shown that the improvement of convergence speed of the Wald test is due to the increase of the probability ratio with the use of the baseline-length constraint.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.242-245
• /
• 2006

This paper is an assessment on the dynamic test results of optical bench for LEO satellite. According to the design requirements, optical bench was designed and manufactured. Dynamic test was performed to verify stability of optical bench. Low level random vibration test, sine burst test and sine vibration test are carried out to identify dynamic characteristics and to verify static strength and safety under quasi-static load conditions. From the result it can be stated that the optical bench is well qualified under the launch environmental conditions.

• International Journal of Aeronautical and Space Sciences
• /
• v.4 no.2
• /
• pp.69-78
• /
• 2003

In this paper, we develop the so-called functional test model for magnetic bearing wheels. The functional test model developed in this paper is a kind of electromagnetic suspension systems and has three degree of freedom, which consists of one axial suspension from gravity and the other two axes gimbaling capability to small angle, and does not include the motor. For the control of the functional test model, we derive the optimal electromagnetic forces based on the least squares method, and use the proportional-integral derivative controller. Then, we develop a hardware setup, which mainly consists of the digital signal processor and the 12-bit analog-to-digital and digital-to-analog converters, and show the experimental results.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.44 no.2
• /
• pp.156-164
• /
• 2016

Qualification model(QM) of main payloads including concentrating photovoltaic system using fresnel lens, heating wire cutting type shockless holding and release mechanism, and MEMS-based solid propellant thruster have been developed for the STEP Cube Lab.(Cube Laboratory for Space Technology Experimental Project), which is a pico-class satellite for verification of core space technologies. In this study, we have verified structural safety and functionality of the developed payloads under a qualification temperature range through the QM thermal vacuum test. Additionally, a reliability of thermal model of the payloads has been confirmed by performing a thermal correlation based on the thermal balance test results.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.1107-1108
• /
• 2011

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.197-202
• /
• 2006

The low-altitude earth observation satellite is generally equipped with high performance camera as a main payload which is vulnerable to vibration environment. During the launch process of a satellite, the combustion and jet noise of launch vehicle produce severe acoustic environment and the acoustic loads induced may damage the critical equipments of the satellite including the camera. Therefore to predict and simulate the effect of the acoustic environment which the satellite has to sustain at the lift-off event is very important process to support the load-resistive design and test-qualification of components. Statistical Energy Analysis(SEA) has been widely used to estimate the vibro-acoustic responses of the structures and gives statistical but reliable results in the higher frequency region with less modeling efforts and calculation time than the standard FEA. In this study, SEA technique has been applied to a 3-Dimensional model of a low-altitude earth observation satellite to predict the acceleration responses on the structural components induced by the high level acoustic field in the launch vehicle fairing. In addition, the expected response on each critical component panel was calculated by the classical method in consideration of the mass loading and imposed sound pressure level, and then compared with SEA results.

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.413-416
• /
• 2004

The tracking antenna system must be always pointed to a satellite for data link among moving vehicles. Especially, for an antenna mounted on a moving vehicle, it needs the stabilized the antenna system. So, software and hardware, signal processing of motion detection sensors, real-time processing of vehicle dynamics, trajectory estimation of satellite, antenna servo mechanism, and tracking algorithm, are unified in the antenna system. The purpose of this paper is to design the embedded tracking antenna control system for satellite communication. The embedded OS(Operating System) based stabilization and tracking algorithm was implemented. The performance of the designed embedded control system was verified by the real satellite communication test.

• Journal of Aerospace System Engineering
• /
• v.15 no.5
• /
• pp.113-128
• /
• 2021

In this paper, we present a simple ground receiving station as an educational method for a satellite system. Our system is produced similarly to the existing fixed ground station in terms of function by using satellite communication technology and related software commonly used in the amateur radio field. In addition, we conducted operation test to receive signals from operating satellites and confirmed the possibility of using them as a way to educate satellite systems, such as understanding ground station systems through satellite reception experience and satellite state information acquisition, and further designing satellite systems.

• Journal of Astronomy and Space Sciences
• /
• v.30 no.4
• /
• pp.279-290
• /
• 2013

Due to the continuous space development by mankind, the number of space objects including space debris in orbits around the Earth has increased, and accordingly, difficulties of space development and activities are expected in the near future. In this study, among the stages for space debris removal, the implementation of a vision-based approach technique for approaching space debris from a far-range rendezvous state to a proximity state, and the ground test performance results were described. For the vision-based object tracking, the CAM-shift algorithm with high speed and strong performance, and the Kalman filter were combined and utilized. For measuring the distance to a tracking object, a stereo camera was used. For the construction of a low-cost space environment simulation test bed, a sun simulator was used, and in the case of the platform for approaching, a two-dimensional mobile robot was used. The tracking status was examined while changing the position of the sun simulator, and the results indicated that the CAM-shift showed a tracking rate of about 87% and the relative distance could be measured down to 0.9 m. In addition, considerations for future space environment simulation tests were proposed.

• Aerospace Engineering and Technology
• /
• v.12 no.2
• /
• pp.14-23
• /
• 2013

Fault management design of the satellite describes preparations for failures which can occur during operational phase. Fault management design contains detection and isolation function of anomaly, and also it contains function to maintain the satellite in safe condition until the ground station finds out a cause of failure and takes a countermeasure. Unlike normal operation, safing operation is automatically performed by Power Control and Distribution Unit and Integrated Bus Management Unit which loads Flight Software without intervention of ground station. Since fault management operation is automatical, fault management logic and functionality of relevant hardware should be thoroughly checked during ground test phase, and error which is similar to actual should be carefully applied without damage. Verification test for fault management design is conducted for various subsystems of satellite. In this paper, we show the design process of fault management design verification test for Electrical Power Subsystem and Attitude and Orbit Control Subsystem of Low Earth Orbit satellite flight model and the test results.