• Bulletin of the Korean Space Science Society
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• 1997.04a
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• pp.33.2-33
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• 1997

No Abstract.See Full-text

• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.57-65
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• 2005

Due to the future of a large size satellite like Geo-stationary orbit satellite, KARI has progressed the construction of Large Thermal Vacuum Chamber(LTVC) with Φ8mXL10m, which simulates the orbit environment at space. The space environment can be characterized as very harsh conditions. Once the spacecraft is launched and enters its orbit, the satellite is exposed to this space environment. The continuous exposure to such space environment could cause malfunction of major parts of the spacecraft, which could lead to the failure of the entire mission. Due to the fact that space environment is completely different from that of the ground, the satellite that functioned normally on the ground could show some unexpected malfunction in space environment. For this reason, the performance of the spacecraft must be confirmed under the simulated conditions of the space environment. This document includes LTVC control logic, Interlock by which the LTVC can be controlled more safely and efficiently.

• Journal of Satellite, Information and Communications
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• v.3 no.1
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• pp.29-34
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• 2008

After spacecraft is separated from the launch vehicle, first of all spacecraft deploy the solar array. Solar array deployment is one of the key factors deciding the success of the spacecraft mission. Therefore, It is necessary to predict the solar array deployment motion and check the safety through calculating the load on the tape hinges of solar array using the deployment analysis in the initial design phase. In this paper, solar array deployment analysis is performed by multi-body dynamics simulation program. From the analysis results, assessment on the safety also is carried out. In addition, hinge characteristic test is fulfilled to find out hinge characteristic, and is applied to the deployment analysis.

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.1-7
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• 2010

For many years the development and verification of on-board flight software have been essentially performed on STB (Software Test Bed) environments which consist of real hardware in KARI. During development of on-board flight software on STB, we experienced many difficulties such as the late delivery of target hardware and limitation to access STB simultaneously by multiple developers. And it takes too much time and cost to build up multiple STBs. In order to successfully resolve this kind of problems, the software-based spacecraft simulator has been developed. The simulator emulates the on-board computer, I/O modules and power controller units and it supports the debugging and test facilities to software engineers for developing flight software. Also the flight software can be loaded without any modification and can be executed as pseudo real-time. This paper presents the architecture and design of software-based spacecraft simulator, and flight software development and verification under this environment.

• Journal of Aerospace System Engineering
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• v.11 no.2
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• pp.30-34
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• 2017

This paper is concerned with product assurance for the secondary payload, which is used for technology and science research, in the satellite system, which consists primarily of the spacecraft and the primary payload (a high-resolution optical camera). The Korean satellite development program has successfully insured the safety of the spacecraft and primary payload. However, given the limits of budget and schedule, it is very important to establish adequate product assurance for the secondary payload, which has a lower priority than the spacecraft or primary payload. This paper studies the concept of product assurance for the secondary payload of technological and scientific equipment.

• Journal of Satellite, Information and Communications
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• v.9 no.4
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• pp.97-103
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• 2014

In order to verify normal operation of satellite OBC(On Board Computer), it is essential that processor monitoring and debugging. So we are using the GRMON of Aeroflex Gaisler. It provides a lot of features for debugging of LEON processor but we can't use that features on the NGSCB(Next Generation Spacecraft Computer Board) except a few things. So the cost-effectiveness is very low. And for hardware fault injection, we are using a method of modify satellite flight software, because we can't modify GRMON. This method can not guarantee normal operation of the satellite flight software. So in this paper we were developed the processor monitoring and fault injection tool for NGSCB.

• Journal of The Korean Astronomical Society
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• v.56 no.2
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• pp.293-299
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• 2023

The Wide-Angle Polarimetric Camera (PolCam) is installed on the Korea's lunar orbiter, Danuri, which launched on August 5, 2022. The mission objectives of PolCam are to construct photometric maps at a wavelength of 336 nm and polarization maps at 461 and 748 nm, with a phase angle range of 0°-135° and a spatial resolution of less than 100 m. PolCam is an imager using the push-broom method and has two cameras, Cam 1 and Cam 2, with a viewing angle of 45° to the right and left of the spacecraft's direction of orbit. We conducted performance tests in a laboratory setting before installing PolCam's flight model on the spacecraft. We analyzed the CCD's dark current, flat-field frame, spot size, and light flux. The dark current was obtained during thermal / vacuum test with various temperatures and the flat-field frame data was also obtained with an integrating sphere and tungsten light bulb. We describe the calibration method and results in this study.

• Aerospace Engineering and Technology
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• v.6 no.1
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• pp.74-82
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• 2007

The M-Method that measures the speed of actuator with counting the number of Reaction wheel Tacho Pulse has the many advantages such that a realization is simple and measuring time is uniform, but it also has the disadvantage that measuring speed becomes worse as the wheel speed goes lower. On the contrary, the T-Method that measures the time duration between the pulses is more accurate at lower-speed and its time delay is smaller than M-Method, but its realization is more difficult than M-Method because measuring time is varying with wheel speed variation. Thought M/T Method mixing M-Method with T-Method is widely used in order to measure the speed in the motor industrial area, one of two methods has been used in the spacecraft design area. Therefore, we try to apply both methods together to measuring the speed of Reaction Wheel, the core actuator for low earth orbit satellite. This paper provides the Reaction Wheel simulation board located in the Spacecraft Dynamic Simulator, ground support test set.

• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.103-107
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• 2005

There is an X-band transmission system in KOMPSAT-2 in order to downlink the acquired image data in high speed. KOMPSAT-2 employs a steerable high gain X-band antenna for that purpose. During the ground test, the X-band RF radiation is so strong that it has to be controlled for safety, while spacecraft needs to keep flight configuration. Also in a launch site of which all test facilities are the subjects of strict radiation control, the antenna system should be tested again without any change in the configuration. To limit the actual radiation of RF power, an antenna hat was manufactured and thoroughly tested to demonstrate the spacecraft safety when using it.

• Aerospace Engineering and Technology
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• v.13 no.1
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• pp.120-128
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• 2014

Adventure of human race for space exploration is toward outer region of solar system. Recently the main targets of space explorations are becoming mainly the Mars, Venus and asteroids instead of the Moon which was the popular place human wants to explore. There are several technical challenges as spacecraft goes far and far away from the Earth, and among them communication protocol is one of the most challenging problems. In this paper, several international technical trends regarding deep space communication protocol technologies in an aspect of software implementation is presented. It is expected that these references are helpful for the development of the lunar orbiter pathfinder which is planned to be launched in 2017.