• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.3
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• pp.228-239
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• 2016

CNUSAIL-1 is a 3U-sized cube satellite with $4m^2$ small solar sail which is currently being developed at the Chungnam National University. The primary purpose of the CNUSAIL-1 is successful sail deployment in LEO and its operation for investigating its effect on satellite orbit and attitude as well as performing de-orbiting using the sail membranes as drag sail at the final phase. The system design and mechanism of solar sail deployment is introduced, and optical and tensile tests are carried out for the material of membranes and booms for its safety and performance verification. The ground test is carried out to verify its performance for sail deployment and satellite through comparison between folding methods by determining its folding patterns, thickness of spiral spring and angular velocity measurement in a low-friction environment.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.109-118
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• 2018

Korea Aerospace Research Institute has developed a staged combustion cycle rocket (SCCR) engine with high specific impulse to send a 3-ton class satellite into geostationary orbit while conducting a Korean Space Launch Vehicle (KSLV) II project. The SCCR engine is different from the KSLV-II engine, which is an open cycle engine using a gas-generator. The SCCR engine with a closed cycle engine is composed of a pre-burner, a turbo pump, and a main combustor. The technology demonstration model (TDM0) was assembled and tested in the 7ton-class engine combustion test facility of Naro Space Center, and the combustion test was successfully conducted.

• Proceedings of the KSRS Conference
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• v.1
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• pp.159-162
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• 2006

This paper describes the ground system for COMS (Communication, Ocean, and Meteorological Satellite), the first Korean multi-purposed geostationary satellite, at MSC (Meteorological Satellite Center) in Korea. The overview of COMS MI (Meteorological Imager) will be introduced as well. KMA would implement mission planning for COMS MI operation and receive, process, interpret, disseminate, and archive MI data operationally for domestic and foreign user groups. Major missions of COMS MI are mitigation of natural hazard such as typhoon, dust storm, and heavy rain, and short-term warning of severe weather to protect human health and commerce. Moreover, research of climate variability and long-term changes will be supported. In accordance with those missions, the concept and design of COMPASS (COMS operation and meteorological products application service system), the ground system for COMS MI in MSC, have been setting up since 2004. Currently, COMPASS design is being progressed and will have finished the end of 2006. The development of COMPASS has three phases: first phase is development of fundamental COMPASS components in 2007, second phase is to integrate and test all of the COMPASS components in 2008, and the last phase is to operate COMPASS after COMS In-Orbit Tests in 2009.

• Archives of Plastic Surgery
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• v.45 no.3
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• pp.271-274
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• 2018

The decision of which surgical approach to use for the treatment of a multifocal craniofacial abscess is still a controversial matter. A failure to control disease progress in the craniofacial region can potentially put the patient's life at risk. Therefore, understanding the various ways to approach the craniofacial region helps surgeons to obtain satisfactory results in such cases. In this report, we describe a patient who visited the emergency department with a large swelling in his right cheek. A blood test and computed tomography revealed odontogenic maxillary sinusitis. The patient developed sepsis due to a progressive multifocal abscess. An abscess was seen in the temporal muscle, infratemporal fossa, and interorbital region. To control this multifocal abscess, we used the facial dismasking flap (FDF) approach. After debridement using the FDF approach, we succeeded in obtaining sufficient drainage of the abscess, and the patient recovered from sepsis. The advantages of the FDF approach are that it provides a wide surgical field, extending from the parietal region to the mid-facial region, and that it leaves no aesthetically displeasing scars on the face. The FDF approach may be one of the best options to approach multifocal abscesses in the craniofacial region.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.2
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• pp.193-199
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• 2013

This work investigates the orbital perturbations of the cubesats that lie on LEO due to Earth albedo. The motivation for this paper originated in the investigation of the orbital perturbations for closed- Earth pico-satellites due to the sunlight reflected by the Earth (the albedo). Having assumed that the Sun lies on the equator, the albedo irradiance is calculated using a numerical model in which irradiance depends on the geographical latitude, longitude and altitude of the satellite. However, in the present work the longitude dependency is disregarded. Albedo force and acceleration components are formulated using a detailed model in a geocentric equatorial system in which the Earth is an oblate spheroid. Lagrange planetary equations in its Gaussian form are used to analyze the orbital changes when $e{\neq}0$ and $i{\neq}0$. Based on the Earth's reflectivity data measured by NASA Total Ozone Mapping Spectrometer (TOMS project), the orbital perturbations are calculated for some cubesats. The outcome of the numerical test shows that the albedo force has a significant contribution on the orbital perturbations of the pico-satellite which can affect the satellite life time.

• Proceedings of the KSRS Conference
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• v.1
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• pp.372-375
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• 2006

The MSC is a high resolution multi-spectral camera system which is mounted on the KOMPSAT-II satellite. The electro-optic camera system has a refocusing mechanism which can be used in-orbit by ground commands. By adjusting locations of some elements in optics, the system can be focused precisely. The focus mechanism in MSC is implemented with stepper motor and potentiometer. By reading the value of the potentiometer, rough position of the motor can be understood. The exact location of the motor can not be acquired because the information from the potentiometer can not be so accurate. However, before and after certain events of the satellite, like a satellite launch, the direction of the movement or order of the magnitude of the movement can be understood. In this paper, the trend analysis of the focus motor position during the ground test phase is introduced. This result can be used as basic information for the focus calibration after launch. By studying the long term trend, deviation from the best focal point can be understood. The positions of the focus motors after launch are also compared.

• Journal of Astronomy and Space Sciences
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• v.38 no.2
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• pp.119-134
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• 2021

The data set collected during the night of the discovery of a minor body constitutes a too-short arc (TSA), resulting in failure of the differential correction procedure. This makes it necessary to recover the object during subsequent nights to gather more observations that will allow a preliminary orbit to be calculated. In this work, we present a recovery technique based on sampling the admissible region (AdRe) by the constrained Delaunay triangulation. We construct the AdRe in its topocentric and geocentric variants, using logarithmic and exponential metrics, for the following near-Earth-asteroids: (3122) Florence, (3200) Phaethon, 2003 GW, (1864) Daedalus, 2003 BH84 and 1977 QQ5; and the main-belt asteroids: (1738) Oosterhoff, (4690) Strasbourg, (555) Norma, 2006 SO375, 2003 GE55 and (32811) Apisaon. Using our sampling technique, we established the ephemeris region for these objects, using intervals of observation from 25 minutes up to 2 hours, with propagation times from 1 up to 47 days. All these objects were recoverable in a field of vision of 95' × 72', except for (3122) Florence and (3200) Phaethon, since they were observed during their closest approach to the Earth. In the case of 2006 SO375, we performed an additional test with only two observations separated by 2 minutes, achieving a recovery of up to 28 days after its discovery, which demonstrates the potential of our technique.

• Journal of Astronomy and Space Sciences
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• v.28 no.1
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• pp.63-70
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• 2011

The needs for satellite formation flying are gradually increasing to perform the advanced space missions in remote sensing and observation of the space or Earth. Formation flying in low Earth orbit can perform the scientific missions that cannot be realized with a single spacecraft. One of the various techniques of satellite formation flying is the determination of the precise baselines between the satellites within the formation, which has to be in company with the precision validation. In this paper, the baseline of Gravity Recovery and Climate Experiment (GRACE) A and B was determined with the real global positioning system (GPS) measurements of GRACE satellites. And baseline precision was validated with the batch and sequential processing methods using K/Ka-band ranging system (KBR) biased range measurements. Because the proposed sequential method validate the baseline precision, removing the KBR bias with the epoch difference instead of its estimation, the validating data (KBR biased range) are independent of the data validated (GPS-baseline) and this method can be applied to the real-time precision validation. The result of sequential precision validation was 1.5~3.0 mm which is similar to the batch precision validation.

• Journal of the Korean Solar Energy Society
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• v.24 no.2
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• pp.51-62
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• 2004

Architects may evaluate building models to see how a building will shadow itself and its neighbors at various times. A heliodon, a tilt-table which is a machine that imitates the rotation and orbit of the Earth, helps architects wanting to analyze patterns of shadow patch, passive solar heating options, site solar panels, or control solar heat gain. The heliodon swivels in three directions for setting latitude, season, and time of day. Using the device, an architect first clamps a model to the tabletop, then turns the table to the coordinates of interest. Usually, the winter and summer solstices receive strong attention, for they represent extreme cases, A more recent installation at a university adds to its heliodon a set of lamps to recreate the illumination level and more accurate patterns of shadow patch. The table holds the building model at various angles to a spotlight, which mounts in the pole. The set of scale model measurement describes the validity of various electric lamps as an artificial sun to approximate the sun's parallel rays, helping designers to distinguish between illuminated areas in and around a building and those regions falling in the shadows.

• Aerospace Engineering and Technology
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• v.2 no.1
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• pp.80-88
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• 2003

The present analysis quantifies the particulate contamination of KOMPSAT-2 satellite until in orbit life. Assumptions are defined about integration and test conditions and durations, then a budget is drawn. As KOMPSAT-2 activities are carried out in good cleanliness conditions, the particulate contamination budgets for satellite and instrument surfaces at BOL is fair. To summarise, in the baseline launch conditions (class 10,000) the contribution of satellite AIT and launch activities adds 500 PPM to MSC and STA apertures (telescope mirrors ; front lens ; baffle), 20,000 PPM to MSC and STA outer surfaces, 14 000 PPM to plate-form horizontal surfaces, 1400 PPM to plate-form vertical surfaces, 1000 PPM to plate-form radiators and less than 300 PPM to solar arra.