• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.428-431
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• 2008

Korea Aerospace Research Institute(KARI) is achieving the Korea Space Launch Vehicle(KSLV) program according to National Space Technology Development Program. KSLV-I will be composed to liquid propellant(first stage) and solid propellant(second stage) propulsion system. The propulsion system of KSLV-I second stage is solid kick motor with high expansion ratio and its starting altitude is 300km high. In order to verify the performance of upper stage propulsion system designed to operate in the upper atmosphere, test facility which can simulate high altitude is needed. High Altitude Simulation Test Facility is composed to Thrust Measurement System, Control & Measurement system, Diffuser, SKID for cooling water supply to diffuser, CCTV, fire protection system and so on. This paper introduces TMS adapted to High Altitude Simulation Test for KSLV-I Kick Motor Development and results of hot firing test for its performance verification.

• KIEAE Journal
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• v.15 no.1
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• pp.83-88
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• 2015

This study aims to develope the light-weight PV blinds with windows and to investigate the shading analysis by the control conditions. For the study, the polycarbonate characteristics and coating methods are analyzed and the PV blind design for a small office is suggested. Also, the mock-up model of a suggesting system was made. The field tests were controled based on a solar altitude under clear sky conditions. As results, it is necessary to use a polycarbonate instead of a tempered glass for a light-weight PV. The shading effects of blind systems are high in slat angle $30^{\circ}$ and low in $0^{\circ}$. Also, the shading ratio is more affected by solar latitude than solar altitude. The shading change rate is relevantly constant on the solar altitude.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.403-406
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• 2009

This research is based on the altitude temperature, pressure and humidity, as defined by MIL-HDBK-310 standard and modifies this conditions to conform to the new standard MIL-STD-810F and test procedure given in AIAA-2466 from this fundamental guideline optimal design and sizing of test section, inlet, exhauster duct, temperature and humidity control was performed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.10
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• pp.1017-1025
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• 2008

The air data system(ADS) was developed for unmanned aerial vehicle(UAV) in this paper. Generally, the ADS helps flight control computer(FCC) to control the UAV above the stall speed and to hold the given altitude. The accurate measurement of airspeed and altitude of UAV is important because it indicates a flight performance and assures a safe flight. The ADS consists of MEMS pressure sensors, a lowpass filter, a micro controller unit and a pitot-tube. The ADS errors were reduced by pressure and temperature compensation of MEMS sensors. Finally, the altitude and airspeed data of the ADS was compared with GPS data in the flight test.

• Journal of Information Technology Applications and Management
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• v.30 no.6
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• pp.81-90
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• 2023

In aviation, with the rapid transformation of the mobility industry, UAMs are emerging to operate green low-altitude airspace in urban environments. In order for UAM aircraft to fly safely transporting passengers and cargo in low-altitude urban airspace, a traffic control system that supports the safe operation of the aircraft is essential. In particular, traffic control systems that reflect the characteristics of the flight environment, such as operating at low altitude in urban environments for a short period of time, are required. In this study, we define the definition of UATM and its main services that perform traffic control for the safe operation of UAMs. In addition, we analyzed the development trends of UATM systems based on domestic and overseas cases. Based on these analyses, we present the results of the concept design of the UATM system. After analyzing UATM development cases, we found that there is no commercialized UATM system, but overseas development is focused on systems that can integrate ATM and UTM. And we identified key stakeholders and interface data, and performed UATM system architecture and functional design based on the identified data. Finally, as a necessary element for the future development of UATM systems, we propose the establishment and advancement of UAM traffic flow management systems, the establishment of integrated control systems, and the development of interface with aircraft operation systems in preparation for the unmanned UAM aircraft.

• Journal of Astronomy and Space Sciences
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• v.23 no.2
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• pp.127-134
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• 2006

Variation of the Local Time of Ascending Node (LTAN) has been analysed according to initial inclinations when the altitude of Sun-synchronous satellite is continuously decreased due to the atmospheric drag. Orbit predictions of 3 years have been performed with the satellite of 500 km altitude when the initial LTAN were set to 06:00, 09:00, 12:00, 15:00, and 18:00. Different profiles of the inclination and LTAN have been obtained according to the satellite altitude decay and initial LTAN value. Using the profiles of the inclination and LTAN, initial orbital elements can be derived for minimizing the LTAN variations during the mission life time of the sun-synchronous satellite without any on-board thrusters for orbit maneuvers.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.6
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• pp.68-75
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• 2011

A vehicle fuel economy is very important issue in view of fuel cost and environmental regulation. It has been improved according to the performance improvement of the vehicle engine, power train and many components. It was evaluated at given mode (LA-4, FTP-75, etc) on an engine dynamometer or computer simulation program. In this paper, the fuel economy improvement cruise control algorithms as controling a vehicle velocity by road load calculated and predicted in a real expressway with gradient was studied. Firstly, the altitude and distance data which was measured with GPS sensor was already installed in the ECU of a vehicle. Then the vehicle equipped with GPS receiver is driven the same expressway. The ECU calculates the gradient angle and the in-/decreasing velocity using the gradient angle by comparing the current received distance and altitude data from GPS with the saved data ahead of the vehicle. Therefore the ECU can calculate and predict the vehicle velocity considering tolerance velocity of next position with running. Then the ECU controls the vehicle velocity to meet this predicted velocity in all section. Three cruise control algorithms with the different velocity profiles for the improvement of fuel economy are proposed and compared with the computer simulation results that the vehicle runs on Youngdong expressway. The proposed CVELCONT2 and CVELCONT3 algorithms were improved 3.7% and 4.8% of fuel economy compared with CONSTVEL which is steady cruising algorithm. These two algorithms are recommended as the Eco-cruise drive methodologies in this paper.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.36 no.4
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• pp.223-233
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• 2018

In this study was classified the cadastral control points and parcel boundary points into 40m, 100m by flight altitude of UAV (Unmanned Aerial Vehicle) which compared the coordinates extracted from the orthophoto with the parcel boundary point coordinates by GNSS (Global Navigation Satellite System) ground survey. As a results of this study, first, in the spatial resolution analysis that the average error of the orthoimage by flight altitude were 0.024m at 40m, and 0.034m at 100m which were higher 40m than 100m for spatial resolution of orthophotos and position accuracy. Second, in order to analyze the accuracy of image recognition by airmark of flight altitude that was divided into three cases of nothing, green, and red of RMSE (Root Mean Square Error) were X=0.039m, Y=0.019m and Z=0.055m, the highest accuracy. Third, the result of the comparison between orthophotos and field survey results that showed the total RMSE error of the cadastral control points were X=0.029m, Y=0.028m, H=0.051m, and the parcel boundary points were X=0.041m, Y=0.030m. In conclusion, based on the results of this study, it is expected that if the average error of flight altitude is limited to less than 0.05m in the legal regulations related to orthophotos for cadastral surveying, it will be an economical and efficient method for cadastral survey as well as spatial information acquisition.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.148.4-148
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• 2001

This paper shows an autopilot design example with simulation results for a medium range surface-to-air missile used to intercept fast maneuver targets. The missile is assumed to use both aerodynamic fins and side thrusters to achieve fast time response. The steady-state maneuver capability of the missile is assumed to be enough at high altitude to engage usual maneuvering targets. Side thruster is used to get an extremely rapid acceleration response at high altitude where the missile´s aerodynamic control effectiveness is weak. The strategy of control design is firstly to employ side thrusters to achieve a rapid response and then to hand-over the control to the aerodynamic fins to maintain the desired acceleration command in the steady state ...

• Journal of Astronomy and Space Sciences
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• v.32 no.4
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• pp.379-386
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• 2015

This work presents fuel-optimal altitude maintenance of Low-Earth-Orbit (LEO) spacecrafts experiencing non-negligible air drag and J2 perturbation. A pseudospectral (direct) method is first applied to roughly estimate an optimal fuel consumption strategy, which is employed as an initial guess to precisely determine itself. Based on the physical specifications of KOrea Multi-Purpose SATellite-2 (KOMPSAT-2), a Korean artificial satellite, numerical simulations show that a satellite ascends with full thrust at the early stage of the maneuver period and then descends with null thrust. While the thrust profile is presumably bang-off, it is difficult to precisely determine the switching time by using a pseudospectral method only. This is expected, since the optimal switching epoch does not coincide with one of the collocation points prescribed by the pseudospectral method, in general. As an attempt to precisely determine the switching time and the associated optimal thrust history, a shooting (indirect) method is then employed with the initial guess being obtained through the pseudospectral method. This hybrid process allows the determination of the optimal fuel consumption for LEO spacecrafts and their thrust profiles efficiently and precisely.