• Journal of Mechanical Science and Technology
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• v.19 no.8
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• pp.1529-1543
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• 2005

Recently an unmanned aerial vehicle (UAV) has been widely used for military and civil applications. The role of a navigation system in the UAV is to provide navigation data to the flight control computer (FCC) for guidance and control. Since performance of the FCC is highly reliant on the navigation data, a fault in the navigation system may lead to a disastrous failure of the whole UAV. Therefore, the navigation system should possess a fault detection and isolation (FDI) algorithm. This paper proposes an attitude determination GPS/INS integrated navigation system with an FDI algorithm for a UAV. Hardware for the proposed navigation system has been developed. The developed hardware comprises a commercial inertial measurement unit (IMU) and the integrated navigation package (INP) which includes an attitude determination GPS (ADGPS) receiver and a navigation computer unit (NCU). The navigation algorithm was implemented in a real-time operating system with a multi-tasking structure. To evaluate performance of the proposed navigation system, a flight test has been performed using a small aircraft. The test results show that the proposed navigation system can give accurate navigation results even in a high dynamic environment.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.30 no.2
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• pp.24-33
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• 2022

This study analyzed and derived a plan to reduce fuel consumption of domestic aircraft. Specifically, this study tested fuel consumption in the short-distance flights of B737. Fuel consumption was calculated by substituting the simulation variable values into Matlab. The strength of this study is that the actual operating environment was reflected by collecting the B737 flight data. As a result of the study, the domestic fuel consumption rate in the computed flight plan was less than the current fuel consumption rate. Existing limitations of this study is that it was difficult to reflect the various variables constituting the flight environment, and thus there can be errors in the measurement of the fuel consumption. There are two major expected applications from this study. First, applying the plans from this study will lead to a reduction in the amount of fuel and thus provide positive economic effects for commercial airlines. Second, the plan from this study will provide a basis for pilots to predict fuel consumption more accurately. In conclusion, this study proposes a fuel saving plan with useful applications for pilots and airlines.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.7
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• pp.497-504
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• 2020

A technique was developed for analysis on sonic boom created by supersonic flight and for prediction of its sound level and atmospheric propagation characteristics. It is of great importance to anticipate sound level of sonic boom because it causes environmental issue. For that purpose, the simplified sonic-boom prediction method was applied to calculate sound pressure according to physical properties and flight information of the object and distance to measurement site, in this study. Propagation characteristics of shock wave emanated from a flying object was analyzed by using line-of-sight vector and ray tracing method which dealt with refraction of wave due to atmospheric density distribution along altitude. Predicted results agreed well with measured data from real flight.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.746-749
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• 2002

This paper is introducing a radio control helicopter as a new platform of ground truth measurement. This helicopter is normally used for spraying an agricultural chemical. It can do pinpoint hovering and programing flight using DGPS etc., A spectrometer with dual port can measure ground surface and white reference plate at the same time. And it can also take digital images by digital camera. It is needed to collect ground reflectance information as satellite sensor footprint size for satellite data validation. Generally it is possible to get such ground reflectance by an airplane measurement. But it is high cost and not so easy to make a measurement by airplane. Developed validation system can provide such ground reflectance in low cost and easy.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.489-493
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• 2004

The Modulation Transfer Function (MTF) is commonly used to characterize the spatial quality of imaging systems. This work is the attempt to measure the MTF for KOMPSAT EOC using the non-parametric method as ground inputs. The spatial performance of the KOMPSAT EOC was analyzed by edge method while in flight using multi-temporal image data collected over test site in Seoul. The results from this work demonstrate the potential applicability of this method to estimate MTF for high spatial resolution satellite KOMPSAT-2 that is being developed to be launched in 2005.

• Proceedings of the Korea Contents Association Conference
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• 2004.11a
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• pp.495-500
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• 2004

The neutron capture cross section of $^{99}Tc$ has been measured relative to the $^{10}B$(n,g) standard cross section by the neutron time-of-flight(TOF) method in the energy range of 0.007 eV to 47keV using a 46-MeV electron linear accelerator(linac) at the Research Reactor Institute, Kyoto University(KURRI). In order to experimentally prove the result obtained, the supplementary cross section measurement has been made from 0.3 eV to 1 keV using the Kyoto University Lead slowing-down Spectrometer(KULS) coupling to the linac. The relative measurement by the TOF method has been normalized to the reference value(20.01 b) at 0.0253 eV and the KULS measurement to that by the TOF method. The existing experimental data and the evaluated capture cross sections in ENDF/B-VI, JENDL-3.2, and JEF-2.2 have been compared with the current measurements by the linac TOF and the KULS experiments. The energy dependency of the KULS data is close to that of the TOF data which are energy-broadened by the resolution function of the KULS.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.6
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• pp.565-573
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• 2020

Unlike fin-stabilized projectiles, there has been some difficulty measuring the attitudes of spin-stabilized projectiles during the long-range flight due to their high spin rates. In this work, solar and geomagnetic sensors were used to measure the attitude of a spin-stabilized projectile. A method to calculate the attitude of the projectile from the signals of the sensors was introduced as well as the methods to process the signals of the sensors. To validate the methods, the attitude of a projectile was calculated with the sensor signals from the actual flight data.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.156.4-156
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• 2001

The uncertainties of an atmospheric re-entry flight with respect to stability and controllability are aerodynamic error, measurement error of the angle of attack, variation of dynamic pressure, wind, and trim position of the control surfaces, etc. During hypersonic flight, a future angle of attack is biased from a nominal schedule. In order words, because the angle of attack is estimated from the navigation data, estimation error occurs due to wind, atmospheric density variation, etc. Error models used in this study, include a standard deviation of +-3 sigma, and are the normal distribution of statistics. This paper shows the appraisement of tracking performance onto the reference trajectory, satisfaction of the initial condition of TAEM about the re-entry system.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.265-270
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• 2006

Recently, inertial sensors like gyros and accelerometers have been quite miniaturized by Micro Electro-Mechanical Systems (MEMS) technology. JAXA is developing a MEM-based GPS/INS hybrid navigation system named Micro-GAIA. The navigation performance of Micro-GAIA was evaluated through off-line analysis by using flight test data. The estimation errors of the roll, pitch, and azimuth were $0.03^{\circ}$, $0.05^{\circ}$, $0.05^{\circ}$ $(1{\sigma})$, respectively. he horizontal position errors after 60-second GPS outages were reduced to 25 m CEP. The attitude errors and position errors are nearly half of ones reported previously[2]. Furthermore, using the adaptive Kalman filters, the robustness against the uncertainty of the measurement noise was improved. Comparing the innovation-based and residual-based adaptive Kalman filters, it was confirmed that the latter is robuster than the former.

• Journal of the Semiconductor & Display Technology
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• v.19 no.1
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• pp.11-16
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• 2020

In this paper, system that includes multiple unmanned aerial vehicles (UAVs) are considered. The vehicles are equipped with a mission computer for a specific mission and equipment. The mission equipment operates based on the time of mission computer. Also, data collected by flight computer and mission computer is saved with the time of each operating system. Generally, time offset between multiple computers always exists, though the computers are connected to the Internet. When the data collected by multiple computers is combined, the time offset causes damage on reliability of the combined data. Computers that connected to the Internet are synchronized by network time protocol (NTP). This paper proposes a system that the time of multiple mission computers are synchronized by the same NTP server to minimize the time offset. In the results of the measurement, the system time offset of multiple mission computer is maintained within 10ms from the system time of the server computer.