• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.9
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• pp.854-864
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• 2016

The use of small drone platform has become a popular topic in these days but its application for SAR operation has been little known due to the burden of the payload implementation. Drone platforms are distinguished from the conventional UAV system by the increased vulnerability to the turbulences, control-errors and poor motion stability. Consequently, sophisticated motion compensation may be required to guarantee the successful acquisition of high quality SAR imagery. Extremely limited power and mass budgets may prevent the use of additional hardwares for motion compensation and the difficulty of SAR focusing is further aggravated. In this paper, we have carried out a feasibility study of mico-SAR drone operation. We present the image acquisition results from the preliminary flight tests and a quality assessment is followed on the experimental SAR images. The in-flight motion errors derived from the unique drone movements are investigated and attempts have been made to compensate for the geometrical and phase errors caused by motions against the nominal trajectory. Finally, the successful operation of drone SAR system is validated through the focussed SAR images taken over test sites.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.640-646
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• 2017

A GEN TEST of the auxiliary power unit of a T-50 series aircraft is performed as part of the operational test of its emergency power system on the ground before flight. At this time, the auxiliary power unit should be automatically turned off via the response signal of the ECU when power is not normally supplied to the emergency power system. If the correct operation of the emergency power system cannot be confirmed on the ground, it is not possible to proceed with the flight. This kind of defect is a major factor causing the operation rate of the aircraft to be decreased. The defect code identified by the ECU was confirmed as a defect in the inverter. However, the same defect was found after replacing the inverter. This report presents an improved method of identifying the cause of the defect by analyzing the response characteristics of the ECU and emergency power system and allows the ECU to be recognized as the cause of the defect if the inverter does not generate a voltage within a certain time. Also, the application of the improved method confirmed that it can satisfy the output request time of the emergency power system and effectively prevent the auto-shutdown of the auxiliary power unit.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.8
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• pp.707-712
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• 2014

Aircraft fuel indicator is a device to indicate the amount of fuel remained during flight, where accurate and consistent operation of the indicator should be maintained. Previously the Korean Utility Helicopter fuel indicator sporadically displayed abnormal sign by "8888" during flight, jeopardizing flight safety. Inappropriate EMI/EMC performance was detected during trouble shooting process. The cause of the abnormal display was found to be resulted from unstable power induced by electro-magnetic disturbance and CAN communication error. The aircraft fuel indicator design was improved and the design compatibility was verified to avoid abnormal display.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.58.1-58.1
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• 2017

The NISS (Near-infrared Imaging Spectrometer for Star formation history) is the near-infrared spectro-photometric instrument optimized to the first Next Generation of small satellite (NEXTSat-1). The off-axis optics was developed to cover a wide field of view with 2 deg. ${\times}$ 2 deg. as well as a wide wavelength range from 0.95 to $2.5{\mu}m$. Considering the simple alignment scheme, afocal system was adapted in the optical components. The mechanical structures were tested under the space environment. We have obtained the accurate calibration data using our test facilities under the operational condition. After the final integration of flight model into the satellite, the communication with the satellite and the functional test were passed. The NISS will be launched in early 2018. During around 2-year operation, the spectro-photometric survey covering more than 100 square degree will be performed. To achieve the major scientific objectives for the study of the cosmic star formation in local and distant universe, the main observational targets will be nearby galaxies, galaxy clusters, star-forming regions and low background regions. Here, we report the final performance of the flight model of the NISS.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.4
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• pp.79-84
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• 2011

This paper presents development activities of the T700/701K turbo-shaft engine for Korean Utility Helicopter(KUH). The T700/701K is the first rear-drive variant of the GE's T700 engine which is proven for military applications in the world. The main workscope of the development includes a modification from a front-drive engine to a rear-drive one, an performance enhancement of the power turbine and an incorporation of two channel FADEC(Full Authority Digital Engine Control) system for more reliable operation. The first engine run for development and qualification test was successfully completed in 2008. Since the PFRT(Preliminary Flight Rating Test) has been completed, the first flight of the engine installed in the first prototype of KUH has been successfully demonstrated in March, 2010 and the engine installation compatibility tests are being carried out during KUH flight test. The test and evaluation for qualification has been done except for the low cycle fatigue test up to date.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.506-511
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• 2010

This paper presents development activities of the T700/701K turbo-shaft engine for Korean Utility Helicopter(KUH). The T700/701K is the first rear-drive variant of the GE's T700 engine which is proven for military applications in the world. The main workscope of the development includes a modification from a front-drive engine to a rear-drive one, an performance enhancement of the power turbine and an incorporation of two channel FADEC(Full Authority Digital Engine Control) system for more reliable operation. The first engine run for development and qualification test was successfully completed in 2008. Since the PFRT(Preliminary Flight Rating Test) has been completed, the first flight of the engine installed in the first prototype of KUH has been successfully demonstrated in March, 2010 and the engine installation compatibility tests are being carried out during KUH flight test. The test and evaluation for qualification of the engine has been done except for the LCF test up to date.

• Journal of Advanced Navigation Technology
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• v.27 no.5
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• pp.495-501
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• 2023

P-3C/K aircraft for maritime patrols that Republic of Korea Navy is using, is equipped with a variety of sensors and communication devices. Collected data from the aircraft is managed as tactical information by flight operators and stored. When the flight mission is completed, this information is transferred to tactical support center on the ground and played back or used for follow-up work through a analysis tool. During a flight mission, there are tens of thousands of detection objects within an hour in KADIZ (Korea air defense identification zone). In contrast, in TSD (tactical situation display), which displays a map when using the analysis tool, all detected objects are expressed as symbols. The increase in display symbols has a significant impact on the TSD image updating and consequently interferes with the smooth operation of operators. In this paper, we propose applying multiple threads and multiple layers to improve the performance of existing TSD. And the performance improvement is proven through the execution results.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.2
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• pp.210-220
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• 2012

The model-free control of aeroelastic vibrations of a non-linear 2-D wing-flap system operating in supersonic flight speed regimes is discussed in this paper. A novel continuous robust controller design yields asymptotically stable vibration suppression in both the pitching and plunging degrees of freedom using the flap deflection as a control input. The controller also ensures that all system states remain bounded at all times during closed-loop operation. A Lyapunov method is used to obtain the global asymptotic stability result. The unsteady aerodynamic load is considered by resourcing to the non-linear Piston Theory Aerodynamics (PTA) modified to account for the effect of the flap deflection. Simulation results demonstrate the performance of the robust control strategy in suppressing dynamic aeroelastic instabilities, such as non-linear flutter and limit cycle oscillations.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.18 no.2
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• pp.46-53
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• 2010

In the aspect of the nature of aircraft maintenance work on divisible tasks carried out by a wide range of operation and expertise, any information transmission problems will not only cause a threat to flight safety but also reduce productivity by keeping the team from fulfilling its mission of delivering aircraft with airworthiness. In this regard, this study firstly identify the current status of information of aircraft maintenance and factors disturbing information transmission. Then, this article also find out the level of information culture of the AMT(Aircraft Maintenance Technicians) and problems in using information. Finally, suggestions on the model of the positive information culture in a field of aircraft maintenance through efficient use of the information including safety will be followed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.165-169
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• 2007

Qualification test range for Lox/Kerosene gas generator cyle liquid rocket engine was determined by considering engine dispersion and flight inlet conditions. With various pump characteristics, the operation range of components and system was investigated through dispersion analysis. The variation of engine performance shows opposite trends in calibration and dispersion.