• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.245-249
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• 2007

In this study a model-based diagnostic method using the Neural Network was proposed for PW206C turbo shaft engine and performance model was developed by SIMULINK. Fault and test database to build the NN was obtained at various off-design operating range such as flight altitude, flight Mach number and gas generator rotational speed variation. According to the fault detection analysis results, it was confirmed that the proposed fault detection method could find well the fault of compressor, compressor turbine and power turbine at on-design point as well as off-design point conditions.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.3
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• pp.29-34
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• 2007

In this study a model-based diagnostic method using the Neural Network was proposed for PW206C turbo shaft engine and performance model was developed by SIMULINK. Fault and test database to build the NN was obtained at various off-design operating range such as flight altitude, flight Mach number and gas generator rotational speed variation. According to the fault detection analysis results, it was confirmed that the proposed fault detection method could find well the fault of compressor, compressor turbine and power turbine at on-design point as well as off-design point conditions.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.37-42
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• 1999

A compact imaging system, the Multi-spectral Earth Imaging System (MEIS) was developed and operated on an engineering test satellite, KITSAT-3 at the orbital altitude of 720 km. The MEIS takes multi-spectral images of the earth's surface with the swath width of 48 km and the ground sampling distance of 13.8 m in three spectral bands. A brief technical description of the KITSAT-3 MEIS and the result from its initial operation since early June, 1999 are presented. The quality of images produced by the KITSAT-3 MEIS was found comparable to that of images from existing commercial earth observation satellites from its preliminary assessment.

• Electronics and Telecommunications Trends
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• v.18 no.5 s.83
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• pp.52-62
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• 2003

성층권에 무선중계기지를 구축하여 통신에 이용하는 개념은 이미 오래 전부터 제안되어 왔으나 구현상 기술적 난이도가 높아 그 동안 현실화되지 못했다. 그러나 최근 새로운 통신 서비스에 대한 시대적 요구와 고효율의 태양 전지 및 연료 전지, 고정밀 GPS 항법 시스템과 같은 신기술 개발로 인하여 성층권 비행선을 이용한 무선통신 시스템 구현이 점차 가시화 되고 있으며, 세계전파통신회의(WRC)를 계기로 성층권통신시스템용 주파수가 분배됨에 따라, 선진국을 중심으로 HAPS(High Altitude Platform Station) 상용화를 위한 연구개발이 활발히 진행중에 있다. 특히, 우리나라와 인접한 일본은 정부의 적극적인 지원과 산/학/연의 효율적인 공조 체제를 바탕으로 HAPS 개발과 관련하여 과히 세계 선두 진열에 들어서 있다고 해도 과언이 아니다. 아직 HAPS 개발에 필요한 기술적, 재정적 기반이 부족한 우리나라로서는 이웃한 일본의 연구개발 동향을 항시 주시하고 정확하게 분석한다면 향후 독자적인 연구개발 수행 시 많은 도움이 될 것이다.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.1
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• pp.54-60
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• 2009

In this paper, a precision landing approach is implemented based on real-time image processing. A full-scale landmark for automatic landing is used. canny edge detection method is applied to identify the outside quadrilateral while circular hough transform is used for the recognition of inside circle. Position information on the ground landmark is uplinked to the unmanned helicopter via ground control computer in real time so that the unmanned helicopter control the air vehicle for accurate landing approach. Ground test and a couple of flight tests for autonomous landing approach show that the image processing and automatic landing operation system have good performance for the landing approach phase at the altitude of $20m{\sim}1m$ above ground level.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.3 s.18
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• pp.93-100
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• 2004

In this paper, we describe the design, fabrication, and test results of a W-band FMCW radar for the metal target detection under the ground clutter environment. In order to detect metal targets on the ground, we used a single cassegrain antenna with the beamwidth of $1.45^{\circ}$ which forms pencil-beam footprint on the ground. A log envelope detector was applied to improve radar performance in the severe ground clutter known as Weibull and log normal clutter. The designed FMCW radar can acquire altitude information from the ground clutter with $\sigma_0=-23dB$ at the height of 160m. The fabricated W-band FMCW radar transmits 11 dBm power and the dynamic range of the receiver is from -106dBm to -30dBm. The performances of the fabricated sensors were tested out in the fields and detected a car target of 200m apart on the grass.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.9
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• pp.759-768
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• 2016

Design and performance analysis of propeller for solar-powered HALE UAV, EAV-3 are conducted. Experiment points of design variables are obtained by using Design of Experiment(DOE) and Kriging meta-model is generated for objective and constraints function. The geometry of propeller is designed by evaluating the response surface with requirement and restrictions. The validity of the design is verified by meta-model based optimization. Computational analyses are carried out by using commercial CFD code and the results are compared with those from a design code and wind tunnel test. The results showed good agreement with predictions of the design code at the design altitude. Also, it is confirmed that the blockage effect due to the measurement device and support strut is included in the test data and the results including this effect compare well with the test data.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.5
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• pp.99-105
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• 2005

Development of an engine with good fuel economy is very important for successful implementation of long endurance miniature UAVs (unmanned aerial vehicles). In the study, a 4-stroke glow-plug engine was modified to a gasoline-fueled spark-ignition engine. Engine tests measuring performance and friction losses were conducted to tune a simulation program for performance prediction. It has been found that excessive friction losses are caused by insufficient lubrication at high speeds. The simulation program predicts that engine power and fuel economy get worse with high altitude due to increasing portion of friction losses. The simulation results suggest quantitative guidelines for further development of a practical engine.

• Journal of Sensor Science and Technology
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• v.28 no.6
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• pp.345-354
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• 2019

The 3D position of pedestrians is a physical quantity used in various fields, such as automotive navigation and augmented reality. An inertial navigation system (INS) based pedestrian dead reckoning (PDR), hereafter INS-PDR, estimates the relative position of pedestrians using an inertial measurement unit (IMU). Since an INS-PDR integrates the accelerometer signal twice, cumulative errors occur and cause a rapid increase in drifts. Various correction methods have been proposed to reduce drifts. For example, one of the most commonly applied correction method is the zero velocity update (ZUPT). This study investigated the characteristics of the existing INS-PDR methods based on shoe-mounted IMU and compared the estimation performances under various conditions. Four methods were chosen: (i) altitude correction (AC); (ii) step length correction (SLC); (iii) advanced heuristic drift elimination (AHDE); and (iv) magnetometer-based heading correction (MHC). Experimental results reveal that each of the correction methods shows condition-sensitive performance, that is, each method performs better under the test conditions for which the method was developed than it does under other conditions. Nevertheless, AC and AHDE performed better than the SLC and MHC overall. The AC and AHDE methods were complementary to each other, and a combination of the two methods yields better estimation performance.

• IEIE Transactions on Smart Processing and Computing
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• v.6 no.1
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• pp.1-9
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• 2017

This paper proposes to improve the performance of a strap down inertial navigation system using a foot-mounted low-cost inertial measurement unit/magnetometer by configuring an attitude and heading reference system. To track position accurately and for attitude estimations, considering different dynamic constraints, magnetic measurement and a zero velocity update technique is used. A conventional strap down method based on integrating angular rate to determine attitude will inevitably induce long-term drift, while magnetometers are subject to short-term orientation errors. To eliminate this accumulative error, and thus, use the navigation system for a long-duration mission, a hybrid configuration by integrating a miniature micro electromechanical system (MEMS)-based attitude and heading detector with the conventional navigation system is proposed in this paper. The attitude and heading detector is composed of three-axis MEMS accelerometers and three-axis MEMS magnetometers. With an absolute algorithm based on gravity and Earth's magnetic field, rather than an integral algorithm, the attitude detector can obtain an absolute attitude and heading estimation without drift errors, so it can be used to adjust the attitude and orientation of the strap down system. Finally, we verify (by both formula analysis and from test results) that the accumulative errors are effectively eliminated via this hybrid scheme.