• Journal of the Korea Convergence Society
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• v.8 no.6
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• pp.219-226
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• 2017

As the UAV industry is getting matured, various types of UAVs have appeared in many application fields, including filming, reconnaissance, rescue, and etc. and it requires the quick hardware designs, particularly a battery pack, of the UAV. We developed the automatic battery pack design tool for the convenient battery pack configuration design of the hoverable type delivery UAV. With inputs, including current profile, voltage profile, various kinds of cell specifications, desired battery pack voltage, and etc. the automatic battery pack design tool calculates a pack having the minimum weight and the maximum capacity by combining either homogeneous cells or heterogeneous cells. Also, the tool could predict the capacity fading trend of the designed battery pack configuration.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.554-559
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• 2017

Recently, the global attention is focused on the development of the renewal aero-propulsion systems proved in the air pollution, the noise, the great operational cost, safety and risks. Especially, various study are conducting for the development of the advanced high power to weight ratio aircraft through the significant reduction of fuel consumption and upgrade of the propulsion efficiency, using the alternative propulsion system developments such as hydrogen and solar power system. The hybrid propulsion system can be the representative propulsion system which get the power sources by combining the merits of two or more power sources. In this study, the advancement trends, characteristics, design method which can be applied to the renewal future UAV development.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.4
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• pp.133-140
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• 2018

Recently, environmentally friendly aviation propulsion systems have received a lot of attention. Therefore, many studies have been conducted on the development of UAVs and propulsion systems that can perform missions while relying on a combination of various power sources. In this paper, we show the design results of a hybrid propulsion system based on solar-power generation. It integrates a single system to test reliability and performance. Finally, a verification test is conducted on the aircraft to confirm the function and normal operation of the system before a flight test.

• Korean Journal of Remote Sensing
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• v.36 no.5_3
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• pp.1013-1025
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• 2020

Unmanned Aerial Vehicle (UAV) platform is being widely used in disaster monitoring and smart city, having the advantage of being able to quickly acquire images in small areas at a low cost. Ground Control Points (GCPs) for positioning UAV images are essential to acquire cm-level accuracy when producing UAV-based orthoimages and Digital Surface Model (DSM). However, the on-site acquisition of GCPs takes considerable manpower and time. This research aims to provide an efficient and accurate way to replace the on-site GNSS surveying with three different sources of geospatial data. The three geospatial data used in this study is as follows; 1) 25 cm aerial orthoimages, and Digital Elevation Model (DEM) based on 1:1000 digital topographic map, 2) point cloud data acquired by Mobile Mapping System (MMS), and 3) hybrid point cloud data created by merging MMS data with UAV data. For each dataset a three-dimensional positional accuracy analysis of UAV-based orthoimage and DSM was performed by comparing differences in three-dimensional coordinates of independent check point obtained with those of the RTK-GNSS survey. The result shows the third case, in which MMS data and UAV data combined, to be the most accurate, showing an RMSE accuracy of 8.9 cm in horizontal and 24.5 cm in vertical, respectively. In addition, it has been shown that the distribution of geospatial GCPs has more sensitive on the vertical accuracy than on horizontal accuracy.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.11
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• pp.940-947
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• 2012

The target system is a middle size UAV, which is a low-speed long-endurance UAV with a weight of 18 kg and wingspan of 6.4 m. Three electric power sources, i.e. solar cells, a fuel cell, and a battery, are considered. The optimal takeoff time is determined to maximize the endurance because the generated solar cell's energy is heavily dependent on it. Each power source is modeled in Matlab/Simulink, and the component models are verified with the component test data. The component models are integrated into a power system which is used for power simulations. When takeoff time is at 6 pm and 2 am, it can supply the power during 37.5 hrs and 27.6 hrs, respectively. In addition, the thermostat control simulation for fuel cell demonstrates that it yields more power supply and efficient power distribution.

• Journal of Aerospace System Engineering
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• v.18 no.3
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• pp.48-55
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• 2024

In recent years, as the commercialization of unmanned aerial vehicles (UAVs) has been actively promoted, much attention has been focused on developing a technology to ensure the safety of UAVs. In general, the UAV has the potential to enter an uncontrollable state caused by sudden maneuvers, disturbances, and pilot error. To prevent entering an uncontrolled situation, it is essential to predict the flight state of the UAV. In this paper, we propose a flight state prediction technique based on an improved CNN-LSTM hybrid mode to enhance the flight state prediction performance. Simulation results show that the proposed prediction technique offers better state prediction performance than the existing prediction technique, and can be operated in real-time in an on-board environment.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.4
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• pp.374-382
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• 2014

This paper presents the computational aerodynamic analysis of a long-endurance UAV that was developed by the Korea Aerospace Research Institute (KARI), named EAV-2. EAV-2 is a technical demonstrator of aerodynamically efficient design, as well as a hybrid electric-propulsion system for future long-endurance UAVs. We evaluated the aerodynamic characteristics of six low-Reynolds number airfoils, using a panel method code, XFOIL, to select an optimal airfoil for the long-endurance mission of EAV-2. The computational results by a CFD code, FLUENT, suggested that the aerodynamic performance of EAV-2 would be notably improved after adopting SG6043 airfoil, and modifying the fuselage design. This reduced the total drag by 43%, compared to that of a previous KARI model, EAV-1, at the target lift of $C_L=1.0$. Also, we achieved a drag reduction of approximately 14% by means of the low-drag fuselage configuration.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.3
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• pp.200-206
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• 2005

In this paper, a redundancy management system for aircraft is studied, and FDI (Fault Detection and Isolation) algorithm of inertial sensor system is proposed. UAV system cannot allow triple or quadruple hardware redundancy due to the limitations on space and weight. In the UAV system with dual sensors, it is very difficult to identify the faulty sensor. Also, conventional FDI method cannot isolate multiple faults in a triple redundancy system. In this paper, hardware based FDI technique is proposed, which combines a parity equation approach with the wavelet based technique, which is a model-free FDI method. To verify the effectiveness of the proposed FDI method, numerical simulations are performed.

• Proceedings of the Korea Society for Simulation Conference
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• 2005.11a
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• pp.159-164
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• 2005

UAV(Unmanned Air Vehicle) 시스템은 새로운 알고리즘과 소프트웨어 디자인에 바탕을 두고 빠르게 발전하고 있다. 그러나, 일반적으로 쓰이고 있는 전자공학적인 제어 시스템은 개발의 복잡성과 그에 따른 이용증대에 대한 문제점을 가지고 있다. 이에 본 논문에서는 연속시간 시스템으로 표현되는 비행기 모델과 이의 효과적인 제어를 위해 이산사건 시스템으로 표현되는 조종사 모델간의 연동을 제안한다. 전자공학적 모델인 연속시스템은 자세한 표현력을 바탕으로 정량적이고 정확한 비행기 모델을 표현할 수 있으며 제어 모델인 이산사건 시스템은 각 사건과 시스템의 상태에 따른 정성적인 행동제어를 가능하게 한다. 본 연구는 한국항공대학교에서 개발한 이산사건 시뮬레이터인 DEJAVA(DEVS Java)와 연속시간시뮬레이터인 MATLAB 시뮬레이터 환경을 바탕으로, NASA에서 개발된 HL2O 비행시뮬레이터와 조종사 모델을 위한 지능제어시스템 개념을 사용하여 구현되었다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.579-582
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• 2008

PEM Fuel cell system was designed and constructed to use as a power source of unmanned aerial vehicles(UAV) in the present study. Sodium borohydride was selected as a hydrogen source and was decomposed by catalytic hydrolysis reaction. Fuel cell system consists of a fuel cell stack, a hydrogen generation system(HGS), and power management system(PMS). HGS was composed of a catalytic reactor, micropump, fuel cartridge, and separator. Hybrid power system between lithium-polymer battery and fuel cell was developed. The fuel cell system was integrated and packaged into a blended wing-body UAV. Energy density of the total system was 1,000 $W{\cdot}hr/kg$ and high endurance more than 5 hours was accomplished in the ground tests.