• 한국통신학회논문지
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• 제39C권11호
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• pp.1011-1022
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• 2014

현 공중노드의 무선네트워크 환경은 지상중계소 중심으로 구축되어 있는 반면에 한반도 환경여건은 전국토의 약 70% 정도가 산악지역으로 이루어져 있어 전파 음영지역(shadow zone)이 다수 존재하는 실정이다. 항공기가 중 저고도 임무 수행 도중 음영지역에 진입되어 통신 링크가 단절되지 않도록 효율적인 대응책 마련이 요구되고 있다. 따라서 본 논문에서는 Bezier Curve를 이용한 항공기 위치예측 및 음영지역 진입제어 방법을 제안한다. 제안된 방법은 항공기 이동경로 예측이 가능하여 음영지역 진입여부를 사전에 진단할 수 있으며 음영지역 진입 이전에 상황을 경고 전파하고 위험지역 이탈조치를 취하는 등 효율적인 제어가 가능하였다. 모의실험결과 제안된 방법은 항공기 위치예측 및 음영지역 진단이 용이하고 위험지역 진입 이전에 이탈조치 함으로써 항공작전 시 끊김 없는(seamless) 통신 지원이 가능한 것으로 나타나고 있다.

• 한국항공우주학회지
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• 제37권11호
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• pp.1104-1111
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• 2009

항공기는 저고도에서 임무를 수행할 때, 대공 미사일과 지형 장애물 같은 다양한 위협들에 제약을 받는다. 특히, 항공기는 지면 근처에서 항상 지형과의 충돌 위험을 갖는다. 본 연구에서는 이 문제에 효과적으로 대비하기 위하여, 지형 회피가 고려된 비행경로 생성 알고리듬을 개발하였다. 비행경로 생성 알고리듬에서는 먼저 등고선의 그룹화를 통해 경로점을 생성하고, Dijkstra 알고리듬을 이용하여 적절한 경로점 조합을 구성한다. 구성된 경로점 조합에 대해서는 최적제어 이론을 기반으로 한 최적 경로점 유도법칙을 적용하여, 제어에너지를 최소로 하는 최적의 비행경로를 제시한다.

• International Journal of Aeronautical and Space Sciences
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• 제6권2호
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• pp.97-109
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• 2005

In this paper, the critical requirement for obstacle awareness and avoidance is assessed with the compliance of the equivalent level of safety regulation, and then the collision avoidance sensor system is presented with the key design parameters for the requirement of the smart unmanned aerial vehicle in low-altitude flight. Based on the assessment of various sensors, small-sized radar sensor is selected for the suitable candidate due to the real-time range and range-rate acquisition capability of the stationary and moving aircraft even under all-weather environments. Through the performance analysis for the system requirement, the conceptual design result of radar sensor model is proposed with the range detection probability and collision avoidance mode is established based on the time-to-collision, which is analyzed by collision scenario.

• 한국항공운항학회지
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• 제20권2호
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• pp.26-31
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• 2012

A new operational concept for the CNS/ATM using the digital data communication technology and satellite navigation system is being implemented globally and the United States is the first country to apply UAT ADS-B system for general aviation. Korea also has plan to build ADS-B system for aeronautical surveillance to monitor low altitude flight of light aircraft and ultra-light flying device and the research to develop UAT ADS-B equipment is being carried out. This paper presents the application method of UAT ADS-B to support test operation with case study of foreign UAT ADS-B operation and survey of domestic environment.

• 대한원격탐사학회지
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• 제7권2호
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• pp.149-163
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• 1991

This paper discusses the capabilities of airborne remotely sensed data to detect and classify forest damades. In this work the AMS (Aircraft Multiband Scanner) was used to obtain digital imagery at 300m altitude for forest damage inventory in the Black Forest of Germany. MSS(Multispectral Scanner) digital numbers were converted to spectral emittance and radiance values in 8 spectral bands from the visible to the thermal infrared and submitted to a maximum-likelihood classification for : (1) tree species ; and. (2) damage classes. As expected, the resulted, the results of MSS data with high spatial resolution 0.75m$\times$0.75m enabled the detection and identification of single trees with different damages and were nearly equivalent to the truth information of ground checked data.

• 한국측량학회지
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• 제34권5호
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• pp.535-544
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• 2016

기존의 정사영상 제작에서는 고가의 항공기를 이용한 대규모 지역에 대해서만 경제적인 정사영상을 제작할 수 있었으며, 지형지물에 대해 빠르게 변화를 갱신하지 못한다는 단점이 있었다. 하지만 최근 무인항공기(UAV: Unmanned Aerial Vehicle)가 빠른 속도로 발전되고, GPS와 IMU 등의 다양한 센서 탑재로 고가의 항공사진측량을 대체할 수 있다는 평가를 받고 있다. 무인항공기를 이용하여 소규모 지역에 대한 정사영상 지도를 제작 할 경우 신속하게 공간정보를 갱신할 수 있다는 장점을 가지고 있지만 기존 연구의 경우 같은 고도의 영상으로만 정사영상을 제작하여 자료의 중복성과 자료 갱신에 대한 단점이 있다. 본 연구에서는 소규모 경사지역을 대상으로 저가용 무인항공기의 고도가 다른 영상을 통해 정사영상 및 DEM(Digital Elevation Model)을 제작하였다. 검사점에 의한 수평 및 수직 성분의 RMSE는 σ_h = 0.023m, σ_v = 0.049m 의 정확도를 보여 국토지리정보원 수치지도 1/500 축척의 RMSE와 최댓값 허용범위를 만족하였다. 이를 통해 고도가 다른 영상을 이용하여 높은 정확도의 정사영상을 제작할 수 있었으며, 다양한 고도의 자료를 통해 자료의 중복성을 줄이고, 신속하게 공간정보를 제공할 수 있음을 확인하였다.

• 한국항공운항학회지
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• 제28권1호
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• pp.1-6
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• 2020

The purpose of this study is to analyze the radiation dose data of the space crew of the flight crew and to present a plan for the health management of the flight crew on the basis of the analysis. The analysis show that the average exposure dose of the flight attendants continued to rise, and the exposure dose of the flight attendants was five(5) times higher than that of the radiation workers. As a way to reduce the effects of cosmic radiation, this paper suggests appropriate personnel allocation by model, balanced allocation of high and low latitude routes by crew according to the aircraft type, and a low altitude flight plan for high latitude flight. This study will help aviation crew members understand cosmic radiation and trust in the company's policies. In the future, it will be necessary to enhance the flight safety of the crew by deriving meaningful results by analyzing data related to cosmic radiation of various routes.

• 항공우주시스템공학회지
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• 제10권1호
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• pp.59-65
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• 2016

Korea Aerospace Research Institute (KARI) is developing an electric-driven HALE UAV in order to secure system and operational technologies since 2010. Based on the 5 years of flight tests and design experiences of the previously developed electric-driven UAVs, KARI has designed EAV-3, a solar-powered HALE UAV. EAV-3 weighs 53 kg, the structure weight is 21 kg, and features a flexible wing of 19.5 m in span with the aspect ratio of 17.4. Designing the main wing and empennage of the EAV-3 the amount of the bending due to the flexible wing, 404 mm at 1-G flight condition based on T-800 composite material, and side wind effects due to low cruise speed, V_cr = 6 m/sec, are carefully considered. Also, unlike the general aircraft there is no center of gravity shift during the flight. Thus, the static margin cuts down to 28.4% and center of gravity moves back to 31% of the Mean Aerodynamic Chord (MAC) comparing to the previously developed scale-down HALE UAVs, EAV-2 and EAV-2H, to minimize a trim drag and enhance a performance of the EAV-3. The first flight of the EAV-3 has successfully conducted on the July 29, 2015 and the test flight above the altitude 14 km has efficiently achieved on the August 5, 2015 at the Goheung aviation center.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.690-699
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• 2008

In this paper a conventional approach for design and analysis of subsonic air vehicle is used. First of all subsonic aerodynamic coefficients are calculated using Computational Fluid Dynamics(CFD) tools and then wind-tunnel model was developed that integrates vehicle components including control surfaces and initial data is validated as well as refined to enhance aerodynamic efficiency of control surfaces. Experimental data and limited computational fluid dynamics solutions were obtained over a Mach number range of 0.5 to 0.8. The experimental data show the component build-up effects and the aerodynamic characteristics of the fully integrated configurations, including control surface effectiveness. The aerodynamic performance of the fully integrated configurations is comparable to previously tested subsonic vehicle models. Mathematical model of the dynamic equations in 6-Degree of Freedom(DOF) is then simulated using MATLAB/SIMULINK to simulate trajectory of vehicle. Effect of altitude on range, Mach no and stability is also shown. The approach presented here is suitable enough for preliminary conceptual design. The trajectory evaluation method devised accurately predicted the performance for the air vehicle studied. Formulas for the aerodynamic coefficients for this model are constructed to include the effects of several different aspects contributing to the aerodynamic performance of the vehicle. Characteristic parameter values of the model are compared with those found in a different set of similar air vehicle simulations. We execute a set of example problems which solve the dynamic equations to find the aircraft trajectory given specified control inputs.

• Advances in aircraft and spacecraft science
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• 제6권3호
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• pp.239-256
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• 2019

This study develops a dual purpose: i) evaluating the effects of two different Mars atmosphere models (NASA Glenn and GRAM-2001) on aerodynamics of a capsule (Pathfinder) entering the Mars atmosphere, ii) verifying the feasibility of evaluating the ambient density and pressure by means of the methods by McLaughlin and Cassanto, respectively and therefore to re-build the values provided by the models. The method by McLaughlin relies on the evaluation of the capsule drag coefficient, the method by Cassanto relies on the measurement of pressure at a point on the capsule surface in aerodynamic shadow. The study has been carried out computationally by means of: i) a code integrating the equations of dynamics of the capsule for the computation of the entry trajectory, ii) a DSMC code for the solution of the flow field around the capsule in the altitude interval 50-100 km. The models show consistent differences at altitudes higher than about 40 km. It seems that the GRAM-2001 model is more reliable than the NASA Glenn model. In fact, the NASA Glenn model produces, at high altitude, temperatures that seem to be too low compared with those from the GRAM-2001 model and correspondingly very different aerodynamic conditions in terms of Mach, Reynolds and Knudsen numbers. This produces pretty different capsule drag coefficients by the two models as well as pressure on its surface, making not feasible neither the method by McLaughlin nor that by Cassanto, until a single, reliable model of the Mars atmosphere is not established. The present study verified that the implementation of the Cassanto method in Mars atmosphere should rely (such as it is currently) on pressure obtained experimentally in ground facilities.