• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2006년도 추계 학술대회논문집
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• pp.24-25
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• 2006

An unstructured mesh method has been developed for the simulation of steady and time-accurate flows around helicopter rotors. A dynamic and quasi-unsteady solution-adaptive mesh refinement technique was adopted for the enhancement of the solution accuracy in the local region of interest involving highly vortical flows. Applications were made to the 2-D blade-vortex interaction aerodynamics and the 3-D rotor blades in hover. The interaction between the rotor and the airframe in forward flight was investigated by introducing an overset mesh technique.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.567-571
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• 1992

A guidance loop of the missile system which uses a command to line of sight(CLOS) guidance law is designed based on LQG theory. In the environment of the severe tracking system noise, the system requires small aerodynamic control fin travel and small miss distance simultaneously. Results from a sample airframe shows good performance against a randomly maneuvering target.

• 한국항공우주학회지
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• 제42권5호
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• pp.415-422
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• 2014

군용 헬기 내추락성 설계기준을 개정해야 한다는 많은 논의가 있어 왔다. 본 논문에서는 비교적 최근에 개정된 내추락성 설계기준을 핵심내용인 내추락성 지수를 중심으로 분석하였다. 내추락성 지수는 회전익기 설계에 있어서의 내추락 성능을 정량적으로 평가하는 적절한 방법으로 인식되고 있다. 지수 평가를 통해 신규개발 또는 파생형 회전익기 설계가 얼마나 효과적으로 내추락성 요구조건을 반영했는지 확인할 수 있다. 지수 평가는 7개 분야로 구성되어 있는데, 기본 기체구조 내추락성 평가는 객관적인 계산과정을 겪는데 반해 나머지 분야들은 다분히 주관적 평가의 속성을 갖고 있다. 따라서 본 논문에서는 개정 설계기준의 효용성을 파악하기 위해 기본 기체구조 내추락성 분야 내추락성 지수의 상세 계산과정을 분석하였다.

• 한국항공우주학회지
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• 제33권6호
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• pp.83-91
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• 2005

본 논문은 초음속 환경에서 운용되는 원통형 비행체가 비행중 경험하는 공력하중 및 공력가열 현상을 지상에서 유사하게 모사하기 위한 내열구조시험 기법 및 시험결과에 대하여 기술하였다. 시험 중 시험 구조물의 자세를 공중에서 제어하거나 시험 중지 중 시험 구조물을 지지할 목적으로 스프링을 이용하는 특별한 자세제어장치가 설계되었다. 시험 구조물에 공력하중과 열하중을 부가하기 위하여 유압식 외력하중부가 장비와 전기식 열부가 장비를 사용하였다. 특히, 복사방식의 수백 개 석영램프가 열부가장비에 응용되었으며, 이들을 이용하여 여러 가지의 열특성 시험조건이 해석조건과 유사하게 지상에서 성공적으로 구현되었다. 연구결과 본 내열구조강도시험기법은 외력 및 극심한 열하중에 노출된 원통형 구조물의 구조적 건전성을 실험적 방법에 의거 지상에서 검증하거나 설계 개선에 필요한 공학자료를 획득하는데 적합한 방법임이 입증되었다.

• 대한임베디드공학회논문지
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• 제15권3호
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• pp.149-157
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• 2020

Regarding previously-developed drone simulators, it was easy to check their flight stability or controlling functions based on the condition that their weight was fixed from the design. However, the drone is largely classified into two types that is the one with the fixed weight whose purpose is recording video with camera and racing and another is whole weight-variable during flight with loading the articles for delivery and spraying pesticide though the weight of airframe is fixed. The purpose of this thesis is to analyze the structure of drone and its flight principle, suggest dynamics-model-based simulator that is capable of simulating weight-variable drone and develop the simulator that can be used for designing main control board, motor and transmission along the application of weight-variable drone. Weight-variable simulator was developed by using various calculation to apply flying method of drone to the simulator. First, ground coordinate system and airframe-fixing coordinate system were established and switching matrix of those two coordinates were made. Then, dynamics model of drone was established using the law of Newton and moment balance principle. Dynamics model was established in Simulink platform and simulation experiment was carried out by changing the weight of drone. In order to evaluate the validity of developed weight-variable simulator, it was compared to the results of clean flight public simulator against existing weight-fixed drone. Lastly, simulation test was performed with the developed weight-variable simulation by changing the weight of drone. It was found out that dynamics model controlled various flying positions of drone well from simulation and the possibility of securing the optimum condition of weight-variable drone that has flying stability and easiness of controlling.

• 융합보안논문지
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• 제20권2호
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• pp.145-153
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• 2020

2018년부터 시행된 항공안전정책기본계획은 무결점 항공안전관리체계 구축과 미래 항공안전 인프라 구축을 목표로 4차 산업혁명 기술을 적용한 항공안전관리 기술 개발을 포함하고 있다. 인공지능과 빅데이터를 활용한 항공기 고장관리, 가상/증강현실 기술을 활용한 비행훈련체계 등 다양한 항공안전관리 체계를 구축하고자 한다. 현재 공군에서도 스마트한 공군력 건설이라는 목표 아래 신기술을 활용한 비행안전관리 체계 사업을 추진 중이다. 본 연구에서는 비행 전에 항공기의 최종 안전성을 점검하는 항공기 상태 점검체계를 4차 산업혁명기술을 적용하여 설계하고자 한다. 공군에서는 항공기 상태 점검으로 기골 결함 점검과 비행 전 항공기 종합점검을 실시한다. 본 연구에서는 최소한 점검 오류를 줄일 수 있는 무결점 점검을 위해서 인공지능, 사물인터넷, 빅데이터, 그리고 드론을 활용한 기골 결함 점검체계와 비행 전 항공기 상태 점검체계 설계를 제안한다.

• 한국측량학회지
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• 제37권5호
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• pp.379-388
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• 2019

Recently, a technique for acquiring spatial information data using UAV (Unmanned Aerial Vehicle) has been greatly developed. It is a very crucial issue of the GIS (Geographic Information System) mapping system that passes way point in the unmanned airframe and finally measures the accurate image and stable localization to the desired destination. Though positioning using DGPS (Differential Global Navigation System) or RTK-GPS (Real Time Kinematic-GPS) guarantee highly accurate, they are more expensive than the construction of a single positioning system using a single GPS. In the case of a low-priced single GPS system, the stability of the positioning data deteriorates. Therefore, it is necessary to supplement the uncertainty of the absolute position data of the UAV and to improve the accuracy of the current position data economically in the operating state of the UAV. The aim of this study was to present an algorithm enhancing the stability of position data in a single GPS mode of UAV with multiple GPS. First, the arrangement of multiple GPS receivers through the center of gravity of the UAV were examined. Next, MD (Mahalanobis Distance) is applied to detect instantaneous errors of GPS data in advance and eliminate outliers to increase the accuracy of previously collected multiple GPS data. Processing procedure for multiple GPS reception data by applying the center of the triangular method were presented to improve the position accuracy. Second, UAV navigation systems integrated multiple GPS through configuration of the UAV specifications were implemented. Using the unmanned airframe equipped with multiple GPS receivers, GPS data is measured with the TCM (Triangular Center Method). In addition, UAV equipped with multiple GPS were operated in study area and locational accuracy of multiple GPS of UAV with VRS (Virtual Reference Station) GNSS surveying were compared. The result showed that the error factors are compensated, and the error range are reduced, resulting in the reliability of the corrected value. In conclusion, the result in this paper is expected to realize high-precision position estimation at low cost in UAV using multiple low-cost GPS receivers.

• Transactions on Control, Automation and Systems Engineering
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• 제4권2호
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• pp.114-123
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• 2002

Called VISTA (Variable-stability In-flight Simulator Test Aircraft), the one-of-a-kind NF-l6D has a simulation system that can mimic several aircraft. Though housed in an F-l6 Fighting Falcon airframe, VISTA can also act like the F-15 Eagle or the Navy's F-14 Tomcat. More importantly, such flexibility allows for improved training and consolidation of some sorties. Consequently USAF Test Pilot School students will have an opportunity to learn how to test future integrated cockpits. In this paper we will use the multiple model adaptive estimation (MMAE) and the multiple model adaptive controller (MMAC) techniques to model the aircraft's flight control system containing the longitudinal and lateral-directional axes. Single and dual actuator and sensor failures will also be included in the simulation. White Gaussian noise will be included to simulate the effects of atmospheric disturbances.

• 한국군사과학기술학회지
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• 제16권2호
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• pp.111-117
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• 2013

In this paper, we have proposed novel technique to improve maintainability for training vehicle of underwater weapon system. In case of under water weapon, the fire procedure is related with operation of expulsion system in submarines. So the submarine crews should practice the complex fire procedure of weapon system by using training vehicle, which is safer and cheaper than operational weapon. After emitted from submarine, the training vehicle rise to the surface and should be withdrawn from the sea. The recovered training vehicle is transported to maintenance depot and pass through the recycling procedure including disassembling the vehicle, data acquisition & analysis, battery charge, replacing expandable components, testing the captive equipment, and assembling the vehicle. The disassembling & assembling of training vehicle which is composed of watertight section or airframe, is time-consuming work. So in this paper, we have studied the elements of recycling procedure and propose the method to exclude the assembling & disassembling work for maintainability improvement.

• Structural Engineering and Mechanics
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• 제65권5호
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• pp.513-521
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• 2018

In this paper, the resonance response of spar-type floating platform in coupled heave and pitch motion is investigated using a CPU time-effective numerical method. A coupled nonlinear 2-DOF equation of motion is derived based on the potential wave theory and the rigid-body hydrodynamics. The transient responses are solved by the fourth-order Runge-Kutta (RK4) method and transformed to the frequency responses by the digital Fourier transform (DFT), and the first-order approximation of heave response is analytically derived. Through the numerical experiments, the theoretical derivation and the numerical formulation are verified from the comparison with the commercial software AQWA. And, the frequencies of resonance arising from the nonlinear coupling between heave and pitch motions are investigated and justified from the comparison with the analytically derived first-order approximation of heave response.