• 한국군사과학기술학회지
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• 제23권5호
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• pp.466-474
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• 2020

Semi-active laser missile systems with high accuracy are necessary to asymmetric threats, such as UAV(Unmanned Aerial Vehicle). They are usually used to attack stationary or slow moving targets, therefore we should study on the laser designator which can detect and track fast moving targets in order to deal with UAV. In this study, design specifications are came up through performance analysis of existing laser designators, and laser designation method for fast moving target is developed. The detection and tracking performance of developed laser designator are verified through inside/outside tests on ground/aerial stationary/moving targets. Through this study, we obtain laser designator techniques that could be applied to actual semi-active laser missile systems.

• 한국ITS학회 논문지
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• 제9권2호
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• pp.104-109
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• 2010

본 논문에서는 차량의 무선단말을 이용하여 유선 네트워크와 연결된 정보통신 시스템 서비스를 이용하는 텔레메틱스 환경에서 제3자의 도청이나 공격을 막기 위한 사용자 인증기술을 제안한다. 제안된 사용자 인증방식에서는 차량안의 사용자의 음성신호로부터 생성된 음성 바이오 키를 이용하여 패킷 음성데이터를 암호화하여 정보통신 시스템에 전송하고, 정보통신 시스템 서버에서는 암호화된 패킷 음성데이터로부터 사용자의 음성특징을 복원하여 미리 등록된 사용자의 음성 바이오 키와 비교하여 실시간으로 사용자를 인증한다. 실험을 통해 다양한 공격으로부터 제안된 방식에 대한 안정성을 분석하였다.

• International Journal of Aeronautical and Space Sciences
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• 제17권3호
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• pp.285-295
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• 2016

A contact strip shape of a high speed train pantograph system was optimized with CFD to increase the aerodynamic performance and stability of contact force, and the results were validated by a wind tunnel test. For design of the optimal contact strip shape, a Kriging model and genetic algorithm were used to ensure the global search of the optimal point and reduce the computational cost. To enhance the performance and robustness of the contact strip for high speed pantograph, the drag coefficient and the fluctuation of the lift coefficient along the angle of attack were selected as design objectives. Aerodynamic forces were measured by a load cell and HWA (Hot Wire Anemometer) was used to measure the Strouhal number of wake flow. PIV (Particle Image Velocimetry) was adopted to visualize the flow fields. The optimized contact strip shape was shown a lower drag with smaller fluctuation of vertical lift force than the general shaped contact strip. And the acoustic noise source strength of the optimized contact strip was also reduced. Finally, the reduction amount of drag and noise was assessed when the optimized contact strip was applied to three dimensional pantograph system.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제24회 춘계학술대회논문집
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• pp.394-398
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• 2005

초음속 순항 추진기관인 램제트 추진기관은 $1.5\sim3$ 정도의 비행마하수를 가지는 비행체에 적용되어져 왔고, 마하수 4 이상의 고성능 램제트 추진기관에 대한 연구도 다수 이루어져 왔다. 현재는 극초음속 비행을 위한 램제트-스크램제트 엔진의 작동모드를 가지는 듀얼모드 스크램제트 엔진개발 연구가 활발히 이루어지고 있다. 본 연구에서는 고성능 램제트와 듀얼모드 스크램제트 엔진에 필요한 마하 4에서의 공기흡입구 유동에 대한 연구로서 배압, 받음각, 요각의 변화에 따른 초음속 흡입구에서의 유동 특성을 Schlieren 가시화, Oil 가시화, 압력 측정 등을 통해 파악하였다.

• 한국군사과학기술학회지
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• 제10권4호
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• pp.12-19
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• 2007

In this study, nonlinear flow-induced vibration(flutter) analyses of a 2-DOF launch vehicle airfoil have been conducted in supersonic and hypersonic flow regimes. Advanced aeroelastic analysis system based on computational fluid dynamics and computational structural dynamics is successfully developed and applied to the present analyses. Nonlinear unsteady aerodynamic analyses considering strong shock wave motions are conducted using inviscid Euler equations. Aeroelastic governing equations for the 2-DOF airfoil system is solved by the coupled integration method with interactive CFD and CSD computation procedures. Typical wedge type airfoil shapes with initial angle-of-attacks are considered to investigate the nonlinear flutter characteristics in supersonic(15). Also, the comparison of detailed aeroelastic responses are practically presented as numerical results.

• 한국전산유체공학회지
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• 제16권1호
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• pp.53-59
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• 2011

In this study, steady and unsteady aerodynamic analyses of a huge rocket configuration have been conducted in a transonic flow region. The launch vehicle structural response are coupled with the transonic flow state transitions at the nose of the payload fairing. Before performing the coupled fluid-structure transonic aeroealstic simulations transonic aerodynamic characteristics are investigated for the pitching motions of the rocket at finite angle-of-attack. An unsteady CFD analysis method with a moving grid technique based on the Reynolds-averaged Navier-Stokes equations with the k-w SST transition turbulence model is applied to accurately predict the transonic loads of the rocket at pitching motion. It is shown that the fluctuating amplitude of the lateral aerodynamic loads imposed on the rocket due to the pitching motion can be significantly increased in the transonic flow region.

• Advances in aircraft and spacecraft science
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• 제2권1호
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• pp.45-56
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• 2015

The attitude aerodynamic control is an important subject in the design of an aerospace plane. Usually, at high altitudes, this control is fulfilled by thrusters so that the implementation of an aerodynamic control of the vehicle has the advantage of reducing the amount of thrusters fuel to be loaded on board. In the present paper, the efficiency of a wing-flap has been evaluated considering a NACA 0010 airfoil with a trailing edge flap of length equal to 35% of the chord. Computational tests have been carried out in hypersonic, rarefied flow by a direct simulation Monte Carlo code at the altitudes of 65 and 85 km, in the range of angle of attack 0-40 deg. and with flap deflection equal to 0, 15 and 30 deg.. Effects of the flap deflection have been quantified by the variations of the aerodynamic force and of the longitudinal moment. The shock wave-boundary layer interaction and the shock wave-shock wave interaction have been also considered. A possible interaction of the leading edge shock wave and of the shock wave arising from the vertex of the convex corner, produced on the lower surface of the airfoil when the flap is deflected, generates a shock wave whose intensity is stronger than those of the two interacting shock waves. This produces a consistent increment of pressure and heat flux on the lower surface of the flap, where a thermal protection system is required.

• 한국통신학회논문지
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• 제39C권12호
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• pp.1243-1249
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• 2014

기뢰는 수중에 설치되어 수상함과 잠수함을 공격하기 위한 폭발물로서, 기뢰전은 해군의 여러 가지 성분작전 중에서 매우 중요한 작전 중 하나이다. 본 논문은 기뢰전 일반 개념에 대한 이해로부터 기뢰탐색작전 및 소해작전의 소개와 본문에서 소개 할 몇 가지 기능을 통한 전반적인 기뢰전 체계 설계 방안을 제안한다. 기뢰전 체계의 기능으로는 소나 영상정보로부터 아다부스트 기법을 활용하여 기뢰영역을 탐지하는 기능과 기뢰탐색작전 및 소해작전의 수행 시 각각의 진행률을 계산하는 기능, 소나로부터 수신한 기뢰 표적으로 무인기뢰처리기를 유도하는 기능 등이 있다.

• Journal of Mechanical Science and Technology
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• 제16권3호
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• pp.327-337
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• 2002

This paper applies a recently developed on-line parameter identification (PID) technique to sets of real flight data and compares the results with those of a state-of-the-art off-line PID technique. The on-line PID technique takes Linear Regression from Fourier Transformed equations and the off-line PID is based on the traditional Maximum Likelihood method. Sets of flight data from the NASA F/A-18 High Alpha research Vehicle (HARV) circraft, which has been recorded from specifically designed maneuvers and used for our line parameter estimation, are used for this study. The emphasis is given on the accuracy and on-line measure of reliability of the estimates. The comparison is performed for both longitudinal and lateral-directional dynamics for maneuvers at angles of attack ranging u=20°through $\alpha$=40°. Results of the two estimation processes are also compared with baseline wind tunnel estimates whenever possible.

• 제어로봇시스템학회논문지
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• 제14권12호
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• pp.1205-1211
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• 2008

This paper describes methods to estimate 3-D position of target with respect to reference frame through monocular image from unmanned aerial vehicle (UAV). 3-D position of target is used as information for surveillance, recognition and attack. In this paper. 3-D position of target is estimated to make guidance and control law, which can follow target, user interested. It is necessary that position of target is measured in image to solve 3-D position of target. In this paper, kalman filter is used to track and output position of target in image. Estimation of target's 3-D position is possible using result of image tracking and information of UAV and camera. To estimate this, two algorithms are used. One is methode from arithmetic derivation of dynamics between UAV, carmer, and target. The other is LPV (Linear Parametric Varying). These methods have been run on simulation, and compared in this paper.