• Aerospace Industry
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• s.94
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• pp.46-49
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• 2007

레이더가 만들어지고 나서 항공전에는 적에게 노출이 도지 않는 은폐 기술 즉, 스텔스 성능을 군관계자들은 요구해 왔다, 이번호에는 최근 개발된 항공기에 보편화되고 있는 기능인 스텔스 성능은 무엇인지 알아본다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.1
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• pp.63-69
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• 2015

In this paper, infrared reflector design targeting infrared stealth effect is presented using structural optimization based on the phase field method. The analysis model was determined to accomplish the design that an incident infrared wave was reflected to a desired direction. The design process was to maximize the objective value at the measuring domain located in a target region and the design objective was set to the Poynting vector value which represents the energy flux. Optimization results were obtained according to the variation of some parameter values related to the phase field method. The model with a maximum objective value was selected as the final optimal model. The optimal model was modified to eliminate the gray scale using the cut-off method and it confirmed improved performance. In addition, to check the desired effect in the middle wave infrared range(MWIR), the analysis was performed by changing the input wavelength. The finite element analysis and optimization process were performed by using the commercial package COMSOL combined with the Matlab programming.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.2
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• pp.255-263
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• 2017

An infrared-guided missile has been emerging as a major threat against combat aircraft due to its passive guidance characteristics and with recent advances in stealth technology. Hence, the infrared stealth technology and its effectiveness-evaluation technique become more significant than ever before. In this study, we applied missile aerodynamics to lethal range calculation which allowed more precise prediction. CFD analyses were newly involved in estimating drag force characteristics of an infrared-guided missile. Velocity profiles during flight period of the missile were constructed utilizing these drag characteristics and then incorporated into our in-house code to predict corresponding lethal ranges. The results showed that the present method can predict lethal range more appropriately than the previous one with constant velocity profile. As one of the results, if a fighter gains altitude more which reduces less drag of the attacking missile, then the lethal envelope increases significantly more compared to the lock-on envelope.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.5
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• pp.455-461
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• 2016

Survivability of an aircraft has been greatly threatened by the development of a weapon system using infrared. Therefore, the infrared stealth technology is a very important technique to improve the survivability of an aircraft. In this study, the infrared signal of an aircraft was analyzed which corresponding to the aircraft surface temperature and environmental conditions with various surface conditions(especially emissivity changed). Based on the analyzed infrared signal, the optimized surface emissivity was suggested to reduce the average contrast radiance and contrast radiant intensity(CRI). In addition, we confirmed that the infrared contrast radiant intensity between the aircraft and the background can be minimized through an appropriately controlled surface emissivity of the aircraft at specific background.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.4
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• pp.463-470
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• 2014

Stealth technology of combat aircraft is most significant capability in recent air battlefield. As the detector of IR missiles is being developed, IR stealth capability which is evaluated by IR signature level become more important than it was in previous generation. Among IR signature of aircraft from various sources, aerodynamic heating dominates in long-wavelength IR spectrum of $8{\sim}12{\mu}m$. Skin temperature change by aerodynamic heating which is derived by effects of Mach number and structure. The 4th and 5th generation aircraft are selected for calculation of the skin temperature, and its height and velocity in numerical conditions are 10,000 m and Ma 0.9~1.9 respectively. Aircraft skin temperature is calculated by computing convection of fluid and conduction, convection and radiation of surface. As the aircraft accelerates to higher Mach number, maximum skin temperature increases more rapidly than average temperature and temperature distribution changes in more sharp, interactive ways. The 4th generation aircraft whose shape is more complex than that of the 5th generation aircraft have complicated temperature distribution. On the other hand, the 5th generation aircraft whose shape is relatively simple shows plain temperature distribution and lower skin temperature in terms of both average and maximum value.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.8
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• pp.1110-1116
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• 2021

In this paper, we propose a conformal Ku-band data link antenna to ensure low RCS of stealth UAV. As a phased array antenna with electrical beam steering function, a transmitter and a receiver were designed and manufactured for FDD communication, respectively. Each antenna is designed as a 12*12 planar array antenna and has a function to form a uni-directional pattern and a bi-directional pattern through phase control of unit elements. The beam steering range is designed to be able to steer up to 60 degrees in theta direction and 360 degrees in the phi direction. As a result of manufacturing and measurement, the conformal type radome has low transmission loss and meets the required specifications including system performance. The feasibility of mounting the stealth UAV has been confirmed, and future research directions such as interworking of baseband devices and conversion to digital beam steering function are suggested.

• Defense and Technology
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• no.6 s.160
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• pp.40-47
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• 1992

전파흡수체의 응용분야는 사용목적에 따라 민수용과 군수용으로 크게 대별된다 민수용으로는 통신기기의 발달로 인하여 최근에 가장 문제가 되고 있는 전자파 장애(EMI) 대책용으로 사용되며 군수용으로는 무기체계의 생존성 향상(스텔스)으로 사용된다 여기서는 군수용에 초점을 두어 대표적인 응용 예를 살펴보았다

• Defense and Technology
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• no.8 s.174
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• pp.36-43
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• 1993

신예 항공기들은 고가의 무기와 첨단전자장비들을 갖추고 있기 때문에 가격 또한 엄청나게 비쌉니다. 따라서 전투시에 상대의 후방까지 깊숙하게 침투시에 상대의 후방까지 깊숙하게 침투하여 목표물을 공격하되, 아군 항공기의 손실은 최소로 줄이는 것이 승패를 좌우하는 매우 중요한 요소입니다 따라서 항공기의 생존성을 제고하기 위해서는 상대의 레이다에 포착되지 않는 은폐기술 즉, 스텔스(stealth)성능이 필수적입니다

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1519-1520
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• 2011

• International Journal of Aeronautical and Space Sciences
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• v.17 no.1
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• pp.20-28
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• 2016

In this study, an efficient method of designing laminate composite radar absorbing structures (RAS) is proposed with consideration given to the structural shape so as to improve aircraft stealth performance. The calculation of the radar cross section (RCS) should be decreased to enhance the efficiency of the stochastic optimization when designing an RAS. In the proposed method, RAS are optimized to match up the input impedance of the minimal RCS, which is obtained by using physical optics and the transmission line theory. Single and double layer dielectric RAS for aircraft wings are employed as numerical examples and designed using the proposed method, RCS minimization and reflection coefficient minimization. The availability of the proposed method is assessed by comparing the similarity of the results and computation time with other design methods. According to the results, the proposed method produces the same results as the stochastic optimization, which adopts the RCS as the objective function, and can improve RAS design efficiency by reducing the number of RCS analyses.