• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 12th Asian Congress of Fluid Mechanics
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• pp.73.3-73.3
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• 2008

• 한국군사과학기술학회지
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• 제17권4호
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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.

• 한국군사과학기술학회지
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• 제23권6호
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• pp.602-608
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• 2020

PRAIRIE(Propeller Air Induced Emission) system is a kind of underwater radiated noise suppression systems to reduce the probability of the identification or classification of our warship's acoustic signature by an enemy ship. It is effective in case of strong cavitation events. This is because air bubbles emitted from the PRAIRIE system mitigate drastic collapses of the cavity bubbles that can generate an intense shock wave. However, when the PRAIRIE system is operated in a non or weak cavitation condition, it might increase the total level of underwater radiated noise and induce the acoustic signatures. Therefore, this paper presents the trial results on ventilation control of PRAIRIE to find a more efficient operation depend on the cavitation condition. Then, we show a variation of the amplitude modulation characteristics according to ventilation control.

• 한국군사과학기술학회지
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• 제15권4호
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• pp.417-423
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• 2012

Radar Cross Section(RCS) is a measure of how detectable an object is with a radar. A larger RCS indicates that an object is more easily detected. Informally, the RCS of an object is the cross-sectional area of a perfectly reflecting sphere that would produce the same amount of reflection strength as the object in question would. In order to estimate RCS of aircraft weapons the external surface is modeled as a collection of simple shape elements. And the overall RCS is estimated as a vector sum of configuring elements' cross-sections which are well known given by analytic formulae. A RCS estimation code is developed for a typical shape of Air-To-Surface bombs and missiles. Size of weapons and location of fins are implemented in the code in addition to the presence of canards. The ability to predict radar return from flying vehicles becomes a critical technology issue in the development of stealth configurations. This simplified method of RCS estimation is known to be fast and accurate enough in an optical region of high frequency incident radio wave.

• 한국군사과학기술학회지
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• 제19권3호
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• pp.294-301
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• 2016

In this paper, we designed the transparent circuit analog radar absorbing structure using printed metal grid mesh for enhanced optical transmittance. To obtain wideband electromagnetic absorption and enhanced optical transparency at X-band, we proposed the resistive FSS(Frequency Selective Surface) using printed metal mesh pattern on transparent glass with PEC(Perfect Electric Conductor) plane using ITO(Indium Thin Oxide) coating. We then fabricated the proposed structure to verify the simulation results obtained from commercial EM simulator. The comparisons between the simulation and measured results show good agreements. The results also show that the proposed radar absorbing structure can provide wideband reflection as well as better optical transparency. We can apply this proposed structure to the canopy of stealth aircraft and other stealth and security applications for visible transparency.

• 한국군사과학기술학회지
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• 제17권4호
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• pp.456-462
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• 2014

Infrared(IR) guided heat-seeking missiles uses IR emissions from aircraft to detect and track a target. Due to passive characteristic of the IR guidance, early detection of the missile is difficult and it is significant threat to aircraft survivability. Therefore, IR signature prediction of the aircraft is an important aspect of the stealth technology. In this study, we simulated IR signature of the aircraft in real atmospheric conditions. Aircraft surface temperature distribution was calculated by using RadthermIR code. Based on temperature distribution, IR radiance and BRDF(Bidirectional Reflectance Distribution Function) image were simulated for different weather(seasonal) and background(sky/soil) conditions. The IR contrast tendencies are not aligned with surface temperature or magnitude of target IR radiance. Therefore, it is essential to simulate IR signature with various conditions and background to acquire reliable database.

• 국방과기술
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• 6호통권160호
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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

• 국방과기술
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• 8호통권174호
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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

• 한국전산구조공학회논문집
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• 제29권5호
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• pp.455-461
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• 2016

적외선을 이용한 무기체계의 발달로 인해 항공기의 생존은 큰 위협에 직면해 있다. 따라서 항공기의 생존성 향상을 위해서 적외선 스텔스 기술이 매우 중요하다. 본 논문에서는 수치해석을 통해 실제 비행환경에서의 항공기 표면온도 및 주위 배경에 따른 적외선 신호를 분석하고 이를 바탕으로 적외선 스텔스를 위한 항공기 표면 구조체 방사율의 가이드라인을 제시하고 그 성능을 검증하고자 한다. 수치해석 결과, 주위 배경에 따라서 항공기 표면 방사율을 최적화한다면 항공기와 배경간의 복사대비강도를 감소시킬 수 있음을 확인하였다.

• Composites Research
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• 제35권1호
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• pp.13-17
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• 2022

입사된 전자파를 전자파를 흡수 및 산란시켜 산란시켜 레이더에 레이더에 포착을 포착을 막는 스텔스(Stealth) (Stealth) 기술이 등장 및 발전하였다. 스텔스 기술 중 하나인 전자파흡수구조(RAS)는 다기능성 복합재료로 복합재료로 하중지지 하중지지 및 전자파 전자파 흡수가 가능한 가능한 구조이다. 기존 전자파흡수구조들의 단점들을 보완하기 위해 단탄소 섬유층이 삽입된 형태의 하이브리드 전자파흡수구조가 제안되었다. 그러나 삽입된 단탄소 섬유층이 구조의 기계적 특성에 영향을 미칠 수 있다, 따라서 본 연구는 단탄소 섬유층이 삽입된 하이브리드 전자파흡수구조의 층간전단강도(ILSS)를 측정하였다. 단탄소 섬유층의 면적 밀도의 변화가 구조의 층간전단강도에 끼치는 영향을 알아보기 위해 단탄소 섬유층의 면적밀도가 다른 하이브리드 복합재료의 층간전단강도를 측정하였으며 총 4가지의 하이브리드 전자파흡수구조의 층간전단강도를 측정하여 glass/epoxy와 비교하였다. 측정 결과 단탄소 섬유층이 하이브리드 복합재료 및 전자파흡수구조의 층간전단강도에 큰 영향을 미치지 않음을 확인하였다.