• 제목/요약/키워드: Stealth Technology

검색결과 84건 처리시간 0.033초

VitalBeam 선형가속기의 심부선량백분율과 측방선량분포 측정을 위한 새로운 기준 전리함으로서 스텔스 전리함의 성능 평가 (Performance Evaluation of Stealth Chamber as a Novel Reference Chamber for Measuring Percentage Depth Dose and Profile of VitalBeam Linear Accelerator)

  • 김연래;정진범;강성희;강상원;김경현;정재용;신영주;서태석;이정우
    • 대한방사선기술학회지:방사선기술과학
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    • 제41권3호
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    • pp.201-207
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    • 2018
  • The purpose of this study is to evaluate the performance of a "stealth chamber" as a novel reference chamber for measuring percentage depth dose (PDD) and profile of 6, 8 and 10 MV photon energies. The PDD curves and dose profiles with fields ranging from $3{\times}3$ to $25{\times}25cm^2$ were acquired from measurements by using the stealth chamber and CC 13 chamber as reference chamber. All measurements were performed with Varian VitalBeam linear accelerator. In order to assess the performance of stealth chamber, PDD curves and profiles measured with stealth chamber were compared with measurement data using CC13 chamber. For PPDs measured with both chambers, the dosimetric parameters such as $d_{max}$ (depth of maximum dose), $D_{50}$ (PDD at 50 mm depth), and $D_{100}$ (PDD at 100 mm depth) were analyzed. Moreover, root mean square error (RMSE) values for profiles at $d_{max}$ and 100 mm depth were evaluated. The measured PDDs and profiles between the stealth chamber and CC13 chamber as reference detector had almost comparable. For PDDs, the evaluated dosimetric parameters were observed small difference (<1%) for all energies and field sizes, except for $d_{max}$ less than 2 mm. In addition, the difference of RMSEs for profiles at $d_{max}$ and 100 mm depth was similar for both chambers. This study confirmed that the use of stealth chamber for measuring commission beam data is a feasible as reference chamber for fields ranging from $3{\times}3$ to $20{\times}20cm^2$. Furthermore, it has an advantage with respect to measurement of the small fields (less than $3{\times}3cm^2$ field) although not performed in this study.

알루미늄 스퍼터링 처리 의류소재의 스텔스 특성과 전자파 차단 및 전기적 특성에 관한 연구 - 밀도 변화를 중심으로 - (Stealth, electromagnetic interception, and electrical properties of aluminum sputtered clothing materials - Focusing on the density change -)

  • 한혜리
    • 복식문화연구
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    • 제30권4호
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    • pp.579-593
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    • 2022
  • This study examines the surface characteristics, electrical conductivity, electromagnetic wave blocking characteristics, infrared (IR) transmittance, stealth function, thermal characteristics, and moisture characteristics of IR thermal imaging cameras. Nylon film (NFi), nylon fabric (NFa), and 5 types of nylon mesh were selected as the base materials for aluminum sputtering, and aluminum sputtering was performed to study IR thermal imaging, color difference, temperature change, and so on, and the relationship with infrared transmittance was assessed. The electrical conductivity was measured and the aluminum-sputtered nylon film demonstrated 25.6kΩ of surface resistance and high electrical conductivity. In addition, the electromagnetic wave shielding characteristics of the sputtering-treated nylon film samples were noticeably increased as a result of aluminum sputtering treatment as measured by the electromagnetic wave blocking characteristics. When NFi and NFa samples with single-sided sputtering were placed on the human body (sputtering layer faced the outside air) and imaged using IR thermographic cameras, the sputtering layer displayed a color similar to the surroundings, showing a stealth effect. Moreover, the tighter the sample density, the better the stealth function. According to the L, a, b measurements, when the sputtering layer of NFi and NFa samples faced the outside air, the value of a was generally high, thereby demonstrating a concealing effect, and the △E value was also high at 124.2 and 93.9, revealing a significant difference between the treated and untreated samples. This research may be applicable to various fields, such as the military wear, conductive sensors, electromagnetic wave shielding film, and others.

무인전투기 배기구 형상에 따른 유동 및 적외선 신호 특성 분석 (Analysis of Flow and Infrared Signature Characteristics according to UCAV Nozzle Shape)

  • 노수영;배지열;김지혁;남주영;조하나;조형희
    • 한국추진공학회지
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    • 제23권5호
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    • pp.27-35
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    • 2019
  • 스텔스 기술은 레이더 및 적외선 시커와 같은 탐지기로부터의 탐지를 피하는 기술이다. 특히 IR 미사일은 항공기 자체의 열을 감지하기 때문에 적외선 신호에 의한 탐지는 더욱 위협적이며 적외선 스텔스 기술은 항공기 및 UCAV(Unmanned Combat Aerial Vehicle)의 생존을 보장하는데 필수적이다. 본 연구에서는 UCAV 노즐 설계에 따른 공력 및 적외선 스텔스 성능 분석이 수행되었다. 수치해석 결과에 따르면 Double S형 노즐은 엔진의 고온부를 차폐할 수 있기 때문에 적외선 신호를 줄이는 데 효과적이다. 또한, Double S형 노즐에서 회전부 위치가 뒤쪽에 위치할수록 적외선 신호가 감소함을 확인하였다.

항공기 형상에 대한 근전계 RCS 측정에서 내삽 알고리즘을 이용한 측정시간 단축에 대한 분석 (An Analysis on the Reduction of Measurement Time Using Interpolation Algorithm in Near-field RCS Measurements for Aircraft Shape)

  • 박호민
    • 한국군사과학기술학회지
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    • 제25권4호
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    • pp.339-346
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    • 2022
  • The importance of stealth technology is increasing in modern warfare, and Radar Cross Section(RCS) is widely used as an indicator of stealth technology. It is useful to measure RCS using an image-based near-field to far-field transformation algorithm in short-range monostatic conditions. However, the near-field measurement system requires a longer measurement time compared to other methods. In this work, it is proposed to reduce the measured data using an interpolation method in azimuth angular domain. The calculated far-field RCS values according to the sampling rate is shown, and the performance of the algorithm applied with interpolation in the angular domain is presented. It is shown that measurement samples can be reduced several times by using the redundancy in the angular domain while producing results similar to the conventional method.

소형 터보젯 엔진 후류의 측정 각도 별 적외선 신호 특성 (Infrared Signal Characteristics of Small Turbojet Engine Plume by Observation Angle)

  • 최재원;장현식;김혜민;최성만
    • 한국추진공학회지
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    • 제25권4호
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    • pp.28-35
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    • 2021
  • 열 추적 미사일로부터 항공기를 보호하기 위한 적외선(IR: InfraRed) 스텔스 기술은 군용 항공기 개발에 있어 매우 중요한 요소이다. 본 연구에서는 항공기에서 발생하는 다양한 적외선 신호 중 엔진 후류에서 발생하는 적외선 신호를 관측하고 이를 측정 각도별로 확인하여 신호 강도를 비교하였다. 실제 항공기에 적용된 제트 엔진을 모사하기 위해 소형 터보젯 엔진을 구성하였으며, 측정 각도에 따른 파장별 적외선 신호 특성을 확인하였고 파장별 신호를 적분하여 측정 범위 내 전체 적외선 radiance를 도출하였다. 본 연구를 통해 항공기 적외선 스텔스 성능 향상을 위한 기초 데이터를 제시하고자 한다.

공대공 적외선 미사일의 항력을 고려한 초음속 항공기의 피격성 분석 (Susceptibility Analysis of Supersonic Aircraft Considering Drag Force of Infrared Guided Missile)

  • 김태일;김태환;이환성;배지열;정대윤;조형희
    • 한국군사과학기술학회지
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    • 제20권2호
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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.

M&S 기반 함정음향 시험평가 개념 (A Concept on the M&S-based T&E for Ship Acoustics)

  • 조창봉
    • 한국군사과학기술학회지
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    • 제7권1호
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    • pp.24-33
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    • 2004
  • Recently, ship acoustics takes more important role in acoustic stealth and classification of underwater targets. In this paper, a theoretical concept is proposed for M&S-based test and evaluation of ship acoustics. The concept is based on two different approaches: on Top-Down method which emphasizes the survivability of the ship and on Bottom-Up method which considers acoustic characteristics of the ship-equipments. In order to improve the effectiveness of M&S-based T&E for ship acoustics, it is recommended in this paper to compromise the two approaches as adequate.

Conceptual design and RCS property research of three-surface strike fighter

  • Yue, Kuizhi;Tian, Yifeng;Liu, Hu;Han, Wei
    • International Journal of Aeronautical and Space Sciences
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    • 제15권3호
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    • pp.309-319
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    • 2014
  • This paper mainly focuses on the conceptual design and stealth performance of the three-surface military aircraft. A three-dimensional (3-D) digital mock-up of the three-surface strike fighter with stealth feature was designed and the schemes of carrying missiles were analyzed in CATIA. Based on physical optics principle and the Method of Equivalent Currents (MEC), a numerical simulation of the RCS feature of the aircraft was carried out with RCSPlus which is a software designed by Beihang University. The paper contributes to the RCS feature analysis of the whole plane and different parts on X-band, S-band and UHF-band and a comparison of RCS feature to Su-37 and T-50 military aircraft is drawn. On X-band, the pitch angle of the incident wave was $0^{\circ}$, and the result shows: (1) Compared with Su-37 aircraft, the forward scattering RCS of the three-surface strike aircraft was reduced to 14.9%, the side scattering RCS to 9.6% and the back scattering RCS to 40.2%. (2) Compared with T-50 aircraft, the forward scattering RCS was reduced to 38.61%, and the side scattering RCS to 67.26%. This paper should be useful for researchers in conceptual design and stealth technology of the military aircraft.