• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.1
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• pp.81-92
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• 2019

Stealth means the reduction of all signature including the reflection/emission of radar, infrared, visible light and audio signals. Stealth aircraft can significantly improve the penetration capability, the combat survivability and the mission effectiveness. This paper presents the basic concept, the key elements and the application examples of stealth aircraft technology. Also it briefly describes the effect of the modern stealth aircraft on the future air warfare.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.1
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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.

• 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.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.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.6
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• pp.767-773
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• 2017

Infrared stealth is an important technology for naval ships. This technology helps improve the anti-detection performance and survivability of naval ships. In general, the infrared signature of naval ships are categorized into internal and external heat source. External signature are generated by ship surface heating by solar flux as well as the complicated heat transfer process with the surrounding weather condition. Modern naval ships are equipped with seawater injection nozzles on the outside for nuclear, biological and, chemical, and these nozzles are used to control external signature. Wide nozzle placement intervals and insufficient injection pressure, however, have reduced seawater dispersion area. To address this problem, nozzle installation standards must be established. In this study, an actual-scale experimental system was implemented to provide the evidence for nozzle installation standards in order to reduce the infrared signature of naval ships. In addition, the environmental conditions of the experiment were set up through computational fluid dynamics considering the ocean climate data and naval ship management conditions of South Korea. The dispersion distance was measured using a high-resolution thermography system. The flow rate, pipe pressure, and dispersion distance were analyzed, and the evidence for the installation of seawater injection nozzles and operation performance standards was suggested.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.4
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• pp.1-6
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• 2005

The ability to predict radar return from flying vehicles becomes a critical technology issue in the development of stealth configurations. Toward developing a CEM code based on Maxwell's equations for analysis of RCS reduction schemes, an explicit upwind scheme suitable for multidisciplinary design is presented. The DFFT algorithm is utilized to convert the time-domain field values to the frequency-domain. A Green's function based on near field-to-far field transformation is also employed to calculate the bistatic RCS. To verify the numerical calculation the two-dimensional field around a perfectly conducting cylinder is considered. Finally results are obtained for the scattering electromagnetic field around an airfoil in order to illustrate the feasibility of applying CFD based methods to CEM.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.2
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• pp.87-94
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• 2023

As the latest weapon systems and electronic equipments are increasingly demanding stealth technology to improve the survivability of allies, it is necessary to implement low-observability technology that reduces the radar cross section(RCS). In order to implement this stealth technology, a method for low RCS characteristics by applying a shape design or a electromagnetic wave absorber is widely used. However, active phased array antennas have structural limitations in shape design, also when a absorber is applied to it, the performance of the antenna is degraded. Therefore, in this paper, in order to realize the low RCS characteristics of the active phased array antenna operating in the X-band, individual radiating elements suitable for applying the radio wave absorber were selected, and a 13x13 array antenna was designed and manufactured. Next, by comparing the measured results of the relative RCS and electrical performance for the manufactured antenna according to the presence and type of the absorber, it is shown that the electrical performance is maintained at an equal or higher level while obtaining the low RCS characteristics. Thereby the method proposed in this paper for implementing the low RCS characteristics was validated. Finally, it was confirmed that when the wave absorber is applied to the array antenna, the limitation of its performance deterioration can be overcome.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.2
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• pp.171-175
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• 2017

The high-tech large warships are minimal and they are always monitored by opponents, and become primary targets when conflicts occur. The improvement in reducing susceptibility has significant importance because it is difficult for a ship to maintain mission capability and functionality once it is damaged. Ordinary decoys are effective only under the premise that the ship has already been exposed. Traditionally, for naval vessels, techniques related to the radar have been used in military stealth techniques to ensure confidentiality. The corner reflector, on the other hand, can produce rather large radar cross sections. Continued use of deceptive systems such as chaff during operations will help to improve survivability of naval ships. From this viewpoint, corner reflector was considered for making radar countermeasures and deception technology. This paper reviews the current status of corner reflector basis decoys and the technical feasibility of corner reflectors for developing structural decoys.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.11
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• pp.2206-2212
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• 2017

When it comes to naval surface warfare, the probability of detection is an important factor in survivability and the Radar Cross Section(RCS) is a major parameter. In this paper, the RCS reduction technology of the Radar Absorbing Material(RAM) method is carried out for the general frequency range for naval warfare. We set the analysis model with the simplified ship model and the wide band metamaterial which is high-tech radar absorbing materials is selected for the RAM method. The modeling of the wide band metamaterial composed of an MIK surface which has the wide band resonant properties and flexible substance and the electromagnetic absorptions and reflections of the wide band metamaterial has been simulated to explore the performance. Also, the wide band metamaterial is compared with the paint absorber to analyze RCS reduction in terms of RCS values.

• Composites Research
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• v.23 no.2
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• pp.17-23
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• 2010

The stealth technology can increase the survivability of aircrafts or warships and enhance the capability of mission completion in hostile territory. The purpose of this paper is to present the low observable structure with curved surfaces made by fiber-reinforced composites and to show the possibility of developing omnidirectional stealth platforms for military applications. In this study, we developed a radar absorbing structures(RAS) based on a circuit analog absorber to reduce the radar cross section(RCS) of an object with curved surfaces. Firstly, the RAS with a periodic square patterned conducting polymer layer was designed and simulated using a commercial 3-D electromagnetic field analysis program. Secondly, the designed semi-cylindrical structure with low RCS was fabricated using fiber-reinforced composites and conducting polymer. To make the periodic pattern layer, acts as resistive sheet, the intrinsic conducting polymer paste containing PEDOT with a polyurethane binder was used. Finally, the radar cross section was measured to evaluate the radar absorbing performances of the fabricated RAS by the compact range facility in POSTECH.