• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.3
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• pp.204-212
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• 2015

The infrared lock-on range of target aircraft plays a critical role in determining the aircraft survivability. In this investigation, the effects of various UAV engine nozzle configurations on the aircraft lock-on range were theoretically analyzed. A virtual subsonic aircraft was proposed first, based on the mission requirement and the engine performance analysis, and convergent-type nozzles were then designed. After determining thermal flow field and nozzle surface temperature distribution with the CFD code, an additional analysis was conducted to predict the IR signature. Also, atmospheric transmissivity for various latitude and seasons was calculated, using the LOWTRAN code. Finally, the lock-on and lethal envelopes were calculated for different nozzle configurations, assuming the sensor threshold of the given IR guided missile. It was shown that the maximum 55.3% reduction in lock-on range is possible for deformed nozzles with the high aspect ratio.

• Journal of Satellite, Information and Communications
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• v.12 no.4
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• pp.78-86
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• 2017

Japan has a lot of interest about weapons systems development of surrounding national and has invested heavily in securing intelligence assets to get information about them, because of conflict issues between Japan and Russia with four northern islands, China with Senkaku Islands and entry policy into the Pacific. Japan has used a large budget to detect and intercept ballistic missile for reasons of the launch of the Taepodong missile in 1998. After took over SIGINT equipments which U.S. force had operated in 1950s~1960s, Japan made a technological analysis and advanced IT technology to produce superior equipments. Japan's SDF has installed them in 19 locations across Japan. In addition, Japan's JASDF has installed advanced early warning RADAR to detect aircraft and high speed ballistic missile entering JADIZ with S-band in 28 locations across Japan. It is possible to detect missile launch preparations, engine tests, and launch moments at any time for operation of 6 satellites high resolution reconnaissance system and 6 aegis ships. In close cooperation with the US, Japan is accessible to the SBIRS networks which detects the launch of a ballistic missile in neighboring countries. In the future, Because the United States wants Japan to act as part of the United States in East, south Asia, it is believed that the exchange of intelligence on the surrounding countries between two countries will be enhanced.

• Computers and Concrete
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• v.5 no.6
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• pp.509-524
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• 2008

Containment structures not only are leak-tight barriers, but also may be subjected to impacts caused by tornado-generated projectiles, aircraft crashes or the fragments of missile warhead. This paper presents the results of an experimental study of the impact resistance of steel fiber-reinforced concrete against 45 g projectiles at velocity around 2500 m/s. An explosively formed projectile (EFP) was designed to generate an equivalent missile fragment. The formation and velocity of EFP are measured by flash x-ray. A switch made of double-layered thin copper sheets controlled the exposure time of each flash x-ray. The influence of the fiber volume fraction on the crater diameter of concrete slab and the residual velocity of the projectile were studied. The residual velocity of the projectile decreased as the fiber volume fractions increased. In this work, the residual velocity of the projectile was to 44% that of plain concrete when the fiber volume fraction exceeded 1.5%. Based on the present finding, steel fiber reinforced concrete with the fiber volume fraction exceeding 1.5% appear to be more efficient in protection against high velocity fragment impact.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.1
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• pp.79-88
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• 2001

The target such as aircraft operates flares to protect itself from the missile. In general, Infra-red(IR) flares that are hot bodies radiating energy considerably greater than it does, so cause the missile to guide the flare instead of the target. For a precise target tracking in spite of a presence of flares, therefore, the seeker should discriminate the target signal from various clutters including the flare and the background. In this paper, we simulated 2-color rosette scan seeker using IR and UV(UltraViolet) bands. In each wave band, we analyzed the radiant distributions of the target, the flare, and background. These results showed that a simultaneous process in two bands can detect precisely the target.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.4
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• pp.106-112
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• 2021

In the early 1960s, US Air Force lost missile launch bases during ICBM development by a defect in the missile design and operation plan. U.S. DoD realized the limitation of the existing accident prevention method. Therefore, the weapon development required system safety activity, and procurement projects of U.S. DoD applied MIL-STD-882(System Safety). Development projects of U.S. DoD more emphasized the importance of system safety after the space shuttle Challenger exploded in 1986. Currently, Airworthiness certification for military aircraft uses system safety to minimize accidents. The domestic defense aviation R&D projects also use the system safety for the airworthiness certification. However, non-aviation weapon R&D projects rarely applied system safety. This paper presents a system safety application method for domestic weapon R&D projects by studying the U.S. military standards/organizations and domestic defense aviation projects.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.5
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• pp.359-365
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• 2022

Air-to-ground missile(AGM), which can be operated by being mounted on the outside of the aircraft, is capable of precision strikes, ensuring high survivability. Helicopter, which is one of the AGM operating platforms, is reported to experience a lightning strike once between 1000 and 20000 flight hours in average. When the lightning strikes the helicopter fuselage, lightning transient signal can be induced to internal and external electronic equipment cables through the skin of the helicopter. If the transient signal exceeding the criteria to electrically initiated device(EID) related to the explosive in the AGM can affect the safety of the helicopter by a warhead explosion, etc. In this paper, we suggest an indirect lightning test method to prove the safety of AGM on helicopter, and present the indirect lightning test results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.12
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• pp.1084-1093
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• 2017

As the survivability of an aircraft in the battlefield becomes a critical issue, there is a growing need to improve the survivability of the aircraft. In this study, the survivability of an UCAV associated with plume IR signature was investigated. In order to analyze the survivability of the aircraft, the lock-on range and the lethal envelope, defined as the IR detection distance of the aircraft and the range of shooting down by the missile, respectively, were first introduced. Further, a method to calculate the lethal envelope for the scenario of surface-to-air missiles including the vertical plane was developed. The study confirmed that the red zone of an UCAV shows a substantial difference in the zone size as well as the characteristics in the upward and downward directions.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.463-467
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• 2005

In this paper, the guidance law applicable to formation flight of UAV in three-dimensional space is proposed. The concept of miss distance, which is commonly used in the missile guidance laws, and Lyapunov stability theorem are effectively combined to obtain the guidance commands of the wingmen. The propose guidance law is easily integrated into the existing flight control system because the guidance commands are given in terms of velocity, flight path angle and heading angle to form the prescribed formation. In this guidance law, communication is required between the leader and the wingmen to achieve autonomous formation. The wingmen are only required the current position and velocity information of the leader vehicle. The performance of the proposed guidance law is evaluated using the complete nonlinear 6-DOF aircraft system. This system is integrated with nonlinear aerodynamic and engine characteristics, actuator servo limitations for control surfaces, various stability and control augmentation system, and autopilots. From the nonlinear simulation results, the new guidance law for formation flight shows that the vehicles involved in formation flight are perfectly formed the prescribed formation satisfying the several constraints such as final velocity, flight path angle, and heading angle.

• Advances in aircraft and spacecraft science
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• v.4 no.1
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• pp.37-52
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• 2017

Gas turbines operating in dusty or sandy environment polluted with micron-sized solid particles are highly prone to blade surface erosion damage in compressor stages and molten sand attack in the hot-sections of turbine stages. Commercial/Military fixed-wing aircraft engines and helicopter engines often have to operate over sandy terrains in the middle eastern countries or in volcanic zones; on the other hand gas turbines in marine applications are subjected to salt spray, while the coal-burning industrial power generation turbines are subjected to fly-ash. The presence of solid particles in the working fluid medium has an adverse effect on the durability of these engines as well as performance. Typical turbine blade damages include blade coating wear, sand glazing, Calcia-Magnesia-Alumina-Silicate (CMAS) attack, oxidation, plugged cooling holes, all of which can cause rapid performance deterioration including loss of aircraft. The focus of this research work is to simulate particle-surface kinetic interaction on typical turbomachinery material targets using non-linear dynamic impact analysis. The objective of this research is to understand the interfacial kinetic behaviors that can provide insights into the physics of particle interactions and to enable leap ahead technologies in material choices and to develop sand-phobic thermal barrier coatings for turbine blades. This paper outlines the research efforts at the U.S Army Research Laboratory to come up with novel turbine blade multifunctional protective coatings that are sand-phobic, sand impact wear resistant, as well as have very low thermal conductivity for improved performance of future gas turbine engines. The research scope includes development of protective coatings for both nickel-based super alloys and ceramic matrix composites.

• The Korean Journal of Air & Space Law and Policy
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• v.26 no.2
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• pp.41-68
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• 2011

This article deals with the current rules of law of air warfare and its surrounding issues on precautionary action by a military aircraft at air-to-air operation in international armed conflict. However there is no separate and independent legal system to regulate warfare in aerospace in the current system of law of war (or law of armed conflict). In other words, law of air warfare does not exist in a form of a separate treaty. Air warfare has been regulated by international customary law and the relevant provisions in different Conventions, including 1949 four Geneva Conventions and two Additional Protocols, which mainly regulate land and naval warfare. And this makes difficult to make clear a legal term or legal tests on an issue concerned with law of air warfare, which concludes from time to time a dispute on interpretation and implementation of law of air warfare between states. Therefore, this article refers various materials (including 1949 Geneva Conventions and Additional Protocols, San Remo Manual, Harvard Manual, and ICAO Manual on Interception of Civilian Aircraft) for the purpose of defining the current and desirable legal test on precautionary action by military aircraft. In addition to the main purpose of this article, this article tried to show a characteristic of developing mechanism of law of air Warfare taking into account interactions between international air law and law of air warfare.