• Journal of Ocean Engineering and Technology
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• v.24 no.3
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• pp.38-45
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• 2010

A study on the infrared signature of a naval ship by the solar elevation was performed using the well known IR signature analysis software, ShipIR/NTCS. The contrast radiant intensity of a ship against the Eastern Sea background from sunrise to noon was investigated. Monthly averaged climate data for both January and July were applied to investigate the seasonal change in the signature. A study on the signature for different ship speeds was also carried out. Simulation results showed that the maximum signature in both wave-bands for a sea-level observer occurred at around 25~35 degrees of solar elevation and was highly dependent on the ship geometry rather than the solar irradiance.

• Journal of Ocean Engineering and Technology
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• v.27 no.3
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• pp.36-42
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• 2013

According to a study on improving ship survivability, an IR signature represents the contrast radiance intensity between the radiation signature from a ship and the background signature. It was found from applying stealth techniques to the process of ship development that the IR signature is remarkably sensitive and dependent on the environment. In this study, marine climate data for the sea near the Korean Peninsula were collected, and the marine meteorological environment in Korean waters was defined. Based on this data, a study on the sensitivity of the IR signature of target objects was performed using analytical methods. The results of the research indicated that clouds have important effects on the infrared signature, but the velocity of the wind and the humidity have only slight effects on the IR signature. In addition, the air and seawater temperatures had hardly any effect on the IR signature, but it is judged that additional study is needed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.7
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• pp.568-575
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• 2016

For the combat survivability, an infrared signature emitted from aircraft is needed to be predicted and analyzed. In this study, we studied the infrared signature from the exhaust plume from the viewpoint of Infrared(IR) detector. The Line-By-Line method using the radiation database is used for radiative property, and radiative intensity analysis is conducted along 1-D line of sight based on the radiative property. The numerical thermo-fluid field for the plume is conducted by ANSYS FLUENT, while setting the lines of sight having the different detection angle on the thermo-fluid field. We found the high IR signature on the line of sight passing through the locally high temperature region of the plume inside, and the strongest signature from the line of sight toward the nozzle surface. Based on this, it confirms the influence of the surface radiative emission on the infrared signature.

• Journal of the Society of Naval Architects of Korea
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• v.50 no.3
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• pp.182-189
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• 2013

In the development process of new naval ships, it is necessary to make the effort of the signature management and reduction of ship infrared(IR) signature to increase the ship survivability(susceptibility). So far the ship's contrast radiant intensity is used as a ship IR signature design criteria during the naval ship design stages. However, nowaday it is in a state of disorder at the basic design stage because of the lack of any related studies and methods. In this study, the IR signature management methods for improving the signature reduction and ship survivability are suggested by the comparison analysis of the advantages and disadvantages of signature management techniques. And also the criteria for the ship signature management are suggested when considering the infrared signature measuring assets and sea trial environments of the Korean peninsula.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.10
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• pp.779-787
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• 2013

The effects of various nozzle configurations on infrared signature are investigated for the purpose of analysing the infrared signature level of aircraft propulsion system. A virtual subsonic aircraft is selected and then a circular convergent nozzle, which meets the mission requirements, is designed. Convergent nozzles of different configurations are designed with different geometric profiles. Using a compressible Navier-Stokes-Fourier CFD code, an analysis of thermal flow field and nozzle surface temperature distribution is conducted. From the information of plume flow field and nozzle surface temperature distribution, IR signature of plume and nozzle surface is calculated through the narrow-band model and the RadThermIR code. Finally, qualitative information for IR signature reduction is obtained through the analysis of the effects of various nozzle configurations on IR signature.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.8
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• pp.688-694
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• 2012

A study on the effect of engine nozzle configuration on the engine plume Infra-red (IR) signature characteristics is performed. Configuration design of an engine nozzle with high aspect ratio to reduce IR signature level and a cylindrical nozzle which is typically used for conventional aircraft which does not require IR signature reduction is performed. And CFD analysis for the two nozzles is performed to compare the flowfields characteristics of the two nozzles. Finally IR signature analysis for the two nozzles is accomplished to calculate the total intensity level at mid-wave infra-red and investigate the differences of IR signature characteristics between the two nozzles.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.596-597
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• 2017

In this study, the measurements of infrared (IR) signature were carried out using a small scale engine with the variation of the engine performance and target positions in the exhaust plume. The operating conditions of the engine were kept constant for each test, and the measured positions were sapced at refular intervals from the nozzle exit. The measured IR signature was calibrated by using a blackbody. The results of infrared signature measurements are shown in three bands for analysis of spectral characteristics. As the engine performance decreased and the distance from the nozzle exit increased, the IR signature decreased and the level of decrease varied according to the bands.

• 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.13 no.2
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• pp.320-327
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• 2010

The IR signature data of a ship is mainly affected by location, meteorological conditions(atmosphere temperature, wind direction and velocity, humidity etc.), atmospheric transmittance, solar position and ship surface temperature etc. The IR signatures received by a remote sensor at a given temperature and wavelength region is consisted of the self-emitted component directly from the object surface, the reflected component of the solar irradiation at the object surface, and the scattered component by the atmosphere without ever reaching the object surface. Computer simulations for prediction of the IR signatures of ships are very useful to examine the effects of various sensor positions. In this paper, we have acquired the IR signature for different sensor positions by using computer program for prediction of the IR signatures. The numerical results show that the IR signature contrast as compared to the background sea considering the meteorological conditions, solar and sky irradiations.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.6 s.144
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• pp.679-685
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• 2005

Until now, the stealth design to reduce the infrared signature of ship haven't been carried out using the proper design criteria. The study on the maritime meteorological environment in the Korean seas hasn't been accomplished yet, so the design criteria of the maritime meteorological environment was just given by the engineering sense without experience of the Navy and/or of the shipyard. Even in rather good conditions(summer condition), the estimated IR signature of a ship showed larger values and couldn't predict the worst condition during the operation of a ship at sea. In this study, domestic maritime meteorological data were collected and variables affecting the IR signature of a ship had been derived through the sensitivity study of IR signature according to the maritime meteorological environment in Korean seas. The basic study on the criteria of the stealth design of IR signature has been carried out.