• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.5
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• pp.484-488
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• 2010

Infrared emissivity is one of the most important factors for the temperature measurement by infrared thermography. Although the infrared emissivity of an object can be measured from the ratio of blackbody and the object, at room temperature it is practically difficult to measure the value due to the background effects. Hence, quantitative reflectance of bare steel plate and the surface of coating was measured by FT-IR spectroscopy and emissivity was calculated from this. The emissivity of polished bare steel surface was from 0.06 to 0.10 and the value for the unpolished bare steel can not be achieved because optical characteristics changes of surface roughness induces erroneous results. Emissivity of transparent paint coated steel was from 0.50 to 0.84. Depends on the IR absorption regions, which is a characteristic value of the coating, emissivity changes. This study suggests surface condition of material, thickness, roughness et cetra are important factor for IR optical characteristics. Emissivity measurement by reflection method is useful technique to be applied for metal and it with coating applied on the surface. The range of experimental errors of temperature can be narrowed by the application of infrared thermography from the measured thermal emissivity.

• Korean Journal of Optics and Photonics
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• v.35 no.5
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• pp.228-234
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• 2024

Modern infrared-guided weapons detect and destroy targets by seeking and tracking the infrared radiation emitted by the target. By covering the target with a material that has low infrared emissivity, the infrared signal can be reduced to evade tracking. However, this method is effective only when the target is hotter than the background. Since the temperature of the background varies significantly between day and night, target signals with low emissivity at night can be captured by the optical systems of guided weapons due to signal contrast, as they are smaller than the background signals. In this study, the optimal emissivity for implementing infrared stealth for ground targets is calculated based on the temperature and emissivity of the background, as well as the temperature of the target. The size of the signal received by the optical systems of guided weapons, the contrast value of the image, and the lock-on range were calculated for target signals that vary depending on the emissivity of the target. The effectiveness of the optimal emissivity was demonstrated by thermal imaging computer simulations using COMSOL Multiphysics software.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.191-195
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• 2003

우리는 황토 조명등을 제작하여 원 적외선 발생 실험을 하였다. 실험에는 백열전구 200W, 실내온도 21도, 습도 38%의 조건에서 열화상실험과 TF-IR(적외선 분광방사 측정장치)에 의한 원적외선 방사한도를 측정하였으며, 그 결과 방사율 0.914와 방사에너지 6.23$\times$$10^2$ (w/$m^2$.$\mu\textrm{m}$) 가 얻어졌다. 이와 같은 결과로 황토조명등에서 원적외선이 발생한 것을 확인하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.10a
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• pp.207-207
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• 2009

요업 소성로에서 내화재로 흡수된 에너지는 피가열물에 방사열로 작용하며, 이때 내화물의 방사율이 높을수록로내의 온도를 상승시켜 소비되는 연료가 절감된다. 따라서 내열성과 방사율이 높은 세라믹 내열도료를 개발하여 구성물의 결정 구조, 열적특성, 적외선 방사량 및 에너지 절감실험에 대한 데이터를 분석한 결과 높은 내열성과 적외선 방사량 증가에 따른 에너지 절감에 효과가 있음을 알 수 있었다.

• 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 Computational Structural Engineering Institute of Korea
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• v.30 no.2
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• pp.179-184
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• 2017

Due to rapid development of infrared guided weapon, survivability of armored vehicle is severely threatened. Hence, reduction of susceptibility by lowering infrared signature level is essential to enhance survivability of the vehicle. For this purpose, numerical analysis is conducted to analyze time and spatial characteristics of infrared signature of the vehicle when surface emissivity changes in this study. The analysis shows that the emissivity which produces minimum contrast radiant intensity is significantly altered by time and detecting position. Based on the result, it is concluded that the controlled structures which have different emissivity should be adopted at different region of the vehicle to effectively decrease infrared signature level.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.6
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• pp.375-382
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• 2020

Owing to the rapid development of infrared guided weapon systems, the threat to aircraft survivability is constantly increasing, and research on infrared stealth technologies are being conducted to ensure aircraft survival. In this study, we analyze the minimum infrared signature of an aircraft according to its flight altitude by considering the characteristics of infrared guided missiles, which detect the contrast signature between the aircraft and background. We conducted computational fluid dynamics simulations for the convective coefficient, and heat transfer simulations were performed considering convection, conduction, and radiation for flight conditions. Thus, we obtained the surface temperature distribution of the aircraft and analyzed the aircraft infrared signature based on the flow characteristics around it. Furthermore, the optimum emissivity for the minimum infrared signature was derived, and the effect of the infrared signature was analyzed when this optimum emissivity was applied to the fuselage surface for each flight condition.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.2
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• pp.109-116
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• 2019

Survivability of soldiers has been greatly threatened by the development of thermal observation device(TOD). Therefore, infrared, especially thermal, stealth technology is applied to combat suit to avoid detection from TOD. In this study, prior to the thermal camouflage performance evaluation of combat suit, thermal signature characteristic from clothed the human body was analyzed considering the realistic condition for human surface temperature compared to that from unclothed human body. To get the realistic surface temperature distribution of human, thermoregulation and multi-layer skin structure model is applied to the human model. Based on temperature distribution, surface diffuse radiance in thermal range is calculated and by assuming the background conditions, contrast radiance intensity(CRI) characteristic of human body is analyzed. By wearing clothing, the CRI between background and human body became reduced in low emissive background but in high emissive background, the contrast is much more prominent. Therefore, this issue should be considered in design process of thermal camouflage combat suit.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.7
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• pp.545-551
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• 2016

Surface temperature of supersonic wind tunnel model was measured using an infrared thermography technique. To measure the temperature quantitatively, various calibration techniques such as blackbody calibration which converts detected camera signal to temperature, distortion correction due to the camera lens and an imbalance of camera pose, and emissivity calibration which considers viewing angles to the model surface, were employed. Throughout the study, for the quantitative as well as qualitative surface temperature measurement, it was verified that the distortion correction must be considered even for the use of two-dimensional model in aerodynamics testing.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.3
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• pp.240-245
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• 2013

Each pixel of InfraRed(IR) sensor differently responds to IR light as time elapses or the sensor on/off operation is repeated. As a result, the quality of IR sensor image is deteriorated, and therefore NUC(Non-uniformity Correction) is periodically needed for IR sensor. In this paper, in order to perform NUC in the Satellite, on-board V-grooved blackbody is designed with a baffle so that the emissivity of black body is to be higher than 0.995 as well as the temperature deviation is less than $1^{\circ}C$ in the range of the infrared wave length from 3.3 to $5.2{\mu}m$. To check its performance, the emissivity and the surface temperature of the blackbody by TRT(Transfer Reference Thermometer) and IR Micrometer scanner are measured, respectively. From the results, black body design is verified and the uncertainty of NUC is estimated through the measurement results.