• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.5
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• pp.373-382
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• 2013

In this paper, in order to analyze the performance of a decoy system for ship defense against an anti-ship missile(ASM) with an infrared image(IIR) seeker, the modeling and engagement simulation program is introduced. The IIR seeker on the ASM detects the infrared signal of ship from a distance and approaches the ship based on proportional navigation guidance(PNG) or impact angle control guidance(IACG). Hence the guidance performance of the ASM is basically depend on the target tracking algorithm of the seeker as well as the infrared signal of the ship. Using the developed program, we can investigate the effect of the ship decoy system such as flares and surface cooling system of the ship with respect to various kinds of tracking algorithms of the IIR seeker of the ASM.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.103-110
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• 2018

Infrared signatures emitted from naval ships are mainly classified into internal signatures generated by the internal combustion engine of the ship and external signatures generated from the surface of the ship heated by solar heat. The internal signatures are also affected by the chemical components ($CO_2$, $H_2O$, CO and soot) of the exhaust plumes generated by the gas turbine and diesel engine, which constitute the main propulsion system. Therefore, in this study, the chemical composition ratios of the exhaust plumes generated by the gas turbines and diesel engines installed in domestic naval ships were examined to identify the chemical components and their levels. The influence of the chemical components of the exhaust plumes and their ratios on the infrared signatures of a naval ship was investigated using orthogonal arrays. The infrared signature intensity of the exhaust plumes calculated using infrared signature analysis software was converted to the signal-to-noise ratio to facilitate the analysis. The signature analysis showed that $CO_2$, soot and $H_2O$ are the major components influencing the mid-wave infrared signatures of both the gas turbine and diesel engine. In addition, it was confirmed that $H_2O$ and $CO_2$ are the major components influencing the long-wave infrared signatures.

• Journal of Korea Society of Industrial Information Systems
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• v.28 no.6
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• pp.21-27
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• 2023

Modern naval ships install an Infra-Red Signature Suppression system (IRSS) in their exhaust pipe to reduce infrared signature emitted to the outside. In addition, naval ships are strategic assets with a very long life cycle, so high reliability of the performance of the equipment on board must be guaranteed. Therefore, equipment such as IRSS is evaluated for performance through model testing at the design stage. A variety of measuring instruments are used in IRSS model testing, and the reliability of these instruments must also be guaranteed. In this paper, a study was conducted to evaluate the reliability of measurement equipment used in IRSS model testing. The test equipment and instruments used were a hot gas wind tunnel, pitot tube, digital differential pressure gauge, thermocouple sensor, and digital recorder. As the fan speed of the hot gas wind tunnel increased, the measurement deviation of the flow decreased, and the temperature output of the thermocouple sensor showed differences in response time and stability depending on the method used.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.740-746
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• 2017

Infrared signatures emitted from hot exhaust gases generated by the internal combustion engine and generator of naval ships and from the metal surfaces of the funnel have become the targets of infrared homing missiles, which is the main cause of a reduced survivability of naval ships. The infrared signatures from the exhaust gas and the metal surface of a funnel can be reduced by installing an infrared signature suppression (IRSS) system on a ship. The IRSS system consists of three parts: an eductor that generates turbulent flow of the exhaust gas, a mixing tube that mixes the exhaust gas with ambient air, and a diffuser that forms an air film using the pressure difference between the inside and outside air. As a basic study to develop an IRSS system using domestic technology, this study analyzed the model test conditions of an IRSS system developed by an overseas engineering company and installed on a domestic naval ship, and a numerical heat-flow analysis was conducted based on the results of the aforementioned analysis. Numerical heat-flow analysis was performed using a commercial numerical-analysis application, and various turbulence models were considered. As a result, the temperature and velocity of the exhaust gas at the educator inlet and diffuser outlet and that of the metal surface of the diffuser were measured, and found to agree well with the measurement results of the model test.

• Journal of Korea Society of Industrial Information Systems
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• v.23 no.2
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• pp.19-28
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• 2018

In this paper, we studied on the sampling of ocean meteorological data to analyze signature of naval ships. The newest ocean meteorological data, that was quality controled by the Korea Meteorological Administration(KMA), was collected. Outliers were removed from the data by setting the usable range of data. After that, the data size was reduced through the random sampling method, taking geopolitical significance and effective area of buoy, for probabilistic analysis. Moreover, the sample sizes were set at 100, 200, and 400 by considering the population size and a 95% confidence level. The final sample was obtained using the two-dimensional stratified sampling method based on highly correlated water temperature and air temperature. The sum of the squared errors and the confidence interval was calculated to compare the result of sampling. As a result, this study proposed reasonable sample size for infra­red signature analysis of naval ships.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.4
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• pp.459-465
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• 2007

This paper deals with the development of measuring methodology and the requirement for its evaluation of the infrared radiation from a naval ship to optical sensors, considering the Meteorological conditions. Factors required for measuring the apparent temperature and infrared radiation are identified and two methods are suggested based on the measuring instruments carried by ship or aircraft. and target operation in the Meteorological conditions is considered. This study describes some factors affecting the IR signature. required instruments to obtain the IR signal considering the naval ship.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.3
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• pp.264-272
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• 2012

A study on the IR(InfraRed) signature of a naval ship has been performed using well known IR signature analysis software, ShipIR/NTCS. Variations of the IR signature radiated from skins of a naval ship have been investigated according to the monthly averaged marine climate conditions. An unclassified destroyer model with and without applying the washdown system was applied to compare the influence on the signature under the background changes. The marine background models were created from the observed data by a buoy of Korea Meterological Administration(KMA). The sensitivity of the ship signature against the climate variables such as air temperature, sea temperature, relative humidity has been studied as well. The seasons which show extreme(max, min) skin signature change by whether the washdown is applied or not. The sensitivities of the air temperature and the sea temperature for a dry-ship reversed by applying the washdown on the ship surfaces.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.76-76
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• 2017

표면영상유속계는 홍수시 하천의 표면유속을 손쉽게 측정할 수 있는 매우 효율적인 장비이다. 특히 원적외선 카메라를 이용할 경우 주야간에 관계없이 사용할 수 있어, 그 유용성이 크게 높아진다. 다만, 원적외선 카메라는 그 특성상 해상도가 일반 비디오 카메라에 비해 현저하게 떨어지는 단점이 있다. 본 연구는 이러한 해상도가 낮은 원적외선 영상을 이용하여 보다 효율적으로 표면유속을 산정하는 새로운 기법을 구현하는 것이다. 해상도가 낮다는 것은 영상 내에 추적을 위한 추적자가 잘 나타나지 않는다는 의미이다. 이처럼 적절한 추적자가 영상내에 적을 경우에는 정확한 표면유속을 산정하기 곤란하다. 본 연구에서는 이 문제를 해결하기 위해 두 가지 방안을 조합하였다. 기존의 상호상관분석에서는 동영상의 연속된 프레임 두 매를 이용하였다. 본 연구에서는 연속된 여러 매의 프레임을 병합하여 한 매의 병합영상으로 만들고, 이러한 병합영상 두 매를 상호상관분석하는 방법을 개발하였다. 이 경우 영상을 병합하기 때문에 한 병합영상내에 충분한 수의 추적자가 들어올 가능성이 그만큼 높아지게 된다. 정확도 향상을 위한 두 번째 방안은, 돗수분포 평활화를 이용하는 것이다. 돗수분포 평활화 기법은 대비가 낮은 영상의 대비를 높이는 방법이다. 이렇게 대비를 높여서, 영상내 추적자의 존재를 더욱 확실하게 만들 수 있다. 이 두 가지 방법을 병용하여 새로 원적외선 표면영상유속계를 구현하고, 이를 기존의 분석이 어려웠던 동영상에 적용한 결과 그 분석 정확도가 현저하게 높아지는 것을 확인할 수 있었다.

• 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 Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.793-798
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• 2017

In modern naval ships, an infrared signature suppression (IRSS) system is used to reduce the metal surface temperature of the heated exhaust pipe and high-temperature exhaust gases generated from the propulsion system. Generally, the IRSS systems used in Korean naval ships consist of an eductor, mixing tube, and diffuser. The diffuser reduces the temperature of the metal surface by creating an air film due to a pressure difference between the internal gas and the external air. In this study, design variables were selected by analyzing the shapes of a diffuser designed by an advanced overseas engineering company. The characteristics of the design variables that affect the performance of the IRSS were investigated through the Taguchi experimental method. A heat flow analysis technique for IRSS systems established in previous studies was used analyze the performance of the diffuser. The performance evaluation was based on the area-averaged value of the metal surface temperature and exhaust gas temperature at the outlet of the diffuser, which are directly related to the intensity of the infrared signature. The results show that the temperature of the exhaust gas was significantly affected by changes in the diameter of the diffuser outlet, and the temperature of the diffuser's metal surface was significantly affected by changes in the number of diffuser rings.