• 한국군사과학기술학회지
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• 제17권1호
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• pp.82-89
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• 2014

The damage in germanium (Ge) optical window irradiated by a near-infrared continuous wave (CW) laser was studied. Laser-induced heating and melting process were surveyed, and the specific laser power and the irradiance time to melt were estimated by numerical simulation. The experiments were also carried out to investigate the macro and micro structure change on Ge window. Results showed that the surface deformation was formed by melting and resolidification process, the damaged surface had a polycrystalline phase, and the transmittance as an optical performance factor in mid-infrared region was decreased. We confirmed that an abnormal polycrystalline phase and surface deformation effect such as hillock formation and roughness increase reduced the transmittance of Ge window and were the damage mechanism of CW laser induced damage on Ge window.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.554-556
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• 2005

Meteorological imager on the Multi-functional Transport Satellite (MTSAT-IR), which has been operating formally since 28 June 2005, was intercalibrated with a polar orbit satellite [Aqua Moderate Resolution Imaging Spectroradiometer (Aqua/MODIS)] as a well-calibrated instrument. The intercalibration method used in this study was developed by the Cooperative Institute for Meteorological Satellite Studies (CIMSS). This was done for the infrared window channels. The differences of MTSAT-IR and MODIS were are -0.26 K for $11\;\mu m-IR$ window channel, 0.40 K for $12\;\mu m-IR$, window channel, and -0.67 K for $6.7\;\mu m-water$ vapor channel.

• 센서학회지
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• 제24권4호
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• pp.264-269
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• 2015

An infrared (IR) bolometer measures the change of resistance by absorbing incident IR radiation and generates a signal as a function of the radiation intensity. Since a bolometer requires temperature stabilization and light filtering except for the infrared rays, it is essential for the device to be packaged meeting conditions that above mentioned. Minimization of heat loss is needed in order to stabilize temperature of bolometer. Heat loss by conduction or convection requires a medium, so the heat loss will be minimized if the medium is a vacuum. Therefore, vacuum packaging for bolometer is necessary. Another important element in bolometer packaging is germanium (Ge) window, which transmits IR radiation to heat the bolometer. To ensure a complete transmittance of IR light, anti-reflection (AR) coatings are deposited on both sides of the window. Although the transmittance of Ge window is high for IR rays, it is difficult to use frequently in low-price IR bolometer because of its high price. In this paper, we fabricated IR window by utilizing silicon (Si) substrate instead of Ge in order to reduce the cost of bolometer packaging. To enhance the IR transmittance through Si substrate, it is textured using Reactive Ion Etching (RIE). The texturing process of Si substrate is performed along with the change of experimental conditions such as gas ratio, pressure, etching time and RF power.

• ETRI Journal
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• 제35권1호
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• pp.80-88
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• 2013

A passive infrared or pyroelectric infrared (PIR) sensor is mainly used to sense the existence of moving objects in an indoor environment. However, in an outdoor environment, there are often outbreaks of false alarms from environmental changes and other sources. Therefore, it is difficult to provide reliable detection outdoors. In this paper, two algorithms are proposed to reduce false alarms and provide trustworthy quality to surveillance systems. We gather PIR signals outdoors, analyze the collected data, and extract the target features defined as window energy and alarm duration. Using these features, we model target and false alarms, from which we propose two target decision algorithms: window energy detection and alarm duration detection. Simulation results using real PIR signals show the performance of the proposed algorithms.

• 대한원격탐사학회지
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• 제11권1호
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• pp.31-45
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• 1995

The values of brightness temperature difference (BTD) between 11um and 12um infrared channels may reflect amounts of low-level water vapor and cloud types due to the different absorptivity for water vapor between two channels. A simple method of classifying cloud types at night was proposed. Two-dimensional histograms of brightness temperature of the 11um channel and the BTD between the split window data over subareas around characteristic clouds such as Cb(cumulonimbus), Ci(cirrus), and Sc(stratocumulus) was constructed. Cb, Ci and Sc can be classified by seleting appropriate thresholds in the two-dimensional histograms. And we can see amounts of low-level water vapor in clear area as well as cloud types in cloudy area in the BTD image. The map of cloud types and low-level water vapor generated by this method was compared with 850hPa and 1000hPa relative humidity(%) of numerical analysis data and nephanalysis chart. The comparisons showed reasonable agreement.

• 대한원격탐사학회지
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• 제24권4호
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• pp.309-324
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• 2008

Terra/Aqua MODIS의 적외관측 자료를 이용하여 동아시아 지역에서 물리적 방법과 split-window 방법으로 총가강수량을 산출하는 알고리즘을 개발하였다. 물리적 방법에서는 동아시아 지역에 대한 분석 예측 자료를 생산하는 RDAPS 자료를 알고리즘의 초기 추정치로 사용하였다. 이 과정에서 복사전달계산을 위해 빠르고 정확도가 높은 RTTOV-7 모델을 이용하였다. Split-window를 이용한 총가강수량 산출에서는 동아시아 지역의 라디오존데 관측자료를 훈련자료로 사용하여 밝기온도를 계산하였고, 이로부터 관측된 밝기온도로부터 총가강수량을 산출할 수 있는 회귀식을 도출하였다. 위의 두 알고리즘을 2004년 8월과 12월의 MODIS 적외 자료에 적용하여 산출한 결과를 해양에서는 DMSP SSM/I 결과와 육지에서는 라디오존데 관측 결과와 비교하여 검증하였고, 이를 바탕으로 총가강수량의 정확성에 영향을 미치는 요인과 산출과정에 중요한 물리과정을 분석하였다. 비교결과 RDAPS, MODIS, split-window 방법에 비해 물리적 방법을 이용한 총가강수량의 산출 정확성이 높은 것으로 나타났다. 그러나 물리적 방법은 초기 추정치에 따라 산출결과가 상이하게 나타나는 단점을 가지고 있는 것으로 파악되었다. 따라서 TIGR 자료와 같은 기후 평균값을 초기치로 적용함에 있어 주의가 요구된다. 이러한 원인으로 지표 부근의 수증기에 대한 정보 부족 등을 들 수 있다. 이러한 단점에도 불구하고 지표와 지형의 변화가 큰 한반도를 포함한 동아시아 지역에서는 물리적 방법에 의한 총가강수량 산출의 효율성이 큰 것으로 사료된다.

• 한국컴퓨터정보학회논문지
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• 제24권6호
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• pp.73-80
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• 2019

In this paper, we propose an effective dynamic range compression (DRC) method of infrared images. A histogram of infrared images has narrow dynamic range compared to visible images. Hence, it is important to apply the effective DRC algorithm for high performance of an infrared image analysis. The proposed algorithm for high dynamic range divides an infrared image into the overlapped blocks and calculates Shannon's entropy of overlapped blocks. After that, we classify each block according to the value of entropy and apply adaptive histogram modification method each overlapped block. We make an intensity mapping function through result of the adaptive histogram modification method which is using standard-deviation and maximum value of histogram of classified blocks. Lastly, in order to reduce block artifact, we apply hanning window to the overlapped blocks. In experimental result, the proposed method showed better performance of dynamic range compression compared to previous algorithms.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권3호
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• pp.1464-1480
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• 2019

Robust tracking of infrared (IR) pedestrian targets with various backgrounds, e.g. appearance changes, illumination variations, and background disturbances, is a great challenge in the infrared image processing field. In the paper, we address a new tracking method for IR pedestrian targets via multi-feature local sparse representation (SR), which consists of three important modules. In the first module, a multi-feature local SR model is constructed. Considering the characterization of infrared pedestrian targets, the gray and edge features are first extracted from all target templates, and then fused into the model learning process. In the second module, an effective tracker is proposed via the learned model. To improve the computational efficiency, a sliding window mechanism with multiple scales is first used to scan the current frame to sample the target candidates. Then, the candidates are recognized via sparse reconstruction residual analysis. In the third module, an adaptive dictionary update approach is designed to further improve the tracking performance. The results demonstrate that our method outperforms several classical methods for infrared pedestrian tracking.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(4)
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• pp.73-76
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• 2000

A Scene Based Technique(SBT) that corrects linear array infrared detector's nonuniformity is proposed. Basically, this technique dispenses with using temperature references on a linear array infrared detector. To correct the nonuniformity of infrared images, we use three methods. Firstly, we detect bad channels by using the information which is cumulated all the same line pixels. Secondly, a variable window method is applied to compensate more accurately. Thirdly, an adaptive method which updates gain and offset coefficient is used only on a stationary region. These results are demonstrated on a computer simulation with various images. As a result, the nonuniformity is corrected completely, so that images are enhanced and PSNR(peak signal to noise ratio) is improved much.

• 한국지능시스템학회논문지
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• 제21권2호
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• pp.260-267
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• 2011

본 논문은 GrabCut 알고리듬을 기반으로 적외선(infrared; IR) 영상에서 물체를 배경으로부터 분할하는 방법을 제안한다. GrabCut 알고리듬은 관심 있는 물체를 둘러싸는 윈도우가 필요하며, 이는 사용자가 설정한다. 그렇지만 이 알고리듬을 영상 시이퀀스에서 물체인식에 적용하려면 윈도우의 로케이션이 자동으로 결정되어야만 한다. 이를 위해서 본 논문에서는 Otsu 알고리듬으로 한 영상에서 관심은 있으나 알져지지 않는 물체를 적당히 분할하고 블랍 해석을 통해 윈도우를 자동으로 로케이션한다. 그랩 컷 일고리듬은 관심있는 물체와 배경의 확률분포를 추정해야한다. 이 경우에 관심 있는 물체의 확률분포는 자동으로 로케이션된 윈도우 내부의 화소들로부터 추정하고, 배경의 확률 분포는 물체의 윈도우를 둘러싸고 면적은 동일한 영역으로부터 추정한다. 다양한 IR 영상에 대한 분할 실험을 통해 제안한 분할 방법이 IR 영상의 분할에 적합함을 보이고, 기존의 IR 영상 분할 방법과의 비교 및 분석을 통해 제안 알고리듬이 우수한 분할 성능을 보임을 증명한다.