• Journal of the Mineralogical Society of Korea
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• v.28 no.2
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• pp.135-145
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• 2015

In order to predict the deterioration of stone monument due to acid fog, an artificial fog test using pH4.0 and pH5.6 was applied to the Gyeongju Namsan granite, decite and marble. After the test had weathered Gyeongju Namsan granite a larger weight reduction due to acid fog than fresh one. Decite has shown the most significant changes among the tested rocks with about 0.005 % of weight reduction. Decite and weathered granite will have considerable weight reduction due to acid rain than the acid fog, whereas the marble was expected to show a weight reduction regardless of the phase of water. The porosity and water absorption rate of weathered granite had significantly increased. This result means that the weathered rock is predicted to be more susceptible to acid fog than the fresh rock. The absorption rate of the marble after the test had shown approximately 50 % increase. The color of the samples had slightly changed towards yellow, such tendency was greater shown in weathered rocks. The marble reacted with acid fog had an increased whiteness. A large amount of cation in the samples is caused mainly by the dissociation of minerals through the reaction with acid fog.

• Journal of Korean Society of Disaster and Security
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• v.11 no.2
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• pp.69-74
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• 2018

Fog to which environmental impacts are sensitive has a danger to the safety of citizens due to the difficulty in predicting the specific area/time zone. Therefore, we propose a white smoke fog reduction technique using a fog removal device that can remove fog particles directly through dry air and anionic condensation nucleus instead of conventional passive countermeasures. In this study, to verify the effect of reducing fog and the effect of temperature on the white smoke fog which is frequently occurred in the detention basin. As a result, the visible distance of 100m or more was secured within 30 seconds, and it was confirmed that the fog reduction effect is more effective. Also, the lower the temperature, the larger the amount of white smoke fog was. However, the effect of reducing the white smoke fog by temperature was insignificant. Through this experiment, it was possible to verify the reduction effect of the white smoke fog generated in the detention basin through fog removal device.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.6
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• pp.819-824
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• 2021

As technologies related to image processing such as autonomous driving and CCTV develop, fog removal algorithms using a single image are being studied to improve the problem of image distortion. As a method of predicting fog density, there is a method of estimating the depth of an image by generating a depth map, and various fog features may be used as training data of the depth map. In addition, it is essential to implement a hardware capable of processing high-definition images in real time in order to apply the fog removal algorithm to actual technologies. In this paper, we implement NLCV (Normalize Local Coefficient of Variation), a feature of fog based on coefficient of variation, in hardware. The proposed hardware is an FPGA implementation of Xilinx's xczu7ev-2ffvc1156 as a target device. As a result of synthesis through the Vivado program, it has a maximum operating frequency of 479.616MHz and shows that real-time processing is possible in 4K UHD environment.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2001.05a
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• pp.206-208
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• 2001

• Journal of Broadcast Engineering
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• v.22 no.1
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• pp.118-127
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• 2017

We propose the dehazing algorithm which consists of two main parts, the derivation of the Atmospheric light and adaptive transmission map. In the getting the Atmospheric light value, we utilize the quad-tree partitioning where the depth of the partitioning is decided based on the difference between the averaged pixel values of the parent and children blocks. The proposed transmission map is adaptive for each pixel by using the parameter ${\beta}(x)$ to make the histogram of the pixel values in the map uniform. The simulation results showed that the proposed algorithm outperforms the conventional methods in the respect of the visual quality of the dehazed images and the computational complexity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.1-7
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• 2019

This paper presents low-complexity single-image dehazing to enhance the visibility of outdoor images that are susceptible to degradation due to weather and environmental conditions, and applies it to various devices. The conventional methods involve refinement of coarse transmission with high computational complexity and extensive memory requirements. But the proposed transmission estimation method includes excellent edge-preserving performance from comparison of the pixel-based dark channel and the patch-based dark channel in the vicinity of edges, and transmission can be estimated with low complexity since no refinement is required. Moreover, it is possible to accurately estimate transmissions and adaptively remove haze according to the characteristics of the images via prediction of the atmospheric light for each pixel using joint bright and dark channel (JBDC). Comprehensive experiments on various hazy images show that the proposed method exhibits reduced computational complexity and excellent dehazing performance, compared to the existing methods; thus, it can be applied to various fields including real-time devices.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.1
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• pp.257-264
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• 2019

This paper presents a single image haze removal method via a pixel-based joint BDCP (bright and dark channel prior) and a hierarchical bilateral filter in order to reduce computational complexity and memory requirement while improving the dehazing performance. Pixel-based joint BDCP reduces the computational complexity compared to the patch-based DCP, while making it possible to estimate the atmospheric light in pixel unit and the transmission more accurately. Moreover the bilateral filter, which can smooth an image effectively while preserving edges, refines the transmission to reduce the halo effects, and its hierarchical structure applied to edges only prevents the increase of complexity from the iterative application. Experimental results on various hazy images show that the proposed method exhibits excellent haze removal performance with low computational complexity compared to the conventional methods, and thus it can be applied in various fields.

• 한국항공운항학회:학술대회논문집
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• 2005.11a
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• pp.7-10
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• 2005

• 한국항공운항학회:학술대회논문집
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• 2004.11a
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• pp.62-65
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• 2004

• 한국항공운항학회:학술대회논문집
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• 2007.06a
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• pp.11-12
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• 2007