• Journal of the Korea Computer Graphics Society
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• v.25 no.5
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• pp.1-9
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• 2019

In this paper, we propose a video enhancement method using generative adversarial networks to remove raindrops and restore the background information on the removed region in the coastal wave video imagery distorted by raindrops during rainfall. Two experimental models are implemented: Pix2Pix network widely used for image-to-image translation and Attentive GAN, which is currently performing well for raindrop removal on a single images. The models are trained with a public dataset of paired natural images with and without raindrops and the trained models are evaluated their performance of raindrop removal and background information recovery of rainwater distortion of coastal wave video imagery. In order to improve the performance, we have acquired paired video dataset with and without raindrops at the real coast and conducted transfer learning to the pre-trained models with those new dataset. The performance of fine-tuned models is improved by comparing the results from pre-trained models. The performance is evaluated using the peak signal-to-noise ratio and structural similarity index and the fine-tuned Pix2Pix network by transfer learning shows the best performance to reconstruct distorted coastal wave video imagery by raindrops.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.10 no.1
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• pp.45-53
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• 1998

Video monitoring techniques and their applications to beaches were reviewed. The recent development of video hardware and image process made it possible to measure shoreline changes, sandbar morphology, wave runup, swash motion, and so on using video camaras. Especially, quantitative information from the video image can be obtained by digitization of image, rectification procedure, and image process. Using video monitoring techniques, measurements can be made at much lower cost and for long periods of time compared to the traditional measurement techniques, although these techniques are of lower accuracy and provide only indirect information on the land and water surface.

• Journal of the Korea Computer Graphics Society
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• v.25 no.4
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• pp.9-16
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• 2019

In this paper, we propose a hydrodynamic scene separation method for wave propagation from video imagery using autoencoder. In the coastal area, image analysis methods such as particle tracking and optical flow with video imagery are usually applied to measure ocean waves owing to some difficulties of direct wave observation using sensors. However, external factors such as ambient light and weather conditions considerably hamper accurate wave analysis in coastal video imagery. The proposed method extracts hydrodynamic scenes by separating only the wave motions through minimizing the effect of ambient light during wave propagation. We have visually confirmed that the separation of hydrodynamic scenes is reasonably well extracted from the ambient light and backgrounds in the two videos datasets acquired from real beach and wave flume experiments. In addition, the latent representation of the original video imagery obtained through the latent representation learning by the variational autoencoder was dominantly determined by ambient light and backgrounds, while the hydrodynamic scenes of wave propagation independently expressed well regardless of the external factors.

• Magazine of the Korean Society of Hazard Mitigation
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• v.7 no.1 s.24
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• pp.47-56
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• 2007

자원개발 및 해사채취 그리고 최근에는 기후변화에 따른 해수면상승, 고파랑 및 태풍강화 등의 영향으로 연안침식이 가속화되고 있어 연안재해의 측면에서 체계적이며 지속적으로 관리할 필요성이 제기되고 있다. 이에 본 연구에서는 끊임없이 변화하고 있는 해수 욕장의 해안선 변화를 파악하기 위하여 매우 경제적이고 연속적으로 해안선 변화를 파악할 수 있는 비디오 영상을 이용한 모니터링 기법을 이용하여 2003년 부터 우리나라 주요 20개 백사장에 대해 연안침식의 정량적 현황분석을 실시하여 왔다. 그 외에도 백사장 62개소에 대해 모니터링의 일환인 연안침식 이력조사를 매년 실시하여 침식현황에 대한 정성적 평가를 실시하고 있다. 모니터링에 의한 침식현황 분석결과에 의하면 우리나라의 전 연안은 양빈을 실시하여 인위적으로 현상황을 유지하고 있는 몇몇 지역을 제외하고는 완만한 침식경향을 보이고 있어 대책수립의 필요성이 제기되고 있다. 더욱이 전국적으로 침식지역이 확대되고 있어, 2007년${\sim}$2010년까지 주요 백사장 16개소에 비디오 모니터링 체계를 추가 구축하고 전국 120개의 침식 지역에 대하여 침식이력조사를 확대 수행하여 연안관리 및 대책수립에 필요한 기초자료를 축적할 계획이다.

• Ocean and Polar Research
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• v.31 no.4
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• pp.415-422
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• 2009

The wave observation system in Korea has been established with an emphasis on pointmeasurement based on in situ instrumentations. However, the system cannot fully investigate the coastal wave-related problems that are significantly localized and intensified with three-dimensional regional geometries. Observation technique that can cover local processes with large time and spatial variation needs to be established. Video imaging techniques that can provide continuous monitoring of coastal waves and related phenomena with high spatial and temporal resolutions at minimum cost of instrumentation risks are reviewed together with present status of implementation in Korea. Practical applications of the video imaging techniques are suggested to tackle with various coastal issues of public concern in Korea including, real-time monitoring of wave runup and overtopping of swells on the east coast of Korea, longshore and rip currents, morphological and bathymetric changes, storm surge and tsunami inundation, and abnormal extreme waves in the west coast of Korea, etc.