• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제16권8호
• /
• pp.2552-2570
• /
• 2022

Underwater images usually have various problems, such as the color cast of underwater images due to the attenuation of different lights in water, the darkness of image caused by the lack of light underwater, and the haze effect of underwater images because of the scattering of light. To address the above problems, the channel attention mechanism, strengthen-operate-subtract (SOS) boosting mechanism and gated fusion module are introduced in our paper, based on which, an underwater image recovery network is proposed. First, for the color cast problem of underwater images, the channel attention mechanism is incorporated in our model, which can well alleviate the color cast of underwater images. Second, as for the darkness of underwater images, the similarity between the target underwater image after dehazing and color correcting, and the image output by our model is used as the loss function, so as to increase the brightness of the underwater image. Finally, we employ the SOS boosting module to eliminate the haze effect of underwater images. Moreover, experiments were carried out to evaluate the performance of our model. The qualitative analysis results show that our method can be applied to effectively recover the underwater images, which outperformed most methods for comparison according to various criteria in the quantitative analysis.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제16권2호
• /
• pp.544-564
• /
• 2022

Underwater images often suffer from color distortion, blurring and low contrast, which is caused by the propagation of light in the underwater environment being affected by the two processes: absorption and scattering. To cope with the poor quality of underwater images, this paper proposes a multiscale fusion underwater image enhancement method based on channel attention mechanism and local binary pattern (LBP). The network consists of three modules: feature aggregation, image reconstruction and LBP enhancement. The feature aggregation module aggregates feature information at different scales of the image, and the image reconstruction module restores the output features to high-quality underwater images. The network also introduces channel attention mechanism to make the network pay more attention to the channels containing important information. The detail information is protected by real-time superposition with feature information. Experimental results demonstrate that the method in this paper produces results with correct colors and complete details, and outperforms existing methods in quantitative metrics.

• 전자공학회논문지
• /
• 제52권10호
• /
• pp.148-158
• /
• 2015

수중음향 채널환경에서 운영되는 검파시스템 성능분석은 실험의 제약으로 인해 모의 도구를 활용하여 시스템 성능을 결정한다. 본 논문은 수중음향 채널에 대한 탐지 효과도 분석을 위하여 수중환경 데이터베이스를 기반 수중음향 탐지 효과도 분석 모의 도구를 제안한다. 먼저, HYCOM 수중환경 데이터베이스 기반으로 수중 환경을 구축하고, 음선이론을 이용하여 수중음향 전달 경로/음압 계산을 통한 다중경로 지연 특성을 고려하였다. 또한, 실 환경에서 발생하는 수중 잡음 특성을 반영하기 위해 운용 주파수에 따른 수중청음기/수중음향 채널 잡음 특성인 열잡음/수중 주변 잡음을 적용하였다.

• 한국해양공학회지
• /
• 제30권3호
• /
• pp.227-233
• /
• 2016

This paper presents an underwater structure 3D reconstruction method using a 2D multibeam imaging sonar. Compared with other underwater environmental recognition sensors, the 2D multibeam imaging sonar offers high resolution images in water with a high turbidity level by showing the reflection intensity data in real-time. With such advantages, almost all underwater applications, including ROVs, have applied this 2D multibeam imaging sonar. However, the elevation data are missing in sonar images, which causes difficulties with correctly understanding the underwater topography. To solve this problem, this paper concentrates on the physical relationship between the sonar image and the scene topography to find the elevation information. First, the modeling of the sonar reflection intensity data is studied using the distances and angles of the sonar beams and underwater objects. Second, the elevation data are determined based on parameters like the reflection intensity and shadow length. Then, the elevation information is applied to the 3D underwater reconstruction. This paper evaluates the presented real-time 3D reconstruction method using real underwater environments. Experimental results are shown to appraise the performance of the method. Additionally, with the utilization of ROVs, the contour and texture image mapping results from the obtained 3D reconstruction results are presented as applications.

• 한국정보통신학회논문지
• /
• 제25권2호
• /
• pp.327-329
• /
• 2021

Underwater acoustic communication channel is influenced by environmental parameters such as multipath, background noise and scattering. Therefore, a transmitted signal is influenced by the sea surface and the sea bottom boundaries, and a received signal shows a delay spread. These factors create a noise in the image and degrade the quality of underwater acoustic communication. To solve these problems, in this paper, we evaluate the performance of an underwater acoustic communication model using a denoising auto-encoder used for unsupervised learning. Noise images generated by the underwater multipath channel were collected and used as training data. Experimental results were analyzed as a PSNR parameter that expressed the noise ratio of the two images.

• Journal of information and communication convergence engineering
• /
• 제8권2호
• /
• pp.163-167
• /
• 2010

In underwater acoustic communication, acoustic signals from transducers or hydrophones are used. And the underwater acoustic communication channels are very complicated, because of vertical distribution of acoustic velocity according depths, and reflections from boundaries like as surface or bottom. For the implementation of the underwater acoustic communication channel, the image method or ray tracing method have been used. In this paper, we introduce a new approach for implementation of underwater acoustic communication channel using the simulation of the Transmission Line Matrix Modeling and cross-correlations from the input and output signals.

• 한국멀티미디어학회논문지
• /
• 제18권4호
• /
• pp.506-523
• /
• 2015

The intent is to determine whether or not the custody transfer is helpful for data transmission in challenging underwater communications when running Bundle protocol or underwater protocols. From the point of view defending side, Underwater Acoustic Network (UAN) will be a serious threat for its strong functionality long rang and high precision of surveillance and detection. Therefore, countermeasures must be taken to weaken its effect. Our purpose is analyzed that how to benefit from the UIoT to learn from, exploit and preserve the natural underwater resources. Delay/Disruption Tolerant Network (DTN) is essential part of the network heterogeneity communication network. The vulnerability and potential security factors of UIoT are studied thereafter. Security mechanisms for an underwater environment are difficult to apply owing to the limited bandwidth. Therefore, for underwater security, appropriate security mechanisms and security requirements must be defined simultaneously. The paper consists of mathematical and security model. Most important point of view in the security challenges of effective Buffer and Storage management in DTN.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제9권3호
• /
• pp.256-265
• /
• 2017

In this paper, an ascheme is proposed for multiuser underwater acoustic communication by using the multi-chirp rate signals. It differs from the well known TDMA (Time Division Multiple Access), FDMA (Frequency Division Multiple Access) or CDMA (Code Division Multiple Access), by assigning each users with different chirp-rate carriers instead of the time, frequency or PN code. Multi-chirp rate signals can be separated from each other by FrFT (Fractional Fourier Transform), which can be regarded as the chirp-based decomposing, and superior to the match filter in the underwater acoustic channel. VTRM (Virtual Time Reverse Mirror) is applied into the system to alleviate the ISI caused by the multipatch and make the equalization more simple. Results of computer simulations and pool experiments prove that the proposed multiuser underwater acoustic communication based on the multi-chirp rate exhibit well performance. Outfield experments carrie out in Xiamen Port show that using about 10 kHz bandwidth, four users could communicate at the same time with 425 bps with low BER and can match the UAC application.

• 대한전자공학회논문지TC
• /
• 제48권1호
• /
• pp.38-44
• /
• 2011

수중 환경의 복잡성 때문에 수중통신은 대기중에서의 통신과는 그 차이가 상당한 여러 가지 어려움들을 가지고 있다. 신호는 수중에서 많은 불규칙 소음들에 의해 저하된다. 뿐만 아니라 대역폭의 한계는 수중 통신에서 매우 큰 이슈이다. 그러므로 배열신호 처리 기법은 SNR을 개선에 적당하다. 이 논문에서 소스 추적기법에 기반한 수중 통신을 목적으로 하는 potential 기법을 제안하고자 한다. 또한 다중배열 소나를 이용한 새 추적 모델과 동 소나의 세부 구성을 제시했다. 실험들에서는 샘플 모델과 본 모델상에서 추적 결과의 차이점을 도출해 냈다. 실험 결과, 특히 수중환경에서 통신 문제들을 해결할 가능성이 수신기 구성이라는 것을 시연하였다.

• 전자공학회논문지
• /
• 제53권3호
• /
• pp.91-98
• /
• 2016

소나 영상에서 수중 물체의 검출과 분류는 도전적인 과제이다. 본 논문에서는 소나 영상과 영상처리기법을 이용하여 해저의 물체를 식별하는 시스템을 제안한다. 수중 물체의 식별 과정은 수중 물체 후보 영역 검출과 물체 식별의 두 단계로 구성된다. 영상 정합(image registration) 기법을 이용하여 수중 물체 후보 영역을 검출하고, 기존에 획득된 기준 배경 영상과 현재 스캔된 영상 사이의 공통된 특징점을 검출하여 정합한 후, 두 영상의 차 영상(difference image)을 구하여 검출한다. 검출된 물체는 고유벡터와 고유값을 특징으로 사용하여 데이터베이스내의 패턴과 가장 유사한 패턴으로 분류한다. 제안하는 수중 물체 식별 시스템은 최단 소행 항로(Q route) 확보와 같은 응용에 효율적으로 사용될 수 있을 것으로 기대된다.