• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.218-223
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• 1999

국제 수로 기구(IHO, International Hydrographic Organization)에서는 해도제작을 위한 해양조사의 기준을 마련하고, 전세계적으로 사용되는 해도의 정확도를 표준화하고 있다. IHO에서는 탐사 기술의 발달을 반영하여, 기존의 단 빔 음향 측심기 이외에도 멀티 빔 음향 측심기(Multibeam Echo Sounder)와 사이드 스캔 소나(Side Scan Sonar)를 이용한 해양 탐사 시에 요구되는 정확도와 탐사 자료에 대한 메타 데이터(Metadata)의 작성을 요구하고 있다. 본 논문은 수로 측량에서 얻어진 측량 자료들의 처리절차와 자료관리 기법에 대한 연구이다. IHO 해양탐사 기준에 맞는 탐사 자료 처리와, 메타 데이터를 자동으로 생성하여 측량자료관리 DB구축 및 관리를 주 기능으로 하는 시스템을 설계하고 구현한다. 특히, 본 논문은 해양 탐사 자료 처리 시스템을 개발하기 위하여, 해양 자료 처리 과정을 표준화하고, 국제적 해양 자료의 교환 표준인 MGD77과 호환 가능한 메타 데이터를 자동 생성하며, 1Hz로 수집되는 GPS 측위자료로부터 특징점(Waypoint)을 정의하고, 이를 추출하여 측심선을 벡터화 (Trackline Vectorizing) 하는 알고리즘을 구현한다. 개발된 시스템은 현재 국립 해양조사원의 해양2000호에서 획득된 탐사자료에 적용, 운영되고 있다.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.5
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• pp.55-65
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• 2016

Detecting an object which is located at seabed is an important issue for various areas. This paper presents an approach to detection of an object that is placed at seabed in the shallow water. A conventional scheme is to employ a side-scan sonar to obtain images of a detection area and to use image processing schemes to recognize an object. Since this approach relies on high frequency signals to get clear images, its detection range becomes shorter and the processing time is getting longer. In this paper, we consider an active sonar system that is repeatedly sending a linear frequency modulated signal of 6~20 kHz in the shallow water of 100m depth. The proposed approach is to model consecutively received reflected signals and to measure their modeling error magnitudes which decide the existence of an object placed on seabed depending on relative magnitude with respect to threshold value. The feature of this approach is to only require an assumption that the seabed consists of an homogeneous sediment, and not to require a prior information on the specific properties of the sediment. We verify the proposed approach in terms of detection probability through computer simulation.

• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.3
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• pp.181-187
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• 2009

To estimate the status and volume of artificial reefs(ARs) deployed at the sea bottom in fishing grounds, this study assessed the initial volume of ARs, the cubic volume of AR groups, and the porosity of each AR using image data collected during a survey using a multi-beam echo sounder(MBES) and a side scan sonar(SSS). These results were compared with data collected during diver surveys and used to develop a new method and prediction formulas for countermeasures, facility volume, and efficient use of volume for deployed ARs(cubic concrete). The field survey results for nine ARs deployed in the Busan Sea region were calculated, and the average value of coefficient k(indicating the efficient use of volume ratio) among ARs was 0.753, and the correlation between coefficient k and year(Yr) of deployment was calculated as k=0.0023Yr+0.725. The relationship between these two factors was poor. In years following the deployment of artificial reefs, coefficient k and year of deployment were not correlated, in spite of the hardening ground due to subsidence and the reduced distance between ARs. Consequently, it is reasonable to suppose that coefficient k was defined by bottom surface conditions and initial deployment conditions.

• The Journal of the Acoustical Society of Korea
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• v.42 no.4
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• pp.370-376
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• 2023

In the underwater image, it is not clear to distinguish the shape of the target due to underwater noise and low resolution. In addition, as an input of deep learning, underwater images require pre-processing and segmentation must be preceded. Even after pre-processing, the target is not clear, and the performance of detection and identification by deep learning may not be high. Therefore, it is necessary to distinguish and clarify the target. In this study, the importance of target shadows is confirmed in underwater images, object detection and target area acquisition by shadows, and data containing only the shape of targets and shadows without underwater background are generated. We present the process of converting the shadow image into a 3-mode image in which the target is white, the shadow is black, and the background is gray. Through this, it is possible to provide an image that is clearly pre-processed and easily discriminated as an input of deep learning. In addition, if the image processing code using Open Source Computer Vision (OpenCV)Library was used for processing, the processing speed was also suitable for real-time processing.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.3
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• pp.275-281
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• 2011

To acquire an underwater topographic information is necessary for the design and construction of structures in marine and inland water. It consists of water depth information by bathymetric survey and underwater bottom topography image information can be obtained by side scan sonar in different ways. For the purpose of providing high quality data by means of engineering site survey, it is necessary to apply simultaneous acquisition of two information and carry out the integrated interpretation to each other. The present research aims to obtain information of the underwater topography and water depth at the same time using interferometer technique, and to validate interferometer technique with accuracy estimation.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.2
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• pp.193-200
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• 2013

In this paper, underwater acoustic image classification of a cylindrical object using the Hough transformation is proposed. Hough transformation is often used to classify a cylindrical object in the optical systems. However, it is difficult to apply to the underwater acoustic image system because of lower resolution and noisier underwater environments. Thus, the cylindrical object was modeled and its geometric depth(GD) pixels were restored in order to make them suitable for the Hough transformation by using moving average filter and a polynomial interpolation method. As a result, restored GD pixels are similar to original ones and test results show high performance in classification.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.5
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• pp.539-544
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• 2016

The aim of this study is identifying characteristics of spatial distribution using submerged debris data on the bottom of sea ground. Marine debris is classified into floating and submerged debris. These are polluting marine environment, ecology and habitat by floating and submerged. Also it takes a lot of money when it is to process the waste flowing into the ocean. In this study, it is used data of submerged debris by side scan sonar on the bottom of sea ground in Pohang port. Submerged distribution map is made to identify spatial classified characteristics of SMD(submerged marine debris) using by position and weight per area of SMD.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.1
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• pp.200-205
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• 2008

Stability and durability of the artificial reefs (ARs) installed for wildstock enhancement have been a key issue. We surveyed the stability of 4,044 artificial reefs installed at 5 sites (Gangeung, Donghae, Samcheok, Goseong. and Yangyang) along the Gangwon coast of the East Sea (Sea of Japan) through which 1 to 5 typhoons pass annually. The ARs surveyed were 7 types aging 1 to 4 years. The side scan sonar (SSS) and scuba diving surveys confirmed that the ARs stability was age and type-dependent. A total of 85.56% ARs remained safe. the rest 14.44% being influenced by physical parameters of the waters such as wave extremes mostly caused by typhoons. An interesting observation was that the AR were particulatly vulnerable to the wave extremes in the first year of installation, thereafter being less damageable. Representative damages of the ARs were capsized (0.20%). broken (5.79%), sunk (0.27%), and buried (8.18%). By type, dice reef was most stable. while semicircle branch reef was most vulnerable.

• Journal of Ocean Engineering and Technology
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• v.36 no.1
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• pp.61-81
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• 2022

The available underwater acoustic spectrum is limited. Therefore, it is imperative to avoid frequency interference from overlapping frequencies of underwater acoustic equipment (UAE) for the co-existence of the UAE. Cognitive technology that senses idle spectrum and actively avoids frequency interference is an efficient method to facilitate the collision-free operation of multiple UAE with overlapping frequencies. Cognitive technology is adopted to identify the frequency usage of UAE to apply cognitive technology. To this end, we investigated two principle underwater acoustic sources: UAE and marine animals. The UAE is classified into five types: underwater acoustic modem, acoustic positioning system, multi-beam echo-sounder, side-scan sonar, and sub-bottom profiler. We analyzed the parameters of the frequency band, directivity, range, and depth, which play a critical role in the design of underwater acoustic cognitive technology. Moreover, the frequency band of several marine species was also examined. The mid-frequency band from 10 - 40 kHz was found to be the busiest. Lastly, this study provides useful insights into the design of underwater acoustic cognitive technologies, where it is essential to avoid interference among the UAE in this mid-frequency band.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.1
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• pp.46-53
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• 2005

This paper describes the mean grain size and shear strength properties related to subsidence characteristics using sediment samples and acoustic images obtained from artificial reef areas in Tongyoung and Jangsungpo offshore. The acoustic images collected from chirp sonar and side scan sonar show well the attitude/orientation, the distribution pattern, and the degree of subsidence of artificial reefs, suggesting the possibility of suitable site investigation and the management of the reefs using acoustic sonar. The sediments were largely composed of clayey silt and silty clay. The mean grain sizes in Tongyoung and Jangsungpo offshore show the ranges of 5${\sim}$9${\Phi}$ and 8${\sim}$9${\Phi}$, respectively. The shear strength was significantly increased at the depths of 20cm in Tongyoung offshore and 80cm in Jangsungpo offshore, corresponding to the subsidence depth of artificial reefs. The relationship between mean grain size and shear strength did not show a correlation, suggesting the shear strength does not totally depend on mean grain size. Provided subsidence characteristics with respect to various artificial reefs and seabed condition are investigated in more details, the constructing area of the reef can be more extended.