• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4507-4513
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• 2013

The developing unmanned underwater equipment can be used for underwater construction site such as underwater leveling works. If a optical camera is applied to the unmanned underwater equipment, recognition in underwater can be gone to low due to high turbidity in working field. To overcome this problem, a sonar will be installed to the unmanned underwater equipment. In this study, the resolution of the sonar and the quality test of the sonar image under high turbidity environment were conducted. And the method to indicate the boundary of the underwater construction site was proposed. By these results, the basic performance of the sonar was evaluated.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.5
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• pp.482-491
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• 2021

It is obvious that understanding the effects of shallow water environment of Korea is very important to guarantee the optimal performance of active sonar such as monostatic and bistatic sonar. For this reason, in this paper, we analyzed the detection performance characteristics for various depth deployments of sonar in summer, winter and water temperature inversion environments, which environments are frequently observed in shallow water of Korea such as the Yellow sea. To analyze only effects of water temperature structures on target detection performance, we applied range independent conditions for bottom, sea surface and water temperature characteristics. To understand the characteristics of detection performance, we conducted transmission loss and signal excess modeling. From the results, we were able to confirm the characteristics of detection performance of active sonar. In addition, we verified that operation depth of transmitter and receiver affects the detection performance. Especially in the water temperature inversion environment, it was confirmed that the shadow zone could be minimized and the detection range could be increased through bistatic operation.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.6
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• pp.1095-1104
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• 2022

The towing cable plays a role in dropping and salvaging the Towed Array Sonar System (TASS) into the water and transmitting the signal (information) detected by the sonar in the water to the probe or surface ship. The towing cable consists of a heavy cable and a lightweight cable in detail. The towing cable for sonar is characterized by high reliability and durability as the underwater environment deteriorates as the operating depth increases. Due to these restrictions, cases designed and manufactured in Korea are extremely rare. The core technology for towing cable design secured through this study is expected to be used in various ways in the defense industry and the private sector.

• Journal of Sensor Science and Technology
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• v.32 no.2
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• pp.110-117
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• 2023

Reconstructing underwater geometry in real time with forward-looking sonar is critical for applications such as localization, mapping, and path planning. Geometrical data must be repeatedly calculated and overwritten in real time because the reliability of the acoustic data is affected by various factors. Moreover, scattering of signal data during the coordinate conversion process may lead to geometrical errors, which lowers the accuracy of the information obtained by the sensor system. In this study, we propose a three-step data processing method with low computational cost for real-time operation. First, the number of data points to be interpolated is determined with respect to the distance between each point and the size of the data grid in a Cartesian coordinate system. Then, the data are processed with a nonlinear interpolation so that they exhibit linear properties in the coordinate system. Finally, the data are transformed based on variations in the position and orientation of the sonar over time. The results of an evaluation of our proposed approach in a simulation show that the nonlinear interpolation operation constructed a continuous underwater geometry dataset with low geometrical error.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.94-100
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• 2017

In the case of the side scan sonar operated by the towing method, the underwater structure electric jig was developed because there is a difficulty in the cross-sectional survey that the user wants when conducting the survey. However, in the case of the sound wave photographing method using the electric jig, since the boat and the sonar behaves as one body, data distortion has occurred due to various problems according to working environment, such as, the rolling phenomenon of the boat due to the wave and the fluctuation of the sonic image due to the inoperability of the boat driver. Therefore, in order to solve the image blurring caused by the operation of the equipment for underwater survey of the existing side scan sonar, in this research, the program was supplemented to enable the shake correction by attaching the shake correction sensor and developing the shake correction algorithm. In order to verify the improvement of the sonar data resolution, the sonic images before and after the shake correction were collected through on-site investigation and the analysis of the sonic image data acquired by a diver measuring the actual damage length and depth. This study is expected to contribute to the development of sonar imaging technique of the underwater surface of the structure and bed surface of the sea or a river using the side scan sonar in the future.

• Geophysics and Geophysical Exploration
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• v.12 no.2
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• pp.192-198
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• 2009

Side scan sonar and SBP (sub-bottom profiler) play a very important role in the survey for seafloor imaging and sub-bottom profiling. In this study, we have acquired side scan sonar and SBP data from the artificial reef area. We applied digital image processing techniques to side scan sonar data in order to improve an image quality. For the enhancement of data quality and image resolution, we applied the typical seismic data processing sequence including gain recovery, muting, spectrum analysis, predictive deconvolution, migration to SBP data. We could easily estimate if artificial reef structures were settled properly and their distribution on the seafloor from the integrated interpretation of side scan sonar and SBP data. From the sampling analysis of seabed sediments, texture filtering of side scan sonar data and SBP data interpretation, we could evaluate the sediment type, distribution and thickness of seafloor sediments in detail.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.4
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• pp.245-251
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• 2019

Sonar bearing accuracy is the correspondence between the target orientation predicted by sonar and actual target orientation, and is obtained from measurements. However, when measuring sonar bearing accuracy, many errors are included in the results because they are made at sea, where complex and diverse environmental factors are applied. In particular, parallax error caused by the difference between the position of the GPS receiver and the sonar sensor, and the time delay error generated between the speed of underwater sound waves and the speed of electromagnetic waves in the air have a great influence on the accuracy. Correcting these parallax errors and time delay errors without an automated tool is a laborious task. Therefore, in this study, we propose a sonar bearing accuracy measurement equipment with parallax error and time delay error correction. The tests were carried out through simulation data and real data. As a result of the test it was confirmed that the parallax error and time delay error were systematically corrected so that 51.7% for simulation data and more than 18.5% for real data. The proposed method is expected to improve the efficiency and accuracy of sonar system detection performance verification in the future.

• Proceedings of the Korean Magnestics Society Conference
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• 1999.04a
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• pp.56-57
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• 1999

• 한국지구과학회:학술대회논문집
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• 2001.09a
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• pp.55-55
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• 2001

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.1-2
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• 2008