• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.5 no.2
• /
• pp.385-391
• /
• 2001

In this study, we will develop the sea surface interpretation system that can aware the target in the bottom of the sea. we will setup the database whose records would be the signal patterns of formation about mud, sand, rock and sea shell achieved by using supersonic. then we will convert analog signal received in fish detector to digital one using A/D converter So we can process and analyze this signal pattern then compare it to the one in our Database at the real time to identify the target in the bottom of the sea. After enough times of experiments from the background of the results that have been achieved from many studies(including a water tank experiment and a field investigation), we can aware the exact information of the sediment and the sand in the sea. By analyzing the first, second and third signal of the supersonic characters reflected from the body of a fish categorized by its family and from the body of shellfish, muddy sand, sand and rocks, We will develop the sea surface decipherment system which abstracts the first signal that shows the target in the bottom of the sea and makes the second and third signals filtering.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.05a
• /
• pp.383-387
• /
• 2001

The sea flower begins at the water-sediment Interface. In the ocean basins, the sound velocity of the sediments at the interface vary from a few percent less than the sound speed in water just above the interface to somewhat greater. Marine sediments are unconsolidated; that is, the particles are not cemented of fused together. Samples feel like mud, muddy sand, sand, and so on. With the theoretical knowledge, the systematic research on the searching capability of Ultra Sonic Signal will be continued to identify the influence against the sea water subject. In this research, signal will be analyzed according to the influence range, power and sensitiveness of Ultra Sonic Generator. In addition, the radius of Ultra Sonic Signal will be included. The experimental field work will be executed at Nockdong, Pulkyo and other places well known as a habitat of Pan Shell.

• The Journal of the Acoustical Society of Korea
• /
• v.34 no.6
• /
• pp.432-443
• /
• 2015

Coherence describing the similarity between physical quantities of two signals is a very useful tool to investigate the temporal and spatial characteristics of signals propagating in underwater acoustic waveguide. Ambient noise measurements were made by the vertical received array consisting of three hydrophones as part of the KIOST-HYU joint acoustics experiment, and the coherence for the underwater ambient noise was analyzed. In this paper, the coherence results in cases that the generator in the research vessel was off and turned on are presented. The coherence estimated in the case of the generator operation mode are compared to the predictions obtained using the theoretical model with the directional density function dominated by vertical components propagating downward from the ship. In the case of the generator switch-off, the results are compared to the model predictions with directional density function including the effects of sea surface noise and long-distance shipping noise.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.27 no.4
• /
• pp.266-277
• /
• 1991

To catch the surf clam, Mactra chinensis, in sand bottom using the excavating performance of water jet, the authors had constructed the experimental hydraulic jet dredge by the result of water tank experiment of previous report, and also were carried out the field experiments in the surf clam fishing ground near Kunsan, Korea from 5th to 30th of October, 1990. The results obtained are as follows. 1) Excavating depth was more than 10~11cm at the 1500cm/s water-jet velocity in the fine sand and muddy sand. 2) Towing tention was only 105$\pm$5kg in the 6.7cm/s towing speed. 3) Average catch amount per unit towing area was 0.42kg/m super(2) and it was 1.2~1.6 times comparing on the conventional dredge. 4) Experimental hydraulic jet dredge did not nearly brake the surf clam. 5) Turbidity variation by the water jet of dredge was not serious in the fishing ground; On the surface, when the depth is more than 5.2m, turbidity variation was not found at all, and on the 3m layer above the bottom, turbidity variations was increased 9~11ppm at 1m backward from the dredge, but it was gradually decrease, and it was nearly not at 9m backward from the dredge.