• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.30 no.4
• /
• pp.251-262
• /
• 1994

The speed of vertical migration and the volume backscattering strength of the scattering layers during the evening and morning transitions between day and night were measured in November 1990-1992 in thermally stratified waters of the East China Sea. Acoustical measurements were carried out using a scientific echo-sounder operating at t재 frequencies of 25 and 100kHz, and using an echo-integration system connected with a micro-computer. Biological sampling was accomplished by bottom trawling to identify fish species recorded on the echo sounder, and the species and length compositions were determined. The values of scattering strength were allocated to group of fishes according to the fish traces on the echo recording paper and the species composition of trawl catches. The vertical velocities of migration derived from the changes in the depths and the values of peak scattering strength of the dense layer vertically migrating toward the bottom or toward the surface. The trawl data suggest that snailfish and fishing frog were the most abundant fishes in all research stations. As sunrise approached, the fish formed a strong concentration just above the thermocline. The the highest values of scattering strength in the entire water column appeared in the depth strata above the thermocline just before the begining of downward migration. As soon as the fish began to migrate downwards across the thermocline, the values of the scattering strength in the depth strata above the thermocline rapidly decreased, while the values for the scattering layer moving slowly toward the bottom gradually increased. During the 1992 surveys, the speed of the vertical migration was estimated to be 0.38m/min in the upward migration and 0.32m/min in the downward migration, respectively. That is the rate of vertical migration was slightly higher at dusk than at dawn. Similar migration patterns were observed on different stations and under different weather conditions during the surveys in 1990.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2011.06a
• /
• pp.236-236
• /
• 2011

• Proceedings of the Korean Society of Fisheries Technology Conference
• /
• 2005.11a
• /
• pp.3-6
• /
• 2005

• The Journal of the Korea institute of electronic communication sciences
• /
• v.15 no.2
• /
• pp.327-334
• /
• 2020

In this paper, an automatic cruise system of unmanned boat was developed for surveying water depth in reservoir using accurate location information. Using global satellite navigation system(GNSS) data in real time, this unmanned system, combined with an echo sounder, can simultaneously collect location information and depth information on the reservoir. This automatic navigation system allows the automatic route generation program to automatically generate a cruise route according to the input conditions for grid sizes of 5m, 10m and 20m, and automatically controls the cruise route with high positional accuracy. The developed system was tested to verify the applicability of the selected Yonggok(Geoncheon) reservoir as a test reservoir located in Suncheon, Jeollanam-do.

• Journal of the Korean Society of Industry Convergence
• /
• v.24 no.1
• /
• pp.61-67
• /
• 2021

With the recent development of bathemetry technology, the hydrographic surveying method has been changed from single beam depth device use to multi beam acoustic sounding technology. Also, various studies have been reported to obtain high accuracy and precision in the process of river bed topographic data. Especially south korea is geographically on three sides of the sea and the river topography is very developed. To build information about the underwater, and riverbed status, the public investigations has been continuously progressed. In this study, We investigasted the riverbed topography near Baeckma river leisure park. for this purpose, In this study, as the first preliminary survey, location of navigational dangerous objects and reefs and the dangerous areas are identified. Also, ground control points is selected for the optimal GPS surveying. Secondary, through test surveying the Gain, TVG, and pulse length are determined. In addition, the investigation of dangerous objects for navigation is also conducted. As the last step, the error analysis are conducted for the acquired data, and this process involves the removal and adjustments of errors. This section includes the analysis of tide level and navigational contributions, and finally generates a submarine topographic map.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.26 no.1
• /
• pp.14-19
• /
• 1990

This paper describes on the characteristics of the acoustic echoes from the scattering layers by the aggregation of marine organisms which was measured by using a 50kHz echo sounder on board of the training ship SAEBADA belong to National Fisheries University of Pusan during the summer, 1989 in the East China Sea. A data acquisition system was used to record digitally the envelope of the echoes and the frequency distribution of echo amplitudes on the whole water column was examined as a function of time during the sunrise and sunset periods. Acoustic data showed that the abundance distribution of marine organisms according to depth in the servery area changed with time and that the organisms were most active during the twilight of morning, and the echo strength on the water column or scattering layer was also strongest during this time. Additional results of this survey suggest that other interest, such as the relationship between environmental conditions and biomass depth distribution, could be also investigated in hydroacoustic method.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.35 no.2
• /
• pp.170-177
• /
• 1999

In order to research the relationship between distribution of fish and the ocean environment in Southern Sea of Korea, echo survey and oceanographic observation were carried out from July 27 to 31 in 1998. The DSL(Depth Scattering Layer) and high density of fishes were appeared in northeastern Cheju Island and offshore of Karnak bay by color echo sounder. The relative Sa(area backscattering coefficient) in offshore of Karnak bay was 5,500 at 28KHz, 12,500 at 200KHz and Northeastern Cheju Island was 6,000 at 28KHz, 20,000 at 200KHz. During the acoustic survey period, Ocean environment of high density of fishes area were as the follows. The surface Northeastern Cheju Island were ranged 20~$26.5^{\circ}C,\;31.5~32.5\perthousand$ and that bottom were ranged 16~$20^{\circ}C,\;35.4~34\perthousand$. The shallow water area in offshore of Karnak bay were ranged 24~$26.5^{\circ}C,\;30.0~31.5\perthousand$

• Journal of Korean Society for Geospatial Information Science
• /
• v.10 no.1 s.19
• /
• pp.27-35
• /
• 2002

The dam made reservoir, a major means to overcome the problems caused by water resource's uneven supply by time and space, plays an important role, particularly, of water supply. The role of water supply will get more important, considering the usage of water resource becomes more intensive. Therefore, it is continuously required to construct new dams securing water supply and to study on effective operation plans of the dam. The size of reservoir needs to be measured according to possible supply estimation in the pre-design stage. The depth of water, at this point, should be taken. Among many ways of sounding, echo sounding has been frequently used recently. This study, therefore, presents a new way of sounding that takes less time with stronger accuracy, uniting GPS and echo sounder to apply a means of obtaining three dimensional position data. This enables the designer to escape from the conventional way of sounding in the estimation of reservoir to design and redesign a new dam.

• Smart Media Journal
• /
• v.5 no.1
• /
• pp.9-14
• /
• 2016

Although the ocean observation and exploration equipment is necessary for the oceanographical observation and strengthening influence of the nation and the resource preemption, it depended on the oversees adoption rather than the domestic development. The MBESs were developed for seabed topography, sedimentary distribution information and underwater objects exploration, but there is no domestic production. So in this research we try the localization of the marine acoustic sounder. Especially about correcting the error occurred on the hardware, we confirmed it on software.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.26 no.1
• /
• pp.51-56
• /
• 1990

The authors carried out an experiment to investigate the echo fluctuations from ocean bottom due to ship's motion. The bottom echoes was continuously measured, by using a 50 kHz Echo sounder on board of the ship being at anchor under the sea condition of 15 knots in wind velocity and approximately 2 meters in wave height, to extract the information about the pulse stretching and the ship's motion from the first return and the second return. A data acquisition system was used to record digitally the envelope of the echoes, and the analysis was applied to the echo data collected from the continental shelf in the South China Sea. The results obtained can be summarized as follows: 1. The equivalent pulse width of the second return echoes from ocean bottom was 2.4 times longer than that of the first return echoes. 2. The echo peak values of the first return fluctuated markedly than that of the second return and was shown to be extremely sensitive to small change in ship's motion. 3. Energy target strength and peak target strength of the sandy-mud bottom were -13.4 dB and -14.6 dB, respectively.