• Journal of Environmental Science International
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• v.13 no.6
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• pp.561-570
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• 2004

This study was carried out to survey the pollution of nonylphenol (NP) in surface sediments around Gwangyang bay and Yeosu sound. NP was suspected chemicals as endocrine disruption. Gwangyang bay is located on the mid south coast of Korea. It is a semi-closed bay which Yeosu petrochemical industrial complex, POSCO (Pohang Steel Company) and Gwangyang container harbor are there. The surface sediments were collected at 15 stations with gravity corer at October, 1999, February, May and August, 2000. Also, the stream and intertidal sediment were collected at 5 sites at August, 2000. Concentrations of NP in surface sediments were in the range of 6.89 to 202.70 ng/g dry wt.. Seasonal range (mean value) of NP is 13.98 to 30.48 (23.46) ng/g dry wt. at October, 10.35 to 54.91 (28.10) ng/g dry wt. at February, 29.05 to 202.70 (82.32) ng/g dry wt. at May and 6.98 to 83.40 (25.37) ng/g dry wt. at August. NP was seasonally fluctuated, and the highest mean value and range was detected at May, 2000. NP was highly distributed in the inner part of Gwangyang bay than Yeosu sound. Concentrations of NP in stream and intertidal sediments showed the highest value in downstream near Yeosu petrochemical industrial complex and Yondung stream. It suggests that the source of NP is industrial wastewater and municipal sewage.

• Economic and Environmental Geology
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• v.33 no.5
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• pp.425-434
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• 2000

The 3.5 KHz seismic survey was carried out for studying the distribution pattern of the unconsolidated sediments of the Yeosu Sound on the southern coast of the Korean Peninsula. Field data originally recorded in analog are converted and processed digitally to recover the high-resolution acoustic profiles. Across the north-south trending channel with the depth of 20~30 m, different seismic facies types are observed in the top section of sediments. The western part is characterized by the continuous high-amplitude subparallel reflectors within which the acoustic turbidity as a token of the presence of gas is commonly observed, whereas the counterpart largely shows poor reflectors and has shallow acoustic basement toward the north. The dissimilarity of the seismic expression across the channel can be interpreted as the result of the change of depositional environment caused by relative sea-level fluctuations of the late-Quaternary. During the last glacial period, the Yeosu Sound was exposed and eroded by the paleo-Seomjin River. By the following rapid rise of sea level, it was covered by the transgressive sand sheet. When the sea level reached near the present position, the muddy sediment has accumulated only in the western part of the Yeosu Sound as its depositional front has moved toward the north. It is partly caused by the asymmetrical tidal current in the Yeosu Sound where the flood near the bottom has stronger current flow and contains more suspended sediments.

• Fisheries and Aquatic Sciences
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• v.13 no.2
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• pp.157-166
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• 2010

We investigated the benthic polychaete assemblage in Gwangyang Bay and Yeosu Sound in February 1997. The sediment was an almost entirely muddy facies. The benthic macrofauna comprised 295 species occurring at a mean density of 875 $indiv./m^2$. Polychaetes were the major faunal component; there were 94 species at mean density 765 $indiv./m^2$. The highest abundance and species richness occurred in the Myodo south and north channels, in the mouth of Gwangyang Bay, and in the Noryang channel mouth. The most abundant polychaete was Tharyx sp. (47.9%), followed in rank order by Heteromastus filiformis (9.6%), Melinna cristata (9.3%), and Lumbrineris longifolia (7.3%). Cluster analysis divided the study area into four station groups based on station similarities in benthic polychaete assemblages: the Glycinde-Prionospio cluster in the western inner bay, the H. filiformis cluster in the middle inner bay, the Melinna-Lumbrineris cluster in the Myodo south-north channel, and the Tharyx cluster in the eastern main channel region. The sediment type of Gwangyang Bay has changed gradually from sandy to muddy. Dominant species have also changed from Chone teres and Lagis bocki to Tharyx sp., which is a potential organic pollution indicator.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.4
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• pp.434-444
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• 1994

Physical and acoustic properties of sediment core samples recovered from the Kwangyang Bay, the Yeosu Sound, and the inner shelf of central South Sea, Korea were investigated. Compressional wave velocity, density, porosity, and shear strength were measured at 10cm interval's along the core depth. Sediment texture(grain size, sand, silt, and clay contents) were also measured and correlated with the physical properties(density, porosity, and shear strength). The physical and acoustic properties of the sediment changed gradually from the Kwangyang Bay to the shelf area in accordance with the distance from the input source of the terrigenous sediment. The Yeosu Sound acted as a route of sediment transport from the estuary(the Seomjin River) to the shelf and vice versa. The physical and acoustic properties of the Yeosu Sound sediment conformed to an intermediate stage between river mouth and shelf areas. These results can be utilized to trace the influence of the Seomjin River on the so-called mud belt of Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.3
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• pp.266-270
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• 1985

In order to obtain the fishing possibility by acoustic, the two fishes, Lateolabrax japonicus, Mugil cephalus, were bred in a water tank. The feeding sounds from the fishes and the artificial sounds were recorded by a hydrophone and then the frequency and the sound pressure level of the sounds recorded were analyzed by the digital frequency analyzer. These sounds were edited in two manners of which one is emitted for 10 seconds and paused for 10 seconds continuously and the other is emitted for 20 seconds and paused for 20 seconds also. These edited sounds were emitted again into the tank and the respose of fisher were observed. Lateolebrax japonicus showed a positive response and Mugil cephalus responsed a little positively to the emitted feeding sound, The fishes seemed to show a positive response only in emitting a moderate pressure level of feeding sound. Lateolabrax japonicus and Mugil cephalus showed negative response to the emitted artificial sound. It was most effective to increase the sound pressure level that the fishes went away from the sound source to the emitted artificial sound.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.1
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• pp.31-38
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• 1991

Suspended sediment budget in Gwangyang Bay was investigated using the data of suspended sediment concentration and vertical distribution of tidal currents at the mouth of the bay in the Yeosu Sound (Yeosu Haeman) . At the mouth of the bay suspended sediment concentration shows much higher value of approximately 17.80mg/l on the average near the bottom than the concentration near the surface where the average is 4.7mg/l. Tidal currents also show an asymmetry in magnitude between flood and ebb. Near the surface ebb is stronger than flood, while flood is stronger than ebb near the bottom. Due to the higher concentration and stronger flood current near the bottom, transport of suspended sediment near the bottom plays a major role to the sediment budget in the bay, and the bay is in net-depositional environment. The western part of the bay seems to gain the suspended sediment of approximately $5.66\times10^8g/day$, which corresponds to a sedimentation rate of about 1.15m/1,000years.

• Economic and Environmental Geology
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• v.33 no.3
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• pp.239-246
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• 2000

The 3.5kHz sub-bottom profiling was carried out over both Gwangyang Bay and the Yeo Sound . High -resolution digital images of uppermost sediment layers are obtained from the field data which were originally recorded in analog mode. Most prominent feature along the acoustic profiles is the chaotic reflections which imply the presence of shallow gas within the silty sediments. In the western part of Gwangyang Bay, the gas-charged sediments are assoicated with the acoustic turbidity of the blanket type. Across the Seomjin Delta in the eastern part of Gwangyang Bay, the gas-charged seismic facies are observed just beneath the sea bottom. In the western Yeoul Sound , the gassy seiments occur widely , whereas it is rare in the eastern counterpart with the <30-m-deep channel. We postulate that this gas was biogenetically produced within the organic-rich deposits.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.18 no.2
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• pp.71-75
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• 1982

The feeding sounds of three fishes, Lateolabrax japonicus, stephanolepis cirrhifer and Fugu vermicularis were recorded in the tank, and the frequency and the sound pressure level were analyzed. The recorded sounds were emitted again into the tank and the response of fishes were observed. The results obtained are summarized as follows: 1) The frequency and the sound pressure level of the feeding sound of Lateolabrax japonicus, Stephanolepis cirrhifer, and Fugu vermicularis are 80~350 Hz and 250~500 Hz, and 101~103 dB, 106~115 dB and 102~112dB. 2) It was most effective to increase the sound pressure level as much as dB that make the fishes respond positive reaction to the feeding sound. 3) Lateolabrax japonicus and stephanolepis cirrhifer showed positive response and Fugu vermicularis showed little to the emitted feeding sound. 4) The fishes showed positive response to the sound until 5 minutes and then showed negative response, as the sound emitting succeed 10 minutes.

• 한국해양학회지
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• v.25 no.1
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• pp.26-35
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• 1990

Sound velocities and attenuation coefficients of marine surface sediments were calculated from insitu acoustic experiments on 4 nearshore areas off Pohang, Pusan Yeosu, and Kunsan around the Korean Peninsula. The relationship between these values and physical properties of sediments was examined and attenuation mechanism was analysed using the estimated gas content. Sound velocities and attenuation coefficients ranging from 1470 to 1616 m/sec and 0.0565 to 0.6604 dB/kHz-m, respectively, are well related to sediment types. The attenuation coefficient is maximum in coarse silts, and the sound velocity increases with density. The gas content estimated less than 8 ppm increases with the decreasing sediment grain size. When the sediment size is greater than fine sand, sound attenuation is mostly due to friction losses, and probably negligible viscous loss remains unchanged with the varying physical properties of sediments. The maximum attenuation in coarse silts result from both friction loss and cohesion of finer sediments between the contacts of silt grains. The cohesion begins to be the dominant dissipative process with decreasing grain size from medium and fine silts.

• 한국해양학회지
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• v.20 no.2
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• pp.10-21
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• 1985

The sound velocity (compressional wave) and attenuation coefficient in the marine surface sediments in the nearshore areas off the Pohang, Pusan, Yeosu and Kunsan were investigated in terms of the geotechnical properties of the marine surface sediments in the water depth range of 10-50 meters. The marine surface sediments in the study areas are variable, that is, sand to clay. Due to the various four different study area, the sound velocities and attenuation coefficients in the surface sediment facies vary 1,44m/sec to 1,510m/sec in velocity and 0.82dB/m to 3.70dB/m in coefficient respectively. In fact, the sound velocity increases with increasing of density and mean grain sizes of the sediments, and however, with decreasing of porosith. The correlation equations between the sound velocith and geotechnical properties of mean grain size, density, and porosity were expressed as the following: Vp=1512.28406-9.16083(Mz)＋0.20795(Mz)$\^$2/, Vp=1876.15527-597.50397(d)＋210.48375(d)$\^$2/, Vp=1559.47217-2.09266(n)$\^$2/. where Vp is sound velocity, Mz is mean grain size, d is density, and m is porosity, respectively. However, the relationship between the attenuation and geotechnical properties were different from that of sound velocity and geotchnical properties. Furthermore, the correlation equations between attenuation coefficient and geotechnical properties were expressed as the following: a=1.85217＋0.67197(Mz)-0.09035 (Mz)$\^$2/, a=48.87859＋58.21721(d)-16.3.143(d)$\^$2/, a=2.06765＋0.07215(n)-0.00111(n)$\^$2/, where a is attenuation coefficient. The high attenuation appeared in the silty sand through fine sand facies in sediment and k values in these facies were in the range of 0.86 to 0.89 dB/m/KHz.