• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.44 no.4
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• pp.304-311
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• 2008

Patagonian toothfish(Dissostichus eleginoides) was investigated in the southeastern Atlantic Ocean during the period of 19 March to 7 July 2007 by commercial bottom longliners. The number of 116 hauls were carried out individually in this study area by two bottom longliners during 111 days. The total catches were 89,559kg(9.91kg/100hooks) and 66,758kg(7.38kg/100hooks), respectively. Most Patagonian toothfishes were caught on the $46-48^{\circ}S$, $6-11^{\circ}E$ of southeastern Atlantic Ocean. Patagonian toothfish comprised 67.01-92.49%(by weight) of the catches in the southeastern Atlantic Ocean. No Antarctic toothfish (Dissostichus mawsoni) was caught during the surveys. Patagonian toothfish was found throughout the experimental area, but the density was considerably greater in the layer of 1,300-1,900m, where 49.88% of the fishes were caught. Smaller fishes were generally distributed to the shallow waters and larger fish were more frequently caught with the depth. Mean size of Patagonian toothfish increased with depth of capture. Accordingly economically profitable fishing activities for the Patagonian toothfish fishery requires an understanding of the size distribution of the Patagonian toothfish by depth.

• Ocean and Polar Research
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• v.26 no.3
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• pp.501-506
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• 2004

The observational proxy estimates suggest that the North Atlantic overturning stream function associated with the North Atlantic Deep Water (NADW) production and outflow was substantially weaker during the last glacial maximum (LGM) than that observed under present conditions. The impact of the changes in overturning circulation on the glacial carbon budget is investigated using a box model. The carbon box model reveals that the atmospheric $CO_2$ concentration is more sensitive to change in the overturning circulation of the North Atlantic than that of the Southern Ocean, especially when North Atlantic overturning becomes weaker. For example, when the strength of the North Atlantic overturning circulation is halved, the atmospheric $CO_2$ concentration is reduced by 50ppm of that associated with the accumulation of $CO_2$ in the deep ocean. This result implies that a weaker North Atlantic overturning circulation may play an important role in the lowering of LGM atmospheric $CO_2$ concentration.

• Ocean and Polar Research
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• v.36 no.3
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• pp.225-234
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• 2014

The 2011 Tohoku earthquake triggered extremely destructive tsunami waves which propagated over the Pacific Ocean, Atlantic Ocean through Drake Passage and Indian Ocean respectively. A total of 10 tide-gauge records collected from the UNESCO/IOC site were analyzed through a band-pass digital filtering device to examine the observed tsunami characteristics. The ray tracing method and finite-difference model with GEBCO 30 arc second bathymetry were also applied to compare the travel times of the Tohoku-originated tsunami, particularly at Rodrigues in the Indian Ocean and King Edward Point in the Atlantic Ocean with observation-based estimates. At both locations the finite-difference model produced the shortest arrival times, while the ray method produced the longest arrival times. Values of the travel time difference however appear to be within tolerable ranges, considering the propagation distance of the tsunami waves. The observed tsunami at Rodrigues, Mauritius in the west of the Madagascar was found to take a clockwise travel path around Australia and New Zealand, while the observed tsunami at King Edward Point in the southern Atlantic Ocean was found to traverse the Pacific Ocean and then passed into the Atlantic Ocean through the Drake Strait. The formation of icebergs captured by satellite images in Sulzberger in the Antarctica also supports the long-range propagation of the Tohoku-originated tsunami.

• Mycobiology
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• v.49 no.2
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• pp.151-160
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• 2021

Despite recent studies, relatively few are known about the diversity of fungal communities in the deep Atlantic Ocean. In this study, we investigated the diversity of fungal communities in 15 different deep-sea sediments from the South Atlantic Ocean with a culture-dependent approach followed by phylogenetic analysis of ITS sequences. A total of 29 fungal strains were isolated from the 15 deep-sea sediments. These strains belong to four fungal genera, including Aspergillus, Cladosporium, Penicillium, and Alternaria. Penicillium, accounting for 44.8% of the total fungal isolates, was a dominant genus. The antiaflatoxigenic activity of these deep-sea fungal isolates was studied. Surprisingly, most of the strains showed moderate to strong antiaflatoxigenic activity. Four isolates, belonging to species of Penicillium polonicum, Penicillium chrysogenum, Aspergillus versicolor, and Cladosporium cladosporioides, could completely inhibit not only the mycelial growth of Aspergillus parasiticus mutant strain NFRI-95, but also the aflatoxin production. To our knowledge, this is the first report to investigate the antiaflatoxigenic activity of culturable deep-sea fungi. Our results provide new insights into the community composition of fungi in the deep South Atlantic Ocean. The high proportion of strains that displayed antiaflatoxigenic activity demonstrates that deep-sea fungi from the Atlantic Ocean are valuable resources for mining bioactive compounds.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.4
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• pp.556-566
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• 2014

Korean distant water tuna longline fishery commenced in 1966 in the Atlantic Ocean. Since then, it has become one of the most important fisheries of Korea. By early of 1970s, total amount of tuna caught in the Atlantic Ocean was the highest among other Korean distant water tuna fisheries, but has become minor since 1990s. The annual catch of tuna and tuna-like species by Korean tuna longline fishery in the Atlantic Ocean was about 1,900 mt in 2013. Bigeye tuna was the predominant species in species composition followed by yellowfin tuna, Albacore tuna, Blue shark and Swordfish. Korean distant water tuna longline fishery have mainly operated in the tropical area of the Atlantic Ocean ($20^{\circ}N{\sim}20^{\circ}S$, $20^{\circ}E{\sim}60^{\circ}W$), fishing ground was almost similar as in the previous years. The length frequency of major species (Bigeye tuna, Yellowfin tuna, Albacore tuna, Blue shark and Swordfish) were estimated. As the result of length (size) frequency data on main species caught by lonline fishery in the Atlantic Ocean, main length intervals of bigeye tuna caught in 2011, 2012 and 2013 were 120~125 cm, 160~165 cm and 130~135 cm, respectively. For yellowfin tuna, those were 125~130 cm, 150~155 cm, 145~150 cm and for albacore, 109 cm, 102 cm, 109 cm and 106 cm respectively. For swordfish caught in 2011, 2012 and 2013, main length intervals were 130~135 cm, 125~135 cm and 125~130 cm, respectively, and for blue shark, 195~200 cm in 2011 and 185~190 cm in 2012, 2013.

• Proceedings of the Korean Quaternary Association Conference
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• 2004.11a
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• pp.37-43
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• 2004

The response of the CCCma coupled climate model to the imposition of LGM conditions is investigated. The global mean SAT and SST decrease by about $10^{\circ}C$ and $5.6^{\circ}C$ in the coupled model. Tropical SST decreases by $6.5^{\circ}C$, whereas CLIMAP reconstructions suggest that the tropics cool by only about $1.7^{\circ}C$, although the larger tropical cooling is consistent with the more recent proxy estimates. With the incorporation of a full ocean component, the coupled model gives a realistic spatial SST pattern, capturing features associated with ocean dynamics that are seen in the CLIMAP reconstructions. The larger decrease of the surface temperature in the model is associated with a reduction in global precipitation rate (about 15%). The tropical Pacific warm pool retreats to the west and a mean La $Ni\tilde{n}a$-like response is simulated with less precipitation over the central Pacific and more in the western tropical Pacific. The more arid ocean climate in the LGM results in an increase in SSS almost everywhere. This is particularly the case in the Arctic Ocean where large SSS increase is due to a decrease in river discharge to the Arctic Ocean associated with the accumulation of snow over the ice sheet, but in the North Atlantic by contrast SSS decreases markedly. This remarkable reduction of SSS in the North Atlantic is attributed to an increase in fresh water supply by an increase in discharges from the Mississippi and Amazon rivers and an increase in P-E over the North Atlantic ocean itself. The discharges increase in association with the wetter LGM climate south of the Laurentide ice sheet and in South America. The fresh water capping of the northern North Atlantic results in a marked reduction of deep convection and consequently a marked weakening of the North Atlantic overturning circulation. In the LGM, the maximum overturning stream function associated with the NADW formation decreases by about 60% relative to the control run, while in the Southern Ocean, oceanic convection is stronger in the LGM due to reduced stratification associated with an increase in SSS and a decrease in SST and the overturning stream function associated with the formation of AABW and the outflow increases substantially.

• Ocean Systems Engineering
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• v.3 no.1
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• pp.1-8
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• 2013

This brief study aims at providing a model to predict the time of service of a cracked bar in corrosive environment, in view of both the fracture mechanics and elastic failure criteria. Dolinskii's assumption on the relationship between stress and the corrosion rate is adopted. It is superimposed with fracture mechanics consideration. A comparison between the time of service of a cracked bar and that of a uniform bar is provided.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.2
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• pp.208-216
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• 2014

In case of any coastal ocean near the mouth of huge rivers, low salinity water can be formed due to its large amount of freshwater discharge. For the acoustic analysis on the low salinity environment, some oceanographic data of the East China Sea and the Atlantic Ocean were collected through KODC (Korea Oceanographic Data Center) and NODC (National Oceanographic Data Center) online service. In this paper, the T-S gradient diagram is introduced to show a relation between the gradients of temperature and salinity in view of acoustic surface channel formation. Existence of haline channel, quantitative contribution of gradients of salinity and temperature, effectiveness of the channel formation can be known by the T-S gradient diagram. After applying the collected data into the diagram, tropical regions of the Atlantic Ocean show strong haline channel due to its nearly invariant temperature and drastic change of salinity with depth. The averaged transmission loss in the channel is about 5.7 ~ 7.5 dB less than that out of the channel by the results of acoustic propagation model (RAM: Range independent Acoustic Model). On the other hand, the East China Sea and temperate region of the Atlantic ocean have weaker haline channel with less difference of the averaged transmission loss between in and out of the channel as 3.2 ~ 6.0 dB. Although data samples used in this study have limitation to represent the general physical structures of the three ocean regions, the T-S gradient diagram is shown to be useful and acoustic field affected by low salinity environment is investigated in this study.

• Ocean Systems Engineering
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• v.1 no.2
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• pp.121-130
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• 2011

One of the prevailing models that describe the stress corrosion is represented by an exponential dependence between rate of corrosion and stress, suggested by Gutman, Zainullin and Zuripov. This study revisits the exponential model and derives analytical expressions for the structures' durability which is postulated as the time for stress level to reach its yield value. Comparison is conducted with other possible models, namely with linear, quadratic or cubic cases.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.4
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• pp.517-525
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• 2021

Trawl fishing is a major concern worldwide, and there is considerable debate about its impact on marine ecosystems. In this study, we used the vessel monitoring system (VMS) data collected in the southwest Atlantic Ocean from 2016 to 2019 to estimate the fishing effort and trawled area. Spatial distribution of trawl activities according to the latitude and longitude and the hotspots where fishing was concentrated each year were identified. Trawling activities of the Korean vessels were mainly distributed between 40-52°S and 56-63°W. The species caught during the fishing period comprised five Cephalopoda, three Chondrichthyes, ten Osteichthyes, and other fish. The Argentine hake Merluccius hubbsi and Argentine shortfin squid Illex argentinus were the dominant species in the catch.