• 한국해양학회지
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• v.19 no.2
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• pp.153-162
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• 1984

This study was conducted to interpret the relations between the polychaete community and its environments in Kwangyang Bay during July, 1982. The type of sediments in the study area varies from sand to clay and the organic content obtained by ignition was in the ranges of 0.3% to 15.4%. The polychaetes which occurred at 25 stations comprised 70 species representing 63 genera and had an average density of 490 animals/m$\^$2/. The most abundant species were Lagis bocki (20%), Lumbrineris longifolia (10%), Chohe teres (7%), and Sternaspis scutata (5%). The polychaete populations show the highest density in muddy sand sediments and have a tendency to decrease their abundance in finer sediments such as bud and clay. The individual numbers of each feeding type show the same tendency. Kwangyang Bay consists of three distinct characteristic communities, representing different physical and biological factors: delta community, muddy flat community and channel community. Delta community has very poor organisms and seems to be determined by physical factors such as tidal current, and by sediment conditions and seems to be determined by physical factors such as tidal current, and by sediment conditions and by the food availability. Muddy flat community shows more diverse and higher abundance than delta community but seems to be impoverished by the stress of oxygen deficiency in sediments. Channel community has the highest density in the study area and comprises more various feeding types. This is probably due to the supply of allochthonous materials from the Seomjin River and offshore as food, the heterogeneous sediments and some biological interactions within habitats.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.4
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• pp.291-298
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• 2024

As an important fishing ground in the southern coast of Korea, Jinhae Bay is characterized by a high level of fisheries production. However, its marine-ecosystem has shifted owing to environmental changes such as industrial development and high water temperatures over the decades. This study analyzes the fisheries production, discards, mean trophic level, and fishing-in-balance index using annual fishing data from five regions surrounding Jinhae Bay for the period 2005-2022, as well as using additional forecasting trends by 2027 using ARIMA (Auto Regressive Intergrated Moving Average). The results shows, that the production in Goseong will decrease continuously by 2027, as compared with that in other areas. Additionally, byproduct management is considered necessary in Tongyeong. For the marine-ecosystem index, Tongyeong indicates stable catch ratio of large fish species and a fishing-in-balance exceeding 0. Finally, the annual catch variation for six pelagic fish species in Jinhae Bay by 2060 is estimated based on the IPCC climate-change scenario, in which the recent low level that decreased to approximately 20 thousand ton in early 2020 is projected to recover to approximately 40 thousand ton in the 2020s and 2040s, followed by an incremental decline by 2060.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.3
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• pp.177-185
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• 2012

Wave field measurements were made over a period of 18 days to study the spatial distribution of incident wave on seaweed tarm field around Gumil-up Sea, Wando, Korea. These measured data were compared with data from the Geomun-do ocean weather/wave observation buoy. A numerical simulation model that combined the offshore design wave with the seasonal normal incoming wave was used to study the incident wave distribution surrounding a seaweed farm. The results are summarized as follows. (1) On-site wave measurements showed that the major relationship between maximum and significant wave height was $H_{max}=1.6H_{1/3}$. (2) Offshore incident wave energy reaching the coast was greatly influenced by the wind direction. A north wind reduced the incident wave energy and a south wind increased it. (3) The calculated maximum wave height under the design wave boundany conditions was in the range of 4~5 m and the reduction in the incident wave height ratio ranged from approximately 38.1% to 47.6% at Gumil-up Sea. Under normal wave conditions, the maximum wave heights were 3.6~4.0 m in summer and 2.3~2.7 m in winter while the reduction in the incident wave height ratio was about 41.8% to 49.1%. (4) The sea state in the southern area of Gumil-up was the most affected by ocean waves, whereas the sea state in the northern area was very stable. The significant wave ratio in the south was about six times that in the north.

• Korean Journal of Food Science and Technology
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• v.43 no.4
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• pp.464-468
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• 2011

Halocynthia roretzi is one of the most important cultured marine species on the southern coast of Korea. Samples were extracted using methanol (ME), ethanol (EE) and water (WE) to evaluate the antioxidant activities and antilipase activity in Halocynthia roretzi extracts. Antioxidant potentials of the samples were determined by poly-phenol content, flavonoid content, free radical scavenging activity, reducing potential, and chelating activity. The ME showed significant scavenging activity (1176 ${\mu}g/mL$ IC50 for DPPH, and 895 ${\mu}g/mL$ IC50 for ABTS assay). The IC50 for lipase inhibition activity was 12,021, 6,004, and 14,979 ${\mu}g/mL$ in the ME, EE, and WE, respectively. In conclusion, Halocynthia roretzi extracts exhibited antioxidant activities and anti-lipase activity. These results suggest that Halocynthia roretzi extracts can be potentially used as a source of antioxidant and antiobesity agents.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.1
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• pp.35-45
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• 2002

Seasonal quantitative van Veen grab sampling was conducted to characterize the composition and structure of the benthic polychaete community inhabiting the shellfish farming ground of a coastal bay system of Jiniu Bay (Korea). A total of 132 polychaete species were identified and the polychaetes accounted for about $80\%$ of overall abundance of benthic animals. There was little significant seasonal difference in densities (abundances) of polychaetes, Maximum biomass was obseued in summer (August) and minimum value was recorded in winter (February) and spring (May). Conversely, diversity and richness were lowest in summer, indicating a seasonal variability in the polychaetous community structure, The cluster analysis indicated that such a seasonal variability resulted mainly from the appearance of a few small, r-selected opportunists in spring and the tubiculous species of the family Maldanidae in summer. On the other hand, several indicator species for the organically enriched environments such as Capitelia capitata, Notoniashs Jatericeus and hmbrineris sp. showed high densities during all the study period. Density and biomass of univariate measures of community structure were significantly lower in the arkshell-farming ground of the southern area than in the non-farming sites of the bay, A similar general tendency was also found in the spatial distributions of species diversity and richness. Principal component analysis revealed the existence of different groups of benthic assemblages between the arkshell-farming ground and non-farming sites, The lack of colonization of r-selected opportunists and/or tubiculous species in the former ground seemed to contribute to the spatial differences in the composition and structure of the polychaetous communities. Although finer granulometric composition and high sulfide concentration in sediments of the arkshell-farming ground and low salinity in the northern area were likely to account for parts of the differences, other environmental variables observed were unlikely. The spatial distribution of polychaetes in Jiniu Bay may be rather closely related to the sedimentary disturbance by selection of shells for harvesting in spring.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.3
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• pp.483-494
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• 2019

From the cosmopolitan superiority of the as the first world map completed in 1402 with surprisingly detailed images and contents on the Africa Continent it is reasonable to think that the Koreans in early fifteen century were already with highly up-to-date perspectives on the universe and world history and cultures. However, some 490 year later the first phytohydrographic plankton investigation in the neritic seas of Korea was performed by a Japanese company with sampling points covering from Tokyo Bay through Jeju neritic waters to Shanghai estuary, which was in turn preceded by the first oceanographic investigation other than the simple mapping Koreans seas by using two French sailboats. The first phytohydrographic plankton investigation in Korean seas were behind the world first oceanic plankton exploration, the German Plankton Expedition, by 25 years. Starting from the oceanographic investigation including phytohydrographic samplings in the whole Yellow Sea in 1915 the full-scale phytohydrographic plankton studies were tried in Korean seas which is well represented by the 1921 oceanographic investigation on the whole East Sea with 80 sampling stations. In 1932 two separate oceanographic investigations followed, one in the East Sea where 78 stations from Busan to southern Sakhalin Island were simultaneously visited by 50 research vessels for the physical, chemical, and biological oceanographic studies, and the other one in southern coast and western East Sea of Korea where ocean current observation as well as plankton sampling were made in 120 stations to understand the relationship between the ocean current and plankton distribution in the region. In 1933-1934 more intensified investigations on phytohydrography were carried out particularly in the East Sea as an integral part of the basic marine ecosystem studies for the Myeong-Tae (Alaska Pollock) resources estimation. Scientists' attitude for the marine investigation and research activities seemed to be almost unchanging even to the year 1943, which could be reflected by the fact that publication of the results from the investigations performed in 1945 were finally done in 1967 at Tokyo. Some 70 years later from the mid-twenty century we might be standing on the turning-point of "need to be prepared" for the new era of changing paradigm by reviewing, archiving, and analyzing the prior information big data from the previous ocean observation and biohydrographic investigations. At the same time each professional societies for the above mentioned sciences might trigger a continuous project to reorganize and update the records on related bibliography and its history every 30 years.

• Journal of the Korean earth science society
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• v.41 no.6
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• pp.617-629
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• 2020

Sea surface temperature (SST), which plays an important role in climate change and global environmental change, can be divided into skin sea surface temperature (SSST) observed by satellite infrared sensors and the bulk temperature of sea water (BSST) measured by instruments. As sea surface temperature products distributed by many overseas institutions represent temperatures at different depths, it is essential to understand the relationship between the SSST and the BSST. In this study, we constructed an observation system of infrared radiometer onboard a marine research vessel for the first time in Korea to measure the SSST. The calibration coefficients were prepared by performing the calibration procedure of the radiometer device in the laboratory prior to the shipborne observation. A series of processes were applied to calculate the temperature of the layer of radiance emitted from the sea surface as well as that from the sky. The differences in skin-bulk temperatures were investigated quantitatively and the characteristics of the vertical structure of temperatures in the upper ocean were understood through comparison with Himawari-8 geostationary satellite SSTs. Comparison of the skin-bulk temperature differences illustrated overall differences of about 0.76℃ at Jangmok port in the southern coast and the offshore region of the eastern coast of the Korean Peninsula from 21 April to May 6, 2020. In addition, the root-mean-square error of the skin-bulk temperature differences showed daily variation from 0.6℃ to 0.9℃, with the largest difference of 0.83-0.89℃ at 1-3 KST during the daytime and the smallest difference of 0.59℃ at 15 KST. The bias also revealed clear diurnal variation at a range of 0.47-0.75℃. The difference between the observed skin sea surface temperature and the satellite sea surface temperature showed a mean square error of approximately 0.74℃ and a bias of 0.37℃. The analysis of this study confirmed the difference in the skin-bulk temperatures according to the observation depth. This suggests that further ocean shipborne infrared radiometer observations should be carried out continuously in the offshore regions to understand diurnal variation as well as seasonal variations of the skin-bulk SSTs and their relations to potential causes.

• Korean Journal of Heritage: History & Science
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• v.55 no.3
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• pp.132-150
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• 2022

Designated as a national intangible cultural asset, the fish weir is a traditional fishing method and was a leading fishing tool in Korean coastal fishery. As the littoral sea area fishing vessel fishery developed since the 1970s, traditional fishing methods including fish weirs began to decline. The fish weir has been passed down in the form of tools such as fish weirs, stone weirs, and bamboo weirs. In Namhae-gun and Sacheon City in Gyeongsangnam-do, anchovies are caught using bamboo weirs. A basic bamboo weir consists of a fish trap(balgong), a space where fish gather together, and a V- or U-shaped wooden fence(halgaji) that helps fish come inside the fish trap. Its fishing method is to catch fish that have come to the coast during high tide alongside those are stuck inside fish traps(balgong) with nets or scoop nets. This paper examined the process of passing down traditional fishing methods through a comparative analysis of the bamboo weir structures and fishing methods in the Namhae and Sacheon regions. First, the historical process of assembling the current bamboo weir structure was analyzed. The bamboo weir, a fishing tool, appears to have combined the features of past weirs and fish weirs based on the Jijok Strait and Samcheonpo Strait. Next, this paper examined the structure and fishing method of the two types of bamboo weirs made with a circular or square fish trap(balgong) where fish gather. Through this analysis, this study examined the lives of fishermen who have adapted to their natural environment and actively utilized obtainable resources(materials), and then changed the traditional fishing method of bamboo weirs and developed them into an appropriate technology. Lastly, a new value attributed to anchovies caught using bamboo weirs was analyzed. This new value extracted from better bamboo weir anchovies works as a mechanism to uphold the tradition of anchovy-catching bamboo-weir fishing, which produces a smaller amount of anchovies compared to other methods of anchovy fishing. In this way, bamboo weir fishing has been passed down as a result of its differentiated aspect of producing better anchovies than those produced with other fishing methods, as well as the historical aspect of it being a traditional fishing method.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.2
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• pp.67-85
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• 2007

A three-dimensional hydrodynamic model with the fine grid is applied to simulate the barotropic tides, tidal currents, residual currents and salinity dispersions in the Yellow Sea and the East China Sea. Data inputs include seasonal hydrography, mean wind and river input, and oceanic tides. Computed tidal distributions of four major tides($M_2,\;S_2,\;K_1$ and $O_1$) are presented and results are in good agreement with the observations in the domain. The model reproduces well the tidal charts. The tidal residual current is relatively strong around west coast of Korea including the Cheju Island and southern coast of China. The current by $M_2$ has a maximum speed of 10 cm/s in the vicinity of Cheju Island with a anti-clockwise circulation in the Yellow Sea. General tendency of the current, however, is to flow eastward in the South Sea. Surface residual current simulated with $M_2$ and with $M_2+S_2+K_1+O_1$ tidal forcing shows slightly different patterns in the East China Sea. The model shows that the southerly wind reduces the southward current created by freshwater discharge. In summer during high runoff(mean discharge about $50,000\;m^3/s$ of Yangtze), low salinity plume-like structure(with S < 30.0 psu) extending some 160 km toward the northeast and Changjiang Diluted Water(CDW), below salinity 26 psu, was found within about 95 km. The offshore dispersion of the Changjiang outflow water is enhanced by the prevailing southerly wind. It is estimated that the inertia of the river discharge cannot exclusively reach the around sea of Cheju Island. It is noted that spatial and temporal distribution of salinity and the other materials are controlled by mixture of Changjiang discharge, prevailing wind, advection by flowing warm current and tidal current.

• Journal of Aquaculture
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• v.5 no.1
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• pp.69-79
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• 1992

The muscle extracts of the ascidian, Halocynthia roretzi cultured for two and three years old on the southern coast near Chungmu and the eastern coast near Pohang of Korea, were analyzed for extractive nitrogen (EN), free amino acids (FAA), combined amino acids (CAA), nucleotides and related compounds (NRC), quaternary ammonium bases and guanidino compounds using specimens collected in February 1989 and in April 1989, and compared for those contents with each other. As for the amount of EN, no remarkable difference was found between two- and three-year-old samples collected at St. 1 in the spring and winter seasons, while at St. 2 in the spring season the two-year-old sample was distinctly lower than the three-year-old one. Taurine, proline, glutamic acid, glycine and alanine were the major FAA in every sample. The amount of taurine, the most prominent FAA, was higher in three-year-old sample than in two-year-old one regardless of sampling station and season. Most of the other major FAA showed a similar tendency to EN at both sampling stations in both seasons. Adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP), adenosine 5'-monophosphate (AMP), inosine 5'-monophosphate (IMP), inosine (Ino) and hypoxanthine (Hyp) were detected in all the samples and ATP, ADP and AMP were the major ingredients. The amounts of total NRC were in parallel with those of EN and total FAA. As for the contents of betaines, two- and three-year-old samples collected in the winter season exhibited a great discrepancy each other, the former being clearly lower than the latter, but no remarkable difference was observed between two samples of two groups in the spring season. In proximate composition of the muscles, the two-year-old sample was considerably higher in moisture content and lower in protein and glycogen contents than the three-year-old one at St. 2 in the spring season. The large discrepancies observed between two- and three-year-old samples from St. 2 seems to be attributable to the difference in size of samples rather than to the difference in age.