• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.3
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• pp.204-213
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• 2010

Test fishing was carried out using six kinds of different mesh sizes (20, 22, 24, 28, 35, 40mm) for springnet-pot to study bycatches according to the mesh size and catches survey was done for another one (mesh size : 22mm, entrance round : 350mm) in Geo-je & Tong-young waters of Korea. On the first sea experiment, it was thought that suitable mesh size of spring-net-pot catching conger-eel over 35cm with decreasing the catches of conger-eel (Conger myriaster) below 35cm was 24mm. On the second sea experiment, commercial catches were crabs (Charybdis bimaculata), octopus minor (Octopus variabilis) and others including conger-eel, and catches proportion was 60% of total catches weights. There was no big difference for the monthly catches. Self-consumption catches were 9 species including conger-eel below 35cm holding 50% of catches in the side of weights. There were 40% of bycatches for the catches weights and 63% for catches numbers in the 22mm mesh size of spring-net-pot having entrance round over 140mm. It showed that 50% of catches weights were discarded.

• The Journal of Engineering Geology
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• v.12 no.4
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• pp.439-457
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• 2002

Sping waters at 60 sites and groundwaters at 6 wells in Mts. Geumjeong and Baekyang area were investigated for measuring nine physicochemical components (temperature, pH, Eh, EC, TDS, DO, salinity, alkalinity and discharge rate). The pH of spring waters ranges from 5.06 to 8.38, alkalinity from 7.93 to 102.21 mg/ㅣ, electrical conductance from 9.5 to $270{\;}\mu\textrm{s}/cm$, Eh from 64.2 to 685.9 mV, DO from 4.57 to 12.13 mg/l, and the discharge rate from 4.26 to 182.2 ml/s. General statistics was carried out to analyze statistical characteristics of those components. To compare the components with one another, regression analyses were carried out. And the components of spring waters were compared to those of groundwaters. Kriging was used to estimate the spatial variation of DO, pH, Eh, EC, alkalinity and discharge rate in the study area. The kriged isopleth maps were made using normalized kriged values to find anomalies of the physicochemical components and to compare anomalies of different components.

• Ocean and Polar Research
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• v.41 no.3
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• pp.135-145
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• 2019

We investigated the mass occurrence of the salp Salpa fusiformis during spring in the southern waters of Korea and the northern East China Sea. Abundance of S. fusiformis and dominant taxonomic groups including copepods, ostracods, euphausiids, and appendicularian was examined along with environmental factors (e.g., temperature, salinity, and chlorophyll-a concentration). The abundance of S. fusiformis at 27 stations ranged from 0 to $183\;inds\;m^{-3}$. Both aggregate and solitary forms of S. fusiformis occurred with a mean abundance of $62\;inds\;m^{-3}$ and $4\;inds\;m^{-3}$, and mean body length of 6.5 mm and 15.4 mm, respectively. Redundancy analysis showed that the abundance of S. fusiformis was negatively correlated with chlorophyll-a concentration, indicating the intensive grazing impact of S. fusiformis on phytoplankton. While the abundance of S. fusiformis increased, the species diversity of zooplankton community decreased. The abundances of total copepods and the dominant copepod species (e.g., adults and/or copepodites of Paracalansus parvus s.l., Calanus sinicus, Oithona similis, and Corycaeus affinis) also decreased with the increase of S. fusiformis abundance. However, the abundance of ostracods, euphausiids, and appendicularians was not affected by the mass occurrence of the salps. These results suggest that the mass occurrence of S. fusiformis in spring could negatively affect ecosystem conditions by changing trophodynamics in the zooplankton community.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.30 no.3
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• pp.142-149
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• 1994

In order to investigate the environmental properties of set net grounds located in the coastal waters of Yeosu. The current in the vicinity of set net grounds was observed by drogue and current meter in 1990 and 1992. The results obtained are summarized as follows: The direction of tidal current at the north enterance of Yeosu bay was southerly in ebb and northwesterly in flood without the distiction of the neap tide and the spring tide. In spring tide the maximum Velocity of the tidal current was 68 cm/sec in ebb and 66 cm/sec in flood. In neap tide the maximum velocity of the tidal current was 37 cm/sec in ebb and 35 cm/sec in flood. And so the direction of residual current was the south ward mainly and 21 cm/sec. The direction of tidal current at set net fishing grounds was southwesterly in ebb and westerly or northwesterly in flood. Regardless of the distinction of neap and spring. The maximum velocity of the current in spring tide was 50 cm/sec in ebb and 40 cm/sec in flood and that in neap was 28 cm/sec in ebb and 25 cm/sec in flood. In spring tide the speed vector along the major axis of semidiurnal tide component was three times as large as diurnal tide. In neap tide, however, the speed vector was about 50% less then that in spring tide, and the semidiurnal tide and diurnal tide were equal in the size of current ellipse and the direction of major axis. The sea area had a southwesterly residual current. 11 cm/sec in spring tide and 7 cm/sec in neap tide. According to the result of drogue tracking, the vicinity of set net fishing ground had a southerly residual current which formed in Yeosu Bay and a weak westerly residual current toward Dolsando from Namhedo. Therefore, set net fishing ground in coastal water of Yeosu was distributed in boundary of inner water which formed from Seamjin river and offshore water supplied from the vicinity of Sorido and Yochido.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.3
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• pp.36-45
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• 2006

By analyzing the sea surface temperature (SST), chlorophyll ${\alpha}$, zooplankton and Orview/SeaWiFS satellite data in the Korean Waters from 1999 to 2001, we studied the seasonal and annual variation of chlorophyll ${\alpha}$ concentration and zooplankton biomass. Sea surface temperature was fluctuated with the typical seasonal variation in the waters of temperate zone. Chlorophyll ${\alpha}$ concentration and zooplankton biomass were high in spring and autumn. Year to year fluctuations on annual averaged chlorophyll ${\alpha}$ concentrations in Korean Waters in the spring from 1999 to 2001 were decreased continuously. On the other hand, the estimated chlorophyll ${\alpha}$ concentrations derived from SeaWiFS ocean color data were lower than the measured sea surface chlorophyll a in the Korean Waters.

• Journal of Environmental Health Sciences
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• v.14 no.1
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• pp.33-38
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• 1988

Natural mineral water is generally quite different from ordinary drinking water due to its original nature and various properties. The complexity of natural mineral water requires, therefore, not only to identify its nature and proper characteristics, but also to classify them by a reasonable scientific basis of comparison. The study was concentrated on a possible classification technique to natural mineral waters by their constitutions and physico-ehemical properties. The classification was carried out by the computation of such numerical parameters as ionic equivalent percentage, electrolytic conductance or mobility, ionic molecular weight, molecular concentration, equivalent conductivity and degree of ionization in consideration of the determinative criteria as follows -particular single element or molecule -major components of natural waters as bicarbonate, sulphate, chloride,caloride, calcium, magnesium, and sodium -moleculat concentration related to blood osmotic pressure -water temperature at emergence from spring -contents of free carbon dioxide (CO2) -pH value of water -total dissolved solids or salts (NaCl) The results obtained proved out to be clearly distinguhhable from ordinary drinking water as far as concern natural mineral water as an example on the subject -simple water -bicarbonate-predominating water -cold spring -carbonated-non gaseous water -weak alkaline water -non saline water Putting these various results together, the sample turned out to be a kind of natural mineral water that can be used as a drinking water if microbiologically safe.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.2
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• pp.120-128
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• 2003

Fishes were caught by a set net in the coastal waters off Yosu, Korea from April to October, 2001, and seasonal variation of abundance and species composition were studied. Fifty two species were identified as fish $(89\%)\;cephalopods\;(10\%)\;and\;crustaeans\;(1\%).$ Of the fishes Engraulis japonicus, Trachurus japonicus and Trichiurus lepturus were dominant species representing $64.1\%$ in total number of individuals. The number of species was high in spring and low in summer; number of individuals was high in spring and low in autumn. The diversity index (H') was 0.4-0.7 The abundance and species composition fluctuated seasonally. Occurrence of the various stages of fishes indicated that Scombia japonicus, T. japonicus and E japonicus utilized in the area as spawning ground, Conger myriaster larvae, Ammodytes personatus and Seriola quinqueradiata as nursery ground, and T. lepturus and Ilisha elongata as spawning and nursery grounds.

• Water for future
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• v.17 no.2
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• pp.72-79
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• 1984

This investagation was carried out by analyzing water types and measuring the environmetal isotopes (tritium and deuterium) for development of water resources and protection of ground waters from sea water intrusion. The water sample were taken monthly from April to June, 1983 from sixteen sites in the Cheju metropolitan area; three sea, three spring, and ten ground waters. The ground water in the midwest area of the city contained 20 TU of tritium and-46 per mille of deuterium, classified as the $NaHCO_3$ type of ground water, generally deep seated. The spring water and ground water in the southern part of the city contained 15 to of tritium and-39 per mile of deuterium, and appeared to the $CaHCO_3$ type of shallow ground water, easily affected 표 precipitation. The results of tritium and deuterium analyses showed that the ground water in the coastal area were not affected by sea water intrusion, although they changed from $NaHCO_3$ or $CaHCO_3$ type to NaCl type in May and June. It is concluded that the high Na and Cl content in those ground waters might come from municipal sewage. The sea water in the Yong-duam area was influenced by sping water.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.60 no.1
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• pp.9-17
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• 2024

In this study, the seasonal distribution was surveyed using acoustic in the coastal waters around nuclear power plants. Acoustic surveys were conducted in June, September, December 2022, and March 2023 in the coastal waters of Uljin-gun. According to the results of this study, zooplankton were distributed at the depths from 0 m to 50 m in the waters around nuclear power plants. Zooplankton appeared in summer (June), autumn (September), and spring (March). In the survey area, fish were distributed at the depths from 25 m to 190 m, appearing in the summer (June), autumn (September), winter (December) and spring (March). The SV of zooplankton appearing in the survey area ranged from -98.0 dB to -78.0 dB, and it exhibited a one-class in the frequency distribution of SV. The SV of fish appearing in the survey area ranged from -36.0 dB to -35.0 dB and -98.0 dB to -53.0 dB, and it exhibited two-class in the frequency distribution of SV.

• Korean Journal of Environmental Biology
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• v.21 no.4
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• pp.422-427
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• 2003

The spatio-temporal distribution of four coexisting acartiid species in two subgenera Acartiura (Acartia hongi and A. omorii) and Odontacartia (A. erythraea and A. pacifica) was examined at seven stations in the southwestern waters of Korea, between January to December 1998. A. hongi occurred dominantly in the northern regions from winter to spring while A. omorii predominated in the southern regions in spring and early summer when the more saline (> 33.0 psu) and high chlorophyll-$\alpha$ concentration water mass appeared. With the increase of temperature (> $20^{\circ}C$), however, both species disappeared and then replaced with A. erythraea and A. pacifica. A. erythraea (rare species), appeared in the middle regions where the high chlorophyll-$\alpha$ concentration ($3{\mu}g\; I^{-1}$) in the summer, while A. pacifica was abundant in all regions through summer and fall. It is suggested that the seasonal succession of the genus Acartia was subgenus-specifically affected by environmental factors such as temperature, salinity and chlorophyll-$\alpha$ concentration.