• Korean Journal of Ichthyology
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• v.19 no.4
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• pp.378-386
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• 2007

To study the composition of the developmental stages of Maurolicus japonicus eggs distributed in the western Korea Strait, we investigated the water temperature, salinity, eggs and larvae in December 2002. The Korea Strait Bottom Cold Water (KSBCW) lower than $10^{\circ}C$ was found in off the Ulsan and Busan where M. japonicus eggs were the most abundant. The composition of the developmental stages of M. japonicus eggs at each station were composed of 37.7~89.5% in the first stage, 8.5~37.8% in the middle stage and 0.0~24.7% in the last stage respectively. In the southern area where the KSBCW appeared, the first stage eggs occupied 73.3~89.5%. The high percentage of the first stage eggs indicated that the eggs should be transported by the cold water lower than $10^{\circ}C$ from the Ulleung Basin in the East Sea. In the northern area where the KSBCW was not found, the first, middle and last stage eggs were composed of 37.5%, 37.8% and 24.7% respectively. The ratios of middle and last stage eggs were much higher than those in the southern area with the KSBCW, which implies that the eggs are recruited into the northern area from the southern area with the KSBCW by the Tsushima Warm Current. The pre-larvae found only in the middle and northern part of the study area would be hatched during the transport of eggs from the southern area with the KSBCW by the Tsushima Warm Current.

• 한국해양학회지
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• v.20 no.3
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• pp.37-54
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• 1985

A description of the "phytohydrography" in the southwestern waters of the East Sea is given from concurrent measurement of temperature, chlorophyll-a, nutrients, and phytoplankton and also from the calculated primary production during the two cruises in May and October, 1984. Past history of water mass is relatively well reflected in the distribution of phytoplankton species, but such a reflection is rarely shown in the distribution of physical and chemical parameters in general. Upper layer of the waters around Ul-gi and Gampo is typically characterized by the high chlorophyll-a, high primary production, and low nanofraction ratio due to the continuing supply of nutrients from the nutrient-rich cold water underneath. Water of Tsushima current shows poor standing crop in terms of cell numbers and chlorophyll-a concentrations, extremely high nanofraction ratio, and very low primary production. The overwhelming importance of the nanofraction is confirmed in phytoplankton cell numbers, chlorophyll-a concentration, and possibly enough in primary production. This emphasizes the exceptionally strong inflow of warm water into the study area from south among all the waters around the whole Korean peninsula.

• 한국해양학회지
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• v.18 no.1
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• pp.73-83
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• 1983

To serch the origin of the cold water mass along the east coast of Korea its characteristics are inrestigated based upon Cooperative Study of Kuroahio and Fisheries Research and Development Agency data. In the southwestern part of the Japan Sea the North Korean Cold Water sinks at the front and flows southwards on top of the Japan Sea Proper Water. it is found that the sunken North Korean Cold Water il high in the content of dissolved oxygen and less saline compared with the Japan Sea Proper Water. It is highly likely that the cold water mass off the Jugbyeon-Chuksan coast in summer il the North Koreah Cold Water and not upwelled Japan Sea Proper Water. It os shown that the Notth Korean cold Water Flows strongly in summer and its scuthern limit is generally off Chuksan-Janggigab and occasionally off Gampo as observed in 1973.

• 한국해양학회지
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• v.28 no.3
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• pp.241-258
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• 1993

To investigate the sedimentary environments on the coastal areas of Imja to Nakweol islands which show very complex shorelines and several zonal sand ridges in NE-SW direction, southwestern coast of Korea, a total of forty samples were taken by a grab sampler and sedimentological and micropaleontological studies on those samples were carried out. The present study area are classified into muddy sandy gravel, sand, city sand, sandy silt and silt facies. With statistical moment parameters such as mean, sorting, skewness and ketosis for the sediments in the study area, the sediments are generally categorized as shallow sedimentary facies. The characters that are observed in quartz grains among the sandy sediments of the study area imply the existence of high energy environments, temporal exposures in atmosphere and the mixing of clastic sediments of the several different origins. In the sediments of the study area, one genera belonging to six silicoflagellata species and five genera belonging to five nannoplankton species were detected. On the basis of the micro-organism assemblage, the study area seems to be influenced by active reworking dominantly under warm water masses. In addition, organic matter ad carbonate contents in the sediments did not show a definite relation with the occurrences of the micro-organisms in the study area.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.179-187
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• 2018

In order to understand the flow of currents around Aphae Island and the surrounding Archipelago, the numerical model experiments on tidal currents and tide-induced residual currents were carried out. Dominant semidiurnal tidal currents have a reversing form and flow along the narrow channels of the archipelago. During periods of flood, currents flow from the west of Hwawon Peninsula to the archipelago to the northwest together with the currents flowing from the channels at Palgeum Island to Amtae Island and Amtae Island to Jeung Island. Ebb currents flow from the northwest archipelago to the channel of Amtae Island and Jeung Island as well as Amtae Island to Palgeum Island, further flowing south between Palgeum Island and Hwawon Peninsula. Flood currents are separated from east and west at the southern coast of Aphae Island, but flow south from both the west and east of Aphae Island to the channel found between Palgeum Island and Hwawon Peninsula at ebb. Flow speed is high between Amtae Island and Aphae Island where the flows meet and join. Lee wakes or topographical eddies are formed around the islands due to the high speed of the currents flowing along the narrow channel in the archipelago, manifesting as a tide-induced residual current. A weak cyclonic wake and anti-cyclonic eddy both exist at the west and northwestern coast of Aphae Island individually. The speed of the tide-induced residual current become slow on account of the wide littoral zone at exists around Aphae Island.

• Journal of Environmental Impact Assessment
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• v.28 no.5
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• pp.457-470
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• 2019

This study aims to present the characteristics of marine physics, water quality, and sediment quality around offshore wind farm near the Gochang and Buan sea areas through the analysis of monitoring data. The relationships between suspended solid and wave height as well as suspended solid and flow velocity were analyzed. We found that Correlation Coefficient values of 0.61~0.69 between wave height and suspended solid, and suspended solid concentration reaches 75 mg/L or higher when wave height of more than 1m occurred in the spring (1 month). The water quality index (WQI) was used to identify the status of the water quality in the study area. Most of the measured points were rated first grade (very good). The variation of chlorophyll-a was relatively hight compared to the other criteria, indicating that it is a major factor affecting the quality index. In the sediment column, all heavy metals were detected below the Threshold Effects Level(TEL), and ignition loss and grain size show a positive correlation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.2
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• pp.187-193
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• 2017

This study evaluated tidal stream energy resources according to tidal flow properties around Uido off the west coast of, Jeollanam-do, South Korea. A feasibility study was first carried out through the collection of bathymetry data and tidal phase information. For this simulation, a depth-averaged 2D ADCIRC (Advanced Circulation) model for real sea situations was applied to a Finite Element Method (FEM) approach for tides given the variation of tidal current speed. Hydrodynamics were simulated with 4 major tidal constituents (M2, S2, K1, and O1) after setting up 4 observation points. From the real depth-averaged model simulation results, it was found that the spring tide Higher High Water (HHW) and tidal current speed values at the 4 observation points were about 2.2 m and 1.33 m/s, respectively. The ADCIRC model results were analyzed with reference to the Korea Hydrographic and Oceanographic Agency's (KHOA) observed data for verification. Furthermore, using topographical characteristics via the Tidal Flux Method (TFM), tidal energy density distribution was calculated, indicating a maximum tidal energy density of about $1.75kW/m^2$ for the 5 assessment areas around Uido. The tidal energy density was evaluated with consideration given to topographical characteristics as well as tidal elevation and tidal current speed to determine an optimum tidal farm candidate.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.30 no.3
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• pp.103-113
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• 2018

Tide-surge characteristics of the West/South domestic coasts were analyzed with a tool of EST (empirical simulation technique). As a result, stations of Incheon, Gunsan, Mokpo and Busan are categorized as tide-dominant coasts, while Yeosu, Tongyoung and Busan are as surge-dominant coasts. In the tide-dominant coasts, extreme sea level of less than 50-yr frequency is formed without typhoon-surge, while only 10-yr extreme sea level is formed in the surge-dominant coasts. As the results of casual condition of extreme sea level formation considering the relative degree of surge on tide, the regional characteristics were detected also. Three methods for estimating the design tide level were compared. The AHHW method shows an unrealistic outcomes of the concern of over estimate design. Furthermore, the probability distribution function method has been concerned as causing missing data if a huge typhoon occurs in a neap tide or a low tide. To cope with these drawbacks, the applicability of the EST method is proved to be suitable especially in tide-dominant coasts.

• Korean Journal of Ecology and Environment
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• v.54 no.3
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• pp.229-239
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• 2021

Thamnaconus modestus, distributed in the Northwest Pacific, has high economic value and is used in various seafood. In this study, the morphological and genetic characteristics of T. modestus and T. septentrionalis were compared and analyzed. We observed the external and internal morphology of T. modestus, sketched skeletal elements, and analyzed phylogenetic evolutionary relationships using the cytochrome c oxidase subunit I (COI) gene on mitochondrial DNA compared to T. septentrionalis. The T. modestus observed in this study had blackish-brown patterns irregularly scattered on the gray-brown body, and the fins were blue-green. Genetic analysis results based on the COI sequences of T. modestus showed seven types of base sequence variation; however, the homology was more than 98.8%. In addition, as a result of comparison of the COI nucleotide sequences and phylogenetic analysis in Tetraodontiformes, two T. septentrionalis sequences (JN813099, MW485059) were similar to T. modestus with 99% homology, and the other two T. septentrionalis sequences (EF607583, KP267619) were similar to those of species belonging to another genus Thamnaconus with 95% homology with T. modestus. It was not easy to classify the species based on morphological characteristics, and phylogenetic analysis between T. modestus and T. septentrionalis confirmed the difference in classification. These results provide the external and internal morphology of T. modestus and will be used as important information for the taxonomic study of T. modestus and T. septentrionalis.

• Korean Journal of Ichthyology
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• v.26 no.3
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• pp.222-229
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• 2014

As a study for offshore wind farm, we investigated the fish fauna of the Wi-do, Younggwang-gun, Chollabuk-do, Korea. From the four times collection of fish species from October 2013 to June 2014, we collected 46 species of 26 families including 9 orders. Among them, the fish of family Gobiidae includes the most number of six species (13.6%). The dominant species was the Argyrosomus argentatus with 53.10%. Total of 17 fish species, including the Cynoglossus joyneri were collected from all of four collecting sites. On the other hand, 13 species including Inimicus japonicus were collected from only one site. Being the wind farm under construction, fish will temporary decrease in this area. But in the long term, we think that Oplegnathus fasciatus, Sebastes shlegelli and others will increase with good inhabited environment provided by the wind farm structures.