• Journal of the Korean Society of Environmental Restoration Technology
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• v.26 no.6
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• pp.165-177
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• 2023

Field surveys were conducted at a total of 50 locations targeting naturalized plants on Ulleung-do. A total of 109 taxa were identified, including the list of naturalized plants in the preceding literature. The naturalized plants of Ulleung-do had a high proportion of Asteraceae, which appeared frequently in the habitat of the ruderal type. There were no naturalized plants that settled only on Ulleung-do, and all naturalized plants found on Ulleung-do first settled on the Korean Peninsula. This was proved by the high rates of epecophyten (90.8%) and the introduction period 2nd (70.6%). On the other hand, among ecosystem-disturbing species that have a great influence in the inland of the Korean Peninsula, Hypochaeris radicata and Rumex acetosella appeared in a limited area in Ulleung-do. On the other hand, Lapsana communis appeared in high density along the forest edge, requiring management of naturalized plants different from those in the Korean Peninsula. Naturalized plants on Ulleung-do showed a rapid increase in the 1990s after increased academic research, coastal road development, and other development projects. This highlights the necessity for continuous research on the pattern of naturalized plant occurrence after the completion of the Ulleung Airport, which is currently under construction.

• Korean Journal of Environmental Biology
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• v.39 no.4
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• pp.559-572
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• 2021

A survey was conducted to analyze water masses and spatial distributions of phytoplankton communities at 15 stations on the surface and chlorophyll a maximum layers (CML) in the western South Sea of Korea from September 8 to 9, 2021. As a result, water masses were classified into Coastal Waters (CW) with relatively low salinity, the Tsushima Warm Current (TWC) with high water temperature and high salinity, and mixed waters (MW) showing a mixture of these two water masses. Turbidity showed high concentration in both the surface and CML. The chlorophyll a concentration was as low as 0.90±0.43 ㎍ L^-1 in the surface, more than 1.1 ㎍ L^-1 in CW, around 1.0 ㎍ L^-1 in MW, and less than 0.5 ㎍ L^-1 in the TWC. CML was 1.64±0.54 ㎍ L^-1. Regarding species composition of phytoplankton communities, there were 57 species in 31 genera(diatoms, 57.8%; dinoflagellates, 35.1%; and other phytoflagellates, 7.1%). The phytoplankton standing crop had 4.6±7.6 cells mL^-1 in the surface, more than 30 cells mL^-1 in the CW, 2-5 cells mL^-1 in the MW, and less than 2 cells mL^-1 in the TWC. CML was slightly higher than the surface with a variation of 5.7±8.4 cells mL^-1. Dominant species were found to be Rhizosolenia flagilissima f. flagilissima, Skeletonema costatum-ls, and Nitzschia sp./ small size in the surface. For the CML Rh. flagilisima f. flagilissima showed a dominance of 12.0%. For the surface, the diversity variation was 2.36±0.40, which was high for TWC but low for MW. For CML, the diversity variation was 2.29±0.52, which was slightly lower than that of the surface. The dominance in the surface was 0.50±0.15, with a fluctuation range of more than 0.5 in MW and less than 0.5 in the TWC, which was different from the diversity. According to correlation analysis and principal component analysis (PCA), the presence of phytoplankton standing crops was high in CW but low in MW and TWC. That is, phytoplankton communities in early autumn were strongly affected by the expansion and mixing of water masses in western South Sea.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.2
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• pp.64-73
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• 2015

The distributions of Pb and Cd concentrations in the surface seawater of the East Sea were investigated during the R/V Lavrentyev cruise (July 2009) in which four transects from Russia shore to South were conducted to collect 26 surface water samples. The total dissolved concentrations of Pb and Cd were measured using ICP-MS (Perkin Elmer, DRC-e). In the coastal area, their concentrations of Russia shore (Pb, 0.08; Cd, 0.10 nM) were comparable for Cd but on the other hand, 6 times lower for Pb than Korea shore (Pb, 0.49; Cd, 0.11 nM). In the subregion, their concentrations of Warm region (Pb, 0.22; Cd, 0.01 nM) were about 1.7 times higher for Pb but 0.4 lower for Cd than Cold region (Pb, 0.13; Cd, 0.14 nM). The distributions of Pb and Cd concentrations were divided by lowest level at $10^{\circ}C$ of water temperature. Below $10^{\circ}C$, Pb and Cd concentrations increased when surface water temperatures decreased. Above $10^{\circ}C$, their concentrations increased with temperature, which showed highest concentrations in the Ulleung basin, directly influenced by flux from East Korean Warm Current and neighboring countrys (Korea and Japan). Specially, in the case of Pb, the concentrations decrease remarkablely with temperatures decrease from D10 directly influenced by flux from East Korean Warm Current, which shows highest Pb level. By comparing with other sea areas (Western Mediterranean, East Pacific), Pb concentrations in the East Sea were a little higher. The influence of East Korean Warm Current and neighboring countrys (Korea and Japan) may be relatively important. Therefore, the distribution of Cd may primarily be influenced by mixing of different water masses while the distribution of Pb may mainly be influenced by flux from East Korean Warm Current and atmospheric inputs. River inputs and interaction with particulate materials may also some roles for the distribution of these elements.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.2
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• pp.61-67
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• 1975

Oceanographic conditions of the coastal water around Chungmu, one of the most important oyster farming areas in Korea, were studied from May to November in 1974 to find out the environmental influence to oyster farming. Six localities, Goseong Bay, Jaran Bay, off Saryangdo, Hansilpo, Tong-yeong Bay and Juklimpo were selected for monthly oceanographic observation and biological sampling. Flood current running westward brings saline water from the south-east and ebb current brings the low salinity water of Jinju Bay into this area. The waters in Juklimpo, Hansilpo and Tong-yeong Bay are slightly cooler and more saline than the waters in Goseong Bay, Jaran Bay and off Saryangdo. The amount of dissolved oxygen is lowest in September and Hansilpo has the least oxygen during summer. Silicate content is lower in waters of Tong-yeong Bay, Juklimpo and off Saryangdo than those of Goseong Bay, Hansilpo and Jaran Bay. Suspended matter in this area ranges from 7.4 to 16.6 mg/l and scarce in Jaran Bay, Juklimpo and off Saryangdo. Chlorophyll a shows large seasonal variation and local fluctuation. Composition of phyto-plankton reveals the difference between the waters of Goseong Bay, Jaran Bay and off Saryangdo and the waters of Hansilpo, Tong-yeong Bay and Juklimpo. The growth of oyster was good in Juklimpo, Tong-yeong Bay and Goseong Bay and worst in Hansilpo. The highest mortality was observed $82\%$ in the waters off Saryangdo.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.34 no.2
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• pp.117-134
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• 1998

The study on the Assembling Mechanism of the Hairtail, Trichiurus lenpturus, at the Fishing Grounds of the Cheju Strait had been investigated by analyzing the relationship of the oceanographic conditions and the fishing ground of the Hairtail in the Cheju Strait. 1. The fishing grounds of the hairtail at the Cheju Strait are formed at the bottom of a high temperature of the tidal front at the coast. area of northern Cheju Island, the tip of the linguiform is high in salinity at the eastern and western entrances of Cheju Island, low salinity eddy on the surface and its surrounding front, various water masses in the Strait and coastal waters of the South Sea in Korea. 2. The fishing grounds of the Hairtail at the Cheju Strait begins with the sea surface temperature higher than $15^{\circ}C$ and the incoming of low salinity water now from the East China Sea. 3. Estimation of optimum temperature and salinity per season based upon analysis for relationship between temperature of water and salinity of the bottom layer and the catch is : 15.2~$16.4^{\circ}C$, 34.20~34.40${\textperthousand}$ in spring(June); 14.4~ $17.0^{\circ}C$, 33.70~34.30${\textperthousand}$ in summer(July~September); and 15.7~ $18.6^{\circ}C$, 33.70~34.50$\textperthousand$ in autumn(October~December). Hairtail are mostly caught at the Yellow Sea Warm Current and Tsushima Current with temperature over $14.5^{\circ}C$ and salinity over 33.70${\textperthousand}$ at the bottom layers of the Cheju Strait. 4. Considering the relationship between the amount of hairtail catch and the water temperature of bottom layer, when the bottom water being above $14.0^{\circ}C$ flowed into Cheju Strait through the western entrance of the strait in summer, the ca-h appears to have been abundant. In contrast, the catch has been poor when the temperature of such water was recorded to be below $13^{\circ}C$ Therefore, distribution patterns of water at the bottom layer can be used as a forecast index whether the catch of a certain year will be good or poor.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.2
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• pp.242-251
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• 2013

Recently, while global concern over offshore resources exploration and development is being increased rapidly, offshore plant industry is highlighted as an industry of high added value. Along with this global trend, domestic concern over offshore plant development is being increased as well. In the overseas case, a marine geotechnical survey guideline for confirming characteristics of seabed sediments is available at the time of installation of offshore plant but such guideline is not available in our country. In this study, survey techniques fit for domestic marine environment was applied according to overseas guideline at southern coastal area, Korea. Among the marine geophysical survey techniques being proposed abroad, magnetic survey and seabed photograph were excluded. However, highly reliable data analysis was enabled for marine geophysical survey, which includes in-situ coring investigation and laboratory soil test. In addition, continuous ocean current survey was included to find scour potential due to the current around the offshore plant. Although coring depth is not so deep, we predicted geological structure through the analysis of amplitude features of seismic data. Characteristics of seabed sediments cold be obtained regionally and directly through combined analysis of marine geophysical survey data and coring data.

• Journal of Wetlands Research
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• v.15 no.3
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• pp.423-430
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• 2013

An algorithm to allow shoreline movement during numerical experiment on sediment transport, deposition or resuspension for general coastal morphology is proposed here. The bed slope near shoreline, i.e. mean sea level, is influenced by bed material, tidal current, waves, and wave-induced current, but has been reported to remain within a stable range. Its annual variation is not large, either. The algorithm is adjusting the bathymetry, if the largest bed slope within shoreline band exceeds a given bed slope due to continuous erosion at zones below the shoreline. This algorithm automatically describes retreat of shoreline caused by erosion, when used within a numerical system. The algorithm was tested to a situation which includes a continuous dredging at a point, and showed satisfactory development of concentric circle contours. Next, the algorithm was tested to another situation which includes sinking of eroded part of bed plate, and produced satisfactory results, too. Finally, the algorithm was tested to a movable-bed laboratory experimental conditions. The shoreline movement behind detached breakwater was reasonably reproduced with this algorithm.

• Korean Journal of Remote Sensing
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• v.36 no.2_2
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• pp.249-261
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• 2020

Coastal monitoring using multiple platforms/sensors is a very important tools for accurately understanding the changes in offshore marine environment and disaster with high temporal and spatial resolutions. However, integrated observation studies using multiple platforms and sensors are insufficient, and none of them have been evaluated for efficiency and limitation of convergence. In this study, we aimed to suggest an integrated observation method with multi-remote sensing platform and sensors, and to diagnose the utility and limitation. Integrated in situ surveys were conducted using Rhodamine WT fluorescent dye to simulate various marine disasters. In September 2019, the distribution and movement of RWT dye patches were detected using satellite (Kompsat-2/3/3A, Landsat-8 OLI, Sentinel-3 OLCI and GOCI), unmanned aircraft (Mavic 2 pro and Inspire 2), and manned aircraft platforms after injecting fluorescent dye into the waters of the South Sea-Yeosu Sea. The initial patch size of the RWT dye was 2,600 ㎡ and spread to 62,000 ㎡ about 138 minutes later. The RWT patches gradually moved southwestward from the point where they were first released,similar to the pattern of tidal current flowing southwest as the tides gradually decreased. Unmanned Aerial Vehicles (UAVs) image showed highest resolution in terms of spatial and time resolution, but the coverage area was the narrowest. In the case of satellite images, the coverage area was wide, but there were some limitations compared to other platforms in terms of operability due to the long cycle of revisiting. For Sentinel-3 OLCI and GOCI, the spectral resolution and signal-to-noise ratio (SNR) were the highest, but small fluorescent dye detection was limited in terms of spatial resolution. In the case of hyperspectral sensor mounted on manned aircraft, the spectral resolution was the highest, but this was also somewhat limited in terms of operability. From this simulation approach, multi-platform integrated observation was able to confirm that time,space and spectral resolution could be significantly improved. In the future, if this study results are linked to coastal numerical models, it will be possible to predict the transport and diffusion of contaminants, and it is expected that it can contribute to improving model accuracy by using them as input and verification data of the numerical models.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.1
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• pp.1-12
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• 2013

Acoustic backscatter profiles were measured by Eco-sounder along an east-west section in the mid-eastern Yellow Sea and at an anchoring station in the low salinity region off the Keum River estuary in September 2012, with observing physical water property structure by CTD. Tidal front was established around the sand ridge developed in 50 m depth region. Internal waves measured by Eco-sounder during low tide period in the eastern side of the sand ridge were nonlinear depression waves with wave height of 15 m and mean wavelength of 500 m. These waves were interpreted into tidal internal waves that were produced by tidal current flowing over the sand ridge to the southeast. When weakly non-linear soliton model was applied, propagation speed and period of these internal depression wave were 50 m/s and 16~18 min. Red tides by Dinoflagelates Cochlodinium were observed in the sea surface where strong acoustic scattering layer was raised up to 7 m. Hourly CTD profiles taken at the anchoring station off the Keum River estuary showed the halocline depth change by tidal current and land-sea breeze. When tidal current flowed strongly to the northeast during flood period and land-breeze of 7 m/s blew to the west, the halocline was temporally raised up as much as 2 m and acoustic profile images showed a complex structure in the surface layer within 5-m depth: in tens of seconds the declined acoustic structure of strong and weak scattering signals alternatively appeared with entrainment and intrusion shape. These acoustic profile structures in the surface mixed layer were observed for the first time in the coastal sea of the mid-eastern Yellow Sea. The acoustic profile images and turbidity data suggest that relatively transparent low-layer water be intruded or entrained into the turbid upper-layer water by vertical shear between flood current and land breeze-induced surface current.

• Journal of Korea Port Economic Association
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• v.36 no.4
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• pp.53-74
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• 2020

It is important to understand the current status and problems of the North Korean shipping industry to prepare for inter-Korean trade in the future era of peace in the Korean Peninsula. In this study, the status of vessels calling in North and South ports was analyzed by year, cargo type (vessel type), and North Korean port type using Port-MIS data. In particular, considering the three years (2006-2008) in which inter-Korean trade was the most active, the flow of maritime transport was analyzed by visualizing data on vessels' arrival and departure in the North and South ports. Findings revealed that sea transportation between Haeju-Incheon was the most frequent, while the Haeju-Mokpo and Nampo-Incheon routes in the west coast area, and the Najin-Busan route in the east coast area were active. With reference to general cargo vessels, ports located on the west coast of Korea tended to operate between those located on the North coast of North Korea and on the east coast of South Korea. These results are expected to serve as a basis for establishing research and policies related to coastal shipping between the two Koreas in the future.