• Ocean and Polar Research
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• v.36 no.1
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• pp.1-12
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• 2014

This study investigates spatial and temporal variations in the generation and propagation of internal tides around the Korea Strait using a three-dimensional high resolution model (Regional Ocean Modeling System; ROMS). The model results were verified through comparison with in-situ current measurements from an array of 12 acoustic Doppler current profilers (ADCPs) deployed in the Korea Strait. Fluxes and distributions of internal tidal energy were calculated using simulation results gathered in February and August. Our analyses reveal that energetic semidiurnal internal tides are generated in a region around the Korea Strait shelf break ($35.5^{\circ}N$, $130^{\circ}{\sim}130.5^{\circ}E$), where the strong cross-slope semidiurnal barotropic tidal currents interact with a sudden topographical change. The semidiurnal internal tidal energy generated in summer displays values about twice as large as values in winter. Propagation of semidiurnal internal tides also reveals seasonal variability. In February, most of the semidiurnal internal tides propagate only into the open basin of the East Sea due to weak stratification in the Korea Strait, which inhibits their southwestward propagation. In August, they propagate southwestward to $35.2^{\circ}N$ along the western channel of the Korea Strait because of strong stratification. In addition, semidiurnal internal tides generated in a region west of Tsushima Island are found to propagate to the coast of Busan. This can be explained by the intensified stratification due to the strong intrusion of bottom cold water in the western channel of the Korea Strait during summer.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.4
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• pp.9-14
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• 2007

This study reviewed the behavior(movement) characteristics of floating marine debris flowing in the Nakdong River Estuary using a simple numerical particle-tracking model on the conditions of the maximum water discharge outflow from the Nakdong River barrage during the passage of typhoon Maemi in 2003. The simulation showed that the particle distribution and movement of floating marine debris in the Nakdong River Estuary reached a stable state at 72 hours after the typhoon had passed, during the flood period of river discharge. The quantity of floating particles distributed on the east coast of Gadeok and Jinu Islands increased by 40% at 33 hours after starting the model, while the change in other sea areas was 20-40%.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.6
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• pp.657-663
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• 2009

This paper reports the strandings of sea turtles on Korean shores monitored for the first time in 2008. A total of 19 sea turtles, consisting of 12 greens and 7 loggerheads, were recorded as stranded from the east coast to the south including Jeju Island. Reported strandings reached a peak in July and dominant area was Jeju Island. The curved carapace length of loggerhead sea turtles ranged 65-84.2cm and that of green sea turtles ranged 39.2-90cm, indicating most of them were immature to sub-adult. Out of 19 turtles, 11 were found dead with unknown reasons. Possible causes of death may include drawning by fishing gear, swallowing of marine debris, boat collision, and diseases. An immature green sea turtle tagged with a satellite transmitter spent winter near Jeju Island where it was released, suggesting that the Island provide immature greens a feeding ground. Considering thousands of sea turtles crawl on Japanese shores for nesting every year, the number of sea turtles reported in Korean waters was relatively small. Therefore, it is suggested that an appropriate monitoring system be necessary to protect and conserve endangered sea turtle species in Korean waters.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.868-877
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• 2013

To understand the effects of marine environmental and meteorological parameters on laver Porphyra yezoensis production at Nakdong River Estuary, we analyzed marine environmental (water temperature, salinity, nutrients, etc.) and meteorological properties (air temperature, wind speed, precipitation, sunshine hours) with yearly and monthly variations in laver production over 10 years (2003-2013). Air and water temperature, wind speed, sunshine hours and precipitation were major factors affecting yearly variability in laver production at the Nakdong River Estuary. Lower air and water temperatures together with higher levels of nutrients and sunshine and stronger wind speeds resulted in higher laver harvests. Salinity and nitrogen did not show clear correlations with laver production, mainly due to the plentiful supply of nitrogen from river discharge and the low frequency of environmental measurements, which resulted in low statistical confidence. However, environmental factors affecting monthly laver production were related to the life cycle (culturing stage) of Porphyra yezoensis and were somewhat different from factors affecting annual laver production. In November, a young laver needs lower water temperatures for rapid growth, while a mature laver needs much stronger winds and more sunshine, as well as lower temperatures for massive production and effective photosynthesis, mostly in December and January. However, in spring (March), more stable environments with fewer fluctuations in air temperature are needed to sustain the production of newly deployed culture-nets ($2^{nd}$ time culture). These results indicate that rapid changes in weather and marine environments caused by global climate change will negatively affect laver production and, thus, to sustain the yield of and predict future variability in laver production at the Nakdong River estuary, environmental variation around laver culturing farms needs to be monitored with high resolution in space and time.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.253-260
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• 2005

Recently, the storms which hit Korean Peninsula are getting bigger, and the damages from the storms are wide spreaded. Thus, and approach with disaster prebention to offshore area and/or opened island area is neccessary. The existing wave design parameter was calculated with linear regular wave models inputting deep water design wave or wind sources. so it wasn't able to deal with wind-induced waves, interactions with waves, and redistribution of wave energy simultaneously. In this study, we made numerical simulation with SWAN(Simulation Waves Nearshore) Model which can consider development of waves and winds and their interference. The result from this model shows much different with those from existing model's. so the result from this study, especially in this modeling area, could be used for harbor design and coastal disaster prevention field in the future.

• ALGAE
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• v.18 no.3
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• pp.217-223
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• 2003

Seasonal growth and maturation process of Caulerpa okamurae were investigated in natural populations and in culture. Monthly sampling was carried out by SCUBA diving at Baekunpo, Busan, southeastern coast of Korea from November 1999 to October 2001. Growth of erect branches depended mainly on the water temperature in the natural habitat. Maximum length of erect branches was 14.0 $\pm$ 1.4 cm in June 2001 when the water temperature was 19.7$^{\circ}C$ and minimum was 2.8$\pm$0.2 cm in April when the water temperature was 14.7$^{\circ}C$. Fresh weight of erect branches was 3.9 $\pm$ 0.5 g in June 2001 and 0.2 $\pm$ 0.04 g in September 2000. Biomass of the population was maximum of 922.5 g dw${\cdot}m^{-2}$ in July and minimum of 125.6 g dw${\cdot}m^{-2}$ in April. Gametangial network was observed on the ramuli when the water temperature was over 19$^{\circ}C$ in August 2000 and June 2001. In the culture regime of 4 temperatures (15, 20, 25 and 30$^{\circ}C$) and 3 irradiances (20, 50 and 80 $\mu$mol${\cdot}m^{-2}{\cdot}s^{-1}$) combination, the maturation of excised erect branches was mainly affected by temperature. Maturation was induced under all irradiance conditions at 20 and 25$^{\circ}C$; under 80 $\mu$mol${\cdot}m^{-2}{\cdot}s^{-1}$ at 15$^{\circ}C$; and under 20 $\mu$mol${\cdot}m^{-2}{\cdot}s^{-1}$ at 30$^{\circ}C$. The highest rate of maturation was 64% under 20 $\mu$mol${\cdot}m^{-2}{\cdot}s^{-1}$ at 25$^{\circ}C$. These results suggested that developmental initiations of C. okamurae occurred at higher than 13$^{\circ}C$ and maturation took about 270 degree-days.

• Proceedings of KOSOMES biannual meeting
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• 2007.11a
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• pp.23-28
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• 2007

This study estimated the behavior(movement) characteristics of floating marine debris flowing in the Nakdong River Estuary using a simple numerical particle-tracking model. This numerical experiment considered the maximum water discharge outflow from the Nakdong River barrage during the passage of typhoon Maemi in 2003. The simulation showed that the particle distribution and movement of floating marine debris in the Nakdong River Estuary reached a stable state at 72 hours after the typhoon had passed, during the flαxl period of river discharge. The quantity of floating particles distributed on the east coast of Gadeok and Jinu Islands increased by 40% at 33 hours after starting the model, while the change in other sea areas was $20{\sim}40%$.

• Journal of Korean Society for Geospatial Information Science
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• v.15 no.2 s.40
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• pp.77-85
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• 2007

According to the survey data during the Japanese Occupation Period, the length of South Korea's coastline is about 11,542 km, including the coastlines of land and islands. It will be very expensive and time-consuming to revise/renew accurately this coastline data through site survey, it will cost great money and time. Also, various development projects such as reclamation works on public waters, constructions of ports/harbors, etc. are frequently changing the coastal areas and coastlines, causing many renewal projects on coastal maps. For such reason, appropriate alternatives for site survey are necessary. This paper demonstrate the utilization of RTK-GPS survey data, qualitative analysis and 3D topographic analysis for extracting the change in five coastal areas (Songjeong, Haeundae, Kwanganri, Songdo and Dadaepo). The local experimental areas subjected for this research were limited to five coastal areas near Busan.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.1
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• pp.3-9
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• 2013

Development of housing, industrial and public lands has been a cause to increase a temperature of a city higher than that of a rural area. Knowing that, the research analyzed temperature changes in a riverside district and a coastal area depending on the land usage and climate change in the areas. Add to this, the study examined a correlation between topographic characteristics and temperature changes. According to the results, the temperature was increased by $1.80^{\circ}C$ in 2007 comparing to 2003 while the wind velocity was reduced by 0.24m/s. In addition, a more number of areas were designated as build-up areas which, in return, decreased the forested land. The analysis on the correlation reported that the riverside district has more of grassland and bare land while the coastal area has more of wooded land and grassland. The study is expected to be used as fundamental data for research on heat island effect which would be different by each regional characteristic as it proposes measures to solve the heat island effect.

• Ocean and Polar Research
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• v.27 no.2
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• pp.135-148
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• 2005

Macrobeilthic fauna were collected using a van Veen grab $(0.1m^2)$ to investigate the spatial characteristics of the macrobenthos community at 28 stations near the Nakdong River estuary, Southeast Korea, in September 2001. A total of 203 species were sampled with a mean density of $1,554 ind./m^2$ and a biomass of $252.3 gWWt/m^2$. Annelids were the dominant faunal group in terms of species and density, with 68 species and a mean density of $1,031ind./m^2$, which comprised 33.5% and 66.3% of the total benthic animals, respectively. Based on density, three Polychaetes were dominant Tharyx sp· $(420ind./m^2)$, Lumbrineris longifolia $(143ind./m^2)$, and Sternaspis scutata $(118ind./m^2)$, along with a bivalve Theora fragilis $(129 ind./m^2)$. On cluster analysis, the benthic community was classified into four groups based on the species composition: Group-1 occurred in disturbed areas, Group-II in coastal regions, Group-III in central mariculture grounds, and Group-IV offshore. Environmental factors (mean gain size, organic carbon, and depth) were primarily correlated with the macrobenthos community structure. A benthic pollution assessment based on the macrobenthos community structure showed that Group-I and Group-II were located in a coastal area that had been severely disturbed by construction of Busan new port and various pollutants, Group-III was gradually polluted, while offshore Group-IV was the most stable.