• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.1
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• pp.31-41
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• 2010

Harmful dinoflagellate, Cochlodinium polykrikoides, has always occurred in southern coastal waters every year during summer, but it did not occur in 2009. A comparative study on outbreak in 2007/2008 and non-outbreak of C. polykrikoides in 2009 was performed based on environmental parameters and phytoplankton appearances. Samples were obtained at 13 stations from Yeosu to Wando waters in 2007-2009. The heavy rainfall was associated with the decrease of surface water temperature below $20^{\circ}C$ in July, the decrease of salinity below 31psu in August and increase of pH to 8.4 in Augus, 2009. concentration of DIN in 2009 was approximately too times as high as those of 2007 and 2008, and the ratioes of N:P and Si:N in 2009 showed Redfield ratio to be above the value of 16. This indicates that Redfield ratioes were significantly different between 2007/2008 and 2009. Dominant species during the field survey were shown to be Chaetoceros spp., Skeletonema costatum and Thalassiosir spp. in diatoms and to be Ceratium spp. in dinoflagellate. In partiuclar, Gonyaulax polygramma occurred in August, 2009 instead of C. polykrikoides. Consequently, the massive rainfall and shortage of sunshine contributed to considerable variation in environmental parameters which were associated with delay in the timing of rapid growth phase of C. polykrikoides.

• Journal of Korea Water Resources Association
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• v.36 no.2
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• pp.285-300
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• 2003

An event-based, kinematic, infiltration-excess, and distributed rainfall-runoff model using weather radar and Geographic Information System(GIS) was developed to acknowledge and account lot the spatial variability and uncertainty of several parameters relevant to storm surface runoff and surface flow The developed model is compatible with raster GIS and spatially and temporally varied rainfall data. To calibrate the model, Monte Carlo simulation and a likelihood measure are utilized; allowing for a range of possible system responses from the calibrated model. Using rain gauge adjusted radar-rainfall estimates, the developed model was applied and evaluated to a limited number of historical events for the Ralston Creek and Goldsmith Gulch basins within the Denver Urban Drainage and Flood Control District (UDFCD) that contain mixed land use classifications. While based on a limited number of Monte Carlo simulations and considered flood events, Nash and Sutcliffe efficiency score ranges of -0.19∼0.95 / -0.75∼0.81 were obtained from the calibrated models for the Ralston Creek and Goldsmith Gulch basins, based on a comparison of observed and simulated hydrographs. For the Ralston Creek and Goldsmith Gulch basins, Nash and Sutcliffe efficiency scores of 0.88/0.10, 0.14/0.71, and 0.99/0.95 for runoff volume, peak discharge, and time to peak, respectively, were obtained from the model.

• Journal of Life Science
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• v.9 no.3
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• pp.276-281
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• 1999

This study was designed as a part of efforts to investigate the biochemical pollutant markers for diagnosis of marine pollutions by changes in oxygen radicals and their scavenger enzymes of the mussel (Mytilus coruscus) in South Sea of Korea. Protein contents in muscle of cultured mussel in South Sea were remarkably lower (4-14%, respectively) than those of wild mussel in Pohang of East Sea. Superoxide radical activities in muscle of cultured in South Sea were significantly higher 82∼138% than those of wild mussel in Pohang. Hydroxyl radical formations in muscle of cultured mussels in South Sea were significantly 9∼25% higher than those of wild mussels in Pohang. Superoxide dismutase (SOD) activities in muscle of cultured mussels in South Sea were significantly 16∼28% lower than those of wild mussels in Pohang. It is believed that significantly decrease of protein contents in muscle, remarkable increases of superoxide radical and hydroxyl radical in muscle of cultured mussels of South Sea may be used as a biochemical pollutant markers for diagnosis of marine pollutions. These results suggest that near-coastal water as well as neritic water of the south sea might be affected by pollutant.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.117-124
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• 2005

Recently the first stage of construction for Busan new port emerged over the sea surface at the north container terminal site. With this, there are lot of discussions and debates on increasing the water depth at the approaching channel and mooring basin from the existing 15m to 18m by dredging work in order to be able to serve 12,000TEU containership, and at the same time, correction to the reclamation plan of hinterland at the part of Undong Bay of the new port site. Since the attack of typhoon 'Maemi' in 2003, it is expected that the design wave parameters for coastal and harbor structures in this area would be somewhat changed and so the extreme wave condition at each terminal and tranquility of berthing area does, and therefore, it is necessary to analyze the tranquility at each berth. Hence in this study, we constructed a wave model for these conditions and performed simulation together with the circulation model simulation, compared with the field data collected. The result showed the increase of the harbor response throughout the basin but not severe condition. However, a certain location needs to be prepared for the rough sea condition when a severe typhoon hit the site.

• The Korean Journal of Quaternary Research
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• v.24 no.2
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• pp.35-48
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• 2010

The purpose of this study is to investigate paleoenvironmental conditions of the shallow sea around Jeju Island during the Late Holocene using geochemical contents of the bivalve (Glycymeris albolineata) collected from the Sangmori Shell Mound. The bivalve shell used shows the archaeological age of 2,300 yr BP. Stable carbon and oxygen isotope compositions show that growth rates decreased with aging. Coeval trends of both isotope compositions can be observed: heavier values during winters and lighter values summers except for their young and old growth stages. The seasonality of bivalve shell appear to reflect seasonal variations of paleotemperature as well as paleosalinity. Especially China Coastal Water with low salinity was transported into the southern Jeju Strait from Changjiang River during summer periods. Heavier carbon isotope values during winter indicate higher productivity, and this is supported by high density of phytoplanktons and higher chlorophyll contents during winter time. For accurate interpretation, monitoring of present-day conditions of shallow marine water as well as additional geochemical analysis of the same Recent bivalve may be necessary.

• Journal of Korea Water Resources Association
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• v.41 no.10
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• pp.983-993
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• 2008

In recent times, sea level increasing caused by abnormal weather and global warming, sea-sand dredging and complex development causes various kind of erosion damages onto the coastal area in the world. The various types of erosion control and protection methods are applied but there are no signs of fruitful effectiveness. The PC concrete protection block for shore protection structure is practically installed in globally but most of structures in the present day became villainous because of bad accessability. In this study, hydrophilic revetments for control and protection of coastline erosion will be developed in order to make up for a faculty of the shore erosion protection block with better accessibility and excellent protection ability. Experimental measurements were researched to insure for the capacity and facility on reflection coefficient, overtopping volume, and overtopping height characteristics of newly developed shore erosion protection block in model tests. As the result, hydraulic model tests show much excellent than the general step block. Field tests were carried out also to verify through vegetative test on an affinity and construction work test of control-protection on coastline erosion with actual utilization. In the latter case, deposition of sand accumulation occurred in fairly short time at the established reaches and then we can be confirmed to utilize for newly developed block as the revetments for control and protection of coastline erosion.

• Journal of Korea Water Resources Association
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• v.51 no.7
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• pp.543-554
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• 2018

A methodology has been presented for evaluating the partial safety factors on the sliding failure mode of vertical caissons of composite breakwaters and for determining the cross sections of those by Level I reliability-based design method. Especially, a mathematical model has been suggested for the sake of a consistency of code format as well as convenience of application in practical design, for which the uncertainties associated with buoyancy and its own weight can be taken into account straightforwardly. Furthermore, design criteria equation has been derived by considering accurately the effect of uplift pressure, so that the cross sections of caissons can be assessed which must be safe against the sliding failure. It has been found that cross sections estimated from partial safety factors proposed in this paper are in very good agreement with the results of Level II AFDA and Level III MCS under the same target probability of failure. However, partial safety factors of the Technical Standards and Commentaries for Port and Harbour Facilities in Japan and Coastal Engineering Manual in USA tend to estimate much bigger or smaller cross sections in comparison to the present results. Finally, many reliability re-analyses have been performed in order to conform whether the stability level of cross section estimated by Level I reliability-based design method is satisfied with the target probability of failure of partial safety factors or not.

• Journal of Korea Water Resources Association
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• v.51 no.7
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• pp.565-574
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• 2018

High population density in deltaic settings, especially in Asia, tends to increase and causes coastal flood risk because of lower elevations and significant subsidence. Large flood annually causes numerous deaths and huge economic losses. In this paper, an innovative technology of spatial satellite imagery has been used as tool to analyze the socio-economic flood-related damage in Mekong river basin. The relationship between nightlight intensity and flood damages has been determined for the period of 1992-2013 with a spatial resolution of 30 arc sec ($0.0083^{\circ}$), which is nearly one kilometer at the equator. Flow path distance was calculated to identify the distance of each cell to river network and to examine how nightlight intensity correlate to the area close to and far from river network. Statistical analysis results highlight the significant correlation between nocturnal luminosity intensity and flood-related damages in countries along the Mekong river (i.e., Cambodia, China, Lao PDR, Thailand, and Vietnam). This result reveals that the areas close to the river network correspond to high human distribution and causes huge damage during flooding. The result may provide key information to the region with respect to decisions, attentions, and mitigation strategies.

• Animal Systematics, Evolution and Diversity
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• v.14 no.3
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• pp.173-192
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• 1998

This study was made as a part of the benethic fauna of Geojedo Island. The material was obtained from 17 localities (Fig. 1) along the coastal sea of Geojedo Island and it's adjacent waters during the years 1995-1998. This paper includes 38 species from a limited area of the southern part of Korea and includes 13 previously known species by Rho(1975-1991). Of these Didemnum (D.) pardum, Symplegma oceania, and Styela coriacea, are new to the Korean fauna, and 22 species are newly added to the fauna of Geojedo Island. We provided taxonomic notes and brief notes on the ascidian fauna, and the biogeographical distribution of Geojedo island. Its ascidian fauna are characterized by a high percentage of 18(47.4%) warm-water species and the extreme scarcity of eight(21.1%) boreal-water forms. This result may be attributable to the fact that Geojedo island and its adajacent waters are located under the influence of the warm Kuroshio Current.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.3
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• pp.164-170
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• 2005

To investigate the aquatic environmental factors and processes controlling primary production in the Seomjin River estuary, chlorophyll a, nutrients, pH, SS, DO, temperature, salinity and primary productivity were measured in February, April, August and October, 2001. Primary productivity values ranged between 50.7 and 14,120.3 mg C $m^{-3} day^{-1}$ during the sampling period. In contrast to other estuaries, light condition did not seem to be the important limiting factor far primary production due to high water-column transparency during most of the time. The autumn bloom occurred in regions where salinity values ranged between 10 and 20 psu. This phenomenon appeared to develop every year and deserves further investigation. The behavior of nutrients, which is one of the major factors controlling the primary productivity, appeared to be governed by salinity regimes. The main source of nitrogenous nutrients seemed to be the freshwater runoff from the Seomjin River. However, that of phosphorus seemed to be from the industrial wastewater in Gwangyang area. The primary pro-duction of phytoplankton in the study area varied with space and time, showing a close correlation with water column transparency, and exhibited higher values compared to those of adjacent coastal regions in Gwangyang Bay.