• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.2
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• pp.160-167
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• 2014

The feeding habits of Tridentiger bifasciatus were studied using 733 individuals collected in the tidal creek at Sangnae-ri, Suncheon, Korea, using a push net, monthly, from April 2011 to March 2012. The standard length (SL) of the specimens ranged from 1.5 to 8.2 cm. The stomach content analysis indicated that T. bifasciatus consumed mainly amphipods, such as Corophium sp., while copepods, polychaetes, and shrimps were other important prey species. In addition T. bifasciatus ate small quantities of crab larvae, fish, gastropod larvae, and insects. T. bifasciatus is a generalist that feeds on various zoobenthos, including fish. T. bifasciatus underwent an ontogenetic dietary shift. Smaller individuals (1-2 cm SL) fed mainly on amphipods. The proportion of amphipods decreased as body size increased, whereas the consumption of polychaetes increased gradually. The seasonal variation in the diet composition of T. bifasciatus was significant. Insects were common prey during summer, while the amounts of other prey, including polychaetes, were similar during spring, autumn, and winter.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.spc1
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• pp.180-188
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• 2006

We examined the effect of salt marsh vegetation on the benthic environment in macro-tidal flats at Donggeomdo, Ganghwa, on the west coast of Korea. Nine stations were established along a transect across the tidal flats, including salt marsh, and field sampling was conducted monthly from July 1997 to June 1998. During the study period, environmental parameters fluctuated as follows: salinity, 15.0 to 28.2 psu, exposure time, 613 to 702 hr/m, inundation time, 28 to 117 hr/m, sediment organic carbon, 0.71 to 1.34%, nitrogen, 0.07 to 0.16%, sulfur from 0.07 to 0.22%, mean grain size from 6.3 to $6.9{\phi}$, water content from 19.4 to 44.4%, water temperature from 4.4 to $20.4^{\circ}C$ and temperature of the surface sediments, 2.7 to $31.1^{\circ}C$, in total, seven halophyte species were sampled and found to be vertically distributed across the tidal levels. Carer scabrifolia, Suaeda maritima, Limonium tetragonum and Phragmites communis dominated the upper zone of the salt marsh, Juncus haenkei, Triglochin maritimum and P. communis dominated the middle zone, and Suaeda japonica predominated in the lower area. Principal component analysis (PCA) and non-metric multi-dimensional scaling revealed that the zonation of halophytes was related to environmental variables such as salinity and exposure time. The halophyte communities were likely related to the organic content of the surface sediment.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.271-275
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• 2005

The horizontal heat-pulse flowmeter was used to measure grounwater flow in volcanic rocks at sites in eastern part of Jeju Island, Korea. Three boreholes, Handong-1, Jongdal-1, and Susan-1, which are located at close distance from the coastline, were selected from the sea water intrusion monitoring wells. To evaluate the direction and velocity of the groundwater flow, 6 to 8 measuring points for each borehole were chosen. There are two major flow directions at Handong-1, which are toward north-east and south-east directions and velocity ranges from $2.2{\sim}3.0cm/hr\;and\;0.6{\sim}1.0cm/hr$, respectively. For Jongdal-1, two major flow directions were detected that are east and north-west and velocity ranges from $1.2{\sim}2.0cm/hr$. For Susan-1, major flow is toward east direction and the ,velocity ranges from $2.2{\sim}2.7cm/hr$ at depth $60{\sim}70m$,\;and\;0.8{\sim}0.9cm/hr$ at depth $70{\sim}80m$. In order to evaluate the tidal effect on groundwater flow, direction and velocity were measured at specific depth with time, At depth 57m of Susan-1, the velocity increased during the tidal variation, The flow direction and velocity varies with different depths, and they are also affected by tidal fluctuation. Thereafter, care must be taken when flow direction and velociy is estimated indirectly by using hydraulic head at monitoring wells.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.1
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• pp.18-24
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• 1999

The satellite image acquired by RADARSAT SAR on August 15, 1996 reveals internal waves in north coastal waters of Cheju Island. It is indicated from the image data, the tidal elevation data, and the bottom topography data, the internal waves seem to be generated by interaction between shallow bottom and tidal currents travelling in the stratified water in the summer time during the tidal changeovers from ebb to flood. The internal waves generated in such condition show patterns of trains of solitons. Probable amplitude of observed solitons is calculated using estimation of the soliton wave length from SAR image data and K-dV equation. Detection of the internal waves is very significant not only to military strategist for underwater maneuvers such as operation of submarines, but also to physical and biological oceanographers. Temporal and spatial variation of the internal waves are needed to be measured by simultaneous in-situ field study together with SAR to examine the nature of these internal waves.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.155-161
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• 1999

The land reclamation area of Saemangeum(Kunsan) is located between 126$^{\circ}$10' E~126$^{\circ}$50' E and 35$^{\circ}$35' N~356$^{\circ}$05'N at the western coast of the Korean peninsula. The are many small islands including extensive areas of semi-diurnally flooded and dewatered tidal flats. The reclamation area of Saemangeum has a range of 5.6m spring tide and the maximum tidal current speed is about 1.41m s-1 in ordinary spring tide. Most of the sediments deposited on the tidal flats are transported from the Geum river, the Manjyung river and The Dongjin river. The soil in this area consists of silty sand with the depth of 10m to 30m . The wind in winter is strong from the direction of northwest. In the past twenty years, land reclamation projects for agricutural purpose or industrial cocmplex have been mostly implemented along the western coast of Korea. Saemangeum coastal area is being constructed the33km sea dike and 40, 100ha reclamation area. The purpose of this study is to find the residual circulations in four seasons after the dike construction by a robust diagnostic and prognostic numerical model. Heat flux at the sea surface in January ,May , August , October was asopted on the basis on the daily inflow of solar radiation at the earth surface, assuming an average atomospheric transmission and no clouds , as a function of latitude and time of year(George L.P.J.E William, 1990). The discharge from the Geum , the Mankyung and the Dongjin rivers was adopted on the basis of experience formula of river flow in January , May ,August, October (The M. of C.Korea, 1993) . Water temperature and salinity along the open boundaries are obtained from the results of field observation s.

• Journal of Environmental Science International
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• v.7 no.2
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• pp.223-232
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• 1998

The spatial characteristics of stratification In Deukryang Bay were studded using observed data and analytical models. From the description of the density structure and its the potential energy anomaly (PEA) from observed data along longitudinal direction (from the mouth to head of the bays, we found that the stratification Intensity could be changed strongly by density current effect during the spring-neap tidal cycle, and depth variation. To find out density current effect for the formation of the stratification In detail, we Implemented a diagnostic approach by using the modified analytical model including density current, tidal current, surface heating and wind stirring. The model allowed for the observed similarities for the whole domain in the bay and increased tidal mixing efficiency value s up to 0.006-0.007 as compared to the results without density current effect. We found that the density current effect was also an important key factor In determining the formation of the spatial distribution of stratification.

• 한국해양학회지
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• v.30 no.2
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• pp.125-137
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• 1995

CTD, light transmission and tidal current data obtained off the Keum estuary in August, 1991 and 1992 were analyzed to look into the plume movement and the vertical structure of the plume changing with tidal currents. When the river plume was developed by a localized torrential downpour, the initial plume showed a surface lens of low salinity in the section south of the Yeon-Do. The axis of surface lens moved with tidal currents which flows mainly northeastward and southwestward tn the study area and the excursion of the lens axis reached 7 km. The plume during the ebb period showed a symmetric lens structure of low salinity which extends vertically to 3 m below the surface. During the flood period the plume deepened to 6 m below the surface in its northen side forming a sharp salinity front, which results in an asymmetric lens. We suggest that the salinity front with deepened plume moved to the north repeatedly, resulting in temperature increase and salinity decrease in the northern region off the estuary. When the river discharged continuously the large volume over 20 days, the plume forming surface lens extended to the Sybidongpa-Do and deflected to the north.

• Ocean Science Journal
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• v.40 no.4
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• pp.191-200
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• 2005

In this study an analytical tide model of uniform width with three sub-regions is presented. The three-subregions model takes into account step-like variations in depths in the direction of the channel as a way to examine the $M_2$ tide of the East China Sea (ECS) as well as the Yellow Sea (YS). A modified Proudman radiation condition has been applied at the northern open head, while the sea surface elevation is specified at the southern open boundary. It is seen that, due to the presence of an abrupt change in depth, co-amplitude lines of the $M_2$ tide are splitted to the east and west near the end of the ECS shelf region. Variations in depths, bottom friction and the open head boundary conditions all contribute to the determination of formation of amphidromes as well as overall patterns of $M_2$ tidal distribution. It is seen that increasing water depth and bottom friction in the ECS shelf results in the westward shift of the southern amphidrome. There is however no hint at all of the well-known degenerated tidal pattern being formed. It is inferred that a lateral variation of water depth has to be somehow incorporated to represent the tidal patterns in ECS in a realistic manner. Regarding the radiation factor introduced by Fang et al. (1991), use of a value larger than one, possibly with a phase shift, appears to be a proper way of incorporating the reflected waves from the northern Yellow Sea (NYS).

• Ocean and Polar Research
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• v.22 no.2
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• pp.69-80
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• 2000

A 3-D particle tracking model with normalized characteristic equations has been developed to predict the variation of near-field mixing characteristics and the far-field transport of the effluent plumes discharged from sea outfalls. The model was applied to the case study on the Masan sea outfall plumes discharged through a submerged multiport-diffuser. Numerical simulations of the effluent transport for 15 days which cover neap and spring tidal cycles in Masan Bay were conducted using fall velocities of the solid wastes and the initial plume characteristics obtained from normalized near-field characteristic equations. The results showed that time variations in near-field minimum dilutions with tidal ambient flow conditions are about $45{\sim}49$. Most of the heavy particles in the effluent plumes were settled and deposited in the vicinity of the outfalls immediately, and the finer particles were transported eastwards 3 km away from the outfalls for 15 days. A similar depositional trend of contaminated sediment was also found during a recent field survey.

• Ocean and Polar Research
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• v.30 no.1
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• pp.1-10
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• 2008

In order to find the effect of intertidal sediments on nutrient cycle in coastal environment, we measured ammonia, nitrate, phosphate, and silicate concentrations every hour during at least 12 hours in the entrance of Keunso Bay during four seasons. The content of ammonia and silicate do not change considerably with season, but nitrate shows large seasonal variation. In summer, nitrate concentration was much lower than in other seasons, which resulted from large biological uptake and active denitrification in intertidal sediments during summer. Phosphate also exhibit seasonal variations, but not that large like nitrate. N/P and N/Si ratios were lower in summer than in other seasons, which was due to active denitrification in the intertidal sediments during summer. For all seasons, ammonia concentrations were higher at low tide than at high tide, but nitrate concentrations were higher at high tide. Dissolved inorganic nitrogen concentrations measured in spring, summer, and winter were higher at high tide than at low tide, but in fall, they were higher at low tide than at high tide. For spring and winter, phosphate and silicate concentrations were higher at low tide than at high tide, while in summer and fall, they were higher at high tide than at low tide. In Keunso Bay, intertidal sediments affect significantly the nutrient cycle around the coastal areas. The intertidal sediments act as a source for ammonia and silicate, but as a sink for nitrate. However, phosphate is not considerably influenced by intertidal sediments.