• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.6
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• pp.836-843
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• 2022

In the present study, exposure to heavy metals by consumption of edible seaweeds (green laver, laver, hijiki, sea tangle, and sea mustard) was assessed based on their concentrations of lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg). The mean of heavy metal concentrations were 0.006-0.023 mg/kg for Pb, 0.037-0.156 mg/kg for Cd, 1.117-15.928 mg/kg for As, and 0.008-0.021 mg/kg for Hg. In multivariate analysis, the correlations were high between Pb levels in sea mustard, Cb levels in laver, and As and Hg level in Hijiki. However, the estimated daily intake and target hazard quotient (THQ) of the heavy metals in edible seaweeds were below their approved limits suggesting no health risks associated with seaweed consumption by Koreans.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.5
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• pp.615-625
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• 2023

This study evaluated the bacteriological safety of seawater and abalone produced in Uisin-myeon, Jindo-gun from September 2020 to December 2022 and calculated the effect of inland pollution sources on seawater and abalone. We surveyed 33 stations for seawater, 4 stations for abalone, and 7 stations for discharge water of major inland pollutants. We analyzed the coliform group, fecal coliform and Escherichia coli (E. coli) as bacteria indicators. In 924 seawater samples, the geometric mean of the coliform group and fecal coliform were <1.8-5.6 MPN/100 mL and <1.8-2.7 MPN/100 mL, respectively. The estimated 90^th percentile range for the coliform group and fecal coliform were <1.8-42 MPN/100 mL and <1.8-8.4 MPN/100 mL, respectively. The fecal coliform and E. coli levels for 107 abalone were <18-460 MPN/100 g and <18-78 MPN/100 g respectively. Moreover, the analyzed standard plate count was <30-7,700 CFU/g. The fecal coliform level and diffusion area in 7 inland pollutants were <1.8-3,300,000 MPN/100 mL and 2-2,500 m, respectively. The bacteriological safety of seawater and abalone in Uisin-myeon, Jindo-gun, was demonstrated to be a designated area according to Korean standards, a conditionally approved area per US standards, and Class A according to EU standards.

• Journal of the Korean earth science society
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• v.29 no.3
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• pp.263-279
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• 2008

This study is concerned with the optimization of models using MM5 and WRF mesoscale numerical models to simulate strong sea surface winds, such as that of typhoon Shanshan on 17 September 2006, and the Siberian high event on 16 December 2006, which were selected for displaying the two highest mean wind speeds. The model optimizations for the lowest level altitude, physical parameters and horizontal resolution were all examined. The sea surface wind values obtained using a logarithmic function which takes into account low-level stability and surface roughness were more accurate than those obtained by adjusting the lowest-level of the model to 10 m linearly. To find the optimal parameters for simulating strong sea surface winds various physical parameters were combined and applied to the model. Model grid resolutions of 3-km produced better results than those of 9-km in terms of displaying accurately regions of strong wind, low pressure intensities and low pressure mesoscale structures.

• Korean Journal of Ichthyology
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• v.13 no.1
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• pp.32-39
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• 2001

Surf-zone fishes in Daechon Beach, situated at the mouth of Cheonsu Bay, Korea, were collected by a beach seine during the spring and neap tides in August 1999. Short-term variation in species composition was analyzed based on tidal range, tidal level, and time of day. Of 24 species identified, juvenile pelagic fishes predominated in the number of individuals captured. Wilcoxon signed-rank test revealed that the number of individuals was significantly higher during the spring tide than during the neap tide. During the spring tide the fishes were more abundant at the low level than at the high level, while during the neap tide there was no significant difference. The mean density of pelagic fishes did not show significant differences between high and low tides. Demersal fishes were caught mainly in the water below the low level of the neap tide.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.313-317
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• 2005

This study aimed to estimate applicability of a model to simulate circulation in estuarine lake caused by operation of drainage gates. The model consists of 2D (depth-averaged) hydrodynamic models, Delft3D-FLOW model and operation model for drainage gates. The flow through drainage gates was calculated using weir formulae with discharge coefficient, 0.8. The simulations are performed under two conditions: uncontrolled condition and controlled by periods of two days. The results on simulation of the model showed that the water level in estuarine lake was tend to increase above mean sea level. Therefore it was proved that the calibration and verification were needed in order to applicate this model for Saemankeum area.

• Journal of the korean society of oceanography
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• v.37 no.3
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• pp.91-107
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• 2002

The wintertime upwind flow in the Yellow Sea has been investigated through a series of two-dimensional numerical experiments in an idealized basin. A total of 10 experiments have been carried out to examine the effects of wind forcing, bottom friction and the presence of oceanic currents sweeping the shelf of the East China Sea. A spatially uniform steady and periodic wind stresses are considered along with comparison of linear and quadratic formulations. The wind-driven flow in the absence of oceanic current has been computed using Proudman open boundary condition (POBC), while the wind-driven current in the presence of oceanic current has been computed using Flather’s radiation condition (FOBC). The oceanic currents to be prescribed at the open boundary have been simulated by specifying uniform sea level gradients across the Taiwan Strait and the eastern ECS shelf, Calculations show that, as seen in Lee et al. (2000), oceanic flow little penetrates into the Yellow Sea in the absence of wind forcing unless a unrealistically low rate of bottom frictional dissipation is assumed. Both steady and time-periodic wind stresses invoke the upwind flow along the central trough of the Yellow Sea, independently of the presence of the oceanic current. The presence of oceanic currents very marginally alters the north-south gradient of the sea surface elevation in the Yellow Sea. Changes in the intensity and direction of the wind-induced mean upwind flow are hardly noticeable in the Yellow Sea but are found to be significant near Cheju Island where the gradient is reduced and therewith contribution of Ekman transport increases. In case of steady wind forcing circulation patterns such as two gyres on the slope sides, a cyclonic gyre on the western slope and an anticyclonic gyre on the eastern slope persist and the upwind flow composes part of the cyclonic gyre in the Yellow Sea. While in case of the time-periodic wind stress the appearance and disappearance of the patterns are repeated according to the time variation of the wind stress and the upwind flow accordingly varies with phase delay, mostly intensifying near the time when the wind forcing is approximately near the middle of the decaying stage.

• Journal of Ecology and Environment
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• v.48 no.1
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• pp.49-59
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• 2024

Background: The present study aims to identify the pattern and size of Juniperus species (Juniperus phoenicea and J. procera) in the natural forests in terms of tree dimension, size structure and density, discussing the existing both species in Sarrawat Mountains for suggesting the preservation, conservation, and sustainable development. For achieving this, the height and mean crown diameter of each individual was measured based on 2-4 diameter measurements per ind. (506 ind. for J. phoenicea and 322 ind. for J. procera). Results: The size index of both species was classified into 7 classes: the first (< 100 cm) and the second (100-200 cm) classes were chosen to represent the juvenile stage. The total mean of the J. phoenicea population increased with the increase of altitude, while the whole population decreased after altitude of 2,000 m. The total mean of the J. procera population increased with the increase of altitude till altitude of 2,000-2,100 m. Conclusions: The present study indicated that both of species grow at low altitudes, they only grow at altitude above 1,700 m above sea level. The present study indicated that the study area has the two Juniperus spp. (J. phoenicea and J. procera) associated together all over the area. The results were discussed and compared with other related studies.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.2
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• pp.131-146
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• 2014

High-resolution seismic profiles coupled with sediment sampling were analyzed to investigate the acoustic characters and distribution patterns of the late Holocene sediments in Gamak Bay of the South Sea, Korea. The mean grain size of surficial sediment lies around $6.3{\sim}9.7{\Phi}$. Sediments in the bay consist of silt and clay with progressive decrease toward the inner bay. The seismic sedimentary sequence overlying the acoustic basement can be divided into two sedimentary units (GB I and II) by a prominent mid-reflector (Maximum Flooding Surface; MFS). The acoustic basement occurs at the depth between 20 m and 40 m below the sea-level and deepens gradually southward. The GB I, mostly occupying the channel-fill, is characterized by reflection-free seismic facies. It can be formed as late Transgressive System Tract (TST), interpreted tidal environment deposits. MFS appears at the depth of about 15~28 m below the sea-level and is well defined by even and continuous reflectors on the seismic profile. The GB II overlying MFS is composed of acoustically transparent to semitransparent and parallel internal reflectors. GB II is interpreted as the Highstand System Tract (HST) probably deposited during the last 6,000 yrs when the sea level was close to the present level. Especially, it is though that the GB II was subdivided into two layers (GB II-a and II-b) by a HST-reflector and this was classified by wind, sea water flux, and tidal current.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.579-584
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• 2009

Arrangement of the facilities for improving harbor functions depends on sea and land conditions such as the ship's arrival and departure conditions, waves and tide. And the plan and the size of the facilities depend much on harbor and marine environment condition such as cargo quantity, ship size, ship traffic and seawater circulation. Among these, waves have so much effect on a breakwater design that it is the most important to understand their characteristics and to apply them to breakwater design. Therefore, to analyze the effect of waves characteristics over a rubble mound breakwater, we have calculated wave pressure by using numerical analysis at each tide level and have analyzed the effect of wave pressure on structure stability by conducting the stability analysis with the wave pressure. As a result, it is found that during low and mean tide level time the biggest wave pressure is estimated near calm water level. But during high tide time, the biggest wave pressure is estimated in front of capping. And the stability analysis indicates also that a structure is most unstable when low tide time wave pressure is acting on. After reviewing the stability of a structure by applying vertical and horizon wave forces, it is concluded that safety factor is lower than ordinary time(max. about 15%), is also reviewed when designing a rubble mound breakwater.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.3
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• pp.236-247
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• 2011

This study investigates sea level (SL) rise due to global warming in the Northwestern Pacific (NWP) and Seas around the Korean peninsula (KP) using outputs of IPCC AR4 climate models. Particularly, components of the SL rise induced by a local steric effect, which was not considered in most climate models, were computed using model-projected 3-dimensional temperature and salinity data. Analysis of the SL data shows that the ratio of the SL rise in the NWP and KP was about two times higher than that in global mean and particularly the ratio in the Kuroshio extension region was the highest. The SL rises over 100 years estimated from MPI_ECHAM5 and GFDL_CM2.1 model by A1B scenario considering the thermosteric effect were 24 cm and 28 cm for the NWP and 27 cm and 31 cm for the Seas around the KP, respectively. Statistical analysis reveals that these SL rises are caused by the weakening of the Siberian High in winter as well as variations of pressure system in the NWP and by the resultant change of water temperature. It also found that the highest SL rise in the Kuroshio extension region of the NWP was connected with the large increase of water temperature in this area.