• Journal of Wetlands Research
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• v.13 no.1
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• pp.45-52
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• 2011

Seawater circulations between a bay and the open sea play an important role to make the ecosystem healthy, providing nutrient and oxygen to the benthic environments and cleaning up pollutions. The health of the benthic environment in a bay is closely related to the flushing characteristics of seawater. In this study, to estimate the seawater distribution and circulation characteristics of benthic environment in the Geunso bay, we calculated the hydraulic turn-over time by a hydro-hypsographic analysis. Digital elevation model (DEM) which was generated using waterline method based upon remotely sensed data and water depth of the subtidal zone estimated by echo-sounding survey was applied to the hydro-hypsograhic analysis through a geographic information system (GIS) spatial analysis. The results showed that 95% of the total area of the bay was tidal flat and the hydraulic turn-over time was 1.03 tidal cycle, which indicated that the flushing characteristics of the Geunso bay was very good. Geunso bay was revealed to occupy relatively wide area of benthic environment and to have relatively big tidal range over other domestic and foreign coastal environment, therefore it could have a better seawater circulation characteristics. This result can be effectively applied as fundamental information to establish the system for a quantitative estimate of health of coastal environment in the west coast of Korea and manage the ecosystem in benthic environments.

• Journal of Korea Water Resources Association
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• v.47 no.9
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• pp.753-766
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• 2014

The future mean sea level rise (MSLR) due to climate change in major harbors of Korean Peninsula has been estimated by some statistical methods in this article. Firstly, Mann-Kendall non-parametric trend test to find some trend in the observed long-term tidal data has been performed and also Bayesian change point analysis has been used also to detect the location of change points and their magnitude quantitatively. Especially, in this study, the results from Bayesian change point analysis have been applied to combine 4 future MSLR scenario projections with local MSLR data at 5 tidal gauges. This proposed procedure including Bayesian change point analysis results can improve the step for the determination of starting years of future MLSR scenario projections with 18.6-year lunar node tidal cycle and effectively consider local characteristics at each gauge. The final results by the proposed procedure in this study have shown that the future MSLR in Jeju region (Jeju tidal gauge) is in the largest increment and also the future MSLRs in Western region (Boryeong tidal gauge) and Southern region (Busan tidal gauge) are in the second largest one. Finally, it has been shown that the future MSLRs in Southern region (Yeosu tidal gauge) and Eastern region (Sokcho tidal gauge) seem to be in the relatively smallest growth among 5 gauges.

• Ocean and Polar Research
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• v.36 no.1
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• pp.25-37
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• 2014

To understand the degradation processes of organic matter related to sulfate reduction by Sulfate Reduction Bacteria (SRB) in the tidal flat sediments of Hwang-do and Sogeun-ri, Tae-an Peninsula in Chungnam-do, biogeochemical characteristics were analyzed and highlighted using specific microbial biomarkers. The organic geochemical parameters (TOC, ${\delta}^{13}C_{org}$, C/N ratio, long-chain-n-alkane) indicate that most of the organic matter has been derived from marine phytoplankton and bacteria in the fine-grained sediment of Sogeun-ri, although terrestrial plant components have occasionally been incorporated to a significant degree in the coarse-grained sediment of Hwang-do. The concentration of sulfate in pore water is a constant tendency with regard to depth profile, while methane concentration appears to be slightly different with regard to depth profile at the two sites. Especially, the sum of bacteria fatty acid (a-C15:0 + i-C15:0 + C16:1w5) confirms that the these concentrations in Sogeun-ri are related to the degradation of Benzene, Toluene, Ethylbenzene and Xylene (BTEX) compounds from the crude oil retained in the sediments as a result of the Hebei Spirit oil-spill accident in 2007. The methane-related microbial communities as shown by lipid biomarkers (crocetane, PMI) are larger in some sedimentary sections of Hwang-do than in the Sogeunri tidal flat. These findings suggest that methane production by microbiological processes is clearly governed by SRB activity along the vertical succession in organic-enriched tidal flats.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.19 no.1
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• pp.33-39
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• 1983

Tidal exchange of sea water was studied by using drogue experiments and tidal current measurement data in Yeoja Bay which has a narrow channel. At the spring tide, the volume of tidal transport in the bay was estimated to be 43% of the mean volume of the sea water in Yeoja Bay, 1.96km super(3). Residual current was deduced to flow southward at the rate of 3,658$\times$10 super(4) m super(3) per tidal cycle. The mean tidal exchange of sea water during the flood flow was estimated to be approximately 5.0% of the volume of sea water at the mean high water level in the bay, 2.33km super(3), while that during the ebb flow was 6.3%. One dimensional diffusion coefficient of 1.69-1.97$\times$10 super(6) cm super(2)/sec was obtained at the channel in the bay.

• Journal of The Korean Astronomical Society
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• v.24 no.1
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• pp.117-127
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• 1991

Here I report the confirmation of a long-term modulation of a period of $92^{+21}_{-13}$ years with the "time-delay correlation" method on the sunspot data compiled over the last a total of 289 years. This periodicity better specifies the cycle which falls pretty well within Gleissberg cycle, and clearly contrasts with the 55 year grand cycle which Yoshimura (1979) claimed. It is argued that the period-amplitude diagram method. which Yoshimura used, ana lysed peak amplitudes only so that a large number of data were disregarded, and thus was more susceptible to a bias. The planetary tidal force on Sun as for the possible cause to the solar activity was investigated and its possibility was ruled out in view of no period correlation between them.

• 한국해양학회지
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• v.11 no.1
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• pp.9-17
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• 1976

Multispectral scanner data collected by LANDSAT-1 over the mid West Sea of Korea were analyzed and interpreted for delineation of coastal features and turbidity distribution patterns during different portions of the tidal cycle. Imagery from two successful LANDSAT-1 overpasses of the area in October 1972 and in October 1973 had been used to prepare schematic maps of coastal features and turbidity distributions. Color composite imagery of LANDSAT MSS 4, 5 and 7 gave the best representation of shorelines, coastlines and tidal flats. MSS 5 imagery was most effective in differentiating relative turbidity levels through density slicing techniques. Referring to the tidal power development of Garolim Bay, the basin area measurements assuming dyke construction at the bay entrance, have been carried out on the coastal reature maps comiled from LANDSAT imagery, and those results were correlated with existing data. General areal patterns of surface turbidity distribution in the study area revealed close similarity with bathymetry of the area. Synoptic circulation patterns were also well discriminated from the LANDSAT imagery using the suspended sediment as a tracer.

• Journal of the korean society of oceanography
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• v.37 no.3
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• pp.144-153
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• 2002

This is a review paper, assessing progress reported in a Special Issue (Prandle and Lane, 2000) of Coastal Engineering focusing on simulation of SPM in the North Sea, against issues over a diverse range of shelf seas and their coastal margins. The broad objectives of reproducing the characteristics of sediment fluxes off an open coast and relating these to tidal and wave forcing were achieved. However, accurate computation of these fluxes remains sensitive to largely empirical coefficients used in determining erosion and deposition rates. Bed roughness strongly influences both these coefficients and the associated near-bed current magnitudes (including wave impact thereon). Bed roughness can change significantly over a tidal cycle and dramatically over seasons or in the course of a major event. Accurate simulation of sediment fluxes on a day-to-day basis is constrained by dependency on the initial distribution of mobile sediments. The latter depends on rates and locations of original sources and the time history of preceding events. Remote sensing via aircraft could provide data for assimilation into such models to circumvent these constraints. The approaches described here can be readily applied to other coastal regions to indicate the likely distributions and pathways of known sediment sources. However quantitative simulations will require an associated observational programme. A subsequent stage is to understand the evolving balance between the forecasted sediment movement - the resulting morphological adjustments and thence modifications to the prevailing tidal current and wave regimes.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.4
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• pp.289-296
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• 2009

The appearance and variation of cold water area and its expansion mechanism of tidal front in the south western coast of Korea in summer were studied on the basis of oceanographic data(1966-1995), satellite images from NOAA and SeaWiFs and numerical model. Cold water appearance in southwestern field of Jindo was due to the vertical mixing by strong tidal current. Tidal front where horizontal gradient of water temperature was more than $0.3^{\circ}C$/km parallels to contours of H/$U^3$ parameter 2.0~2.5 and the outer boundary of cold water region corresponds with contours of the parameter 2.5~3.0 in the southwestern sea of Korea during the period between neap and spring tides. The position replacement of tidal front formed in the study ares varies in a range of 25~75km and cold water region extends about 90km. These suggest that the magnitude of variation of frontal position and cold water area was proportionate to the tidal current during lunar tidal cycle. Moreover, it was estimated that the southwestward expansion of cold water region was derived from the southwestward tide-induced residual currents with speed more than 10cm/s.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.60-61
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• 2013

For reinforced concrete structures located in a sea environment, the Impressed Current Cathodic Protection (ICCP) is mostly used as a signature method to prevent steel corrosion. For this research, specimens to which the ICCP is applied were manufactured under the assumption of two following cases the specimens are exposed to various salt damage environments (submerged zone, tidal zone), and deteriorative factors (crack) occur in concrete. For the specimens manufactured, an enhancement experiment for deterioration was conducted through regular cycle change under the temperature between 15 ~ 70℃ with 70 ~ 90% humidity. Afterwards, the method effect was verified through a half-cell method and application of the ICCP derived from salt damage environments was investigated.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.2
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• pp.41-51
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• 2013

The tidal creek dependent mass transport characteristic in Gyeong-Gi Bay (west coast of Korea) was studied using field measured data and numerical model. Gyeong-Gi Bay consists of 3 main tidal channels and contains a well-developed vast tidal flat. This region is famous for its large tidal difference and strong current. We aim to study the effect of tidal creek in the tidal flat on the mass exchange between the estuary and the ocean. For numerical application, the application of unstructured grid feature is essential, since the tidal creek has complicated shape and form. For this purpose, the FVCOM is applied to the study area and simulation is performed for 2 different cases. In case A, geographic characteristics of the tidal creek is ignored in the numerical grid and in case B, the tidal creek are constructed using unstructured grid. And these 2 cases are compared with the field measured cross-channel mass transport data. The cross-channel mass transport at the Yeomha waterway mouth and Incheon harbor was measured in June, 9~10 (Spring tide) and 17~18 (Neap tide), 2009. CTD casting and ADCP cross-channel transect was conducted 13 times in one tidal cycle. The observation data analysis results showed that mass transport has characteristic of the ebb dominance Line 1 (Yeomha waterway mouth), on the other hand, a flood dominant characteristic is shown in Line 2 (Incheon harbor front). By comparing the numerical model (case A & B) with observation data, we found that the case B results show much better agreement with measurement data than case A. It is showed that the geographic feature of tidal creek should be considered in grid design of numerical model in order to understand the mass transport characteristics over large tidal flat area.