• Ocean Systems Engineering
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• v.8 no.1
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• pp.1-20
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• 2018

The target area of the proposed study, Mamaia beach, is a narrow stretch of sand barrier island that sits between the Siutghiol Lake and the Black Sea. In the northern part of the bay, is located the Midia Port, where between 1966 and 1971 a long extension of 5 km of the offshore was built. Because of this extension, the natural flow of sediments has been significantly changed. Thus, the southern part of the Mamaia Bay had less sand nourishment which meant that the coast was eroding and to prevent it a protection of six dikes was built. After approximately forty years of coastal erosion, the south of the Mamaia Bay had in 2016 a new protection scheme, which includes first of all the beach nourishment and a new dike structure (groins scheme for protection) to protect it. From this perspective, the objective of the proposed study is to evaluate the effectiveness of the old Master plan against the new one by modeling the outcome of the two scenarios and to perform a comparison with a third one, in which the protection dikes do not exist and only the artificial nourishment has been done. In order to assess the wave processes and the current patterns along the shoreline, a complex computational framework has been applied in the target area. This joins the SWAN spectral phase averaged model with the 1D surf model. Furthermore, new UAV technology was also used to map out, chart and validate the numerical model outputs within the target zone for a better evaluation of the trends expected in the shoreline dynamics.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.3
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• pp.255-269
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• 2023

Surface water temperature of a bay (from the south to the north) increases in spring and summer, but decreases in autumn and winter. Due to shallow water depth, freshwater outflow, and weak current, the water temperature in the central to northern part of the bay is greatly affected by the land coast and air temperature, with large fluctuations. Water temperature variations are large in the north-east coast of the bay, but small in the south-west coast. The difference between water temperature and air temperature is greater in winter and in the south-central part of the bay than that in the north to the eastern coast of the bay where sea dykes are located. As the bay goes from south to north, the range of water temperature fluctuation and the phase show increases. When fresh water is released from the sea dike, the surrounding water temperature decreases and then rises, or rises and then falls. The first mode of empirical orthogonal function (EOF) represents seasonal variation of water temperature. The second mode represents the variability of water temperature gradient in east-west and north-south directions of the bay. In the first mode, the maximum and the minimum are shown in autumn and summer, respectively, consistent with seasonal distribution of surface water temperature variance. In the second mode, phases of the coast of Seosan~Boryeong and the east coast of Anmyeon Island are opposite to each other, bordering the center of the deep bay. Periodic fluctuation of the first mode time coefficient dominates in the one-day and half-day cycle. Its daily fluctuation pattern is similar to air temperature variation. Sea conditions and topographical characteristics excluding air temperature are factors contributing to the variation of the second mode time coefficient.

• Asian Journal of Atmospheric Environment
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• v.6 no.3
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• pp.234-243
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• 2012

The wintertime high loading for atmospheric pollutants is certainly expected in the Byunsan Peninsula of Korea because of a great-scale reclamation project having construction of 33 km tidal sea dike impounding an area of over 40,000 ha and long-range transport. The goal of this study is to trace the origin of this wintertime burden for ambient particulate matter (hereafter called "PM") in the Byunsan Peninsula of Korea. The size-segregated (i.e., cutoff size from 0.01 ${\mu}m$ to 4.7 ${\mu}m$) PM sampling was conducted at a ground-based site of Byunsan Peninsula located in the west coast of Korean Peninsula during the height of dike constructing. Data archived in this study are the mass concentrations of ionic, elemental, and carbonic components in size-fractioned PM. The elemental mass of individual submicrometer particles was also analyzed. The sum of 5-source (i.e., elemental carbon, organic materials, inorganic secondary pollutants, crustal matter, and sea-salts) concentrations shows the bimodal distribution (major and minor peaks formed around $D_p$, 0.65 ${\mu}m$ and $D_p$, 4.7 ${\mu}m$, respectively) by border with 0.19 ${\mu}m$ of cutoff size. The concentrations of EC in $PM_{1.1-0.01}$ in winter and spring times were 4.62 ${\mu}g\;m^{-3}$ and 3.74 ${\mu}g\;m^{-3}$, respectively. Elemental masses of submicron individual particles are classified into two groups, i.e., the major elements (Cl, Al, Si, S, and P) and the minor trace elements. Cluster analysis differentiated the elements in submicron individual particles into 4-cluster. Among them, three clusters are in agreement with the major (Al, Si, S, and P), minor (Fe, Ca, and K), and trace compositions of coal burning. Meanwhile, Cl classified as an independent cluster has different source profile which was mainly due to the Saemangeum seawall project. Some highly toxic elements (e.g., Cr, Mn, and As (and/or Pb)) were also detected in some part of submicron individual PM. As a consequence, the combination of the Saemangeum project and winter monsoon played a considerable part in the double aggravation of wintertime air pollution in the Byunsan Peninsular.

• The Journal of the Petrological Society of Korea
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• v.26 no.2
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• pp.99-112
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• 2017

Geoheritage is designated to preserve geodiversity of geological and geomorphological cases. Geotourism is an extensive activity that aims at the understanding of geology and earth's history for the geoheritage and for developing regions through preserving the geodiveristy of geoheritage. Igidae-Oryukdo is geosite of Busan National Geopark and its visitors are expected to grow rapidly. Accordingly, for the effective use of the geosites, The development and application of geotourism is required. This study suggests that tuffacious sedimentary rocks, hornblende megacrysts-bearing dike, copper mine, marine potholes should designated as the central points for advanced learning stage; volcanic breccia, sea caves, sea cliffs, wavecut platform, tor and islands as the central points for basic learning stage. Based on this central points, this study established concepts for getourism in this study area at basic and expert level for individual and family tourists, and also small or large groups such as school students.

• Journal of the Korean Geosynthetics Society
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• v.14 no.2
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• pp.95-103
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• 2015

In this study, the causes and countermeasures for the leakage of a sea dyke under construction are analyzed. In general, the seabed ground is clearly divided from the embankment but a lot of parts show abnormal zones with low resistivity from the results of electric resistivity survey. Hence the causes of the leakage are considered as following: three-dimensional shear strain behavior, irregular compulsory replacement of the soft seabed ground with low strength and quality deterioration of the waterproof sheets during the closing process. The improvement method is determined by considering the constructability in the seawater and its velocity condition, durability, economic feasibility, similar application cases and so on. Consequently, a combination of low slump mortar and slurry grouting and injection method is selected as an optimum combination. Mixing ratio and improvement pattern are determined after drilling investigation and pilot test. The improvement boundary is separated into general and intense leakage area. The construction is performed with each pattern and the improvement effects are confirmed. The confirmed effects with various tests after completion show tolerable ranges for all of the established standards. Finally, various issues such as prediction of length of the waterproof sheet, installation of it against seawater velocity, etc. should be considered when sea dykes are designed or executed around the western sea which has high tide difference.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.17 no.1
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• pp.47-54
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• 2005

A method has been developed, which can be handled easily and economically for inputting depth data of complex bathymetry and enourmous tidal flats such as Mokpo coastal zone. The method is applied to Chungkye Bay, and some hydrodynamic features related with tidal flat are analyzed. Tidal amplification by construction of the sea-dike and sea-walls had been detected not only near Mokpo Harbor but also at Chungkye Bay which is connected with Mokpo Harbor by a narrow channel. This brings about the increase of tidal flat area, which makes the ebb dominance at Chungkye Bay more seriously. This pronounced ebb dominance with the increase of tidal discharge at the channel between Chungkye Bay and Mokpo Harbor, which results in deepened ebb dominance near Mokpo Harbor as well.

• The Korean Journal of Ecology
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• v.24 no.1
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• pp.27-34
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• 2001

We described the vegetation of a disturbed lagoon wetland in relation to water and soil environments in Kungae lagoon reclaimed 30 years ago. Water depth and soil organic matter showed a great spatial heterogeneity in Kungae wetland which was changed into a freshwater marsh by the dike construction. Detrended canonical correspondence analysis suggested that differences in vegetation structure were primarily the result of variation in water depth or microtopography and soil organic matter Various emergent vegetations were developed in the wetland: species such as Phragmites australis, Calamagrostis epigeios, Carex dispalata and Lythrum anceps in a wide area, hydrophyes such as Typha angustifolia and Scirpus tabernaemontani at the low elevation with deep water, ruderals such as Bidens frondosa and Persicaria perfoliata near upland with much soil organic matter and sand-dune vegetation such as Carex kobomugi, Diodia tens, Pinus thunbergii and Potentilla egedei var. groenlandica at the high elevation. These results suggest that development of a prototype for wetland restoration from vegetation analysis of other natural lagoons and restoration of natural water tables and hydrologic connections between the diked wetland and the sea are important in the disturbed Kungae wetland.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.3
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• pp.115-126
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• 1990

In the past, seawall and sea dike very higher than sea-water elevation had been constructed mainly to prevent the wave overtopping volume. However, the coastal zone is recently developed for the multipurpose of not only preventing from the coastal disaster but conserving the coastal environment and utilizing the coastal space. In this sense, this paper deals with the artificial reef being able to reduce the overtopping volume. Relations of the overtopping volume to the breaking wave are briefly reviewed theoretically, and fundamental factor affecting it are also obtained experimentally form the artificial reef with the irregular waves, In addition, the numerical simulation is developed to investigate the effects of spectral band width for the overtopping volume. The most effective artificial reef section to reduce the overtopping volume is proposed.

• Magazine of the Korean Society of Agricultural Engineers
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• v.33 no.4
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• pp.84-95
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• 1991

The compaction ratio of the field dry density to the maximum dry density is generally adopted as the index of quality control for embankment of earthfill structures such as Earth Dam, Sea Dike, River Bank and Road. In case of coarse materials are included in the earth material, the compaction ratio will be varied in wide range since the dry density is influenced by quantity of coarse material in the soil. The treatment for the coarse material should be controlled carefully in testing. In this study, the compaction characteristics of the soil contained the coarse materials were researched and calibration of the suitability of field quality control methods were carried out. 28 Samples were made of clay(CL) and sandy soil (SM) mixed with gravel whose content were 0, 4, 6, 8, 10, 12, 15, 20, 25, 30, 35, 40, 45, and 60% in Weight. The compaction characteristics depending on the coarse material content were analysed through 4 types of compaction tests which are A-1, B-i, C-i and D-1. The adjusting coefficients for density and moisture content namely a and ${\beta}$ respectively were proposed in order to consider the effects depending on content of the coarse materials. The test methods to control reasonably and promptly the quality of earthfill were proposed after analysing the ranges of possible errors on the relative compaction ratio between laboratory compaction methods and field density testing methods.

• Ocean and Polar Research
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• v.24 no.1
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• pp.39-45
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• 2002

The seasonal patterns of sediment supply were investigated during the period of June 1999 to June 2000 on a coastal foredune of Seungbong Island, Korea. Sediment supply was determined from measurements of geomorphic changes in the foredune and beach along six lines. Most sands were deposited on the dunefoot and foredune area during the winter and spring, from November to April. The largest amount of sands was deposited along the lines 5 and 6 near the sea-dike in the southern tip of the dune area. In general, the sand on the beach was gradually eroded in spring, summer and fall but deposited in winter. Total sediment accumulation over the study period was $484m^3$ for the foredune and $345m^3$ for the beach. The volume of the foredune increased in the winter and spring, whereas the volume of beach increased in the winter. Variation in sediment deposition appears to be controlled primarily by variations in the seasonal wind regime.