• Journal of The Geomorphological Association of Korea
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• v.19 no.3
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• pp.71-82
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• 2012

This research was carried out to estimate annual erosion and retreat rates by using datum-point and to identify the characteristics and causes of seasonal variations of sea-cliff slope in Pado-ri, Taean-gun. In the result, the erosion and retreat rates of sea-cliff were increased from spring to summer. The rates were increased rapidly between August and October, caused by the effects of extreme weather events such as severe rainstorms and typhoons, etc. Since then, the erosion and retreat rates of sea-cliff were decreased gradually, but the rates were increased again in winter due to the storm surge and mechanical weathering resulting from the repeated freezing and thawing actions of bed rocks. The factors that affect erosion and retreat rates of sea-cliff include the number of days with antecedent participation and daily maximum wave height. In particular, it turned out that the erosion is accelerated by strong wave energy during storm surges and typhoons. The annual erosion and retreat rates of study area for the past two years(from May 2010 to May 2012) were approximately 44~60cm/yr in condition of differences in geomorphological and geological characteristics at each point. These erosion and retreat rates were found to be higher than results of previous researches. This is caused by coastal erosion forces strengthened by extreme weather events. The erosion and retreat process of sea-cliff in the study area is composed by denudation of onshore areas in addition to marine erosion(wave energy).

• Journal of the Korean earth science society
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• v.22 no.4
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• pp.317-326
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• 2001

The coastline of semi-enclosed Hampyung Bay, southwestern coast of Korea, consists largely of erosional sea-cliffs characterized by steep face slope, low in height (less than 3m), and composition of soft reddish soil. Recession rates of the sea-cliffs in the Haeuri coast of Hampyung Bay, which were Quantified by photogrammetry using single aerial photographs taken 1976 and 1990, respectively, were approximately 1${\sim}2m/yr. This value is in good agreement with the field measurement conducted by Chang et al. (1999). Subsequently, the photogrammetry seems to be a very useful method to measure easily long-term coastline change. This severe erosion of sea-cliff in the semi-enclosed bay environment, furthemore, is probably due to combined effects of typhoon or/and storm surges and weak resistance of soil cliff itself.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.4
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• pp.197-206
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• 2014

The purpose of this study is to evaluate coastal erosion due to a sea-level rise. The shoreline retreat rate was calculated due to future sea-level rise. Shoreline retreat rates were quantified with the cross-sectional data of 23 sandy coasts (12 sites from east coast, 5 sites from south coast, and 6 sites of west coast) and 3 cross-sectional profiles from each side of the coasts in Korea. The theory of equilibrium beach profile was employed in this study to evaluate the applicability of the theory into the coast of Korea and was tested with 15 cross-sectional beach profiles. Four scenarios of future sea level rise such as 38 cm, 59 cm, 75 cm, and 100 cm were adopted to estimate the shoreline retreat rates. Overall shoreline retreat rates for the coasts in Korea were predicted as 43.7% for 38 cm, 60.3% for 59 cm, 69.2% for 75 cm, and 80.1% for 100 cm sea level rises, respectively. Retreat rates in the east coast (29.6% for 38 cm, 45.1% for 59 cm, 56.0% for 75 cm, and 69.9% for 100 cm) showed relatively low compared to the south coast (51.9%, 67.6%, 77.2%, 87.3%) and the west coast (53.8%, 71.0%, 78.5%, 86.4%). However, all sandy coasts in Korea were assessed to be vulnerable with increasing sea-level rise. There are uncertainties in the assessment of this study, which include the limitation of the assessment model and the lack of the spatio-temporal data of the beach profiles. Therefore, this study shows that it is very important to spend integrated efforts to respond coastal erosion including comprehensive observations(monitoring) and the development of scientific understanding on the field.

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.4
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• pp.266-273
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• 2016

Two-dimensional hydraulic experiments were performed to assess the impact of artificial seaweed on wave energy attenuation, and coastal erosion prevention. In this experimental study, erosion geometry and wave reflection coefficients were determined for normal and stormy incident waves, with and without artificial seaweed. The coastline of beaches without artificial vegetation was observed to retreat, and the longshore bar height increased in normal and stormy conditions. Through the introduction of artificial seaweed (of widths 0.8 m, and 1.6 m), the coastline was found to advance in the offshore direction due to material deposition. From these results, it is shown that artificial seaweed alters the cross-section of beaches, such that it is possible to prevent coastline erosion.

• Journal of the Korean earth science society
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• v.26 no.6
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• pp.584-596
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• 2005

Morphology, surface sediments, sedimentation rates and sea-cliff erosion have been monitored, for one year to investigate the shoreline changes and tidal beach characteristics in Cheonsu Bay along the west coast of Korea. The seacliff of the bay consists of intensively weathered sedimentary rocks and soft soil, showing an erosion range of $-58.9\~73.3cm/yr$ by a weak wave forcing. Active sea-cliff erosions are recognized by peculiar geomorphic features, including saw teeth-shaped coastline, gravels, relict weathered basement-rock and 'Island Stack' exposed on the high-tide beach surface. The beach sediments show low compositional maturity at the south and north headlands and gradually high towards the central part. This observation seems to be caused by the fact that beach sediments are to originate from the both headlands in the study area and then transported by long-shore current associated with a wave action.

• Korean Journal of Remote Sensing
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• v.29 no.5
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• pp.477-486
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• 2013

To analyze tendency of temporal and spatial change of shorelines and to estimate rate of shoreline changes using long-term shoreline change data is very important for the coastal environmental management. In this study, investigation was conducted to estimate the rate of shoreline changes using long-term shoreline change data from the year 1985 to 2009 aerial photographs. In this process aerial triangulation, GPS surveying and digital mapping was done for the estimation of changes. As the results, shorelines of Bangpo and Kkotji Beach retreated at a maximum rate of 0.2 m/yr and 0.8 m/yr, respectively. The shoreline could be changed by various factors. However, it was presumed that coastal erosion has been mainly affected by retaining wall constructed in the late 1990s.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.2
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• pp.117-126
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• 1999

Hampyong Bay is a semienclosed and macrotidal bay which opens to the eastern Yellow Sea through a narrow inlet in the southwestern coast of Korea. In order to understand the tidal-flat sedimentation in the semienclosed setting, morphology, sediments, accumulation rate and sea cliff erosion were investigated in the tidal flat of Hampyong Bay. The tidal flat of Hampyong Bay lacks intertidal drainage systems, and generally shows the concave-upward profile whose relief is designated by marked morphological features such as high-tide beaches, intertidal sand shoals and tidal creeks. Surfacial sediments of the tidal flat mainly consist of mud, sandy mud, gravelly mud, gravelly sand and muddy gravel, thus showing the textural characteristics of multimodal grain-size distribution, poorly sorting and positive skewness. The sediments generally coarsen landward due to the increase in coarse fraction content. Sedimentary structures are deeply bioturbated, but parallel lamination and lenticular bedding are locally found in the mudflat near mean low water line. Annual accumulation rates across the tidal flat (along Line SM) average -5.2 cm/yr with a range of -45.8~+4.2 cm/yr, indicating that the tidal flat is erosional. In general, erosion rates of upper and lower tidal flat are higher than those of middle tidal flat. Seasonally, the erosion rates are much higher during spring and winter when dominant wind direction corresponds to the long axis of Hampyong Bay. Sea cliffs are eroded at a rate of 1.4 m/yr. The biggest sea cliff erosion generally occurs 1~2 months later after tidal flats were extensively eroded. Such erosions of tidal Oats and sea cliffs in the semienclosed bay setting are interpreted to be due to wind waves coupled with local sea-level rise.

• Korean Journal of Remote Sensing
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• v.33 no.6_1
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• pp.971-980
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• 2017

In this research, it was presented that the strategic approach for the long-term shoreline changes using historic digital aerial images can be effective for the analysis on the bangameori beach, west coast of South Korea. For this purpose, we collected several historic digital aerial images over 9 years in the research filed and conducted GPS-VRS surveying for GCP (Ground Control Point) acquisition. Also we collected existing two dimensional shoreline digital map which was published by KHOA (Korea Hydrographic and Oceanographic Agency) in the year 2013. With these multi data sets, we provided quantitative analysis on coastal erosion using the long-term shoreline changes in the beach. Also, As the results it was found that 2m sea level was retreated in the research period with maximum 0.31m length.