• Journal of the Korean Ceramic Society
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• v.46 no.1
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• pp.30-34
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• 2009

A Sand blasting technology has been used to address via and trench processing of glass wafer of optic semiconductor packaging. Manufactured sand blast that is controlled by blast nozzle and servomotor so that 8" wafer processing may be available. 10mm sq test device manufactured by Dry Film Resist (DFR) pattern process on 8" glass wafer of $500{\mu}m's$ thickness. Based on particle pressure and the wafer transfer speed, etch rate, mask erosion, and vertical trench slope have been analyzed. Perfect 500 um tooling has been performed at 0.3 MPa pressure and 100 rpm wafer speed. It is particle pressure that influence in processing depth and the transfer speed did not influence.

• Magazine of the Korean Society of Agricultural Engineers
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• v.28 no.1
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• pp.41-50
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• 1986

This paper attempts to qualitatively characterize scour erosion processes near USGS constriction type-I structures with vertical embankments and abutments. The scour dimensions and rates of sand beds around the structure models were measured in a rectangular flume. The test results showed that scour took place at a rapid rate at initial stages, which were followed by a stage of slow and general scour with greater extends. The maximum scour depth was observed near upstream corner of embankments. Empirical relationships for scour dimensions were derived, that were based on the results from a dimensional analysis of scour processes.

• Journal of The Geomorphological Association of Korea
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• v.19 no.2
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• pp.161-172
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• 2012

The Taeanhaean National Park is located on the middle of the west coast of Korean peninsula. Due to the relatively high wave energy, large tidal range which is about 7m, and extremely complex coastal line, various coastal land-forms such as mud-flats, sand beaches, sand dunes, sea cliffs etc. are well distributed in this area, and thus various coastal ecosystems are well preserved. However, because of reckless sand diggings and construction of artificial structures in the coastal zone, the natural flowing and exchange of coastal deposits were disturbed and the erosion in the beach and the dune has been seriously accelerated. To understand of the causes of these problems, we tried three times periodical measuring with VRS/RTK GPS instrument at the Hakampo and Anmyeon beach. According to seasonal changes of the coast-line, beach area and cross-section of study sites, generally erosion process was dominated in the summer and deposition process was followed after summer.

• Journal of The Geomorphological Association of Korea
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• v.25 no.4
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• pp.37-47
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• 2018

Coastal sand dunes have been regarded as natural defenses to protect hinterland from disasters such as storm surge and typhoons. However, many dunes are not well-deserved in South Korea because of imprudent land development or inappropriate measures after coastal erosion. Lately, beach nourishment and dune reinforcement are emphasized as the effective and environmentally sustainable solution for the coastal protection. They are regarded good strategies to keep landscapes for a time, with little side effects. However, there is little knowledge on the construction methods including proper design and time plans for the best results.In addition, the effects of dune reinforcement in the field should be tested.In thisstudy, we performed sand filling in an eroded dune scarp and surveyed topographic changes in the beach-dune system, which is located along Dasa-ri coast, Chungnam Province, South Korea. Using a network RTK-GPS and drone-based aerial photographs, we analyzed the temporal and spatial changes in the area, before and after the reinforcement. As a result, the dune reinforcement seems to be helpful to mitigates the coastal erosion and to prevent the coastline retreat at least for one year.

• Journal of the Korean Geosynthetics Society
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• v.22 no.2
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• pp.13-21
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• 2023

Mean sea level has recently been rising due to global warming causing coastal erosion. As Korea is peninsula, the land loss due to coastal erosion is critical. An approach in this study is cementing the coastal area using bacteria, which is called microbially induced carbonate precipitation (MICP). This study tried to see how fresh water and sea water work with MICP as a solvent. Ureolytic activity during the MICP reaction was measured with deionized and sea water. A soil column was prepared to evaluate the strength of MICP-treated sand. Sands were treated by MICP with surface percolation method. As the treatmen t style was different with other conventional methods, several methods were proposed to properly evaluate the MICP-treated sand surface. A micro-scale evaluation was performed to assess the mineral structure treated by different solvents. As results, sea water rendered the ureolytic reaction slower. A needle penetrometer worked well to evaluate the MICP-treated sand surface. This study confirmed the utilization of sea water is feasible as the solvent of MICP.

• Geomechanics and Engineering
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• v.17 no.5
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• pp.421-427
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• 2019

Coastal erosion is becoming a significant problem in Greece, Bangladesh, and globally. For the prevention and minimization of damage from coastal erosion, combinations of various structures have been used conventionally. However, most of these methods are expensive. Therefore, creating artificial beachrock using local ureolytic bacteria and the MICP (Microbially Induced Carbonate Precipitation) method can be an alternative for coastal erosion protection, as it is a sustainable and eco-friendly biological ground improvement technique. Most research on MICP has been confined to land ureolytic bacteria and limited attention has been paid to coastal ureolytic bacteria for the measurement of urease activity. Subsequently, their various environmental effects have not been investigated. Therefore, for the successful application of MICP to coastal erosion protection, the type of bacteria, bacterial cell concentration, reaction temperature, cell culture duration, carbonate precipitation trend, pH of the media that controls the activity of the urease enzyme, etc., are evaluated. In this study, the effects of temperature, pH, and culture duration, as well as the trend in carbonate precipitation of coastal ureolytic bacteria isolated from two coastal regions in Greece and Bangladesh, were evaluated. The results showed that urease activity of coastal ureolytic bacteria species relies on some environmental parameters that are very important for successful sand solidification. In future, we aim to apply these findings towards the creation of artificial beachrock in combination with a geotextile tube for coastal erosion protection in Mediterranean countries, Bangladesh, and globally, for bio-mediated soil improvement.

• Journal of Ecology and Environment
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• v.35 no.3
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• pp.167-175
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• 2012

Coastal sand dune systems are particularly fragile and threaten the environment. However, these systems provide fundamental ecosystem services to the nearby urban areas, acting, for example, as protective buffers against erosion. In this paper, we attempt to classify the biotope types of coastal sand dune ecosystems and select an index for the assessment of the conservation value. The types of biotopes are categorized based on the vegetation map; floras are examined in order to research the effects of hinterlands on coastal sand dunes. In addition, a naturalization rate and an urbanization index for each biotope type in hinterlands are analyzed. In the ecosystem of coastal sand dunes, the urbanization index and naturalization rate shows a higher value in sand dunes with areas of road, residential, and idle land in farm villages, rice fields, and fields. On the contrary, a lower value in the urbanization index and naturalization rate is present when typical biotope types, such as sand dune vegetation and natural Pinus thunbergii forests, are widely distributed. Based on these results, urbanization index and naturalization rate should be used as critical indices for the assessment of the ecosystem of costal sand dunes.

• Journal of The Geomorphological Association of Korea
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• v.18 no.3
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• pp.83-92
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• 2011

The properties and changes of geomorphic relief and coastal deposits were analyzed at Goreabul sand beach in Yeongdeok-gun, the largest that in east coast of Kyungsangbuk-do Province. As the result of grain size analysis, in almost season except summer, the sands mainly deposited in Goraebul sand beach because longshore current drift northward contrary to Gangwon-do east coast, and summer longshore current is weak or change direction to south ward. Sand beach mostly came form erosion owing to typoon and storm and was deposit more coarse sand in the summer, and was produced deposition actively in the fall and winter. Front side of sand dune came from deposition on sand every season by sea breeze, especially in the winter.

• Wind and Structures
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• v.27 no.4
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• pp.213-221
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• 2018

In the desert and Gobi regions with strong wind and large sediment discharge, sand transporting engineering is more effective than sand blocking and sand fixing measures in sand prevention. This study uses the discrete phase model of 3D numerical simulation to study the motion trail, motion state and distribution rule of sand particles with different grain diameters when the included angle between the main shaft of the feather-row lateral transportation sand barrier and the wind direction changes, and conducts a comparison in combination with the wind tunnel test and the flow field rule of common sand barrier. According to the comparison, when wind-sand incoming flow passes through a feather-row sand barrier, sand particles slow down and deposit within the deceleration area under the resistance of the feather-row sand barrier, move along the transportation area formed by the transportation force, and accumulate as a ridge at the tail of the engineering. With increasing wind speed, the eolian erosion of the sand particles to the ground and the feather-row sand barrier is enhanced, and the sand transporting quantity and throw-over quantity of the feather-row sand barrier are both increased. When sand particles with different grain diameters bypass the feather-row sand barrier, the particle size of the infiltrating sands will increase with the included angle between the main shaft of the feather-row sand barrier and the wind direction. The obtained result demonstrates that, at a constant wind speed, the flow field formed is most suitable for the lateral transportation of the wind-drift flow when the included angle between the main shaft of the feather-row sand barrier lateral transportation engineering and the wind speed is less than or equal to $30^{\circ}$.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.6_2
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• pp.529-538
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• 2013

Coastline is the most dynamic part of seascape since its shape is affected by various factors. Coastal zone is an area with immense geological, geomorphological and ecological interest. Monitoring coastal change is very important for safe navigation, coastal resource management. This paper shows a result of monitoring coastal morphological changes using Remote Sensing and GIS. Study was carried out to obtain intensity of erosion, deposition and sand bar movement in the Red River Delta. Satellite images of ALOS/AVNIR-2 and Landsat were used for the monitoring of coastal morphological changes over the period of 1975 to 2009. Band rationing and threshold technique was used for the coastline extraction. Tidal levels at the time of image acquisition varied from -0.89m to 2.87m. Therefore, coastline from another image at a different tidal level in the same year was considered to get the corrected coastline by interpolation technique. A series of points were generated along the coastal line from 1975 image and were established as reference points to see the change in later periods. The changes were measured in Euclidean distances from these reference points. Positive values represented deposition to the sea and negative values are erosion. The result showed that the Red river delta area expanded to the sea 3500m in Red river mouth, and 2873m in Thai Binh river mouth from 1975 to 2009. The erosion process occurred continuously from 1975 up to now with the average magnitude 23.77m/year from 1975 to 1989 and 7.85m/year from 2001 to 2009 in Giao Thuy area. From 1975 to 2009, total 1095.2ha of settlement area was eroded by sea. On the other hand, land expanded to the sea in 4786.24ha of mangrove and 1673.98ha of aquaculture.