• 한국전산유체공학회:학술대회논문집
• /
• 2003.10a
• /
• pp.211-212
• /
• 2003

Three dimensional flow above a sand dune has been studied numerically by using Large-Eddy Simulation (LES) method. The movement of the sand which is formed by converging wind directions has been investigated. The numerical method employed in this study can be divided into three parts: (i) calculation of the air flow above the sand dune using MAC method with a generalized coordinate system; (ii) estimation of the sand transfer caused by the flow through the friction; (iii) determination of the shape of the sand surface. Since the computational area has been changed due to step (iii), (i)­(iii) are repeated. The simulated dune, which has initially elliptic cross section, extending at the converging direction which is known as linear dunes.

• Geomechanics and Engineering
• /
• v.2 no.3
• /
• pp.213-227
• /
• 2010

Compacted layers of sand-bentonite mixtures have been proposed and used in a variety of geotechnical projects as engineered barriers for the enhancement of impervious landfill liners, cores of zoned earth dams and radioactive waste repository systems. This paper presents a study on the valorization of local materiel such as dune sand from Laghouat region and mine bentonite intended for the realization of liner base layers in the conception of insulation barriers for hazardous waste centers. In the practice we try to get an economical mixture that satisfies the hydraulic and mechanical properties specified by regulation rules. The effect of the bentonite additions on the mixture is reflected by its capability of clogging the matrix pores upon swelling. In order to get an adequate dune sand-bentonite mixture, an investigation on hydraulic and mechanical behaviours is carried out in this study for different mixtures. Using oedometer test, the adequate bentonite addition to the mixture, which satisfies the conditions on permeability, is found to be around 12% to 15%. These results are also confirmed by direct measurement using triaxial cell.

• Journal of The Geomorphological Association of Korea
• /
• v.26 no.3
• /
• pp.31-42
• /
• 2019

The geomorphological changes of an unvegetated part of the Okjukdong coastal dune were analyzed between 2008 and 2018. Its natural landscape has been destroyed after artificial forestation, but there is no quantitative evidence on these changes. In this study, we measured the unvegetated area using a total station and a network RTK-GPS in 2008, 2014, and 2018. Using Krging method for the three point data sets, we constructed digital elevation models (DEMs) and analyzed topographic changes between the three years. The results showed that the sand of the study area decreased in volume from 2008 to 2014, because sand supply from the nearby beach was blocked by coastal forests. The sand volume temporarily increased from 2014 to 2018, because of the dune nourishment conducted in 2017. It seems that the upper part of the sand dune has shrunk, but the sand at the bottom has increased over the last decade.

• Journal of The Geomorphological Association of Korea
• /
• v.25 no.3
• /
• pp.43-55
• /
• 2018

This study aimed to identify different sedimentary environments of Gochang coast according to geomorphic conditions of each bore hole. To achieve the aim, this study utilized the classification of sedimentary environmental conditions of surface sediment, which was based on grain size distribution characteristics.In other words, three sedimentary environmental conditions ofsandy flat + sand beach, coastal sand dune and weathered bedrock soil, which were distinguished based on grain size distribution characteristics of mean-sorting for surface sediments, were applied to the sediments of bore holes. Four sedimentary environments could be identified in Gochang coast. First, the lake sedimentary environment originated from terrestrial sediments seems to have been dominated by weathered bedrock soil that the surface flow has deposited in a coastal wetland or a boundary, which is affected by the sea. Second, the lake sedimentary environment that is little affected by coastal sand dunes is located at the center of a valley, which is connected to the land, and the dune slack of Saban-ri. The surface flow of weather bedrock soil is the main source of deposits. However, there seems to have been a temporary influence of the sea. Third, the lake sedimentary environment that is strongly affected by coastal sand dunes is located at the dune slack of Yeongjeong-ri. This environment shows traces of a change from a coastal sand dune into the dune slack. Finally, the coastalsand dune sedimentary environment, which wasinvestigated by boring the current coastal sand dune, shows a temporary influence of the land but seems to have maintained the overall stability. Consequently, this study demonstrated that the grain size distribution characteristics of the present surface sediments could be effectively applied to identify the sedimentary environments of the paleo bore hole sediments. In addition, the paleo change of sedimentary environment could also be identified in many places of Gochang coast. If the results of this study are combined with the age dating and geochemical analysis in future works, the paleo environmental change in Gochang coast will be restored more precisely.

• Journal of The Geomorphological Association of Korea
• /
• v.17 no.1
• /
• pp.85-93
• /
• 2010

After the notorious Taean Oil spill in Dec. 2007, a series of sand fences made of fishing net were installed in front of foredune in Shindu dune area. This paper aims to understand the temporal and spatial characteristics of morphological changes of the beach and foredune. About 1m high sand accumulated around sand fences for the last 2 years. While a lot of sand deposited during the winter season (from autumn to spring), small amount of sand eroded and deposited during summer season (from spring to autumn) without big morphological changes. These results mean that sand fences help nature deposit sand near beach and foredune area.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.16 no.1
• /
• pp.55-69
• /
• 2013

The phytosocialogical study on the coastal sand dune vegetation of the East Coast was carried out. 180 phytosociological relev$\acute{e}$s of 62 sites in the East Coast were used in this study. In addition, already published syntaxa and the phytosociological hierarchy in Korea and Japan were used and comparative analyses of syntaxonomy, synecology, syngeography, and syndynamics were performed in the study. In this study, the flora was investigated 30 families, 66 genera, 77 taxa and 3 vegetation types were identified : the coastal drift-line annual communities (Calystegio soldanellae-Salsoletum komarovii), the dune glasslands communities (Elymo-Caricetum kobomugi, Carex kobomugi typical community, Elymus mollis community, Calystegia soldanella community, Zoysia macrostachya community, Cynodon dactylon community, Carex pumila community), and the dune shrubs communities (Linario-Viticetum rotundifoliae, Vitex rotundifolia community, Rosa rugosa community). The aspect of transition in the coastal sand dune vegetation of the East Coast were identified as follows : (1) reduced constancy degree and cover degree of Glehnia littoralis in each community; (2) lack of Ischaemum anthephoroides in Linario-Viticetum rotundifoliae (3) simplified species composition in Vitex rotundifolia community. Unstable habitat condition by external interference seemed to has caused the reduction of 2 taxa, Glehnia littoralis and Ischaemum anthephoroides, that usually grow in the second dune. In addition, we found changes in the distribution of the dune shrub communities influenced by rising temperature of the East Coast as results of the global warming. The results on the distribution of the dune shrub communities in this study demonstrated that the limit of the Rosa rugosa community made $0^{\circ}$ 44'N to the North and the vegetative limit of the Vitex rotundifolia community made $0^{\circ}$ 28'N to the North, respectively compared with the previously phytosociological studies. This study investigated the coastal sand dune vegetation, syntaxonomy, habitat condition and human disturbunce of the East Coast, and this will provide important information as basic data for the coastal ecosystem.

• Journal of the Korean Geotechnical Society
• /
• v.28 no.9
• /
• pp.17-22
• /
• 2012

Wind blown sand is expected to disrupt the operation of the railway as the presented railway project in this paper consists of large earthworks in extreme topography of the mega dune fields. For successful railway construction in sand dune area, effective mitigation measure is the most important factor to protect the track from wind blown sand. The effective mitigation measure requires an integrated consideration of the earthworks geometry and the direct control measures such as fence system. Basically there's no perfect measure protecting railway track from wind blown sand, and it would be more economical and effective to develop robust, deliberate maintenance program for track and direct control measure on the basis of geo-morphological study. The purpose of this study is to identify the large scale geo-morphological terrains and specific sand dune morphology in the project area in UAE and estimate the direction and migration rate for sand dunes with the local variations in prevailing wind directions by undertaking literature review, and aerial photographs, satellite images, and ground studies.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.6 no.6
• /
• pp.29-40
• /
• 2003

Shindoori dune, about 2,000,000$m^2$ in area, is located in the west of the middle area in Korea. Around the sand dune, many diagnostic plants and animals are populated, so it is considered a very important ecosystematic area. This study was carried out to establish for conservation and restoration in Shindoori dune. Our surveys have been accomplished from October, 2002 to September, 2003. Plant communities formed around the sand dune in Shindoori were divided into several patterns and analysed. They have been divided into 9 communities. Community A : Carex pumila community, B : Carex kobomugi community, C : Elymus moWs community, D : Imperata cylindrica var. koenigii community, E: Rosa rugosa community, F: Ischaemum anthephoroides community, G: Vitex rotundifolia community, H : Lathyrus japonica community, I : Oenothera biennis community. The flora surveyed in these communities was constituted of 19 families, 44 genera, 8 varieties, and 40 species. Wild plants such as Calystegia soldanella, Artemisia capillaris, Avena fatua, Mertensia asiatica, Glehnia littoralis and Zoysia sinica were mostly light loving plants and higher resistant plants against the salty wind. Our result from the ranking all surveyed areas by the Bray-Curtis ordination method was very similar to the results from phytosocialogical table work.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.15 no.1
• /
• pp.9-16
• /
• 2013

Coastal sand dune area is an important ecosystem as an ecotone which is located between coastal area and terrestrial area. In order to understand the sand dune ecosystem in terms of its habitat characteristics, micrometeorological analysis was carried out in a coastal sand dune in Hakampo, Taeanhaean National Park, Korea. Micrometeorological measurements were made to monitor air and soil temperatures, relative humidity, soil water content, rainfall, solar radiation, wind speed, and wind direction. In contrary to a forest ecosystem, the coastal sand dune grassland ecosystem was relatively hotter and very humid with heavy rainfalls concentrated between June and July. The seasonal change of daily mean soil temperature was greater than that of air temperature by $2{\sim}3^{\circ}C$. Daily mean soil water content was less than 10% throughout the year. Also, the maximum wind speed of 156.7 m $s^{-1}$ was recorded on 7 October 2011. The observed seasonal wind direction was different from those observed at Seosan by KMA (Korea Meteorological Administration). To better understand the habitat characteristics in a costal sand dune grassland ecosystem, long-term multi-year measurements are needed.

• Journal of the Economic Geographical Society of Korea
• /
• v.12 no.4
• /
• pp.702-717
• /
• 2009

This study estimates the willingness-to-pay(WTP) for conserving Sindu coastal sand dune and asset value of Sindu coastal sand dune by means of contingent valuation method. CV market scenario is designed to elicitate his/her WTP considering use value and nonuse value of Sindu coastal sand dune. The yearly WTP for Sindu coastal sand dune is 3,059 won(95% C.I. 2,591~3,612 won) in the case of a househodl, therefore amounts to 44 billion won(95% C.I. 37~52 billion won) for the whole nation. We estimate the asset value of Sindu coastal sand dune by 7.5% discount rate to be 587 billion won with 95% confidence interval of 497 to 693 billion won. The direct use value which has accounted for 13.4% is 79 billion won(95% C.I. 67~93 billion won), and the indirect use value which has accounted for 30.2% amounts to 177 billion won(95% C.I. 150~209 billion won), and the option value which has accounted for 19.4% is 114 billion won(95% C.I. 97~135 billion won), and the conservation value which has accounted for 37.0% amounts to 217 billion won(95% C.I. 184~256 billion won).