• KCID journal
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• v.19 no.1
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• pp.3-18
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• 2012

In recent years, as environmental problems have become great concerns among many people, th loss of beach sand has become one of the highly controversial issue. Major reasons for the beach erosion within the cases of West Coast can be classified as: 1) erosion at Unyeo, Baeksajang beaches are caused by the wave refraction according to the large-scale sand dredging, 2) erosion at Kkotji, Baeksajang, and Unyeo beaches are caused by large-scale embankment construction and the coastal road construction, and 3) erosion at Chollipo and Hakampo beaches are caused by construction of small ports. Erosion in the west coast of Korea coast beach erosion control measures, include groin, zeotube, terraced stone, jetty groin, and beach nourishment. Erosion control measures initially installed to prevent erosion showed a positive effect. However, if there is no continuous source of sand, the effect of measures is fewness.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1350-1355
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• 2004

주택건설과 대규모 개발사업으로 인해 골재부족이 심화되면서 하천정비공사에서 골재채취가 주요한 사업이 되고 있다. 하지만 무분별한 골재채취는 하천생태계를 파괴시키는 원인이 된다. 본 연구는 하천에서 골재를 채취할 때 수생태계에 미치는 영향과 골재채취를 중지하고 휴식년제를 취할 때의 수생태계에 미치는 영향을 서로 비교${\cdot}$분석함으로서 하천골재 채취가 환경에 미치는 영향을 분석하였다. 연구방법은 수리학적 분석, 수질분석, 생태학적 분석을 이용하였다. 연구대상지역은 영산강의 일부구간으로 현재 이 구간은 골재채취공사가 진행중인 지역이다. 하상변동을 수치해석으로 모의한 결과 하상은 골재채취후 안정적으로 유지될 것으로 분석되었으며 골재채취가 수질에 미치는 영향은 그리 크지 않았고 단지 부유사(SS)가 약간 증가하였다. 생태학적 조사 결과 어류, 포유류, 양서류, 파충류와 조류는 공사로 인한 영향을 많이 받고 있는 것으로 분석되었다. 본 연구의 결과는 골재채취 사업에 따른 환경영향평가 및 사전환경성 검토에 활용될 수 있고, 하천공사와 수공구조물의 설계 및 유지관리 등에도 활용될 수 있을 것이다.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.974-979
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• 2008

The purpose of this study was to evaluate the effect of vegetation on the cutting slope applied by vegetation system in the whole land. The engineering characteristics of slopes were investigated using the face mapping and physical tests. From the statistical methods, a relationship between a geologic stratum and degree of covering was independent. Therefore, the afforestation of slope was affected more by condition of vegetation as direction and opening of joints, and a topsoil state than by conventional classification of layer. It was concluded that the adjustable vegetation on the slope considering condition of geometric shape of slope, joint data and spontaneous type could make useful early afforestation.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.483-490
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• 2002

A massive amount of marine clay produced as dredging of coast and sea bed is often dumped in open sea and filled in pond. The treatment of marine clay demand a large area and make fatal environmental problems for echo system. This research work intend to manufacture a light-weight landfill materials which are produced by mixing the dredged marine clay with various amount cement and foam. An extensive Uniaxial and Triaxial compression test are carried out to investigate the strength characteristics of the light-weight cement mixed marine clay with foam under various test conditions. The results indicated that the required unit weight has been achieved with negligible change after 28days curing time in water. It is also recognized that the compressive strength of light-weight landfill materials linearly decrease with increasing initial water content, and the rate of strength decrease with increasing initial water content in water curing was smaller than that of air curing Futhermore, the rate of strength decreased with increasing initial water content, however, the rate become smaller as cement content increased.

• Journal of Environmental Impact Assessment
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• v.19 no.2
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• pp.107-116
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• 2010

In this research potential liquation of contaminants from surrounding soil to a reservoir in an island was studied to investigate the cause and route of contamination of Baengyeong-myeon reservoir. Soil of Baengyeong-myeon reservoir consists of $SiO_2$ and has a high iron content because of geological characteristics of its country rock. From the field investigation and simulation study it was found that highly accumulated carbon content in the reservoir sediment was incurred from ground water, which provides a good habitat for microbes. And the liquation, the cause of organics growth, occurs mainly on the bottom of the reservoir consisting marine clay layer once used as farmland. So dredging of the sediment of reservoir and replacing with valley soil is suggested to prevent continuous contamination of a reservoir in an island due to COD production.

• Journal of the Korean GEO-environmental Society
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• v.5 no.4
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• pp.5-11
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• 2004

When settled sediments in natural condition for long time were dredged by dredging process, it is natural that bulking change between sediments and dredged soils is affected by chemical injection; coagulant. Dredged sediments used in this study were sampled in the lagoon "Young rang lake" located at the east coast Sokcho city and the bulking change of dredged soils is quantitatively analysed by changing of the clay content and the amount of the flocculant and coagulant. From the experimental results, the bulking of dredged soils increased 1.69 times on the average bulking of settled sediments in natural condition in the case of the optimum chemicals addition.

• Journal of Environmental Science International
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• v.25 no.8
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• pp.1191-1206
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• 2016

Transported deposit was accumulated in a grit chamber built at the mouth of Yeocheoncheon in 1987 with the intention of blocking the influx of sediment into the Ulsan-harbor. This study attempted to analyze the effects of the transported deposit on the water quality at Yeocheoncheon. Only one episode of dredging has been performed in the approximately 25 years since the grit chamber were built, leading to the formation of stagnant water in the grit chamber due to a large amount of transported deposit. The deposit has a relatively high organic content, in the range of 11.7-25.9% (mean 18.3%). It appears that the main reason for the upstream transport of water pollution from the mouth of the Yeocheoncheon is the tides. The effects of organic content and stagnant water on water quality were analyzed using WASP. Moreover, the changes in water quality arising due to the removal of the grit chamber were analyzed. Results indicated that BOD improved by 18.8-100%, while T-P improved by 90.0-617.4%, between the grit chamber and Hanbi-Gyo, which is located 1.3 km away from the grit chamber.

• Journal of the Korean Society of Safety
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• v.33 no.2
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• pp.132-137
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• 2018

Compared with general rivers, fluctuations of the water level and the river bed are severe in the tidal river. In hydro-dynamic aspect, such fluctuation gives different river-bed data to us according to observing period. The time-dependent river-bed data and pre-estimation of the Manning's roughness coefficient which is the key factor of numerical modelling induces uncertainty of evaluating the design flood level. Thus it is necessary to pay more attention to calculate the flood level at tidal rivers than at general rivers. In this study, downstream of the Imjin River where is affected by tide of the West Sea selected as a study site. From the numerical modelling, it was shown that the unsteady simulation gave considerable mitigation of the water level from the starting point to 15 km upstream compared to the steady simulation. Either making a detention pond or optional dredging was not effective to mitigate the flood level at Gugok - Majung region where is located in the downstream of the Imjin River. Therefore, a more sophisticated approach is required to evaluate the design flood level estimation before constructive measures adopted in general rivers when establishing the flood control plan in a tidal river.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.6
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• pp.87-95
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• 2011

This study investigates Youl Chon Industrial Complex 1 by dividing into three regions : the drainage site, the area inside the complex, and the seaside. Then each region was subdivided into three areas resulting in a total of nine areas for soil sampling and analysis. After analyzing the physical and chemical properties of the soil, all nine area's pH and EC readings indicated that the soil condition is not suitable for vegetation growth (according to the previous study, the pH level was 5.8 and EC was 2.0dS/m). Therefore, for Youl Chon Industrial Complex 1 to become green, the neutralization and reduction of pH and EC level is needed; first, vegetation through dredging soil, and second, introduction of halophytes is suggested. This study finds out that vertical changes in physical and chemical properties of soils in reclaimed sites are very variable and the result depends on surrounding environments, so it suggested the basic data for building vegetation or reclaimed sites. However, the additional study aiming at various reclaimed sites is required as this study was conducted only to limited areas, and this study has left monitoring analysis as the follow-up task to check the relations between a plant community and soils.

• Journal of the Korean GEO-environmental Society
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• v.8 no.1
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• pp.27-32
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• 2007

Trafficability for construction equipments in soft ground should be secured by improving the surface course. For this situation, the ground improvement technique has been used with stiffening agent, but the improvement cement has been mostly used so far. However, oyster shell has been developed and used as the stiffening agent to expand the chance of recycling oyster shell, which is regarded as solid waste. In this research, it was confirmed mechanical characteristics of oyster shell as stiffening agent by analyzing the strength characteristic such as mixing rates, water contents, and curing days of that to the dredging soil.