• Korean Journal of Environment and Ecology
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• v.28 no.4
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• pp.442-449
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• 2014

This study was carried out to measure the seasonal changes in community structure and species composition of marobenthos on the subtidal area of Saemangeum regions. The macrobenthos comprised 64 species were during this study, predominately annelids (53.0%), arthropods (18.8%), mollusks (18.8%) and 9.4% were from other species. Total abundance was 24,885 individuals, comprising 19,805 individuals of annelids (79.6%), 4,620 individuals of mollusks (18.5%), 295 individuals of other species (1.2%), and 165 individuals of arthropods (0.7%). After analyzing the bray-curtis similarity, had two large groups (A, B) the inside and outside of Saemangeum dike. They all matched the nMDS analysis. I evaluated the benthic community health using BPI (Benthic pollution Index). There are no significant differences between the station position and the inside or outside of Saemangeum dike. But, highest BPI level was in March.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.2
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• pp.113-128
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• 1990

In recent years, various types of coastal protection scheme have been studied around the coastal region. Among them, so-called zonal protection systems are being watched with interest from various points of view. In this paper, wave overtopping rate from overflowing the vertical seawall is investigated by conducting two dimensional model on the horizontal bed experiment. Hereafter this system is referred to as a artificial reef system. One is the foundation to control wave height near the surfzone and the other is function to prevent coastal disaster by suppressing net overtopping rate. The main results obtained in this study are summarized as follows. 1) Wave attenuation taken place on the artificial reef can be predicted numerically by using energy dispersion model due to wave breaking proposed by Battjes. 2) To evaluate the wave overtopping rate from a vertical seadike on various coastal constructions by weir model, a numerical procedure for prediction of overtopping is confirmed.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.3
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• pp.266-273
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• 2007

The change patterns of the water quanity, water quality(WQ, exclusively COD in this study) and monthly / annual pollutant loads(PL) estimated using the daily effluent discharges and WQ measurement data are analyzed in the Nakdong river estuarine seadike. The contribution factor defined by the ratio of the water quantity range and WQ range shows that the PL pattern in this estuary is classified as the strongly flow(water quantity)-dominated situation. The estimated PL(EPL)s with respect to the increasing sampling periods, e.g., 2-days, 5-days, 7-days, and so on, show that the mean values of the EPLs remain nearly same, whereas the standard deviations of the EPLs have an obvious increasing trend. The PL values using the monthly-averaged water quantity and WQ measurement data could have approximately 100% estimation error in annual mean and $300\sim400%$ estimation errors in summer season because its confidence level is relatively low. It is recommended that the PL should be estimated using at least $10\sim20$ day interval data sets and also the water quantity(river discharges) and WQ should be measured at the intervals of at least 1 day interval and 5 to 7 days, respectively in summer.

• Magazine of the Korean Society of Agricultural Engineers
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• v.13 no.4
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• pp.2456-2470
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• 1971

Compaction of soil is very important for construction of soil structures such as highway fills, embankment of reservoir and seadike. With increasing compaction effort, the strength of soil, interor friction and Cohesion increas greatly while the reduction of permerbilityis evident. Factors which may influence compaction effort are moisture content, grain size, grain distribution and other physical properties as well as the variable method of compaction. The moisture content among these parameter is the most important thing. For making the maximum density to a given soil, the comparable optimum water content is required. If there is a slight change in water content when compared with optimum water content, the compaction ratio will decrease and the corresponding mechanical properties will change evidently. The results in this study of soil compaction with different water content are summarized as follows. 1) The maximum dry density increased and corresponding optimum moisture content decreased with increasing of coarse grain size and the compaction curve is steeper than increasing of fine grain size. 2) The maximum dry density is decreased with increasing of the optimum water content and a relationship both parameter becomes rdam-max=2.232-0.02785 $W_0$ But this relstionship will be change to $r_d=ae^{-bw}$ when comparable water content changes. 3) In case of most soils, a dry condition is better than wet condition to give a compactive effort, but the latter condition is only preferable when the liquid limit of soil exceeds 50 percent. 4) The compaction ratio of cohesive soil is greeter than cohesionless soil even the amount of coarse grain sizes are same. 5) The relationship between the maximum dry density and porosity is as rdmax=2,186-0.872e, but it changes to $r_d=ae^{be}$ when water content vary from optimum water content. 6) The void ratio is increased with increasing of optimum water content as n=15.85+1.075 w, but therelation becames $n=ae^{bw}$ if there is a variation in water content. 7) The increament of permeabilty is high when the soil is a high plasticity or coarse. 8) The coefficient of permeability of soil compacted in wet condition is lower than the soil compacted in dry condition. 9) Cohesive soil has higher permeability than cohesionless soil even the amount of coarse particles are same. 10) In generall, the soil which has high optimum water content has lower coefficient of permeability than low optimum water content. 11) The coefficient of permeability has a certain relations with density, gradation and void ratio and it increase with increasing of saturation degree.