• Environmental Engineering Research
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• v.14 no.2
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• pp.120-125
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• 2009

Water stress has become a major concern in agriculture. Korea suffers from limited agricultural water supply, and wastewater reuse has been recommended as an alternative solution.A study was performed to examine the effects of microorganism concentration in the ponded-water of a paddy rice field with reclaimed-water irrigation for evaluating the microbial risk to farmers and neighborhoodchildren.Most epidemiological studies were performed based on an upland field, and they may not directly applicable to paddy fields. Beta-Poisson model was used to estimate the microbial risk of pathogen ingestion. Their risk value increased significantly high level after irrigation and precipitation.It implies that agricultural activities such as plowing, and fertilizing, and precipitation need be practiced a few days after irrigation considering health risks. The results about field application of the microbial risk assessment using E. coli showed difference according to monitoring time and treatment plot. Result of the microbial risk assessment showed that risk values of ground-water and reclaimed secondary waste water irrigation were lower than directly use of wastewater treatment plants' effluent. This paper should be viewed as a first step in the application of quantitative microbial risk assessment of E. coli to wastewater reuse in a paddy rice farming.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.11a
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• pp.275-279
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• 2004

This study was done to detect the topographic and terrain change of the vicinity of the west coast. To make the basic map of the change in topology and terrain, the mosaic images were made using the images from the satellite, which were given the geometric correction based on the GCP (Ground Control Point) and DEM (Digital Elenation Model) data. The accuracy of the images was examined by .empaling them with CCP through 1:25,000's digital map. After that, among the resultant images of the 1970s and 2000s, those of Sihwa, Hwaong and Ansan, the lands reclaimed by drainage were compared to observe the change in the area. From this study, the accuracy of the images of the west coast from satellite could be acquired and the change of the topology and terrain was detected effectively. From the results, it was known that, in case of the land the topological change was not so big due to the development in the reclaimed land or the bare land. In Sihwa, the size of the land was increased 180 $\textrm{km}^2$ and that of the seashore was decreased 110 km. in Hwaong the size was increased 50 $\textrm{km}^2$ and in Ansan the city space was increased 71 $\textrm{km}^2$ due to the formation of the industrial complex.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1071-1076
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• 2004

The purpose. in this study. is to analyze liquefaction potential of Inchon International Airport at the Area Phase ' I ' for Railway Construction of all, seismic response was analyzed using the computer program, Shake91. Four methods proposed by Seed & Idriss. Eurocode, Iwasaki & Tatsuoka. and Ishihara were used for assessment of liquefaction potential and safety factors calculated form these methods are compared. Based on the results of seismic response analysis, the maximum acceleration at the ground surface is larger than that evaluated site factor effect by using site factor because these areas are composed of very loose sand clay. Especially, in the case of analysis with long period earthquake data. it is appeared that the acceleration of earthquake is amplified more largely. Therefore, accurate seismic response analysis is suggested for the design on the important structures on reclaimed land. The analytical results of liquefaction potential show that the increments of N-value and effective overburden pressure with remediation make safety factors increase. Through comparing the safety factors evaluated from four method, the safety factor calculated by See & Idriss method in the lowest one and it is found that the SPT N-value effect the safety factor very largely. And, Iwasaki & Tatsuoka method is affected by various factors such as average grain size. fine contents, confining pressure. In conclusion. to minimize earthquake Risk by liquefaction, the efficient remediation is essential and seismic response analysis should be carride out.

• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.3
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• pp.27-33
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• 2021

Reclaimed land was mainly used as agricultural land for rice production. As a higher value-added business in the agriculture has recently been activated, green houses are being constructed. In case of green house construction on the reclaimed land, it is generally soft ground with high soil water content, so it is important to design the foundation for greenhouse construction. The object of this study, a pull-out test was conducted to derive the base line data of the wooden pile foundation when constructing a green house. To reproduce the actual site, 30% of soil saturation and 70% of soil saturation were created in the soil box. Groove number and depth were set as design factors of the wooden pile, and a pull-out test was conducted. As a result of the test, pull resistance increased as the number of grooves increased, pull-out resistance according to groove depth was different according to soil saturation. Also, after the experiment, we want to compare the set-up effects over time.

• Journal of the Korean Geotechnical Society
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• v.21 no.3
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• pp.43-54
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• 2005

The ground movements during three. full-scale trial diaphragm wall (DW) panel constructions were monitored and analysed. The DW panels were constructed in reclaimed fill where sedimentary marine deposit and residual weathered soils are being consolidated. The monitoring data showed exceptionally large lateral ground movements of up to 293 mm near a trench due to the DW panel constructions, which is about 0.8$\%$ D, where D is the maximum excavation depth. It was observed that deliberate holding period of the trench resulted in a significant increase in the lateral ground movements of about 50-225$\%$. A pre-treatment of the marine deposit by installing a single line of jet grout columns around the trench prior to the excavation was found to be a very effective way of reducing the ground movements. The measured ground settlements were compared with some relevant case histories. DW panel constructions in sedimentary marine deposit are likely to cause maximum ground surface settlement up to 0.225$\%$ D.

• Korean Journal of Remote Sensing
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• v.30 no.2
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• pp.161-172
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• 2014

Established in the lower reaches of the Nakdong river in Busan, the Noksan national industrial complex is one of the deepest soft ground areas in Korea. In case of the costal landfill having deep soft ground, there is a significant residual settlement over a long period of time. In this study, there was observed ground subsidence occurred in the Noksan national industrial complex from September 2002 to April 2007 by applying DInSAR and SBAS time series method using RADARSAT-1 and Envisat SAR datasets. As a result, it was calculated that ground subsidence developed at the velocity of about maximum 10 cm/yr and mean 6 cm/yr at the eastern center, west, western center and southern area contiguous on the coastline of the study area during the period from September 2002 to April 2007. In addition, the RADARSAT-1 average displacement map has been compared with the total displacement map observed by accurate magnetic probe extensometer during the period from 2001 to 2002. Since the time series displacement has shown a linear trend mostly, we consider that continuous monitoring should be needed until the ground subsidence of the study area has been stabilized.

• Journal of the Korean GEO-environmental Society
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• v.11 no.10
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• pp.5-13
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• 2010

Low slump mortar grouting is widely used in reinforcement of structural foundation and ground improvement in soft ground, and has advantage which construction is possible in insufficient space. However it has been not yet studied sufficiently to estimate the effect of ground improvement in design step and to prove the estimating method. So the method must be developed in order to use the low slump mortar grouting method in various cases. In this study, the field tests were performed in the reclaimed soils to measure the effect of ground improvement. Then it was compared with what was calculated by the existing formula that was formerly suggested. The results show that the value from the formula was similar with the value from the field tests. Also it was proved that the formula was available to estimate the effect of ground improvement in the loose granular soils.

• Journal of the Korean Geotechnical Society
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• v.37 no.7
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• pp.25-34
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• 2021

Since the dredging reclaimed land consisting of soft ground is very weak in support, the difficult and complex factors should be considered in the design to calculate accurate bearing capacity of soft ground. Recently, various reinforcement construction methods of soft ground have been designed for dredged landfills, but the stabilities are predicted by calculating conventional Meyerhof (1974) equation for trafficability in soft ground. Conventional equations increase economic costs by underestimating bearing capacity of weak ground in order to ensure constructive safety, so a modified equation has been proposed from the literature. The paper attempts to experiment and compute important factors, such as stitching fiber and seam tensile strength of geotextiles, that are not theoretically considered and can be identified in the field. In addition, The evaluation of the bearing capacity of the modified equation is verified to be stable for trafficability through the plate bearing test performed on site.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.55-64
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• 2002

In the present study, in order to apply a cyclic viscoelastic-viscoplastic constitutive model to multi-layered ground conditions during large earthquake, the numerical simulations of the 1995 Hyogoken Nanbu Earthquake at Port Island, Kobe, Japan, were performed by the seismic response analysis. From the seismic response analysis, it was found that the acceleration calculated from the cyclic elasto-viscoplastic model and cyclic viscoelastic-viscoplastic models for clay was in close agreement with the recorded accelerations at the Port Island down-hole array, and the cyclic elastic-viscoplastic and viscoelastic-viscoplastic constitutive models showed little different behavior characteristics near clay layer. Thus, the propriety of viscoplastic model for clay was convinced. Therefore, it can be concluded that a cyclic viscoelastic-viscoplastic constitutive model can give a good description of the amplification and also it showed accurate damping characteristics of clay during large event which induces plastic deformation in large strain range.

• Journal of the Korean GEO-environmental Society
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• v.12 no.6
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• pp.25-34
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• 2011

Dredged and reclaimed ground in progress at the West Coast has a high content of coarse particles. There will be different behaviors depending on the location of outlet and engineering properties of soil when its ground is dredged by a pump. Therefore, the experiments were conducted that were manufactured about the chamber equipment of length 2,650mm, width 770mm, height 735mm, experimented step filling method and water content about 300%, 500% and 700% respectively with SM and ML samples in order to realize segregating sediment characteristics of dredged ground with changing much fine. With results of analysis, ML sample by higher initial water content was reached to the period of complete sedimentation and coefficient of sedimentation consolidation increased with increases of diffusion distance. SM samples showed behavior of coarse soil with diffusion distance 120cm, diffusion distance of more than 120cm showed a similar tendency with ML sample under the influence of fines. In ML sample, it could be also found that lower depth and the more increasing diffusion distance increase in percentage of sieve #200 but water content decreases. In SM sample, it could be also found that coarse soil was piled at near the diffusion distance zone but fine soil was piled at the far diffusion distance zone and prominent difference showed between percentage of sieve #200 and water content(%) by boundary point 120cm~160cm of both samples. Also, shear strength was expressed ML-maximum 2.97kPa, SM-maximum 10.2kPa with diffusion distance.