• Explosives and Blasting
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• v.35 no.3
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• pp.31-54
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• 2017

In the countries operating nuclear reactors, the development of high-level radioactive waste(HLW) disposal technique is considered as an urgent and important issue for sustainable utilization of nuclear energy. In Korea, in which a low and intermediate radioactive waste repository is already operating, the construction of an underground research laboratory for in situ validation studies became a matter of interest with increasing concerns on the management of HLW. In order to construct and to operate an underground HLW repository safely in deep underground, the stability of rock mass should be guaranteed. As an important factor on rock stability, excavation damaged zone (EDZ) has been studied in many underground research laboratories in foreign countries. For accurate evaluation of the characteristics and effects of EDZ under disposal condition, it is required to use reliable investigation method based on the analysis of previous studies in similar conditions. In this study, status of foreign underground research laboratories in other countries, approaches for investigation the characteristics, size, and effect of EDZ, and major findings from the researches were surveyed and reported. This will help the accomplishment of domestic researches for developing HLW management techniques in underground research laboratory.

• Journal of Korea Water Resources Association
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• v.49 no.7
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• pp.579-588
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• 2016

Changes in precipitation due to climate change is made to induce the local and intensive rainfall, it is increasing damage caused by inland inundation. Therefore, it requires a technique for predicting damage caused by flooding. In this study, in order to determine whether this flood inundated by any route when the levee was destroyed, Which can simulate the path of the flood inundation model was developed for the SIMOD (Simplified Inundation MODel). Multi Direction Method (MDM) for differential distributing the adjacent cells by using the slope and Flat-Water Assumption (FWA)-If more than one level higher in the cell adjacent to the cell level is the lowest altitude that increases the water level is equal to the adjacent cells- were applied For the evaluation of the model by setting the flooding scenarios were estimated hourly range from the target area. SIMOD model can significantly reduce simulation time because they use a simple input data of topography (DEM) and inflow flood. Since it is possible to predict results within minutes, if you can only identify inflow flood through the runoff model or levee collapse model. Therefore, it could be used to establish an evacuation plan due to flooding, such as EAP (Emergency Action Plan).

• Analytical Science and Technology
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• v.16 no.5
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• pp.1041-1051
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• 2003

Neutron induced prompt gamma activation analysis (PGAA) offers a nondestructive, sensitive and relatively rapid method for the determination of trace and major elements and is proven to be convenient for online analysis of minerals, metals, coal, cement, petrochemical, coating, paper as well as many other materials and products. The technique has found many uses in medicine, industry, research, security and the detection of contraband items. This report reviews the present status and future trends of the PGAA techniques. Requirements for the system are neutron source, high resolution HPGe detectors with a high-voltage power supply, an amplifier, analog-to-digital converter, and a multichannel analyzer for the detection and measurement of prompt ${\gamma}$-ray emit form the neutron capture elements. Introducing a ${\gamma}$-${\gamma}$ coincidence system also improves the quality of the ${\gamma}$-ray spectrum by suppressing the background created from the Compton scattering of high energy prompt ${\gamma}$-rays. A PGAA system using a $^{252}Cf$ neutron source is currently under construction for the on-line measurement of several elements in aqueous samples at KAERI. The system can be applied for the detection of chemical weapons and explosives as well as various narcotics.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.6
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• pp.394-399
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• 2005

Near Infrared Spectroscopy (NIRS) has been used as a tool for the rapid, accurate and nondestructive assay of the fresh rice leaf in nitrogen content. NIRS used in this study was visible and near infrared spectroscopy type instrument, Foss model 6500. To obtain a useful calibration equation, standard regression between the data was analyzed by chemical analysis and by NIRS method. Accuracy of calibration equation for nitrogen content on fresh leaf of rice were 0.879, 0.858 and 0.819, respectively. Accuracy of calibration equation after outlier treatment increased as 0.017, 0.02 and 0.061 improved each with 0.896, 0.878 and 0.880, respectively. Calibration equation combined using merge function after accuracy of calibration equation more increased by 0.911. Difference analysis value between calibration equation and lab value by kjeldahl showed $0.001\%$. With this as same result is the possibility of closing the deterioration of the sample in order to omit a construction and pulverization process it is judged with the fact that the nitrogen content measurement of the fresh rice leaf which the possibility of reducing an hour and an expense is by a near infrared spectroscopy technique will be possible.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.15 no.4
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• pp.119-132
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• 2012

The unmanaged abandoned concrete roads are vulnerable toward the issues on soil and water pollution, which requires flexible managing method such as eco-corridor after the process of ecological restoration. Among various alternations of abandoned concrete-paved roads, ecological restoration technique may be the most suitable method in sites including high quality of natural environment. Therefore, as in Young dong province, GyungBu express highway (227.24~229.04km), which is near to Hwang-gan IC, the survey to measure its effect of soil under the paving and water pollution by abandoned concrete roads was discussed. Then, the restoration method of plantings of landscape trees and hydro-seeding methods of artificial soil media was appraised through consecutive monitoring. The soil adequacy analysis shows lower percentage of heavy metal substance in each depth level compared to standard limit stated by the Ministry of Environment, along with low concerns raised after the analysis on heavy metal content of the spilled water on the concrete roads. Meanwhile, Korean Weigela (Weigela subsessilis L.H. Baily) was found to be withered in small-scale landscape trees planting sites. Among the seeding plants. the family of leguminosae, Silene armeria, Dendranthema boreale, Caryopteris incana and Aster yomena show good establishment results. Overall studies on planting of small and large landscape trees, planting method of container plants, planting method of ground cover plants, and germination and development trend of seeding plants of the experimental restoration site on abandoned concrete roads are revealing specific trends in the way landscape woody plants establishment and growth. Finally, this study suggests further studies and survey on varied plant restoration methods on abandoned concrete-roads for developed design guidelines of their methods.

• Journal of Environmental Impact Assessment
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• v.24 no.2
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• pp.163-174
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• 2015

Urbanization caused various environmental problems like destruction of natural water cycle and increased urban flood. To solve these problems, LID(Low Impact Development) deserves attention. The main objective of LID is to restore the water circulation to the state before the development. In the previous studies about the LID, the runoff reduction effect is mainly discussed and the effects of each techniques of LID depending on rainfall types have not fully investigated. The objective of this research is to evaluate the effect of LID using the quantitative simulation of rainwater runoff as well as an amount of infiltration according to the rainfall and LID techniques. To evaluate the water circulation of LID on the development area, new land development areas of Hanam in South Korea is decided as the study site. In this research, hydrological model named STORM is used for the simulation of water balance associated with LID. Rainfall types are separated into two categories based on the rainfall intensity. And simulated LID techniques are green roof, permeable pavement and swale. Results of this research indicate that LID is effective on improvement of water balance in case of the low intensity rainfall event rather than the extreme event. The most effective LID technique is permeable pavement in case of the low intensity rainfall event and swale is effective in case of the high intensity rainfall event. The results of this study could be used as a reference when the spatial plan is made considering the water circulation.

• Journal of the Korean Geotechnical Society
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• v.28 no.8
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• pp.5-19
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• 2012

Vertical drains along with the preloading technique have been commonly used to enhance the consolidation rate of dredged placement formation. In practice, vertical drains are usually installed in the process of self-weight consolidation of a dredged soil deposit because this process takes considerable time to be completed, which makes conventional analytical or numerical models difficult to quantify the consolidation behavior. In this paper, we propose a governing partial differential equation and develop a numerical model for 2-D axisymmetric non-linear finite strain consolidation considering self-weight consolidation to predict the behavior of a vertical drain in the dredged placement foundation which is installed during the self-weight consolidation. In order to verify the developed model in this paper, results of the numerical analysis are compared with that of the lab-scaled self-weight consolidation test. In addition, the model verification has been carried out by comparing with the simplified method. The comparisons show that the developed model can properly simulate the consolidation of the dredged placement formation with the vertical drains installed during the self-weight consolidation. Finally, the effect of construction schedule of vertical drains and of pre-loading during the self-weight consolidation is examined by simulating an imaginary dredged material placement site with a thickness of 10 m and 20 m, respectively. This simulation infers the applicability of the proposed method in this research for designing a soil improvement in a soft dredged deposit when vertical drains and pre-loading are implemented before the self-weight consolidation ceases.

• Journal of the Korean GEO-environmental Society
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• v.7 no.6
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• pp.101-111
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• 2006

In case of drilled shafts installed by drilling through soft overburden onto a strong rock, the piles can be regarded as end-bearing elements and their working load is determined by the safe working stress on the pile shaft at the point of minimum cross-section or by code of practice requirements. Drilled shafts drilled down for some depth into weak or weathered rocks and terminated within these rocks act partly as friction and partly as end-bearing piles. The base resistance component can contribute significantly to the ultimate capacity of the pile. However, the shaft resistance is typically mobilized at considerably smaller pile movements than that of the base. In addition, the base response can be adversely affected by any debris that is left in the bottom of the socket. The reliability of base response therefore depends on the use of a construction and inspection technique which leaves the socket free of debris. This may be difficult and costly to achieve, particularly in deep sockets, which are often drilled under water or drilling slurry. As a consequence of these factors, shaft resistance generally dominates pile performance at working loads. The efforts to improve the prediction of drilled shaft pile performance are therefore primarily concerned with the complex mechanisms of shaft resistance development. In this study, the numerical analyses are carried out to investigate the behavior characteristics of side of rock socketed drilled shafts varying the loading condition at the pile head. The difference of behavior characteristics of side resistance is also evaluated with the effects of modelling of asperity.

• Journal of the Korean GEO-environmental Society
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• v.14 no.1
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• pp.43-51
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• 2013

Recently, engineering problems such as long-term settlement, differential settlement, and the resultant structural damage, have been frequently reported at construction sites. Use of Sand Compaction Piles(SCP) and Granular Compaction Piles(GCP) are good at remedying existing problems, improving bearing capacity and promoting consolidation. However, such compaction piles have the potential for clogging, which would limit their usability. Investigations into the potential for clogging in SCP, GCP, and GCP mixed with sand has not been thoroughly conducted and is the objective of this current study. Large scale direct shear tests were performed on sections of SCP, GCP, and sand mixed GCP to evaluate bearing capacity. Discrete Element Method analyses were conducted with PFC3D and Finite Element Analyses were conducted with MIDAS GTS to propose an algorithm to help reduce clogging in the granular compaction piles. Results from the large scale direct shear test and multiple simulations suggest a 70% gravel and 30% sand mixing ratio to be optimal for bearing capacity and reducing clogging.

• Journal of the Korean GEO-environmental Society
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• v.17 no.12
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• pp.27-34
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• 2016

Many steepened slopes have become increasingly advantageous because of the desire to increase land usage and decrease site development costs. The proven concept of tensile reinforcement allows construction of slopes with far steeper face angles than the soils natural angle. Steepened slope face reinforced with improved soil can increase land usage substantially while providing a natural appearance. The paper presents composite reinforced earth with improved soil surface and geogrid-reinforced backfill. For the stability of the steepened slope, the behavior of the composite reinforced earth are validated and verified by case study and numerical analysis. The case study has performed to investigate the deformation of reinforce soil slope for 14 months. Its horizontal behavior by general vertical load shows within the safe range (0.5% of structure height). As a result of numerical analysis and case study, the reinforcement effect of the steepened slope technique using improved soil is sufficient to be constructed as reinforced soil slope.