• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.795-798
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• 2003

Toxic organics are of great environmental concern primarily because they are toxic to mammals and birds, and are relatively soluble in water to contaminate surface water and groundwater. In this study, the decomposition of phenol, a widely used organic, in aqueous solutions by Boron doped diamond(BDD) electrode was examined. Thin, Boron-doped conducting diamond films are expected to be excellent electrodes for industrial electrolysis. Boron-doped diamond (BDD) were used as anode for generating ozone gas by electrolysis of acid solution. In this work. we have studied ozone generating system using BDD electrode. In order to determine the ozone generation properties of diamond electrode, experimental conditions, electrolyte concentration, temperature, flow rate and reaction time were varied diversely. As a result, we could confirm that ozone gas was generated successfully and the performance of diamond electrode was stable for electrolyte while $PbO_2$ electrode was disintegrated. Actually we are found that ozone amount increased by lowering the temperature of electrolyte. Decomposition of phenol concentration in the reaction solution by photolytic ozonation( $UV/O_3$) was analyzed by HPLC epuipped with a UV detector.

• Proceedings of the Korean Environmental Health Society Conference
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• 2002.04a
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• pp.91-99
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• 2002

A recent survey investigated that there were over one thousand un-controlled closed landfills(1,072 sites) in Republic of Korea. Most of these landfills were constructed before 1986. Waste management act were not promulgated at that time, so they usually do not have dranage system and leachate treatment facility. Also, considerable attention has been received to landfill leachate pollution, leachate has an adverse impact on the surrounding environment such as soil, groundwater, and water supply source. According to the result of survey for closed landfill management, it was reported that 875 sites out of 1,072sites(81.6％) have no leachate treatment facility and 630 sites out of 1,072sites(58.7％) have been used for farm lands and residence. Consequently it is hard to do postclosure care continuously in most of cases and these uncontrolled landfills have contaminated farm lands and residence. The average age of these landfills are ranged mostly between 2 to 15 years. Much time and advanced technology are needed to remediate these uncontrolled landfills, therefore the survey for present status of closed landfill sites is required and suitable treatment processes should be prepared. With this point of view, We has been investigated to find out the present status of closed landfill, problems of post management and discussed plans for remediation and reuse. Remedial actions of un-controlled landfill have been carried out the many cities since 1997 upto now. Most frequently applied technology were reuse after excavation and there were several cases to capping in the surface of landfill and to construct subsurface barriers. It is considered that landfills in use have a possibility not to be controlled because of inadequate construction and improper management. Therefore remediation of uncontrolled landfills and recovery technology should be develop continuously Especially, it has been expected that resource technology of landfill gas as a energy has some advantages in controlling odors in the site area and accelerating stabilization of landfills with the energy.

• Journal of Environmental Impact Assessment
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• v.13 no.6
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• pp.295-305
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• 2004

After the Rio declaration on environment and development in 1992, developed countries are undertaking "environmentally sustainable transportation (EST)" projects. To meet the needs for EST, current transportation policies in Korea are rapidly reforming and one of its concerns is modernizing and upgrading railway freight system. Planning new railroad construction projects is increasing and subsequent environmental impact assessment (EIA) demands improvements, especially in both the EIA and decision making systems. In this paper, we discuss the present status of EIA for railroad construction projects, especially, by analyzing the EIA documents for the last six years. The EIA for railroad construction projects accounts for only 4.9% of total 918 project EIAs during 1998-2003, and the portion is gradually increasing. Major environmental concerns for EIA in railroad construction projects were geomorphological and ecological changes, protection of rare organisms, air pollution, water pollution, waste management, and noise, etc. We compared characteristics of environmental impacts of railroad construction with those of vehicle road construction, based on environmental and construction-planning indicators appeared in Environmental Impact Statements. Railroad construction usually requires longer tunnels and bridges for a given length than those for vehicle road construction. In addition, the amounts of geomorphological and ecological changes (road-cutting, embankment, devegetation, etc.) in railroad construction were generally less than 50% of those in vehicle road construction. To develop environmentally friendly railway systems, monitoring studies for environmental impacts of railroads such as habitat fragmentation and road kills, dispersal of alien plants, tunnelling effects on groundwater and vegetation, and noise impacts are highly recommended.

• Journal of Korea Soil Environment Society
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• v.1 no.1
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• pp.103-109
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• 1996

The cover liners at municipal and hazardous waste landfill is not emphasized as much as the bottom liners. However, one of the most effective reason of landfill destroy is the cover liner failure. The cover system at municipal and hazardous waste landfill, 1 perform the following functions, at minimum: promote surface runoff, impede infiltration, protect settlement in the landfill, and provide a buffer from surface exposure of the waste. This research was to expand the existing knowledge base of landfill cover liner behavior during period of freeze/thaw Also, the great Lysimeter was built in the laboratory to provide as much as same condition with the field and three designs were simulated by actual cover materials. The result of simulation indicated the clay was effected by freezing/thawing. The degradation of cover liners in the frost penetration affects the physical, engineering properties of clay. these factors may consider to design and construct of the landfill. This paper provides the description of testing cover liners, experimental results and a discussion of the results of the simulation.

• Geomechanics and Engineering
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• v.22 no.4
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• pp.291-303
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• 2020

The deformation of the rock surrounding a tunnel manifests due to the stress redistribution within the surrounding rock. By observing the deformation of the surrounding rock, we can not only determine the stability of the surrounding rock and supporting structure but also predict the future state of the surrounding rock. In this paper, we used grey system theory to analyse the factors that affect the deformation of the rock surrounding a tunnel. The results show that the 5 main influencing factors are longitudinal wave velocity, tunnel burial depth, groundwater development, surrounding rock support type and construction management level. Furthermore, we used seismic prospecting data, preliminary survey data and excavated section monitoring data to establish a neural network learning model to predict the total amount of deformation of the surrounding rock during tunnel collapse. Subsequently, the probability of a change in deformation in each predicted section was obtained by using a Bayesian method for detecting change points. Finally, through an analysis of the distribution of the change probability and a comparison with the actual situation, we deduced the survey mark at which collapse would most likely occur. Surface collapse suddenly occurred when the tunnel was excavated to this predicted distance. This work further proved that the Bayesian method can accurately detect change points for risk evaluation, enhancing the accuracy of tunnel collapse forecasting. This research provides a reference and a guide for future research on the probability analysis of tunnel collapse.

• Journal of Korea Water Resources Association
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• v.34 no.5
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• pp.449-458
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• 2001

In order to verify the numerical model, which was developed to simulate the behavior of the two-phase fluid flow in a single fracture, the characteristic equation of relative permeability was incorporated into the developed numerical model, and the computed results were compared with the experimental results of the model test. As results of the sensitivity analysis on the roughness and the aperture size of fracture, the gas velocity was inversely proportional to the fracture roughness, and not proportional to the square of aperture size which is usually observed in single phase flow in a single fracture. The numerical model was applied to the underground LPG storage terminal in order to check the field applicability. The simultaneous flow of water and gas in accordance with the operation pressures in a single fracture near cavern was simulated by the model. It was shown that the leaked gas was able to be controlled in a single fracture neither by the pressure of operation nor by that of groundwater in case the fracture became smoother in roughness and smaller in aperture size.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.6 no.4
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• pp.257-263
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• 2008

We analyzed the statistical properties for the conductive background fractures in the Low and Intermediate Level Waste(LILW) disposal site to conceptualize of its groundwater flow system. The background fractures were classified to fracture sets based on their trends and plunges that were obtained from the borehole logging data, and then the fracture transmissivity distribution was inferred from the fixed interval hydraulic test results. The fracture size distribution of each fracture set was estimated using the fracture density and fracture mapping data. To verify the analyzed results, we compared observed field data to simulated one from the DFN model that was constructed with the analyzed statistical properties of the background fractures, and they showed a good agreement.

• Economic and Environmental Geology
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• v.34 no.6
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• pp.595-600
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• 2001

Recently, interests in subsidence hazard have been increased due to the underground construction such as subway construction and managements of abandoned mines. GIS analysis of subsidence hazard has a lot of advantages in handling of spatial data and managing database. For better result of GIS analysis, there are some necessities of modifying previous subsidence theory and model. To take surface profile into account allows the application of complicated topology. Furthermore. for 3-dimensional analysis. two subsidence profile curves that are perpendicular to each other should be considered simultaneously. Through these modifications, the model for subsidence analysis using GIS can be established. With ideal case of cavities and other conditions, GIS analysis was accomplished and meaningful results were produced. More realistic properties of cavity. soil layers, groundwater condition and topology will enable GIS analysis method to produce more reliable result and to widen the area of applications.

• Economic and Environmental Geology
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• v.11 no.3
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• pp.99-108
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• 1978

The Gum-Ho river basin is one of the densely populated area having more than 35% of the total population and it was also well irrigated since earlier days in the Nackdong river basin. Most of the easily developed source of surface water are fully utilized, and at this moment the basin is at the stage that no more :surface water can be made available under the present rapid development of economic condition. Since surface water supplies from the basin have become more difficult to obtain, the ground water resources must be thoroughly investigated and utilized greatly hereafter. In economic ground of the basin what part could ground water play? In what quantities and, for what uses could it be put? The answer to these questions can be relatively simple;the ground water resources in the basin can be put at almost any desired use and almost anywhere in the basin The area of the basin is at about $2088km^2$ in the middle part of Nackdong river basin and it is located along the Seoul-Pusan express highway. The mean annual rainfall is about 974.7mm, most of which falls from June to September during the monsoon. Accumulated is appeared approximately after every 8 year's accumlated dry period with the duration of 5 years. The water bearing formation in the basin include unconsolidated alluvial deposits in Age of Quaternary, saprolite derived from weathered crystalline rocks, Gyongsang sedimentary formations of the period from late Jurassic to Cretaceouse, and igneouse rocks ranging of the Age from Mesozoic to Cenozoic. The most productive ground water reservoir in the basin is calcareous shale and sandstones of Gyongsang system, which occupies about 66% of the total area. The results of aquifer test on Gyongsang sedimentary formation show that average pumping capacity of a well drilled into the formation with drilling diameter and average depth of $8{\frac{1}{2}}$ inch and 136m is $738m^3/day$ and also average specific capacity of those well is estimated $77.8m^3/D/M$. Total amount of the ground water reserved in the basin is approximately estimated at 37 billion metric tons, being equivalent 18 years total precipitations, among which 7 billion metric tons of portable ground water can be easily utilized in depth of 200 meters.

• Analytical Science and Technology
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• v.23 no.6
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• pp.560-565
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• 2010

Perchlorate ion ($ClO_4^-$) has been widely used as oxidizing agent in military weapon system such as rocket and missile fuel propellant. So it has been challenging to remove the pollutant of perchlorate ion. nanoscale zero valence iron (nZVI) particles are widely employing reduction catalyst for decomposition of perchlorate ion. nZVI particles has increasingly been utilized in groundwater purification and waste water treatment. But it have strong tendency of aggregation, rapid sedimentation and limited mobility. In this study, we focused on reduction of perchlorate ion using nZVI particles immobilized in alginate polymer bead for stabilization. The stabilized nZVI particles displayed much greater surface area, and much faster reaction rates of reduction of perchlorate ion. In this study, an efficient way to immobilize nZVI particles in a support material, alginate bead, was developed by using $Ca^{2+}$ as the cross-linking cations. The efficiency and reusability of the immobilized Fe-alginate beads on the reduction of perchlorate was tested at various temperature conditions.