• Journal of the Korean Society of Groundwater Environment
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• v.7 no.1
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• pp.55-58
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• 2000

Methyl tertiary butyl ether (MTBE) is a gasoline additive that boosts the oxygen content in fuel (an oxygenate), resulting in less air-polluting carbon monoxide being released from vehicle exhaust systems. Then, groundwater contamination problems have been developed in areas where the chemical is used. Common sources of water contamination by MTBE include leaking underground gasoline storage tanks and leaks and spills from above ground fuel storage tanks, etc.. Studies on the chemical and these problems are going on abroad vigorously. These studies should be performed in our country as well more actively. This paper reviews on articles on these studies and focuses on the identification of the chemical as a groundwater contamination source.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.4
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• pp.475-481
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• 1996

This study was carried out to acquire the basic information of root growth under different pot size, imposing different space limitation on rhizosphere. Different size of pots that had same surface area but different depth, 5cm(Iength)$\times$5cm(width)$\times$30, 15, 5cm(depth), were used during the seedling stage of tobacco plant. Space limitation on rhizosphere affected not only the aerial growth, stem height, leaf area and shoot dry weight, but also root growth and root architecture. Aerial growth was highly related to growth of underground part, so space limitation on rhizosphere decreased aerial growth. Limitation on pot volume by reducing pot depth induced new rooting on crown. Root number and relative multiplication rate were higher in small pot that had 5cm depth than large pot, but total root length and mean extension rate showed reverse patterns. Root numbers of 1st order and 2nd order were increased as pot depth was increased, but the root number of 3rd order was increased in small pot. Root system of seedling grown in large pot distributed more horizontally than that in small pot at 20 days after temporary planting (DAT), but the root architecture of seedling was reversed at 25 DAT.

• Journal of the Korean Geotechnical Society
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• v.30 no.6
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• pp.5-21
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• 2014

It has been pointed out that the collapses of unsaturated road embankments caused by earthquake are attributed to high water content caused by the seepage of the underground water and/or the rainfall infiltration. Hence, it is important to study influences of water content on the dynamic stability and deformation mode of unsaturated road embankments for development of a proper design scheme including an effective reinforcement to prevent severe damage. This study demonstrates dynamic centrifugal model tests with different water contents to investigate the effect of water content on deformation and failure behaviors of unsaturated road embankments. Based on the measurement of displacement, the pore water pressure and the acceleration during dynamic loading, dynamic behavior of the unsaturated road embankments with about optimum water content and the higher water content than the optimum one have been examined. In addition, an image analysis has revealed the displacement field and the distributions of strains in the road embankment, by which deformation mode of the road embankment with higher water content has been clarified. It has been confirmed that in the case of higher water content the settlement of the crown is large mainly owing to the volume compression underneath the crown, while the small confining pressure at the toe and near the slope surface induces large shear deformation with volume expansion.

• Fire Science and Engineering
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• v.15 no.1
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• pp.127-138
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• 2001

I. introduction. A government goal at the present is established to make a welfare nation and to keep people's safe living, but it is criticised that when a large-scale disaster happens, the authority concerned could not deal with it, causing many people injured and material damage. Moreover, in these days, cities have many risk factors. extremely large and intelligent building, industrial facilities and underground equipment have many risk themselves along with scientific progress. The cope with disaster effectively, government must have efficient organization, skillful personnel, tool, facilities and so on. To reduce the damages, what's the most effective government organization\ulcorner II. Government organization for managing disaster In a few decades, a large-sized accidents broke out in korea, for example, collapse of Sampoong department store, break of Sungso bridge, explosion of Daegu city gas, gas explosion accident at Ahyon-dong etc. but government has not any adequate disaster response organization. Especially, after collapse of Sampoong department store broke out, Disaster Management Act is enacted to solve the past problem. According to Disaster management Act, disaster is limited in manmaid disaster. Therefore, in this thesis, disaster management is inspected theoretically, organization of disaster management for pattern of disaster, and role, duty of government organization, emergency relief organization system and actual conditions are analyzed. there are some problems. there are trials and errors. the government has changed the disaster management organization by the disaster management law. the organization consists of central and local government. but both of government do not work together harmoniously. in thesis, I would like to introduce the advanced nations disaster management organization, and study our central, local government organization. III. Conclusion Change and development of the government disaster management organization is the goal of this thesis. we have to increase public service in response and manage disaster. protecting civilian's life from the disaster is very important responsibility of government. there would be better way of government disaster management organization.

• Journal of Korea Soil Environment Society
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• v.1 no.1
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• pp.89-102
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• 1996

An integrated model is presented to describe underground flow and mass transport, using a multicomponent multiphase approach. The comprehensive governing equation is derived considering mass and force balances of chemical species over four phases(water, oil, air, and soil) in a schematic elementary volume. Compact and systemati notations of relevant variables and equations are introduced to facilitate the inclusion of complex migration and transformation processes, and variable spatial dimensions. The resulting nonlinear system is solved by a multidimensional finite element code. The developed code with dynamic array allocation, is sufficiently flexible to work across a wide spectrum of computers, including an IBM ES 9000/900 vector facility, SP2 cluster machine, Unix workstations and PCs, for one-, two and three-dimensional problems. To reduce the computation time and storage requirements, the system equations are decoupled and solved using a banded global matrix solver, with the vector and parallel processing on the IBM 9000. To avoide the numerical oscillations of the nonlinear problems in the case of convective dominant transport, the techniques of upstream weighting, mass lumping, and elementary-wise parameter evaluation are applied. The instability and convergence criteria of the nonlinear problems are studied for the one-dimensional analogue of FEM and FDM. Modeling capacity is presented in the simulation of three dimensional composite multiphase TCE migration. Comprehesive simulation feature of the code is presented in a companion paper of this issue for the specific groundwater or flow and contamination problems.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.3
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• pp.395-406
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• 2016

Population and development are concentrated by urbanization. Consequently, the usage of underground area and the riverside area have been increased. By increasing impermeable layer, the urban basin drainage is depending on level of sewer. Flood damage is occurred by shortage of sewer capacity and poor interior drainage at river stage. Many of researches about flood stress the unavailability of connection at the river stage with the internal inundation organically. In this study, flood calculated considering rainfall and combined inland-river. Also, using urban runoff model analyze the overflow of sewer. By using results of SWMM model, using flood inundation analysis model analyzed internal drainage efficiency of drainage system. Applying SWMM model, which results to flood inundation analysis model, analyzes internal drainage efficiency of drainage system under localized heavy rain in a basin of the city. The results of SWMM model show the smoothness of internal drainage can be impossible to achieve because of the influence of the river level and sewer overflow appearing. The main manholes were selected as the manhole of a lot of overflow volume. Overflow reduction scenarios were selected for expansion of sewer conduit and instruction retention pond. Overflow volume reduces to 45% and 33~64% by retention pond instruction and sewer conduit expansion. In addition, the results of simulating of flood inundation analysis model show the flood occurrence by road runoff moving along the road slope. Flooded area reduces to 19.6%, 60.5% in sewer conduit expansion scenarios.

• Journal of Bio-Environment Control
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• v.7 no.1
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• pp.25-33
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• 1998

Root zone temperature have influenced on protected cultivation in winter season. Especially root zone temperature is acted on limiting factor in crop cultivation. This study was conducted to obtain optimum temperature of root zone in Protected cultivation Root zone was warmed by heated water($28^{\circ}C$) flowing through the PPC pipe(${\phi}15$) buried depth 40 cm. And the flowing water was heated by solar system. Minimum air temperature during night time was set at $14^{\circ}C$ and maximum air temperature during day time was set at $28~30^{\circ}C$ the growing period of cucumber was from Nov. 6, 1996 to Jan. 30, 1997. The results are summarized as follows. 1. Average soil temperature at 15~20 cm depth was $22^{\circ}C$ at warming plots, $17~18^{\circ}C$ at non-warming plots 2. Early growth in leaf length, stem diameter, number of leaves and leaf area for 30 days after planting were accelerated by root zone warming. Especially, the grawing rate of soil warming plots was higher 27% in leaf length, 51% in leaf number, 150% in leaf area than non-warming Plots. Above-ground and underground part of warming plots was higher 117%, 56% than non-warming plots. 3. In total yield analysis, number of fruits were 614 in soil warming and 313 in non-warming plots. In the result, total yield of soil warming plots was increased with 196% than non-warming plots. 3. In total yield analysis. number of fruits were 614 in soil warming and 313 in non-warming plots. In the result. total yield of soil warming plots was increased with 196% than non-warming plots.

• Journal of the Korea Institute of Building Construction
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• v.9 no.6
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• pp.161-168
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• 2009

In an architectural construction, underground construction is a critical path forming a major part of the total construction period and cost, and particularly in big cities, its size has been increasing every year. A basement wall currently constructed in the field needs a large functional work force, and the construction is under progress by the Euroform and Soldier system, which is disadvantageous in terms of the construction period. Therefore, in this research, non-supporting forms which are applicable to the buildings construction were developed, based on the non-supporting forms partly used in some civil engineering works. In addition, the size of a form was assumed and its economical efficiency was compared to that of the Euroform and Soldier system which is used most in construction fields, and the results were analyzed. The study results showed that the construction cost of composite non-supporting forms was higher than that of the Euroform and Soldier system by about 8%, and the construction cost of non-composite non-supporting forms were lower than that of the Euroform and Soldier system by about 9%. However, in the case of composite non-supporting forms, the amount of concrete and reinforcing rods remarkably decreased in structural construction, so it has the effect of an economical cost reduction compared to the construction cost of existing walls by about 35%

• Tunnel and Underground Space
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• v.19 no.5
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• pp.432-439
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• 2009

For more reliable estimation of seismic source, attenuation properties and dynamic ground property, site amplification function should be considered. Among various estimation methods, this study used the Nakamura's method (1989) for estimating site amplification characteristics. This method was originally applied to the surface waves of background noise and therefore there are some limitations in applying to general wave energy. However, recently this method has been extended and applied to the S wave energy successfully. This study applied the method to S wave and Coda wave energy, which is equivalent to the backscattered S wave energy. We used more than 60 observed ground motions from 5 earthquakes which were occurred recently, with magnitude range from 3.6 to 5.1. Each station showed characteristic site amplification property in low-, high- and resonance frequencies. Some of the stations showed as high as 4 times of site amplification in the range of specific frequencies, which may imply abnormal small scale geologic strata below the station or development of various trapped modes in the basin structure. Moreover, removal of site amplification can give us more reliable seismic source and attenuation parameters, addition to the seismic hazard estimation.

• Tunnel and Underground Space
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• v.23 no.6
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• pp.480-492
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• 2013

After the introduction of geothermal power generation technology based on engineering reservoir creation that can be applied on non-volcanic region, industrial need for studies on the efficient and economic execution of costly deep-depth drilling work becomes manifest increasingly. However, since it is very difficult to predict duration and cost of boring work with acceptable reliability because of many uncertain events during the execution, efficient and organized work management for drilling is not easily achievable. Especially, the round trip that discretely occurs because of the abrasion of bit takes more time as the depth goes deeper and it has a great impact on the work performance. Therefore, a technology that can simulate the occurrence timing and depth of round trip in advance and therefore optimize them is essentially required. This study divided the abrasion state of bit into eight steps for simulation cases and developed a forecast algorithm, i.e., TOSA which can analyze the depth and timing of round trip occurrence. A methodology that can divide a unit section for simulation has been suggested; while the Bourgoyne and Young model has been used for the forecast of drilling rates and bit abrasion extent by section. Lastly, the designed algorithm has been systemized for the convenience of the user.