• Economic and Environmental Geology
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• v.50 no.5
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• pp.353-361
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• 2017

Uranium concentration in groundwater of the Goesan area was anticipated high because the area contains Ogcheon metamorphic rock zone which partly includes coal bed bearing high uranium content and nearly half of the area is covered by granitic rocks. Groundwater samples collected from 250 wells in five 5 lithology (Ogcheon meta-sandy rock zone (Og1), Ogcheon lower phyllite zone (Og2), Ogcheon pebble bearing phyllite zone (Og3), Jurassic granite (Jgr), Cretaceous granite (Kgr)), of the area were analyzed and equivalent uranium concentrations (e(U)) from 200 rocks near sampled wells were measured using portable gamma spectrometry. Higher median value of e(U) (8.2 mg/kg) was found on Kgr outcrops. The median e(U) value of Og2 was not as high as that of Kgr and similar to those of Jgr, Og1, and Og3 (3.05~3.90 mg/kg). The uranium level in groundwater of the area ranged from 0.01 to $293.0{\mu}g/L$ with a median value of $0.87{\mu}g/L$ which is similar to the national median uranium level of $0.74{\mu}g/L$. The uranium concentration was high in the samples from the Kgr (median $4.74{\mu}g/L$) and low samples from the Og1, Og2, and Og3 (median $0.35{\sim}0.74{\mu}g/L$). The percentage of total samples having uranium level above $30{\mu}g/L$ was 2.8%, on the other hand, that of Kgr is 20.7%, reflecting additional survey on the Kgr area is needed.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.4
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• pp.52-64
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• 2010

This study was carried out to analyze the occurrence characteristics and the influence of forest environment factors on the debris flow of 3 national parks in korea. The results obtained from this study were summarized as follows; The total number of debris flow occurrence was 125 areas. The average length of the debris flow scar was 144m, average width was 20m. And the average area and sediment were $2,854m^2$ and $3,959m^3$ respectively. The factors influencing the debris flow were highly occurred in Metamorphic rock, mixed forest type. And also, slope gradient was $30{\sim}35^{\circ}$, aspect was NE, altitude was over 1,000m, vertical and cross slope was concave (凹), soil depth was below 15cm, stream order was 0 order. The variables of cross slope (complex), deciduous tree, soil depth (over 46cm), cross slope (concave), mixed forest type and altitude (801~1200m) in correlation analysis were significant at 1 % level. The landslide of high mountain area highly tend to change the debris flow in stream bed of torrent. The debris flow in national parks mainly occurred in high mountain area with long ridge and steep slope.

• The Journal of Engineering Geology
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• v.5 no.3
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• pp.249-258
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• 1995

The landslide occurred in the Nongong area of Dalseong - gun, Kyeongbuk, is described and analysed in terms of structural geology and clay mineralogy to understand the causes of the landslide. The result of the analyses shows that the slip direction and the scale of the landslide of the study area were controlled by the attitude of the major discontinuity planes m the area such as joints, faults and dikes. In addition, the surface of the slip planes of the landslide is composed of clay minerals, which are mostly tri - octahedral vermiculite and smectite. From this study it can be concluded that the presence of expandable clay minerals within the bedding joints and fracture zones in bed rock played an important role in causing the landslide of the study area.

• Advances in Energy Research
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• v.4 no.1
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• pp.87-106
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• 2016

In this research, optimum design of the combined solar collector, geothermal heat pump and thermal seasonal storage system for heating and cooling a sample greenhouse is studied. In order to optimize the system from technical point of view some new control strategies and functions resulting from important TRNSYS output diagrams are presented. Temperatures of ground, rock bed storage, outlet ground heat exchanger fluid and entering fluid to the evaporator specify our strategies. Optimal heat storage is done with maximum efficiency and minimum loss. Mean seasonal heating and cooling COPs of 4.92 and 7.14 are achieved in series mode as there is no need to start the heat pump sometimes. Furthermore, optimal parallel operation of the storage and the heat pump is studied by applying the same control strategies. Although the aforementioned system has higher mean seasonal heating and cooling COPs (4.96 and 7.18 respectively) and lower initial cost, it requires higher amounts of auxiliary energy either. Soil temperature around ground heat exchanger will also increase up to $1.5^{\circ}C$ after 2 years of operation as a result of seasonal storage. At the end, the optimum combined system is chosen by trade-off between technical and economic issues.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.9-16
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• 2005

The purpose of this study is to investigate the settlement characteristics of large drilled shafts embedded into bed rocks. To perform this research, 35 pile load test results for the large drilled shafts are used, because these deep foundations generally used as substructure systems for grand bridges. In case of the yield load can not be easily determined by load(P)-settlement(S) curve from the pile load test at the maximum loads, the standard settlements which can determine a yield load is established. The residual settlement equation of pile embedded in gneiss and igneous rocks is presented in this study. Also a equation is proposed to characterize the relationship between loads and elastic settlements in pile load tests on the large drilled shaft embedded into bedrock. Then, large drilled shaft's settlement characteristics are examined on pile length, pile diameter and pile's socked depth into rock at the pile tip.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1571-1580
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• 2008

Subsea tunnels that link land to island and among nations for transportation, efficient development of limited surface and pursuit of economic development should be designed to support pore water pressure on the lining. It is generally constructed in the bed rock of the sea bottom. When the tunnel excavation face meets fractured-zones below sea bottom, collapse may occur due to an increase of pore water pressure and large inflow. Such an example can be found in the Norwegian subsea tunnel experiences in 1980's. In this study hydraulic behavior of tunnel heading is investigated using numerical method based on the collapse of Norwegian subsea tunnel. The effect of pore water pressure and inflow rate were mainly concerned. Horse-shoe shaped model tunnel which has 50 m depth from the sea bottom is considered. To evaluate hydraulic performance, parametric study was carried out for varying relative permeability. It is revealed that pore water pressure has increased with an increase of sea depth. Especially, at the fractured-zone, pore water pressure on the lining has increased significantly. Inflow rate into tunnel has also increased correspondingly with an increase in sea depth. S-shaped characteristic relation between relative permeability and normalized pore water pressure was obtained.

• Geomechanics and Engineering
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• v.18 no.3
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• pp.267-275
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• 2019

Tabriz is a large Iranian city and the capital of the East Azerbaijan province. The bed rock of this city is mainly consisted of marl layers. Marl layers have some outcrops in the northern and eastern parts of city that mainly belong to the Baghmisheh formation. Based on their colors, these marls are classified into three types: yellow, green, and gray marls. The city is developing toward its eastern side wherein various civil projects are under construction including tunnels, underground excavation, and high-rise building. In this regard, the swelling behavior assessment of these marls is of critical importance. Also, in lightweight structures with foundation pressure less than swelling pressure, several problems such as walls cracking and jamming of door and windows may occur. In the present study, physical properties and swelling behavior of Baghmisheh marls are investigated. According to the X-ray diffractometer (XRD) results, the marls are mainly composed of Illite, Kaolinite, Montmorillonite, and Chloride minerals. Type and content of clay minerals and initial void ratio have a decisive role in swelling behavior of these marls. The swelling potential of these marls was investigated using one-dimensional odometer apparatus under stress level up to 10 kPa. The results showed that yellow marls have high swelling potential and expansibility compared to the other marls. In addition, green and gray marls showed intermediate and low swelling potential and swelling pressure, respectively.

• Journal of Korean Society of Forest Science
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• v.83 no.2
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• pp.175-190
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• 1994

In order to get fundamental information for prediction of landslide hazard, both forest and site factors affecting slope stability were investigated in many areas of active landslides. Twelve descriptors were identified and quantified to develop the prediction model by multivariate statistical analysis. The main results obtained could be summarized as follows : The main factors influencing a large scale of landslide were shown in order of precipitation, age group of forest trees, altitude, soil texture, slope gradient, position of slope, vegetation, stream order, vertical slope, bed rock, soil depth and aspect. According to partial correlation coefficient, it was shown in order of age group of forest trees, precipitation, soil texture, bed rock, slope gradient, position of slope, altitude, vertical slope, stream order, vegetation, soil depth and aspect. The main factors influencing a landslide occurrence were shown in order of age group of forest trees, altitude, soil texture, slope gradient, precipitation, vertical slope, stream order, bed rock and soil depth. Two prediction models were developed by magnitude and frequency of landslide. Particularly, a prediction method by magnitude of landslide was changed the score for the convenience of use. If the total store of the various factors mark over 9.1636, it is evaluated as a very dangerous area. The mean score of landslide and non-landslide group was 0.1977 and -0.1977, and variance was 0.1100 and 0.1250, respectively. The boundary value between the two groups related to slope stability was -0.02, and its predicted rate of discrimination was 73%. In the score range of the degree of landslide hazard based on the boundary value of discrimination, class A was 0.3132 over, class B was 0.3132 to -0.1050, class C was -0.1050 to -0.4196, class D was -0.4195 below. The rank of landslide hazard could be divided into classes A, B, C and D by the boundary value. In the number of slope, class A was 68, class B was 115, class C was 65, and class D was 52. The rate of landslide occurrence in class A and class B was shown at the hige prediction of 83%. Therefore, dangerous areas selected by the prediction method of landslide could be mapped for land-use planning and criterion of disaster district. And also, it could be applied to an administration index for disaster prevention.

• The Korean Journal of Ecology
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• v.16 no.4
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• pp.377-395
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• 1993

Habitat types, community structure and population characteristics of Koelreuteria paniculata were investigated in Mt. Wolak, Chungbuk and Naesokdong, Daegu, which are natural habitats of the species in inland region of Korea, and its origin was discussed. Habitats of Koelreuteria paniculata were classified to 3 types: sand bar formed by the sands flooded in the course of flow of the mountain stream (Type 1). crevice on the rock bed within the mountain stream (Type 2) and crevice of the rock around the edge of mountain stream (Type 3). Most Koelreuteria paniculata communities in Mt. Wolak site were composed of 3 layers of subtree layer, shrub layer and herb layer and that of Daegu site was 4 layers including tree layer. In the floristic composition of the Koelreuteria paniculata community, plants occurring frequently in the wet and open site, such as Zelkova serrata and Fraxinus rhynchoph-vlla showed high frequency. Frequency distribution of diameter at ground surface of Koelreutrria paniculata showed reversed J-shaped type. It was supposed that expansion of Koelreuteria paniculata community in Mt. Wolak site might be accomplished by the flow of the stream. Many saplings capable of becoming a successor of mature trees in Daegu site in near degenerating phase were established on the forest floor of the Koelreuteria paniculata community. From this result, it was supposed that these saplings originated from the seeds dispersed from a seed tree might form the Koelreuteria paniculata community of the next generation. On the other hand, the origin of Koelreutevia paniculata in inland sites was explained by two hypotheses: the one was that Koelreuteria paniculata might be transplanted by human and the other was that the present site might be native habitat of the community.

• Tunnel and Underground Space
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• v.27 no.4
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• pp.217-229
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• 2017

This study focuses on the improvement of the working environment in domestic collieries where temperature is increasing due to heat of the earth that is caused by the long-term mining. In order to improve the working environment of the mine, a ventilation evaluation was carried out for Hwasoon Mining Industry. In order to increase the ventilation efficiency of the mine, numerical analysis of the effect on temperature was carried out by using climsim, a temperature prediction program. The analysis shows that A coal mine needs $6,152m^3/min$ for in-flow ventilation rate but the total input air flowrate is $4,710m^3/min$, $1,442m^3/min$ of in-flow ventilation rate shortage. The 93 m hypothetical ventilation shaft from -395 ML to -488 ML could result about $3^{\circ}C$ temperature drop in the coal mine of -488 ML far. As a result of predicting the $CO_2$ concentration at -523 ML development using artificial neural network, the emission of $CO_2$ increased as the amount of coal and coal bed thickness increased. The factors that have the greatest effect on the amount of $CO_2$ emissions were coal layer thickness and coal mining. And, as the air quantity increases, it has a great effect on the decrease of carbon dioxide concentration.