• Journal of Ecology and Environment
• /
• v.43 no.3
• /
• pp.297-304
• /
• 2019

Background: The growing wild boar population has become a social issue and its feeding characteristics could affect the physical condition and the plant species composition in the South Korean forests. We aimed to reveal the preference of the wild boar on forest type and site condition as feeding grounds in two cool-temperate forested national parks, Odaesan and Seoraksan, in order to provide information to manage the growing population. Results: The 75 plots (53.6%) out of 140 plots were used as feeding grounds by the wild boar, implying a considerably large population. Especially, the observation frequency as feeding ground was the highest in Quercus forests (73.3%), and it was significantly more preferred than deciduous forest type (44.2%) and coniferous forest type (32.4%) (${\chi}^2=17.591$, p < 0.001). Significantly more and deeper pits were found in Quercus forests. Moreover, high elevation and gentle slope ridge were relatively preferred regardless of forest distribution. Conclusions: South Korean forests are growing qualitatively and quantitatively. Particularly, Quercus forest area has increased markedly, while coniferous forest area has decreased. Since the Quercus forest provides rich food sources for the wild boar, the enlargement of this forest type is expected to increase the wild boar population. The forests located at high elevations have high species diversity, and it is expected that these forests will be greatly affected by the increase in the wild boar population as preferred feeding grounds.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.24 no.1
• /
• pp.111-119
• /
• 2021

This study was conducted to investigate the growth characteristics of artificially planted trees on top of the underground parking lots. The trees were planted 17 years ago and are now in good condition. The survey results are as follows. The planting depth of the trees was 0.9 - 1.3m. The horizontal roots of the trees were distributed in the depth of 0.2m ~ 0.6m, Growth condition was also considered to be good. Also, in the case of the straight root of the trees, the pine tree(Pinus densiflora) grew near the bottom but tree root was very thin, and the Japanese hackberry tree(Celtis sinensis) and the zelkova tree(Zelkova serrata) were seemed to bend at the bottom and to grow by changing direction. When trees were planted on artificial ground, the roots grew well horizontally, and the forces of growing vertically were much weakened. because the plants were planted in earth ball state. As a result, it was considered that the roots would hardly penetrate the bottom-pressing concrete floor.

• Journal of Korean Society of Water and Wastewater
• /
• v.31 no.1
• /
• pp.21-28
• /
• 2017

This study was performed to propose the sewer defect scoring, and grading protocols for sewer condition assessment. For this, sewer defect scoring methods were comparatively analyzed and reviewed for four international condition assessment protocols, which are established based on WRc manual. As a result, we proposed a new protocol for sewer condition assessment, in which characteristics of sewer pipes are considered by segment. In reference to the PIM-3, the extent of ground subsidence was adopted to be of importance, and renewal scores increased in accordance with weighting of defects causing structural backfill materials. Also, defect grades of 'Hole' were extended to 5 levels of the grading, and 'Surface Damage' was excluded in defect assessment. The addition of 'Buckling' resulted in reduction of weights in 'Surface Damage' and 'Lining Defects'.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.17 no.5
• /
• pp.553-561
• /
• 2015

In this study, the performance assessment criterion for reasonable maintenance of shield TBM tunnel was presented. The performance assessment items such as crack, leakage, breakage, spalling, exfoliation/detachment, efflorescence, quality condition, exposure of steel, carbonation, faulting step, bolts condition, drainage condition, ground condition, contact section condition and conduit condition were selected by analyzing domestic and foreign performance assessment criterions and investigating segment lining deterioration cases through the site investigation and in-depth inspection analysis result on the shield TBM tunnel. In addition, the reasonable weight using AHP (Analytic Hierarchy Process) were estimated.

• Journal of the Korean Geosynthetics Society
• /
• v.6 no.4
• /
• pp.15-20
• /
• 2007

Recently, the demand for industrial and residental land are increasing with economic growth, but it is difficult to acquire areas for development with good ground condition. For efficient and balanced development of land, new development projects are being carried out not only the areas with inland but those with the soft ground as well. As soft grounds have complex engineering properties and high variations such as ground subsidence especially when their strength is low and depth is deep, we need to accurately analyze the engineering properties of soft grounds and find general measures for stable and economic design and management. Vertical drain technology is widely used to accelerate the consolidation of soft clay deposits and dredged soil under pre-loading and various types of vertical drain are used with there discharge capacity. Under field conditions, discharge capacity is changed with various reason, such as soil condition, confinement pressure, long-term clogging and folding of vertical drains and so on. Therefore, many researcher and engineer recommend the use of required discharge capacity. In this paper, the experiment study were carried out to obtain the discharge capacity of six different types of vertical drains by utilizing the large-scale model tests and discharge capacity, degree of consolidation with the time elapsed.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.03b
• /
• pp.87-92
• /
• 2000

In excavation of tunnels especially located in shallow depth, it is not rare to meet geological change in excavation progress worse than expected in the initial design stage. This paper present a case study on the re-design of excavation and support system of a shallow tunnel under construction where it meets the unexpected bad geological condition during excavation. The detailed geological investigation shows that the rock mass is heavily weathered and fractured with RMR value less than 20. Considering this geological condition, the design concept is focused on the reinforcement of the ground preceding the excavation of tunnel. Two design patterns, LW-grouting & forepoling with pilot tunnelling method and the steel pipe reinforced grouting method, are suggested. Numerical analysis by FLAC shows that these two patterns give the tunnel and roof ground stable in excavation process while the original design causes severe failure zone around the tunnel and floor heaving. In point of the mechanical stability and the degree of construction, the steel pipe reinforced grouting technique proved to be good for the reinforcement of heavily fractured rock mass in tunnelling. This assessment and design process would be a guide in the construction of tunnels in heavily weathered and fractured rock mass situation.

• Tunnel and Underground Space
• /
• v.16 no.6 s.65
• /
• pp.467-475
• /
• 2006

The use of face bolt method has been increasing abroad recently. Hence, many tests and measurements are being conducted and reported. Also, it is well hewn that determination of the installation number of foe bolts in the design stage is very difficult due to difference of the ground condition and the type of a bolt to be used. First of all, the type, the number, etc. of bolts used in various tunnel construction sites, investigated, are analyzed. The relationship between bolt and ground condition could not be found because bolts have been used with the other support methods in many cases. In the laboratory test and numerical analysis based on the site investigation, the behavior of ground and pipes installed on the tunnel face to support has been examined. Especially, the installed number is focused on. According to the result of tests, the surface settlement and the axial displacement of the face decrease exponentially as the number of installed bolts increases.

• Journal of the Korean GEO-environmental Society
• /
• v.3 no.1
• /
• pp.27-36
• /
• 2002

This study is about the applicability of copper slag as the ground improvement material. By the geo-technical characteristics of the copper slag and by the effect of consolidation and under drainage condition, it is proved that the copper slag can be used for ground improvement material as substitution for sand. As a result of laboratory tests, it was shown that the permeability of the copper slag was similar to that of sands under the vertical drainage condition. In addition, the copper slag showed higher critical hydraulic gradient than that of sand under up-ward vertical flow state. The copper slag has potential safety against piping and it has internal stability of particles. The conclusion is that the copper slag is suitable for drainage and filter material.

• Journal of Soil and Groundwater Environment
• /
• v.21 no.3
• /
• pp.64-81
• /
• 2016

To analyze the influence of various groundwater flow rates (specific discharge) on BHE system with balanced and unbalanced energy loads under assuming same initial temperature (15℃) of ground and groundwater, numerical modeling using FEFLOW was used for this study. When groundwater flow is increased from 1 × 10⁻⁷ to 4 × 10⁻⁷m/s under balanced energy load, the performance of BHE system is improved about 26.7% in summer and 22.7% at winter time in a single BHE case as well as about 12.0~18.6% in summer and 7.6~8.7% in winter time depending on the number of boreholes in the grid, their array type, and bore hole separation in multiple BHE system case. In other words, the performance of BHE system is improved due to lower avT in summer and higher avT in winter time when groundwater flow becomes larger. On the contrary it is decreased owing to higher avT in summer and lower avT in winter time when the numbers of BHEs in an array are increased, Geothermal plume created at down-gradient area by groundwater flow is relatively small in balanced load condition while quite large in unbalanced load condition. Groundwater flow enhances in general the thermal efficiency by transferring heat away from the BHEs. Therefore it is highly required to obtain and to use adequate informations on hydrogeologic characterristics (K, S, hydraulic gradient, seasonal variation of groundwater temperature and water level) along with integrating groundwater flow and also hydrogeothermal properties (thermal conductivity, seasonal variation of ground temperatures etc.) of the relevant area for achieving the optimal design of BHE system.

• Mycobiology
• /
• v.34 no.4
• /
• pp.206-208
• /
• 2006

To produce an artificial fruiting body of Armillaria mellea on the oak sawdust medium, seven strains of A. mellea were used. The top surface of oak sawdust medium covered with ground raw carrot was inoculated with each of 7 strains and cultured for 30 days at $25^{\circ}C$ in the dark condition until the mycelia of A. mellea completely colonized the medium from top to bottom. Then, the mycelia which were fully covered on the top surface of the medium were scratched slightly with a spatula and filled with tap water for 3 hours. To induce the primordial formation, the 7 strains of A. mellea were transferred to the growth chamber under the illumination (350 lux) of 12 hours and relative humidity of $85{\pm}5%$ in a day and then cultured at $16{\pm}1^{\circ}C$. Only A. mellea IUM 949 could form primordia on the sawdust medium, but the other strains did not make primordia at the same condition. The primordia of A. mellea IUM 949 were formed 10 days after complete colonization of the medium and the fruiting bodies were produced 7 days after a primordial formation. The experimental results suggested that IUM 949 strain might be a good candidate for mass production of fruiting bodies of A. mellea.