• Journal of the Korean Association of Geographic Information Studies
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• v.10 no.1
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• pp.102-112
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• 2007

Like other organic beings, modern cities change every day. Unlike in the past, changes of space which have been taking place in concentrated spaces during short periods of time have worsened the environment of cities creating environmental problems. In particular, the urban heat-island phenomenon, which is caused by changes in using the earth's surface, has emerged as a key social issue along with health problems and economic difficulties. The Green Network has been introduced as an urban planning approach to solve the urban heat-island phenomenon. This study suggests constructing a Green Network through analyzing the urban heat island phenomenon, land cover classification, and linkage possibility with the Green Network and wind corridors by researching Jung-Gu, and Nam-Gu in Daegu Metropolitan City. In conclusion, this study presented the construction of a broad and detailed Green Network of object areas by assigning Apsan to the southern area and mountain area as the core, two areas of Nam-Gu and six areas of Jung-Gu such as Duryu Park and, Dalsung Park as footholds and other school land and park facility areas as footholds-to-be areas. In particular, Camp Walker, which is connected with Apsan, is not only a foothold but connected to the core, is necessary to preserve after being transferred from the U.S. Army. In addition, assigning the Susung Bridge area of Jung-Gu and the Camp Walker area of Nam-Gu as the wind corridor areas is recommended.

• Journal of the Korean GEO-environmental Society
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• v.21 no.6
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• pp.19-25
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• 2020

In the recent downtown works, there are frequent cases where the work on existing piles is impossible due to the influence from lack of space and surrounding environment. In such cases, there has been growing cases of using the micropile method that is available to work with the small equipment and asserts the bearing capacity of the existing piles. The micropile method is a type of drilled shaft with the diameter of a pile to be around 75 mm~300 mm that, even for a case where it has certain surrounding structure, foundation and spatial obstacle, there is almost no work difficulty and the work is feasible under all types of soil conditions. In addition, the work can be done in places where the ceiling of the building is low with less vibration and noise in the work process that such method is significantly used for foundation reinforcement of existing buildings. With respect to the motion characteristics that are changed depending on the foundational characteristics or when the micropile is applied with compression or tensile force, there is very few studies conducted. Therefore, under this study, through the data analysis of the field loading test regarding the micropile worked in the fields, it clarifies the settlement and characteristics of bearing capacity following the embedded condition of the ingredients and piles that consist the foundation if the compression and tensile force are applied to the micropile, and by facilitating the statistical analysis program, SAS, to carry out the analysis on the main elements influencing on settlement of the micropile and bearing capacity.

• Journal of the Korean Institute of Landscape Architecture
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• v.27 no.3
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• pp.1-17
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• 1999

The purpose of this study is to evaluate the creation techniques of artificial wetland, one of biotopes developed to promote biodiversity in urban areas, and to look for improvement steps. Specifically, artificial wetland creation techniques were categorized into living environment and living creature classification. Being living conditions for creations, habitat environment was reviewed with a focus on water and soil environments. Living creatures were classified into plants, insects, fish, and birds. The evaluation of creation techniques was done in post-construction evaluation while considering the creation of habitats for living creatures. Intervention by users, changes in living environment and living species, and relevance of creation techniques were reviewed. Key results of this study are as follows. (1) Water environment for the living environment of creatures provides a suitable environment conditions for the living of creatures through a process easing the use of piped water. Various water depths and embankment appear to have a positive impact on the living of aquatic life. In particular, embankment covered in soil naturally played an important role as a place for the activities of aquatic insects and young fish as well as the growth of aquatic plants. (2) Various aquatic and ground plants to promote insect-diversity, shallow water, and old-tree logs had contributed greatly in increasing the types and number of insects. Aquatic insects. Aquatic insects were seen much particularly in areas where aquatic plants are rich but water is shallow than any other areas. (3) A space piled with stone to provide habitats for fish was not much used. However, it was observed that fish used embankment built with natural stones and embankment using logs in areas where water is deep. In addition, it was confirmed that 1,500 fish that had been released propagated using various depths and places for birth. (4) It was analyzed that techniques (creation of island, log setting, and creation of man-made bird nests) to provide habitats and to attract birds are not serving their roles. In such a case, it is believed that species had not increased due to the smallness as well as isolated features of the area. Based on theoretical review, they are judged to be areas that are likely to be used when a greater variety of birds is introduced. It is judged that attracting and keeping more birds at the site, such spaces need to be linked systematically in the future in terms of building eco-network while ensuring an adequate living areas. (5) In the study areas, users intervened greatly. As a result, a blockage was created preventing the normal growth of plants and non-indigenous plants were introduced. In order to limit the intervention by users, setting enough buffer zones, and environment education programs were urgently required. D/H=1>Hyangkyo> houses on the river>temples>lecture halls. D/H ratio of the backside areas is as follows. D/H=1>Hyangkyo>houses on the river>lecture halls. 4. Inner garden were planted deciduous than evergreen trees with Lagerstroemia indica. Enclosed dominant trees were planted by Pinus densiflora, Querces seuata. construct GEM strain, and examined for the expression and functional stability in microcosms.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.5
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• pp.121-133
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• 2017

Since the mid 1990s, policies have been actively promoted to improve safety and pedestrian environment around the school such as the improvement of School zone. However, the prevention of accidents was not effective because it did not extend to the school road where the main transportation route for children's commuting takes place. In addition, due to the rapid increase of automobiles, trunk road traffic in the peak time bypasses the back roads, which threatens children's safety and the environment by invading the school area, which is the main living space of children. In this study, the characteristics of domestic children's traffic accidents were investigated and the problems were analyzed by conducting a field survey on Yeouido Secondary School in Seoul and Unjung Elementary School in Gyeonggi Province. In addition, Variable speed limit signs and Beacons were installed in the pedestrian road of comunity including School zone, and the effects of facilities on the speed of vehicles were analyzed. As a result of the analysis, the Variable speed limit sign showed a deceleration effect of about 8.3km/h, and the Beacon showed a phenomenon in which the traveling speed of 0.8km/h increased only slightly. In addition, the traffic violation rate of passenger cars, buses, and lorries decreased by about 3% as a result of investigating the number of traffic violation vehicles before and after installation.

• Journal of the Korean GEO-environmental Society
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• v.21 no.10
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• pp.11-16
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• 2020

Korea's agricultural reservoir is one of the country's major infrastructures and plays an important role in people's lives. However, aging reservoirs are a risk for life and property. Currently, large and small dams and reservoirs have been constructed nationwide for more than 40 years of aging. Dams and reservoirs built nationwide are managed by various institutions. Therefore, it is difficult to manage all dams and reservoirs due to cost and time. Managers in the field with less management personnel and lack of expertise should be able to quickly identify risk factors for multiple reservoirs. In this study, risk factors such as seepage, leakage, settlement slide, crack and erosion were selected. To assess the risk of the items, we used the analytical hierarchical process (AHP), one of the Multi-Criteria Decision Making (MCDM) methods. The analysis showed that seepage has the greatest impact on reservoir collapse. It is judged that the priority of detailed diagnosis can be determined by evaluating the risk of dam reservoir collapse in a convenient way in advance using the calculated weight.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.7
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• pp.109-117
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• 2010

Building a large-scale testbed for Future Internet is very important to evaluate a new protocol and new network architecture designed by clean-slate approach. In Korea, new Future Internet testbed project, called FIRST (Future Internet Research for Sustainable Testbed), has been started since Mar. 2009 to design and test new protocols. This project is working together with ETRI and 5 universities. The FIRST@PC is to implement a virtualized hardware-accelerated PC-node by extending the functions of NetFPGA card and build a Future Internet testbed on the KOREN and KREONET for evaluating newly designed protocols and interesting applications. In this paper, we first briefly introduce FIRST@PC project and explain a 'MAC in IP Capsulator' user-space program using raw-socket in Linux to interconnect OpenFlow enabled switch sites on the KOREN and KREONET. After that, we address test results for TCP throughput performance for varying packet size. The test results show that the software based capsulator can support a reasonable bandwidth performance for most of applications.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.189-198
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• 2011

Although high strength bolts with tensile strength of 1,000 MPa are mainly used in steel structure construction sites throughout the world, new high strength bolts are required owing to the installation of continuous long-span bridges resulting from the development and distribution of high strength steel and ultra-thick steel plates. Currently, high strength bolts with tensile strength of 1,300 MPa are being used. However, as they tend to place a large load on a small section of space, a high strength bolt of high structural performance and screw thread shape with less stress concentration is thought to be more effective. This study conducted analyses in order to develop an improved screw thread shape relative to the KS screw thread shape. A new screw thread shape with less stress concentration and effective load distribution at the time of fastening bolts and nuts was provided upon analysis of the characteristics of screw thread shape. Additionally, in an experimental study, the structural performance of high strength bolts with tensile strength of 1,300 MPa was investigated. The results revealed that the new screw thread shape was more effective than the existing screw thread shape in terms of structural performance and mitigating the stress concentration.

• Tunnel and Underground Space
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• v.8 no.3
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• pp.209-225
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• 1998

Recently, Umbrella Arch Method(UAM), one of the auxiliary techniques for tunnelling, is used to reinforce the ground and improve stability of tunnel face. Because UAM combines the advantages of a modern forepoling system with the grouting injection method, this technique has been applied in subway, road and utility tunnel sites for the last few years in Korea. Also, several research results are reported on the examination of the roles of inserted pipes and grouted materials in UAM. But, because of its empirical design and construction methodology, more qualitative and systematic design sequences are needed. Therefore, above sequences using numerical analysis are proposed and, the effects of some design parameters were studied in this research. In order to acco,mplish these objects, first, the roles of pipe and grouting materials, steel-rib and the others in ground improving mechanism of UAM are clarified. Second, the effects of design parameters are investigated through parametric studies. Design parameters are as follows; 1) ground condition, 2) overburden, 3) geometrical formulation of pipes, 4) grouting region and 5) characteristics of pipes.

• Tunnel and Underground Space
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• v.23 no.5
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• pp.383-391
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• 2013

A number of true triaxial tests on rock samples have been conducted since the late 1960 and their results strongly suggest that the intermediate principal stress has a considerable effect on rock strength. Based on these experimental evidence, various 3-D rock failure criteria accounting for the effect of the intermediate principal stress have been proposed. Most of the 3-D failure criteria, however, are focused on the phenomenological description of the rock strength from the true triaxial tests, so that the associated strength parameters have little physical meaning. In order to confirm the likelihood that the intermediate principal stress dependency of rock strength is related to the presence of weak planes and their distribution to the preferred orientation, true triaxial tests are simulated with the transversely isotropic rock model. The conventional Mohr-Coulomb criterion is extended to its anisotropic version by incorporating the concept of microstructure tensor. With the anisotropic Mohr-Coulomb criterion, the critical plane approach is applied to calculate the strength of the transversely isotropic rock model and the orientation of the fracture plane. This investigation hints that the spatial distribution of microstructural planes with respect to the principal stress triad is closely related to the intermediate principal stress dependency of rock strength.

• Tunnel and Underground Space
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• v.27 no.1
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• pp.39-49
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• 2017

The factor of safety (FOS) is commonly used as an index to quantitatively state the degree of safety of various rock structures. Therefore it is important to understand the definition and characteristics of the adopted FOS because the calculated FOS may be different according to the definition of FOS even if it is estimated under the same stress condition. In this study, four local factors of safety based on maximum shear stress, maximum shear strength, stress invariants, and maximum principal stress were defined using the Mohr-Coulomb and Hoek-Brown failure criteria. Then, the variation characteristics of each FOS along five stress paths were investigated. It is shown that the local FOS based on the shear strength, which is widely used in the stability analysis of rock structures, results in a higher FOS value than those based on the maximum principal stress and the stress invariants. This result implies that the local FOS based on the maximum shear stress or the stress invariants is more necessary than the local FOS based on the shear strength when the conservative rock mechanics design is required. In addition, it is shown that the maximum principal stresses at failure may reveal a large difference depending on the stress path.