• Geomechanics and Engineering
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• v.30 no.2
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• pp.169-185
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• 2022

The urbanization and increasing rate of population demands effective means of transportation system (basement and tunnels) as well as high-rise building (resting on piled foundation) for accommodation. Therefore, it unavoidable to construct basements (i.e., excavation) nearby piled foundation. Since the basement excavation inevitably induces soil movement and stress changes in the ground, it may cause differential settlements to nearby piled raft foundation. To understand settlement and load transfer mechanism in the piled raft due to excavation-induced stress release, numerical parametric studies are carried out in this study. The effects of excavation depths (i.e., formation level) relative to piled raft were investigated by simulating the excavation near the pile shaft (i.e., H_e/L_p=0.67), next to (H_e/L_p=1.00) and below the pile toe (H_e/L_p=1.33). In addition, effects of sand density and raft fixity condition were investigated. The computed results have revealed that the induced settlement, tilting, pile lateral movement and load transfer mechanism in the piled raft depends upon the embedded depth of the diaphragm wall. Additional settlement of the piled raft due to excavation can be account for apparent loss of load carrying capacity of the piled raft (ALPC). The highest apparent loss of piled raft capacity ALPC (on the account of induced piled raft settlement) of 50% was calculated in in case of H_e/L_p = 1.33. Furthermore, the induced settlement decreased with increasing the relative density from 30% to 90%. On the contrary, the tilting of the raft increases in denser ground. The larger bending moment and lateral force was induced at the piled heads in fixed and pinned raft condition.

• Journal of the Korean Geotechnical Society
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• v.26 no.12
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• pp.31-40
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• 2010

This study describes the three-dimensional behavior of pile foundations based on a numerical study. A series of numerical analyses were performed for connectivity conditions between piles and cap under vertical and lateral loadings. It is shown that a fixed connection between pile and cap is able to transfer significant bending moment through the connection and increases the pile lateral stiffness and the bending moment. Based on the results obtained, it was found that the cross sectional shear force in the raft with fixed head condition was larger than that of pinned head condition. Thus, the reinforcement of pile head and thickness of the raft also increases in fixed pile head condition. From the results, it is found that the overall behavior and cross sectional forces of pile foundations is affected significantly by the pile head conditions. Furthermore, the design of pile foundations with pinned head condition was judged to be less costly and very useful for preliminary design stages.

• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.6
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• pp.65-78
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• 2023

In recent times, the frequency and intensity of natural disasters, such as heavy rains and typhoons, have been increasing due to the impacts of climate change. This has led to a rise in social and economic damages. Rural areas, in particular, possess limited disaster response capabilities due to their underdeveloped infrastructure and are highly vulnerable to flooding. Therefore, it is crucial to establish preventative and responsive measures. In this study, an Inventory-Based Flood Loss Estimation (IB-FLE) method utilizing high-resolution spatial information was developed for estimating flood-related losses in rural areas. Additionally, the developed approach was applied to a study area and compared with the Multidimensional Flood Damage Analysis (MD-FDA) method. Compared to the MD-FDA, the IB-FLE enables faster and more accurate estimation of flood damages and allows for the assessment of individual building and agricultural land losses using up-to-date information. The findings of this study are expected to contribute to the rational allocation of budgets for rural flood damage prevention and recovery, as well as enhancing disaster response capabilities.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.1
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• pp.47-57
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• 2024

Recently, in newly constructed apartment buildings, the exterior wall structures have been characterized by thinness, having various openings, and a significantly low reinforcement ratio. In this study, a nonlinear finite element analysis was performed to investigate the crack damage characteristics of the exterior wall structure. The limited analysis models for a 10-story exterior wall were constructed based on the prototype apartment building, and nonlinear static analysis (push-over analysis) was performed. Based on the finite element (FE) analysis model, the parametric study was conducted to investigate the effects of various design parameters on the strength and crack width of the exterior walls. As the parameters, the vertical reinforcement ratio and horizontal reinforcement ratio of the wall, as well as the uniformly distributed longitudinal reinforcement ratio and shear reinforcement ratio of the connection beam, were addressed. The analysis results showed that the strength and deformation capacity of the prototype exterior walls were limited by the failure of the connection beam prior to the flexural yielding of the walls. Thus, the increase of wall reinforcement limitedly affected the failure modes, peak strengths, and crack damages. On the other hand, when the reinforcement ratio of the connection beams was increased, the peak strength was increased due to the increase in the load-carrying capacity of the connection beams. Further, the crack damage index decreased as the reinforcement ratio of the connection beam increased. In particular, it was more effective to increase the uniformly distributed longitudinal reinforcement ratio in the connection beams to decrease the crack damage of the coupling beams, regardless of the type of the prototype exterior walls.

• Korean Journal of Environment and Ecology
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• v.32 no.3
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• pp.323-331
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• 2018

This study was conducted to examine the effects of constructing streetside urban forests on particulate matter (PM) content in pedestrian paths and open spaces created between the main streets and buildings in a high-rise, high-density urban area. The study site is a 70m-wide open space between Busan City Hall and Jungang-street in Busan, Korea. The results showed that the density of PM differences between the open space and the adjacent main street were small in regions without linear trees and shrub rows during both the weekdays and weekend. On the other hand, the areas with linear trees and shrub rows were found to have significantly higher concentrations of PM compared to the roadway. In particular, sections with linear trees and shrub rows had higher PM levels both on roads and in adjacent open space, indicating that the composition of linear trees and shrub rows increased the concentration of PM in the off-street open space in areas with wide space between the roadway and building. The impact was more significant in the open space than the roadway. This phenomenon can be explained by the fact that PM generated by vehicles flows through the roadside shrubs by rapid wind flow but does not disperse widely in the pedestrian paths where the wind flow was reduced. In this study, we found that the roadside tree and shrub walls slowed the flow of wind, causing vehicle-emitted PM to accumulate if a wide open space was created between the road and building, resulting in higher concentration of PM in the open space. We confirmed that the distance between the road and building was a critical factor for constructing linear trees and shrub rows to reduce PM generated by vehicle traffic.

• The Korean Journal of Petroleum Geology
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• v.5 no.1_2 s.6
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• pp.36-47
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• 1997

This study presents multi-variable sequence model for a broader application of sequence concept proposed by Exxon group. The concept of the multi-variable model is based on the fact that internal organization and boundary type of the sequences are determined by three varying factors including 3rd-order cycles of eustasy, and tectonic movement and sediment influx with 2nd-order changes. Instead of Exxon group's systems tracts, this model adopts parasequence sets as the fundamental building blocks of the sequence, because they are descriptive stratigraphic units simply defined by internal stacking pattern, reflecting interactions of accommodation and sediment influx. Seven sequence types which vary in number and type of internal parasequence sets are formulated as associations of four types of accommodation development and three grades of sediment influx. In the southwestern margin of Ulleung Basin, the multi-variable sequence analysis of shelf-slope sequence shows systematic changes in stratal patterns and the numbs, of constituent parasequence sets (i.e. sequence type). These changes are interpreted to reflect temporal and spatial changes in type and rate of tectonic movement and sediment influx, as a result of back-arc opening and closing. During the back-arc opening, rapid subsidence, continuous rise of relative sea level, and high sediment influx gave rise to sequences dominantly of single progradational parasequence set. In the early stage of back-arc closing accompanied by local contractional deformation, different types of sequences contemporaneously formed depending on the spatial changes in tectonically-controlled accommodation and influx rates. During the subsequent slow back-arc subsidence, rise-dominated relative sea-level cycle was coupled with moderate to high sedimentation rate to have resulted in sequences consisting of $2~3$ parasequence sets.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.6
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• pp.945-954
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• 2019

Cultural property is a valuable asset that connects the past with the present, and cultural heritage is now included in the international agenda of disaster risk reduction. Accordingly, the importance of building resilience of cultural assets has been on the rise, and the necessity of spatial information has been emphasized in building resilience. Therefore, in this study, A methodology for studying the resilience contained in cultural assets through linkage with historical map and time series spatial information is proposed and the proposed methodology was applied to cultural assets located in Gongju area. Georeferencing was performed on time-series images of aerial images and topographical map, and the changes in cultural assets and surrounding areas were found. The width of the river has changed due to the installation of the Keum River Estuary Dam and the dammed pool for irrigation. Nevertheless, the main cultural assets and monuments are located in the high-altitude area and thus have been well preserved. In this study, cultural property resilience was extracted using only map data and in future, it is necessary to conduct research to extract cultural property resilience through analysis of historical records such as geography.

• Journal of the Korean Institute of Landscape Architecture
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• v.44 no.1
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• pp.119-128
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• 2016

Urban park planning has become difficult due to the lack of municipal funds. Thereupon, a special scheme was imposed for city park planning. Since then, a legal amendment was made for economical improvement and more active participation. However, there are a lot of questions about whether it was a suitable direction for parks and where it should be emphasized for public interest. Base on these concerns, this study examined the basis and characteristics of location, creation, and maintenance of private development parks in Japan, which was the policy model of Korean private parks. Location and space planning of private development parks was made up considering an effective green network and disaster prevention function, and a minimum area was about 1.42ha. The minimum area, 1ha, was established on the basis of considering realistic possibilities, disaster protection, and universal validity. It was also amended to consider the standard of type two mid- to high-rise exclusive residential areas and consultation with regional governance. Finally, it was built on the lowest limit of ordinance of the relevant city; for example, 100% of the floor area ratio, 30% of the building coverage ratio, and the maximum height of 11 stories, etc. For maintenance, private and public sectors were working together. Maintenance fees for 35 years (based on $300yen/m^2$ per month) were paid en bloc by the licensee. However, the city was paid for facilities that accompanied excessive maintenance costs. Meanwhile, it seemed difficult to introduce attractive profit facilities because of the limitations in location, usage permission, and introduction equipment; furthermore, there were problems with management authority, and the burden of expenses was deducted. For creating private Korean parks, this study suggested that we should build priority of creating city parks and select appropriate locations first; also, we need to make criteria for location, creation, and standard management rules that are relevant to the whole nation of Korea.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.2
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• pp.99-105
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• 2013

In rapidly developing urban areas that include high-rise, large, and complex buildings, indoor and outdoor maps in GIS become a basis for utilizing and sharing information pertaining to various aspects of the real world. Although an indoor mapping has gained much attentions, research efforts are mostly in 2D and 3D modeling of terrain and buildings. Therefore, to facilitate fast and accurate construction of indoor GIS, this paper proposes a semi-automatic method consisting of preprocessing, 2D mapping, and 3D mapping stages. The preprocessing is designed to estimate heights of building interiors and to identify noise data from point clouds. In the 2D mapping, a floor map is extracted with a tracing grid and a refinement method. In the 3D mapping, a 3D wireframe model is created with heights from the preprocessing stage. 3D mesh data converted from noise data is combined with the 3D wireframe model for detail modeling. The proposed method was applied to point clouds depicting a hallway in a building. Experiment results indicate that the proposed method can be utilized to construct 2D and 3D maps for indoor GIS.

• Journal of the Korea Institute of Building Construction
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• v.16 no.5
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• pp.429-436
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• 2016

Because of the shortage of construction workers due to The rising labor costs and an aging labor force, construction time has been extended. As a solution, The construction time of high-rise buildings can be reduced by adopting precast concrete construction methods. Most relevant studies have focused on the development and structural analysis of such methods and not on their construction management. Therefore, this study focused on the construction management of the hollow precast concrete column (HPC) method. The objective of this study was to evaluate the performance of HPC formulations through the analytic hierarchy process and benefit-cost analysis. After a gap analysis of the available literature and expert interviews, the evaluation criteria were selected. A questionnaire survey was administered to professionals with ample experience in precast concrete construction for the pair-wise evaluation of the benefit and costs of the HPC method. The results show that the benefits of the HPC method outweighed its costs. Therefore, the HPC method is a suitable substitute for the half-slab method.