• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.479-486
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• 2003

The characteristics of harmonic phase angles and phase angle differences contained in earthquake ground motions such as El Centre 1940 NS, Taft1 1952 NS, Hachinohe 1968 NS and Mexico 1985 are figured, which have been mostly overlooked in contrast with the importance placed on harmonic amplitudes. Recently, performance based design method is used for seismic design and seismic retrofitting, which needs nonlinear response analysis, there must be earthquake ground accelerations which contain the phase angle, the phase angle difference and energy input spectrum characteristics of the zone considered to be constructed building structures. To make clear the importance of phase angle differences, responses of 4 recorded earthquake ground motions, 4-earthquake ground motions normalized by 110 gal and 4 artificial earthquake motions compatible to the seismic building code of Korea are compared.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.141-148
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• 2006

This study describes a generation of artificial earthquake wane compatible with seismic design spectrum. In seismic response analysis of building structures, the input ground accelerations have considerable effect on dynamic characteristics of structures. Therefore, it is important to properly select input ground motions for seismic response analysis. In this paper, the artificial earthquake wave are generated according to previously recorded earthquake waves in past earthquake events. The artificial wave have identical phase angles to the recorded earthquake wane, and their overall response spectra are compatible with seismic design spectrum with 5% of critical viscous damping. Each simulated earthquake wave has a identical phase angles to the original recorded ground acceleration, and match to design response spectra in the range of period from 0.02 to 10.0 seconds. It is concluded that the artificial earthquake waves simulated in this paper ate applicable as input ground motions for a seismic response analysis of building structures.

• Earthquakes and Structures
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• v.3 no.3_4
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• pp.435-455
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• 2012

An impact on the ground surface may represent several phenomena, such as a crash of an airplane or an explosion or the passage of a train. In order to analyze and design structures and equipment to resist such a type of shocks, the response spectra for an impact on the ground must be given. We investigated the half-space motions due to impact using the finite element method. We performed extensive parametric analyses to define a suitable finite element model and arrive at displacement time histories and response spectra at varying distances from the impact point. The principal scope of our study has been to derive response spectra which: (a) provide insight and illustrate in detail the half-space response to an impact load, (b) can be readily used for the analysis of structures resting on a ground subjected to an impact and (c) are a new family of results for the impact problem and can serve as reference for future research.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.23-24
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• 2022

There are many demands for vertical extension construction method in domestic large cities. In this paper, we analyzed and presented the results of examining the cases of ground floor extension and basement extension using the jack pile method. Since the Jack Pile method presses in all the piles without excavating the ground, the bearing capacity of the all the piles can be checked. It was investigated as a safe construction method unlike other small-diameter pile construction methods during underground extension.

• Geomechanics and Engineering
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• v.16 no.3
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• pp.285-293
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• 2018

In densely populated urban areas with a large amount of infrastructure, ground subsidence events can result in massive casualties and economic losses. In South Korea, the incidence of ground subsidence in urban areas has increased in recent years and the number of underground cavities suspected of causing such events has significantly increased. Therefore, it is essential to develop techniques to prevent the occurrence of underground and ground subsidence. In this study, a field test, laboratory test, and numerical analysis were conducted to determine the optimal compaction degree of the upper support layer of any underground cavity below the level of sewer pipes in order to prevent such cavities from collapsing and leading to ground subsidence accidents. During the field test, an underground cavity was simulated using ice, and the generation of the cavity was confirmed using ground penetrating radar. The ground investigation was performed using a cone penetration test, and the compaction of the ground where ground subsidence occurred was evaluated with a laboratory test. The behaviour of the ground under various conditions was predicted using a numerical analysis based on the data obtained from the field test and previous studies. Based on these results, the optimal compaction degree of the ground required to prevent the underground cavity from causing ground subsidence was predicted and presented.

• Korean Journal of Remote Sensing
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• v.35 no.6_1
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• pp.973-985
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• 2019

In this paper, we propose a method to separate the ground and building areas and generate building models automatically through planarity analysis using UAV (Unmanned Aerial Vehicle) based point cloud. In this study, proposed method includes five steps. In the first step, the planes of the point cloud were extracted by analyzing the planarity of the input point cloud. In the second step, the extracted planes were analyzed to find a plane corresponding to the ground surface. Then, the points corresponding to the plane were removed from the point cloud. In the third step, we generate ortho-projected image from the point cloud ground surface removed. In the fourth step, the outline of each object was extracted from the ortho-projected image. Then, the non-building area was removed using the area, area / length ratio. Finally, the building's outer points were constructed using the building's ground height and the building's height. Then, 3D building models were created. In order to verify the proposed method, we used point clouds made using the UAV images. Through experiments, we confirmed that the 3D models of the building were generated automatically.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.19 no.4
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• pp.39-52
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• 2023

This study analyzes the energy performance of a elderly care center building and the applicability of a ground source heat pump (GSHP) system through simulation approach. For this purpose, a building information modeling (BIM) program and an energy performance calculation program were used. The impact of the mechanical ventilation system on the energy requirements of the heating and cooling system and the indoor environment was also analyzed, focusing on the change in indoor carbon dioxide (CO₂) concentration, which is a representative indicator of the indoor environment (air quality). The simulation results showed that the target building exceeds Level 7 in terms of simulated primary energy consumption or actual energy consumption. In addition, it was analyzed that the target building could not maintain the indoor CO₂ concentration below the standard concentration by natural ventilation through window opening alone. Combining the GSHP system with the mechanical ventilation system (Case B and Case C) can further reduce the overall energy consumption by reducing the amount of outdoor air introduced by opening windows. The cost savings compared to the baseline case are estimated to be 67.3% for Case A, 63.7% for Case B, 65.5% for Case C, and 42.5% for Case D. It is necessary to analyze the impact of various renewable energy technologies and passive ones on the energy performance and indoor environment of elderly care centers.

• Journal of the Korean Geotechnical Society
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• v.37 no.10
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• pp.77-87
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• 2021

Several studies have been conducted to analyze, predict, and prevent the risk of ground subsidence occurring in urban areas. Nevertheless, there is insufficient research effort on risk analysis that utilizes the correlation between the density of underground structures (i.e., the spatial quantity of buried objects installed in the ground around the interested area) and the occurrence of ground subsidence. In this paper, a study was conducted to analyze the line density of underground structures using GIS-based spatial information data, and to link this with the recorded ground subsidences. An optimization algorithm was developed to maximize the correlation between the line density of 29 recorded ground subsidences and 6 types of underground structures that occurred between 2010 and 2015 for the analysis area. The concept of normalized line density was also proposed for the analysis. The normalized line density of the analysis area was divided into five grades (Grade 1: lowest, Grade 5: highest). When the optimization algorithm was applied, the case where the normalized line density was Grade 4 or higher at the location of the recorded ground subsidences was about > 80%. It is thought that the density analysis result of underground facilities can be applied to the ground subsidence risk analysis by using the proposed optimization algorithm.

• Journal of the Korean Solar Energy Society
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• v.32 no.spc3
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• pp.185-193
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• 2012

Recently rapid urbanization facilitates development of high-rise building complex including apartment and office building in urban area. Many problems related with high -rise building are reported. Especially, unpleasant strong winds in pedestrian area are frequently encountered around the high-rise building. CFD simulation methods are used to analyze the wind environment of pedestrian level in high-rise building block. However, the results show differences between CFD and measurement. This difference is attributed to improper use of CFD. Conventional CFD simulation for wind environment around high-rise building does not describe the effect of trees, shrubs and plants near ground which affect the wind environment of pedestrian level. Canopy model can be used to reproduce the aerodynamic effects of trees, shrubs and plants near ground. In this paper, CFD simulation methods coupled with the tree canopy model to predict wind environment of pedestrian level in high-rise residential building block were suggested and the validity was analyzed by comparison between measurement and CFD results.

• International Journal of High-Rise Buildings
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• v.3 no.3
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• pp.167-171
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• 2014

TORANOMON HILLS is the main building of a large-scale re-development project located in the center of Tokyo. This high-rise building has a height of 247 m and 52 floors above ground, 5 floors below ground, and $62m{\times}80m$ in plan. It is used as hotel, residential facilities, offices, shops and conference facilities. The super structure is mainly a rigid steel frame with response-control devices, using concrete-filled steel tube columns. The underground section is a mixed structure composed of steel, steel-reinforced concrete and reinforced concrete framings. The piled-raft foundation type is used. The remarkable feature of this high-rise building is that the motorway runs through the basements of the building, which makes it stand just above the motorway. This condition is an important factor of the building design. The plan shape is designed to fit along the curve of the motorway. Special columns at the corners are required to avoid placing columns in the motorway. This special column is a single inclined column in the lower floors that branches into two columns in the mid-floors to suit the column location in the upper floors. The cast steel joint is used for the branching point of each special column to securely transfer the stress.