• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.3
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• pp.29-35
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• 1997

The megastructure combined with the modular concept is an effcient structural system adequate for ultra-tail buildings for the future. An ingeneous structural control system can be developed by separating the internal subframe in one or many modules from the external megaframe, thus taking advantage of the effect of tuned mass dampers without adding any aditional mass. This so called mega-subcontrol system is generally modeled by a 20DF system for parametric study and for finding optimal values of the parameters. In this study the equation of motion for the system is obtained frist and the preconditions for the simplified modeling are investigated. Finally the optimal value for the subsreucture strffness is fomputed with given mass and damping ratios and transfer functions for responses are abtained for white noise ground exitation to verify the effectiveness of the mega-subcontrol system.

• Journal of Wetlands Research
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• v.21 no.spc
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• pp.90-97
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• 2019

In recent years, flood due to the consecutive storm events have been occurred and property damage and casualties are in increasing trend. This study calls the consecutively occurred storm events as a mega rainfall scenario and the discharge by the scenario is defined as a mega flood discharge. A mega rainfall scenario was created on the assumption that 100-year frequency rainfall events were consecutively occurred in the Gyeongancheon stream basin. The SSARR (Streamflow Synthesis and Reservoir Regulation) model was used to estimate the mega flood discharge using the scenario in the basin. In addition, in order to perform more reasonable runoff analysis, the parameters were estimated using the SCE_UA algorithm. Also, the calibration and verification were performed using the objective functions of the weighted sum of squared of residual(WSSR), which is advantageous for the peak discharge simulation and sum of squared of residual(SSR). As a result, the mega flood discharge due to the continuous occurrence of 100-year frequency rainfall events in the Gyeongan Stream Basin was estimated to be 4,802㎥/s, and the flood discharge due to the 100-year frequency single rainfall event estimated by "the Master Plan for the Gyeongancheon Stream Improvement" (2011) was 3,810㎥/s. Therefore, the mega flood discharge was found to increase about 992㎥/s more than the single flood event. The results of this study can be used as a basic data for Comprehensive Flood Control Plan of the Gyeongan Stream basin.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2010.05a
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• pp.17-19
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• 2010

This paper describes the possibility of the raft thickness reduction for mega foundations system of super high-rise buildings through a case study on domestic and foreign super high-rise buildings. In case of super high-rise buildings, the size of foundations, especially raft becomes wider and deeper because of heavy upper load. It is difficult to pour concrete of this kind of mega foundation, and cracks by hydration heat could happen. Therefore, there are several ways to reduce the raft thickness of mega foundations. Piled-raft could be the one because moment and shear load that the raft subjects on by soil reaction are lower. The effect of the piled-raft foundation on the raft thickness reduction could be confirmed by comparison of super high-rise buildings with pile, piled-raft and mat foundation. Furthermore, it was showed that the raft thickness could be more reduced by locating piles right under the vertical members of super structures.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.716-719
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• 2008

Yongsan International business Center, Incheon Songdo City, Roppongihill sand Midtown, including the most of latest internal and external construction projects become larger and more complicated than before. Mega project is one of most complicated project type as public and private sectors involve and the space will be construed in all directions i.e. horizontal, vertical, underground and ground. Therefore mega projects need a new program management information system to start the project's success. So this paper proposes a platform design study to intelligent program management information systems to mange mega projects.

• Explosives and Blasting
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• v.23 no.1
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• pp.55-64
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• 2005

Safe and cheap emulsion explosives have recently replaced the existing CD explosives in order for people to reduce the prime cost and to prevent the safety accidents from happening in construction and civil engineering sites. However, the emulsion explosives have been in reality fared with difficulties in terms of the blasting force when using them in the tunnel constructed in the rock mass composed of hard rock. In this regards, this study is to verify their blasting efficiency and possibility of construction by applying MegaMEX, one of the high performance Emulsion explosives, to the rock mass of hard rock. In terms of their blasting efficiency such as advance ratio and fragmentation, it has turned out that they have overcome the limit of the existing Emulsion explosives and they have had the equivalent level of MegaMITE, one of the GD(Gelatin dynamite) types of explosives while they have been also advantageous to the environmental aspects.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2002.11a
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• pp.133-138
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• 2002

Recently, mega-float offshore structure is studied as one of the effective utilization of the ocean space. And mega-float structure are now being considered for various applications such as floating airports, container yard, offshore cities and so on. This mega-float structure is relatively flexible compared with real floating structures like large ships. when we estimate dynamic responses of these structures in waves, the elastic deformation is important, because vertical dimension is small compared with horizontal. The analysis of the dynamic response as it receives regular wave is studied. The finite element method is used in the analysis of structural section of this model. And the analysis is carried out using the boundary element method int eh fluid division. In order to know the characteristics of the dynamic response of the mega-float structures, effects of wavelength, water depth, and wave direction on dynamic response of the floating structure are studied by use of numerical calculation.

• Journal of Navigation and Port Research
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• v.27 no.1
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• pp.49-54
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• 2003

Recently, mega-float offshore structure is studied as of the effective utilization of the ocean space. And mega-float structure are now being considered for various applications such as floating airports. container yard, offshore cities and so on. This mega-float structure is relatively flexible compared with floating structures like large ship. When we estimate dynamic responses of these structures in waves, the elastic deformation is important, because vertical dimension is small compare with horizontal. the analysis of the dynamic reponses as it receive regular wave is studied. The finite element method is used in the analysis of structural section of this model. And the analysis is carried out using the boundary element method in the fluid division. In oder to know the characteristics of the dynamic response of the mega-float structures, effects of wavelength, water depth, and wave direction on the dynamic response of the floating structure are studied by use of numerical calculation.

• Steel and Composite Structures
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• v.45 no.6
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• pp.797-818
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• 2022

Steel-precast ultra-high-performance concrete (UHPC) composite beams with demountable high-strength friction-grip bolt (HSFGB) shear connectors can be used for accelerated bridge construction (ABC) and achieve excellent structural performance, which is expected to be dismantled and recycled at the end of the service life. However, no investigation focuses on the demountability and reusability of such composite beams, as well as the installation difficulties during construction. To address this issue, this study conducted twelve push-out tests to investigate the effects of assembly condition, bolt grade, bolt-hole clearance, infilling grout and pretension on the crack pattern, failure mode, load-slip/uplift relationship, and the structural performance in terms of ultimate shear strength, friction resistance, shear stiffness and slip capacity. The experimental results demonstrated that the presented composite beams exhibited favorable demountability and reusability, in which no significant reduction in strength (less than 3%) and stiffness (less than 5%), but a slight improvement in ductility was observed for the reassembled specimens. Employing oversized preformed holes could ease the fabrication and installation process, yet led to a considerable degradation in both strength and stiffness. With filling the oversized holes with grout, an effective enhancement of the strength and stiffness can be achieved, while causing a difficulty in the demounting of shear connectors. On the basis of the experimental results, more accurate formulations, which considered the effect of bolt-hole clearance, were proposed to predict the shear strength as well as the load-slip relationship of HSFGBs in steel-precast UHPC composite beams.

• The Journal of the Korea Contents Association
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• v.10 no.11
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• pp.318-328
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• 2010

This paper as basic work on the regional economic policy of Korean government considers economic conditions and fundamentals of the cold started 5+2 mega-regional economic zones and makes a comparative study of regional economic power of national mega-regional economic zones based on the established economic indicator. Therefore, this study aims to consider henceforward policy direction of the mega-regional economic zone and the validity of the regional economic policy, which promote autonomous mega-regional economic zone in dimension to secure the global competitiveness. According to the comparison result of regional economic power index, the capital area had absolute superiority, while Gangwon, Honam and Jeju areas were relatively weak. Since the given regional conditions are dissimilar, the government must consider regional characteristics and economic fundamentals carefully, as they push henceforth regional development policy for the mega-regional economic zone. What is more, the government should promote a balance of the regional development, through to maintain demand-based policy and demand-pull policy flexibly, which are based on demand analysis, as well as unequal quota budget and policy for regions, which are relatively falling behind in terms of development and income.

• Architectural research
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• v.12 no.1
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• pp.57-64
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• 2010

In recent years, interests and studies on the urban regeneration projects have been increased and largely conducted. It is a part of the effort that solves some social and economical problems occurred by deteriorated buildings and degraded infrastructures through new urban regeneration projects or redevelopment projects. However, the urban regeneration projects show the characteristics that can not guarantee in the project performance because the projects have various and complex stakeholders related to these projects and are exposed to lots of risks due to its huge scale. This study proposed the risk performance index method to improve the efficiency of the overall performance measurement for a mega-project by extending from the traditional cost/schedule based performance measurement system. The risk performance index method proposed in this study has a similar system to the EVMS, and makes possible to perform a three dimensional integrated performance measurement in cost/schedule/risk through 18 different indexes that compose the risk performance index.