• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2010년도 춘계 학술논문 발표대회 1부
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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.

• Advances in Computational Design
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• 제3권1호
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• pp.17-34
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• 2018

Tall buildings are categorized as important structures because of the large number of occupants and high construction costs. The choice of competent lateral load resisting systems in tall buildings is of crucial importance. Bracing systems have long been an economic and effective method for resisting lateral loads in steel structures. However, there are some potential adverse aspects to bracing systems such as the limitations they inflict on architectural plans, uplift forces and poor performances in compression. in order to eliminate the mentioned problems and for cost optimization, in this paper, six 20-story steel buildings and frames with different types of bracing, i.e., conventional, mega-scale and buckling-restrained bracing (BRB) were analyzed. Linear and modal push-over analyses were carried out. The results pointed out that Mega-Scale Bracing (MSB) system has significant superiority over the conventional bracing type. The MSB system is 25% more economic. Some other advantages of MSB include: up to 63% less drift ratio, up to 38% better performance in lateral displacement, up to 100% stiffer stories, and about 50% smaller uplift forces. Moreover, MSB equipped with BRB attests even a better seismic behavior in the aforementioned parameters.

• Journal of Information Processing Systems
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• 제14권5호
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• pp.1114-1135
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• 2018

A multiple classification system based on a new boosting technique has been approached utilizing different biometric traits, that is, color face, iris and eye along with fingerprints of right and left hands, handwriting, palm-print, gait (silhouettes) and wrist-vein for person authentication. The images of different biometric traits were taken from different standard databases such as FEI, UTIRIS, CASIA, IAM and CIE. This system is comprised of three different super-classifiers to individually perform person identification. The individual classifiers corresponding to each super-classifier in their turn identify different biometric features and their conclusions are integrated together in their respective super-classifiers. The decisions from individual super-classifiers are integrated together through a mega-super-classifier to perform the final conclusion using programming based boosting. The mega-super-classifier system using different super-classifiers in a compact form is more reliable than single classifier or even single super-classifier system. The system has been evaluated with accuracy, precision, recall and F-score metrics through holdout method and confusion matrix for each of the single classifiers, super-classifiers and finally the mega-super-classifier. The different performance evaluations are appreciable. Also the learning and the recognition time is fairly reasonable. Thereby making the system is efficient and effective.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2008년도 정기학술발표대회 논문집
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• pp.716-719
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• 2008

용산 국제 업무지구, 인천 송도국제도시, 일본의 록본기힐즈, 미드타운 등 최근의 국내 외의 건설프로젝트의 유형은 주거, 상업, 업무, 공공, 문화, 여가 등이 복합되어 수평 및 수직적인 공간에 입체적으로 배치되는 입체 복합 공간 개발이 주류를 이루고 있다. 입체 복합 공간 개발에서의 메가프로젝트는 다양한 참여주체 간의 복잡한 이해관계, 민간 및 공공 개발 영역의 혼재, 운영유지 및 자산 관리의 중요성 등 복합적이고 상호 조율된 가치를 추구한다. 따라서 이런 메가프로젝트를 성공적으로 수행하기 위해서는 기존의 단위 또는 다중프로젝트관리 시스템과는 다른 종합사업관리 시스템이 필요하다. 이에 본 연구는 메가프로젝트 수행을 위한 지능형 종합사업관리 시스템의 플랫폼 디자인 방안을 제시하여 실제 프로그램 개발에 도움을 주고자 한다.

• Steel and Composite Structures
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• 제22권6호
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• pp.1217-1238
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• 2016

Mega composite structure systems have been widely used in high rise buildings in China. Compared to other structures, this type of composite structure systems has a larger cross-section with less weight. Concrete filled steel tubular (CFST) laced column to box-beam connections are gaining popularity, in particular for the mega composite structure system in high rise buildings. To enable a better understanding of the destruction characteristics and aseismic performance of these connections, three different connection types of specimens including single-limb bracing, cross bracing and diaphragms for core area of connections were tested under low cyclic and reciprocating loading. Hysteresis curves and skeleton curves were obtained from cyclic loading tests under axial loading. Based on these tested curves, a new trilinear hysteretic restoring force model considering rigidity degradation is proposed for CFST laced column to box-beam connections in a mega composite structure system, including a trilinear skeleton model based on calculation, law of stiffness degradation and hysteresis rules. The trilinear hysteretic restoring force model is compared with the experimental results. The experimental data shows that the new hysteretic restoring force model tallies with the test curves well and can be referenced for elastic-plastic seismic analysis of CFST laced column to composite box-beam connection in a mega composite structure system.

• 무역학회지
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• 제44권4호
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• pp.205-220
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• 2019

This article recapitulates the recent changes in trade laws, which may be accentuated due to the intriguing emergence of fortified protectionism and Mega FTAs. It points out the need to formulate not only the corporate strategy for enhancing the product differentiation and architectural capabilities but also the public policy, which comprises the industrial adjustment policy to cope with possible negative impulses caused by the digital trade and foreign direct investment. It is imperative for Korea to facilitate the alignment between corporate strategy and industrial adjustment policy as an effective means of enhancing industrial structure by nurturing those linkage effects between relevant forward and backward industries. Given the drastically volatile trade norms of multi-track trade policies, it may be a pivotal momentum for Korea to pursue a paradigm shift of its trade policy with a prime objective of achieving such an alignment between corporate strategy and industrial adjustment policy, which affords increased value-added and the further development of product or generic technology instead of resorting to the misuses and abuses of economies of scale and production technology for the maximization of export amount.

• Steel and Composite Structures
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• 제43권6호
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• pp.773-784
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• 2022

This paper aims to investigate the axial compressive behavior of reinforced concrete (RC) columns strengthened with self-compacting and micro-expanding (SM) concrete-filled steel tubes (SM-CFSTs). Nine specimens were tested in total under the local axial compression. The test parameters included steel tube thickness, filling concrete strength, filling concrete type and initial axial preloading. The test results demonstrated that the initial stiffness, ultimate bearing capacity and ductility of original RC columns were improved after being strengthened by SM-CFSTs. The ultimate bearing capacity of the SM-CFST strengthened RC columns was significantly enhanced with the increase of steel tube thickness. The initial stiffness and ultimate bearing capacity of the SM-CFST strengthened RC columns were slightly enhanced with the increase of filling concrete strength. However, the effect of filling concrete type and initial axial preloading of the SM-CFST strengthened RC columns were negligible. Three equations for predicting the ultimate bearing capacity of the SM-CFST strengthened RC columns were compared, and the modified equation based on Chinese code (GB 50936-2014) was more precise.

• 한국공간구조학회논문집
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• 제24권2호
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• pp.75-82
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• 2024

Since atypical high-rise buildings are vulnerable to gravity loads and seismic loads, various structural systems must be applied to ensure the stability of the structure. In this study, the authors selected a 60-story twisted-shaped structure among atypical high-rise structures as an analytical model to investigate its structural behavior concerning the outrigger system. The structural analyses were performed varying the number of installed layers and the arrangement of the outrigger system, as well as the placement of the mega column, as design variables. The analysis revealed that the most effective position for the outrigger was 0.455H from the top layer, consistent with previous studies. Additionally, connecting outriggers and mega columns significantly reduced the displacement response of the model. From an economic standpoint, it is deemed efficient to connect and install outriggers and mega columns at the structure's ends.

• Computers and Concrete
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• 제26권2호
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• pp.161-173
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• 2020

Shear keys in precast concrete segmental bridges (PCSBs) are usually match-casting which is very labour intensive. In this research, an innovative match-casting-free construction was proposed by leaving small gap between the convex and the concave castellated shear keys in the joints of PCSBs. Specimen experiment, shear strength analysis and numerical simulation were conducted, investigating the loading performance of this new type of dry joints, the gap dry joints. Compared with match-casting joint specimens, it has been found from experiment that shear capacity of gap joint specimens significantly decreased ranging from 17.75% to 42.43% due to only partially constrained and contacted in case of gap dry joints. Through numerical simulation, the effects of bottom contacting location, the heights of the gap and the shear key base were analyzed to investigate strength reduction and methods to enhance shear capacity of gap joint specimens. Numerical results proved that shear capacity of gap dry joints under full contact condition was higher than that under partial contact. In addition, left contact destroyed the integrity of shear keys, resulting in significant strength reduction. Larger shear key base remarkably increased shear capacity of the gap joint. Experimental tests indicated that AASHTO provision underestimated shear capacity of the match-casting dry joint specimens, while the numerical results for the gap dry joint showed that AASHTO provision underestimated shear capacity of full contact specimens, but overestimated that of left contact specimens.

• Steel and Composite Structures
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• 제22권5호
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• pp.1019-1038
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• 2016

The use of high-strength concrete (HSC) in precast concrete segmental bridges (PCSBs) can minimize the superstructure geometry and reduce beam weight, which can accelerate the construction speed. Dry joints between the segments in PCSBs introduce discontinuity and require special attention in design and construction. Cracks in dry joints initiate more easily than those in epoxy joints in construction period or in service. Due to the higher rupture strength of HSC, the higher cracking resistance can be achieved. In this study, shear behavior of dry joints in PCSBs was investigated by experiments, especially focusing on cracking resistance and shear strength of HSC dry joints. It can be concluded that the use of HSC can improve the cracking resistance, shear strength, and ductility of monolithic, single-keyed and three-keyed specimens. The experimental results obtained from tests were compared with the AASHTO 2003 design provisions. The AASHTO 2003 provision underestimates the shear capacity of single-keyed dry joint C50 and C70 HSC specimens, underestimates the shear strength of three-keyed dry joint C70 HSC specimens, and overestimates the shear capacity of three-keyed dry joint C50 HSC specimens.