• 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.

• Steel and Composite Structures
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• 제34권6호
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• pp.837-851
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• 2020

This study aims to examine the interface shear behavior between precast high-strength concrete slabs with pockets and steel beam to achieve accelerated bridge construction (ABC). Twenty-six push-out specimens, with different stud height, stud diameter, stud arrangement, deck thickness, the infilling concrete strength in shear pocket (different types of concrete), steel fiber volume of the infilling concrete in shear pocket concrete and casting method, were tested in this investigation. Based on the experimental results, this study suggests that the larger stud diameter and higher strength concrete promoted the shear capacity and stiffness but with the losing of ductility. The addition of steel fiber in pocket concrete would promote the ductility effectively, but without apparent improvement of bearing capacity or even declining the initial stiffness of specimens. It can also be confirmed that the precast steel-concrete composite structure can be adopted in practice engineering, with an acceptable ductility (6.74 mm) and minor decline of stiffness (4.93%) and shear capacity (0.98%). Due to the inapplicability of current design provision, a more accurate model was proposed, which can be used for predicting the interface shear capacity well for specimens with wide ranges of the stud diameters (from13 mm to 30 mm) and the concrete strength (from 26 MPa to 200 MPa).

• 공학교육연구
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• 제18권1호
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• pp.47-53
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• 2015

이 논문의 목적은 메가 시티 서울의 기술상용화 네트워크 도시 형성의 가능성을 고찰하는 데 있다. 1960년대 이후 우리나라는 국가적 차원에서 볼 때, 급속한 경제 성장을 경험하고 있지만, 지역적 차원에서 살펴보면, 서울을 포함한 수도권과 비수도권 간 심각한 지역불균등 발전을 경험하고 있다. 필자는 이와 같은 지역불균등 발전의 해결 방안으로 서울을 중심으로 기술상용화 네트워크 도시 형성의 필요성을 제시하고자 한다. 기술상용화 네트워크 도시는 남북도시협력 축(통일 R&BD 지향-복합기술 R&BD 축), 메가 시티 확장 축(녹색 수출 R&BD 지향-녹색 수출 R&BD 확장 축), 중소도시 연계 축(평창 올림픽 R&BD 지향-생명기술 R&BD축), 메갈로 폴리스 축(R&D-R&BD 연계 협력 지향-기초기술 R&BD 축) 등 4가지 축으로 이루어진다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 춘계학술대회 및 창립 30주년 심포지엄(논문집)
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• pp.301-307
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• 2006

컨테이너 물동량의 급격한 증가와 함께 컨테이너를 운송하는 선박들의 규모도 이전의 증가세와는 비교할 수 없을 정도로 규모는 커지고 있다. 이러한 추세와 함께 초대형선박에 대한 연구도 다양한 시각에서 활발하게 수행되어왔다. 그러나, 대부분의 기존 연구는 주로 선박의 설계, 운영 그리고 항만 하역시설 등 하드웨어적이고 개념적인 부문에 편중되어 있고, 실제 선박운항 측면에서 적정 선박 규모, 적정 기항 항만 수, 요구되는 하역 소요 시간 등 현실적인 연구는 극히 미흡한 실정이다. 따라서 본 논문은 초대형선박의 운영자인 선사들과 사용자인 포워딩업체들을 대상으로 초대형선의 예상 최대규모, 선호도, 이용 시 문제점과 예상 하역시간 등을 조사 분석하고, 초대형선의 출현으로 나타날 될 항만기항지 변화에 대하여 예측한다.

• ALGAE
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• 제38권4호
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• pp.283-294
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• 2023

Previous research indicated that free-living sporangial filament keep hollow morph under high-culture density and form bipartite cells under low-culture density, while the following conchospore release was inhibited by high light. Here, we further explored the molecular bases of these affects caused by light and culture density using a transcriptome analysis. Many differentially expressed genes (DEGs) related to carbon dioxide concentration and fixation, photosynthesis, chlorophyll synthesis and nitrogen absorption were upregulated under high-light conditions compared with low-light conditions, indicating the molecular basis of rapid vegetative growth under the former. The stress response- and ion transport-related DEGs, as well as the gene encoding the vacuole formation-brefeldin A-inhibited guanine nucleotide exchange protein (BIG, py05721), were highly expressed under high-density conditions, indicating the molecular basis of the hollow morph of free-living sporangial filaments under high-culture density conditions. Additionally, the brefeldin A treatment indicated that the hollow morph was directly influenced by vacuole formation-related vesicle traffic. Others DEGs related to cell wall components, zinc-finger proteins, ASPO1527, cell cycle and cytoskeleton were highly expressed in the low density with low-light group, which might be related to the formation and release of conchospores. These results provide a deeper understanding of sporangial filaments in Neopyropia yezoensis and related species.

• 한국항해항만학회지
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• 제29권7호
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• pp.635-640
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• 2005

This paper aims to understand and analyze the mega-trends such as trends towards larger vessels due to an increasing trade volume, accordingly fewer port calls, strategic alliances and M&A Increasing degree of concentration through M&A activities in shipping industry results in a decreasing number of shipping finns with an increasing share in the world shipping capacity. But competition is strongly increasing on main trunk routes. Therefore, shipping concentration directly leads to further concentration of port traffic in fewer and larger ports with an increasing competition among neighboring ports.

• 한국항만학회지
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• 제13권1호
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• pp.11-26
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• 1999

The subject of port efficiency is one of the important issues facing port authorities and policy makers today. A number of studies have been undertaken which compare ports in terms of their efficiency. But any port comparison can only be valid and meaningful if a port’s efficiency is compared with a similar port. The main objective of this paper is to introduce a systematic approach to identifying similar ports based on the technique of principal component analysis and cluster analysis. And it seeks to identify the most important factors underlying the port classification. Lack of awareness of which factors differentiate ports has resulted in an unnecessary collection of data which are of limited use in port classification. This paper has identified five groupings of similar ports within which port comparision can be justifiably made. This approach can be used for any future port comparision.

• Architectural research
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• 제12권1호
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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.

• 국제초고층학회논문집
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• 제5권3호
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• pp.221-232
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• 2016

With the booming of construction and property industries in China, the demand for high-rises and mega-scale buildings with more integrated building functions, open- and tailor-shaped outlooks, better connections to municipal infrastructures, and higher grades of building importance has been increasing in the past two decades. The seismic design and engineering of such modern mega-buildings face engineering challenges such as hazard mitigation of extreme actions and surroundings, integrated structural frameworks and building skins, complex connections, and overall construction efficiency. It is the work of a new generation of civil and structural engineers to enhance engineering efficiency and achieve overall engineering, environmental, and economical effectiveness for these high-rise projects. This paper elaborates the above topics through case studies on the design and construction of four such developments in China. Some rethinking is conducted on evolution in modern seismic engineering and design through innovation to achieve an acceptable level of overall sustainability and building effectiveness.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2007년 가을학술발표회
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• pp.55-77
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• 2007

Currently a large number of high rise building projects are under plan and a mega foundation system to support this high load with safety is requiring. The foundation of a highrise building is displaced by the building load, which influence the behavior of a super structure in reverse. In this aspect, the structural interaction analysis between a foundation and a super structure is necessary. In this study, the relationship of a superstructure of building and a foundation has been reviewed, considering the tendency of design from a capacity driven design to a performance design. Two different case studies have been introduced to help understand this relationship in more specific, the first case is the high rise building founded on a mat system on rock and the second is that on large diameter bored piles on soft ground condition.