• Journal of the Korea Concrete Institute
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• v.19 no.6
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• pp.717-726
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• 2007

If conventional reinforcements are used for high-strength concrete (HSC) structures, a large amount of the reinforcement must be required to compensate for the brittleness of HSC and make the best use of HSC. This raises some structural problems such as steel congestion and an increase in self-weight. Therefore, alternative reinforcing materials and methods for HSC structures are needed. In this study, four full-scale beam specimens constructed with HSC (100 MPa) were tested to investigate the effect of the different shear reinforcements on the shear behavior. These four specimens were reinforced for shear stirrups with normal and high strength steels, headed bars, and carbon fiber-reinforced polymer (CFRP) bars, respectively. In addition, steel fibers were added to the HSC in the two of the specimens to observe their beneficial effects. The use of high strength steels resulted in the improvement of the shear capacity since the shear resistance provided by the shear reinforcements and the bond strength were increased. The specimen reinforced with headed bars also showed a superior performance to the conventional steel reinforced specimen due to the considerably high anchorage strength of headed bar. CFRP bars used in this research, however, seemed to be inadequate for shear reinforcement because of the inferior bond capacity. The presence of the steel fibers in concrete led to remarkable improvement in the ductility of the specimens as well as in the overall cracks control capability.

• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.451-458
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• 2015

The infill-wall strengthening method has been widely used for the seismic performance enhancement of the conventional reinforced concrete (RC) frame structures with non-seismic detail, which is one of the promising techniques to secure the high resisting capacity against lateral forces induced by earthquake. During the application of the infill-wall strengthening method, however, it often restricts the use of the structure. In addition, it is difficult to cast the connection part between the wall and the frame, and also difficult to ensure the shear resistance performances along the connection. In this study, an advanced strengthening method using the externally-anchored precast wall-panel (EPCW) was proposed to overcome the disadvantages of the conventional infill-wall strengthening method. The one-third scaled four RC frame specimens were fabricated, and the cyclic loading tests were conducted to verify the EPCW strengthening method. The test results showed that the strength, lateral stiffness, energy dissipation capacity of the RC frame structures strengthened by the proposed EPCW method were significantly improved compared to the control test specimen.

• Korean Journal of Construction Engineering and Management
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• v.8 no.1 s.35
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• pp.132-140
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• 2007

There is an increase in interest and investment in high-rise housing as it is perceived to be a new value-added market in the construction industry. In constructing a high-rise housing, the finishing works are executed in accompaniment with many other activities that are progressed repeatedly and spontaneously on each floor. It was reported that the duration of finishing works differs according to the management ability of the executing company and has a significant effect on the entire project duration. We suggest a need to concentrate on important management factors by analyzing the factors affecting the productivity of finishing works based on the site characteristics in high-rise housing. There are various complex productivity-affecting factors including the technical factors involved in planning and managing the processes of finishing works. From the viewpoint of planning and management factors, the importance of productivity-affecting factors was analyzed using the Analytic Hierarchy Process (AHP). A continuous examination of the management of high-importance factors will make it possible to improve productivity by enhancing the understanding of productivity-affecting factors of finishing works and suggesting a practical management direction.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4C
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• pp.147-154
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• 2011

Currently NATM tunnels are designed by applying the initial ground loads caused during construction to the primary supports, conisting of shotcrete, steel ribs and rock bolts. For long term considerations, it is assumed that the primary supports lose its functionality and therefore the secondary support, i.e. concrete lining, is design to resist against the entire ground loads. But the steel ribs, usually applied to bad ground conditions, are embedded in shotcrete causing very little corrosion and therefore the assumption that the primary support will lose all of its functionality is too conservative. Also even though shotcrete carbonates in long term, excluding it from design is also too conservative. In this study, we have, through analytical and numerical analysis, set a rational level of support pressure and allowable relaxed rock mass height sustainable by the primary support for long term design. Changes in sectional forces of the concrete lining considering the calculated support pressure of the primary supports was also carried out. Shallow subway tunnels were considered in the analysis with weathered rock and soft rock ground conditions. The analysis results showed that, by considering the support pressure of steel ribs, an economical design of the concrete lining is possible.

• Explosives and Blasting
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• v.28 no.2
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• pp.99-107
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• 2010

Domestic explosive demolition techniques have been developed and applied for low-rise structures up to now. However, the demand for the development of those techniques that can be applied economically, safely and environment-friendly rapidly increases because the old high-rise RC rahmen structures that were built since around 1970s are now required to rebuild. As a result, element technologies of explosive demolition for low-rise structures were applied to take advantage of technology in high-rise structures that performed application testing at Chungang Department demolition field in Daejeon city. It could judge elements technology establishment for high-rise structure demolition and field application and suggest the improvements when the problems occurred to develop High-rise building demolition techniques for method of protection a field test and the dust reduction test. The water cannon test was applied to reduce the dust site and the drilling tests are performed to select the best components for explosives demolition elements techniques of the reliability. This paper shows that we have the ability to remove a high-rise building using environmentally friendly safe and economical explosives demolition method. It would contribute to prevent a foreign company from entering the domestic market and should contribute to acquire competitiveness of domestic demolition industry.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.2
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• pp.37-46
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• 2009

In this study, the seismic performance of the Buckling Restrained Knee Bracing (BRKB) system was evaluated through a pin-connected 1-bay 1-story frame. The BRKB system using a bolted channel section developed was composed of a steel plate as a load-resisting core member and two channel sections as a restrainment of the local and global buckling of the core plate. The main purpose of the BRKB system is to be used as an effective tool to re-strengthen/rehabilitate old low- and mid-rise RC frame buildings, which do not have enough seismic resistance to earthquake loadings. The main variables for the test specimens were the size of the core plates, stiffeners and the use of guide plates. The test results showed that the size of the core plate, which was the main element for the load-resisting member, was the most important parameter to achieve ductile behavior under tension as well as compression, until the maximum displacement exceed twice the design drift limit given by the AISC Seismic Provisions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.13-20
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• 2017

High-rise building shapes are changing from orthogonal to irregular form and the current trend is to arrange members in geometric grid-patterns at the perimeter of buildings. This study proposes a simple model for the preliminary design of a hexagrid high-rise building. The size of the cross section is set to be different at each module and hexagrid unit, which is different from the previous studies in which all hexagrid members were the same. To examine the effect of hexagrid size on structural performance, 60-story hexagrid buildings with 1-, 2- and 4-story high modules are designed and analyzed. Maximum lateral displacement, steel tonnage, load carrying percentage of perimeter frame and combined strength ratio are compared for 15 buildings. As the lateral load carrying capacity of hexagrid structure was inferior to a diagrid structural system, proper lateral stiffness should be allocated to the core frame in a hexagrid structure. The best ratio of flexural to shear deformation was 4 and larger unit size was better in considering constructional cost and structural efficiency. As the maximum lateral displacements of the buildings were within 84%~108% of the limit, the proposed method seems to be applicable to preliminary design of hexagrid buildings.

• Proceedings of KOSOMES biannual meeting
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• 2004.05b
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• pp.43-48
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• 2004

The development of the traffic system has brought relative reduction in aspect of the cost and time distance on the geographical space. SOC(social overhead capital), an express highway and railroad, has a great and absolute effect on the prosperity of community, As Mokpo is one of the community under the influence q West costal highway express and KTX(Korea Train Express), the number of the tourists visiting city of port like Mokpo has increasing gradually, especially at the high-demand season(in Summer). But the coastal passenger boot can't be capable of customers arriving at the port. As a result of this situation, the 'balking' occurs. No 'balking', means the jam of road. In this thesis, by understanding the concept and property of ARENA and simulating operation of coastal passenger boot at Mokpo port, intends to analyze the truth of 'balking' and finds an effective operation method of coastal passenger boot for the solution to the traffic jam. The solution to the jam in the vicinity of port of Mokpo, which try to develop tourism package commodity now, will present the effect of qualitative analysis in giving an opportunity of economic growth of the community, Mokpo.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.8
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• pp.2809-2817
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• 2010

The scholarly concern of train industry has been improved, since country focuses on this field. Especially, train maintenance facility has been studied for construction, because the facility is important to inspect the train that transports passenger and cargo. Various operation plans and criteria are considered to build train maintenance facility. In this paper, the decision making of train maintenance facility for construction is studied and analyzed with simulation, because mathematical theory is restricted to consider various operation plans and criteria. Through simulation, we analyze warm-up after selecting dependent factors, and extract data. The data is used to select a alternative in this problem, Multiple Attribute Decision Making(MADM). Previous study is difficult, complex and subjective for decision making. However, entropy measurement we used help decision maker for decision making, easily, simply, and objectively. This method can have decision maker choose the best alternative in case the train maintenance facility construction is fast revitalized.

• Journal of The Korean Association For Science Education
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• v.37 no.3
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• pp.417-427
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• 2017

Media is the medium that impart information beyond time and space. They refer to characters or images that serve as means to convey information. From old media such as newspapers and television to new media such as the internet and smart phones, media has developed cumulatively with the development of technology. The goal of media education is to develop the understanding of the properties of media, the ability of critical interpretation of media and selective acceptance. Furthermore it is to cultivate the ability to express meaning creatively and communicate through media. I carried out 'the research of Korean classroom instruction models based on media' with Korean language and social studies education researchers from July 2016 to December 2016. This study is a fundamental study of the project. Based on 58 research papers published between 2006 and 2016, research trends and factors were extracted through literature studies related to media-based science learning. The Result has shown that the studies related to media-based science learning is on the rise, and more than half of all researchers studied about elementary school students. The studies were divided into research on students, research on teachers and pre-service teachers, research on smart devices or media contents, and research on the development of digital textbooks. Among the four variables, there were many researches related to students' cognitive and affective development, and the development and application of media contents.