• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.15-18
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• 2007

The purpose of this study is to suggest a reference for an extensive evaluation about effectiveness of four types of fibers to control plastic shrinkage crack of concrete. So in this study for the practical use in construction field, the plastic shrinkage cracks shown from four types of concrete reinforced by mixing four types of fibers are quantitatively evaluated in points of the workability and compressive strength. Test showed that the mixing of Cl, N, P fibers except for C2 fibers decreased fluidity of fresh concrete. Compressive strengths of four types specimens were similar. Plastic shrinkage cracks were reduced by mixing each fiber, especially C2 fibers was very effective to prevent the plastic shrinkage crack. Therefore the reinforced concrete mixed with C2 fibers exhibited superior mechanical performance than the others.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2001.11a
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• pp.40-45
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• 2001

The purposes of this study were mix design and quality control of high strength concrete for the construction of high rise complex structure. Desired performances of this high strength concrete were slump flow 50$\pm$10cm, air content 4.5$\pm$1.5% and design strength 400kgf/$cm^2$. Experimental flow was that optimal mix design was selected in the indoor experiment and after that, producing test was done in the batcher plant. Excel lent results of experiment was obtained from binder content 475kg/$m^2$ with replacement ratio 10% of fly ash. The results of field application of high strength concrete was sufficiently satisfied both flowability and compressive strength.

• International Journal of Advanced Culture Technology
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• v.1 no.1
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• pp.6-10
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• 2013

The greenhouse control system for educational purpose is designed by personal computer. This system should observe and control the growth conditions for crops in both plastic film and glass greenhouses. In this contribution puts emphasis on construction of greenhouse control system by personal computer under the aim of creating safer, more effective and more economical services. This system is developed for the requirements of the intelligent greenhouse control system and is powered by solar energy. A photovoltaic system with sun tracking module is used for the greenhouse control system.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.3 no.1
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• pp.80-90
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• 2000

This study was carried out to introduce current status and development strategy for an environmental restoration of stream side in Japan, and to consider a methodology which could be effectively applied for the environmental restoration of stream side in Korea. Since the end of 20th century, the native ecology and landscape of Japan remained only a limited areas such as stream side, water side and forest areas. Therefore, recently the works of forest conservation and erosion control of environmental restoration on stream side tended to increased. The strategic prospects of environmental restoration in Japan were summarized as follows : 1. From the ecological point of view, we have to develop a certain method and technology in construction of forest conservation and erosion control to prevent environmental problem from erosion control works. 2. We have to restore not only a continuity of stream side forest from a primitive area to an estuary but also the stream side forest to preserve and restore a stream side vegetation on a primitive watershed areas. 3. We have to improve a method of construction or removal of a structure which were constructed in the stream to restore a water side environment and an interaction system for an integration on a forest land, stream, and erosion control. Additionally, we have to establish an integrated evaluation method and an enforcement system after investigation of influences on natural environment, stream, and forest etc. 4. We have to conduct an integrated research to investigate the ecosystem of stream side, and construct environmentally friendly water park and erosion control park which considered natural environment and its landscape. Additionally, we need to introduce and adopt a natural style stream construction method to restore a water side areas.

• Earthquakes and Structures
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• v.20 no.1
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• pp.39-53
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• 2021

By means of installing sloped rolling-type seismic isolators (SRI), the horizontal acceleration transmitted to the to-be-protected object above can be effectively and significantly reduced under external disturbance. To prevent the maximum horizontal displacement response of SRI from reaching a threshold, designing large and conservative damping force for SRI might be required, which will also enlarge the transmitted acceleration response. In a word, when adopting seismic isolation, minimizing acceleration or displacement responses is always a trade-off. Therefore, this paper proposes that by exploiting the possible information provided by an earthquake early warning system, the damping force applied to SRI which can better control both acceleration and displacement responses might be determined in advance and accordingly adjusted in a semi-active control manner. By using a large number of ground motion records with peak ground acceleration not less than 80 gal, the numerical results present that the maximum horizontal displacement response of SRI is highly correlated with and proportional to some important parameters of input excitations, the velocity pulse energy rate and peak velocity in particular. A control law employing the basic form of hyperbolic tangent function and two objective functions are considered in this study for conceptually developing suitable control algorithms. Compared with the numerical results of simply designing a constant, large damping factor to prevent SRI from pounding, adopting the recommended control algorithms can have more than 60% reduction of acceleration responses in average under the excitations. More importantly, it is effective in reducing acceleration responses under approximately 98% of the excitations.

• Proceedings of the Safety Management and Science Conference
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• 2000.05a
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• pp.9-26
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• 2000

Eventually so as to realize the construction safety, 1 found out the cause of accident and specificities of the construction industry. This study presented to several situations and problems on construction safety. As a result of this study, the below matters must be improved for more effective the construction safety management system. 1. It need to introduce the total construction safety management system. Because there is not effectiveness in the current safety management to the first on the construction field. a. We must consider the safety in the whole parts of the process of the construction and constructors of each part must devide responsibility of the construction safety as a CDM(The Construction Designed Management) used in UK. b. It is desirable to proceed control of safety in the whole parts of the construction to introduce the total safety coordinator that can consult the matters of safety as a law accepted in EU. c. Like management of the construction safety in USA, direction of the construction safety must be made to work exactly by code or manual. d. To improve the organization of the construction safety on the construction field unefficient, it must be introduced safety supervisor, safety coordinator or institutionalization of safety consultant. 2. The law of the construction safety not only have wasteful element but also decrease efficiency by overlapping of regulation, The Ministry of Labour and The Ministry of Construction & Transportation, So laws related with safety must be instituted. a. To realize total safety management, The Ministry of Labour must legislate the basic law about safety management in whole field. b. To legislate the construction safety under one law, and improve efficiency of the overlapping of regulation and the similar law by The Ministry of Construction & Transportation. c. It must be made the law of construction safety that can proper to change of situation in construction. d. The standard of safety must be instituted belong to international level and improved by year. e. We must improve irrational regulation to realize activity of safety self regulating for progress competition in construction industry

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.47.4-47
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• 2002

$\textbullet$ Introduction of UAV Helicopter $\textbullet$ System Specification $\textbullet$ Dynamics of Small EP Helicopter $\textbullet$ Construction of Electrical System $\textbullet$ LQG Control Law $\textbullet$ Simulations $\textbullet$ Results and Analysis

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.485-486
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• 2008

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.531-534
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• 2001

At the beginning of construction, the estimation for the construction duration is very important to effectively control and use labors, builder's equipment, permanent and temporary materials, supplies and utilities, and money. In spite of the importance of the estimation for the construction duration, there is no estimation standard of optimal construction duration in korea. The purpose of this study is to suggest the estimation standard of optimal construction duration that is reasonable and systematical through developing the method for estimating, the construction duration. it is expected to be helpful for estimating, planning and scheduling. The analysis is executed the existing estimation standards and consulting the results of the interviews with the on-site engineers and the concrete compressive stress tests.

• International conference on construction engineering and project management
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• 2017.10a
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• pp.301-312
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• 2017

Quality evaluation and control represent increasingly important concerns for construction quality management. There is an evident need for a standard data model to be used as the basis for computer-aided quality management. This study focuses on how to realize evaluation of construction quality based on BIM and database technology. In this paper, the reinforced concrete main structure is taken as an example, and the BP neural network evaluation model is established by inquiring current construction quality acceptance specification and evaluation standard. Furthermore, IFC standard is extended to integrate quality evaluation information and realize the mapping of evaluation information in BIM model, contributing to the visualization and transfer sharing of evaluation information. Furthermore, the conceptual entity model is designed to build quality evaluation database, and this paper select MySQL workbench system to achieve the establishment of the database. This study is organized to realize the requirement of visualization and data integration on construction quality evaluation which makes it more effective, convenient, intuitive, easy to find quality problems and provide more comprehensive and reliable data for the quality management of construction enterprises and official construction administratiors.