• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.76-77
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• 2021

compared and reviewed the water repellency and strength characteristics by controlling the surface stamping size and fine aggregate ratio of cement mortar mixed with water repellent as a method to control the ecological imitation surface structure. As a result of measuring the contact angle, the higher the ratio of fine aggregate, the larger the contact angle. The contact angle increased when the surface structure was changed by stamping, and increased as the stamping size became smaller. In the surface stamping of mesh#150, the contact angle was particularly increased.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.3 s.73
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• pp.233-238
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• 2006

In this paper, mixed mode magneto-rheological(MR) damper, which is applicable for vibration control of a small scale multi-story structure, is devised. First, the schematic configurations of the shear, flow, and mixed mode MR dampers are described with design constraints and then the analytical models to predict the field-dependent damping forces are derived for each type. Second, an appropriate size of the mixed mode MR damper is manufactured and its field-dependent damping characteristics are evaluated in time domain. Finally, the performance of the manufactured MR damper which is semi-actively applied to a small scale building excited by earthquake load, is numerically evaluated.

• Steel and Composite Structures
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• v.14 no.4
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• pp.349-365
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• 2013

Structures consisting of concrete and steel parts, which are irregular in damping ratios are investigated. This investigation is a code-based seismic design of such structures. Several practical difficulties encountered, due to inherent differences in the nature of dynamic response of each part, and the different damping ratios of the two parts. These structures are irregular in damping ratios and have complex modes of vibration so that their analysis cannot be handled with the readily available commercial software. Therefore, this work aims to provide simple yet sufficiently accurate constant values of equivalent damping ratios applied to the whole structure for handling the damping irregularity of such structures. The results show that the equivalent damping ratio changes with the height of the building and the kind of the structural system, but it is constant for all accelerations values. Thus, available software SAP2000 applied for seismic analysis, design and the provisions of existing seismic codes. Finally, evaluation of different kinds of structural system used in this research to find the most energy dissipating one found by finding the best value of quality coefficient.

• Journal of the Korean housing association
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• v.15 no.3
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• pp.43-51
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• 2004

The purpose of this study is to examine the physical characteristics of the detached housing area in the housing site development district. The process of this study is to investigate the characteristics of the physical structure and the building use, then to analyze the relationship of physical structure and the building use in the aspect of the morphological characteristics. The case study focuses on the Chil-kok2, An-Siml in Taegu. The streets pattern is composited gird and loop type mixed. The block is composited by 2 lots in general. But the obscurity of organization and character of the streets, the size and shape of lots which is not fit to the building use. A whole residential characters appears high residential density ratio. so residential environment became worse. The improving level of residential environment and efficiency of land use in the detached housing area of the housing site development district, firstly the propriety of the physical structure must be considered about detached house characters, and the housing uses which fit to the physical structure are needed, and also for the concrete realization of this, the designation of district, the zoning of residential area, the guideline of the district design, and establishment of comprehensive master planning in detached housing area are needed in aspect of the housing policy. As the result of this study, it suggests several design guideline to improve housing site development.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.241-242
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• 2019

This technology is a water leak repair technology using composite materials of concrete structures that block leakage of structures by injecting rapid microcement into the face of underground concrete to block water and injecting flexible glycidylacrylate. Rapid micro cement system repair materials are mixed with fine fibers to improve the flexural sensitivity of the material and to form a layer that blocks stabilized water at the back of the structure by allowing rapid and tight spatial filling during injection with high cohesion The glycidylacrylate repair material can control the expansion rate, and the external stress also has the characteristic that the form of the material is not destroyed or separated, which can also be applied to vibrating induced structures that produce repetitive fatigue loads, and has an effective durability in saline, alkali, acid (chloric acid, sulfuric acid, nitric acid).

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.174-175
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• 2022

The blast furnace slag, which is widely used as a cement admixture, has latent hydraulics under the influence of cement hydrate, and fly ash and silica fume mainly cause a pozolane reaction. As a result, the cement structure becomes dense, and it is possible to compensate for defects when concrete is usually made with portland cement alone. When fixing carbon dioxide through reaction with carbon dioxide, the amount of calcium hydroxide in the cement paste is important. The larger the amount of calcium hydroxide, the more active the reaction may occur. It is also an important variable in calculating the depth of neutralization through carbonization. In this study, calcium hydroxide in cement paste using mixed materials was quantified through thermal analysis.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.5
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• pp.73-83
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• 2001

The mass and stiffness of upper wall-lower frame system(mixed building structures) change sharply at transfer floor due to different structural system in upper and lower part. These mixed building structures generally show the stiffness, weight or geometric vertical irregularities. The purpose of this study is to investigate the response characteristics of these structures by push-over analysis and nonlinear time history analysis. For four types of analysed models, only the variation of upper wall stories was considered. The conclusions of this study are following; (1) In the push-over analysis, yielding hinges in beams and columns of lower frame occurred at the base shear of similar magnitude in all models. But as the number of stories of upper wall increases, yielding hinges at ends of coupling beams were observed in the small magnitude of base shear. (2) In the nonlinear time history analysis, yielding of lower frame occurred at beams with as small ground acceleration as 55gal, and in upper walls yielding was concentrated on coupling beams and shear walls near the transfer floor. (3) As the number of stories of upper walls decreases, the story stiffness of the lower frames decreased relatively and the occurrence of soft stories in the lower frame was observed.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.2
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• pp.75-84
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• 2003

Most structures are expected to deform beyond the limit of linearly elastic behavior when subjected to strong ground motion. Seismic evaluation of structure requires an estimation of the structural performance in terms of displacement demand imposed by earthquakes on the structure. The nonlinear response history analysis(NRHA) among various nonlinear analysis methods is the most accurate to compute seismic performance of structures, but it is time-consuming and necessitate more efforts. The nonlinear approximate methods, which is more practical and reliable tools for predicting seismic behavior of structures, are extensively studied. Among them, the capacity spectrum method(CSM) is conceptually simple, but the iterative procedure is time-consuming and may sometimes lead to no solution or multiple solutions. This paper considers a nonlinear direct spectrum method(NDSM) to evaluate seismic performance of mixed building structures without iterative computations, given dynamic property T from stiffness skeleton curve and nonlinear pseudo acceleration $A_{y}$/g and/or ductility ratio $\mu$ from response spectrum. The nonlinear response history analysis has been performed and analyzed with various earthquakes for estimation of reliability and practicality of NDSM with mixed building structures.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.1093-1099
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• 2022

The number of buildings is increasing day by day. The next logical footstep is tackling challenges regarding scarcity of resources and sustainability, as well as shifting focus on existing building structures to renovate and retrofit. Many existing old and heritage buildings lack documentation, such as building models, despite their necessity. Technological advances allow us to use virtual reality, augmented reality, and mixed reality on mobile platforms in various aspects of the construction industry. For these purposes, having a BIM model or high detail 3D model is not always necessary, as a simpler model can serve the purpose within many mobile platforms. This paper streamlines a framework for generating a lightweight 3D model for mobile platforms. In doing so, we use an existing structure's site survey data for the foundation data, followed by mobile VR implementation. This research conducted a pilot study on an existing building. The study provides a process of swiftly generating a lightweight 3D model of a building with relative accuracy and cost savings.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.32-33
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• 2016

This purpose of this study is to find the properties of pore structure and length change of blast furnace slag cement added alkali powder stimulant on shrinkage reducing agent presence. In length change, the specimen added alkaline stimulant was smaller than normal blast furnace slag concrete. And the specimen added shrinkage reduction agent was confirmed to show smaller rate of length change than the length. In MIP analysis of 1day-age, 0.1㎛ subsequent pore amount of the specimen added alkaline stimulant was significantly smaller value the normal blast furnace slag concrete specimen.