Papers by Author: Young Sang Cho

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Authors: Yong Taeg Lee, Seung Hun Kim, Seung Ho Lee, Sang Ki Baek, Young Sang Cho, Seong Uk Hong
Abstract: As the industrial development brings the structures growth, the consumption of the natural aggregate is increasing annually. On the other hand, the amount of the potential aggregate is decreasing with the huge amount of construction waste from the concrete demolition. The annual total amount of natural aggregate consumption estimated 370million tons. And the experts are concerned about the depletion of aggregate which is presumed to be exhausted in 20 years, considering the annual consumption, which is approximately 250million(m³) in construction industry. Along with this issues, the government promotes to use recycled coarse aggregate from the construction waste in consideration of social, economic and environmental aspects. In conclusion, the purpose of this study is to promote to use of recycled coarse aggregate as a future substitute resource and to increase awareness of it as well. This study conducts the experiments by comparing high-strength concrete for the substitution of chosen two companies.
Authors: Young Sang Cho, Sung Chul Hong, Hyun Suk Jang, Min O Kang
Abstract: The purpose of this study is to enhance productivity and economic value with precise object information generation and reinforcement quantity take-off by developing the Automation Reinforcement Placement System of Foundation (ARPF). This study was conducted by selecting the most basic form, spread footing, and no force was applied on the foundation other than axial force. For the development of ARPF, variables that should be input into the typical programs directly by users were minimized through developing the reinforcement placement algorithm by using visual C# based on the reinforced concrete structure design standard. The process of reinforcement detail placement formation was performed in the Tekla Structure (TS) that has outstanding accessibility and usability of API. Objects made by applying ARPF enable information confirmation and modification, as typical ones. Through this process using ARPF, rapid and precise reinforcement quantity take-off and footing bar placement are possible. If modeling is performed on the Tekla Structures by using ARPF, a detailed 3D reinforcement placing drawing, not 2D, can be created. It is expected that this method may take a smaller amount of time and effort than the typical drawing generation method that users had to generate objects or input information themselves.
Authors: Yong Taeg Lee, Seong Uk Hong, Hyun Suk Jang, Sang Ki Baek, Young Sang Cho
Abstract: National effort to recycle construction waste as structural concrete usage of high economic value is ongoing, but performance rate of recycling is a low-level due to a lack of awareness on the recycled aggregates. Accordingly, the goal of this study was to verify the structural applicability of recycled aggregates. This study compared a compressive strength based on the replacement ratio of natural aggregate and recycled aggregate, and analyzed a correlation of wave velocity due to the increase in compressive strength under the same condition. The 『design standard strength – replacement ratio of recycled coarse aggregate』 was set to total 12 combinations by applying 0, 30, 50, 100[%] replacement ratio of recycled coarse aggregate to 21, 27, 35[MPa] to the design standard strength. During the experiment of fracture strength, strength degradation due to the replacement rate of recycled coarse aggregate did not occur, and it was found that the wave velocity also increased along with an increase in strength due to the age of recycled coarse aggregate concrete.
Authors: A Ra Ko, Je Hyuk Lee, Hyun Suk Jang, Seung Il Lee, Young Sang Cho
Abstract: Structural building information modeling (S-BIM) for reinforced concrete walls based on parametric technique has studied. There are structural analysis and design packages for reinforced concrete structures. 3D BIM platforms which are recently developed and widely adopted in the construction industry are mostly experiencing a difficulty in interoperability with structural analysis and design packages. The modeling of reinforcement placement in the reinforced concrete structures can not be performed using current BIM platforms based on the result of structural analysis and design. This study develops the algorithm and implementation of integrated reinforcement bar placement system by creating a database that stores the results of structural analysis and design so that overall reinforced concrete model including re-bar can be built. Utilization of S-BIM can reduce the time of engineering, the production of working drawing and shop drawing.
Authors: Young Sang Cho, Sang Ki Baek, Yong Taeg Lee, Seung Hun Kim, Jun Ho Park, Seong Uk Hong
Abstract: Recently, many structures which were built about 30 years ago are watched by reconstruction. Demolished concrete is occurred in the process and these quantity increase about 10% more than the preceding year. Although the government have promoted to use recycled coarse aggregate, many registered architects have not use it, because natural aggregate is still cheaper than recycled coarse aggregate's price and they have question about quality of recycled coarse aggregate. In addition, there are no grounds to rely upon compressive strength and ultrasonic pulse velocity method of recycled coarse aggregate when it is used to high strength concrete. In this paper, bases will be adduced to verify applicative possibility of estimation of compressive strength of high-strength concrete with recycled aggregate using ultrasonic pulse velocity method. For this, compressive strength and ultrasonic pulse velocity method tests of 240 high strength concrete specimens with recycled coarse aggregate were performed, and the high strength concrete specimens were tested within the limits such as compressive strength and ultrasonic pulse velocity
Authors: Yong Taeg Lee, Seung Hun Kim, Jong Hyeon Kim, Sang Ki Baek, Young Sang Cho, Seong Uk Hong
Abstract: Recently, many structures which were built about 30 years ago are watched by reconstruction. Demolished concrete is occurred in the process and these quantity increase about 10% more than the preceding year. Fortunately, recycled aggregates are produced from demolished concrete, whereas the recycled aggregates are not used often because there are not many researches which have been verified by experts or researchers about strength when reinforced concrete is made with recycled aggregates. In this paper, high strength reinforced concrete is valued with potential applications and check change of strength when it made by recycled aggregates. For this, flexural tests of 4 high strength reinforced concrete beams with recycled aggregates were performed, and the high strength reinforced concrete beams were tested within the limits such as compressive strength, flexural strength, ductility, strain, and curvature. The current test data were examined in terms of flexural strength, along with the data from previously tested reinforced concrete beams with recycled aggregates.
Authors: Young Sang Cho, Sung Chul Hong, Je Hyuk Lee, Hyun Suk Jang
Abstract: AEC (Architecture, Engineering, and Construction) industries are in the process of paradigm shift on the performance of practice, particularly in the fields of architects, consulting engineers such as structural engineers for structural BIM, civil engineers, MEP engineers, and contractors led by Building Information Modeling (BIM). Overall adoption of BIM in the AEC industries of North America has increased from 17% in 2007 to 71% in 2012 which is over 400% growth over last 5 years. This study analyzes and examines the BIM adoption status of AEC industry in the world including the North America and in the R.O. Korea through the literature survey. This study also examines how academic community is preparing for the drastic cultural change of work process in the construction industry due to BIM adoption in the foreign and domestic AEC industry. This paper presents the case study of BIM education including Capstone Design in the R.O. Korea. This study is to propose that academia needs to establish the appropriate educational curriculum and implementation to enhance, improve and research the state of art BIM technology together with AEC industry.
Authors: Seung Hun Kim, Yong Taeg Lee, T.S. Kim, Soo Yeon Seo, S.K. Baek, Young Sang Cho
Abstract: In this research, the experimental works were conducted to study the lap strength of the headed reinforcements with confinement provided by stirrups or tie-down bars. Five lap splice specimens were tested. Wide beam specimens were fabricated with a lap splice at mid-span. They were loaded in flexure, placing the lap splice in tension. The variables in this study were: confinement details (stirrups, tie-down bars with stirrups) and lap length (10, 14 times the diameter of reinforcement). Specimens were instrumented to measure the load on the specimen, strain along the reinforcements with in the lap zone, and mid-span deflection. The cracking behavior was also observed and recorded. The following conclusions were drawn from the test results in this study; 1) The initial crack of the specimens lapped developed at the heads of reinforcements. The specimens failed by the crack with the struts acting between the opposing heads of lapped reinforcements. 2) Bond stress and confinement details contributed to increase strength and deformation. 3) CCD method evaluated the maximum strength as 4.95∼6.87 times the test maximum strength. The ratios of the test maximum strength and the maximum strength assumed by ACI 318-08 for headed deformed bars were 1.38∼2.01.
Authors: Young Sang Cho
Abstract: A NDT test, spectral analysis of surface wave (SASW) method, is a relatively new technique for examining the structural integrity of structural members of building structures. The SASW method has advantages among NDT methods that it needs an access from only one side of a testing object and can measure the dispersive characteristics in layered structures. This study is to model the wave propagation of stress waves in concrete media using a finite element method. Experiments using the NDT are to be conducted to investigate the wave behavior in concrete media. This study also evaluates the surface wave velocity of single layer cement mortar systems using an experimental analysis of the SASW method, and examines the corresponding results with numerical results. Specimen models were single-layer cement mortar slab systems.
Authors: Seong Uk Hong, Yong Taeg Lee, Seung Hun Kim, Sang Ki Baek, Young Sang Cho
Abstract: This research is to verify and propose the practical use of recycled aggregate concrete which is one of the recycling methods of construction wastes. This is because domestic construction industries have been more sustainably developed, and renovation and redevelopment of buildings for increasing the quality of life have been actively performed because the necessity of efficient management of construction wastes has been increased. In addition, the possibility of increased quality focused on recycled aggregate concrete with mixed polypropylene fiber was proposed on this research through material experiments basedon compressive and split tension strength.
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