• Fire Science and Engineering
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• v.25 no.4
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• pp.103-109
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• 2011

In this study, we calculated the smoke movement at the fire area of the refuge floor which has the refuge safety area in case of fire in the high rise building by using a computational fluid dynamics (CFD) code of FLUENT (ver. 13.0). The buoyancy plume was applied using the temperature and flow velocity which represent 10 MW heat release rate in order to describe the fire, and the smoke movement was predicted using a species conservation equation. The pressurization system of smoke control was adopted with smoke control damper in refuge safety area, at the result, it is confirmed that the damper capacity was enough to smoke control in which the flow rate of supply was applied 25 $m^3/s$ in the case of the door at fire area opened only, and 50 $m^3/s$ in the doors at the fire area and lobby both opened case. They were satisfied in NFSC 501-A. Even though the door of fire area closed, there were smoke leakages at the gap between the door and wall. In addition, the refugee could be isolated in the fire area when the door of fire area closed during smoke control in the case of using the high damper flow rate of supply, 50 $m^3/s$. Therefore the proper damper flow rate of supply are needed in order to prevent the damage of refugee and this study proposes the suitable condition of damper capacity according to refuge scenario.

• Journal of the Korea Institute of Building Construction
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• v.10 no.5
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• pp.113-119
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• 2010

Fire resistance and field tests for high-strength concrete(HSC) of 80MPa were carried out to evaluate whether or not it shows the same material properties even in the field condition of being mass-produced and supplied. As a result, it was found that fire resistant HSCs containing composite fiber(NY, PP) of 0.075% have great resistance to fire and spalling. In the field test, before the pumping air contents, slump flow, U-box, L-flow, compressive strength, gap of hydration temperature of interior and exterior of specimen and placing ratio per hour satisfied the required properties of HSC. However, after the pumping of HSC, as slump flow and L-flow were slightly less than required criterion, they need to be improved. In terms of hydration temperature of HSC, it was found to satisfy the related criterion. Packing ability as well as placing ratio per hour of HSC, which was about $44m^3$, show outstanding results. If slump flow of developed ternary HSC is improved after the pumping it can be useful for the construction of high-rise buildings.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.333-336
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• 2008

As the high-rise building increase due to the gravitation of population to big cities recently, it requires high quality and high performance of Concrete. As a result, people are keenly interested in Meta-kaolin as new admixture favorable from an economic perspective, which has strength and endurance with admixture at the same level like Silicafume. Accordingly, as to Meta-kaolin, this study was to set by three levels like domestic one, foreign one, and Silicafume, the waterbinding material ratio 25%, and four level substitute like 0, 10, 20, and 30(%) in order to compare and analyze the quality characteristics of high-strength concrete according to the substitute of Meta-kaolin applicable with replacement of Silicafume. As a result of performing experiment, as to the higher the additive amount of Superplasticizing agents in order to secure target liquidity was, the more the substitute in each admixture increased. This study had a tendency that the Silicafume increased the additive amount of Superplasticizing agents with high fineness compared with Meta-kaolin. In addition, the higher the substitute in each admixture was, the more its strength increased On the strength property, the higher the substitute in each admixture was, the more its strength increased. This study has found out that the Meta-kaolin has shown the better strength than the one of Silicafume. On the other hand, the relationship between the Compressive strength and Elastic coefficient has shown the similar formula suggested from ACI363.

• Korean Journal of Construction Engineering and Management
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• v.16 no.3
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• pp.68-77
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• 2015

One of recent concerns for super-tall buildings is how to manage hoisting plans and equipment efficiently. Disasters are frequently occurred in relation to electromotive hoists and cranes which are commonly used in construction sites. For construction lifts, particularly, it is highly important to conduct regular inspections or prepare against breakdown in terms of safety. However, unfortunately the reality is that regular inspections are only flatly conducted according to operating hours only. A lift, whose life span is subject to the complicated considerations such as operating hours, loading condition, and the like of each component, is far too invalid as a means of maintenance. As a way to resolve this problem and improve its convenience and safety for users, this study intends to calculate individual inspection interval for the main components of lifts by measuring their actual operating hours with sensing technology and analyzing their historical data. The findings of study include calculation of inspection intervals for the main components of lifts and classification of components to check by the actual operating hours of lift (40, 90, 130, 400 hours), which are drawn up into tables. This will make an opportunity to suggest efficient maintenance measures by enabling prevention of safety accidents and enhancement of safety for workers. Also, it will lead to increasing productivity of works by eliminating sources of delaying the term due to the breakdown of lifts.

• Journal of Korean Society of Steel Construction
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• v.25 no.5
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• pp.569-578
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• 2013

In a super-tall building construction, thick and large-sized embed plates are usually used to connect mega structural steel members to RC core wall or columns by welding a gusset plate on the face of the embed plate with T-shape. A large amount of heat input accumulated by weld passes causes the plates to expand or deform. In addition, the temperature of concrete around the plates also could be increased. Consequently, cracks and spalls occur on the concrete surface. In this study, the effect of weld heat on embed plates and 80MPa high strength concrete is investigated by considering weld position (2G and 3G position), edge distance, concrete curing time, etc. Measured temperature of the embed plates was compared with the transient thermal analysis results. Finally, push-out tests were performed to verify and compare the shear studs capacity of the embed plate with design requirement. Test result shows that the shear capacity of the plate is reduced by 14%-19% due to the weld heat effect and increased as the concrete curing time is longer.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.669-676
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• 2017

Recently, due to the importance of information security, security vulnerability analysis and various information protection technologies and security systems are being introduced as a countermeasure against cyber-attacks in new as well as existing buildings, and information security studies on high-rise buildings are also being conducted. However, security system introduction and research are generally performed from the viewpoint of general IT systems and security policies, so there is little consideration of the infrastructure of the building. In particular, the BAS or building infrastructure, is a closed system, unlike typical IT systems, but has unique structural features that accommodate open functions. Insufficient understanding of these system structures and functions when establishing a building security policy makes the information security policies for the BAS vulnerable and increases the likelihood that all of the components of the building will be exposed to malicious cyber-attacks via the BAS. In this paper, we propose an architecture reference model that integrates three different levels of BAS structure (from?) different vendors. The architectures derived from this study and the security characteristics and vulnerabilities at each level will contribute to the establishment of security policies that reflect the characteristics of the BAS and the improvement of the safety management of buildings.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.6
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• pp.93-99
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• 2020

In terms of construction work, the construction cost is lower than the importance of the construction, and since it is demolished after the completion of the construction, it is treated as a relatively small proportion compared to other construction types. Construction engineers who actually worked on the site talk about the safety of the construction work as the most important work of the various processes to ensure the quality and safety of the construction work. However, it is also true that safety management is difficult for temporary construction because various types of temporary materials are installed at various sites at the same time as construction progresses, and the main construction is carried out using them. Safety accidents in construction work are not much different even if they are carried out in temporary construction. The importance and safety of construction work cannot be neglected in view of the recent trend of large-scale construction, multi-purpose, excavation of large-scale underground spaces, and construction trends that are changing to skyscrapers. The purpose of this research is to secure the safety of Dongbar among the temporary materials used in construction work by using IT convergence technology, and to propose safety management to prevent safety accidents in the construction work.

• Journal of the Korea Concrete Institute
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• v.24 no.3
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• pp.275-283
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• 2012

Steel Plate for Rebar Connection was recently developed to splice rebars in delayed slab-wall joints in high-rise building, slurry wall-slab joints, temporary openings, etc. It consists of several couplers and a thin steel plate with shear key. Cyclic loading tests on slab-wall joints were conducted to verify structural behavior of the joints having Steel Plate for Rebar Connection. For comparison, joints with Rebend Connection and without splices were also tested. The joints with Steel Plate for Rebar Connection showed typical flexural behavior in the sequence of tension re-bar yielding, sufficient flexural deformation, crushing of compression concrete, and compression rebar buckling. However, the joints with Rebend Connection had more bond cracks in slabs faces and spalling in side cover-concrete, even though elastic behavior of the joints was similar to that of the joints with Steel Plate for Re-bar Connection. Consequently, the joints with Rebend Connection had less strengths and deformation capacities than the joints with Steel Plate for Re-bar Connection. In addition, stiffness of the joints with Rebend Connection degraded more rapidly than the other joints as cyclic loads were applied. This may be caused by low elastic modulus of re-straightened rebars and restraightening of kinked bar. For two types of diameters (13mm and 16mm) and two types of grades (SD300 and SD400) of rebars, the joints with Steel Plate for Rebar Connection had higher strength than nominal strength calculated from actual material properties. On the contrary, strengths of the joints with Rebend Connection decreased as bar diameter increased and as grade becames higher. Therefore, Rebend Connection should be used with caution in design and construction.