• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.2
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• pp.9-20
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• 2014

Steel intermediate moment frames (IMFs) have been generally used as seismic load resisting systems (SLRSs) of a building to provide resistances against strong ground shaking. However, most of low and mid-rise steel buildings in Korea were constructed during pre-seismic code era or before the introduction of well-organized current seismic codes. It has been recognized that the seismic performance of these steel IMFs is still questionable. In order to respond to such a question, this study quantitatively investigates the seismic capacities of steel IMFs. Prototype models are built according to the number of stories, the levels of elastic seismic design base shear and the ductilities of structural components. Also, the other prototype models employing hysteretic energy dissipating devices (HEDDs) are considered. The collapse mechanism and the seismic performance of the prototype models are then described based on the results obtained from nonlinear-static and incremental-dynamic analyses. The seismic performance of the prototype models is assessed from collapse margin ratio (CMR) and collapse probability. From the assessment, the prototype model representing new steel IMFs has enough seismic capacities while, the prototype models representing existing steel IMFs provide higher collapse probabilities. From the analytic results of the prototype models retrofitted with HEDDs, the HEDDs enhance the seismic performance and collapse capacity of the existing steel IMFs. This is due to the energy dissipating capacity of the HEDDs and the redistribution of plastic hinges.

• KIEAE Journal
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• v.6 no.2
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• pp.59-66
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• 2006

Green Roof Systems are embossed that realize ecological architecture as a substantially alternative plan. So, a Purpose of the study is seeking to optimize expectation effect through the Green Roof System. we set possible object and propose the prototype on the basis of the existing Green roof System technologies. We visualize a proposed Prototype apply various materials and methods. and we analyse the effects of Green Roof System upon our City climate with use energy efficiency comparison the Green roof system with the Concrete Rooftop. We'll Provide the low data for The prospects of City climate improvement through the a ripple effect on Green Roof System and for activation of Green Roof Technology.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.209-217
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• 2021

This paper investigates the effect of high strength hooked-end steel fiber content and aspect ratio on the compressive and flexural performance of concrete. A total of ten mixtures were prepared and tested. Concretes with specific compressive strength of 30 MPa were reinforced with three different aspect ratios (l/d) of steel fibers 64, 67, and 80 and three different percentages of steel fibers 0.25, 0.50, and 0.75% by volume of concrete. Tensile strengths of steel fibers with l/d of 64, 67, and 80 are 2,000, 2,400, and 2,100 MPa, respectively. The compressive and flexural properties of plain and steel fiber-reinforced concrete (SFRC) mixtures were evaluated and compared. The experimental results indicated that the incorporation of high-strength hooked-end steel fibers had significant effects on the compressive and flexural performance of concrete. With the increase of steel fiber content, compressive performances, such as Poisson's ratio and toughness, of concrete were improved. The steel fibers with the least l/d of 67 resulted in a larger enhancement of compressive performances. The residual flexural strength, that is, post-cracking flexural resistance and toughness, of concrete is mainly depended on the dosage and aspect ratio of steel fibers. The residual flexural strength at serviceability (SLS) and ultimate limit state (ULS) defined in fib Model Code 2010 (MC2010) is increased as the fiber content and aspect ratio increase.

• Journal of the Korean Solar Energy Society
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• v.30 no.5
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• pp.32-37
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• 2010

In order to handle the crisis about energy-environment problem, it is necessary to develop the future-oriented and innovative energy technology in architecture area. So the development of new technology for energy saving and alternative energy use has been spurred in this area. Double skin window system, which is an active covering to respond to the exterior change of the environment, is the skill that can reduce the indoor cooling and heating load and the environmental architecture can be realized. This study works out U-value of windows using the window-simulation program with the development and study of the double skin. In addition, the effect of the double skin insulation on the efficiency rating has been analyzed, applying to the certification system of the building energy efficiency rating which has implemented.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.5
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• pp.89-96
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• 2023

In this study, the displacement dependence, strength, and energy dissipation capacity of the steel rod damper were evaluated. The test variables were cross-sectional shape and aspect ratio. The 6th test specimens were made for performance test. From the test results, it was evaluated that the displacement dependence conditions of design code were satisfied in all specimens. And the strength effect according to the cross-sectional shape was minimal. As a result, the strength and energy dissipation capacity of the aspect ratio of 13.7 were evaluated as excellent.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5284-5289
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• 2011

This study focused to evaluate thermal transmittance(U-value) performance of sliding type of aluminum alloy window frame(AAWF) with double glazing(DG) and glazing spacer and that without thermal breaker in winter and summer season by two dimensional steady state heat transfer analysis. The AAWE was installed to an existing educational facilities in Seosan area which is the southern region of the Korean Peninsula. Analysis of 2D steady-state heat transfer was performed through the use of BISCO as calculation and simulation program. U-value and temperature factors were calculated. The results are as followed. First, the isotherm simulation shows that AAWF with double glazing have serious differences from recently proposed window thermal performance standards such as Insulation Performance of Windows and Doors of Building Energy Saving Design Standards and the results of calculation of thermal transmittance performance of AAWF and DG are U=9.631 W/$m^2K$, U=2.382 W/$m^2K$ respectively during winter and summer season. Second, the results of analysis of heat transfer analysis, calculated by simulation, shows that 225% of heat is lost comparing with thermal performance standards U=4.0 W/$m^2K$ of general double glazing among those standards on AAWF without thermal breaker.

• Korean Journal of Construction Engineering and Management
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• v.18 no.1
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• pp.27-36
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• 2017

Ministry of Land, Infrastructure and Transport established Heating and cooling energy conservation plan of apartment for 2017, reducing 90% compared to energy consumption of 1990. Also, at 2015 United Nations Climate Change Conference, the Ministry announced to reduce 37% of estimated $CO^2$ emission(850 million ton) at 2030. To satisfy this, it is urgent to reduce $CO^2$ emission due to the building, which takes majority amount of total $CO^2$ emission, and public interest for the commissioning of intensified building performance is uprising. However, the building commissioning at construction is not enacted, and not activated due to the lackness of promotion and will of general contractor. Furthermore, commissioning is not mandatory for obtaining G-SEED certification. Therefore, this paper describes effectiveness of commissioning with comparison of commissioning evaluation criteria of G-SEED with LEED and BREEAM, to propose making commissioning as mandatory process and drive changes in perception among stakeholders for activation of domestic building commissioning.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.4
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• pp.347-355
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• 2021

During the earthquake, for multi-story structure, if the first floor is soft, the deformation will concentrate on that floor causing a serious damage to the column members which might leads to the collapse of the whole structure like Piloti structure during the Pohang earthquake in Korea. According to the 2016 National Disaster Management Research Institute's "Investigation of Seismic Reinforcement and Cost Analysis of Domestic Non-seismic Buildings", the rate of seismic resistance of private reinforced concrete buildings was 38.3 %. Among them, it was reported that the seismic-resistance ratio of the two to five-story structures was less than 50 %. Accordingly, the government is trying to improve the seismic rate through support projects, but the conventional seismic reinforcement methods are still expensive, and emergency construction is difficult. Therefore, in this study, the field applicability was evaluated by improving the reinforcement method using Velcro, which was developed through the research project of the Ministry of Land, Transport and Maritime Affairs in 2014. In order to improve the performance of the Velcro reinforcement method, introducing the initial tension of Velcro using high foaming rigid urethane filling between the Velcro and concrete of the columns was applied. Additionally, an experiment was conducted to evaluate the ductility of Velcro specimen from the concrete confinement effect. As a result, the ductility of the Velcro specimen was improved compare to Normal specimen. However, the energy dissipation capacity of VELCRO2 is better than VELCRO1, yet the maximum ductility of those two specimens did not show a significant difference. Therefore, the improvement of the internal filler material is still needed to have a better maximum ductility.

• Resources Recycling
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• v.28 no.1
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• pp.32-39
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• 2019

The present study investigated hydration of alkali activated slag incorporating sulfate as a form of anhydrite by employing thermodynamic modeling using the Gibbs free energy minimization approach. Various parameters were evaluated in the thermodynamic calculations, such as presence of sulfide, precipitation/dissolution of AFt/AFm phase, and the effect of oxic condition on the predicted reaction. The calculations suggested no significant difference in the void volume and chemical shrinkage, which might influence the performance of the mixtures, in spite of various changes of the parameters. Although the types of hydration products and their amount varied according to the input conditions, their variations were smaller range than that induced by water-to-binder ratio. Moreover, it did not affect the amount of C-(N-)A-S-H which was the most important hydration product.

• Journal of Korean Society of Steel Construction
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• v.22 no.1
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• pp.43-53
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• 2010

Seismic isolation is one of the most widely implemented and accepted seismic protection systems to limit or avoid damages from unforeseeable earthquakes. As an energy absorption device, however, the supplemental lead itself tends to pollute the environment. Consequently, it is predicted that the use of lead would be controlled. Considering the pollution caused by lead, several researchers are interested in the viability of using steel in place of lead. In this study, first, based on the results of a non-linear finite element analysis, the excellent deformation capacity of a very tough steel damper was demonstrated by comparing it with that of the SS400 damper and determining the effects of main parameters (the aspect ratio, thickness, and width) on the deformation capacity. Second, an optimum shape and design equation for a U-shaped damper with an opening based on stress distribution was suggested.