• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.1036-1044
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• 2023

The combination of MCNP6 and the FISPACT codes was used to predict inventories of radioisotopes produced by neutron exposure of a sample in a research reactor. The detailed MCNP6 model of the Budapest Research Reactor and the specific irradiation geometry of the NAA channel was established, while realistic material cards were specified based on concentrations measured by PGAA and NAA, considering the precursor elements of all significant radioisotopes. The energy- and spatial distributions of the neutron field calculated by MCNP6 were transferred to FISPACT, and the resulting activities were validated against those measured using neutron-irradiated small and bulky targets. This approach is general enough to handle different target materials, shapes, and irradiation conditions. A general agreement within 10% has been achieved. Moreover, the method can also be made applicable to predict the activation properties of the near-vessel concrete of existing nuclear installations or assist in the optimal construction of new nuclear power plant units.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.343-344
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• 2010

This study compares the apparent activation energy(Ea) by ASTM C 1074 with that by setting time. As the result of this study, it is found that Ea by setting time was ranged from 15~21 KJ/mol. This value is smaller than that 30~50 KJ/mol by ASTM C 1074.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.477-480
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• 2005

The discharge of sewage sludge is rapidly increasing in Korea. But the most common sewage sludge disposal alternative is to incinerate and to deposit it in controlled landfills. However, space limitations on existing landfill sites, and increasing environmental concerns have prompted the investigation of alternative ash disposal routes. The utilization of sewage sludge ash would contribute to the elimination of an environmental problem and to the development of new high-performance materials. The purpose of this study is to apply to Alkali Activation into solidification of sewage sludge ash. It achieves leaching test, chemical composition and compressive strength test. As a result of tests, the sewage sludge ash has sufficient potential for use of pozzolanic raw material. However, it is judge to be available to construction material if research is continuously gone.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.137-138
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• 2013

Nowadays, research about using recycled aggregate as alkali activator has been investigated. By the mechanism of Alkali activation, blast furnace slag's potential hydraulis property would be activated. Thee application of this technique is considered as fit for low strength concrete, so it's suitable in concrete secondary production such as bricks and blocks. Aside alkali activator, sulfate could also activate blast furnace slag's potential hydranlis property. In this research, gypsum(CaSO4·2H2O)has been added with blast furnace slag. Fundamental experiment such as flow and strength has been tested to evalnate effect of gypsum's activation property.

• Steel and Composite Structures
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• v.42 no.4
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• pp.459-475
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• 2022

In this paper a model for the prediction of the ultimate axial compressive capacity of square and rectangular Concrete Filled Steel Tubes, based on an Artificial Neural Network modeling procedure is presented. The model is trained and tested using an experimental database, compiled for this reason from the literature that amounts to 1193 specimens, including long, thin-walled and high-strength ones. The proposed model was selected as the optimum from a plethora of alternatives, employing different activation functions in the context of Artificial Neural Network technique. The performance of the developed model was compared against existing methodologies from design codes and from proposals in the literature, employing several performance indices. It was found that the proposed model achieves remarkably improved predictions of the ultimate axial load.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.149-150
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• 2023

This study proposes the most suitable strength prediction model equation for UHPC by calculating the apparent activation energy of UHPC according to the curing temperature and deriving the integrated temperature and compressive strength prediction equation. The results are summarized as follows. The apparent activation energy was calculated using the Arrhenius function, which was calculated as 21.09 KJ/mol. A model equation suitable for UHPC was calculated, and when the Flowman model equation was used, it was confirmed that it was suitable for the properties of UHPC using a condensation promoting super plasticizing agent.

• Advances in concrete construction
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• v.5 no.3
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• pp.241-255
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• 2017

Concrete is known to be the most used construction material worldwide. The environmental and economic aspects of Ordinary Portland Cement (OPC) containing concrete have led research studies to investigate the possibility of incorporating supplementary cementitious materials (SCMs) in concrete. Metakaolin (MK) is one SCM with high pozzolanic reactivity generated throughout the thermal activation of high purity kaolinite clay at a temperature ranging from $500^{\circ}C$ to $800^{\circ}C$. Although many studies have evaluated the effect of MK on mechanical properties of concrete and have reported positive effects, limited articles are considering the effect of MK on durability properties of concrete. Considering the lifetime assessment of concrete structures, the durability of concrete has become of particular interest recently. In the present work, the influences of MK on mechanical and durability properties of concrete mixtures are evaluated. Various experiments such as slump flow test, compressive strength, water permeability, freeze and thaw cycles, rapid chloride penetration and surface resistivity tests were carried out to determine mechanical and durability properties of concretes. Concretes made with the incorporation of MK revealed better mechanical and durability properties compared to control concretes due to combined pozzolanic reactivity and the filler effect of MK.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.34-35
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• 2015

The purpose of this study is to investigate the compressive strength property of concrete with Ground granulated blast furnace slag(GBFS) using wash water from recycled aggregate. When GBFS is reacted with water, it doesn't happen to hydraulic reaction but GBFS becomes latent hydraulic property in alkaline environment. For this reason, if it is possible to use wash water from recycled coarse aggregate as mixture water, GBFS have the advantage of early strength due to effect of activation. We investigated the compressive strength properties of GBFS concrete using wash water from recycled aggregate. According to the experimentation result, ICP-OES showed wash water from recycled coarse aggregate has a high alkali value of pH of 12. Also, compressive strength in early age using wash water can be improved as an activation.

• International Commerce and Information Review
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• v.7 no.1
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• pp.283-307
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• 2005

The research was carried out at the electronic Gw-mart located at Gangwon province. The secondary data and the various other reference materials were used for the research. This research brings forth the concrete activation plan for the activation of an electronic market in the Gangwon province. So, the activation plan for an e-market at Gang won can be done in six ways, first result of the undertaken research achieved in six ways- first, concentration has to be laid on the internet portal sites, second, the local sites should be well connected with the shopping mall facilities, third, a trustworthy shopping mall has to be established by maintains the product quality and quantity, fourth, a visible distinction should be made between the various products, fifth, the division of labor must be specified and a provisions should be made for a efficient after service.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.27-32
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• 2002

In this research influences of type and concentration of alkali activator and curing condition on the hydration, and properties of alkali activated blast furnace slag(AAS) concrete were investigated. Sodium carbonate and sulfate were used as alkali activators and their concentration were 4~10 weight percent with Na$_2$O equivalent to binder. The curing conditions were standard curing using 23$^{\circ}C$ water and activated curing chamber at $65^{\circ}C$. Results show that in case of sodium carbonate addition high early strengths were gained by activation of early hydration, but later strength gained was slight. On the other side sodium sulfate strengths were continuously increased with adding amount and ages. Steam curing activated early hydration so that early strengths were improved but later strengths were similar to standard curing. The strength reduction of AAS mortar with sodium sulfate was less than OPC mortar in 5% sulfuric acid solution so that AAS concrete can be useful for acid-resistance concrete.