• Smart Structures and Systems
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• v.26 no.2
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• pp.241-251
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• 2020

Due to the undeniable importance of approximating the concrete compressive strength (CSC) in civil engineering, this paper focuses on presenting four novel optimizations of multi-layer perceptron (MLP) neural network, namely artificial bee colony (ABC-MLP), grasshopper optimization algorithm (GOA-MLP), shuffled frog leaping algorithm (SFLA-MLP), and salp swarm algorithm (SSA-MLP) for predicting this crucial parameter. The used dataset consists of 103 rows of information concerning seven influential parameters (cement, slag, water, fly ash, superplasticizer, fine aggregate, and coarse aggregate). In this work, the best-fitted complexity of each ensemble is determined by a population-based sensitivity analysis. The GOA distinguished its self by the least complexity (population size = 50) and emerged as the second time-effective optimizer. Referring to the prediction results, all tested algorithms are able to construct reliable networks. However, the SSA (Correlation = 0.9652 and Error = 1.3939) and GOA (Correlation = 0.9629 and Error = 1.3922) performed more accurately than ABC (Correlation = 0.7060 and Error = 4.0161) and SFLA (Correlation = 0.8890 and Error = 2.5480). Therefore, the SSA-MLP and GOA-MLP can be promising alternatives to laboratorial and traditional CSC evaluative methods.

• Journal of Environmental Science International
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• v.19 no.5
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• pp.639-646
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• 2010

Differently from fly ash, the bottom ash produced from incinerated urban solid waste has been treated as an industrial waste matter, and almost reclaimed a tract form the sea. If this waste material is applicable to foam concrete as an fine aggregate, however, it may be worthy of environmental preservation by recycling of waste material as well as reducing self-weight of high-rising structure and long-span bridge. This research has an objective of evaluating the effects of application of bottom ash on the mechanical properties of foam concrete. Thus, the ratio of bottom ash to cement was selected as a variable for experiment and the effect was tested by compression strength, flexural strength, absorption ratio, density, expansion factor. It can be observed from experiments that the application ratios have different effects on the material parameters considered in this experiment, thus major relationship between application ratio and each material parameter were finally introduced. The result of this study can be applied to decide a optimal mix design proportion of foam light-weight concrete while bottom ash is used as an fine aggregate of the concrete.

• Structural Engineering and Mechanics
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• v.53 no.5
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• pp.921-938
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• 2015

Realistic prediction of concrete creep is of crucial importance for durability and long-term serviceability of concrete structures. To date, research about the behaviour of self-compacting concrete (SCC) members, especially concerning the long-term performance, is rather limited. SCC is quite different from conventional concrete (CC) in mixture proportions and applied materials, particularly in the presence of aggregate which is limited. Hence, the realistic prediction of creep strains in SCC is an important requirement for the design process of this type of concrete structures. This study reviews the accuracy of the conventional concrete (CC) creep prediction models proposed by the international codes of practice, including: CEB-FIP (1990), ACI 209R (1997), Eurocode 2 (2001), JSCE (2002), AASHTO (2004), AASHTO (2007), AS 3600 (2009). Also, SCC creep prediction models proposed by Poppe and De Schutter (2005), Larson (2007) and Cordoba (2007) are reviewed. Further, new creep prediction model based on the comprehensive analysis on both of the available models i.e. the CC and the SCC is proposed. The predicted creep strains are compared with the actual measured creep strains in 55 mixtures of SCC and 16 mixtures of CC.

• Computers and Concrete
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• v.3 no.4
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• pp.249-260
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• 2006

Self-consolidating concrete (SCC) in the fresh state is known for its excellent deformability, high resistance to segregation, and use, without applying vibration, in congested reinforced concrete structures characterized by difficult casting conditions. Such a concrete can be obtained by incorporating either mineral or chemical admixtures. This paper presents the results of an investigation to asses the applicability of Abram's law in predicting the compressive strength of SCC to any given age. Abram's law is based on the assumption that the strength of concrete with a specific type of aggregate at given age cured at a prescribed temperature depends primarily on the water-to-cement ratio (W/C). It is doubtful that such W/C law is applicable to concrete mixes with mineral or chemical admixtures as is the case for SCC where water to binder ratio (W/B) is used instead of W/C as the basis for mix design. Strength data of various types of SCC mixtures is collected from different sources to check the performance of Abram's law. An attempt has been made to generalize Abram's law by using various optimization methodologies on collected strength data of various SCC mixtures. A set of generalized equations is developed for the prediction of SCC strength at various ages. The performance of generalized equations is found better than original Abram's equations.

• Computers and Concrete
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• v.20 no.4
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• pp.461-468
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• 2017

With the increasing demand in the production of concrete, there is a need for adopting a feasible, economical and sustainable technique to fulfill practical requirements. Self-Compacting Concrete (SCC) is one such technique which addresses the concrete industry in providing eco-friendly and cost effective concrete. The objective of the present study is to develop a mix design for SCC with Crushed Rock Fines (CRF) as fine aggregate based on the plastic viscosity of the mix and validate the same for its fresh and hardened properties. Effect of plastic viscosity on the fresh and hardened properties of SCC is also addressed in the present study. SCC mixes are made with binary and ternary blends of Fly Ash (FA) and Ground Granulated Blast Slag (GGBS) with varying percentages as a partial replacement to Ordinary Portland Cement (OPC). The proposed mix design is validated successfully with the experimental investigations. The results obtained, indicated that the fresh properties are best achieved for SCC mix with ternary blend followed by binary blend with GGBS, Fly Ash and mix with pure OPC. It is also observed that the replacement of sand with 100% CRF resulted in a workable and cohesive mix.

• Journal of the Korean Society of Clothing and Textiles
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• v.35 no.11
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• pp.1333-1345
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• 2011

This study establishes public self-consciousness, sociocultural attitudes toward appearance, and objectified body consciousness as causal variables to identify their direct or indirect effects. This study is an aggregate analysis of existing studies that reveals the relations of how these factors turn to be the image management behaviors. A survey was conducted on 962 women from the ages of 20 to 59 who live in the Daegu and Gyeongbuk areas. The data analysis was performed through programs such as AMOS 16.0 and SPSS 18.0 for Windows. The findings are as follows: first, public self-consciousness had a direct effect on the sociocultural attitudes toward appearance and on objectified body consciousness, whereas it affected image management behaviors directly or indirectly. This means that as women become aware of others' attention, they recognize the social importance of appearance, internalize ideal social standards, and observe and evaluate their own bodies from a third person's viewpoint regarding the standards for a body required by society; in addition, these procedures lead them to manage their image behaviors. Second, the sociocultural attitudes toward appearance had a direct influence on objectified body consciousness; however, they had an indirect effect on image management behaviors. This demonstrates that body consciousness plays a role as a mediator between the sociocultural attitudes toward appearance and the image management behaviors. Third, it appeared that objectified body consciousness directly affected image management behaviors. Objectified body consciousness was identified as a causal variable that exerts immediate influence on image management behaviors where the more objectified body consciousness women objectified themselves as the body standards that created further image management behaviors.

• Bulletin of the Korean Chemical Society
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• v.25 no.2
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• pp.298-300
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• 2004

An alternative molecular porphyrin-phthalocyanine aggregate was prepared and characterized with UV-visible and X-ray absorption spectroscopies. UV-visible experiments evidence 1-dimensional porphyrin-phthalo-cyanine array formed by mixing $SnTPPCl_2 ({\lambda}_{max}=429,\;{\varepsilon}=2.4{\times10^ 5 /M{\cdot}cm)\;and\;NiPc(OBu)_8({\lambda}_{max}=744 nm,\;{\varepsilon}= 2.0{\times}10^ 5 /M{\cdot}cm)$ in solution. In the UV-visible spectrum of the porphyrin-phthalocyanine array, $(SnPNiPc)_n$, a new Q-band appeared at 844 nm with decrease of the Q-band peak of $NiPc(OBu)_8$ at 744 nm. The red-shift of Q-band evidences an alternative porphyrin-phthalocyanine array formed in solution through metal-halide interaction rather than ${\pi}-{\pi}$ facial interaction, in which nickel of $NiPc(OBu)_8$ coordinates with chloride of $SnTPPCl_2$ through self assembly. Ni K-edge XANES (X-ray absorption near edge structure) spectra also support the axial ligation of nickel to chloride. The square planar structure of $NiPc(OBu)_8$ turns to an octahedral structure in (SnPNiPcSnP) by axial ligation. A higher energy-shift (0.2 eV) of the preedge peak of (SnPNiPcSnP) indicaties partial oxidation of nickel by charge transfer from NiPc$(OBu)_8$ to SnTPPCl$_2$.

• Restorative Dentistry and Endodontics
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• v.45 no.1
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• pp.10.1-10.8
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• 2020

Objectives: This study aimed to compare the shear bond strength (SBS) of a self-adhering flowable composite (Dyad Flow) and a bulk-fill flowable composite (Smart Dentin Replacement [SDR]) to several pulp-capping materials, including MTA Plus, Dycal, Biodentine, and TheraCal. Materials and Methods: Eighty acrylic blocks with 2-mm-deep central holes that were 4 mm in diameter were prepared and divided into 2 groups (n = 40 each) according to the composite used (Dyad Flow or SDR). They were further divided into 4 sub-groups (n = 10 each) according to the pulp-capping agent used. SBS was tested using a universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed using 2-way analysis of variance. A p value of < 0.05 was considered to indicate statistical significance. Results: A statistically significant difference (p = 0.040) was found between Dyad Flow and SDR in terms of bond strength to MTA Plus, Dycal, Biodentine, and TheraCal. Conclusions: Among the 8 sub-groups, the combination of TheraCal and SDR exhibited the highest SBS.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.287-292
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• 2002

In the 1970's, the environmental preservation is out of public issue, caused by rapid economic growth and industrialization. When the people's living standard Is grows, they aware of the environmental importance. In modern times, the environment preservation is global tendency and self social awareness is arise. Measures to the environment preservation and pollution is going on study. One measure is recycling and reuse of by product and it is already developed in some advanced country. But, the study about by product reuse is just beginning in domestic. The purpose of this study is reusing copper slag by product which produced in the copper refining process-as fine aggregate for developing high strength concrete. Concrete nix and properties, the result of mock up test for site application are analyzed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2002.05a
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• pp.97-102
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• 2002

The ability to pass between bars is one of the most important performance of self-compacting concrete or high-flowability concrete since it determines the final filling capacity which influences the strength and durability of hardened concrete in structure. Therefore it has been evaluated by many researchers using different kinds of testing apparatuses. The assessments of passing ability, however, differ largely according to the style, the dimension and the criteria in apparatuses, and the value obtained from one apparatus cannot be converted those of the others. There needs a rheological approach to the better understanding of the passing behavior of fresh concrete between reinforcing bars, where the flow velocity of concrete becomes slow and the blockade sometimes occurs due to the interference between aggregates and reinforcing bars. Experimental works were conducted to clarity the effects of the clearance between reinforcing bars, the volume of aggregate and the rheological properties of matrix on the behavior from the rheological point view and showed the rational mix proportioning of concrete.