• Computers and Concrete
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• v.24 no.4
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• pp.295-302
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• 2019

Evolutionary algorithms based on conventional statistical methods such as regression and classification have been widely used in data mining applications. This work involves application of gene expression programming (GEP) for predicting compressive strength of fly ash geopolymer concrete, which is gaining increasing interest as an environmentally friendly alternative of Portland cement concrete. Based on 56 test results from the existing literature, a model was obtained relating the compressive strength of fly ash geopolymer concrete with the significantly influencing mix design parameters. The predictions of the model in training and validation were evaluated. The coefficient of determination ($R^2$), mean (${\mu}$) and standard deviation (${\sigma}$) were 0.89, 1.0 and 0.12 respectively, for the training set, and 0.89, 0.99 and 0.13 respectively, for the validation set. The error of prediction by the model was also evaluated and found to be very low. This indicates that the predictions of GEP model are in close agreement with the experimental results suggesting this as a promising method for compressive strength prediction of fly ash geopolymer concrete.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1065-1068
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• 2008

Concrete is still one most common construction materials even in railway structures. As structures become massive and mega-sized, the importance of early age concrete quality control becomes more significant. Among various factors, relative humidity and temperature are the primary factors governing the early age quality. Temperature raise due to cement hydration causes stress, which can develop to cracking with internal and/or external restraints. Exposure conditions including ambient temperature, humidity and wind also significantly affect the cracking behavior of early age concrete. Among many of studies on the early age concrete behavior, investigation on the variation of temperature and relative humidity internal of concrete is not common. That is in part because the difficulties in measuring the relative humidity and temperature inside the concrete. This study used a digital sensor with an appropriate logger to measure internal temperature and relative humidity. This direct measuring method is expected to provide more reliable and comprehensive data acquisition on the early age behavior of concrete.

• PNF and Movement
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• v.11 no.1
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• pp.35-42
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• 2013

Purpose : This paper reviews intensity of physical therapy for stroke. Methods : This is literature study with Pubmed, EBSCO, ProQuest, EMBASE and CINAHL. Results : There were 20 studies that reviewed effects of increased intensity of physical therapy after stroke involving time post-stroke, elements of physical therapy, duration of physical therapy, methods of physical therapy. Ten of the eleven studies, involving time post-stroke, demonstrated significant improvement. Seventeen studies involving upper extremity, lower extremity and mobility demonstrated significant improvement. Five studies involving increased duration of physical therapy demonstrated significant improvement. Studies involving methods of physical therapy showed that mix of different methods is more effective than single method. Conclusion : Increased intensity of physical therapy improve functional recovery.

• Journal of East-West Nursing Research
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• v.16 no.2
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• pp.85-95
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• 2010

Purpose: This study aimed to identify major trends and characteristics of studies on aromatherapy in Korea. Methods: Literature on the studies of aromatherapy in Korea was retrieved using RISS, KISS, DBpia, and Pubmed. The studies were analyzed based on publication year, study design, intervention method, and measuring variables. The level of applied intervention was assessed by target group, the types of aroma, and their effects. Results: A total of 111 studies was included in this study. Most of studies on aromatherapy were conducted using a experimental design to test the effects of aromatherapy as a nursing interventions. Conclusion: This study showed that methods of mixing oils, sites of massage, and target groups vary among studies on aromatherapy in Korea. It is suggestive that standardized methods to mix oils and to apply aroma is in need.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.197-198
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• 2020

A study was conducted on UHPC production using the silicone mold method. UHPC (Ultra-High-Performance Concrete) has the advantage of being able to shape the product in a free-form shape on concrete, but when mass-producing products in one design, such as electronic products, rather than one-time products such as buildings and decorations Demolition is difficult with wood and mold. This study uses silicone molds, UHPC mix to ensure fluidity, self-integrating performance and mechanical performance Prototyping was done proportionally.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.142-143
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• 2020

A study was conducted on the production of LEFC using the Precast method, not the on-site construction. LEFC, Light Emotion Friendly Concrete, has the advantage of plastic rods being inserted to allow light to transmit, but because of the lack of adhesion to concrete, it leads to a decline in mechanical performance and durability. Therefore, it is necessary to apply precasting techniques to ensure homogeneous and superior quality of LEFC. In this study, wooden molds were used and plastic rods were arranged on porous acrylic plates. Prototyping was carried out with a UHPC mix proportioning to ensure flowability, self-consolidating performance and mechanical performance.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.113-114
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• 2022

The aim of the research is to evaluate the segregation resistivity of the mixture conditions by changing the PVA and borax solutions for thixotropic property on concrete mixture. Since the water addition caused by producing solutions of PVA and borax induces segregation of the concrete mixture, the unit water was reduced by replacing the water amount for PVA and borax solution. By replacing the water from PVA and borax solutions, the segregation was prevented with prefixed concrete mix design and thixotropic properties were also occurred.

• Journal of the Korea Concrete Institute
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• v.22 no.2
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• pp.171-177
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• 2010

Recently, Performance Based Design (PBD) method has been studied as a next generation structural design method, which enables a designed structure to satisfy the required performance during its service life. One method of deciding whether the required performance has been satisfied is Bayesian method, which has been commonly used in seismic analysis. Generally, it is presented as a conditional probability of exceeding some limit state (i.e., collapse) for a given ground motion. In PBD of concrete mixture design, the same methodology can be applied to assess concrete material performance based on some conditional parameters (i.e. strength, workability, carbonation, etc). In this paper, a detailed explanation of the procedure of drawing satisfaction curve by using Bayesian method based on various material parameters is shown. Also, a discussion of using the developed satisfaction curves for PBD for concrete mixture design is presented.

• Journal of the Society of Disaster Information
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• v.8 no.1
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• pp.27-35
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• 2012

The main objective of this paper is to evaluate the field applications and the noise reductions of micro surfacing pavement, which is often used to reduce environmental problems. A traffic noise mechanism was analyzed and a modified mix design method was proposed for nighttime constructions. Results on noise measurements using the statistical pass-by method showed noise reductions of 2.0 to 7.1 dB were observed. In addition, results on noise measurements using the close proximity method demonstrated that noise reductions of 5.6 to 6.7 dB were recorded under vehicle speed of 80km/h. The noise measurements revealed that the close proximity method was more stable than the statistical pass-by method. As a result, the effect of micro surfacing pavement on noise reductions was proved through the research. It is considered that the micro surfacing pavement method could be used as a preventive maintenance method and a comfortable noise reducing pavement technique.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.75-81
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• 2010

In this study, when concrete properties are changed by concrete mix proportions or blending of admixtures, the characteristics of electro-chemical method for corrosion assessment of the embedded steel are compared and its causes are analyzed. According to the results, when the ratio of corroding area was less than 10%, the half-cell method was affected by concrete properties. In the case of specimen blended admixtures, it is possible to assess the high-corroded steel qualitatively using the half-cell method. For the polarization resistance method, though the corroding area was less than 10%, it has not affected by concrete properties. However, in case of specimen blended admixtures, the corrosion level of steel was underestimated than OPC specimens having a similar corroding area.