• Steel and Composite Structures
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• 제29권1호
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• pp.67-75
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• 2018

High performance concrete (HPC) depends on various parameters such as the type of cement, aggregate and water reducer amount. Generally, the ready concrete company in various regions according to the requirements and costs, mix design of concrete as well as type of cement, aggregates, and, amount of other components will vary as a result of moment decisions or dynamic optimization, though the ideal conditions will be more applicable for the design of mix proportion of concrete. This study aimed to apply dynamic optimization for mix design of HPC; consequently, the objective function, decision variables, input and output variables and constraints are defined and also the proposed dynamic optimization model is validated by experimental results. Results indicate that dynamic optimization objective function can be defined in such a way that the compressive strength or performance of all constraints is simultaneously examined, so changing any of the variables at each step of the process input and output data changes the dynamic of the process which makes concrete mix design formidable.

• 한국디자인학회:학술대회논문집
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• 한국디자인학회 2004년도 추계 학술발표대회 논문집
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• pp.48-49
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• 2004

• 한국도로학회논문집
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• 제19권1호
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• pp.1-9
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• 2017

PURPOSES : The objective of this study is to develop an optimized method of mix design for rapid-set lightweight-formed mortar mix. To achieve this objective, the workability, setting time, and compressive strength of mixes under various conditions of mix design were evaluated. METHODS : The water-bonder ratio, fly-ash substitution ratio, and forming agent injection amount were selected as design variables in the study. The fluidity, setting time, density, and strength of the mortar mix were considered as major evaluation criteria of the mixture, and were subsequently utilized to evaluate the characteristics of the mortar mix under various conditions. RESULTS : The observations made from the mix design process are as follows: 1) the air content and fluidity increase as the forming agent ratio and forming agent ratio increase, respectively; 2) the maximum air content is approximately 20%; 3) the accelerating agent decreases the fluidity of the mortar mix by 15% on average; 4) the forming agent injection ratio and fly-ash substitution ratio yield significant effects on the initial and final set times of the mortar mix; 5) as the forming agent injection ratio and fly-ash substitution ratio increase, the compressive strength of the mortar mix decreases; and 6) the 28-day compressive strengths of the forming agent injection ratio and fly-ash substitution ratio yield the most significant effects. CONCLUSIONS : It is concluded that the governing design variables for the rapid-set lightweight-formed mortar mix are the forming agent injection ratio and fly-ash substitution ratio.

• 콘크리트학회지
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• 제9권2호
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• pp.145-151
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• 1997

콘크리트의 배합설계를 위해서는 각종 콘크리트 표준 시방서의 내용에 대하여 잘 알아야 할 뿐 아니라 현장 경험이 많은 전문가의 경험을 필요로 한다. 그러나 배합 설계에 관련된 모든 인자들과 그 인자들 간의 상호작용에 대하여 모두 고려할 수는 없다. 따라서 적적한 배합설계에 관한 판단은 품질관리를 위한 재료시험을 통하여 판단할 수밖에 없고 그 결과에 따라 보정하는 과정을 거치게 된다. 이렇듯 콘크리트의 배합설계는 재료, 온도, 현장조건, 기술자의 숙련도 등에 대하여는 불확실성이 존재하고 계산과 시험과정에 존재하는 오차로 인하여 엄격한 품질관리를 하여야만 하기 때문에 자칫 지루하며 복잡하고 힘든 일이 될 수밖에 없다. 본 연구에서는 이렇듯 콘크리트의 배합설계 과정에서 나타나는 피할 수 없는 불확실성과 오차들을 최소화하기 위하여 신경망을 적용하였다. 신경망의 학습과 검증을 위한 자료는 콘크리트 표준시방서에 따라 설계기준 강도, 굵은골재 최대치수, 슬럼프, 골재의 조립율 등을 변화시켜 가면서 이론적으로 물-시멘트비, 잔골재율, 단위 수량, 단위 시멘트량, 단위 잔골재량, 단위 굵은 골재량 등을 구하여 사용하였다. 특히 콘크리트의 실제강도는 동일한 조건하에서 강도시험을 실시하여도 결과가 서로 다르게 나타나는 확율변수인점도 고려하였다. 콘크리트의 배합설계에 신경망을 적용한 결과는 그 적용성이 매우 컸다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.457-462
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• 1999

The purpose of this study is to design the requirements for the materials of stabilizing slurry and to determine the optimum slruuy mix design used in the underground wall of Inchon LNG #213 and 214 tank. After the materials and mix conditions of stabilizing slurry investigated and tested, we propose materials and optimum mix design according to testing items including funnel viscosity, we propose materials and optimum mix design according to testing items including funnel viscosity, fluid loss, cake thickness and specific gravity. As this results, we select optimum mix design that the upper limit ratio of bentonite is 2.0%, polymer is 0.1% considering the funnel viscosity and dispersion agent is 0.05% considering the fluid loss. Also we select all materials which are composed of GTC4 as bentonite, KSTP as polymer and Bentocryl as dispersion agent. All test results are satisfied our specifications for stabilizing slurry.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.329-330
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• 2010

구조용 경량콘크리트 배합설계의 전산화를 위하여 ACI211.2-98 (구조용 경량콘크리트 배합설계의 표준 방법)의 배합설계이론을 고찰하고 Jandel사의 Table Curve 2D 및 3D 소프트웨어를 이용하여 그 배합설계과정을 수식화 하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 가을 학술발표회 논문집
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• pp.108-113
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• 1996

Concrete mix degign and adjustments are somewhat complicated and time-consuming tasks in which various uncertainties and errors are involved and depend on the quality control test results. In this paper, as a tool to minimize the uncertainties and errors the neural network is applied to the concrete mix design. Input data to train and test the neural network are obtained from the results of design and adjustments following the concrete standard specifications of Korea. The results show that neural networks have a strong potential as a tool for concrete mix design.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.209-214
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• 1999

Strength provisions in Korea Concrete Institute code are more conservative that those in ACI code by increasing load factors and decreasing capacity reduction factors. Cement content of mix design in construction field is usually higher than the modified for standard deviation because of rigorous inspection. Higher cement content increases not only strengths but also heat of hydration, shrinkage and brittleness which are not beneficial. To reduce and optimize the cement content in current mix design of Korean Highway Corporation, properties of fresh and hardened concrete for 16 different mix proportions have been investigated. It is found that the chemical admixture and cement of current mix proportions for highway construction are somewhat higher than the optimum amount. Therefore, the optimum mix design for 16 different purposes has been proposed.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 추계 학술논문 발표대회
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• pp.101-103
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• 2011

Various desired performances of concrete cannot be always obtained by current conventional mix proportion methods for recycled aggregate concrete (RAC). This paper suggests a new design method of mix proportion for RAC to reduce the number of trial mixes using genetic algorithm (GA) which has been an optimization technique to solve the multi-object problem. In mix design method by GA, several fitness functions for the required properties of concrete, i.e., slump, strength, price, and carbonation speed coefficient were considered based on conventional data or fitness function. As a result, various optimum mix proportions for RAC that meet required performances were obtained and the risk evaluation was also conducted for selected mixtures.

• Computers and Concrete
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• 제3권5호
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• pp.357-373
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• 2006

The concepts of four parameters of nominal water-cement ratio, equivalent water-cement ratio, average paste thickness, fly ash-binder ratio were introduced. It was verified that the four parameters and the mix proportion of mortar can be transformed each other. The behaviors (strength, workability, et al.) of mortar primarily determined by the mix proportion of mortar now depend on the four parameters. The prediction models of strength and workability of mortar were built based on artificial neural networks (ANNs). The calculation models of average paste thickness and equivalent water-cement ratio of mortar can be obtained by the reversal deduction of the two prediction models, respectively. A mortar mix proportion design algorithm was proposed. The proposed mortar mix proportion design algorithm is expected to reduce the number of trial and error, save cost, laborers and time.