• 콘크리트학회지
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• 제26권5호
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• pp.23-28
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• 2014

• 한국건설관리학회논문집
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• 제16권5호
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• pp.97-104
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• 2015

공동주택에 대하여, 2000년 이후 건설한 대상 실적 중 25개 현장에 골조. 미장, 내장, 설비, 전기 통신, 기타의 공종별로 구분하여 월별 노무량의 투입실적의 자료를 수집하였다. 이를 100%기간으로 표준화 된 공기로 변환하여 공종별로 구분하여 노무량 비율로 환산하여 노무비율의 흐름을 분석한 결과 다음과 같이 결론을 도출하였다. (1) 노무비율의 크기는 골조공사 38.25%, 미장공사 5.10%, 내장공사 5.67%, 기계설비공사 9.10%, 전기 통신공사 8.76%, 기타공사 33.12%로 골조공사가 가장 크다. (2) 노무비율이 투입 되는 피크 시기는 52.5%월부터 62.5%월까지이고 3.6%의 노무비율이었다. (3). %월별로 골조공사가 가장 큰 시기는 35%월이고 이때 %월당 2.12% 투입 노무비율이었다. 골조공사가 마무리가 시작되는 65%월부터 80%월에 서로 다른 공종간의 상호 간섭이 가장 큰 시기였다. 본 연구의 결과는 공동주택 건설공사에서 공종별로 가장 큰 혼잡도가 높은 시기를 알려주고 있으며, 이 시기의 집중 공정관리 하는 것이 성공적인 프로젝트 수행에 필수적인 사항이 된다.

• 콘크리트학회논문집
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• 제11권4호
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• pp.21-29
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• 1999

In this study, an experiment was performed to analyze the influence of water-cement ratio on the fundamental characteristics of antiwashout underwater concrete using blended sand (sea sand:river sand = 1:1). The water-cement ratio (45%, 50%, 55%, 60%), andtiwashout underwater agent contents (0.82%, 1.00%, 1.14% of water contents per unit volume of concrete), and superplasticizer contents (1.5%, 2.0%, 2.5% of cement contents per unit volume of concrete) were chosen as the experimental parameters. The experimental results show that the underwater segregation resistance, unit weight of hardening concrete and compressive strength were increased as the water-cement ratio decreased and as the antiwashout underwater agent contents increased. On the other hand, the flowability(slump flow) was increased to the 55% of the increase of water-cement ratio, however, it was decreased at the ratio of 60%. From this study, the antiwashout underwater concrete can potentially be used as a materials underwater work of ocean if the water-cement ratio and chemical admixture contents for the suitable balance between cost and performance are properly selected.

• Computers and Concrete
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• 제32권3호
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• pp.263-286
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• 2023

Experimenting with concrete to determine its compressive and tensile strengths is a laborious and time-consuming operation that requires a lot of attention to detail. Researchers from all around the world have spent the better part of the last several decades attempting to use machine learning algorithms to make accurate predictions about the technical qualities of various kinds of concrete. The research that is currently available on estimating the strength of concrete draws attention to the applicability and precision of the various machine learning techniques. This article provides a summary of the research that has previously been conducted on estimating the strength of concrete by making use of a variety of different machine learning methods. In this work, a classification of the existing body of research literature is presented, with the classification being based on the machine learning technique used by the researchers. The present review work will open the horizon for the researchers working on the machine learning based prediction of the compressive strength of concrete by providing the recommendations and benefits and drawbacks associated with each model as determining the compressive strength of concrete practically is a laborious and time-consuming task.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 봄 학술발표회 논문집
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• pp.48-53
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• 1995

Recently, work of construction industry is not enough to do in tamping because of a lack of expert, advanced-age of worker, increase of structure of high-dengity arrangment and machanization of concrete pumping method Accordingly it is required for high-qualuily concrete with excellent flowability, Self-placeability and regregation registance. In this point of view, this study is investigated for requiremend properties of ultar-flow concrete using dimestic material as for development of Ultra-Flow concrete in the side of material

• International Journal of Concrete Structures and Materials
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• 제10권2호
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• pp.163-175
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• 2016

This paper presents a revised procedure for computation of double-K fracture parameters of concrete split-tension cube specimen using weight function of the centrally cracked plate of finite strip with a finite width. This is an improvement over the previous work of the authors in which the determination of double-K fracture parameters of concrete for split-tension cube test using weight function of the centrally cracked plate of infinite strip with a finite width was presented. In a recent research, it was pointed out that there are great differences between a finite strip and an infinite strip regarding their weight function and the solution of infinite strip can be utilized in the split-tension specimens when the notch size is very small. In the present work, improved version of LEFM formulas for stress intensity factor, crack mouth opening displacement and crack opening displacement profile presented in the recent research work are incorporated. The results of the double-K fracture parameters obtained using revised procedure and the previous work of the authors is compared. The double-K fracture parameters of split-tension cube specimen are also compared with those obtained for standard three point bend test specimen. The input data required for determining double-K fracture parameters for both the specimen geometries for laboratory size specimens are obtained using well known version of the Fictitious Crack Model.

• 대한토목학회논문집
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• 제26권6D호
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• pp.985-993
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• 2006

건설현장에서 기성 콘크리트 파일의 사용이 점차적으로 증가하고 있다. 파일기초를 형성하는 주요 작업들 중의 하나가 콘크리트 파일의 두부를 $800kg/cm^2$ 이상의 압력으로 파쇄하는 것이다. 일반적으로 파일 두부정리 작업은 크러셔와 3~4명의 숙련공에 의하여 실시된다. 최근 파일 두부정리에 관한 보고에 의하면 파일의 강도를 상당히 감소시키는 균열이 작업 중에 많이 발생하고 있고 파일 두부정리 작업이 매우 반복적이고 노동집약적인 것으로 나타났다. 기존의 파일 두부정리 작업의 생산성, 안전성, 품질을 향상시키기 위하여 두부정리 자동화 장비를 개발하기 위한 연구가 진행되고 있다. 본 논문에서는 두부정리선을 인식하기 위한 센싱방법과 작동 프로세스 알고리즘을 제시하고 있다. 이것은 두부정리 자동화 장비를 개발하기 위하여 매우 중요하다. 제안된 센싱방법 중 1가지를 적용한 파일롯 타입의 두부정리 자동화 장비를 개발하였으며, 현장에서 기능을 실험하였다.

• International Journal of Concrete Structures and Materials
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• 제4권1호
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• pp.45-49
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• 2010

The roller compacted concrete (RCC) is supposed to be isotropic, whereas the compaction of this material, which is achieved using the same machines used for the soil, appears only unidirectional, making the RCC an anisotropic material. In this experimental work, the influence of the phenomenon of compaction on the isotropy of the RCC is studied. This study was carried out through an evaluation of the compressive strengths and ultrasonic tests which were used for measurements of the elastic modulus and the dynamic Poisson's ratio of the RCC as well as a qualitative judgement of the RCC aspect at the hardened state. The results of this work proved the anisotropy of the RCC and they showed the sensitivity of the mechanical strengths and the elastic modulus to the compaction direction.

• 한국농공학회지
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• 제42권1호
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• pp.83-91
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• 2000

The purpose of this study is to estimate quantitatively lateral pressure of super-workable fresh concrete applied to form-work of prototype structures, such as tall wall, retaining wall and beam. As a result of this experiment, a function applicable to design a form work system and to predict lateral pressure curve is formulated . Super-workable concrete may be used for the structures reinforced with dense re-bar like box culvert to place concrete at a time, and this study for lateral pressure of super-workable concrete may be useful for form design.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.266-267
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• 2017

As apartment buildings defect lawsuits become socioeconomic problems, an objective basis system for the term of warranty liability of reinforced concrete constructions is urgent. This study was carried out as a basic study for developing a basis system for the term of warranty liability. To do this, defect data actual collected in apartment complexes were collected and analyzed. As the result of checking the cumulative rate of defect occurrence in reinforced concrete construction by year, the point of time of reaching the 90% level was the 5th years, which was similar with the provision of the Apartment Building Management Act. However, the current Supreme Court precedent has decided that the term of warranty liability for the main structural parts in reinforced concrete construction shall be 10 years and the dispute is expected to continue in the future in the defect lawsuit.