• 자원환경지질
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• 제8권4호
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• pp.203-210
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• 1975

The engineering properties of some Gyeongsang sedimentary rocks with respect to the grain size and the orientation of bedding planes were studied. The suitability of the rocks for civil and architectural construction was also investigated. The porosity of the rocks increases in proportion to the grain size. The ratio of the strain due to stress perpendicular to the bedding planes to the strain resulting from stress parallel to the bedding planes increases as the grain size decreases. The study indicates however, that the ratio of Young's modulus due to stress perpendicular to the bedding planes to Young's modulus resulting from stress parallel to the bedding planes increases in proportion to the grain size. The compressive strength of the sandstones studied is much greater than the strength of the conglomerate or shale. Only the coarse grained sandstone can be used for civil and architectural construction, regardless of the orientation of bedding planes. The relationships between compressive strength and density, elasticity and porosity, and compressive strength and mineral content were also studied.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 가을 학술발표회 논문집
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• pp.148-153
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• 1996

Concrete with ground granulated blast-furnace slag can be affected by frost attack because the reaction of hydration is slow at the early age. In this study, therefore, the freezing and thawing test has been carried out to investigate the freezing and thawing resistance on concrete with ground granulated blast-furnace slag. The freezing and thawing test has been performed on concrete a blended cement, which was substituted by ground granulated blast-furnace slag with 4 kinds of ratio (non-admixture, 20%, 40% and 60%). And also tested on concrete added the AE agents to the concrete of same mix proportion to search the improvement effects about the resistance. As a result, the freezing and thawing resistance showed a tendency of reduction in proportion to the increase of the substitution ratio. For non-AE concrete, resistances of the freezing and thawing were very poor as the durability index indicated less than 5.8%. For AE concrte, resistance of the freezing and thawing were excellent as the durability index indicated more than 80.9%.

• 대한수학교육학회지:학교수학
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• 제10권4호
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• pp.603-623
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• 2008

이 논문의 목적은 비와 비례 과제에서 가법적 전략을 사용하는 학생의 문제해결 과정에서 나타난 수학적 표현을 분석하여 가법적 전략을 사용하는 학생의 수학적 표현이 비와 비례 과제를 해결하는데 어떤 영향을 미치는지 탐구하기 위한 것이다. 가법적 전략은 비와 비례 문제를 해결하는 과정에서 학생에게 많이 나타나는 오류 중의 하나로, 한 양에서 다른 양을 빼어 그 차를 다른 양에 적용하는 전략이다. 학생의 응답을 분석한 결과 학생의 가법적 전략의 유형은 단위를 고려하지 않고 빼기, 전체에서 부분을 뺀 양과 부분 비교하기, 차만큼 더하기, 차만큼 빼기로 나눌 수 있었다. 학생의 가법적 전략을 승법적 전략으로 변화시키기 위해 단위량을 구하도록 유도하였고, 이 과정에서 다음과 같은 특징이 나타났다. 첫째, 두 수 사이의 관계가 정수배가 아닌 경우 똑같이 곱하고 빼어서 원하는 수를 만든다. 둘째, 자연수와 자연수 사이의 중간값으로 표현한다. 셋째, $a{\div}b$를 $\frac{a}{b}$가 아닌 소수로 표현한다. 넷째, 큰 수를 작은 수로 나눈다. 이상과 같은 결과는 나눗셈과 분수 표현을 잘 관련짓지 못하는 것이 가법적 전략에서 승법적 전략으로의 전환을 어렵게 하고 있음을 보여준다.

• 토지주택연구
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• 제12권4호
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• pp.127-137
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• 2021

그라우팅 공법은 지반 내 토목구조물 활용 시 지반 강도특성을 증진시키거나 지하공간 활용 시 차수효과를 위하여 활발하게 적용되고 있다. 최근에는 그라우팅 기밀특성을 향상시키기 위하여 벤토나이트가 시멘트 재료와 함께 활용되고 있다. 이러한 벤토나이트-시멘트 그라우팅 재료의 원활한 주입을 위해서는 주입재료의 배합비율에 따른 특성을 사전에 파악하는 것이 중요하다. 본 연구에서는 그라우팅 재료로 주로 활용되고 있는 1종 보통 포틀랜드 시멘트와 벤토나이트를 이용하여 물/시멘트 배합비율 및 벤토나이트 함량에 따른 점성도 및 블리딩 발생비율을 분석하였다. 실험결과, 물/시멘트 배합비율이 감소하거나 벤토나이트 함량이 증가할수록 점성도는 급격히 증가하고 블리딩 비율은 감소하는 반비례 경향을 보였다. 또한, 적합한 재료 선정 기준에 따라 물/시멘트 배합비율 따른 적용가능한 벤토나이트 함량을 선정하였다. 본 연구에서 분석한 벤토나이트-시멘트 그라우팅 재료의 평가 결과는 향후 지반 내 적합한 그라우팅 재료 선정을 위하여 유용하게 활용될 수 있을 것으로 기대된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.255-258
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• 1999

In recent years, the study on the porous concrete which has excellent permeability is actively advanced in the field of architectural and civil engineering. But porous concrete has a reciprocal concept in the aspect of comparative large and continuos void structure and reduction of void for insurance of the necessary strength on the mixing proportion, must have satisfied of the properties of these. Therefore this study is series of experiment for the strength elevation and evaluated the effect according to fine replacement ratio and levels of cement content. As a result, the strength of porous concrete was elevated by an increase of fine replacement ratio and cement content.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 춘계 학술논문 발표대회 1부
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• pp.131-132
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• 2011

This study analyzes the yearly-best delivered size range of truck mixer based on the specified mix, Water to Binder Ratio, aggregate proportion and unit amount with statistical method targeting on Kyeongi and Kyeongsang province and compares with the similar materials of Japan to propose as a basic standard for the quality control of mixer truck. As a result, in case of the Water to Binder Ratio of these areas, it is higher than Japan's due to the excessive safety rate reflecting the changes of differential value impact and unit amount, and the unit amount's standard deviation is very large by reflecting the changes of the amount used and chemical admixture susceptibility. In case of aggregate proportion, the frequency rate is about 50%, which is very similar value with Japan's one.

• Computers and Concrete
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• 제21권6호
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• pp.705-715
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• 2018

This paper presents an experimentally investigation pertinent to the mechanical properties of rubberized mortar (RM) with styrene-butadiene rubber (SBR). The SBR were used with constant water-to-cement ratio of 0.485 and two different volume proportion of SBR particles were utilized as aggregates. One types of SBR particles with fineness modulus of 4.951 were utilized 0%, 10%, and 20% of aggregate volume. Effectiveness of SBR replacement ratio, curing and aging effect on the compressive strength, flexural strengths as well as load-displacement. Compressive and flexural strength of concrete were investigated at the end of 28-days and 56-days age. Obtained results demonstrated that utilization of SBR reduced the flexural strength of SBR mortar at the earlier curing age while SBR increased. Moreover, mechanical properties of mortar mentioned above were significantly affected by the water cure timing with an increasing proportion of the replacement level of SBR.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.533-536
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• 2003

The objective of in this study makes investigation into the characteristics of antiwashout underwater concrete as to mix proportion, casting and curing water through experimental researches. in this study, sea sand is blended with river sand, crushed sand is blended with river sand and sea sand as to investigate the quality change and characteristics of antiwashout underwater concrete with variation of blend ratio of sea sand and crushed sand(0, 20, 40, 60, 80, 100%). Higher compressive strength is measured following the order of river sand, sea sand, crushed sand regardless of age and casting condition. Except for case of using river sand, blended ratio of 40% is appeared on most compressive strength.

• 대한기계학회논문집B
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• 제20권10호
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• pp.3282-3292
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• 1996

Flow velocity was measured using a hot wire anemometer. Turbulence intensity was in proportion to mean flow velocity regardless of swirl velocity. And integral length scale has proportional relation with swirl velocity regardless of measurement position. Flame speed calculated by radius of visualized flame was increased and then decreased according to lapse of time from spark. Maximum flame speed was increased according to increase of turbulence intensity. Burning speed and flame transport effect increased with increase of swirl velocity, but ratio of burning speed to flame speed decreased with increased of swirl velocity. Mass fraction burned versus volume fraction burned was increased in proportion to the increase of turbulence intensity, caused by increase of combustion promotion effect according to increase of turbulence intensity and scale.

• 한국수학사학회지
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• 제20권2호
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• pp.89-108
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• 2007

많은 학생들에게 소수의 곱셈은 의미 있게 학습, 지도되지 못한다. 이와 관련하여, 이 글에서는 Dewey, Vergnaud, Brousseau의 관점에서 소수 곱셈의 본질은 비와 비례관계의 인식에 있음을 드러내었다. 이를 토대로 한국과 일본 교과서에서 소수곱셈을 다루는 방식을 비교하고 그 특징을 살펴본 후, 우리나라 교과서에서 소수곱셈을 보다 의미 있게 전개하기 위한 제언을 하였다.