• 콘크리트학회논문집
• /
• 제13권3호
• /
• pp.237-243
• /
• 2001

본 논문에서는 플라이애시 콘크리트의 재령에 따른 변화를 예측하기 위한 모델식을 제시하고 그 모델식의 유효성을 검토하였다. 기존에 행해졌던 실험결과를 모델식을 이용하여 회귀분석한 후에 그 결과를 플라이애시 대체량과 물-시멘트비에 따라 분석하였다. 해석결과에 의하면 예측 모델식은 실험결과를 일정오차내에서 잘 모델링하였다. 그러나 물-시멘트비가 매우 작은 경우에는 플라이애시 대체량이 증가하면 실험값과 예측값의 오차가 조금 증가하는 경향을 나타내었다. 플라이애시 대체량이 증가할수록 한계상대압축강도의 크기가 증가하였고 초기 겉보기 활성에너지도 한계상대압축강도와 같이 플라이애시 대체량이 증가할수록 증가하였다. 0.40이하의 물-시멘트비에서는 한계상대압축강도와 겉보기 활성에너지의 크기가 일정하고 물-시멘트비가 0.40을 초과하면 물-시멘트비의 증가에 따라 한계상대압축강도와 겉보기 활성에너지가 조금씩 증가하였다.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
• /
• pp.156-157
• /
• 2017

It is possible in the case of the chemical admixtures for concrete currently being used in actual work sites to omit quality evaluation and replace it with the scores of the admixture manufactures; this can create a problem of decline in reliability in quality on the work site. Therefore this study sought to analyze the degree of influence changes in the solid content rate of lignin- and naphthalene-based water-reducing agents have on the fundamental characteristics of cement mortar. The results showed that in fresh mortar, the flow and amount of air decreases with decrease in the solid content ratio. In hardened mortar, the condensation strength had hardly any effect on the use of lignin-based water-reducing agent, but naphthalene-based water-reducing agent increased with the decrease in the solid content ratio.

• 한국식품조리과학회지
• /
• 제14권4호
• /
• pp.327-332
• /
• 1998

물비율에 따른 열무 물김치의 발효특성을 조사하기 위해 담금수의 비율을 1/1.14, l/l.5, 1/2, 1/2.75, 1/4로 각각 달리하고 발효숙성 온도를 4$^{\circ}C$, 15$^{\circ}C$, $25^{\circ}C$로 조절하여 열무 물김치를 제조한 후 pH, 산도, 총 비타민C 함량, 미생물균수의 변화를 측정하였고 물비율이 관능적 특성에는 어떠한 영향을 미치는지 함께 살펴보았다. 위의 비율대로 열무 물김치를 제조했을 때, pH와 미생물 변화는 온도별, 시료별로 큰 차이를 보이지 않았고 산도는 온도와 상관없이 물비율이 작을수록 높게 나타났다. 총 비타민 C 함량도 물비율이 작을수록 높음을 알 수 있었다. 관능검사에서는 신냄새, 신맛, 새콤한 맛에서 시료간 차이를 보였는데 각각의 항목에서 물비율 1/1.14 시료가 다른 시료들과 유의적으로 강하게 나타났다. 전반적인 기호도면에서는 유의적인 차이는 없었지만 물비율 1/2가 가장 우수했으며 이어서 l/l.5, l/l.14, 1/2.75, l/4순으로 높게 나타났다. 또한, 총 비타민 C가 김치의 신맛과 풍미와 상관관계가 있음을 알 수 있었다.

• Journal of Plant Biology
• /
• 제18권4호
• /
• pp.143-149
• /
• 1975

For the evaluation of drought resistance of the plant, the growth of Lespedeza bicolor Turcz. var. japonica Nakai was analyzed by the control of water content of soil: 1. The growth of leaf, stem and root showed high value in accordance with the increase of soil water content. 2. The formation of nodule was alos increased as the content of soil water became higher. 3. The highest water content of the plant was shown in the plots of 30 and 40% of water centent in soils and in the middle of the growing period (August-September). 4. The C/F ratio in the early period of the growth(July) was similar in each plot, but showed a higher value as the water centent of soil became higher at the later period(October). 5. The T/R ration increased in early period of the growth as the soil water content became higher, but it was decreased to the value of 1 in each plot.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
• /
• pp.657-660
• /
• 2006

Recently, very-early strength latex-modified concrete(below ; VES-LMC) has been developed for repairing and overlaying the old concrete bridge deck. Early-age defects in high-performance concrete due to thermal and autogenous deformation shorten the life cycle of concrete structures. Thus, it is necessary to examine the behavior of early-age concrete at the stages of design and construction. The purpose of this study was to evaluate the autogenous shrinkage of VES-LMC, having an experimental variables such as retarder and water-cement ratio. The greater the retarder content in VES-LMC, the greater the expansion at early-age. This recommend the small retarder content as possible. The effect of water-cement ratio on early-age behavior is very small, because of the wrapped specimen in order to prevent water evaporation.

• 자원환경지질
• /
• 제22권2호
• /
• pp.141-150
• /
• 1989

In order to make economic and geological evaluation of coal in Korea, proximate and ultimate analyses were carried out as well as coal petrological studies such as maceral analyses, vitrinite reflectance and sporinite fluorescence measurement. The coeffcient of correlation between each factor of both conventional utilization and coal petrological parameters were studied as in Table 5 and 6. Their conclusions were as follow: (1) for anthracite, the good parameters of coal rank are mean vitrinite reflectance, carbon content, hydrogen content and H/C atomic ratio: (2) for brown coal and sub-bituminous coal, the good parameters of coal rank are carbon content, calorific value, moisture content, hydrogen content, oxygen content and O/C atomic ratio as well as vitrinite reflectance and sporinite fluorescence. An attempt is made to infer the coalforming environment by utilization of coal petrological analyses and to make comparison of coal analyses with proximate and ultimate analyses throughout the island arc region including Japan, Philippine and Indonesia and continental region including USA, Canada and Australia. As a result, meceral composition of Paleozoic and Mesozoic anthracite are similar to that of the Paleozoic continental coals, which were formed under dry conditions or low water table, but the coalification degree suddenly increased during Daebo orogeny (middle Jurassic to lower Cretaceous). The Tertiary coal resembles those of Tertiary island arc region coal characterized by higher calorific value, volatile matter content and H/C atomic ratio and by the formation of coal under wet conditions or higher water table.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
• /
• pp.1035-1040
• /
• 2001

The effects of polymer-binder ratio and slag content on the properties of combined wet/dry-cured polymer-modified mortars using granulated blast-furnace slag (slag) are examined. As a result, the flexural and compressive strengths of polymer-modified mortar using slag reaches a maximum at a slag content of 40%, and is inclined to increase with increasing polymer-binder ratio. The water absorption, carbonation depth and chloride ion penetration depth tend to decrease with increasing polymer-binder ratio and slag content.

• 한국건설순환자원학회논문집
• /
• 제2권4호
• /
• pp.321-327
• /
• 2014

경량골재콘크리트는 구조물의 자중경감을 목적으로 경량골재를 적용하여 제조한 콘크리트로 구조물의 고층화 및 대형화에 효과적으로 대응할 수 있는 장점이 있다. 하지만 경량골재는 다공체이므로 화재와 같은 고온에 노출되는 경우 수증기압이나 열응력에 의해 골재 주변으로 응력이 집중될 가능성이 커 폭렬이 발생하기 쉽다. 본 연구는 구조용 경량골재를 사용한 1종 경량골재콘크리트의 함수율과 내화특성과의 관계를 검토코자 하며, 실험결과 압축강도와 함수율이 높은 경량골재콘크리트는 폭렬의 가능성이 높기 때문에 흡수율이 작은 골재의 사용이나 폭렬방지를 위한 대책이 필요하다.

• International Journal of Concrete Structures and Materials
• /
• 제9권2호
• /
• pp.185-206
• /
• 2015

This paper presents statistical models developed to study the influence of key mix design parameters on the properties of lightweight self-consolidating concrete (LWSCC) with expanded shale (ESH) aggregates. Twenty LWSCC mixtures are designed and tested, where responses (properties) are evaluated to analyze influence of mix design parameters and develop the models. Such responses included slump flow diameter, V-funnel flow time, J-ring flow diameter, J-ring height difference, L-box ratio, filling capacity, sieve segregation, unit weight and compressive strength. The developed models are valid for mixes with 0.30-0.40 water-to-binder ratio, high range water reducing admixture of 0.3-1.2 % (by total content of binder) and total binder content of $410-550kg/m^3$. The models are able to identify the influential mix design parameters and their interactions which can be useful to reduce the test protocol needed for proportioning of LWSCCs. Three industrial class ESH-LWSCC mixtures are developed using statistical models and their performance is validated through test results with good agreement. The developed ESH-LWSCC mixtures are able to satisfy the European EFNARC criteria for self-consolidating concrete.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2009년도 춘계 학술논문 발표대회 학계
• /
• pp.45-48
• /
• 2009

The performance of concrete mainly depend upon its water-cement ratio. If water percentage is excess in concrete, it may cause the degradation of performance. Because of these reasons, the change of water content is managed by using various evaluation method of unit water content. And criterion for the change of water content is regulated and used. However the criterion is set only considering production error and measurement error but criterion does not consider performance degradation of concrete. Therefore this study tries to investigate degradation of performance while adding extra water by artificial manipulation or management error in concrete, The contents of extra water for tests are set as 0, 20, 40, 60kg/m3, to examine the performance degradation of concrete, strength, shrinkage, cracks, carbonation are tested This study conclude that, when extra water content is excess than 20kg/m3 in concrete, then performance level of concrete declined rapidly. 80 it is very important to maintain quality of concrete for its better performance.