• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.243-248
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• 2002

As a notion of environment protection changes throughout the world, construction engineers, as part of the effort to resolve environmental problems, have been actively doing research on environmental friendly porous concrete using large and non-uniform aggregate. Porous Concrete enables water and air to pass through a firmly hardened material and allows required nutrients to reach roots of plants. The purpose of this study is to analyze planting ability when the change of aggregate gradation and void ratio. The results of an experiment from the planting ability of the porous concrete to its influence on the compressive strength are reported in this paper. As a result of the experiment, the compressive strength is higher when the gradation of aggregate is smaller, and it also goes higher when the void ratio gets smaller The planting ability of porous concrete is decided by the germination and the grass length of Indigofera pseudo-tinctoria(IPT). The length of IPT is longer when the gradation of aggregate is greater and the void ratio gets smaller.

• 호남수학학술지
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• 제32권4호
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• pp.711-738
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• 2010

We list two kinds of gradation of openness and we study in the sense of the followings: (i) We give the definition of IVGO of fuzzy sets and obtain some basic results. (ii) We give the definition of interval-valued gradation of clopeness and obtain some properties. (iii) We give the definition of a subspace of an interval-valued smooth topological space and obtain some properties. (iv) We investigate some properties of gradation preserving (in short, IVGP) mappings.

• Geomechanics and Engineering
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• 제22권2호
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• pp.165-171
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• 2020

Laboratory determination of strength and deformation behavior of clean sands and gravels has always been challenging due to the difficulty in obtaining their undisturbed samples. An alternative solution to this problem is to develop correlations between mechanical properties of cohesionless soils and their gradation characteristics. This study presents database of 3 natural sands with 11 varying particle size gradation curves to allow investigating relationships between mean particle size, maximum and minimum void ratio, relative density and shear strength of the test soils. Direct shear tests were performed at relative densities of 50, 75 and 95% to explore the effects of gradation and density on the angle of internal friction of the modeled sand samples. It is found that the mean grain size D₅₀ bears good correlations with void ratio range (e_max - e_min) and peak angle of internal friction 𝜙'_peak. The generated regression models are in good agreement with published literature and can be considered as reliable for natural sands in Pakistan. These empirical correlations can save considerable time and efforts involved in laboratory and field testing.

• 콘크리트학회논문집
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• 제17권4호
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• pp.631-635
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• 2005

Aggregate gradation effects on cracking-related displacements of concrete are investigated in the laboratory using the German cracking frame. Concrete workability was assessed by use of the slump and drop tests for two different concrete mixtures consisting of gap-graded and dense-graded aggregates. Shrinkage strain, cracking frame strain, and concrete strain were measured and used to compare to strength gain and creep development. The measured and calculated strains of the different aggregate gradations were compared each other. Gradation effects on strength and stress development relative to tensile cracking at saw-cut tip were also investigated. Test results revealed that the gap-graded concrete has indicated larger shrinkage and creep strains than dense-grade concrete perhaps because of its higher volume concrete of cement mortars in the mixture.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제13권1호
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• pp.47-69
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• 2006

In this paper, an idea of graded fuzzy net is introduced; its convergence is studied; Relations between g-net and g-filter are established in L-fuzzy setting.

• 대한토목학회논문집
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• 제35권6호
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• pp.1367-1375
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• 2015

제강슬래그 골재를 사용한 박층 아스팔트 포장공법을 위해 10 mm 밀입도 아스팔트 혼합물의 골재 입도기준을 제시하고자 하였다. 기존 WC-1, WC-3과 같은 밀입도 아스팔트 혼합물의 골재 입도기준은 퓰러모델에 의해 제시되었으나 10 mm 밀입도 아스팔트의 경우 최대밀도선과 유사한 입도를 얻게 되어 부드러운 혼합물이 되는 경향을 나타내었다. 국외 입도기준을 참고하여 골재 맞물림과 최소 골재간극률을 확보하기 유리한 입도를 제시하였다. 제시된 입도의 검증을 위해 골재 입도특성지표인 입도비(GR)와 골재다짐밀도(CAD)를 사용하여 혼합물 물성과의 상관관계를 분석하였다. 골재 입도 및 다양한 특성을 반영할 수 있는 CAD 지표의 $R^2$가 0.86~0.99로 매우 높게 나타났다. CAD 지표를 이용하여 다양한 골재 입도를 검토한 결과 제시 입도기준이 마샬안정도와 VMA 등 배합설계 인자에 보다 안정적인 것으로 나타났다. 또한 균열저항성 향상을 위해 0.3 mm 이하 골재의 통과중량백분율을 10% 이상으로 제한함으로서 터프니스가 약 15% 향상되어 효과적임을 확인 할 수 있었다.

• 한국도로학회논문집
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• 제17권3호
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• pp.27-33
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• 2015

PURPOSES : To ensure appropriate RCC properties with sufficient strength development and workability, it is necessary to secure a proper level of consistency. It is also necessary to secure maximum dry density, which is an important factor for increasing the interaction of aggregate interlocking, leading to an augmentation of RCC strength. On the other hand, the dry density of RCC can be changed owing to the compaction conditions, water content, and particle size distribution. A Proctor test and a modified Proctor test were used for determining the optimum water content needed to achieve maximum dry density with different amounts of compaction energy. A Vebe test, on the other hand, was used for checking the level of consistency, which is important for producing a workable mixture. METHODS : To confirm the degree of compaction at various particle sizes, RCC mixtures with different sand/aggregate ratios were evaluated. The Proctor test and modified Proctor test were applied to these mixtures to check the effect of the aggregate gradation and compaction energy on the maximum dry density and optimum water content. During each test, three specimens were produced for all types of water content under each aggregate gradation. A compaction curve and the optimum water content and maximum dry density for each aggregate gradation were then obtained for both tests. The range of water content for the appropriate consistency of each aggregate gradation was determined through a Vebe test. The optimum water content was then evaluated based on this range. RESULTS : The compaction test results show that the modified Proctor test provides a higher maximum dry density and lower optimum water content compared with the standard Proctor test. For the modified Proctor test, two cases of aggregate gradation (s/a = 30% and 70%) had the optimum water contents outside of the appropriate water content range. For the standard Proctor test, on the other hand, none of aggregate gradations provided the optimum water content within the desired range. CONCLUSIONS : The modified Proctor test should be used for an RCC mixture design because it can provide adequacy between maximum dry density and consistency. Moreover, the compaction roller has become highly developed for higher compaction energy.

• Structural Engineering and Mechanics
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• 제25권1호
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• pp.91-106
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• 2007

A new class of finite elements is described for dealing with mesh gradation. The approach employs the moving least square (MLS) scheme to devise a class of elements with an arbitrary number of nodal points on the parental domain. This approach generally leads to elements with rational shape functions, which significantly extends the function space of the conventional finite element method. With a special choice of the nodal points and the base functions, the method results in useful elements with polynomial shape functions for which the $C^1$ continuity breaks down across the boundaries between the subdomains comprising one element. Among those, (4 + n)-noded MLS based finite elements possess the generality to be connected with an arbitrary number of linear elements at a side of a given element. It enables us to connect one finite element with a few finite elements without complex remeshing. The effectiveness of the new elements is demonstrated via appropriate numerical examples.

• 한국지반공학회지:지반
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• 제3권2호
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• pp.7-16
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• 1987

흙의 동적 특성은 공극비, 구속압력, 입도 등의 여러가지 요인에 의해서 변화한다. 본 연구에서는 모래의 입도가 그 동적 특성에 미치는 영향을 구속압력과 공극비의 영향과 함께 실험적으로 살펴 보았다. 실험 결과, 전단탄성계수(Shear Modulus)와 감쇠비 (Damping Ratio)는 공극비가 감소 함에 따라, 그리고 구속압력이 증가함에 따라 각카 증가 및 감소하였다. 한펀, 실트 크기의 석영분말을 섞어 입도를 변화시켰을 때, 시료의 전단탄성계수와 감쇠비는 석영 분말의 함유량이 증가함에 따라 각각 감소 및 증가하였다. 여기서는 이 현상을 "유효 접촉수"와 "사공간"의 개념을 써서 미시적으로 살펴보았다. 개념을 써서 미시적으로 살펴보았다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1069-1080
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• 2008

The mechanical characteristic of Lightweight Foamed Soil(LWFS) are investigated in this research. LWFS is composed of the in-suit soil, cement and foam to reduce the unit-weight and increase compressive strength. The unconfined compressive tests are carried out on the prepared specimens of LWFS with various soil types to investigate the relationship between compressive strength of LWFS and physical properties of soil. The result indicate that coefficient of gradation($C_g$) and liquid limit(LL) are more important factor affecting compressive strength than other physical properties of soil and coefficient of gradation($C_g$) and liquid limit(LL) can standard to determine the optical soil among the in-situ soils for LWFS.