• Geomechanics and Engineering
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• 제11권1호
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• pp.161-175
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• 2016

A series of experimental studies are conducted on the deformation and shear strength property of compacted loess. The results reveal that the relationships of both the initial moisture content (w) and the initial degree of compaction (K) of compacted loess with cohesion (w) and the angle of internal friction (${\varphi}$) are linear. The relationship between the secant modulus ($E_{soi}$) and K is also linear. The relationship between $E_{soi}$ and w can be fitted well by a second-order polynomial. Further, when the influences of w and K are ignored, the relationship between the confined compression strain (${\varepsilon}$) and vertical pressure (p) can be expressed by a formula. A correction formula for the deformation of compacted loess caused by a change in w and K is derived on the basis of the study results.

• 한국재료학회지
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• 제19권12호
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• pp.674-679
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• 2009

Yttria stabilized zirconia single crystals show plastic deformation at high temperatures by activating dislocations. The plastic deformation is highly dependent on crystallographic orientation. When the samples were deformed at different orientations, stress-strain curves changed by operating different slip systems. The strength of samples was also highly dependent on crystallographic orientation, i.e., samples without yield drop showed higher strength than that of samples exhibiting yield drop. The slip systems in the sample deformed along <112>, <111> and <001> agreed with the theoretical values of the plastic deformation, following Schmid's Law. Dislocations play a major role in the plastic deformation of this crystal. At the early stages of plastic deformation, all samples exhibited dislocation dipoles and, in the later stages, dislocation interactions occurred by forming nodes, tangles and networks. In this study, three different orientations, [11-2], [111] and [001] were employed to explain the plastic deformation behavior. A microstructural analysis was performed to elucidate the mechanism of the plastic behavior of this crystal.

• 소성∙가공
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• 제7권1호
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• pp.36-48
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• 1998

In order to analyze the stretch flange forming characteristics of tailored blanks. laser welded blanks of different thickness and strength combinations were prepared and hole expansion tests were done. The stretch flange formability of laser welded blanks was reduced as increasing the deformation restraining force($strength{\times}thickness$) ratio between two welded sheets. Simulation of stretch forming mode deformation and comparson with experimental results showed that the stretch flange formabili-ty was influenced not only by the difference of the deformation restraining forces between two base sheets but also by the difference of the deformation restraining forces between base sheet and weld. Therefore the stretch flange formability was reduced more rapidly than tensile elongation as increas-ing the deformation restraining force ration. It was also found that simulation of stretch flange forming was more accurate when material properties of weld was given.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1245-1251
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• 2005

The deformation modulus is an important variable which can be used to predict settlement of structures, analyze horizontal directions of piles and design roads. Though to predict deformation modulus relationships using standard penentration test N-value and undrained shear strength were suggested , these relationships are not appropriate in domestic areas because these relationships are based on foreign areas. Therefore, in this study, with field test results, reasonable equations in domestic area are suggested to estimate deformation modulus.

• 한국지반공학회논문집
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• 제27권8호
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• pp.31-37
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• 2011

본 연구에서는 정적 다짐된 자연 성해 실트질 모래의 불포화 흡수력의 영향과 변형특성을 평가하기 위해서 불포화 일축압축시험을 수행하였다. 공시체는 초기포화도를 다르게 하여 제작되었고 공시체의 초기 흡수력 및 최대일축압축강도에서의 흡수력 그리고 전단시의 체적변형이 측정되었다. 시험결과, 초기포화도의 크기에 따라 흡수력, 최대 일축 압축강도 및 체적변형 거동을 살펴보고 평가할 수 있었다. 또한, 불포화상태 실트질 모래의 전단강도에서 흡수력에 의해 증가하는 겉보기 점착력을 나타내는 흡수응력($P_s$을 추정하였다.

• Steel and Composite Structures
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• 제29권5호
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• pp.659-667
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• 2018

This paper deals with the experimental study on strength the strength and deformation characteristics of short circular Concrete Filled Steel Tube (CFST) columns. Effect of vertical stiffeners on the behavior of the column is studied under axial compressive loading. Intermittently welded vertical stiffeners are used to strengthen the tubes. Stiffeners are attached to the inner surface of tube by welding through pre drilled holes on the tube. The variable of the study is the spacing of the weld between stiffeners and circular tube. A total of 5 specimens with different weld spacing (60 mm, 75 mm, 100 mm, 150 mm and 350 mm) were prepared and tested. Short CFST columns of height 350 mm, outer tube diameter of 165 mm and thickness of 4.5 mm were used in the study. Concrete of cube compressive strength $41N/mm^2$ and steel tubes with yield strength $310N/mm^2$ are adopted. The test results indicate that the strength and deformation of the circular CFST column is found to be significantly influenced by the weld spacing. The ultimate axial load carrying capacity was found to increase by 11% when the spacing of weld is reduced from 350 mm to 60 mm. The vertical stiffeners are found to effective in enhancing the initial stiffness and ductility of CFST columns. The prediction models were developed for strength and deformation of CFST columns. The prediction is found to be in good agreement with the corresponding test data.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.366-369
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• 2006

Deformability of RC members in shear is controlled by governing failure modes and material strength. Shear strength of members in D-regions has been explained by a direct load path (direct strut or arch action) and indirect load path (fan action or truss action). Indirect load path including truss action and fan action rely on bond along tension ties. Generally, superposition of two actions results in total shear strength when shear failure modes control. The ultimate deformation depends on controlling failure modes and thereby, their force transfer patterns. Proposed models are capable of explaining of limited deformability of RC members in D-regions.

• 한국도로학회논문집
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• 제13권4호
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• pp.61-70
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• 2011

본 연구에서는 아스팔트 콘크리트의 전단 물성을 고려한 영구변형 예측 모델을 개발하였다. 아스팔트 콘크리트의 전단 물성과 영구변형과의 상관성을 고찰하기 위해서 세 가지 종류의 아스팔트 콘크리트에 대해서 반복재하삼축압축(RLTC) 시험 및 삼축압축강도 시험과 간접인장강도 시험을 다양한 하중과 온도 조건에서 시행하였다. 주어진 아스팔트 콘크리트에 대하여 온도가 증가함에 따라 점착력은 감소하였으나 온도가 $40^{\circ}C$ 이상인 경우 마찰각은 온도 변화에 민감하지 않은 거동을 나타내었다. 축차응력, 구속압, 온도 및 하중 주파수가 영구변형에 미치는 영향이 크다는 것을 관측할 수 있었다. 이러한 실내 시험 결과로 부터 아스팔트 콘크리트의 전단물성과 하중재하시간에 기초한 영구변형 모델을 개발하였다. 또한 일반적인 포장 단면에서 실시한 포장가속시험 결과를 이용해서 영구변형 모델을 보정하였다. 본 연구에서 제안한 영구변형 모델을 이용하여 다양한 온도와 하중조건에서 아스팔트 콘크리트의 영구변형을 예측할 수 있었다.

• Journal of Biosystems Engineering
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• 제17권2호
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• pp.156-170
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• 1992

The force-deformation relationship gives the basic physical properties of the fruits such as the bioyield point, the rupture point, and the deformations at the bioyield point and the rupture point. These informations are very important to study the stress-strain relationships of the fruits. This study was conducted to analyze those physical properties according to the sampling position of the fruits, and to determine the bioyield point, the rupture point, and the deformations at the bioyield point and the rupture point of the fruits for two different storage conditions(low temperature and normal temperature) and the storage period, and to investigate the effect of loading rate on those physical properties, the hysteresis on the loading-unloading condition and the degree of elasticity of the fruits. The results of the study were as follows : 1. The physical properties(BS, US, BD, and RD) of the test specimen selected from the different sampling positions were quite different. The values of the physical properties were shown smallest ones at the cheek of the fruits, and the statistical test results of the physical properties between the cheek from the other two positions of the fruits showed that there were significant difference at the 1 % level between them. 2. The effect of loading rate on the physical properties of the fruits was relatively large, all the considered physical propertis of the fruits increased with the loading rate, but the hysteresis loss decreased with it. 3. The physical properties of the fruits according to the storage conditions and period showed different, and the bioyield deformation and the rupture deformation of the fruits increased with the storage period, but the bioyield strength and the ultimate strength of the fruits decreased with it. The effect of the storage conditions on the those physical properties showed that the normal temperature storage condition was a little higher than the low temperature storage condition. 4. As a whole, it was shown that the bioyield strength and the ultimate strength of the pear decreased a little faster than those of the apple, and the bioyield deformation and rupture deformation of the pear increased a little faster than those of apple at the two storage conditions.

• International Journal of Concrete Structures and Materials
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• 제18권1E호
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• pp.55-61
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• 2006

RC shear walls are frequently used as lateral force-resisting system in building construction because they have sufficient stiffness and strength against damage and collapse. If RC shear walls are properly designed and proportioned, these walls can also behave as ductile flexural members like cantilevered beams. To achieve this goal, the designer should provide adequate strength and deformation capacity of shear walls corresponding to the anticipated deformation level. In this study, the level of demands for deformation of shear walls was investigated using a displacement-based design approach. Also, deformation capacities of shear walls are evaluated through laboratory tests of shear walls with specific transverse confinement widely used in Korea. Four full-scale wall specimens with different wall boundary details and cross-sections were constructed for the experiment. The displacement-based design approach could be used to determine the deformation demands and capacities depending on the aspect ratio, ratio of wall area to floor plan area, flexural reinforcement ratio, and axial load ratio. Also, the specific boundary detailing for shear wall can be applied to enhance the deformation capacity of the shear wall.