• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.365-370
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• 1999

SKD11 is one of the most difficult workpiece for machining, so it is necessary to evaluate the machining characteristics of SKD11. The workpiece was made to be the pipe form and heat-treated to HRC45. In this paper, the orthogonal cutting experiment of this material was carried out with TiAlN coated WC cutting tool of 4 kinds of rake angle. After cutting experiment, cutting characteristics of SKD11 were investigated according to variation of cutting speed, feedrate and rake angle.

• Journal of Korean Association for Spatial Structures
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• v.4 no.3 s.13
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• pp.49-56
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• 2004

This paper predicted the shear deformation, such as strain of shear reinforcement and shear track width, of reinforced concrete (RC) members using Transformation Angle Truss Model (TATM) in order to apply to the shea, analysis of RC buildings. To check the validity of TATM for the shear deformation of RC beams, four RC beams with different shear span-to-depth ratios were cast, instrumented and tested. Observed results were compared with theoretical results by MCFT(Response-2000), RA-STM, FA-STM, and TATM. The proposed model, TATM, better predicted the relationships of the shear stress-strain of shear reinforcement and the shear stress-shear track width than other truss models.

• Journal of the Korean Geosynthetics Society
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• v.5 no.3
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• pp.25-30
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• 2006

Large-scale direct shear tests were conducted in order to evaluate both the shear strength of soil itself and the interface shear strength between soil and woven geotextile. Two types of soil (sand and clay) with a woven geotextile were used in the experimental program. Total nine tests were conducted in this study. It has been found from the experimental results that the friction angle of sand itself were $30^{\circ}$. Interface friction angle between woven geotextile and sand showed $26^{\circ}$ indicating an efficiency of 87%. Similarly, interface friction angle between woven geotextile and clay showed $7.7^{\circ}$.

• Magazine of the Korea Concrete Institute
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• v.3 no.3
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• pp.141-148
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• 1991

Investigations on the behavior of steel fiber reinforced high strength concrete beams subjected to predominant shear are accomplished to determine their diagonal shear strength including ultimate shear strength. The par¬ameters varied were the fiber volume fraction(Vf) of the steel-fibers and shear span to depth ratio(a/d). The test result show that diagonal shear strength and ultimate shear strength are increased significantly due to crack arrest mechamsm. Predictive equations are suggested for evaluating the diagonal cracking strength and ultimate shear strength of the fiber reinforced high strength concrete beams.

• Journal of the Korean GEO-environmental Society
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• v.7 no.3
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• pp.31-41
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• 2006

The scale effect of specimens on the shear behavior of joints is studied by performing direct shear tests on six different sizes in Granite. The peak and residual shear stress, shear displacement, shear stiffness, and dilation angle are measured with the different normal stress(0.29~2.65MPa) and roughness parameters. It is also shown that both the joint roughness coefficient(JRC) and the joint compression strength(JCS) reduce with increasing joint length. A series of shear tests show about 56~67% reduction in peak shear stress, and about 18~44% in residual shear stress, respectively as the contact area of joint increases from 12.25 to $361cm^2$. Also the variation of dilation angle is $27^{\circ}$ at normal stress of 0.29 MPa and $6^{\circ}$ at normal stress of 2.65 MPa, respectively. The envelopes considering scale effect for JRC are made for the peak shear strength of rock joint in comparison with the Barton's equation.

• Journal of the Society of Disaster Information
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• v.15 no.4
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• pp.590-596
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• 2019

Purpose: An experimental study was conducted on the sand samples for the size effect of the test specimens, one of the problems of the direct shear test. Method: Jumunjin standard sand, a representative sand of Korea, was used as sand sample. The large direct shear test was performed to analyze the shear strength at 50%, 60%, 70%, and 80% relative density, and then the comparative results were compared with the test results of the small direct shear test. Result: It was analyzed that the internal friction angle of the small shear tester tended to be relatively large in the dense region. It was analyzed that the results of the large shear tester tend to be relatively large in the region of medium relative density. Conclusion: The size effect on the samples in the direct shear test on sandy soil was analyzed to be relatively small.

• Tunnel and Underground Space
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• v.26 no.5
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• pp.384-395
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• 2016

Both the roughness measurement tests and the multi-stage shear tests were carried out on the 110 rock joint samples in order to investigate the influences of rock type, joint roughness and normal stress on the shear behaviour of rock joints. Test samples were composed of quartz porphyry, dacite, granite and gneiss, which were classified into three detailed groups according to their JRC values. Roughness parameters of rock joints were analyzed by roughness measurement tests, and shear characteristics were also investigated by multi-stage shear tests. Both peak shear strength and shear stiffness were increased as both joint roughness and normal stress were increased, whereas dilation angles showed lower values at the lower roughness and higher normal stress conditions. Besides, shear characteristics obtained from all tests of four different rock types with different rock strengths showed irrelevant details, therefore the influences of both joint roughness and normal stress on shear behaviors were found to be more considerable than the strength of intact rock. The results obtained from both multi-stage shear tests and direct shear tests were finally compared, where the dilation angles obtained from multi-stage shear tests were found to be valid only for the first normal stress conditions.

• Journal of the Korean Geotechnical Society
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• v.25 no.4
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• pp.39-54
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• 2009

Large scale direct shear tests were carried out to analyze the shear behavior of crushed rocks at local representative quarries. Shear strength for each specimen was derived and the effects on shear behavior induced by the variation of factors such as particle size, water immersion, density, uniformity coefficient, and particle breakage were evaluated and quantitatively compared with previous studies. The opportunity was also taken to identify stress-dilatancy relation of crushed rocks following the energy-based theory and friction coefficients at critical state as well as peak friction angles and dilation angles were estimated. As a result of tests it was found that uniaxial compressive strength and particle breakage of the parent rocks have crucial effect on internal friction angles; in addition, dilatancy at the failure showed strong relationship as well.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.408-412
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• 2007

본 연구는 자갈하상하천에서 하상에 분포하는 입자에 작용하는 전단력을 이용하여 등가조도를 산정할 수 있는 모형을 개발하였다. 등가조도는 기존의 연구들처럼 경험적으로 특정입도에 의해 산정하지 않고 하상에 분포하는 각 입자에 작용하는 입자 전단력을 산정하고, 하상 평균전단력과의 관계로서 산정하였다. 입자 전단력은 항력을 통해 산정하였으며, 이때 항력계수는 입자의 돌출 높이를 고려할 수 있도록 하였다. 또한 입자에 부딪히는 평균유속은 수치적분을 통해 입자의 돌출 높이에 따라 가변성을 고려할 수 있도록 식으로 제시하였다. 단위면적당 입자 전단력과 하상 평균 전단력과의 관계를 통해 등가조도의 함수로서 식을 제시한 후 수치해석방법의 하나인 증분 탐색법을 통해 등가조도를 산정할 수 있도록 하였다. 그리고 산정된 등가조도를 이용하여 수위-유량관계 및 흐름저항매개변수를 산정하여 적정성을 검토하였다.

• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.353-362
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• 2015

Cyclic loading tests for the PC moment frame with plastic shear hinges were performed to evaluate the seismic performance. The plastic shear hinges consisted of two steel plates were installed at the mid-length of the beam to connect the PC frames. Three shear links are existed in each steel plate. The three shear links were designed using shear force corresponding to the shear capacity of 50%, 75%, and 100% of the beam shear capacity. The proposed connections showed an efficient energy dissipation capacity and good structural performance. As a result, it is reasonable to design the plastic shear hinges using design shear capacity less than 100% of the beam shear capacity.