• Journal of the Korean Institute of Gas
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• v.1 no.1
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• pp.95-100
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• 1997

In order to predict the elastic-plastic fracture toughness for metallic materials, Finite Element Method(FEM) was used for analysis of compact tension specimen. ASTM E399 test procedure was adopted for simulation of FEM. The Load-Crack Mouth Opening Displacement curve obtained from this analysis was used to detect the crack initiation point and determine the elastic-plastic fracture toughness $J_{IC}$. In order to prove the results, they were compared with the results from previous experiments and they agree with experimental results.

• Steel and Composite Structures
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• v.15 no.6
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• pp.659-677
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• 2013

This paper introduces new specimens of Steel-Carbon Fibre Reinforced Polymer composite developed in accordance with standard test method and definition for mechanical testing of steel (ASTM-A370). The main purpose of this research is to study the behaviour of steel-CFRP composite specimen under uniaxial tension to use it in beams in lieu of traditional steel bar reinforcement. Eighteen specimens were prepared and divided into six groups, depending upon the number of the layers of CFRP. Uniaxial tensile tests were conducted to determine yield strength and ultimate strength of specimens. Test results showed that the stress-strain curve of the composite specimen was bilinear prior to the fracture of CFRP laminate. The tested composite specimens displayed a large difference in strength with remarkable ductility. The ultimate load for Steel-Carbon Fibre Reinforced Polymer composite specimens was found using the model proposed by Wu et al. (2010) and nonlinear FE analysis. The ultimate loads obtained from FE analysis are found to be in good agreement with experimental ones. However, ultimate loads obtained applying Wu model are significantly different from experimental/FE ones. This suggested modification of Wu model. Modified Wu's model which gives a better estimate for the ultimate load of Steel-Carbon Fibre Reinforced Polymer (SCFRP) composite specimen is presented in this paper.

• International Journal of Ocean System Engineering
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• v.3 no.4
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• pp.209-217
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• 2013

This paper presents a mooring design procedure for a floating offshore wind turbine. Offshore environmental data for Jeju are taken from KHOA (Korea Hydrographic and Oceanographic Administration) and used for the environmental conditions in numerical analyses. A semi-submersible-type floating wind system with a 5-MW-class wind turbine studied by the DeepCwind Consortium is applied. Catenary mooring with a studless chain is chosen as the mooring system. Design deliverables such as the nominal sizes of chain and length of the mooring line are decided by considering the long-term prediction of the breaking strength of the mooring lines where a 100-year return period is used. The designed mooring system is verified using a fatigue calculation based on rain-flow cycle counting, an S-N curve, and a Miner's damage summation of rule. The mooring tension process is obtained from time-domain motion analyses using ANSYS/AQWA.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.11
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• pp.3498-3506
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• 1996

A loading device to be used in fracture experiment is presented. It's loading angle can be adjusted from $-45^{\circ}$ to $105^{\circ}$ at intervals of $15^{\circ}$ for a CTS ( compact tension-shear) specimen, so that it is to be useful to measure mixed mode toughness. The equations to give the $K_ I$, $K_ I1$ and J-integral for the experiment are evluated though finite elemetn analysis in which the loading procedure is simulated and the behaviors of the specimen such as load-displacement curve are estimated. In the course of the evaluation the values $K_ I$, $K_ I1$ and J-integral calculated through recentrly released numerical methods are employed as the reference ones.

• Steel and Composite Structures
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• v.6 no.1
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• pp.33-53
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• 2006

The rotational behaviour of bolted extended end plate beam-to-column connections is evaluated in the context of the component method. The full moment-rotation response is characterized from the force-deformation curve of the individual joint components. The deformability of end plate connections is mostly governed by the bending of the column flange and/or end plate and tension elongation of the bolts. These components form the tension zone of the joint that can be modelled by means of "equivalent T-stubs". A systematic analytical procedure for characterization of the monotonic force-deformation behaviour of individual T-stub connections is proposed. In the framework of the component method, the T-stub is then inserted in the joint spring model to generate the moment-rotation response of the joint. The procedures are validated with the results from an experimental investigation of eight statically loaded extended end plate bolted moment connections carried out at the Delft University of Technology. Because ductility is such an important property in terms of joint performance, particularly in the partial strength joint scenario, special attention is given to this issue.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.12
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• pp.2090-2095
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• 1997

The plane stress fracture toughness for thin aluminum alloy(2024-T3 and 7075-T6) specimens are characterized by using compact-tension (CT) specimens. Anti-buckling plates were fabricated on both sides of the thin CT specimens to prevent the buckling phenomena which caused by the 45.deg. C plastic yielding at the crack tip under the plane stress condition. The plane stress fracture toughnesses determined by three different procedures are compared with each others. The plane stress fracture toughnesses are also compared with a few published values which were determined by using center-cracked panel specimens.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.368-375
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• 2009

This paper describes field installation and load test results performed for three types of micropiles in the process of developing a new micropiling method. Field tests were performed for two conventional types(i.e., micropile reinforced with steel bar and gravity grouting, micropile reinforced with steel bar and steel casing and gravity grouting) and a proposed type(i.e., micropile reinforced with hollow steel pipe wrapped with geotextile-pack and pressurized grouting). The load test results subjected to axial compression and tension and lateral loading conditions are described in this paper. The micropiles were exposed in the air in order to verify the installation quality and curing condition of grouting material via ground excavation. Axial compression and tension test results indicate that the new micropile type provide at least 40% higher bearing capacity than that of conventional types. Based on the examination of exposed piles, it is induced that the proposed method, packed micropile, provides better interlocking between grouts and surrounding soils and increases higher frictional resistance comparing to conventional types.

• Journal of the Korean Chemical Society
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• v.18 no.5
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• pp.354-357
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• 1974

The critical micelle concentration(CMC) of sucrose monostearate is determined between 20 and $40^{\circ}C$, and the effect caused by the addition of sucrose distearate on the CMC is also studied. It is found that, when both of monoester and diester are dissolved, the curve of surface tension of the solution versus the concentration shows a discontinuity at about 40 dyne $cm^{-1}$ of the surface tension. The discontinuity is interpreted as the associate formed between monoester and diester changes its surface orientation at this region.

• Magazine of the Korea Concrete Institute
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• v.8 no.6
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• pp.205-212
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• 1996

This paper presents progressive fracture analysis of concrete using boundary element method and its stabilizing technique. To determine ultimate strength and to predict nonlinear behavior of concrete during progressive crack growth, the modelling of fracture process zone is done based on Dugdale-Barenblatt model with linear tension-softening curve. We regulate displacement and traction boundary integral equation of solids including crack boundary and analyze progressive fracture of concrete beam and compact tension specimen. Also a numerical technique which considers the growth of stress-free crack of concrete during the analysis and removes snapback of postpeak behavior is proposed.

• Journal of the Korean Wood Science and Technology
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• v.31 no.3
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• pp.35-41
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• 2003

The mechanical and physical properties of wood are strongly dependent upon the slope of grain. Specially, tensile strength is more severely affected by the slope of grain. Therefore, tension tests were performed on small thin wood samples made from Pinus radiata with varying the slope of grain. Determining the tensile strength for clear thin wood samples the other variabilities associated with material, size, drying, defects, etc were discarded. Slope of grain was measured by the slope of grain indicator and actual slope of grain was also determined by a protractor. Correlation coefficients between machine measured and actual slope of grain for 40 pieces of 2×20 mm, 300 mm long Pinus radiata were 0.84 for wide face measurement. Results also showed that tensile strength and MOE from stress wave tests decreased with increasing the slope of grain. This study did not establish a relationships for tensile strength and MOE from stress wave with slope of grain. However, the trends of MOEs from stress wave test with both slope of grain are agreed well with Hankinson's equation. Predicted tension strength curve by Hankinson's equation was also agreed well with the experimental data over the range from 0 to 13 degrees for slope of grain.