• Transactions of the Korean Society of Mechanical Engineers
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• v.6 no.3
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• pp.232-238
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• 1982

The behavior of corner crack propagation by unidirectional plane bending fatigue was investigated in the butt welded joints of SS41 and SM50 steel plates including an edge through-thickness notch. The properties of fatigue crack propagation were inspected in the weld metal, heat-affected zone, and base metal of the welded joints. Main results obtained are as follows; (1) When a plate with an edge through-thickness notch is loaded by plane bending fatigue in indirection, the 2 variant corner cracks on the upper and lower edge of the plate are initiated and propagated respectively from the notch. (2) In case of a specimen containing a corner crack, it is more reasonable to estimate the crack propagation rate by area of fracture surface than by crack surface length. (3) The rate of fatigue crack propagation becomes faster in the following order; weld metal, heat-affected zone, and base metal. (4) The specimen including reinforcement shape is rapidly failed throughout bond due to effect of its shape when the repeated load exceeds a certain cycle.

• Journal of the Korea Institute of Building Construction
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• v.8 no.2
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• pp.113-119
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• 2008

Recently, fiber reinforced polymers(FRP) composite materials are used extensively in the rehabilitation of concrete structural members. A main application is to wrap beams and columns using the continuous fibers sheets to improve their strength and ductility. The corner chamfering affects significantly the performance of the continuous fibers sheets, and could lead to environmental problem with waste and dust. The main purpose of this paper is to verify the effect of corner conditions on the strength of the continuous fiber sheets, and to introduce new attached components which can avoid environmental problem. A total of 15 specimens were tested and carefully checked for three types of continuous fiber sheets(carbon, glass, and aramid) and three types of corner conditions(non-chamfering, chamfering, and device attaching). It is proved that the devices proposed in this research have some capabilities to use for RC member. But additional research will be needed for commercializing.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.3 s.147
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• pp.331-339
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• 2006

The objective of this paper is to calculate the fatigue strength for upper deck hatch corner insert plate of large container carriers without wave load analysis and global finite element analysis at the initial design stage. Wave load analysis and global F.E. analysis for three container carriers have been performed by GL(Germanischer Lloyd) procedure to propose the equation for hatch corner stress range which is the important factor in fatigue strength calculation. Considering the restraining effect of bulkhead, three types of equation, that is, single tight bulkhead, double tight bulkhead and support bulkhead have been proposed. Using the proposed equations, a simplified fatigue analysis based on GL rules has been performed for two container carriers of which fatigue strength analysis was carried out by GL. From the comparison between fatigue strength result of using the proposed equations and that of GL, it has been found that proposed stress range equations are useful for scantling of upper deck hatch corner insert plates for over 8,000 TEU class container carriers.

• Transactions of Materials Processing
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• v.19 no.8
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• pp.447-451
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• 2010

In this paper, a useful die system for warm plate forging of a large axle housing of heavy-duty trucks is presented. A die system composed of material flow guide pin as well as upper die and lower die is proposed to reduce the inherent thickness reduction along the bent corner of the product which deteriorates structural strength and fatigue life in its service. The role of the pin assembled in the upper die is to prevent formation of sharp corner in early forming stage and to supply material in the lower die cavity sufficient enough to thicken the bent corner at the final stroke. The mechanism of the die system is given and its effect on corner thickness of the product is revealed by two-dimensional finite element analysis under plain strain assumption. Three-dimensional finite element solutions are also given to verify validity of the two dimensional approach and to show the mechanics of the die system in detail. The die system has been successfully applied to manufacturing the axle housing of heavy-duty trucks.

• Wind and Structures
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• v.36 no.2
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• pp.105-120
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• 2023

The present study is performed to find the effect of corner recession on a square plan-shaped tall building. A series of numerical simulations have been carried out to find the two orthogonal wind force coefficients on various model configurations using Computational Fluid Dynamics (CFD). Numerical analyses are performed by using ANSYS-CFX (k-ℇ turbulence model) considering the length scale of 1:300. The study is performed for 0° to 360° wind angle of attack. The CFD data thus generated is utilised to fit parametric equations to predict alongwind and crosswind force coefficients, C_fx and C_fy. The precision of the parametric equations is validated by employing a wind tunnel study for the 40% corner recession model, and an excellent match is observed. Upon satisfactory validation, the parametric equations are further used to carry out multiobjective optimization considering two orthogonal force coefficients. Pareto optimal design results are presented to propose suitable percentages of corner recession for the study building. The optimization is based on reducing the alongwind and crosswind forces simultaneously to enhance the aerodynamic performance of the building.

• Korean Journal of Metals and Materials
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• v.46 no.6
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• pp.329-337
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• 2008

During the continuous casting of boron-bearing steel, the corner cracks on the slab are formed by deformation with low strain rate and rapid cooling at the unbending temperature within the range of 800- $1000^{\circ}C$. Especially, the rapid cooling in the corner of slab during the continuous casting leads to as corner cracking. Therefore, in this study, the hot tensile tests applied to the different cooling rates were taken into account in order to study the effect of cooling rate on the hot ductility of boron-bearing steel. The results revealed that increasing cooling rate deteriorate the hot ductility of boron- bearing steel. Rapid decreasing of the hot ductility is caused by formation of a film-like ferrite and precipitate at the austenite grain boundaries. The morphology of the precipitates in the boron-bearing steel was monitored by PTA (Particle Tracking Autoradiography) and TEM, we observed MnS and BN compound and their morphology was quite different depending on the cooling rates. When the cooling rate is increased, rodshape MnS and BN precipitates can be formed along the austenite grain boundaries. It can cause that weakening the boundary region and decreasing the hot ductility of boron-bearing steel.

• Geotechnical Engineering
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• v.14 no.3
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• pp.73-94
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• 1998

In the present study, a method of the three-dimensional limit equilibrium stability analysis of shape of the potential failure wedge for the concave-shaped excavation corner is assumed on the basis of the results of the FLACSU program analysis. Estimation of the three-dimensional seepage forces expected to act on the failure wedge is made by solving the three-dimensional continuity equation of flow with appropriate boundary conditions. By using the proposed method of three-dimensional stability analysis of the concave-shaped excavation corner, a parametric study is performed to examine the reinforcement effect of skew soil nailing system, range of the efficient skew angles and seepage effect on the overall stability. Also examined is the effect of an existence of the right-angled excavation corner on three-dimensional deflection behaviors of the convex-shaped skew soil nailing walls. The results of analyses of the convexshaped excavation corner with skew soil nailing system is further included to illustrate the effects of various design parameters for typical patterns of skew nails reinforcement system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.791-796
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• 2003

Some basic guidelines for changing non-uniform boundary condition in an acoustically small cavity are presented. In this paper, modal summation technique is used to represent inside sound field. From this formulation, corner effect is defined and proposed. The corner in a cavity is good position for changing boundary condition effectively. Impedance circle with same absorption coefficient is defined to find appropriate impedance of absorptive material for better noise control performance.

• Journal of Industrial Technology
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• v.22 no.A
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• pp.185-192
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• 2002

The performance of old and the new concrete construction depends upon bond strength between old and the new concrete. Current adhesive and strength measurement method ignores the effect of stress concentration from shape of specimens. Therefore, this research calculates stress concentration coefficient as the ratio of drilling depth to drilling diameter($h_s/D$), the ratio of overlay thickness to drilling diameter($h_0/D$), the ratio of steel disk thickness to drilling diameter(t/D), the ratio of overlay elastic modulus to substrate modulus($E_1/E_0$), the distance from core to corner border(L_$_{corner}$) and the distance between cores(L_$_{coic}$) vary. The finite element method is adapted to analysis The results from 'the F.E.M analysis are as follows. The stress concentration effects can be minimized when the ratio of drilling depth to drilling diameter($h_s/D$) is 0.20~0.25, the elastic modulus ratio($E_1/E_0$) is 06~1.0, and the ratio of steel disk thickness to drilling diameter(t/D) is 3.0. The overlay thickness, the distance from specimens to corner border(L_$_{corner}$), the distance between cores(L_$_{coic}$) almost do not affect to the stress concentration.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.3
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• pp.182-188
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• 2001

An experiment is carried out to investigate the characteristics of blanking for copper alloy C194 (t=0.254mm), a kind of IC lead frame material. By varying clearance between die and punch, the shapes of shear profile are examined. Finite element analysis with element deletion algorithm for ductile fracture mode is also carried out to study the effect of clearance theoretically and to compare with experimental results. The rectangular shape specimen with four different corner radius is used to study the characteristics of blanking for straight side and corner region simultaneously. As the result, the ratios measured from the experiment of roll over, burnish, and fracture zone based on intial blank thickness are compared with those of FE analysis. Both experiment and FE analysis show that the amount of roll over and fracture is increased as the clearance increases. It has been found that larger clearance is required than that of straight region when the radius of corner is less than thickness of blank, in order to maintain same quality of shear profile at the corner region.