• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.1
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• pp.21-29
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• 2016

To overcome the large ring gear manufacturing problems seen in slewing bearings and girth gears, pin gear drive units have been developed. Among them, a novel slewing bearing with an internal pinwheel gear set (i-PGS) is introduced in this paper. First, we consider the exact cam pinion profile of i-PGS with the introduction of a profile shift coefficient. Furthermore, a new root relief profile modification for the i-PGS cam pinion is presented. Then, the contact stresses are investigated to determine the characteristics of the surface fatigue by varying the shape design parameters. The results show that the contact stresses of i-PGS can be reduced significantly by increasing the profile shift coefficient. In addition, the contact ratio, a measure of teeth overlapping action, decreases with the decrease of the allowable pressure angle.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.4 s.97
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• pp.122-128
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• 1999

Bolted joint assembly for nuclear power plants consists of various components : cover plate, retainer plate, manway flange, gasket and stud bolts/nuts. To guarantee the soundness of the joint, it is important to prevent leakage through the gasket and reduce the stress concentration factor at the thread root. In this paper, Submodeling technique for the finite element method is proposed to accurately compute three dimensional contact stresses which govern the sealing performance and the maximum contact stresses at the threads root. For verification of global solutions used as boundary conditions of submodel solution, the stresses on the cover plate and the manway flange are measured by strain gages when internal pressure is applied to the bolted joint assembly. The numerical results are compared with the experimental results.

• Bulletin of the Society of Naval Architects of Korea
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• v.7 no.2
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• pp.27-40
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• 1970

The distribution of stress and strain in elastic stages is investigated by the experiments of two dimensional photoelastic coating and Moire fringe method. Center block type and cover plate type of fillet welds are used as specimens in the test. The results are as follows. 1) Center block type gets less uniform stress distribution than cover plate type. And its stress concentration factor, especially at root, is larger than that at toe. 2) When main plate and cover plate closely contact and it cause friction, stress concentration decreases more than that in case of slit. That is because stress can be transmitted on the contact surface. 3) When slit is made, the outside of fillet gets more stress than the inside of it. 4) While the plastic strain distribution of center block type reaches the maximum at root and differs very slightly from that under lower loading, the plastic strain distribution of cover plate type is inclined to get the maximum at the outside of fillet rather than at root. 5) When the plastic strain value of cover plate type is compared with that of center block type at toe and root, the relations between the former and the latter shows root<toe and root>toe. 6) Because stress distribution becomes changed according to loading, fracture angle cannot be estimated by the peaks of elastic stress distribution. 7) The strain distribution just before fracture can be found by Moire fringe method.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.2
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• pp.59-64
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• 2001

The distribution of current in the conductors influenced by the armature geometry and velocity is an important parameter for determining performance of an electromagnetic launcher(EML). the electric current in the early launching stage tends to flow on the outer surfaces of the conductors, resulting in very high local electric current density. However, the tendency for current to concentrate on the surface is driven by the velocity skin effect later in launching stage. The high current density produces high local heating and, consequently, increases armature wear which causes several defects on EML system. This paper investigates the effects of rail/armature geometry on current density distribution, launcher inductance gradient (L'), and contact force. Three geometrical parameters are used here to characterize the railgun system. These are the ratio of contact length to root length, relative position of contact leading edge to root trailing edge, and the ratio of rail overhang to the rail height. The distribution of current density, L', contact force between various configurations of the armature and the rail are analyzed and compared by using the EMAP3D program.

• Computers and Concrete
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• v.31 no.2
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• pp.163-171
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• 2023

Face gear transmission is widely used in aerospace shunt-confluence transmission system. Tooth wear is one of the main factors affecting its bearing transmission performance. Furthermore, the installation errors of face gear are inevitable. In order to study the wear mechanism of face gear tooth surface with installation errors, based on tooth contact analysis numerical method and Archard wear theory, the UMESHMOTION subroutine in ABAQUS is developed.Combining with Arbitrary Lagrangian-Eulerian adaptive mesh technology, the finite element mesh wear model of abraded face gear pair is established.The preprocessing conditions are set to generate the inp files.Then,the inp files for each corner are imported and batch processed in ABAQUS.The loading tooth contact problem at each rotation angle is solved and the load distribution coefficient among gear tooth, tooth root bending stress, tooth surface contact stress and loaded transmission error are obtained. Results show that the tooth root wear is the most serious and the wear at the pitch cone is close to 0.The wear law of tooth surface along tooth width direction is convex parabola and the wear law along tooth height direction is concave parabola.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.5
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• pp.85-95
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• 2001

This study proposed a technique for inverse problem, linear approximation of contact position and loading in single and double meshing of spiral bevel gear , using 2-dimension model considered near the tooth by root stress. Determine root stress is carried out far the gear tooth by finite element method and boundary element method. Boundary element discretization near contact point is carefully performed to keep high computational accuracy. And from those estimated results, the comparing estimate value with boundary element method value was discussed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.2
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• pp.232-240
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• 2012

This study proposed efficient method of singular value for inverse problem, linear approximation of contact position and loading in single and double meshing of transmission contact element, using 2-dimension model considered near the tooth by root stress. Determination of root stress is carried out for the gear tooth by finite element method and boundary element method. Boundary element discretization near contact point is carefully performed to keep high computational accuracy. The predicted results of boundary element method are good accordance with that of finite element method.

• Structural Engineering and Mechanics
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• v.6 no.4
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• pp.363-375
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• 1998

The stiffness matrix of a two-dimensional contact surface element is deduced from the principle of virtual work. The incremental loading procedure used is controlled by displacement and stress. Special potential contact elements are used to avoid the need to rearrange the FEM mesh due to variations of the contact surface as contact develops. Published results are used to validate the method, which is then applied to a turbine to solve the contact problem between the blade root and rotor in the region in which a 'push fit' connects the blade to its rotor.

• Korean Journal of Medicinal Crop Science
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• v.12 no.2
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• pp.118-122
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• 2004

We have investigated that a couple of soft ferrite ceramic powders having a spinal structure have shown the effect on growth and secondary metabolites production of some medicinal plants cultured in vitro. The addition of the ceramic powders as bare state to culture medium has stimulated the growth of Achyranthes japonica callus and plantlet, adventitious root of Hyoscyamus niger and Platycodon grandiflorum hairy root about 65, 75, 150 and 50%, respectively. Whereas Centella asiatica callus and plantlet, Scopolia parviflora hairy root, and Hyoscyamus albus adventitious root were not affected markedly. Moreover, the ceramic powder has enhanced the growth of H. niger adventitious roots even under conditions of irradiating alone without any direct contact between ceramic powder and media. Based on growth stimulation effect, the ceramic powders have enhanced the gross production of tropane alkaloid in H. niger adventitious root, and polyacetylene in P. grandiflorum hairy root about 35 and 30%, respectively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.6
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• pp.1784-1797
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• 1996

The disk/blade assembly of a turbine engine is made in the shape of a dovetail type or a fir-tree type. Since disk fillet regions or contact surfaces undergo high stress comcentration, fatigue cracks frequentrly occur in the disk/blade assembly. Therefore, it is necessary to analyze the stress distributions in the fir-tree type disk/balde assembly and predict the region of fatigue failure. The stress distributions of the disk/blade assembly were investigated by using the photoelastic method and the finite element method. Two dimensional photoelastic techniques were used to investigate the stress distributions of contact surfaces and fillet regions. TH stress distributions were obtained by the shear-difference method and were compared to the finite element results. It was found that maximum tensile stresses were higher in the fillet region thatn in the contact surfaces of the fir-tree models. The finite element results showed good agreement with the experimental results.