• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.11 s.170
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• pp.2096-2101
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• 1999

This paper presents the effect of shape of external corrosion in pipeline on failure prediction by using numerical simulation. The numerical study for the pipeline failure analysis is based on the FEM(Finite Element Method) with an elastic-plastic and large-deformation analysis. The predicted failure stress assessed for the simulated corrosion defects having different corroded shapes along the pipeline axis are compared with those by methods specified in ANSl/ASME B31G code and a modified B31G code.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.546-551
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• 1997

In sheet metal forming, since the surface area of workpiece is apparently larger than the volume of it, the surface condition of the sheet metal is much varied. The formability of sheet metal is decided by the forming limit and the macroscopic suface defect as like fracture and wrinkle, and microscopic asponent, The factors affected in forming limit are stain herdening exponent, strain-rate scnsitivity exponent, anisotropic coefficient. The increasing of surface roughness is decresed the forming limit curve. It is known that the greater plastic deformation the more surface roughness by Kienzle, Osadaka. The purpose of this study is to investigate the influences of surface roughness in a uniaxial tension and the traperzoidal-shaped box drawing.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1660-1665
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• 2003

On this study, we improved the efficiency applying algorithm that is repeatedly using orthogonal array in discrete design space and filling a defect of gradient method in continuous design space. we showed optimal ply angle that maximized 1st natural frequency of CFRP laminated composite cantilever plate by each aspect ratio. A finite element analysis on the CFRP laminated composite cantilever plate using orthogonal array is carried out, and the results are compared with those obtained by modal testing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.84-85
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• 2005

Dislocations are often found at Shallow Trench Isolation (STI) process after repeated thermal cycles. The residual stress after STI process often leads defect like dislocation by post STI thermo-mechanical stress. Thermo-mechanical stress induced by STI process is difficult to remove perfectly by plastic deformation at previous thermal cycles. Embedded flash memory process is very weak in terms of post STI thermo-mechanical stress, because it requires more oxidation steps than other devices. Therefore, dislocation-free flash process should be optimized.

• Journal of Welding and Joining
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• v.17 no.4
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• pp.76-84
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• 1999

The residual stress generated when the steel plates were produced, did not influence on the out-of-plane deformation and residual stress generated by welding. When the initial deflection shape was a concave(Type I), the out-of-plane deformation became the same shape as that of the initial deflection and its magnitude became small. When the initial deflection made a winding in the welding direction(Type III), the out-of-plane deformation became large in the plate width. The initial deflection shape did not influence on residual stress and plastic strain produced by welding.

• Transactions of Materials Processing
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• v.12 no.4
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• pp.340-347
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• 2003

In the rigid-plastic finite element simulation of hot forging processes using hexahedral mesh, remeshing of a flash is important for design and control of the process to obtain desirable defect-free products. The mesh compression method is a remeshing technique which enables the construction of an effective hexahedral mesh in the flash. However, because the mesh is distorted during the compression procedure of the mesh compression method, when it is used in resuming the analysis, it causes discretization error and decreases the conversance rate. Therefore, mesh smoothing is necessary to improve the mesh quality. In this study, several geometric mesh smoothing techniques and optimization techniques are introduced and modified to improve mesh quality. Then, the most adaptive technique is recommended for the mesh compression method.

• Journal of Veterinary Clinics
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• v.19 no.4
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• pp.440-442
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• 2002

A fourteen-year-old mongrel female dog that was 22 kg and had two large mammary tumor lesions was admitted to the Animal Teaching Hospital of Chonbuk National University. Two large mammary tumor lesions were observed in the right caudal thoracic and the left inguinal mammary glands, which were sized 6 cm and 5 cm in diameter, respectively. These tumor lesions were removed by block mastectomy, then large skin defect of 7 cm diameter in caudal abdominal wall were recoverd by classic Z-plasty in both medial thigh. Classic Z-plasty was designed with 60 in angle and, with 6 cm in length of central limb in right medial thigh and 4 cm in left, respectively. This patient had been recoverd to normal gait and behavior at 20 days after the plastic operation.

• The Korean Journal of Pain
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• v.6 no.2
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• pp.261-264
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• 1993

A 26 year old male patient had admitted to the department of plastic surgery for the treatment of skin defect of forearm and spastic contracture of right hand, attributable to burn injury following carbon monoxide intoxication. After receiving skin graft the patients tenotomy of flexor tendons, the patients was consulted to pain clinic for further evaluation and treatment of allodynia, hyperalgesia, and hyperpathia with marked emotional insufficiency. The patient was treated with stellate ganglion blocks, intermittent or continuous epidural blocks, and intermittent brachial plexus blocks for 3 months. with this treatment the patient's pain level improved to(VAS 10 to 4~5) and was discharged. The patient was readmitted 3 months later, due to the aggrzvation of pain. Brachial plexus blocks were given again by interscalene, supraclavicular, or axillary route, sometimes using a catheter, together with cervical epidural blocks. Tricyclic antidepressant was also prescribed. The results were remarkably good(VAS 2~3) and the patient did not require any further analgesic medication.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.428-431
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• 2005

This paper describes the process design for hot forging of bearing hub. Forging processes of bearing hub are simulated using the rigid-plastic finite element method. In the process called closed die forging without flash, the design of blocker geometry is of critical importance. Forging processes designs are take advantage of computer aided Process planning and experts. But that is difficult to predict metal flow line. So the preform is designed by the expert, and modified through predict metal flow line by CAE. This paper is to approach preform design considered defect such as metal flow and unfitting etc. at the finisher process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.8
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• pp.2458-2467
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• 1996

The rigid-plastic finite element analysis was performed for analysis of ofhot forging and cold sizing of a bevel gear. Two dimensional analysis was carried out to investigate the defect occurrence on vertical symmetric planes during hot forging and three dimensional analysis was to understand the filling behavior on horizontal planes during cold sizing. The involute curve of a tooth was approximated by a circle for convenience in the present analysis. In order to estimate the elastic deformation of the gear and dies during cold sizing, linear elastic finite element analysis was performed. Results of the analysis can be used to predict grain flows and strength distributions in the forged gear, and to design dies and an appropriate preform for the cold sizing.