• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.352-356
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• 2007

In this study, a rigid-plastic finite element method is applied to simulating a ring rolling process of the inner race cage of a constant velocity joint for the passengers' cars. The ring rolling process is mathematically modeled by several assumptions. The defect formation at the side ends is predicted in detail. The predictions are compared with the experiments and a good agreement is observed in terms of deformed shape.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.2
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• pp.65-70
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• 2003

In this study, researchers developed the estimative algorithm for artificial defect in semiconductor packages and performed it by pattern recognition technology. For this purpose, the estimative algorithm was included that researchers made software with MATLAB. The software consists of some procedures including ultrasonic image acquisition, equalization filtering, Self-Organizing Map and Backpropagation Neural Network. Self-organizing Map and Backpropagation Neural Network are belong to methods of Neural Networks. And the pattern recognition technology has applied to classify three kinds of detective patterns in semiconductor packages : Crack, Delamination and Normal. According to the results, we were confirmed that estimative algerian was provided the recognition rates of 75.7% (for Crack) and 83.4% (for Delamination) and 87.2 % (for Normal).

• Transactions of Materials Processing
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• v.15 no.4 s.85
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• pp.289-294
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• 2006

To reduce automobile parts weight, TWB(tailored welded blank) forming is widely used in panel forming. But products used TWB forming process have many defect, wrinkle, crack and springback. So study of TWB forming process character is very important. In this study one of the current problems of TWB forming was analyzed, especially for the try-out process of inner door panel without frame. A comparison was made between actual measurements and prediction of forming analysis for formability and springback. Also a new analysis die model which have additional plane on die surface was proposed to correct result of forming analysis. This proposed method overcomes the difference for TWB forming result between try-out and analysis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.313-316
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• 1995

In this study, in case the lead sheath of XLPE cable (radius : 15cm, inner conductor radius : 5cm, insulation paper raidius : 6cm, dc voltage : 1MV) is harmed, so that breakdown process by inhomogeneous eletric field is simulated with Finite Element Method. The result of simulation showed that defect of lead sheath layer caused breakdown.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.6
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• pp.650-657
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• 2001

This paper explains the process of designing a shielded encircling remote field eddy current (RFEC) probe to inspect nuclear fuel cladding tubes and investigates resulting signal characteristics. To force electromagnetic energy from exciter coil to penetrate into the tube, exciter coil is shielded outside by laminations of iron insulated electrically from each other. Effects of shielding and the proper operating frequency are studied by the finite element analysis and the location for sensor coil is decided. However, numerically simulated signals using the designed probe do not clearly show the defect indication when the sensor passes a defect and the other indication appeared as the exciter passes the defect is affected by the shape of shielding structure, which demonstrates that the sensor is directly affected by exciter fields. For this reason, the sensor is also shielded outside and this shielding dramatically improves signal characteristics. Numerical modeling with the finally designed probe shows very similar signal characteristics to those of inner diameter RFEC probe. That is, phase signals show almost equal sensitivity to inner diameter and outer diameter defects and the linear relationship between phase signal strength and defect depth is observed.

• Archives of Plastic Surgery
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• v.35 no.6
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• pp.735-738
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• 2008

Purpose: Intraosseous hemangiomas are rare and account for fewer than 1% of all bone tumors. The site that is most commonly involved are the vertebral column and the skull. Within the facial skeleton, hemangiomas can occur in the mandible, maxilla, the nasal bones, and rarely the zygoma. Methods: We report a case of an intraosseous hemangioma of the zygoma in a 49-year-old male. The patient had a slow growing hard mass in the left zygoma, which had been present for 8 years. Other than the cosmetic deformity, the patient experienced no pain and did not have any problem. He had no history of trauma in that area and no ocular symptoms. Preoperative computed tomography showed a trabeculated mass arising from the body of the left zygoma. The mass was surgically removed without having to reconstruct the bone defect by spairing the inner cortex. Results: Histopatholgical examination indicated a cavernous hemangioma. After 4 months of follow up, no functional and cosmetic impairment was identified. The patient was satisfied with the result. Conclusion: An intraosseous hemangioma of the zygoma can be treated with total surgical excision with preservation of the inner cortex, thus eliminating the need for reconstruction of bone defect.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.5
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• pp.423-428
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• 2010

In this paper, we analyzed the characteristics of thermal deformation of the TPS which is a core part of engine in vehicle by measuring out-of-plane deformation using ESP!. Inspection area of a test piece was minimized to 5 cm by 5 cm by using a high resolution CCD and a zoom lens. 4-step phase shifting method was used along with phase unwrapping algorithm to get a continuous phase map, configurations and deformations were displayed as 3D images. When heating the test pieces while maintaining the temperature at about $70^{\circ}C$, the out-of-plane deformations were measured. The results showed that a test piece with longer distance traveled tends to show larger thermal deformation, we could observes a convex shaped deformation on the surface. The inner defect sample, we could monitor discontinuous pattern phase map, and a concave shaped deformation on the surface.

• Journal of Korea Multimedia Society
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• v.5 no.4
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• pp.426-433
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• 2002

In this paper, we have studied the images which have been reconstructed by using combination of images acquired by the variation of operating frequency. When inner images have been reconstructed, they have been superposed by the surface state effect. In this case, the images of the phase object can be enhanced by the contrast of inner images. In this experiment, there are two kinds of specimens, one is a reference block haying 1/4T, 1/2T, 3/4T side drilled holes as main run piping material 111 the steam generator in NPP(Neuclear Power Plant)s and the another is a part of a hemisphere type specimen having about 1-2㎜ distance gap. It has been shown that the two results of defect shapes have better than before in this processing and phase contrast grow about twice. And we have constructed the acoustic microscope by using a quadrature detector that enables to acquire the amplitude and phase of the reflected signal simultaneously Further more ore have studied the reconstruction method of the amplitude and phase images and the enhancement method of the defect images contrast.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.3
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• pp.191-199
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• 2000

In this paper, a numerical analysis using the finite element method (FEM) is presented which models the eddy current testing (ECT) of tubes with 3-dimensional defects. For the description of 3-dimensional eddy current problems, the governing equation is derived from the Maxwell's equations. The 3-dimensional FEM formulation with hexahedral elements is carried out using the Galerkin weighted residual method. The INCONEL 600 steam generator tube with inner and outer diameter defects is adopted for the numerical analysis, and the ECT signal, which is the trajectory of the probe impedance, is calculated. For the verification of the numerical analysis method, results of numerical calculations and experiments are compared and they show good agreements. Based on this verification, several defect signals are predicted and their characteristics are investigated with the variation in the defect depth and the circumferential angle of the defect.

• Archives of Craniofacial Surgery
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• v.19 no.2
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• pp.94-101
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• 2018

Background: Atrophy of muscle and fat often contributes to temporal hollowing after pterional craniotomy. However, the main cause is from the bony defect. Several methods to prevent temporal hollowing have been introduced, all with specific limitations. Autologous bone grafts are most ideal for cranial defect reconstruction. The authors investigated the effectiveness of bony defect coverage and temporal augmentation using pterional craniotomy bone flap. Methods: This study was conducted in 100 patients who underwent brain tumor excision through pterional approach from 2015 to 2016. Group 1 underwent pterional craniotomy with temporal augmentation and group 2 without temporal augmentation. In group 1, after splitting the calvarial bone at the diploic space, the inner table was used for covering the bone defect and as an onlay graft for temporal augmentation. The outcome is evaluated by computed tomography at 1-year follow-up. Results: The mean operative time for temporal augmentation was 45 minutes. The mean follow-up was 12 months. The ratio of temporal thickness of operated side to non-operated side was 0.99 in group 1 and 0.44 in group 2, which was statistically different. The mean visual analogue scale score was 1.77 in group 1 and 6.85 in group 2. Conclusion: This study demonstrated a surgical technique using autologous bone graft for successfully preventing the temporal hollowing and improved patient satisfaction.