• Transactions of Materials Processing
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• v.13 no.1
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• pp.90-101
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• 2004

An inverse mosaic method has been proposed to generate an initial blank shape from the final product shape. Differently from the geometric mapping method, the method can handle triangular patches. However, the generated blank shape is strongly dependent on the order of determination of nodes. In order to compensate the dependency error smoothing technique has been also developed. Although the accuracy has been improved greatly compared with the geometrical mapping method, the method has limitation, due to the no incorporation of plasticity theory. Even though the accuracy of the radius vector method is already proved. the method requires initial guess to start the method. In order to compromise the limitation of the present method and the radius vector method, the method has been connected to the radius vector method. The efficiency of the present optimal blank design method has been verified with some chosen examples.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.414-417
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• 2005

Many process parameters have an effect on the auto-body panel forming process. A well-designed blank shape causes the material to flow smoothly, reduces the punch and yields a product with uniform thickness distribution. Therefore, the determination of an initial blank shape plays the important role of saving time and cost in the auto-body panel forming process. For these reasons, some approaches to estimate the initial blank shape have been implemented in this paper, the one-step approach by using a finite element inverse method will be introduced to predict the initial blank shape the developed program is applied to auto-body panel forming.

• Journal of the Korean Society of Safety
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• v.20 no.1 s.69
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• pp.68-74
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• 2005

The objective of the present work is to examine the evaporation shape of deposited droplet on the hot surface. this paper performed the experiments as following conditions: (a) the surface temperature is within the range between $80^{\circ}C$ and $95^{\circ}C$ in the conduction and radiation, (b) droplet diameter is 3.0mm. The results are as follows; while droplet evaporates, droplet's radius is kept changelessly to $70\%$ evaporation time and droplet's shape is kept changelessly after. In case use Constant radius model, about $10\%$ is appearing high than value that time-averaged heat flux applies Inverse heat conduction.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.419-422
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• 2005

Many process parameters have an effect on the auto-body panel forming process. A well-designed blank shape causes the material to flow smoothly, reduces the punch and yields a product with uniform thickness distribution. Therefore, the determination of an initial blank shape plays the important role of saving time and cost in the auto-body panel forming process. For these reasons, some approaches to estimate the initial blank shape have been implemented in this paper, the one-step approach by using a finite element inverse method will be introduced to predict the initial blank shape the developed program is applied to auto-body panel forming.

• Journal of the Korean Data and Information Science Society
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• v.25 no.4
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• pp.903-914
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• 2014

The inverse Weibull distribution has been proposed as a model in the analysis of life testing data. Also, inverse Weibull distribution has been recently derived as a suitable model to describe degradation phenomena of mechanical components such as the dynamic components (pistons, crankshaft, etc.) of diesel engines. In this paper, we derive the approximate maximum likelihood estimators of the scale parameter and the shape parameter in the inverse Weibull distribution under multiply type-II censoring. We also develop four modified empirical distribution function (EDF) type tests for the inverse Weibull or extreme value distribution based on multiply type-II censored samples. We also propose modified normalized sample Lorenz curve plot and new test statistic.

• Transactions of Materials Processing
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• v.22 no.6
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• pp.328-333
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• 2013

The current study aims to determine the limit strains more accurately and reasonably when producing a forming limit curve (FLC) from experiments. The international standard ISO 12004-2 in its recent version (2008) states that the limit major strain should be determined by using the best-fit inverse second-order parabola through the experimental strain distribution. However, in cases where fracture does not occur at the center of the specimen, due to insufficient lubrication, the inverse parabola does not give a realistic fit because of its intrinsic symmetry in shape. In this study it is demonstrated that an inverse quartic function can give a much better fit than an inverse parabola in almost all FLC test samples showing asymmetric strain distributions. Using a quartic fit creates more reliable FLCs.

• Transactions of Materials Processing
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• v.15 no.6 s.87
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• pp.459-466
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• 2006

Trimming line design plays an important role in obtaining accurate edge profile after flanging. Compared to the traditional section-based method, simulation-based method can produce more accurate trimming line by considering deformation mechanics. Recently, the use of a finite element inverse method is proposed to obtain optimal trimming line. By analyzing flanging inversely from the final mesh after flanging, trimming line can be obtained from initial mesh on the drawing die surface. Initial guess generation fer finite element inverse method is obtained by developing the final mesh onto drawing tool mesh. Incremental development method is adopted to handle irregular mesh with various size and undercut. In this study, improved incremental development algorithm to handle complex shape is suggested. When developing the final mesh layer by layer, the algorithm which can define the development sequence and the position of developing nodes is thoroughly described. Flanging of front fender is analyzed to demonstrate the effectiveness of the present method. By using section-based trimming line and simulation-based trimming line, incremental finite element simulations are carried out. In comparison with experiment, it is clearly shown that the present method yields more accurate edge profile than section-based method.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.1929-1930
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• 2006

Human like robot arm posture for grasping by considering the shape of the target object is quite a challenge in the field of robotics. In this paper, an optimized grasp posture with respect to the shape of the object considering the wrist joint angle and elbow elevation angle, in order to verify that the grasp posture is human like has been proposed. Given a target object, the candidates for grasp are computed by the method described in this paper. For each candidate, the closed loop inverse kinematics has been solved for the corresponding hand position and orientation. From the obtained joint angles through inverse kinematics, the elbow elevation angle has been computed and compared with the elbow elevation angle obtained through human movement data by the characteristic equation. After considering all the candidates, the hand position and orientation with minimum wrist joint and difference in elbow elevation angles has been utilized as the optimized grasp posture. Simulation results are presented.

• Journal of Welding and Joining
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• v.27 no.2
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• pp.32-37
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• 2009

In shipyard, plate forming is widely used to form the ship hull plate in various shapes. Line heating method by using a flame torch is one of the major shipbuilding processes carried out by skilled workers. Since the forming characteristics depend upon their experiences in manual forming, there are much variations between products and difficulties in communication between engineers and workers. Hence, it needs to develop an automatic forming system which can not only reduce the working time and rework costs but also improve the working environment and hull forming productivity. One of the final goals of plate forming automation is to form a target shape from the initial plate automatically. For automated plate forming, it is required to determine where and how to heat on the plate. To realize this procedure, the inverse problem should be first solved and the effect of curvature shape formed at the heating path should be investigated. In this study, the inverse problem was solved by geometrical approach using the relationship between bending angle and radius of curvature of the curved shape. In addition, experiments of two-dimensional plate forming were performed with the distance-based method considering the curved bending with curvature. The result of the formed shape agreed considerably well with the target shape.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.315-318
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• 1995

The optimum design problem of a coat-hanger die is solved by the inverse formulation. The flow in the die is analyzed using three-dimensional model. The new model for the manifold geometry is developed for the inverse formulation. The inverse problem for the optimum die geometry is formed as the optimization problem whose objective function is the linear combination of the square sum of pressure gradient deviation at die exit and the penalty function relating to the measure of non-smoothness of solution. From the several iterative solutions of the optimization problem, the optimum solution can be obtained automatically while producing the uniform flow rate distribution at die exit.