• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.53.1-56
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• 1999

Using a new dynamic-explicity program SAIT_STAMP the analysis of forming a front door panel is presented. The analysis consists of 7 processes including drawing trimming flanging and springback. From the analysis results it is shown that adaptive refinement scheme and robust trimming algorithm enable SAIT_STAMP to simulate the multi-stage forming of automotive parts with large and complex geometry.

• Transactions of Materials Processing
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• v.12 no.6
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• pp.536-541
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• 2003

In this paper, the rigid-viscoplastic finite element method is employed together with an iteratively force-balancing method to analyze a piercing and trimming process with a spring-attached die in hot former forging. An actual piercing and trimming process with a spring-attached die is investigated in detail and a generalized analysis model is proposed. A multi-stage hot former forging process is simulated under various spring constants. The analyzed results are discussed in order to investigate the effects of spring constants on the metal flow lines and the formed shapes. Then an optimal piercing and trimming process in hot former forging is devised.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.06a
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• pp.49-54
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• 2006

During most of manufacturing processes of auto-body panels, the trimming line should be designed in advance prior to flanging. It is an important task to find a feasible trimming line to obtain a precise final part shape after flanging. This paper proposes a new fast method to find feasible trimming line based on one-step analysis. The basic idea of the one-step analysis is to seek for the nodal positions in the initial blank from the final part, and then the distribution of strain, stress and thickness in the final configuration can be calculated by comparing the nodal position in the initial blank sheet with the one of the final part. The one-step analysis method is able to predict the trimming line before flanging since the desired product shape after flanging can be defined from the final configuration and most of strain paths are simple during the flanging process. Finally, designers can obtain a discrete trimming line from the boundary of the developed meshes after one-step analysis and import it into CAD system in the early design stage. The proposed method has been successfully applied to two basic curve flanging processes demonstrating many advantages.

• Transactions of Materials Processing
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• v.15 no.6 s.87
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• pp.445-452
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• 2006

In most of automobile body panel manufacturing, trimming process is generally performed before flanging. To find feasible trimming line is crucial in obtaining accurate edge profile after flanging. Section-based method develops blank along manually chosen section planes and find trimming line by generating loop of end points. This method suffers from inaccurate results of edge profile. On the other hand, simulation-based method can produce more accurate trimming line by iterative strategy. In this study, new fast simulation-based method to find feasible trimming line is proposed. Finite element inverse method is used to analyze the flanging process because final shape after flanging can be explicitly defined and most of strain paths are simple in flanging. In utilizing finite element inverse method, the main obstacle is the initial guess generation for general mesh. Robust initial guess generation method is developed to handle genera] mesh with very different size and undercut. The new method develops final triangular mesh incrementally onto the drawing tool surface. Also in order to remedy mesh distortion during development, energy minimization technique is utilized. Trimming line is extracted from the outer boundary after finite element inverse method simulation. This method has many advantages since trimming line can be obtained in the early design stage. The developed method is verified by shrink/stretch flange forming and successfully applied to the complex industrial applications such as door outer flanging process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.258-261
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• 2003

In this study, finite element analysis for multi-stage deep drawing process of rectangular configuration with extreme aspect ratio is carried out especially for the blank design. The analysis of rectangular deep drawing process with extreme aspect ratio is likewise very difficult with respect to the design process parameters including the intermediate die profile. In order to solve the difficulties, numerical approach using finite element method is performed in the present analysis and design. A series of experiments for multi-stage rectangular deep drawing process are conducted and the deformed configuration is investigated by comparing with the results of the finite element analysis. Additionally, to minimize amount of removal material after trimming process, finite element simulation is applied for the blank modification. The analysis incorporates brick elements for a rigid-plastic finite element method with an explicit time integration scheme using LS-DYNA3D.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.06a
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• pp.68-71
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• 2006

Traditional section-based method develops blank along section planes and find trimming line by generating loop of end points. This method suffers from inaccurate results for regions with out-of-section motion. In this study, new fast method to find feasible trimming line is proposed. One step FEM is used to analyze the flanging and incremental development method is proposed to handle bad-shaped mesh and undercut part. Also in order to remedy mesh distortion during development, energy minimization technique is utilized. The proposed method is verified by shrink/stretch flange forming and successfully applied to the complex industrial applications such as door outer flanging process.

• Journal of the Korean Society of Costume
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• v.53 no.5
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• pp.111-124
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• 2003

The purpose of this study is to analyze how the women´s fashion with the design elements(silhouette, material, color, detail and trimming) of androgynous image which has appeared on our specialized fashion magazine from 1986 through 2000. As a result of this study I drew the following conclusion. 1. The bon silhouette led the market in the first stage of mid 1980. The wool and leather with the masculine image, cotton and soft material with unisex image were used to express the androgynous image. The dark and mono tone with the masculine image were used a lot in color. In women´s fashion the minimalism style with simple image was expressed escaping from the decoration, in which the detail and trimming was not found as in men´s wear. 2. It showed that more and more feminine image was accepted in the second stage of early 1990. Women´s wear silhouette with the androgynous image has changed from masculine box silhouette boomed in the first stage to hourglass silhouette and slim silhouette. The wool and leather were used a lot as the materials in the first stage but the usage of the cotton with unisex image and soft texture were getting increased. The main colors were the black and the blue but the usage of the white and the red were on the increase showing the range of the use was extending. In the meantime, the detail and trimming were hardly used like in the first stage. 3. In the third stage of the late 1990, the silhouette has changed to slim style. The wool and leather were mainly used as the materials but the cotton and silk were on the increase showing that the materials of the feminine image were used in the women´s fashion with the androgynous image as well as the materials of masculine image. In color, the black and the white of the masculine image were used increasingly by the effect of the minimalism and the usage of the colors were various for the rising frequency of the trend colors usage.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.6 s.177
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• pp.1499-1512
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• 2000

The dynamic explicit finite element method and the static implicit finite element method are applied effectively to analyze total auto-body panel stamping processes, which include the forming stage , the trimming stage and the spring-back stage.\The explicit time integration method has better merits in the forming stage including highly complicated three-dimensional contact conditions. On the contrary, the implicit time integration method is better for analyzing spring-back since the complicated contact conditions are removed and the computing time to get the final static state is short. In this work, brief descriptions of the formulation and the factor study are presented. Further, the simulated results for the total auto-body panel stamping processes are shown and discussed. The formability and the weld line movement in stamping with Tailor Welded Blanks were investigated through QTR-OTR-FRT.

• Proceedings of the Korean Society of Crop Science Conference
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• 2023.04a
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• pp.110-110
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• 2023

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.9
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• pp.875-882
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• 2011

In the present study, the imbalance in the axial-thrust and variation in the volumetric efficiency that occurred during the trimming of impeller diameter were investigated. The present study was focused on low-specific-speed multistage centrifugal pumps with a balancing piston as the balancing mechanism. The effects of impeller trimming on the axial-thrust balance in multistage pumps with horizontal and vertical axes were compared. The results showed that impeller trimming resulted in an additional axial-thrust acting in direction of pump inlet. The axial-thrust imbalance due to impeller trimming was more severe in the vertical-axis pumps than in the horizontal-axis pumps. The rate of increase in the diameter of the balancing piston, which was proportional to the rate of impeller trimming, was evaluated to maintain the axial-thrust balance. Furthermore, a simultaneous increase in the piston length and piston diameter was more effective for reducing the axial-thrust imbalance along with the volumetric efficiency drop.