• 월간 기계설비
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• no.11 s.220
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• pp.44-47
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• 2008

많은 난관을 극복하고 조기착공에 성공한 후에, 우선적으로 고려할 사항은 주공정(Crtical Path) 을 관리하는 것이다. 주공정(critical Path)의 초기 작업에 필요한 자재, 장비, 인원의 준비를 재점검하고 하도급추진을 하는 한편, 계약서상의 요구조건, 승인사항에 미흡한 점이 없는지를 검토하고 보완한다. 계약서상의 요구사항을 미비하거나 무시했을 경우, 반드시 그에 상응하는 경제적 대가를 치루어야 한다는 것을 명심해야 한다. 시공을 하기 위해서는 자재승인 후 작업도면(Working Drawing/ Construction Drawing/ Shop Drawing)의 승인을 받고, 작업방법(Method Statement)을 제출하고, 설명화 Presentation) 및 시험시공(Demonstration 또는 Mockup)을 거쳐 감리자의 시공허락을 받아야 하며 각종 Test를 통해 품질관리를 실행해야 한다. 시공지는 시방서에서 요구하는 품질이 보장되는 범위 내에서, 최대한 공기를 단축할 수 있도록 공사초기부터 노력을 해야 하며, 공사의 모든 과정에서 항상 claim 여부, 공기내 준공, 하자 Zero, 최단 시일 내에 최대의 기성취하에 역점을 두고, 이에 장애요인을 해결하는 것으로 공사를 진행해야 한다.

• Transactions of Materials Processing
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• v.10 no.3
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• pp.235-245
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• 2001

Deep drawing process, one of sheet metal forming methods, is very useful in the industrial field because of its efficiency The deep drawing is affected by many process variables, such as blank shapes, shape radii of the punch and die, formability of materials and so on. Especially, blank shape is very important formability factor. In this study, in order to investigate the effects of blank shape, we suggested three kinds of blank shapes and examined friction test about three conditions. We measured punch load distribution according to punch stroke under the conditions of each punch and die shape radii and observed punch load of elliptical cup forming.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1995.03a
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• pp.147-154
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• 1995

In this paper, a computer-aided design system for axisymmetric deep drawing process will be described. An approach to the system is based on the knowledge based system. The system has been written in AutoLISP with personal computer. The system is composed of four main modules, such as input , geometrical design, test & rectification and user modification . The system which aids designer provides powerful capabilities for the design of axisymmetric deep drawing process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.08a
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• pp.137-144
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• 2004

The drawbead is one of the most important factors in sheet metal forming for automotive parts. So clarifying the friction characteristics between sheets and drawbead is essential to improve the formability of sheet metal. Therefore in this study, drawbead friction test was performed at circular shape bead and rectangular shape bead. The results show that the tendency of drawing force for rectangular bead is nearly similar with circular bead and the drawing force is nearly proportional to friction coefficient.

• Transactions of Materials Processing
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• v.11 no.5
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• pp.394-404
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• 2002

The drawbead model for a three-dimensional a finite element analysis of sheet metal forming processes is developed. The mathematical models of the basic drawbeads like circular drawbead, stepped drawbead, and squared drawbaed are first derived using the bending theory, belt-pulley equation, and Coulomb friction law. Next, the experiments for finding the drawing characteristics of the drawbead are performed. Based on mathematical models and drawing test results, expert models of basic drawbeads are then developed employing a linear multiple regression method. For the expert models of combined drawbeads such as the double circular drawbead, double stepped drawbead, circular-and-stepped drawbead, etc., those of the basic drawbeads are summed. Finally, in order to verify the expert models developed, the drawing characteristics calculated by the expert models of the double circular drawbead and circular-and-stepped drawbead are compared with those obtained from the experiments. The predictions by expert models agree well with the measurements by experiments.

• Transactions of Materials Processing
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• v.9 no.6
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• pp.638-643
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• 2000

This study Is concerned with the development of design support program for deep drawing process. The present support program is designed to generate the layout drawings by utilizing the following key functions: analysis of product shape, generation of key stages by pattern database, determination of layout generation method, generation of layout. furthermore, from the results by process design program input data for simulation Is automatically generated with appropriate process parameters and connected seamlessly to carry out the finite element analysis so that the design can be checked for the possible problems in real manufacturing process. The designer can generate layout drawings and test the design by simulation quickly and conveniently In these system designer can verify and optimize the design. We tested this system for various type of product shape md found that the generated layout is in good agreement with the real cases.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.28-31
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• 2001

Friction for sheet metal forming affects improvement of deep drawing formability. The deep drawing is affected by many process variables, such as lubricant, blank shapes, shape radius and so on. Especially, lubrication is very important formability factor. In this study, in order to investigate fraction coefficient of sheet metal forming, we examined friction test about three conditions, such as non-lubrication, full lubrication and film lubrication. We measured friction coefficient according to pin load under the conditions like deep drawing die. Mean friction coefficient for film lubrication condition would be very useful value to improve drawability.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.556-559
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• 2008

In this study, the failure in circular cup deep drawing simulation at warm temperature is predicted using forming limit diagram (FLD). The FLD is used in sheet metal forming analysis to determine the criterion for fracture prediction. The simulation with heat transfer of circular cup deep drawing at warm temperature was conducted. To predict the failure, the simulation with heat transfer used FLD at temperature in the vicinity of maximum thinning. The result of the simulation with heat transfer shows that the drawn depth increases with increasing temperature and is in accord with the experimental results above $150^{\circ}C$. The FLD provides a good guide for the failure prediction of warm forming simulation with heat transfer.

• Transactions of Materials Processing
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• v.21 no.1
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• pp.49-57
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• 2012

It is difficult to estimate the properties of multilayered sheet because they are composed of one or more different materials. Plastic deformation behavior of the multilayered sheet is quite different as compared to each material individually. The deformation behavior of multilayered sheet should be investigated in order to prevent forming defects and to predict the properties of the formed part. In this study, the mechanical properties and formability of stainless steel-aluminum-magnesium multilayered sheet were investigated. The multilayered sheet needs to be deformed at an elevated temperature because of its poor formability at room temperature. Uniaxial tensile tests were performed at various temperatures and strain rates. Fracture patterns changed mainly at a temperature of $200^{\circ}C$. Uniform and total elongation of multilayered sheet increased to values greater than those of each material when deformed at $250^{\circ}C$. The limiting drawing ratio (LDR) was obtained using a circular cup deep drawing test to measure the formability of the multilayered sheet. A maximum value for the LDR of about 2 was achieved at $250^{\circ}C$, which is the appropriate forming temperature for the Mg alloy. Fracture patterns on a circular cup and thickness of formed part were predicted by a rigid-viscoplastic FEM analysis. Two kinds of modeling techniques were used to simulate deep drawing process of multilayered sheet. A single-layer FE-model, which combines the three different layers into a macroscopic single layer, predicted well the thickness distribution of the drawn cup. In contrast, the location and the time of fracture were estimated better with a multi-layer FE model, which used different material properties for each of the three layers.

• Physical Therapy Rehabilitation Science
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• v.11 no.2
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• pp.136-144
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• 2022

Objective: This study was to identify the effect of pressure biofeedback applied in various postures that allow the application of abdominal drawing-in. Design: A cross sectional study. Methods: The study intended to compare changes in the thickness of abdominal muscles between different postures when abdominal drawing-in was performed using a pressure biofeedback unit in five postures and to compare differences in terms of measures such as the transverse abdominis's preferential activation ratio(PAR). Data measured from 30 healthy individuals were used for data analysis. A paired t-test and repeated measures analysis of variance was performed to compare the thickness of each abdominal muscle. Results: The transverse abdominis's and internal oblique's thickness showed statistically significant differences in all postures when abdominal drawing-in (p<0.05). In the comparison between the postures, statistically significant differences were observed between the positions of hook-lying and wall support standing and between supine and wall support standing and between hook-lying and sitting (p<0.05). In terms of the transverse abdominis's PAR in each posture, statistically significant differences were observed between hook-lying and quadruped, hook-lying and sitting, hook-lying and wall support standing, quadruped and supine, sitting and supine, as well as wall support standing and supine (p<0.05). Conclusions: When abdominal drawing-in using pressure biofeedback unit is performed for stabilization exercises, selecting and applying specific postures according to targeted muscles and the subject's functional ability will help provide a more efficient and accurate intervention.