• 소성∙가공
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• 제9권3호
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• pp.249-256
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• 2000

Tube hydroforming is recently drawing attention of automotive industries due to its seberal advantages over conventional methods. It can produce wide range of products such as subframes, engine cradles, and exhaust manifolds with cheaper production cost by reducing overall number of processes. Tube hydroforming process is divided into prebending process and hydroforming process. Tube bending ins an important factor of the hydroforming process to enable the tube to be placed in the die cavity. This paper presents the theoretical analysis and the simulation results of the tube bending process. With some assumptions, approximate equations are derived to predict the thickness distribution on the cross section and the spring back of the bent tube. Bending simulations are carried out and compared to the analytical and experimental results.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.172-175
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• 2003

Run-Out-Table is the region between EDT and CT. Hot killed strip is cooled by air and water in ROT. In this procedure, phase transformation and shape deformation occur due to temperature drop. Because of un-ideal cooling condition, deformation of strip and non-uniform phase distribution come into existence. This phenomenon affects the strip property and lead th the existence of residual stress. And it exerts effects on the Coiling process, Coil Cooling process, and Un-coiling process. Through these process, the residual stresses of strip are more larger and unbalance of these stresses become more severe. Finite element (FE) based models for the analysises of non-steady state heat transfer and elastoplastic deformation are described in this investigation. The analysises of thermodynamics and phase transformation kinetics are suggested also. Using the ROT simulation result coiling process and coil cooling process simulations are carried out.

• 한국정밀공학회지
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• 제16권1호통권94호
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• pp.182-190
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• 1999

The objective of this study is to develop an analysis scheme in order to predict regrinding due to tool wear in shearing process. The analysis of material now and fracture in shearing process should precede the prediction of tool wear. Thus the developed FE-program to analyze shearing process is used. In order to predict tool wear, the wear model is reformulated as an incremental form and then the wear depth of tool is calculated at each deformation path. Because the regrinding of shearing tool is determined on the basis of allowable size of burr, the analysis of shearing process is iteratively performed using the worn profile of tool. To show the effectiveness of the scheme the simulation result is compared with experimental one.

• 한국경영과학회지
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• 제24권4호
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• pp.81-94
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• 1999

Organization change projects such as Business Process Redesign(BPR) have been implemented by many firms for enhancing their organizational performance. However, management is reluctant to initiate these projects due to enterprise-wide impact and steeper project cost than the traditional system development projects. Thus, there emerges a need to accurately assess the value of the redesigned organizational process for the successful implementation of BPR projects. The purpose of this study is to assess the value of process redesign in the point of resource utilization and allocation, and cycle time and cost reduction. The candidate process and the design alternatives are identified from organizational requirements analysis. The variables and their relations are defined to perform task activity analysis, bottleneck analysis, cycle cost analysis, and resource utilization analysis. A Case study of a manufacturing company indicates that the assessments method proposed in this study is a promising approach to identify the business alternative process that lead to the highest organizational performance.

• 한국실내디자인학회:학술대회논문집
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• 한국실내디자인학회 2006년도 추계학술발표대회 논문집
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• pp.54-57
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• 2006

The digital modeling process is visualization of designer's specific intension in digital virtual space by constructing computer and information system that fits the designer's intension and morphological characteristic of the space that to be modeled. Digital Modeling Process has been brought to attention for it's design efficiency and potentialities as new creative tool. The effect of DMP, in spacial design process has been grown from simply providing a ways to visualize designer's idea toward utilizing modeling data for real construction which includes architectural and constructional material. The purpose of this study is to find optimal methodological answers to spatial design process that is improved and specialized due to rapid improvement of digital media.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.759-762
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• 2000

Rapid Prototyping (RP) techniques have their unique characteristics according to the working principles: stair-stepped surface of parts due to layer-by-layer stacking, low build speed caused by line-by-line solidification to build one layer, and additional post processing to improve surface roughness, so it is required very high cost to introduce and to maintain RP apparatus. The objective of this study is to develop and design a new RP process, Variable Lamination Manufacturing using expandable polystyrene foam sheet as part material (VLM-S), which can make up for the disadvantage of existing techniques, and to develop an apparatus to implement the process. In order to examine the possibility of practical utilization of the proposed VLM-S process for prototyping of a general three-dimensional shape, an auto-shift lever knob and a pyramid shape were fabricated.

• 한국기계가공학회지
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• 제14권1호
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• pp.44-50
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• 2015

This paper presents a heuristic process-optimization procedure for minimizing warpage in injection-molded parts based on the dynamic robust design methodology. The injection molding process is known to have intrinsic variations of its process conditions due to various factors, including incomplete process control facilities. The aim of the robust design methodology advocated by Taguchi is to determine the optimum design variables in a system which is robust to variations in uncontrollable factors. The proposed procedure can determine the optimal robust conditions of injection molding processes at a minimum cost through a trade-off strategy between the degree of warpage and the packing time.

• 한국기계가공학회지
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• 제19권5호
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• pp.75-81
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• 2020

Multistage hot forging process enables mass production of various parts at a high speed, wherein, it is important to design the forging steps in an optimal way. Finite element methods are widely applied for optimizing the forging process design; however, they present inaccurate results due to the rapid change in the mold temperature during multistage hot forging. In this study, the temperature distributions of the mold in a steady state were calculated via heat transfer analysis during mold cooling. The flow stress and friction coefficient of the material were measured according to the temperature and were applied for numerical analysis of the multistage hot forging process. Eventually, the accuracy of the analysis results is verified by comparing these results with the experiments.

• 한국정밀공학회지
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• 제10권2호
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• pp.66-75
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• 1993

This paper proposes a monitoring method for nondestructive and in-process measurement of the case depth in LASER surface heat treatment process. The method is essentially an eddy-current method, and measures sensing coil's electrical impedance which varies with the changes of the material microstructure due to hardening. To investigate te validity of the proposed method a series of experiments were performed for various hardning depths. The results show that the relationship between the eddy- current sensor output and the changes in case depth is almost linear. This indicates that the eddy-current measuring method can be used as one of the possible monitoring method for mesauring the hardened depth in LASER heat treatment processes.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.759-762
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• 2000

In order to reduce lead-time and cost, recently the technology of Rapid Prototyping and Manufacturing (PR/M) has been used widely. So various RP/M methods have been developed and these systems commercialized several years ago. But we have carried out rapid product, such as sphere, by the milling process instead of RP system. in the case of sphere with three-dimensional shape. the machining method using conventional milling machine has resulted in some troubles because of its deformation and lack of stiffness which is due to usual work piece set up method. In this paper, the feasibility of milling process which is divided into two steps such as the-upper-and-1ower-face milling process using supporting material were investigated and suggested.