• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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• pp.169-172
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• 2002

Recently, the application of 3-roll mill is increasing, because of its flexibility in spread control and stand arrangements due to its compact size. But deformation characteristics and microstructural change in the process is not well known. In this study, austenite grain size (AGS) predictions were made by isothermal FE analyses and a microstructure model available in the literature. From this study, the effect of draught on the AGS characteristics was analyzed based on the divided zones of two major recrystallization behaviors.

• Structural Engineering and Mechanics
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• 제10권4호
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• pp.371-392
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• 2000

Application of "advanced analysis" methods suitable for non-linear analysis and design of steel frame structures permits direct and accurate determination of ultimate system strengths, without resort to simplified elastic methods of analysis and semi-empirical specification equations. However, the application of advanced analysis methods has previously been restricted to steel frames comprising only compact sections that are not influenced by the effects of local buckling. A concentrated plasticity method suitable for practical advanced analysis of steel frame structures comprising non-compact sections is presented in this paper. The pseudo plastic zone method implicitly accounts for the effects of gradual cross-sectional yielding, longitudinal spread of plasticity, initial geometric imperfections, residual stresses, and local buckling. The accuracy and precision of the method for the analysis of steel frames comprising non-compact sections is established by comparison with a comprehensive range of analytical benchmark frame solutions. The pseudo plastic zone method is shown to be more accurate and precise than the conventional individual member design methods based on elastic analysis and specification equations.

• 소성∙가공
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• 제20권8호
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• pp.534-539
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• 2011

The production technology is the basic of manufacturing for various materials and components. This technology can influence the quality and productivity of leading export products such as automobile, ship, and electronic device. Besides, the production technology is very useful to apply to other manufacturing fields and has a great ripple effect. However, it is very difficult to make the production technology into standardization and knowledge-based database because the production technology is dependent in hands-on experience. In this study, the knowledge-sharing platform for the molding & forming technology which is a branch of the production technology is introduced. This platform is web-based system and has the knowledge authoring tool technologies storage, semantic database, and web portal service. Therefore, the molding & forming technology can be shared and spread easily by the knowledge-sharing platform.

• 소성∙가공
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• 제28권2호
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• pp.89-97
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• 2019

In this paper, we examine the application of a new concept - on-line FE model in various metal rolling processes. This technology allows for completion of process simulation within a tiny fraction of a second without losing the high level of prediction accuracy inherent to FEM. The procedure is systematically demonstrated through the design of actual on-line models for the prediction of the width spread in horizontal rolling of the slab using a dog bone profile and horizontal rolling of the strip with a strip profile. The validity and the prediction accuracy of the on-line FE models were analyzed and discussed.

• 소성∙가공
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• 제11권2호
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• pp.108-113
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• 2002

The application fields of medicine and biology are spotlighted because of the increasing concentration of health and the abundance of life. MEMS is very good solution in this fields for the concept of point of care which makes systems more useful and spread wide. This paper shows the major fabrication schemes and application fields of microelectromechanical system specially in medicine and biology fields.

• 한국강구조학회 논문집
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• 제18권6호
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• pp.687-696
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• 2006

본 논문에서는 공간 뼈대구조의 탄-소성 후좌굴 강도를 파악하기 위한 효율적인 수치해석 기법을 개발하고, 매개변수해석을 통하여 보-기둥 및 뼈대구조물의 비탄성 후좌굴 거동을 분석하였다. 외력의 증가에 따라 점진적인 강도감소효과를 효율적으로 고려하는 개선된 소성힌지 해석법을 적용하여 문헌에서 제시된 다양한 잔류응력 분포 형태에 따른 뼈대구조물의 탄-소성 해석을 수행하였다. 요소의 소성화 진행정도를 나타내는 파라미터들을 도입하고 등가단면력 및 요소분할에 따른 매개변수해석을 수행하여 그 결과를 문헌에서 제시된 소성영역해석, 쉘요소를 이용한 정밀해석 그리고 실험결과와 비교하여 뼈대구조물 극한강도를 평가하였다.

• 소성∙가공
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• 제20권3호
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• pp.243-249
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• 2011

In this study, an approach designed to compute high temperature friction coefficients for SCM 435 steel through a pilot hot rolling test and a finite element analysis, is proposed. Single pass pilot hot flat rolling tests with reduction ratios varying from 20 to 40% were carried out at temperatures ranging from 900 to $1200^{\circ}C$. In the proposed approach, the friction coefficient is calculated by comparing the measured strip spread and the roll force with the simulation results. This study showed that the temperature and reduction ratio had a significant influence on the friction coefficient. As both material temperature and reduction ratio become higher, the friction coefficient increases monotonically. This finding is not in agreement with the Ekelund model, which is widely used in the analysis of the hot rolling process. In the present work, the friction coefficient at a reduction ratio of 40% was found to be 1.2 times greater than that at a reduction of 30%. This higher friction coefficient means that an increment of the roll thrust force is expected at the next stand. Therefore, a roll pass designer must understand this phenomenon in order to adjust the reduction ratio at the stands while keeping the driving power, the roll housing structure and the work roll strength within the allowable range.

• 소성∙가공
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• 제18권5호
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• pp.410-415
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• 2009

Experimental and numerical studies were performed to examine the effect of material temperature and reduction ratio on friction coefficient during hot flat rolling. We carried out a single pass pilot hot flat rolling test at the temperatures range of $900{\sim}1200^{\circ}C$ and measured the spread of deformed material while reduction ratio varied from 20% to 40%. Materials used in this study were a high carbon steel and two alloy steels. The dimension of specimen used in hot rolling experiment was $50mm{\times}50mm{\times}300mm$. We performed a series of finite element simulation of the hot rolling process to compute the friction coefficient change in terms of steel grade and reduction ratio. Results showed that temperature dependency of friction coefficient is not noteworthy but the effect of reduction ratio on friction coefficient is quite large. For high carbon steel, friction coefficient at reduction ratio of 30% is lower than that at that of 20%. Meanwhile friction coefficient at reduction ratio of 40% was one and half times large compared with that at that of 20%. The effect of steel grade on friction coefficient was significant when reduction ration was large, e.g., 40%.

• 소성∙가공
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• 제22권1호
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• pp.42-47
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• 2013

The bicycle is one of the most important eco-friendly transport methods which can mitigate global warming. The portability of a bike on public transportation systems is essential for the wide spread use of bicycles by people in urban environments. In this study, a lightweight urban folding bike was developed with careful consideration of the association with public transport. A folding frame using a moving slide link mechanism made from AL6061 is proposed. Numerical analysis was conducted to evaluate structural safety of the bike in both vertical and pedal loading tests. The proposed urban folding bicycle weights only 10kg and summation of its width, length, and height in the folded configuration is under 158cm.

• 소성∙가공
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• 제19권3호
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• pp.185-190
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• 2010

Application of CAE analyses are wide spread in shaping processes and structural safety verification of plastic products. The importance of CAE analysis and its contributions are getting increase since the processibility and structural safety of product can be predicted. CAE analysis for complex shaped product need a lot of time for modeling and computation compare with simpler one. Therefore careful simulation modeling is required for complex shaped product. Structural analysis for plastic door handle of automobile has been performed and structural safety has been investigated for various load directions and modeling cases. Large stress occurred at the hinge in handle regardless of load direction and modeling case. Consequently hinge is considered structurally very weak among the parts in plastic door handle. It is concluded that simple modeling rather than total modeling with adequate boundary condition equivalent to real situation gives reasonable computational results with saving modeling effort and computation time.