• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.12
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• pp.2936-2948
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• 1993

Multi-stage deep drawing is an important sheet metal forming process. The deformation mechanisms of sheet metals during forming processes are complicated mainly due to the geometry and the lubrication of tools involved, the formability and the anisotropic behaviour of the material. The multi-stage deep-drawing processes including normal-drawing, reverse-drawing, and re-drawing are analyzed by use of the rigid-plastic finite element method. The anisotropic behaviour represented by r-value can be incorporated into the formulation. Punch/die loads and thickness distributions were obtained as results of simulating axisymmetric deep drawing processes. The computed results showed good agreements with experiments.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2004.11a
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• pp.173-174
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• 2004

The Great Wall is an element in University which stand outs as a landmark. The Great Wall is located in front of the grand staircases of the gymnasium in the main gate area. Falling water and Lights shows a spectacle panorama in various point of view. Water falls down the top of the grand staircases and the front walls. And the red, blue and green lights brighten the falling water in the evenings. Also the relief of the palm tree and turtle symbolizes the University Identity. The wall is comprehends not only the day and the night but four seasons. The Water, Lights, and the Relief are coordinates well along with the new building in campus.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.9
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• pp.1451-1456
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• 2003

In code roll forming processes, the sheet metal strip is gradually and successively bent into a desired profile. Occurrence of buckling is one of the major defects. Buckling may occur due to longitudinal stress and it is difficult to predict buckling behavior. In this study an analytical method for buckling behavior during roll forming is proposed. All numerical simulations are performed by finite element analysis. The behavior of buckling can be predicted with the simulation modeling of the finite element method.

• Journal of the KSME
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• v.30 no.3
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• pp.237-245
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• 1990

3차원 강소성 유한요소법과 독특한 updating 방법으로 실험결과와 잘 일치하는 실용적인 프로그 램을 개발할 수 있었다. 몇 가지 해석결과의 예에서 알 수 있듯이 소재의 변형을 정확하게 예 측할 수 있고, 임의의 단면현상을 가진 로울에 대하여도 해석이 용이하였다. 링 로울링의 제작 공정을 3차원 강소성유한요소법으로 해석할 수 있고, 실험적으로 해석결과의 타당성을 결정지 음에 따라서, 링 로울링에 대한 연구결과는 보편적인 기대 이상으로 첨단산업분야에 기여할 수 있을 것으로 보여진다. 현재 링 로울링에 대한 국내에서의 관심은 비교적 적은 편이나, 항공우 주산업 분야중 부품제작분야 및 제반 기계공업분야 특히 소성성형가공 분야에서, 해석적 방법의 지속적인 개발 및 실험적 연구와 뒷받침은 궁극적으로 이 분야의 공정 및 소재 설계의 자동화 내지는 전산화로 이끌 것이며, 장차 이 분야를 국제적으로 주도해 나가고자 하는 데 필수적인 것으로 여겨진다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.9 s.252
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• pp.1049-1061
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• 2006

In the study, the flow stress of material and friction condition were determined by using the cylinder compression test and numerical method. We proposed the flow stress equation including the initial yield strength to predict it from the upper bound method. The upper bound technique uses the velocity field which includes two unknowns to effectively express bulging. Also, inverse engineering technique uses the object function to minimize area enclosed by load-stroke curve. The friction factor is determined from the radius of curvature of the barrel by cylinder compression test. Flow stress and initial yield strength predicted from the above techniques are verified through the finite element simulation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.7
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• pp.1107-1118
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• 2001

The forming limit diagram introduced by Keeler and Goodwin has been used generally to analyze the formability of sheet metal. However, path dependent forming limit curves based on the state of strain can be explained only by a single criterion which is based on the state. In this study, experimental forming limits in strain space of some metal sheets are transformed into forming limit curves in stress space. Effects of yield criterion are investigated in transforming the forming limit curves. Some important design aspects which are based on the close prediction of movements in forming limit curves during sheet forming are concluded.

• Journal of Korean Physical Therapy Science
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• v.1 no.2
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• pp.215-222
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• 1994

The aim of this study was to determine the normative strength value for cervical flexors, extensors and right lateral flexors, left lateral flexors to provide a guideline for rehabilitation of cervical radiculopathy patients. The isometric evaluation of cervical flexors, extensors and lateral flexors by using the Hand-held dynamometer was performed on 50 males and 50 females. The result were as follows. The average cervical muscle strength were 5.7 kg in flexor. 10.5 kg in extensors, and 6.6 kg in right lateral flexor, 6.5 kg in left lateral flexor. There was statistically significant difference between the cervical flexors and extensors(p<0.01) but no significant difference between right lateral flexor and left lateral flexor. There was statistically significant difference between male and female(p<0.01). When one of cervical muscle was strong, also the others did in subjects(p<0.01) and the body weight was significantly releated to the cervical muscle strength(p<0.01).

• Transactions of Materials Processing
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• v.5 no.2
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• pp.130-137
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• 1996

The sheet formability can be improved by the optimum drawbeads installation because draw-beads can control the flow of the metal into the die cavity when the punch enters into the die opening, In this study the drawing characteristics for step drawbead are analyzed by 2-D rigid -plastic FEM and also are measured experimentally. In addition for the validity of FEM theoretical results are compared with the experimental results. Especially the draw bead restrain-ing forces and the strain distributions of drawn specimens are obtained in both FEM and experiment. Also the effects of the drawbead dimensions drawing angles and blank holding forces on the drawing characteristics are investigated.

• Transactions of Materials Processing
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• v.3 no.3
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• pp.347-358
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• 1994

The purpose of the study is to form $\Omega$-type bellows without any defect by specific rollers which are designed based on the volume distribution technique. In the present paper, we proposed a forming process of existing U-type bellows to a value-added $\Omega$-type in a progressive manner. It was developed to shape a perfect $\Omega$-type bellows after preforming from initial U-type bellows to final U-type bellows. To examine the suggested 'processing condition design' some experiments were performed in a real scale. It was found out that the spring back effect played a major role in deviating the geometry of formed bellows from the predicted one. The problems found in the experiment can be used as important information in manufacturing equipment for forming $\Omega$-type bellows.

• Journal of Korea Foundry Society
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• v.41 no.6
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• pp.521-527
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• 2021

This study presents a process management method for the detection of casting defects during in high-pressure die casting based on machine learning. The model predicts the defects of the next cycle by extracting the features appearing over the previous cycles. For design of the gearbox, the proposed model detects shrinkage defects with data from three cycles in advance with 98.9% accuracy and 96.8% recall rates.