• 소성∙가공
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• 제17권6호
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• pp.407-411
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• 2008

A brake system in automobile is one of the important parts that directly affect the safety of passengers. Particularly, disk brake module is applied to almost all kinds of automobile brake system due to its remarkable braking power and braking distance. In the disk brake module of an automobile, the bolt for tire wheel is assembled to the disk brake hub by interference fit(bolt pressing process). The process induces small deformation whose range is within tens of ${\mu}m$ and this deformation may cause the runout badness of the whole disk brake module, and even braking problems such as judder or squeal phenomena which makes the loss of braking efficiency. In this study, bolt pressing fit into hub was simulated by $ANSYS^{TM}$, a commercial structure analysis program. Also, the aspect and the cause of hub displacement were analyzed and the solution for decreasing runout of hub was proposed.

• Journal of Welding and Joining
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• 제18권2호
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• pp.227-227
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• 2000

Pressure vessels usually consist of main body and pipes which are connected with the main body. And as joining method of such main body and pipes, welding is carried out. After welding, welding residual stresses inevitably occur around welded joints. As residual stresses act harmfully on fatigue strength, corrosion and buckling strength of structure, PWHT is carried out for the purpose of removing the residual stress. But, during PWHT process, 2 ¼Cr-1Mo steels are frequently apt to generate reheat crack. For this reason, it is strongly needed to analyze and examine the mechanical behavior of welded joints before and after PWHT process. So, in this study, welded nozzle parts of pressure vessel where reheat cracks frequently occur are selected for examining the mechanism of crack-occurrence. (Received December 2, 1999)

• Journal of Welding and Joining
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• 제18권2호
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• pp.100-104
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• 2000

Pressure vessels usually consist of main body and pipes which are connected with the main body. And as joining method of such main body and pipes, welding is carried out. After welding, welding residual stresses inevitably occur around welded joints. As residual stresses act harmfully on fatigue strength, corrosion and buckling strength of structure, PWHT is carried out for the purpose of removing the residual stress. But, during PWHT process, $2\frac{1}{4}Cr-1Mo$ steels are frequently apt to generate reheat crack. For this reason, it is strongly needed to analyze and examine the mechanical behavior of welded joints before and after PWHT process. So, in this study, welded nozzle parts of pressure vessel where reheat cracks frequently occur are selected for examining the mechanism of crack-occurrence.

• Journal of Mechanical Science and Technology
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• 제20권6호
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• pp.806-818
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• 2006

The shear spinning process, where the plastic deformation zone is localized in a very small portion of the workpiece, shows a promise for increasingly broader application to the production of axially symmetric parts. In this paper, the three components of working force are calculated by the newly proposed deformation model in which the spinning process is understood as shearing deformation after uniaxial yielding by bending, and shear stress, $\tau_{rz}$ becomes $\kappa$, yield limit in pure shear, in the deformation zone. The tangential forces are first calculated and the feed forces and the normal forces are obtained by the assumption of uniform distribution of roller pressure on the contact surface. The optimum contact area is obtained by minimizing the bending energy required to get the assumed deformation of the blank. The calculated forces are compared with experimental results. A comparison shows that theoretical prediction is reasonably in good agreement with experimental results.

• Journal of Advanced Marine Engineering and Technology
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• 제28권1호
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• pp.83-89
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• 2004

Flare nut is an important Part that used to joint a brake tube-end in automobiles. It was made of SWCH 10A by machining. But we studied to make it by metal forming. The main focus of this paper is to investigate an optimal forging processes for flare nut using the DEFORM$^{TM}$-3D. commercially available finite element code and tests. Actually an explicit finite element analysis of the flare nut forging processes has been carried out to predict an optimal shape of the flare nut and its results were reflected in the tests of the forging processes design for flare nut. The simulation results which had obtained from finite element analysis were contributed to the forging processes design for flare nut. An optimal shape of nave nut showed agreements with test results. Furthermore. this paper should contribute to a development of the forging process for a variety of parts.s.

• 소성∙가공
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• 제5권2호
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• pp.105-114
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• 1996

Recently, precision forging techniques are applied to manufacture spur gears. Compared to conventional machining, they produce parts of better mechanical properties and less residual stresses with a much higher production rate. In the present investigation a rigid-plastic three dimensional finite element method was applied to analyze hot forging and cold sizing of a spur gear by closed dies. The involute curve of a tooth profile was approximated by a circle close to the curve. Results of the analyses make it possible to predict local strengths of the gear die failure and an appropriate preform for cold sizing. It was found that the preform for cold sizing. It was found that the preform for the cold sizing is the most important because it determines whether the gears especially teeth can be successfully formed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.702-705
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• 2005

Burr is an undesirable projection as result of plastic deformation. Burr minimization and effective deburring process are required strongly to reduce the cost of the parts. In doing these efforts, the precise burr measurement must be provided for the efficient process. For this purpose the conoscopic holography sensors are selected before. However, it has been very difficult to measure micro burrs less than $10{\mu}m$ due to their tiny and sharp geometries as well as the effect of ambient vibration during scanning. A new micro burr measurement system using high precision. Conoprobe sensor and XY table can measure the micro burrs which is less than $10{\mu}m$. Experiments were carried out showing that micro burr around $10{\mu}m$ was successfully measured and analyzed.

• 한국정밀공학회지
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• 제16권11호
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• pp.224-233
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• 1999

The quality of injection molded parts is affected by the variables such as materials, design variables of part and mold, molding machine, and processing conditions. It is difficult to consider all the variables at the same time to predict the quality. In this paper neural network was applied to analyze the relationship between processing conditions and volumetric shrinkage of part. Engineering plastic gear was used for the study, and the learning data was extracted by the simulation software like Moldflow. Results of neural network was good agreement with simulation results. Nonlinear regression model was formulated using the test data of 3,125 obtained from neural network, Optimal processing conditions were calculated to minimize the volumetric shrinkage of molded part by the application of RQP(Recursive Quadratic Programming) algorithm.

• Archives of Plastic Surgery
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• 제38권6호
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• pp.851-860
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• 2011

Purpose: Reduction by simply assembling bones is recognized as treatment for a zygoma fracture. However, in patients who originally had a protruding zygoma, the fractured parts look like malarplasty after the edema subsides, giving a soft impression which patients notice. Thus, we created symmetry through simultaneous contralateral malar reduction in a unilateral zygoma fracture. Methods: In this study, the patients who had surgery between July, 2008 and December, 2009 with admission were object. In 76 patients with a zygoma fracture, the patients with bilateral zygoma fractures were excluded. Among 48 patients who had a reduction only after a unilateral zygoma fracture, the patients hoping for a reduction of their rough protruding zygoma were analyzed with front cephalometry. The study progressed on 22 patients who had simultaneous contralateral malar reduction in a unilateral zygoma fracture with consent. After fixing the fracture, we did a straight zygoma osteotomy through a 1.5 cm intraoral incision. After that, we created symmetry with a special ruler and fixed the broken zygomatic arch with a screw and plate. We evaluated the facial index and satisfaction with a statistical analysis before and after the surgery. Results: In 22 patients, there was no reoperation except for 1 patient who had a zygoma fracture. None of the patients were treated for infection or hematoma. Two patients complained of paresthesia after the malar reduction operation, but this subsided in 4 months. Most of them were satisfied with the malar reduction, especially the women, and we obtained a better mid facial contour with decreased facial width ($p$ <0.05). Conclusion: Existing zygoma fracture surgery focuses on anatomical reduction. However, we need to have a cosmetic viewpoint in fractures as interests of face contour arise. Thus, contralateral malar reduction got a 4.7 (range 0~5) from patients who had malar reduction surgery in our hospital. Although adjusting to all zygoma fractures has limitations, it can be a new method in zygoma fractures when there are limited indications of protruding zygoma and careful attention is given to patients' high demands.

• Composites Research
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• 제29권6호
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• pp.342-346
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• 2016

경량화 소재 중 CFRP(Carbon Fiber Reinforced Plastic)는 카본 섬유를 이용한 섬유구조물이다. 카본과 플라스틱의 특성을 갖는 복합소재이다. 섬유구조는 섬유방향으로 큰 강도를 갖는다. 이러한 경량 소재인 CFRP로 가장 많이 사용되는 것은 직조된 CFRP이다. 직조된 CFRP는 단방향 CFRP에 비하여 구조가 안정적이기 때문이다. 단직조된 CFRP는 고가이다. 따라서 본 연구는 단방향 CFRP의 섬유 구조 특성을 파악하고자 하였다. 본 연구에서는 적층각도 [0/X/-X/0]로 X를 변수로 갖는다. X의 각도 위상이 반전되어 적층된 단방향 CFRP이다. 이러한 단방향 CFRP를 이용하여 중앙 크랙을 갖는 두께 2 mm 판재 형태의 해석 모델을 이용하였다. 해석에서는 핀으로 연결된 상부와 하부에서 하중이 가해지고 있으며 중앙 크랙부분에서 파단을 연구한다. 해석 모델은 CATIA를 이용한 3D Surface 모델로 설계하였다. CFRP 적층을 위해, ANSYS프로그램에서 ACP를 이용한 적층 방향을 결정하여 2개의 적층들을 갖는 해석 모델을 만들었다. 이후 구조해석을 진행하였다.