• Journal of the Korean Society for Precision Engineering
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• v.13 no.11
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• pp.106-113
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• 1996

Using stainless steel as the cold forged parts especially the outer parts of automobile is gradually increasing because it can bear up against the erosion and the wear. During cold forging of the stainless steel the working pressure acting on die surface are very high therefore the wear on die surface can be greatly increased. In cold forging processes, die failure must be considered before die design. One of the main reasons of die failure in industrial application of metal forming technologies is wear. The die wear affects the tolerances of forged parts, metal flow and costs of processes etc. The only way to to control these failures is to develop methods which allow prediction of the die wear and which are suited to be used in the desing stage in order to optimize the process. In this paper, the rigid-plastic finite element method was combined with the wear prediction routine and then the forward extrusion process using stainless steel was analysed simultaneously. To minimize the die wear the FPS algorithm was applied and the optimal conditions of die configuration are suggested.

• Journal of Power System Engineering
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• v.18 no.3
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• pp.51-58
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• 2014

Injection molding simulation provided optimized design results by analyzing quality problems while the product is in assembly or in the process of manufacturing with make automobile plastics. Frequent change of design, change of injection molding, repetition of test injection which was held in the old way can now be stopped. And quality upgrade is expected instead. This report deals with the effect which the position of injection molding automobile console gate and number has on product quality including pressure at end of fill, bulk temperature at end of fill, shear stress of end of fill, residual stress at post filling end, product weld lines and warpage results. Simpoe-Mold simulates the complete manufacturing process of plastic injected parts, from filling to warpage. Simpoe-Mold users, whether they are product designers, mold makers or part manufacturers, can identify early into the design stage potential manufacturing problems, study alternative solutions and directly assess the impact of such part modification, whatever the complexity and geometry of such parts, shell part as plain solid parts.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.334-337
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• 2005

The objective of this research works is to propose a rapid development methodology of small size deep drawing tools for electronic parts utilizing the technology combination of CAE and RP/RT. The technology is applied to the development of deep drawing tools with a drain shape. The final surface of tools is obtained from the evaluation of the formability using the CAE. In order to manufacture the physical prototype of tools fer try-out terming, several fabrication experiments are carried out for three types of rapid tool manufacturing technology. Through the fabrication experiments, the acceptable rapid manufacturing technologies of deep drawing tools with a small size have been proposed.

• Archives of Plastic Surgery
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• v.37 no.2
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• pp.129-136
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• 2010

Purpose: Anatomically, the foot is provided with insufficient blood supply and is relatively vulnerable to venous congestion compared to other parts of the body. Soft tissue defects are more difficult to manage and palliative treatments can cause hyperkeratosis or ulcer formation, which subsequently requires repeated surgeries. For weight bearing area such as the heel, not only is it important to provide wound coverage but also to restore the protective senses. In these cases, application of flaps for hind foot reconstruction is widely recognized as an effective treatment. In this study, we report the cases of soft tissue reconstruction for which various types of flaps were used to produce good results in both functional and cosmetic aspects. Methods: Data from 37 cases of hind foot operation utilizing flaps performed between from June 2000 to June 2008 were analyzed. Results: Burn related factors were the most common cause of defects, accounting for 19 cases. In addition, chronic ulceration was responsible for 8 cases and so forth. Types of flaps used for the operations, listed in descending order are radial forearm free flap (18), medial plantar island flap (6), rotation flap (5), sural island flap (3), anterolateral thigh free flap (2), lattisimus dorsi muscular flap (2), and contra lateral medial plantar free flap (1). 37 cases were successful, but 8 cases required skin graft due to partial necrosis in small areas. Conclusion : Hind foot reconstruction surgeries that utilize flaps are advantageous in protecting the internal structure, restoring functions, and achieving proper contour aesthetically. Generally, medial plantar skin is preferred because of the anatomical characteristics of the foot (e.g. fibrous septa, soft tissue for cushion). However alternative methods must be applied for defects larger than medial plantar skin and cases in which injuries exist in the flap donor / recipient site (scars in the vicinity of the wound, combined vascular injury). We used various types of flaps including radial forearm neurosensory free flap in order to reconstruct hind foot defects, and report good results in both functional and cosmetic aspects.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1994.03a
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• pp.218-222
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• 1994

The chassis of T.V, cassette, radio and telephone are made up thin-iron plates that makes a lot of female screws to assemble various parts. Then makes hole in the iron plate and forming female screws of burring face after the burring. Female screws forming in thin-iron plate is very difficult working then rolled forming process use of plastic deformation instead of cut forming. In this study goals are solve the trouble problem of industrial field and develop new model tap for prevent chips.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.293-298
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• 1999

To make use of various switches, relays, and control instruments, a connector (jack) is used to link the battery (power) and operating units. A connector must have precision as well as solidity to control the power in a car. To improve productivity, we researched and developed a connector molding by adapting vacuum system and we've made it possible to minimize the incomplete molding and weld-line. As a result, good quality can be warranted with less costs.

• Transactions of Materials Processing
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• v.5 no.2
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• pp.165-175
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• 1996

the process of strip twisting is practiced for the manufacture of some commercial parts such as elements for tube type line mixers. A thin metal strip with rectangular cross section is twisted thru an angle greater than 180。. Initial geometry is altered in to a complex one with dimen-sional changes. In practice several tryouts are necessary to obtain required dimensional accu-racies. A simple analysis model is proposed to predict the dimensional changes forming torque and axial force.

• Proceedings of the KAIS Fall Conference
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• 2003.06a
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• pp.356-358
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• 2003

본 연구에서는 일반사출과 MmSH방식 두 가지의 사출성형공정을 이용하여 나노 패턴 구조물을 제작하였다. 성형품에 나타난 나노패턴의 진사성은 MmSH방식을 이용한 PC 성형품에서 가장 우수했다. 일반사출공정에서 HIPS로 제작된 성형품은 나노패턴의 전사가 잘 형성되었고, PC의 경우 전사가 잘 이루어지지 않았다. 연구 결과 수지의 유동성이 좋고, 금형표면 온도가 높을수록 나노패턴의 전사성은 향상됨을 알 수 있었다.

• Archives of Plastic Surgery
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• v.36 no.3
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• pp.356-360
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• 2009

Purpose: Lipofibromatous Hamartoma(LFH) of nerve is a tumor - like lipomatous process principally involving the young persons. This is rare disease characterized by a soft slowly growing mass surrounding and infiltrating major nerves and their branches of the palm and digits. LFH of nerve usually affects the median nerve, with the most common sites of presentation being the distal forearm and hand in the wrist or palm. It may cause symptoms of compression neuropathy and is associated with macrodactyly. Recently, MRI plays a major role in confirming the diagnosis of LFH. Therefore, we present two cases of LFH in the hand with MRI features and surgical management. Methods: One is 6 - years - old female who presented with macrodactyly involving both the soft tissue and bony parts of the second, third and forth digits of her right hand. The other one is 16 - years - old man who presented involving the soft tissue of the second and third digits of his right hand, with pain and numbness, along with motor and sensory deficits in the median nerve distribution. To evaluation about LFH, we enforced preoperative MRI and physical examination. After confirming the diagnosis of LFH, we proposed decompression of all compromised peripheral nerve to help alleviate pain and paresthesia to reduce the likelihood of permanent motor and sensory sequelae. Results: A characteristic feature on MRI is the appearance of serpentiform nerve fascicle surrounded by fibro - fatty tissue within the expended nerve sheet. Distribution of fat between fascicles is asymmetric. Two cases were treated by limited debulking of the redundant tumor tissue and excision of epineurial fatty tissue. These cases were performed with relief of symptom. Conclusion: MRI not only confirms the diagnosis, it also provides a detailed assessment of nerve involvement preoperatively. Especially, on coronal images, the nerve has a spagetti - like appearance that is pathognomonic of LFH. Recommendations for early treatment include decompression of the carpal tunnel, debulking of the fibro - fatty sheath, microsurgical dissection of the neural elements and excision of involve nerve with or without grafting.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.672-678
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• 2020

Ogive parts of large-caliber ammunition in Korea are manufactured by the Press Nosing method, but this method has the disadvantage of requiring additional processes such as lubrication before and after the press process. This study proposes the possibility of applying the Swaging method to improve these shortcomings. A large-diameter shell body was manufactured in sub-scale and plastic working experiments using a swaging process were performed. We investigated whether plastic processing is possible up to 75 % of the diameter reduction rate that satisfies the final molding dimension, and whether the dimensions of the product produced by swaging molding are satisfactory as the hardness changes according to the diameter reduction rate and the increase in thickness. The test using the prototype confirmed that the hardness increased proportionally with the diameter reduction rate and by more than HV 335 at the reduction rate of 75 %. The material thickness variation tended to be similar to the theoretical calculated value, and the thickness increase rate was proportional to 65.4 % at the reduction rate of 75 %.