• Transactions of Materials Processing
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• v.21 no.1
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• pp.58-66
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• 2012

The work roll surface temperature rises and falls repetitively during hot slab rolling because the work roll surface is cooled continuously by water. This study focused on Std. No. 7 to determine a cooling method which significantly reduces the tangential tensile stresses on the work roll surface of the hot slab mill at Hyundai Steel Co. in Korea. A series of finite element analyses were performed to compute the temperature distribution and the tensile stresses in the circumferential direction of the work roll. The virtual slab model was used to reduce the run time considerably by assigning a high temperature to the virtual slab. Except for the heat generated by plastic deformation, this is equivalent to the hot rolling condition that a high temperature slab (material) would experience when in contact with the work rolls. Results showed that when the virtual slab model was coupled with FE analysis, the run time was found to be reduced from 2000 hours to 70 hours. When the work roll surface cooled with a certain on-off patter of water spray, the magnitude of the tangential stresses on the work rolls were decreased by 54.1%, in comparison with those cooled by continuous water spraying. Savings of up to 83.3% in water usage are possible if the proposed water cooling method is adopted.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.1
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• pp.88-99
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• 1996

The explicit scheme for finite element analysis of sheet metal forming problems has been widely used for providing practical solutions since it improves the convergency problem, memory size and computational time especially for the case of complicated geometry and large element number. The explicit schemes in general use are based on the elastic-plastic modeling of material requiring large computataion time. In the present work, a basic formulation for rigid-plastic explicit finite element analysis of plain strain sheet metal forming problems has been proposed. The effect of some basic parameters involved in the dynamic analysis has been studied in detail. Thus, the effective ranges of parameters have been proposed for numerical simultion by the rigid-plastic explicit finite element method. A direct trial-and-error method is introduced to treat contact and friction. In computation, sheet material is assumed to possess normal anisotropy and rigid-plastic workhardening characteristics. In order to show the validity and effectiveness of the proposed explicit scheme, computations are carried out for cylindrical punch stretching and the computational results are compared with those by the implicit scheme as well as with a commercial code. The proposed rigid-plastic exlicit finite element method can be used as a robust and efficient computational method for analysis of sheet metal forming.

• Archives of Plastic Surgery
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• v.37 no.1
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• pp.12-21
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• 2010

Purpose: This work aimed to elucidate the anti-inflammatory effect of pegmatite in vitro and in vivo. Methods: Author evaluated the suppressive effects of pegmatite on lipopolysaccharide (LPS)-stimulated nitric oxide (NO) production, TNF-${\alpha}$ and IL-6 release in the RAW 264.7 murinemacrophages. Results: Treatment of RAW 264.7 cells with pegmatite significantly reduced LPS-stimulated NO production and inflammatory cytokine such as TNF-${\alpha}$ and IL-6 secretion in a concentration-dependent manner. Also pegmatite showed topical anti-inflammatory activity in the arachidonic acid (AA)-induced ear edema and acetic acid-induced increase in capillary permeability assessment in mice. It was also found that pegmatite (10 mg per ear in DW) inhibited arachidonic acid induced edema at 24 h more profoundly than 1 h by topical application. Furthermore, the vascular permeability increase induced by acetic acid was significantly reduced in mice that received pegmatite in 50 mg per mouse. Conclusion: Therefore the results of the present study suggest that pegmatite is a potent inhibitor of the LPS-induced NO and inflammatory cytokine in RAW 264.7 macrophages and showed anti-inflammatory activities in vivo animal model.

• Archives of Plastic Surgery
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• v.36 no.1
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• pp.89-92
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• 2009

Purpose: The clinical syndrome of unilateral finger ischemia, caused by digital artery occlusions from embolization from the palmar ulnar artery associated with repetitive striking of the palm, has been called the hypothenar hammer syndrome (HHS). We report the case of a man with this unique disease probably caused by manual work. Methods: A 52 - year - old male left - hand dominant manual worker complained of pain and coldness in the left 4,5th finger. On physical examination, there was a tip necrosis and the result of Allen's test was mildly positive(sluggish filling of hand from the ulnar artery). Arteriograms confirmed occlusion of the distal ulnar artery without direct perfusion of the superficial palmar arch and distal digital artery. Surgical bypass with reverse autologous vein grafting was performed between ulnar artery and superficial palmar arch, common digital artery. Results: He had an uneventful postoperative course and has remained asymptomatic for 18 months since discharge. Patency has been confirmed by color doppler with resolution of cold intolerance and successful digital preservation. Conclusion: We introduce very unique pattern of vascular ischemic disease and recommend the arterial bypass with vein interpositional grafting.

• Archives of Plastic Surgery
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• v.48 no.3
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• pp.310-322
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• 2021

The incidence of extremity amputation is estimated at about 200,000 cases annually. Over 25% of patients suffer from terminal neuroma or phantom limb pain (TNPLP), resulting in pain, inability to wear a prosthetic device, and lost work. Once TNPLP develops, there is no definitive cure. Therefore, there has been an emerging focus on TNPLP prevention. We examined the current literature on TNPLP prevention in patients undergoing extremity amputation. A literature review was performed using Ovid Medline, Cochrane Collaboration Library, and Google Scholar to identify all original studies that addressed surgical prophylaxis against TNPLP. The search was conducted using both Medical Subject Headings and free-text using the terms "phantom limb pain," "amputation neuroma," and "surgical prevention of amputation neuroma." Fifteen studies met the inclusion criteria, including six prospective trials, two comprehensive literature reviews, four retrospective chart reviews, and three case series/technique reviews. Five techniques were identified, and each was incorporated into a targetbased classification system. A small but growing body of literature exists regarding the surgical prevention of TNPLP. Targeted muscle reinnervation (TMR), a form of physiologic target reassignment, has the greatest momentum in the academic surgical community, with multiple recent prospective studies demonstrating superior prevention of TNPLP. Neurorrhaphy and transposition with implantation are supported by less robust evidence, but merit future study as alternatives to TMR.

• Archives of Plastic Surgery
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• v.49 no.4
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• pp.538-542
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• 2022

Performing the first peer review of a plastic surgical research article can be an overwhelming task. However, it is an essential scholarly skill and peer review is used in a multitude of settings: evaluation of journal articles, conference abstracts, and research proposals. Furthermore, peer reviewing provides more than just the opportunity to read and help improve other's work: peer reviewing can improve your own scientific writing. A structured approach is possible and recommended. In these ten tips, we provide guidance on how to successfully conduct the first peer reviews. The ten tips on peer reviewing concern: 1) Appropriateness: are you qualified and prepared to perform the peer review? 2) Familiarization with the journal and its reviewing guidelines; 3) Gathering first impressions of the paper followed by specific tips for reviewing; 4) the abstract and introduction; 5) Materials, methods, and results (including statistical considerations); and 6) discussion, conclusion, and references. Tip 7 concerns writing and structuring the review; Tips 7 and 8 describe how to provide constructive criticism and understanding the limits of your expertise. Finally, Tip 10 details why-and how-you become a peer reviewer. Peer review can be done by any plastic surgeon, not just those interested in an academic career. These ten tips provide useful insights for both the aspiring and the experienced peer reviewer. In conclusion, a systematic approach to peer reviewing is possible and recommended, and can help you getting started to provide quality peer reviews that contribute to moving the field of plastic surgery forward.

• Archives of Plastic Surgery
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• v.50 no.4
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• pp.335-339
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• 2023

It is undeniable that a significant number of patients who want to improve their facial appearance is increasingly interested in nonsurgical procedures. Without a doubt, the use of autologous fat could not be left out as a magnificent alternative for nasal modeling simply because of four influential factors: ease of collection, compatibility, the temporality of the results, and safety. This work describes an innovative alternative technique for nasal modeling using micrografts enriched with adipose-derived mesenchymal stem cells (ASCs). With this technique, fat was collected and divided into two samples, nanofat and microfat. Nanofat was used to isolate the ASCs; microfat was enriched with ASCs and used for nasal modeling. Lipoinjection was performed in a supraperiosteal plane on the nasal dorsum. Through a retrolabial access, the nasal tip and base of the columella were lipoinjected. We consider that nonsurgical nasal modeling using micrografts enriched with ASCs can be an attractive and innovative alternative. This technique will never be a substitute for surgical rhinoplasty. It can be performed in a minor procedure area with rapid recovery and return to the patient's daily activities the next day. If necessary, the procedure can be repeated.

• International journal of advanced smart convergence
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• v.4 no.1
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• pp.127-136
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• 2015

This paper is a study of a simple distillation process. Its objective is to compare fuel production from plastic waste, its data collecting is from the factory and simple data calculated a suitable evaluation on the simple distillation plant built before calculation. The experiment with a simple distillation process is separated into three sections. The first section is a simple distillation process of distillation producing diesel using heat source by biomass. The second section is distillation process which produces fuel using heat source by burner. The third section uses heat source by burner incorporate with biomass. The experiment reveals that the result of the second section is the most efficient. In comparison with the experiments and the simple calculation, the result on the efficiency of work has error less than 5% and it is sufficient for the next experimental process. Thus, the study and design on a simple distillation process produces fuel from plastic waste has to concern mainly on design heat exchangers, flow rate and optimized temperature. Further study on this plant can be developed throughout the county due to its low cost and efficiency.

• Transactions of Materials Processing
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• v.18 no.2
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• pp.177-182
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• 2009

A work of thin-walled outsell injection molding technology for a plastic part of moldframe applicable in a display product was performed in the present study. The thin-walled plastic part is one of the core parts in the display product, which supports and protects a light guide plate and back light unit from external environmental conditions. It globally has the shape of rectangular and surrounds the light guide plate and back light unit for each class of inch, however, the cross section of the part is not clear to define the thickness. This causes the difficult problem of injection molding itself for the part. Moreover, a metal outsell part makes a difficult problem in injection molding over it. Because the mold temperature control of the parts are not uniform in thickness direction due to the metal part. A careful injection melding analysis and injection mold design from the analysis results have to be proceeded to obtain a production of precision moldframe. Therefore, optimization for injection molding process and analysis of warpage characteristics were studied. Consequently, it was possible from the presented virtual manufacturing process that the manufacturing of precision thin-walled outsell moldframe.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.5
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• pp.16-25
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• 1996

In the present work a rigid-plastic finite element formulation using dynamic explicit time integration scheme is proposed for numerical analysis of auto-body panel stamping processes. The rigid-plastic finite element method based on membrane elements has long been employed as a useful numerical technique for the analysis of sheet metal forming because of its time effectiveness. A damping scheme is proposed in order to achieve a stable solution procedure in dynamic sheet forming problems. In order to improve the drawbacks of the conventional membrane elements, BEAM(abbreviated from Bending Energy Augmented Membrane) elements are employed. Rotational damping and spring about the drilling direction are introduced to prevent a zero energy mode. The lumping scheme is employed for the diagonal mass matrix and linearizing dynamic formulation. A contact scheme is developed by combining the skew boundary condition and the direct trial-and-error method. Computations are carried out for analysis of complicated auto-body panel stamping processes such as forming of an oilpan, a fuel tank and a front fender. The numerical results of explicit analysis are compared with the implicit results with good agreements and it is shown that the explicit scheme requires much shorter computational time, especially when the problem becomes more complicated. It is thus shown that the proposed dynamic explicit rigid-plastic finite element method enables an effective computation for complicated autobody panel stamping processes.