• 소성∙가공
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• 제15권7호
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• pp.524-528
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• 2006

Although equal channel angular pressing (ECAP), imposing large plastic shear strain deformation by moving a workpiece through two intersecting channels, is a promising severe plastic deformation method for grain refinement of metallic materials, its batch type characteristic makes ECAP inefficient for multiple-passing. Rotary-die ECAP (RDECAP) proposed by Nishida et al. can achieve high productivity by using continuous processing without taking out the samples from the channel. However, plastic deformation behavior during RD-ECAP has not been investigated. In this study, material plastic flow and strain hardening behavior of the workpiece during RD-ECAP was investigated using the finite element method. It was found that plastic deformation becomes inhomogeneous with the number of passes due to an end effect, which was not found seriously in ECAP. Especially, decreasing corner gap with increasing the number of passes was observed and explained by the strain hardening effect.

• Archives of Plastic Surgery
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• 제32권5호
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• pp.582-588
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• 2005

Digital imaging is emerging as a standard method for patient documentation in clinical setting. Managing patient expectations before aesthetic surgery can greatly improve patient satisfaction after surgery. The patient who visited for plastic surgery wants a predicted figure after the operation. A virtual plastic surgery software is necessary in order to satisfy the desire of patients. Adobe $Photoshop^{(R)}$ is the professional standard in desktop digital imaging, offers indispensable new features for graphic and web design, photography, and video. Using imaging technology, it takes just minutes to realistically simulate the results of double eyelid operation, liposuction, rhinoplasty or any other aesthetic procedure. The aim of this study is to analyze the significance of the digital image processing and to introduce the virtual plastic surgery using Adobe $Photoshop^{(R)}$.

• 소성∙가공
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• 제12권8호
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• pp.738-743
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• 2003

The major problems of a plastic injection mould can be devided into two kinds, one is in mould another in injected parts. Most of defects of the former comes from mould design, such as, structure and working. The latter are weld line, warpage, sink mark, burning, flow mark, scratching, shading, black hole and so on. Most of problems in injection molding are difficult to find the reason because of complexity. The purpose of this paper is to improve the quality of plastic injection mould and parts with inquiring the counter plan and analizing troubles of the part of Flat TV Front Cover by flow control method and gas-assisted injection moulding. For minimizing defects of the injection moulded parts, computer aided simulation method for injection mould filling was used. Based on these numerical results, the guidelines of mould design and injection processing condition were established. As a result, the improvement of quality, such as minimizing surface defects of injection moulding parts and troubles in mould was achieved.

• 소성∙가공
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• 제12권2호
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• pp.83-87
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• 2003

Current state of plastic processes of steel bearing parts is surveyed. According to the advances in plastic forming technologies and their great advantage to mass production, plastic processes are adopted in manufacturing majority of bering parts. The rings are forged or ring rolled and the rolling elements, i.e, balls or rollers are cold formed before fine machining. Bearing's steel retainers are mainly press formed using cold rolled seel strips. Including the general explanation about above processes, some details of forging technology, control of forging temperature and after cooling process, and examples of computer simulation are described.

• Archives of Plastic Surgery
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• 제42권1호
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• pp.28-33
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• 2015

Background Topical anesthetics, such as eutectic mixture of local anesthetics (EMLA) cream, can be applied to reduce pain before minor procedure. This trial evaluated EMLA as pretreatment for facial lacerations and compared pain, discomfort and overall satisfaction. Methods This trial included consecutive emergency department patients ${\geq}16years$ of age who presented with simple facial lacerations. At triage, lacerations were allotted to either the routine processing group or EMLA pretreatment group according to date of admission. Initially, the emergency department doctors inspected each laceration, which were dressed with saline-soaked gauze. In the pretreatment group, EMLA cream was applied during wound inspection. The plastic surgeon then completed primary closure following the local injection of an anesthetic. After the procedure, all patients were given a questionnaire assessing pain using the 10-point visual analog scale (VAS) ("no pain" to "worst pain"). All questionnaires were collected by the emergency department nurse before discharge. Results Fifty patients were included in the routine processing group, and fifty patients were included in the EMLA pretreatment group. Median age was 39.9 years, 66% were male, and the average laceration was 2.67 cm in length. The EMLA pretreatment group reported lower pain scores in comparison with the routine processing group (2.4 vs. 4.5 on VAS, P<0.05), and lower discomfort scores during the procedure (2.0 vs. 3.3, P=0.60). Overall satisfaction was significantly higher in the EMLA pretreatment group (7.8 vs. 6.1, P<0.05). Conclusions Pretreating facial lacerations with EMLA topical cream aids patients by reducing pain and further enhancing overall satisfaction during laceration treatment.

• 자원리싸이클링
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• 제18권1호
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• pp.13-21
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• 2009

본 연구에서는 마찰하전형정전선별법을 적용하여 EVA(ethylene vinyl acetate)와 PET(polyethylene terephthalate) 혼합 폐플라스틱의 재활용을 위한 재질분리 연구를 수행하였다. 하전물질 선정을 위한 하전특성 연구결과, PP(polypropylene)재질이 EV4와 PET 폐플라스틱의 재질분리에 가장 효과적인 하전물질로 확인되어, PP재질의 pipe-type 하전장치를 개발하였다. 본 연구에서 개발된 하전장치를 이용한 재질분리 실험결과, 최적 실험조건에서 PET의 품위와 회수율이 각각 98.7%와 89.7%인 결과를 얻었다.

• 통합자연과학논문집
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• 제13권4호
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• pp.158-169
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• 2020

Modern people live in the age of plastics. It has been widely used due to its easy molding processing, mass production, and excellent durability. However, over-produced plastics for convenience cause plastic disasters and adversely affect the ecosystem. Since the COVID-19 outbreak, the use of single-use plastic waste due to the use of delivery services has increased. The COVID-19 pandemic has caused a plastic pandemic. Currently, domestic recycling policies depend only on recycling collection companies and market prices of recyclable resources. This paper confirms whether the outbreak of COVID-19 has affected the price of plastic waste. It also shows that the price of plastic waste is more unstable than metals with a high recycling rate. This urges businesses to share the cost of recycling on plastic waste, no longer being dependent on market prices for recyclable resources.

• Journal of the Korean Wood Science and Technology
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• 제42권5호
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• pp.499-509
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• 2014

Wood filler is a porous and anisotropic material having different size, shape, and aspect ratio. The use of wood fillers such as wood particle, wood flour, and wood pulp in wood plastic composites (WPCs) are growing rapidly because these wood fillers give improved strength and stiffness to WPCs. However, the wood fillers have originally poor compatibility with plastic matrix affecting the mechanical properties of WPCs. Therefore, to improve compatibility between wood and plastic, numbers of physical and chemical treatments were investigated. While the various treatments led to improved performances in WPC industries using petroleum-based plastics, full biodegradation is still issues due to increased environmental concerns. Hence, bio-based plastics such as polylactide and polyhydroxybutyrate having biodegradable characteristics are being applied to WPCs, but relatively expensive prices of existing bio-based plastics prevent further uses. As conventional processing methods, extrusion, injection, and compression moldings have been used in WPC industries, but to apply WPCs to engineered or structural places, new processing methods should be developed. As one system, co-extrusion technique was introduced to WPCs and the co-extruded WPCs having core-shell structures make the extended applications of WPCs possible.

• 한국산학기술학회논문지
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• 제4권1호
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• pp.42-46
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• 2003

섬유 코팅제로 널리 쓰이고 있는 액상 PVC는 여러 가지 특성 중 무광택 효과가 뛰어나지만 코팅된 섬유 표면의 유연성이 감소된다. 이런 결함을 대체할 수 코팅 물질로 Elastomer계열의 액상 실리콘 고무를 사용했다. 기존 액상 PVC공정과 동일하게 진행했으며, 로울러의 압축력과 공정상의 예비경화를 이용했다. 실험 결과 액상 PVC로 코팅된 직물의 경도는 70E, 인장강도는 10.3 MPa, 신율은 200%로 측정되었다. 액상 실리콘 고무로 코팅된 직물의 경도는 40도, 인장강도는 5.1 MPa, 신율은 460%,였다. 따라서 액상 실리콘 고무 코팅은 3차 가공 없이 액상 PVC 코팅보다 플라스틱 직물 표면의 무광택성과 유연성을 증가시켰다.

• 소성∙가공
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• 제32권3호
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• pp.129-135
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• 2023

The use of engineering plastic products in internal combustion engine and electric cars to improve stiffness and reduce weight is increasing significantly. Among various lightweight materials, engineering plastics have significant advantages such as cost reduction, improved productivity, and weight reduction. In particular, engineering plastics containing glass fibers are used to enhance stiffness. However, the stiffness of glass fibers can increase or decrease depending on their orientation. Before developing plastic products, optimal designs are determined through injection molding and structural analysis to enhance product reliability. However, reliable analysis of products with variable stiffnesses caused by anisotropy cannot be achieved via the conventional isotropic structural analysis, which does not consider anisotropy. Therefore, based on the previously reported study "the Effect of Impacted Fracture in Glass Fiber Orientation with Injection Molding & Structural Coupled Analysis," this study aims to investigate the structural analysis and degradation mechanisms of various polymers. In particular, this study elucidates the actual mechanism of plastic fracture by analyzing various fracture conditions and their corresponding simulations. Furthermore, the objective of this study is to apply the injection molding and structural coupled analysis mechanism to develop engineering plastic products containing glass fibers. In addition, the study aims to apply and improve the plastic fracture mechanism in actual products by exploring anisotropy and stiffness reduction owing to the unfilled polymer weld line.