• Transactions of Materials Processing
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• v.11 no.8
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• pp.691-700
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• 2002

Injection molded plastic parts have many surface detects: weld line, sink mark, flow mark, gloss, shading, scratching, and so on. Because these surface faults have not been accepted esthetically, plastic parts are Produced through painting or texturing. The purpose of this paper is to develop a paintless molded part of TV Mask Front by flow control method and gas-assisted injection molding. In order to minimize defects from injection molding, this study was carried out using computer aided injection mold filling simulations using MF/FLOW and MF/GAS. Based on these numerical results, we developed FR(Flame Retardant) HIPS and established guidelines of part design, mold design, and Processing conditions. We have achieved of cost sayings, improvement of productivity, and utilization of recycling by eliminating surface defects and painting process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.09a
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• pp.126-131
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• 2005

In the present study, warpage characteristics of mobile phone cover through injection molding process were investigated by using design of experiments. Warpage in plastic injection molding process has a significant effect on quality of product. Effects of injection time, packing pressure, packing time, mold temperature ana melt temperature on warpage of mobile phone cover were considered by CAE analysis and experiment with Taguchi method. The degree of warpage for the injection molded product was measured by using three dimensional CMM. It was shown that temperature parameter has more significant effect on the warpage of mobile phone cover than pressure parameter.

• Design & Manufacturing
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• v.8 no.1
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• pp.40-44
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• 2014

As a rotating machine element, plastic gears are more and more widely used in such as industrial machine element, since plastic gear is lighter, higher wear-resistance, and higher vibration absorbing ability than metal gears. When operating plastic parts, tooth breakage and fatigue life shortened due to increasing number of applying load and tooth flank temperature rising, such that accuracy of plastic gears is divided from allowable range to cause vibration and noise. On this study, a internal plastic gears are developed which improved the filling balance molding process by a new injection mold structure. The new mold structure called HR3P(hot runner type 3plate mold). As the result from this studies, we obtained a very accurate roundness internal gears by using design of experiment.

• Journal of Power System Engineering
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• v.12 no.6
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• pp.78-82
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• 2008

Plastic gears are more and more widely used in many industrial machine elements. Plastic gear has higher properties such as light weight, wear resistance, and vibration absorbing ability than metallic gears. But, in case of using an inaccurate plastic gear, its tooth breakage happen and fatigue life is shortened due to increase of applying load and temperature rising on the tooth flank. Inaccuracy of plastic gears such as pitch circle roundness and tooth profile generates vibration and noise. In this study, an internal plastic gears which is molded by a new injection mold structure are developed. The new mold structure is called the HR3P(hot runner type 3plate mold) that has an improved runner system in order to have good filling balance. As a result from this study, an internal gear with very accurate roundness was developed by using design of experiment.

• 한국금형공학회:학술대회논문집
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• 2008.06a
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• pp.129-133
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• 2008

As a rotating machine element, plastic gears are more and more widely used in such as industrial machine element, since plastic gear is lighter, higher wear-resistance, and higher vibration absorbing ability than metal gears. When operating plastic parts, tooth breakage and fatigue life shortened due to increasing number of applying load and tooth flank temperature rising, such that accuracy of plastic gears is divided from allowable range to cause vibration and noise. On this study, a internal plastic gears are developed which improved the filling balance molding process by a new injection mold structure. The new mold structure called HR3P(hot runner type 3plate mold). As the result from this studies, we obtained a very accurate roundness internal gears by using design of experiment.

• Archives of Plastic Surgery
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• v.48 no.1
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• pp.127-130
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• 2021

Rectovaginal fistula, which can arise after an injury to the vaginal canal or rectum, is a troublesome obstacle for patients' everyday life. In most cases, it can be covered with a local flap, but previous radiation therapy increases the recurrence rate, making it especially difficult to cure. As the application of stromal vascular fraction (SVF) obtained from enzymatically digested autologous adipose tissue has become increasingly common, several reports have advocated its effectiveness for the treatment of refractory wounds. In light of the angiogenic, regenerative characteristics of SVF, it was incorporated as a treatment option in two cases of rectovaginal fistula discussed here. As described in this report, irradiated rectovaginal fistulas in rectal cancer patients were successfully treated with SVF injection, and we suggest SVF as a feasible treatment option for cases of rectovaginal fistula that would otherwise be very difficult to cure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.317-318
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• 2007

• Design & Manufacturing
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• v.2 no.5
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• pp.11-15
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• 2008

A micro-injection mold for ultra-thin-walled plate was considered in this work. The proposed mold system is for the fabrication of ultra-thin walled plastic plate with micro features by injection molding. As the injection molding of thin-walled plastic, which has the thickness under $400{\mu}m$, itself is not easy, the injection molding of the micro-features in the thin-walled structure is more complicated and difficult. To investigate the basic phenomenon of the ultra-thin walled part during the injection molding process, design of the part and mold system were performed in the present study. The injection molding and structural analysis of the suggested part and mold system were also performed. Consequently, injection molding system for ultra-thin walled plate with micro features were manufactured and presented.

• Archives of Craniofacial Surgery
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• v.21 no.1
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• pp.15-21
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• 2020

Background: Autologous fat is considered an ideal filler material, and the use of cryopreserved fat grafts is promising in terms of flexibility and efficiency. Therefore, cryopreserved fat grafts have become more common in recent years; however, their complications require further consideration. Methods: We evaluated 53 patients who underwent facial lipofilling at our institution to confirm the clinical usefulness and safety of cryopreserved fat. Fresh fat injections with or without cryopreserved fat were administered. At one or more sites, 22 patients had a single fresh fat injection, four patients had two or more fresh fat injections, 16 patients had one fresh fat injection followed by one cryopreserved fat injection, six patients had one fresh fat injection followed by two cryopreserved fat injections, and five patients had two fresh fat injections and one or more cryopreserved fat injections. Results: In total, 281 sets of injection procedures were performed at various sites, of which 170 involved one fresh fat injection, 89 involved one fresh fat injection and one cryopreserved fat injection, and 11 involved one fresh fat injection and two cryopreserved fat injections. One patient experienced self-resolving inflammation as a complication after the second injection in the right cheek. No statistically significant differences were found between the fresh and cryopreserved fat injections. Conclusion: We suggest that cryopreserved fat is a useful and safe resource for multiple fat injections, with advantages including aseptic fat handling and the delicacy of the technique.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.2
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• pp.27-34
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• 2004

In the injection molding of plastic optical lenses, the molding conditions have critical effects on the quality of the molded lenses. Since there are many molding parameters involved in injection molding process, determination of the molding conditions for lens molding is very important in order to precisely control the surface contours of an optical lens. Therefore this paper presents the application of neural network in suggesting the optimized molding conditions for improving the quality of molded parts based on data of FE Analysis carried out through CAE software, Timon-3D. Suggested model in this paper, which serves to learn from the data of FE Analysis and induce the values for optimized molding conditions. has been implemented for searching the molding conditions without void and with minimized thickness shrinkage at lens center of injection molding optical lens. As the result of this study. we have confirmed that void creation at the inside of lens is primarily determined by mold temperature and thickness shrinkage at center of lens is primarily determined by the parameters such as holding pressure and mold temperature.