• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.427-428
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• 2009

In the manufacture process of refrigerator cabinet, polyurethane(PU) liquid firstly is injected between outer plate and inner case in high temperature about $40^{\circ}C$, and PU foam is generated and solidified to the room temperature. There will be great residual stress in the PU foam, especially at the corners after the whole refrigerator is completely assembled. The stress condition will become more complicated under operating condition because of the large temperature difference between the freezing room and outer plate. And also, there are great differences of properties for plastic and steel which would cause different deformation under temperature gradient. The steel outer plate would expand compared to the PU foam or ABS material under operation condition, which induces a thermally bowing deformation in the refrigerator cabinet. The objective of this paper is to design an optimum bead structure or to use reinforcement in the refrigerator except for improving material properties in order to decrease the deformation.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.2
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• pp.60-65
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• 2021

In this study, the effect of pressure type and foaming agent on the microstructural change of Al foam produced by powder compact processing was investigated. Better foaming characteristic is easily obtained from extrusion process with strong plastic deformation and preheating than that by uniaxial pressing with preheating. In current powder compact foaming process using TiH2/MgH2 mixture as a foaming agent, a temperature of 670℃ and addition of 30% MgH2 in TiH2 foaming agent was chosen as the most suitable foaming condition. The aluminum (Al) foams with maximum porosity of around 70%, relatively regular pore size and distribution were successfully produced by means of the powder metallurgy method and extrusion process.

• Korean Journal of Metals and Materials
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• v.48 no.2
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• pp.109-115
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• 2010

In the present study, a Zr-based amorphous alloy matrix composite reinforced with tungsten porous foam was fabricated without pores or defects by liquid pressing process, and its microstructures and mechanical properties were investigated. About 69 vol.% of tungsten foam was homogeneously distributed inside the amorphous matrix, although the matrix of the composite contained a small amount of crystalline phases. The compressive test results indicate that the composite was not fractured at one time after reaching the maximum compressive strength, but showed considerable plastic strain as the compressive load was sustained by tungsten foam. The tungsten foam greatly improved the strength (2764 MPa) and ductility (39.4%) of the composite by homogeneously dispersing the stress applied to the matrix. This was because the tungsten foam and matrix were simultaneously deformed without showing anisotropic deformation due to the excellent bonding of tungsten/matrix interfaces. These findings suggest that the liquid pressing process is useful for the development of amorphous matrix composites with improved strength and ductility.

• Journal of the Korean Burn Society
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• v.22 no.1
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• pp.15-19
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• 2019

Purpose: Pain management in burn treatment is important in improving wound healing and quality of life. Ibuprofen is a proven pain relieving agent in patients with partial thickness burn by intraveous injection. The purpose of this study is to evaluate the efficacy of Biatain Ibu^® (polyurethane foam containing ibuprofen) in pain control for outpatients with partial thickness burns. Methods: A prospective randomized clinical trial was performed in outpatients with partial thickness burn from August 1, 2017 to July 31, 2018. Acute pain, chronic pain, complications, days for re-epithelialization and patient's satisfaction were compared between Biatain Ibu^® and Biatain^® groups. Results: A total of 20 patients (Biatain Ibu^®, n=10; Biatain^®, n=10) were assessed in the trial. On Burn days 3, 5, 7, 11, 13, and 15, the acute pain levels were significantly lower in the Biatain Ibu^® group than in the Biatain^® group. Complications, chronic pain levels and days for re-epithelialization were not significantly different between the two groups. Patient's satisfaction was not statistically significant but was higher in the Biatain Ibu^® group. Conclusion: Biatain Ibu^® is effective in relieving pain in outpatients with partial thickness burn without decreasing patient satisfaction, wound healing ability or developing any complications.

• Composites Research
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• v.31 no.4
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• pp.122-127
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• 2018

Sandwich composites of carbon fiber reinforced plastic(CFRP) and polymer foam will be used to automobile and aerospace industry according to increasing importance of light weight. In this study, mechanical and heat resistance properties of sandwich composites were compared with type of polymer foam (polyethylene terephthalate(PET), polyvinylchloride(PVC), epoxy and polyurethane). All types of polymer foams were degraded to 30, 60, 120, 180 minutes in $180^{\circ}C$. After heat degradation, the polymer foams were observed using optical microscope and compressive test was performed using universal testing machine(UTM). Epoxy foam had the highest compressive property to 2.6 MPa and after thermal degradation, the mechanical property and structure of foam were less changed than others. Epoxy foam had better mechanical properties than other polymer foams under high temperature. Because the epoxy foam was post cured under high temperature. As the results, Epoxy foam was optimal materials to apply to structures that thermal energy was loaded constantly.

• Composites Research
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• v.37 no.2
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• pp.86-93
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• 2024

The inner foam structure plays an important role in the performance of the carbon-fiber-reinforced plastic (CFRP) rear spoiler used in automobiles. However, there is still a lack of studies for the CFRP-based rear spoiler according to the type of inner foam, especially under the high-speed driving condition. With this motivation, we numerically analyze the performance of the CFRP rear spoiler using various cases of the inner foam under the highspeed driving condition. Here, polymethacrylimide (PMI), polyvinyl chloride (PVC), and styrene acrylonitrile (SAN) resins are employed as the inner foams in this work. The performances are evaluated using the deformation aspects and vibration characteristics when the driving condition is a high-speed condition (200 km/h). Furthermore, to specifically verify the importance of the inner foam in the high-speed condition, we additionally investigate the performance of the CFRP rear spoiler without the inner foam structure (i.e., hollow type). As a result, it is confirmed that among the types of inner foams utilized in this work, the PMI and PVC inner foams have the best deformation aspect and vibration characteristic, respectively. Note that the hollow-type inner foam has inferior performances compared to other inner foams invoked in this study. Consequently, through this study, it can be confirmed that the inner foam structure can significantly improve the performance of the CFRP spoiler under high-speed driving condition (200 km/h), and also that the strengths of the CFRP spoiler can manifest differently depending on the types of inner foam core.

• Archives of Plastic Surgery
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• v.36 no.5
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• pp.548-554
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• 2009

Purpose: To evaluate clinical efficacy and safety of hyaluronic acid based autologous dermal fibroblasts (Hyalograft 3D) in the treatment of diabetic foot ulcers. Methods: A total of 28 patients with diabetic ulcers were randomized to either the control group with nonadherent foam dressings(n=14) or the treatment group with autologous tissue - engineered grafts(n=14). Weekly assessment contained vital sign checks, ulcer size measurements, and wound photos. At 12th week, percentages of complete wound healing and mean healing times were compared. Safety was also monitored by adverse events. Results: Complete wound healing was achieved in 84.6% of the treatment group and 23.1% of the control group (p<0.005). The mean times of closures for the treatment versus control groups were 6.1 weeks and 10.9 weeks, respectively. No adverse events related to the study treatment occurred. Conclusion: The use of hyaluronic acid based autologous fibroblast grafts was found to be a safe and effective treatment for diabetic foot ulcers.

• Journal of the Korean Institute of Gas
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• v.7 no.1 s.18
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• pp.28-32
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• 2003

In order to apply the properties of fiber reinforced plastic(FRP) to support panel of polyurethane foam in LNG storage tank, we estimated the mechanical properties, degree of vapour barrier, chemical stability and thermal conductivity changes as ageing. According to the results, the mechanical strength (i.g. compressive strength, bending strength, tensile strength and shear strength) are more than 30 times higher than those of plywood. The FRP-polyurethane foam(PUF) composites have lower thermal conductivity changes as ageing than plywood-PUF composites. FRP-PUF sandwich composite for LNG storage tank with these remarkable properties are compared the abilities of these structures with those of the conventional structures(plywood-PUF sandwich composite). Finally, we can obtain the effects such as superior mechanical properties and fuel saving through improved ability of vapor barrier.

• Archives of Plastic Surgery
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• v.40 no.4
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• pp.380-386
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• 2013

Background Xanthelasma palpebrarum (XP) is a benign disorder manifesting as yellowish cholesterol-laden plaques on the eyelids. This paper presents the outcomes in patients with XP who have undergone surgical excision as the main modality of treatment. Methods A retrospective review of patients who received surgery for xanthelasma palpebrarum from March 2007 to March 2011 was conducted. Patients were classified into four grades according to the location and extent of the lesion, with grade I being the mildest and grade IV being the most diffuse. Simple excision was performed in grade I and II lesions, while local flaps and skin grafts were performed in the more advanced grades. Results Ninety-five cases from March 2007 to March 2011 were included in this study. 66 cases (70%), were treated by simple excision. Twenty-four cases (25%) and 5 cases (5%) were treated by simple excision in combination with or without local flaps and skin grafts. In approximately 1/4 of the patients, orbicularis oris muscle involvement was observed. 4 patients (4.2%) developed scar contracture postoperatively, which required a secondary procedure. Recurrence was reported in 3 patients (3.1%). Otherwise. There were no other reports of major complications or disfigurement. Conclusions We found that for lesions involving the deep dermis and/or muscle, surgical excision was the most appropriate therapeutic option.

• Transactions of Materials Processing
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• v.11 no.4
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• pp.323-331
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• 2002

The combination of rapid prototyping(RP) and rapid tooling(RT) has a potential for rapid manufacturing of three-dimensional parts. In the present study, a new RP system transfer type Variable Lamination Manufacturing using Expandable Polystyrene Foam (VLM-ST), is proposed to fabricate net shapes of three-dimensional prototypes. Various three-dimensional parts, such as a knob shape and a human head shape, are manufactured by the VLM-ST apparatus. In addition, a new rapid tooling technology, which utilizes a room temperature vulcanizing (RTV) molding technique and a triple reverse process technique, is proposed to manufacture net shapes of three-dimensional plastic parts using the prototypes of VLM-ST. A plastic part of the knob shape is produced by the proposed RT technology. The combination of the proposed RP and RT enables the manufacture of a plastic knob within two days.