• Archives of Plastic Surgery
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• v.33 no.6
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• pp.700-705
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• 2006

Purpose: For hypertrophic scars and keloids no universally effective treatment modality exists. Surgical revision, intralesional steroid injection, silicone gel sheeting, pressure, laser, and others have been used with variable success, but many treatments are associated with high recurrence rates. Although optimal treatment remains undefined, successful treatment can be obtained through a combined therapeutic approach. Methods: We used three therapeutic modalities in combination, which are intralesional injection of triamcinolone acetonide, silicone gel sheeting, and 585 nm flashlamp-pumped pulsed dye laser. Fifty-eight cases of hypertrophic or keloid scar were treated by combined therapeutic regimen for mean period of 18 months. The changes of thickness, color, and pliability of scars were evaluated with clinical photographs by grading scale. Results: As summing the grades and categorizing the result into three group, we obtained 28% good, 67% fair, and 5% poor results. There was a desirable improvement of scars with insignificant adverse effects. Conclusion: Combination of intralesional steroid injection, silicone gel sheeting, and pulsed dye laser can lead to successful treatment of hypertrophic scar and keloid.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.10
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• pp.1549-1554
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• 2010

Recently, plastic screws have replaced metal screws because of the former's light weight, thermal and electrical insulating properties, and anticorrosion characteristics. Plastic screws are usually produced by injection molding, which involves material shrinkage during the solidification of the polymer. This shrinkage results in the degeneration of the dimensional accuracy. In the present study, the effect of injection-molding conditions on the dimensional accuracy of plastic screws was investigated through a numerical simulation of injection molding; on the basis of this simulation, we could determine the mold-design parameters. The design of experiment was applied in accordance with the numerical analysis in order to optimize the injection-molding conditions with a view to improving the dimensional accuracy of the precision plastic screw.

• Archives of Plastic Surgery
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• v.33 no.1
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• pp.120-123
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• 2006

Spontaneous extensor pollicis longus tendon rupture is commonly caused by attrition of the tendon from trauma or inflammatory processes. We experienced a patient with extensor pollicis longus tendon rupture after steroid injection, in which the rupture may have been caused by the effects of steroid itself as well as direct damage from the needle. A 51-year-old woman complained of inability to extend her right thumb at the first metacarpophalangal & interphalangeal joint level. The patient had a history of local steroid injection into the dorsal & radial side of wrist on two occations, and had no history of trauma or rheumatologic disease. After a physical examination of the patient, we decided to explore the wrist. The patient agreed with operation. Intraoperatively, an incision was made into the wrist and the proximal and distal ends of the ruptured extensor pollicis longus tendon were identified. The defect between the proximal and the distal end was measured to approach 8cm, and a palmaris longus tendon graft was performed. After three months of rehabilitation, the first metacarpophalangal & interphalangeal joint recovered the normal range of motion. Steroid injection has been widely used in various musculoskeletal disorders such as rheumatoid arthritis and osteoarthritis. However, inadvertent steroid injection into the extra or intra articular spaces may lead to tendon rupture. Steroids reduce tensile strength by decreasing tenocyte activity and collagen synthesis. Also, the physical effect of direct needle-stick injury into the mesotenon and blood vessels around the tendon may cause damage. In addition, hematoma and edema may increase pressure around the tendon and compromise blood supply, leading to tendon degeneration and subsequent rupture. When injecting steroid into an articular area, all physicians should have a complete understanding of the surrounding anatomy and always keep in mind the hazards of such procedures.

• Archives of Plastic Surgery
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• v.35 no.1
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• pp.56-61
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• 2008

Purpose: There was no controlled study on botox injection and neurectomy for treatments of muscle hypertrophy. Although many studies have shown the clinical effects of each treatment, it was not able to evaluate and compare the effects of each treatment because there was no comparison of the two treatments under the same experimental condition. Hence, the aim of this study is to com Methods: The study was carried out on 21 rabbits. 9 rabbits received botox injection(botox injection group), and neurectomy was performed to another 9 rabbits (neurectomy group). 3 rabbits did not receive any treatment(control group). To compare and analyze the effects of muscular atrophy, muscle was stained with NADH-TR, and the changes in size of the muscle fiber were examined. And the electromyography was examined. In each group, muscle fiber was stained and electromyography was performed 2, 3, and 6 months after injection or operation. Results: In histological test and electromyography, in the neurectomy group, the size of muscular fiber and amplitude of electromyography decreased until 2 months after neurectomy. And decreased results were maintained with the passage of time. It showed irreversible aspect. On the other hand, in the botox injection group, the decrease in the size of muscular fiber and amplitude of electromyography was observed until 2 months after injection. In 3 months after the injection, it was slowly getting back to original size and had almost recovered by 6 months after the injection. It showed reversible aspect. Conclusion: This study shows researches about clinical effect of botox injection and neurectomy coincide with the results of experiment under the same experimental condition.

• Journal of the Korean institute of surface engineering
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• v.35 no.3
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• pp.113-120
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• 2002

Injection molded plastic parts have many surface defects. These include a weld line, sink mark, flow mark, gloss, shading, scratching etc. Because these surface faults are not aesthetically acceptable, plastic parts are produced through painting or texturing. The purpose of this paper is to develop paintless molded parts using a flow control method. Computer aided injection mold filling simulations were used in order to minimize the number of defects from injection molding. Based on the numerical results, FR(Flame Retardant) HIPS was developed and the guidelines for part design, mold design, and the processing conditions were established. The effects of cost savings, improvements in productivity, and recycling were considered by reducing the number of surface faults and eliminating the painting process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.308-311
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• 2004

Nowadays, plastic industry has needed to produce parts that require high precision and quality. To make a high precision and quality part, before injection molding, plastic material is investigated about their properties such as shrinkage, warpage, etc. In this study, experiments were conducted with PA6(polyamid) to figure out shrinkage behavior according to three type aspect ratio of samples. The injection speed that affects on shear rate, molecular orientation within plastic part was determined as main variable of experiment. As a result of experimental study, part shrinkage had a tendency to be decreased by increasing injection speed and aspect ratio of samples.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.784-787
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• 2003

The present work covers three-dimensional flow simulation and deformation analysis of injection molded plastic lenses using solid elements. A numerical scheme to evaluate part deformation has been proposed from the results of injection molding analysis. Proposed scheme has been applied to the injection molding processes of optical plastic lenses: a spherical lens and an aspheric lens for a photo pick-up device. Through the simulation processes. residual stress is estimated and the final deformed patters are obtained for both products. The reliability of the proposed approach has also been verified in comparison with the results of real experiments.

• Archives of Craniofacial Surgery
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• v.19 no.3
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• pp.218-221
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• 2018

Patients complaining of swelling and hematoma caused by contusion of the face can be easily seen in the emergency room. Most of the treatments were conservative treatments such as ice bag application, mild compression dressing, and massage. During the follow-up, fibrosis progression due to hematoma was frequently observed in the contusion site. When hematoma or fibrosis is confirmed, hyaluronidase (H-lase) 1,500 IU and 2 mL of normal saline were mixed and subcutaneously injected in crisscross manner. To evaluate the improvement of hematoma before and after hyaluronidase injection, three plastic surgeons evaluated using the Vancouver scar scale and compared preoperative and postoperative images. Hematoma and fibrosis after facial trauma improved after hyaluronidase injection for early treatment.

• Journal of the Korea Society of Computer and Information
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• v.23 no.11
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• pp.123-128
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• 2018

When the injection molding system molds some plastic products, defective product rate will be increased if plastic materials have some excessive moisture content. Therefore, it is very important to control the dehumidification and drying of plastic material. Since the moisture content of the plastic material may change from time to time depending on the material and the molding process, it is necessary to observe the change in real time and maintain a constant moisture content. To solve these problems, I proposed a smart factory system model for plastic molding in this paper. In addition, I designed the interface module to be installed in the dehumidifying dryer which is the core of this process. In addition to this, performance tests were conducted to check the effectiveness and the results were verified as valid.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.2
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• pp.93-98
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• 2015

This study focuses on simulation technology in the injection molding process for plastic optic lenses. The CAE program 3D TIMON was used to predict retardation, flow patterns and warpage deformation. The results were compared to the results of optic lenses as measured using the WPA-100 retardation measurement device with injection molding CAE for retardation predictions. According to the analysis and measured results, the distributions of retardation between the CAE results and the measurement results were similar. It was also confirmed that varying the injection speed had an effect on the injection pressure, warpage deformation and retardation distribution. As the injection speed increases, the injection pressure also increases and warpage deformation decreases. However, as the injection speed increases, the retardation distribution deteriorates.