• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.4
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• pp.345-349
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• 2014

In this study, an age-hardened 6061-T6 alloy sheet was used, which is commonly utilized for auto parts. The junction strength characteristics in relation to the stirring speed and welding speed were studied in accordance with the friction stir welding rotation of the tool pin. Micro hardness measurements of A type and B type pins, for a welding speed of 400 mm/min and a tool rotational speed 3000 rpm, were obtained as Hv104 and Hv111, respectively. For a welding speed of 200 mm/min and a tool rotational speed of 2000 rpm, we obtained Hv48 and Hv50 for A and B type pins, respectively. Microstructure observation showed that the stirring portion was fine and uniform, which occurred because of its plastic deformation. In the thermomechanically affected zone, partial recrystallization was present because of the plastic deformation. The crystal grains in the heat affected zone were coarsened due to the heat generated by friction stir welding.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.05a
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• pp.53-62
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• 2004

A single layer latticed dome is one of the most efficient structures because of its low specivic gravity. For easily analyzing of a single layer latticed dome, joint system is assumed to be pin or rigid joint. However, its joint uses ball whose system has intermediate properties of pin and rigid joint. Therefore this study has a grasp of bending rigidity, stress and mechanical properties through experimental and analyzing method of the bolt inserted ball joint. To analyze the stress of bolt and sleeve, this study uses through 3D elastic contact and cubic element, and then the ball and the bolt are perfectly connected for easily analyzing Compared experimental results to F.E.M, each specimen has an error of less than 12 percent. In the results of stress distribution through F.E.M, stress occurs from bottom of bolt to top of sleeve, and most of tension appears on the bolt, also compression occurs from upper parts of the bolt to the sleeve. The assumption of bending stiffness in ball joint is well known that bolt resists only tension and upper sleeve resiss compression. The results of experiment and analysis have $7{\sim}56%$ error, assuring that upper part of bolt occurs of partial compression. In the result of modified assumption have $4{\sim}20%$ error.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.14 no.4
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• pp.322-326
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• 1992

Epiphora is overflow of tears due to obstruction of lacrimal duct. Dacryocystorhinostomy is the most common procedure to eliminate the epiphora secondary to complete or partial obstruction of the nasolacrimal duct. The procedure is to artificially create passage between lacrimal sac and nasal cavity. Especially, epiphora would be accompany often by nasolacrimal duct obstruction when trauma of oromaxillofacial area lead to nasal fracture, medial wall fracture of orbit. Therefore in this case there are many case to perform dacryocystorhinostomy because probing and tubing is difficult to resolve the epiphora. We performed 4 cases of dacryocystorhinostomy for adult nasolacrimal duct obstruction from May 1991 to October 1991. The results were very satisfactory in all the case. Epipora disappeared in all case.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.1
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• pp.85-90
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• 2012

The odontogenic myxoma is a relatively rare, benign tumor that occurs on the jaw. A 41 year-old man visited Seoul National University Dental Hospital because of swelling of the mandible. Clinical and radiographic evaluation showed a huge mass invading most of the mandible. After biopsy, he was diagnosed with odontogenic myxoma. For resection of the lesion, partial mandibulectomy and reconstruction with a vascularized fibular free flap was done. The result showed successful removal of the lesion. Reconstruction resulted in satisfactory functional and esthetic outcomes. We conclude that huge benign neoplasms such as odontogenic myxomas can be successfully treated by using a wide margin of resection followed by vascularized fibular free flap reconstruction.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.29 no.3
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• pp.227-232
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• 2007

The radial forearm fasciocutaneous flap(RFFF) is a well-known flap for the reconstruction of oral and maxillofacial defects. It was first described by Yang et al. in 1981 and Soutar et al. developed it for the reconstruction of intraoral defect. RFFF provides a reliable, thin, and pliable soft tissue/skin paddle that is amenable to sensate reconstruction. It also has a long vascular pedicle that can be anastomosed to any vessel in either the ipsilateral or contralateral neck. However, split thickness skin graft(STSG) is most commonly used to cover the donor site, and a variety of donor site complications have been reported, including delayed healing, swelling of the hand, persistent wrist stiffness, reduced hand strength, and partial loss of the graft with exposure of the forearm flexor tendon. Various methods for donor site repair in addition to STSG have been developed and practiced to minimize both functional and esthetic morbidity, such as direct closure, V-Y closure, full thickness skin graft, tissue expansion, acellular dermal graft. We got a good result of using artificial dermis($Terudermis^{(R)}$) and secondary STSG for the repair of RFFF donor site defect esthetically and report with a review of literature.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.37
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• pp.5.1-5.4
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• 2015

Dry eye syndrome is a relatively common disease of the tears and ocular surfaces that results in discomfort, visual disturbance, and tear film instability with possible damage to the ocular surfaces. Microvascular submandibular gland (SMG) transfer offers a surgical alternative for a permanent autologous substitution of tears using the basal secretion of a transplanted SMG. Long-term follow-up reveals that this technique is a lasting and effective solution for patients with severe dry eye syndrome. The uncomfortable symptoms were relieved, and the frequency of use of pharmaceutical tear substitutes was reduced. Objective examination showed significant improvement in tear film and some features of ocular surface such as breakup time of tear film and corneal staining. Patients may suffer from obstruction of Wharton's duct or epiphora after surgery. Activation of secretion-related receptors could improve the early hypofunction of the denervated SMG and prevent the duct obstruction. Reduction surgery, partial SMG transplantation, uses of atropine gel or Botulinum toxin A could be the choices of treatment for epiphora.

• Archives of Plastic Surgery
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• v.36 no.6
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• pp.779-783
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• 2009

Purpose: Male hypertrophic nipples can lead to psychological distress and physical discomfort. The authors present a new technique of male nipple reduction and describe its advantages Methods: The neonipple is designed to reduce diameter and height of nipple while preserving the subdermal plexus. After the central wedge excision, additional four triangular section of nipple skin is excised. One of the remaining two flaps is amputated partially and both flaps were approximated using 4 - 0 PDS and 6 - 0 Nylon sutures. Results: Between December of 2007 and January of 2009, 52 nipple reductions were performed in 30 male patients(mean = 29.5 years). Postoperative recovery was rapid and few complications were encountered. The mean diameter of the hypertrophic nipple was $9.1{\pm}2.5mm$(range, 7 to 15 mm). The mean diameter of the neonipple was $5.0{\pm}0.7mm$(range, 4 to 6 mm), with an average reduction of $3.8{\pm}0.6mm$(range, 2 to 11 mm). At follow-up, the neonipple had a natural appearance, with less projection and an inconspicuous scar. Conclusion: The wedge and triangular skin excision and partial amputation are easy to perform and yields consistent results. This technique decreases both the diameter and height of any size nipple and can be modified to meet patient preferences.

• Journal of Trauma and Injury
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• v.23 no.2
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• pp.157-162
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• 2010

Purpose: Free flap reconstruction in the pediatric population is difficult. However, microsurgery has had remarkable success rates in children. The aim of study is to present our clinical experience using free flap for reconstruction of soft tissue defects in children and to describe long-term follow-up results. Methods: Between June 2002 and July 2010, 30 cases of pediatric reconstruction were performed with free flap. The authors analyzed several items, such as the kind of flap, associated complications, and growth problems. Results: Among the 30 cases, 21 cases were due to traffic accidents, 5 to cancer, and 4 to falls and other soft tissue defects. The lower leg and foot were the most common sites of the lesion. In the free flap operations we have done, 20 cases involved an anterolateral thigh perforator free flap, 6 a superficial circumflex iliac perforator free flap, and 4 an upper medial thigh perforator free flap. In early postoperative complications, partial necrosis was seen in 2 cases, infection in 1 case, and the hematoma in 1 case. A satisfactory success rate and functional results were achieved. Conclusion: Free flap reconstruction in children allows satisfactory function with no significant effect on growth. Free flaps are regarded as the primary choice for selective pediatric reconstructive cases.

• Archives of Reconstructive Microsurgery
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• v.24 no.1
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• pp.28-31
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• 2015

A case report of a patient who developed radiation-induced sarcoma in the left chest wall is presented. The patient had partial mastectomy and adjuvant radiation therapy (total dose, 5,220 cGy) and chemotherapy. Five years later, she visited with rapidly growing mass with central ulceration in the irradiated chest wall. The mass was diagnosed as malignant fibrous histiocytoma. The chest wall mass resected en bloc ($23{\times}18cm$) including five consecutive ribs. After the defected thoracic cage was reinforced using a polytetrafluoroethylene patch, omental flap and split thickness skin graft was done for soft tissue coverage. We applied negative pressure wound closer system for effective suction of omeantal exudate. The wound healed without complications. The patient suffered no perioperative pulmonary complications. Pulmonary function tests showed no significant changes. Each of Gore-Tex, omental flap, negative pressure wound therapy and skin graft is widely used method. However, If these methods are used in combination, we can reconstruct the large defect of chest wall including multiple ribs without any repiratory function problems.

• Journal of Technologic Dentistry
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• v.21 no.1
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• pp.77-85
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• 1999

When producing partial denture using a Chrome-cobalt alloy being used universally, 45 pattern of them to compare casting characters according to 5 burying methods(special ring method, plastic ring method, general metal ring method) and 5 casting directions(straight, upper, lower, left and right directions) were compared and evaluated. The results were as follows : 1. The comparison of casting characters in accordance with burying type shows that the special ring method to install blind air vent using utility wax was the highest rate of 76.9%, followed by 69.1% of the plastic ring to cast without ring and 61.1% of the metal ring method being used universally respectively. Namely the special ring method was best. The significant level was P<0.05 statistically. 2. The comparison of casting character in accordance with casting directions shows that the straight casting was the highest of 77.9%, and followed by right casting of 74.2%, left casting of 66.7%, upper casting of 63.5%, and lower casting of 62.9% respectively, Namely the straight casting was best.