• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.788-791
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• 2004

This paper presents a general description of single and dual contact tooling systems, finite element analysis, and discussions on the application of the system to the 5-head router machine which is in particular for aerospace components. This study has been performed as part of the development of the new generation 5-head router machine which is designed for high productivity. Such high productivity in essence requires high speed rotation and multiple spindles in one machine. The high speed rotation may exceed a range in a conventional single contact tooling system. The conventional tooling system is reevaluated in comparison with the dual-contact system. Finite element analysis using simplified spindle models compares major differences in the two systems. Some problems in the application to the 5-head router machine are discussed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.589-590
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• 2012

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.805-806
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• 2013

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.660-665
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• 2006

This paper presents a finite element method to analyze the free and forced vibration of a hard disk drive (HDD) considering the flexibility of a spinning disk-spindle with fluid dynamic bearings (FDBs), an actuator with pivot bearings, an air bearing between head-disk interface and the base with complicated geometry. Finite element equation of each component is consistently derived with the satisfaction of the geometric compatibility of the internal boundary between each component. The spinning disk, hub and FDBs are modeled by annular sector elements, beam elements and stiffness and damping elements, respectively. The actuator am, E-block, suspension and base plate are modeled by tetrahedral elements. The pivot bearing in the actuator and the air bearing between head-disk interfaces are modeled by the stiffness element with five degrees of freedom and the axial stiffness, respectively. A global matrix equation obtained by assembling the finite element equations of each substructure is transformed to a state-space matrix-vector equation, and both damped natural frequencies and modal damping ratios are calculated by solving the associated eigenvalue problem with the restarted Arnoldi iteration method. Modal and shock testing are performed to show that the proposed method well predicts the vibration characteristics of a HDD.

• Archives of Plastic Surgery
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• 제39권2호
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• pp.158-161
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• 2012

Myopericytoma is a benign tumor that is composed of myoid-appearing oval to spindle-shaped cells with a concentric perivascular pattern of growth. The tumor is morphologically heterogeneous and can exhibit a broad histologic spectrum. We describe a case of multiple myopericytoma occurring in the head and neck skin region with involvement of the parotid gland where it is known to occur very rarely. A 40-year-old woman noticed multiple enlarging, painless, round-shaped masses on her left cheek. The patient had experienced a similar lesion of the same area 8 years earlier which was completely excised and the pathological diagnosis was spindle cell type myoepithelioma. On a computed tomographic image, one mass involved the superficial parotid gland and was well encapsulated. Excision of the facial masses and superficial parotidectomy with facial nerve preservation were performed. A diagnosis of myopericytoma was established in light of the immunohistochemical pattern with the histopathological findings. Over the 4-year follow-up period, there was no evidence of recurrence. As many perivascular myoid neoplasms share common morphologic features with myopericytoma, we should consider the differential diagnosis, and confirm the histological findings with appropriate immunohistochemical staining. After identifying myopericytoma, it should be treated with wide surgical excision to prevent local recurrence.

• Archives of Plastic Surgery
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• 제32권6호
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• pp.760-762
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• 2005

Synovial Sarcoma is the fourth most common sarcoma, accounting for 8-10 % of all sarcomas. Synovial sarcoma is highly malignant tumor of mesenchymal origin but rarely occurres in head and neck area. Less than 100 cases of synovial sarcoma occurring in head and neck area have been reported all over the world. Pathologically, there is two type of synovial sarcoma: monophasic variant is composed of only one cell type and "classic" (biphasic) synovial sarcoma has two cellular component, a spindle cell(fibrosarcoma-like) component and a pseudoepithelioma component. Recommended treatment is wide resection with negative margins. The role of chemotherapy and radiation therapy is controversial. We experienced a 42-year-old male patient with slowly enlarging, deep seated mass on right cheek. In the first operation, we suggested that the mass maybe benign tumor. But, initial excisional biopsy specimen of the primary lesion was consistent with synovial sarcoma. The final diagnosis was monophasic synovial sarcoma which was composed of spindle cells. Radical resection was performed two months later because remnant tumor was found on follow up MRI. No further treatment was done. There were no recurrence or metastasis on follow up MRI, chest CT and whole body bone scan after 15 months. This is a report of a rare case of synovial sarcoma of the face with a literature review.

• 대한두경부종양학회지
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• 제23권1호
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• pp.67-70
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• 2007

Myxoma is an uncertain mesenchymal cell origin, characterized by irregular round, stellate or spindle cells surrounded by the matrix containing abundant mucoid material and scant vascularity. Their occurrence in descending order of frequency is in the heart, subcutaneous tissue, bone and genitourinary tract. In the head and neck region, the most predilection sites are mandible and maxilla(more than 80%). Laryngeal myxoma is extremely rare：only 5 cases have been reported in the English literature. We report a rare case of laryngeal myxoma. A 60-year-old man with hoarseness visited the out-patient department. The mass was located between the vocal fold and the vocal ligament, filling with the left laryngeal ventricle. We planned the laryngo-microsurgery and successfully excised using $CO_2$ laser. The histopathologic finding revealed the myxoma. After 18 months of surgery, there is no evidence of recurrence and mucosal scarring in the vocal fold. This report is the first case of laryngeal myxoma involving the laryngeal ventricle and the true vocal cord together.

• 대한두경부종양학회지
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• 제32권2호
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• pp.9-13
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• 2016

Infantile myofibromatosis is a rare benign neoplasm which is usually found in males. Most cases of the infantile myofibromatosis are discovered before the age of two years and about half of cases are found at muscle, tendon, and soft tissue of head-neck region. However, it is especially uncommon that infantile myofibroma occurs at the pre-auricular area. In current case, we report a twenty two months old male patient with $2.5{\times}1.5cm$ sized pre-auricular mass at right side. It was surgically removed and histologically showed broad bundle of plump myoid spindle cells with eosinophilic cytoplasm and weakly positive smooth muscle actin expression in myoid cells. In three months of follow up, there was no recurrence.

• 한국정밀공학회지
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• 제16권6호
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• pp.58-65
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• 1999

The spinning machine has been developed for a bus and truck wheel disc which is manufactured by spinning process method. This machine has the mechanical structure with bed, 2-column, cross head, 2-vertical slide, 2-horizontal slide with forming roller, clamp slide and main spindle similar to large size vertical lathe. Main spindle attached the mandrel is rotated about 500rpm drived by 280kW power DC motor, and a rotating black material pressed on the mandrel with the clamp slide is spinformed by 2-forming rollers which are attached inner end of the 2-horizontal slides. The 2-vertical and 2-horizontal slides are actuated by the hydraulic cylinder which is controlled by the servo valve individially, and these servo valves are controlled by control signal of the CNC controller which is computed with position signal feedbacked from the encoder sensor. The developed machine can manufacture wheel disc of various section profile without mandrel change because section profile is easily modified using program editing in the CNC controller processor. The wheel disc manufactured by spinning process method has many advantages that the endurance is increased by 2 times and the weight is decreased by 30% compared with a conventional disc.

• 대한두경부종양학회지
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• 제36권2호
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• pp.37-40
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• 2020

Pleomorphic hyalinizing angiectatic tumor (PHAT) is a rare, low grade neoplasm which usually occurs in subcutaneous soft tissue. Histologically, it features ectatic blood filled vessels surrounded by hyalinized stroma and pleomorphic spindle cells. Clinically and histologically, PHAT could be misdiagnosed as such tumor as neurogenic tumor, malignant fibrous histiocytoma. About 100 cases of PHAT have been reported so far, and it is even rarer in head and neck area. We experienced a case of PHAT in 41-year-old male with several months of history of gradually enlarging neck mass which was surgically removed by wide excision.