• Journal of the Korean Society for Precision Engineering
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• v.31 no.10
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• pp.929-934
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• 2014

Reaction force compensation (RFC) mechanism can relieve the vibration of base system caused by acceleration and deceleration of mover. In this paper, we propose a new passive RFC mechanism with a movable additional mass to reduce vibration of the system base as well as displacement of the magnet track. First, equation of motion for the new passive RFC mechanism is derived and simulated to tune design parameters such as masses and spring coefficients. Simulation results show that the vibration of the system base of the stage with the new RFC mechanism.

• Korean Journal of Head & Neck Oncology
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• v.37 no.1
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• pp.33-37
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• 2021

Intraosseous hemangioma is a rare, benign vascular tumor of endothelial origin. It accounts for fewer than 1% of all hemangiomas, and very rarely occurs in the face. Intraosseous hemangioma usually presents as an asymptomatic lesion, but symptoms can occur due to the mass effect. The authors describe a case of intraosseous hemangioma of the zygoma with a review of the relevant literature. A 44-year-old man presented with a chief complaint of painless swelling on the left zygomatic region that had been slowly growing for the past year. On physical examination, a hard, non-movable mass in a deep layer was palpated. On computed tomography performed to evaluate its layers and extent, trabeculation was found inside the mass, but the lack of destruction of the surrounding bone suggested that the mass was benign. Complete surgical excision was performed under local anesthesia. After complete excision of the mass, slight erosions remained on the cortical bone of the zygoma, but because it was small enough not to cause a facial deformity such as depression or asymmetry, no additional reconstructive procedure was performed. There were no symptoms or recurrence during a 8-month follow-up period.