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권오현,김정득,박상준,김의중,윤성문,Kwon, O Hyun,Kim, Jung Deuk,Park, Sang June,Kim, Eui Joong,Yoon, Sung Moon 대한신경외과학회 2001 Journal of Korean neurosurgical society Vol.30 No.11
Mesenchymal chondrosarcoma is a rare tumor occurring in both bone and soft tissues and exhibits characteristic of a malignant nature. The authors experienced a case of mesenchymal chondrosarcoma occurring in a 23-year-old woman which had invaded the cervical spine. The patient presented with severe both shoulder pain, left upper extremity weakness(Grade IV) and paresthesia at admission. Radiologic studies of the cervial spine showed an aggressive osteolysis of C4 vertebral body, pedicle and lamina with compression of the spinal cord posteriorly on C3, C4, C5 levels. The tumor was totally removed by a combined anterior and posterior approach. The removed vertebral body was replaced with autogenous bone and stabilized by Codman locking plate symtem. The pathological examination showed characteristic of mesenchymal chondrosarcoma.previous symptoms well improved postoperatively. The authors present a case of mesenchymal chondrosarcoma with review of literature.
권오현(O-Hyun Kwon),변선우(Seon-Woo Byun),노진호(Jin-Ho Roh) 한국항공우주학회 2018 韓國航空宇宙學會誌 Vol.46 No.1
풍력발전기의 효율을 증가시키기 위하여 피치제어가 주로 사용되어 왔으나 피로파괴와 효율의 감소를 일으키는 날개의 국부적인 유동을 제어할 수 없는 단점이 있다. 본 논문에서는 기존의 풍력발전기 블레이드에 합성제트 구동기 모듈을 설치하여 국부 유동을 제어하고 날개의 공력성능을 향상시키고자 한다. 합성제트 구동기는 작은 구멍을 통해 유체를 흡입/분출하여 유동 박리를 지연시켜 공력성능을 향상시킨다. 압전디스크를 사용하여 탈부착이 가능한 합성제트 구동기 모듈을 제작하고 풍동실험을 통해 오리피스 형상과 합성제트 속도에 따른 공력성능을 측정하였다. 직사각형 오리피스 형상을 사용하고 합성제트 속도가 커질수록 날개의 항력이 감소하고 양력이 증가하는 것을 확인하였다. The size of commercial wind turbines has been increased. Generally, the pitch control is used to increase the efficiency of wind turbine. However, the pitch control has difficulty to control the local unsteady flow control which makes fatigue load and decreases the efficiency. In this research, Synthetic Jet Actuators(SJAs) are manufactured and applied into a wing section to delay flow separation and increase aerodynamic performances. The SJAs as a kind of zero-net mass-flux actuators injects and removes fluid through a small orifice with a given frequency. The SJA modules actuated by piezoelectric disks are manufactured and the aerodynamic performances are measured according to the shape of the orifice and the velocity of the jets through the wind tunnel test. It is confirmed that as the velocity of the jets are increased using rectangular shape orifice, drag force is decreased and lift force in increased.