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라요한,박선영,임수아,김지영,정낙균,조빈 대한자기공명의과학회 2016 Investigative Magnetic Resonance Imaging Vol.20 No.3
Purpose: To identify magnetic resonance imaging (MRI) findings of leukemic infiltration of optic nerve and optic neuritis in leukemic patients with emphasis of clinical findings as reference standard to differentiate them. Materials and Methods: MRI and clinical findings of 7 patients diagnosed as leukemic infiltration of optic nerve (n = 5) and optic neuritis (n = 2) in our institution between July 2006 and August 2015were reviewed retrospectively. In particular, MR imaging findings involved perineural enhancement and thickening of optic nerve and its degree, signal intensity, laterality (unilateral/bilateral), intraconal fat infiltration and its degree, and associated central nervous system abnormalities. Results: Of 5 cases of leukemic infiltration of optic nerve, 4 cases showed positive cerebrospinal fluid (CSF) study for leukemia relapse and 1 case was positive on bone marrow (BM) biopsy only. Moreover, of 5 leukemic infiltration of optic nerve, 2 cases showed the most specific MR findings for leukemic central nervous system involvement including 1 prominent leptomeningeal enhancement and 1 chloroma. However, other MR imaging findings of the patients with leukemic infiltration or optic neuritis such as thickening and perineural enhancement of optic nerves are overlapped. Conclusion: Enhancement and thickening of optic nerve were overlapped MR findings in leukemic infiltration of optic nerve and optic neuritis. Our findings suggest that enhancing optic nerve thickening with associated central nervous system MR abnormality favors the diagnosis of leukemic infiltration of optic nerve, especially in patients with history of acute lymphoblastic leukemia. However, CSF and BM study were required for differentiation between leukemic infiltration of optic nerve and optic neuritis.
라요한(Yohan La),최한순(Hansoon Choi),윤태준(Taejoon Yoon),김현건(Hyungun Kim),남윤수(Yoonsu Nam) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.5
This paper is about real-time simulation of wind turbine. Wind turbine is controlled using GH Bladed Hardware Test Module and External control. First, this paper explains that default configuration of Hardware interface. Next, mention about Preparation and Concepts for driving Bladed Hardware Test. The control system consists of torque control and pitch control. I/O port between Bladed Hardware Test and external control connection to the controls. Finally, some simulation results for external control control to a MW wind turbine are discussed in this paper.
NREL 5MW 풍력터빈의 블레이드 하중 저감을 위한 개별피치제어
라요한(Yo Han La),남윤수(Yoon Su Nam),손재훈(Son Jae Hoon) 대한기계학회 2012 大韓機械學會論文集A Vol.36 No.11
풍력터빈이 점차 대형화 되면서 로터 직경도 점차 커지고 있다. 로터 블레이드는 윈드시어와 타워교란 효과로부터 기계적 하중을 받게 된다. 이러한 기계적 하중은 풍력터빈의 수명을 단축시킨다. 따라서, 풍력터빈의 크기가 커짐에 따라 기계적 하중 완화를 위한 풍력터빈 제어 시스템 설계가 중요하다. 본 논문에서는 로터 블레이드의 기계적 하중 저감을 위한 개별 피치 제어에 대해 소개하고 IPC 성능 검증을 위해 시뮬레이션을 통하여 논의한다. As the size of a wind turbine increases, the rotor diameter increases. Rotor blades experience mechanical loads caused by the wind shear and the tower shadow effect. These mechanical loads reduce the life of the wind turbine. Therefore, with increasing size of the wind turbine, wind turbine control system design for the mitigation of mechanical loads is important. In this study, Individual Pitch Control in introduced for reducing the mechanical loads of rotor blades, and a simulation for IPC performance verification is discussed.
The effect of torque scheduling on the performance and mechanical loads of a wind turbine
남윤수,라요한,손재훈,오용운,조장환 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.5
The generator torque control loop of a multi-MW wind turbine consists of three operational regions, i.e. a max Cp region, a transientregion around the rated rotor speed, and a power regulation region. The performance and mechanical stress on the wind turbine structureare closely related with how the torque schedule is mechanized in the transient and above-rated regions. Using a drive train model, theclosed loop dynamic characteristics for different torque schedules were analyzed. It is found that the slope of the torque for the rotorspeed in the transient region is the major factor which determines the performance and mechanical loading of the wind turbine. The effectof using a variable torque instead of the fixed rated torque in the above-rated region is also analyzed.
남윤수(Yoonsu Nam),라요한(Yo Han La) 한국항공우주학회 2013 韓國航空宇宙學會誌 Vol.41 No.3
풍력터빈이 점차 대형화 되면서 로터 직경도 점차 커지고 있다. 로터 블레이드는 윈드시어와 타워 교란 효과로부터 기계적 하중을 받게 된다. 이러한 기계적 하중은 풍력터빈의 수명을 단축시킨다. 풍력터빈의 크기가 커짐에 따라 기계적 하중 완화를 위한 풍력터빈 제어 시스템 설계가 중요하다. 본 논문에서는 로터 블레이드의 기계적 하중 저감을 위한 천이영역에서의 개별 피치 제어에 대해 소개하고 IPC 성능 검증을 위해 시뮬레이션을 통하여 논의한다. Rotor blades experience mechanical loads caused by the turbulent wind shear and an impulse-like wind due to the tower shadow effect. These mechanical loads shorten the life of wind turbine. As the size of wind turbine gets bigger, a control system design for mitigating mechanical loads becomes more important. In this paper, individual pitch control(IPC) for the mechanical loads reduction of rotor blades in a transition wind speed region is introduced, and simulation results verifying IPC performance are discussed.
오용운(Yong Oon Oh),백인수(In Su Paek),남윤수(Yoon Su Nam),라요한(Yo Han La) 한국태양에너지학회 2014 한국태양에너지학회 논문집 Vol.34 No.1
A study on the available power of a wind turbine to be used for wind farm control was performed in this study, To accurately estimate the available power it is important to obtain a suitable wind which represents the three dimensional wind that the wind turbine rotor faces and also used to calculate the power. For this, two different models, the equivalent wind and the wind speed estimator were constructed and used for dynamic simulation using matlab simulink. From the comparison of the simulation result with that from a commercial code based on multi-body dynamics, it was found that using the hub height wind to estimate available power from a turbine results in high frequency components in the power prediction which is, in reality, filtered out by the rotor inertia. It was also found that the wind speed estimator yielded less error than the equivalent wind when compared with the result from the commercial code.