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부분용적효과를 고려한 확산텐서영상에 대한 관심영역 분석 연구
최우혁,윤의철,Choi, Woohyuk,Yoon, Uicheul 대한의용생체공학회 2016 의공학회지 Vol.37 No.2
In this study, we proposed ameliorated method for region of interest (ROI) study to improve its accuracy using partial volume effect (PVE). PVE which arose in volumetric images when more than one tissue type occur in a voxel, could be used to reduce an amount of gray matter and cerebrospinal fluid within ROI of diffusion tensor image (DTI). In order to define ROIs, individual b0 image was spatially aligned to the JHU DTI-based atlas using linear and non-linear registration (http://cmrm.med.jhmi.edu/). Fractional anisotropy (FA) and mean diffusivity (MD) maps were estimated by fitting diffusion tensor model to each image voxel, and their mean values were computed within each ROI with PVE threshold. Participants of this study consisted of 20 healthy controls, 27 Alzheimer's disease and 27 normal-pressure hydrocephalus patients. The result showed that the mean FA and MD of each ROI were increased and decreased respectively, but standard deviation was significantly decreased when PVE was applied. In conclusion, the proposed method suggested that PVE was indispensable to improve an accuracy of DTI ROI study.
애드혹을 이용한 자동차 네트워크에서 이동성에 따른 네트워크 성능 분석
김재현(Jaehyun Kim),최우혁(Woohyuk Choi),황윤일(Yunil Hwang),김태환(Taehwan Kim),한우진(Woojin Han),장주욱(Juwook Jang),엄재용(Jaeyong Um),임준채(JunChae Lim) 한국정보과학회 2005 한국정보과학회 학술발표논문집 Vol.32 No.1
본 논문은 애드혹을 이용한 자동차간 네트워크에서 도심 및 고속도로에서 소규모로 그룹을 지어 이동할 때의 네트워크 성능을 분석한다. 자동차를 위한 무선 네트워크를 구축하기 위하여 IEEE 802.11b를 이용한 애드혹 네트워크를 사용한다. 그리고 이러한 네트워크에서 다양한 이동성 환경에서 IEEE 802.11b를 이용한 네트워크의 성능을 분석한다. 이를 위하여 네트워크 시뮬레이터인 OPNET을 이용하여 실제 자동차가 이동하는 이동성 모델을 적용한 후 TCP와 UDP를 이용하여 대용량의 데이터를 전송할 때의 네트워크 성능을 측정한다. 또한 실제 자동차에 애드혹 네트워크를 구축하여 TCP와 UDP를 이용한 대용량의 자료를 주고받을 때의 네트워크 성능을 측정합니다.
서현(Hyeon Seo),최우혁(WooHyuk Choi),이은희(Eun-Hee Lee) 한국정보기술학회 2022 한국정보기술학회논문지 Vol.20 No.12
Focused ultrasound with microbubbles is a promising therapeutic technique for the blood-brain barrier disruption and enabling the delivery of drugs. Microbubbles are excited to oscillation, and it is categorized into stable cavitation which is oscillate periodically and inertial cavitation which release high levels of energy at high acoustic pressure. Inertial cavitation may cause mechanical damage to the surrounding tissues and thus it is crucial to predict the stable cavitation pressure range. Here, we performed nonlinear cavitation modeling coupled with a 3D acoustic simulation capable of considering transducer structure. Using a 3D pressure field validated against empirical data, we calculated a stable cavitation range under 0.34 MPa following 1.2 MHz insonation. The Proposed model is expected to construct safe and successful protocols for therapeutic delivery using focused ultrasound because both transducer structure and ultrasound focusing through the skull can be considered.