수중로봇의 자율 내비게이션을 위한 영상기반의 물체인식 및 경로생성

학위논문(석사) - 한국과학기술원 : 로봇공학학제전공, 2011.2, [ v, 43 p. ]Underwater robots have been an emerging research area at the intersection of the field of robotics and oceanic engineering. Their applications include environmental monitoring, oceanographic mapping, and infrastructure inspections in deep sea. Performing these tasks, the ability of autonomous navigation is the key to a success, especially with the limited communications in underwater environments. Considering the highly dynamic and three dimensional environments, the autonomous navigation technologies including path planning and tracking have been one of the interesting but challenging tasks in the field of study. Cameras have not been at the center of attention as an underwater sensor due to the limited detection ranges and the poor visibility. Use of visual data from cameras is still an attractive method for underwater sensing and it is especially effective in the close range detections. In this thesis, the vision-based navigation techniques for underwater robots have been studied in depth. In order to overcome the limitations of cameras and to make use of the full advantages of image data, a number of approaches have been taken. The topics include color restoration algorithm for the degraded underwater images, detection and tracking methods for underwater targets, and robot guidance algorithms based on the visual detection results. The feasibilities of the proposed algorithms have been shown in the experiments with an underwater robot platform and the results have been analyzed both qualitatively and quantitatively.한국과학기술원 : 로봇공학학제전공

Follow-up study on mortality in Korean stroke patients

Stroke is the most common cause of death as single-diseases in South Korea. And it generates additional medical cost through high incidence of related disabilities and complications, which would become more important with the rapid aging process in Korean society. This study was preformed to identify stroke patients' mortality and its associated factors. Patients diagnosed as stroke (ICD-10 code 160-163) in 2003 were identified. Their follow-up mortality rate in 5 years and related factors (stroke type, sex, age, type of first admission hospital, comorbidity score) were analyzed using national health insurance claim data and national cause of death statistics. The mortality rate peaked in early days after attack, and decreased subsequently as the survive time gets longer. The mortality rate was higher in hemorrhagic stroke than ischemic stroke, in female than male, with the older age, and with the higher comorbidity score. It is recommended that the early intervention at general hospital or tertiary referral hospital should be promoted to decrease the mortality rate in stroke patients, and related quality assurance programs have to be enforced.N