Yonghoon Cho

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We have developed monolithic white light emitting diodes (LEDs), which consist of planar planes and nano size hexagonal pyramids structure. The white spectrum is achieved by blue and yellow emissions from the InGaN multi quantum wells (MQWs) on the planar c-planes and on the nano-pyramids, respectively. The color temperature is tuned from 3600K to 6400K by(More)
This study addresses autonomous detection and tracking of a surface ship using a monocular camera mounted on an unmanned surface vehicle (USV). Automatic feature extraction and tracking filter algorithms are used for vision-based detection and tracking in real-time. For target tracking, the bearing and range to the target ship with respect to the own ship(More)
For safe ship navigation, efficient and reliable collision assessment and trajectory estimation are required. This study addresses the problem of collision probability assessment between surface ships considering their maneuver intentions. An extended Kalman filter is used for trajectory estimation, and the collision probability and the probability of(More)
This paper addresses relative navigation of unmanned surface vehicles (USVs) under marine floating structures where GPS signals are severely deteriorated or not available. An onboard 3D lidar collects point cloud of the structures and planar surfaces of their column structures are detected and used as landmark features in the framework of simultaneous(More)
We report a white emission from InGaN multi-quantum wells (MQWs) on micro size c-planes and nano size hexagonal pyramids hybrid structure. Despite simultaneous growth, we achieve two different emission peaks of 461 nm and 568 from the MQWs on the c-planes and on the nano-pyramids, respectively. Using the structure, we achieve a white emission spectrum which(More)
This study presents the development of vision-based techniques for autonomous collision avoidance by an unmanned surface ship using an onboard monocular camera. In order to determine the initiation of an evasive maneuver, the range and bearing measurements of each target traffic ship with respect to the observer (e.g., own ship) need to be provided for(More)
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