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1.
Sensors (Basel) ; 23(6)2023 Mar 20.
Article in English | MEDLINE | ID: mdl-36991981

ABSTRACT

Tracking unmanned aerial vehicles (UAVs) in outdoor scenes poses significant challenges due to their dynamic motion, diverse sizes, and changes in appearance. This paper proposes an efficient hybrid tracking method for UAVs, comprising a detector, tracker, and integrator. The integrator combines detection and tracking, and updates the target's features online while tracking, thereby addressing the aforementioned challenges. The online update mechanism ensures robust tracking by handling object deformation, diverse types of UAVs, and changes in background. We conducted experiments on custom and public UAV datasets to train the deep learning-based detector and evaluate the tracking methods, including the commonly used UAV123 and UAVL datasets, to demonstrate generalizability. The experimental results show the effectiveness and robustness of our proposed method under challenging conditions, such as out-of-view and low-resolution scenarios, and demonstrate its performance in UAV detection tasks.

2.
Sensors (Basel) ; 21(7)2021 Apr 02.
Article in English | MEDLINE | ID: mdl-33918491

ABSTRACT

This study proposes an entire hardware and software architecture from operator input to motor command for the autonomous area coverage mission using multiple unmanned aerial vehicles. Despite the rapid growth of commercial drone services, there are many limitations on operations, such as a low decision-making autonomy and the need for experienced operators to intervene in the whole process. For performing the area coverage mission more efficiently and autonomously, this study newly designs an optimization problem that allocates waypoints created to cover that area to unmanned aerial vehicles. With an optimized list of waypoints, unmanned aerial vehicles can fill the given areas with their footprints in a minimal amount of time and do not overlap each other during the mission. In addition, this study performs both various simulations for quantitative analysis and an outdoor experiment through real hardware implementation in order to verify the performance sufficiently. The methodologies developed in this study could be applied to endless applications using unmanned aerial vehicles equipped with mission-specific sensors.

3.
Opt Express ; 23(16): 21243-53, 2015 Aug 10.
Article in English | MEDLINE | ID: mdl-26367973

ABSTRACT

In situ direct observation of the lasing process in a cholesteric liquid crystal (CLC) laser array using a CMOS camera was used to investigate discontinuous laser tuning in a parallel CLC cell. In accordance with the discontinuous pitch change by thermal energy transfer, at the same time the laser wavelength undergoes an immediate and discontinuous shift. And we found out the reason why the CLC phase has domain textures. And this work develops a simple active tunable laser array by forming a spatial temperature gradient along a wedge CLC cell. With this new strategy, only just about 7 nm laser tuning range at room temperature is extremely widened over the 105 nm wavelength range with about 0.2 nm tuning resolution. Furthermore, there is no aging effect because the employed CLC array has only one chiral molecular concentration. This strategy could be used in a practical CLC laser device application.

4.
Sensors (Basel) ; 15(3): 5935-81, 2015 Mar 11.
Article in English | MEDLINE | ID: mdl-25769050

ABSTRACT

Gaze tracking systems usually utilize near-infrared (NIR) lights and NIR cameras, and the performance of such systems is mainly affected by external light sources that include NIR components. This is ascribed to the production of additional (imposter) corneal specular reflection (SR) caused by the external light, which makes it difficult to discriminate between the correct SR as caused by the NIR illuminator of the gaze tracking system and the imposter SR. To overcome this problem, a new method is proposed for determining the correct SR in the presence of external light based on the relationship between the corneal SR and the pupil movable area with the relative position of the pupil and the corneal SR. The experimental results showed that the proposed method makes the gaze tracking system robust to the existence of external light.


Subject(s)
Cornea/physiology , Eye Movements/physiology , Fixation, Ocular , Humans , Light , Lighting
5.
Sensors (Basel) ; 13(10): 13439-63, 2013 Oct 07.
Article in English | MEDLINE | ID: mdl-24105351

ABSTRACT

We propose a new remote gaze tracking system as an intelligent TV interface. Our research is novel in the following three ways: first, because a user can sit at various positions in front of a large display, the capture volume of the gaze tracking system should be greater, so the proposed system includes two cameras which can be moved simultaneously by panning and tilting mechanisms, a wide view camera (WVC) for detecting eye position and an auto-focusing narrow view camera (NVC) for capturing enlarged eye images. Second, in order to remove the complicated calibration between the WVC and NVC and to enhance the capture speed of the NVC, these two cameras are combined in a parallel structure. Third, the auto-focusing of the NVC is achieved on the basis of both the user's facial width in the WVC image and a focus score calculated on the eye image of the NVC. Experimental results showed that the proposed system can be operated with a gaze tracking accuracy of ±0.737°~±0.775° and a speed of 5~10 frames/s.


Subject(s)
Computer Terminals , Data Display , Fixation, Ocular/physiology , Pattern Recognition, Automated/methods , Photography/instrumentation , Remote Sensing Technology/instrumentation , Television/instrumentation , Equipment Design , Equipment Failure Analysis , Humans , Reproducibility of Results , Sensitivity and Specificity , User-Computer Interface
6.
Biomol Ther (Seoul) ; 20(2): 234-8, 2012 Mar.
Article in English | MEDLINE | ID: mdl-24116301

ABSTRACT

Propofol is an anesthetic commonly used to provide sedation or to induce and maintain an anesthetic stated. However, there are reports which indicate propofol may cause psychological dependence or be abused. In the present study, we used various behavioral tests including climbing test, jumping test, conditioned place preference, and self-administration test to assess the dependence potential and abuse liability of propofol compared to a positive control (methamphetamine) or a negative control (saline or intralipid). Among the tests, the conditioned place preference test was conducted with a biased method, and the selfadministration test was performed under a fixed ratio (FR) 1 schedule, 1 h per session. No difference was found in the climbing test and jumping test, but propofol (30 mg/kg, i.p.) increased the rewarding effect in the conditioned place preference test, and it showed a positive reinforcing effect compared to the vehicle. These results indicate that propofol tends to show psychological dependence rather than physical dependence, and it seems not to be related with dopaminergic system.

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