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Object Recognition from Spherical Camera Images Based on YOLOv3
Tomohiro Kai,Humin Lu,Tohru Kamiya 제어로봇시스템학회 2020 제어로봇시스템학회 국제학술대회 논문집 Vol.2020 No.10
The aging of Japan is remarkable, and attention has been focused on the use and utilization of assistive devices. One of them is electric wheelchair, which enables physical disability people to easily operate it using a handle or a joystick. However, accidents are occurring frequently with increasing demand by using electric wheelchair. Therefore, developing an autonomous electric wheelchair is required to reduce accidents such as maneuvering mistakes, reduce the accident rate, improve convenience, and reduce the burden on caregivers. In this paper, we focus on the recognition of obstacles and use panoramic images obtained from a spherical camera that can easily handle information from all directions at low cost. A spherical camera is attached to an electric wheelchair, and images are cut out from the sequential images obtained by running. For image analysis, YOLOv3, which has been successful in the field of image recognition in recent years, is used. In the proposed method, considering the distortion of the image caused by using the spherical camera, the improvement of the model of YOLOv3 is examined, and the validity with the actual data is verified.
Testing the Copernican Principle with the kSZ Effect
유철문,Tomohiro Kai,Ken-ichi Nakao,Misao Sasaki 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.31
The kinematic Sunyaev-Zel’dovich (kSZ) effect in a Lemˆıtre-Tolman-Bondi (LTB) universe is discussed. We use the LTB universe model whose distance redshift relation coincides with the concordance ∧CDM model. The physical degrees of freedom on the last scattering surface (LSS) are fixed by using Gamow’s criterion and other additional convenient conditions. We simulate the kSZ effect by solving the null geodesic equations numerically. The observational results with adiabatic inhomogeneities on the LSS seem to be difficult to explain. This difficulty would be resolved by introducing an inhomogeneity of the matter-to-photon ratio on the LSS.
(Astrophysics and Cosmology) Solving the Inverse Problem with Inhomogeneous Universes
Yoo, Chul-Moon,Kai, Tomohiro,Nakao, Ken-ichi Yukawa Institute for Theoretical Physics and the P 2008 Progress of theoretical physics Vol.120 No.5
We construct the Lema?tre-Tolman-Bondi (LTB) dust universe whose distance-redshift relation is equivalent to that in the concordance Λ cold dark matter (ΛCDM) cosmological model. In our model, the density distribution and velocity field are not homogeneous, whereas the big-bang time is uniform, which implies that the universe is homogeneous at its beginning. We also study the effects of local clumpiness in the density distribution as well as the effects of large-scale inhomogeneities on the distance-redshift relation, and show that these effects may reduce the amplitude of large-scale inhomogeneities necessary for having a distance-redshift relation that is the same as that of the concordance ΛCDM universe. We also study the temporal variation of the cosmological redshift and show that, by the observation of this quantity, we can distinguish our LTB universe model from the concordance ΛCDM model, even if their redshift-distance relations are equivalent to each other.