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CURRENT STATUS OF THE EAVN EXPERIMENTS
HAGIWARA, YOSHIAKI,AN, TAO,JUNG, TAEHYUN,RHO, DUK-GYOO,ZHANG, MING,HAO, LONGFEI,FUJISAWA, KENTA,YONEKURA, YOSHINORI,BAAN, WILLEM,KIM, JONGSOO,KOBAYASHI, HIDEYUKI The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2
VLBI experiments have been conducted by radio telescopes in the East Asia VLBI Network (EAVN) in which 14 telescopes in China, Japan, and Korea participated. One of the aims of the EAVN is to obtain higher angular resolution that is provided by the 6,000 km baseline between China and Japan and better sensitivity by adding large telescopes. Data were recorded at 1 a Gbps recording rate at all stations and processed on the Korea-Japan Joint VLBI Correlator (KJJVC) at the Korea-Japan Correlation Center (KJCC) after experiments. Fringes were obtained from these experiments conducted at 8 GHz and 22 GHz and post-correlation data analysis of the experiments is undergoing. The outcomes of these experiments open the possibility of conducting EAVN observations with global VLBI networks. In this presentation, the recent status of these experiments and future prospects are presented.
Yoshiaki Mizuchi,Tadashi Ogura,Young-Bok Kim,Yoshinobu Hagiwara,Yongwoon Choi 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10
In this study, we propose a measurement system consists of two pairs of multiple cameras mounted on a pan-tilt unit and a landmark installed on a target side. The purpose of the proposed system is to measure relative position and heading angle of a vessel to a target at a close distance, in order to reduce collision risks by automation of vessel positioning that requires high measurement accuracy and rate. To achieve such measurement, cameras that have wide sensing range and high angular resolution are used instead of GPS, radars, or laser sensors. The proposed system also has the ability of accurate and fast measurement of the distance and direction angle to a target by applying a simple and robust target detection method. The position and heading of a vessel are determined from two pairs of the distance and direction angle. To evaluate the measurement accuracy of the proposed system, we measured position and heading of the system relative to landmarks on several conditions including positional displacement and rotation. The experimental results demonstrate that the proposed system can be used for automation of vessel positioning at a close distance.
Monocular 3D Palm Posture Estimation Based on Feature-Points Robust against Finger Motion
Yoshiaki Mizuchi,Yoshinobu Hagiwara,Akimasa Suzuki,Hiroki Imamura,Yongwoon Choi 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10
The usability of wearable augmented reality (AR) systems would improve by letting users arbitrarily display virtual information on their palm and simultaneously manipulate it as tablet computers or smartphones. To realize such interaction between users and virtual information, we aim to robustly estimate 3-D palm posture against finger motion. This is based on the assumption that finger motion is separately estimated from palm posture and applied to manipulation of displayed information. In addition, the capability of electric sources, sensors, and processors are very limited in wearable computers. For this reason, by using a monocular camera and estimating palm posture from only a few image feature-points, we achieve an efficient estimation that satisfies real-time constraint on wearable computers. The accuracy and the robustness of our method are demonstrated by qualitative and quantitative comparison with a widely-used cardboard maker. Additionally, we confirmed that our method is run on a mobile computer at the average of 12.44 msec per frame.
Vision-based markerless measurement system for relative vessel positioning
Mizuchi, Yoshiaki,Ogura, Tadashi,Kim, Youngbok,Hagiwara, Yoshinobu,Choi, Yongwoon IET 2016 IET science, measurement & technology Vol.10 No.6
<P>The measurement of relative vessel positioning is important to prevent the risk of vessel collision or the deterioration of working efficiency. This study presents a vision-based system for measuring the relative position and heading between a vessel and a target object without the installation of transponders, reflectors, or markers. Such a markerless measurement system, which is not restricted by the presence or the absence of transponders, is a method of expanding feasible conditions for relative vessel positioning. The proposed system consists of multiple camera units that can measure the distance and direction between an initially designated point on a target object while keep track of the designated point. To evaluate the measurement performance for the proposed system, the authors conducted measurements by using a prototype system in water. The results demonstrated that the system can keep track of the designated points and accurately measure the position and heading of a vessel relative to a target object, despite the vessel's roll motion.</P>
Distance Measurement System using Stereo Camera for Automatic Ship Control
Tadashi Ogura,Yoshiaki Mizuchi,Yoshinobu Hagiwara,Youngbok Kim,Akimasa Suzuki,Yongwoon Choi,Kazuhiro Watanabe 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10
A long distance measurement system using a stereo camera mounted on a rotation control device is proposed for automatic ship control, and the performance of the system is presented to verify the usefulness of it. As a solution to prevent ship operators from maritime accidents owing to their strain for a long period, the distance measurement system is often required to automatically control the posture or berthing of a ship. Here, we discuss the system structure suitable for used environment and its experimental results. From the experiment conducted to imagine the distance measurement necessary to altering the posture and translational motion between a ship and its facilities, the average error for the range of 20 to 100 m was less than 1 percent.
Probabilistic Distributions of Plate Buckling Strength for Normal and Bridge High-performance Steels
Dang Viet Duc,Yoshiaki Okui,Koichi Hagiwara,Masatsugu Nagai 한국강구조학회 2013 International Journal of Steel Structures Vol.13 No.3
The probabilistic distributions of buckling strengths for compressive plates of normal and bridge high-performance steels were obtained through numerical analyses in order to develop a nominal design strength and a corresponding safety factor. In the numerical analyses, Monte Carlo simulation was used in combination with the response surface method to reduce the effort associated with the finite element analyses. For each value of the slenderness parameter R, a response surface of the normalized local bucking strength was determined based on the results of 114 finite element analyses using different residual stresses and initial defections. The response surface is approximated as a simple algebraic function of the residual stress and the initial deflection. Monte Carlo simulation is then carried out in order to evaluate the probabilistic distribution of the local bucking strength. The mean values obtained in the present study approach those of a mean curve proposed based on experiments. The standard deviation of the present study was approximately half that obtained based on experimental results in the range of 0.6<R<1.2.
A FANAROFF-RILEY TYPE I CANDIDATE IN NARROW-LINE SEYFERT 1 GALAXY Mrk 1239
Doi, Akihiro,Wajima, Kiyoaki,Hagiwara, Yoshiaki,Inoue, Makoto IOP Publishing 2015 ASTROPHYSICAL JOURNAL LETTERS - Vol.798 No.2
<P>We report finding kiloparsec-scale radio emissions aligned with parsec-scale jet structures in the narrow-line Seyfert 1 (NLS1) galaxy Mrk 1239 using the Very Large Array and the Very Long Baseline Array. Thus, this radio-quiet NLS1 has a jet-producing central engine driven by essentially the same mechanism as that of other radio-loud active galactic nuclei (AGNs). Most of the radio luminosity is concentrated within 100 parsecs and overall radio morphology looks edge-darkened; the estimated jet kinetic power is comparable to Fanaroff-Riley Type I radio galaxies. The conversion from accretion to jet power appears to be highly inefficient in this highly accreting low-mass black hole system compared with that in a low-luminosity AGN with similar radio power driven by a sub-Eddington, high-mass black hole. Thus, Mrk 1239 is a crucial probe to the unexplored parameter spaces of central engines for a jet formation.</P>
The East-Asian VLBI Network: Recent Progress and Results of the First Imaging Test Observation
Kiyoaki Wajima,Duk-Gyoo Roh,Se-Jin Oh,Taehyun Jung,Jongsoo Kim,Yoshiaki Hagiwara,Kazuhiro Hada,Noriyuki Kawaguchi,Hideyuki Kobayashi,Yuanwei Wu,Kenta Fujisawa,Tao An,Willem A. Baan,Wu Jiang,Zhi-Qiang 한국천문학회 2016 天文學會報 Vol.41 No.1