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BBISS(Broad Band Internet Service via Satellite)Ka-band Broadband Satellite Plan
Tatsukawa, Kenichi,Akinaga, Wakoto,Yamada, Kenichi,Hashimoto, Katsumasa,Okui, Tamio,Koishi, Yoichi,Horiuch, Yasuo 통신위성우주산업연구회 2004 Joint Conference on Satellite Communications Vol.2004 No.-
Broadband internet, by ADSL, fiber optic, and CATV circuit has become very popular. However this service can not be shared in the depopulated area, where Broadband service business is difficult to materialize. BBISS satellite has been planned to provide the Broadband service to these un-equipped areas. In order to do so, a wide Ka frequency band is utilized and moreover, multi-beam antenna is adopted to realize the improvement of the efficient frequency reuse and to succeed in earth station antenna miniaturization. As for the problematic matter in use of the Ka-band due to great rainfall attenuation will be solved by use of adaptive code modulation method and realize high availability, and high=speed information speed will be provided in case of fine weather by maintaining the necessary minimum margin. This paper introduces best effort service by BBISS with such features.
Kenichi Ohura,Akitake Makinouchi,Cristian Teodosiu,Yutaka Nagai,Jyuichi Nagse 한국소성가공학회 2010 기타자료 Vol.2010 No.6
The warpage of casting parts is a critical issue, especially for large industrial products. Besides, it is difficult to predict the warpage accurately in the casting process because of its complex dependence on mechanical and thermal factors such as the constitutive law of the high temperature metal, the temperature history of the entire part and the restrictions imposed on the deformation by the mold wall. In the present paper, a 3D finite element software V-Shrink developed within the VCAD System Research Program is used to simulate the warpage of an L-plate sand mold casting. It takes into account the thermal coupling between the cast and the mold with non-uniform heat transfer coefficient depending on the local air-gap thickness. 1) The thermo-elastoplastic constitutive law with the temperature dependency of the yield stress is used for the thermal contraction analysis. 2) The simulated warpage of the L-plate casting is in good agreement with the experimental data obtained by a 3D digitizer. Furthermore, the well-known technical finding that the inelastic strain caused by the temperature dependence of the yield stress and the local delay of the temperature drop is a dominant factor of the warpage, is confirmed by the simulation.
Development of Omnidirectional Electric Wheelchair with Zabuton Sensor
Kenichi Iida,Hisao Yoshikawa,Taichi Mori,Toshio Hira 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
In this paper, we propose an Omnidirectional Electric Wheelchair (OEW). The proposed OEW has four omniwheels for the omnidirectional movement. Two of the omniwheels are arranged to X-axis direction and the other two are arranged to Y-axis direction. By controlling the movement of the omniwheels, the OEW can instantaneously rotate and move in all directions. Hence that, especially in the narrow spaced indoor environment, the omnidirectional nature of the OEW has an advantage over the standard wheelchair. Furthermore, the operator’ posture is used as signal to the OEW. The operator’ posture is measured by a “abuton sensor”which uses a pressure sensor to measure the pressure distribution. The effectiveness of proposed the system is reflected by the experimental results of the prototype OEW and Zabuton sensor system.
A Perspective of Reconfigurable RF Circuits
Kenichi Okada,Akira Matsuzawa 에스케이텔레콤 (주) 2010 Telecommunications Review Vol.20 No.5
Electronic devices have become mature and been diversified, and flexibility is becoming increasingly important in integrated circuits. Circuits have obtained flexibility and reconfigurability at various levels due to digitization, i.e. simplification, but real-world interfaces such as external communications and sensors intrinsically require analog circuits rather than digital. Digital signals can be processed by PCs, DSPs, FPGAs, custom LSIs, and other digital circuits. In analog circuits, however, general-purpose products offer only a limited and fixed range of functions. The development of reconfigurable analog RF circuits will provide a means of breaking through this impasse and realize both flexibility and high performance. Here we provide a forward-looking perspective on reconfigurable analog RF circuit technology; in particular it s present and future key components, and describes the pathway for innovation and change.
Kenichi Yamane,Satoshi Nakaba,Masahiro Yamaguchi,Katsushi Kuroda,Yuzou Sano,I. Wuled Lenggoro,Takeshi Izuta,Ryo Funada 한국대기환경학회 2012 Asian Journal of Atmospheric Environment (AJAE) Vol.6 No.4
To understand the effect of aerosols on the growth and physiological conditions of trees in forests, it is important to know the state of aerosols that are deposited on the surface of the leaves or needles. In this study, we developed methods of visualization of submicron-sized aerosols that were artificially deposited from the gas-phase or liquid phase onto tree leaves or needles in trees. Firstly, we used field-emission scanning electron microscopy (FE-SEM) to observe black carbon (BC) particles that were artificially sprayed onto the leaves or needles. The distribution of BC particles deposited on the leaves and needles were distinguished based on the size and morphological features of the particles. The distribution and agglomerates size of BC particles differed between two spraying methods of BC particles employed. Secondly,we tried to visualize gold (Au) particles that were artificially sprayed onto the leaves using energy dispersive X-ray spectrometry (EDX) coupled to FE-SEM. We detected the Au particles based on the characteristic X-ray spectrum, which was secondarily generated from the Au particles. In contrast to the case of BC particles, the Au particles did not form agglomerates and were uniformly distributed on the leaf surfaces. The present results show that our methods provide useful information of adsorption and/or behavior of fine particles at the submicron level on the surface of the leaves. To understand the effect of aerosols on the growth and physiological conditions of trees in forests, it is important to know the state of aerosols that are deposited on the surface of the leaves or needles. In this study, we developed methods of visualization of submicron-sized aerosols that were artificially deposited from the gas-phase or liquid phase onto tree leaves or needles in trees. Firstly, we used field-emission scanning electron microscopy (FE-SEM) to observe black carbon (BC) particles that were artificially sprayed onto the leaves or needles. The distribution of BC particles deposited on the leaves and needles were distinguished based on the size and morphological features of the particles. The distribution and agglomerates size of BC particles differed between two spraying methods of BC particles employed. Secondly,we tried to visualize gold (Au) particles that were artificially sprayed onto the leaves using energy dispersive X-ray spectrometry (EDX) coupled to FE-SEM. We detected the Au particles based on the characteristic X-ray spectrum, which was secondarily generated from the Au particles. In contrast to the case of BC particles, the Au particles did not form agglomerates and were uniformly distributed on the leaf surfaces. The present results show that our methods provide useful information of adsorption and/or behavior of fine particles at the submicron level on the surface of the leaves.
Kenichi Kawada,Tohru Suzuki 한국원자력학회 2021 Nuclear Engineering and Technology Vol.53 No.12
To improve the capability of the SAS4A code, which simulates the initiating phase of core disruptiveaccidents for MOX-fueled Sodium-cooled Fast Reactors (SFRs), the authors have investigated in detail thephysical phenomena under unprotected loss-of-flow (ULOF) conditions in a previous paper (Kawada andSuzuki, 2020) [1]. As the conclusion of the last article, fuel stub motion, in which the residual fuel pelletswould move toward the core central region after fuel pin disruption, was identified as one of the keyphenomena to be appropriately simulated for the initiating phase of ULOF. In the present paper, based on the analysis of the experimental data, the behaviors related to the stubmotion were evaluated and quantified by the author from scratch. A simple model describing fuel stubmotion, which was not modeled in the previous SAS4A code, was newly proposed. The applicability ofthe proposed model was validated through a series of analyses for the CABRI experiments, by which thestub motion would be represented with reasonable conservativeness for the reactivity evaluation ofdisrupted core
Bearing Only Localization for Multiple AUV with Acoustic Broadcast Communication
Kenichi Fujita,Takumi Matsuda,Toshihiro Maki 제어로봇시스템학회 2019 제어로봇시스템학회 국제학술대회 논문집 Vol.2019 No.10
This paper presents the method and characteristic of bearing only localization applying for multiple low-cost autonomous underwater vehicles (AUVs). In the proposed method, each AUV equips sensors which are not always accurate enough to estimate position. The method estimates the positions of the AUVs combining the information of the directions from the AUVs to the acoustic source and sensor values on the AUVs. This paper analyzed the capability of this method using the mathematical model of the system with observability rank condition. The result indicates the system has observability as far as the AUV does not move directly from or to the acoustic source. The position of the AUVs was also estimated using the particle filter. The method succeeded in the particles from diverging. We also observed that the accuracy of the estimation depends on the relative position of the acoustic source from the AUV.