KINDAI UNIVERSITY


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OKINAKA Tomoo

Profile

FacultyDepartment of Civil and Environmental Engineering / Graduate School of Science and Engineering Research
PositionAssociate Professor
Degree
Commentator Guidehttps://www.kindai.ac.jp/meikan/297-okinaka-tomoo.html
URL
Mail
Last Updated :2020/04/03

Education and Career

Academic & Professional Experience

  •   2011 ,  - 2014 , Faculty of Science and Engineering, Kindai University

Research Activities

Research Areas

  • Social infrastructure (civil Engineering, architecture, disaster prevention), Structural and seismic engineering
  • Social infrastructure (civil Engineering, architecture, disaster prevention), Civil engineering (materials, implementation, construction management)
  • Social infrastructure (civil Engineering, architecture, disaster prevention), Hydroengineering

Research Interests

  • PIV, X-FEM, PDS-FEM

Misc

  • Application of the Image Analysis with Ultra-High-Speed Camera on the Crack Growth under Uniaxial Compresssion, OKINAKA Tomoo, Proceedings of the Japan Society for Photoelasticity, 14, 3, 182, 186,   2014 , 10.11395/jjsem.14.182, http://ci.nii.ac.jp/naid/130004691197
    Summary:Image analysis with ultra-high-speed camera is applied to the unstable crack growth under quasi-static uniaxial compression. Stress field around the moving crack tip in the transparent specimen is visualized by means of photo-elastic technique and images of growing cracks and the stress field are captured with the frame rate of 250,000 fps. As a result, it is revealed that wing cracks start initiation at each end of the initial defect with time lag, and the time difference in their initiation corresponds to the travelling time of the stress wave, which is released due to the growth of the primary crack, from one end of the initial defect to the other end.
  • Preliminary Evaluation and Prospective Evolution of a 16-Mfps Ultra-high Sensitivity CCD, ETOH Takeharu, Nguyen H. D, Dao V. T. S, TANAKA Masatoshi, TAKEHARA Kohsei, OKINAKA Tomoo, MARUYAMA Hirotaka, HAYASHIDA Tetsuya, ARAI Toshiki, KURETA Masatoshi, SEGAWA Mariko, ARAI Masatoshi, ITE Technical Report, 35, 17, 23, 26,   2011 03 15 , http://ci.nii.ac.jp/naid/110008594076
    Summary:In 2010, we developed a BSI image sensor capable of capturing images at 16Mfps. A preliminary evaluation result of the sensor is summarized. A concept of a next generation ultra-high-speed image sensor is also presented, which has a new function, image signal accumulation, in addition to the ultra-high-speed and the ultra-high-sensitivity.
  • Experimental and Numerical Study on Unstable Crack Growth under Quasi-Static Loading Condition, OKINAKA Tomoo, Transactions of the Japan Society of Mechanical Engineers. A, 75, 757, 1193, 1201,   2009 09 25 , 10.1299/kikaia.75.1193, http://ci.nii.ac.jp/naid/110007358714
    Summary:Unstable crack growth under quasi-static loading condition is studied both experimentally and numerically in this work. Image analysis is applied to the experimental study. Stress field around the propagating crack tip is visualized by means of photo-elastic technique, and images of the unstable crack growth and the visualized stress field around the propagating crack-tip are captured by the ultra-high-speed camera with the frame rate of 1000000fps. Images are successfully captured at every 0.3mm crack growth. Next, the numerical simulation technique to simulate the unstable crack growth without the rearrangment of nodes and elements is proposed. In the proposed technique, X-FEM is extended to include the dynamic phenomena. The result of the simulation is directly compared with the experimental observation. As a result of comparison, numerically simulated fringe patterns have a good agreenment with the experimentally observed ones, and hence, it is shown that the proposed algorithm has a sufficient accuracy.
  • EXPERIMENTAL AND NUMERICAL STUDIES ON THE CRACK GROWTH UNDER THE QUASI-STATIC LOADING, OKINAKA Tomoo, HORI Muneo, OGUNI Kenji, Journal of Japan Society of Civil Engineers, Ser. A1 (Structural Engineering & Earthquake Engineering (SE/EE)), 65, 2, 321, 334,   2009 , 10.2208/jsceja.65.321, http://ci.nii.ac.jp/naid/130004942767
    Summary:It is known that the crack path varies due to various disturbance factors, such as a heterogeneity of the material and interaction between cracks. Images of crack growth from parallel cracks under the quasistatic loading is captured by the ultra-high-speed camera, and the stress field around the propagating crack tip is visualized with the aid of dynamic photo-elastic technique in this work. First, the stability and the distribution pattern of crack path are discussed from the captured images. And then, the accuracy of the numerical quasi-static analysis of crack growth is studied through the comparison with the visualized stress field around the propagating crack tip.
  • Visualization of stress field around the propagating crack tip under the static loading with an ultra-high-speed camera, OKINAKA T, Journal of Applied Mechanics, JSCE, 10, 301, 309,   2007 , 10.2208/journalam.10.301, http://ci.nii.ac.jp/naid/40015713998
  • A Study on Post-Digital Processing for Convertible Triple-ISIS Camera, OKINAKA Tomoo, ETOH T. Goji, TAKEHARA Kohsei, KONDO Yasushi, MARUNO Hiromasa, SOYA Hideki, Transactions of the Visualization Society of Japan, 24, 1, 1, 8,   2004 07 31 , 10.3154/tvsj.24.1, http://ci.nii.ac.jp/naid/10013434940
    Summary:A post-digital processing for a convertible triple in-situ storage image sensor (ISIS) camera is developed in this work. The convertible Triple-ISIS camera is converted from three single ISIS cameras by users. The camera has the frame rate of 1Mfps, and is expected to be a powerful tool for scientific and engineering measurements, such as color imaging, imaging with different light wave bands, and so on. Position and sensitivity adjustments are required after conversion. Post-digital processing is employed for the adjustments instead of the mechanical ones, since the conversion is expected to be done by users. As the post-digital processing, an image of a test pattern for calibration is captured by the converted ISIS camera. The position and sensitivity are adjusted only from that image. Color imaging is employed as an example of applications. Images which are captured by three ISISes are adjusted by means of the proposed position and sensitivity adjustments, and are piled up. The accuracy of the adjustments are discussed through the resultant color pictures and movies captured at 125 Kfps.
  • :Application to the Crack Propagation Problem, OKINAKA Tomoo, ETOH T.Goji, Doboku Gakkai Ronbunshuu A, 6, 445, 454,   2003 , 10.2208/journalam.6.445, http://ci.nii.ac.jp/naid/130004091446
    Summary:The object of this research is to develop an accurate particle detection method for image analysis. Image analysis with in-situ storage image sensor (ISIS) camera is expected to be a powerful tool for finite deformation problem of continuum medium under high-strain rate. Accurate particle detection is of importance in this application, since the accuracy of detected strain strongly depends on that of particle detection. Tracking of Gaussian particle is combined with the size and configuration of photo diodes on ISIS. Then, the problem of particle detection is successfully reduced to the optimization problem with three variables. The proposed method results in the accuracy of 0.011 pixel according to the numerical simulation.<BR>Finally, the image analysis with proposed method is applied to the crack propagation problem under the impact loading. Strain concentration preceding the crack propagation is obtained through the image analysis.
  • An In-situ Storage Image Sensor of 1,000,000 fps with Slanted Linear CCD Storage, Etoh T.Goji, Mutoh Hideaki, Takehara Kohsei, Okinaka Tomoo, Takano Yasuhide, ITE Technical Report, 26, 26, 27, 33,   2002 03 18 , http://ci.nii.ac.jp/naid/110003671350
    Summary:An image sensor of 1,000,000 fps with image storage for consecutive 103 images is developed, which is called ISIS, In-situ Storage Image Sensor. Various innovative ideas support this achievement. Each pixel of the sensor has its own in-situ storage area of image signals during an image capturing phase, image signals generated in the photo-sensitive areas of all pixels are simultaneously recorded in the in-situ storage areas without being readout from the sensor, which realizes parallel recording at all pixels and, thus, image capturing at the ultimate high frame rate.
  • An In-situ Storage Image Sensor of 1,000,000 fps with Slanted Linear CCD Storage(Image Sensing Technology), Etoh Takeharu, Mutoh Hideki, Takehara Kohsei, Takano Yasuhide, Okinaka Tomoo, The journal of the Institute of Image Information and Television Engineers, 56, 3, 483, 486,   2002 03 01 , 10.3169/itej.56.483, http://ci.nii.ac.jp/naid/110003670880
    Summary:撮影速度100万枚/秒のビデオカメラ用撮像素子を開発した.撮影中は全画素並列で一斉に各画素の周辺に組入れられた記録領域に画像情報を蓄積するので究極の高速化が可能である.このような素子を画素周辺記録型撮像素子(ISIS: In-situ Storage Image Sensor)と呼ぶ.開発した素子の記録要素は少し斜めに置かれた通常の直線CCDで,非常に単純な構造である.ドレーンも組入れられており,103枚の連続上書き撮影が可能である.試験撮影により高感度,高画質であることも確かめられた.
  • Development of an Ultra-high-speed Video Camera, ETOH T. G, TAKEHARA K, TAKANO Y, OKINAKA T, KONDOH Y, MARUNO M, TAKUBO K, SOYA H, Journal of the Visualization Society of Japan, 21, 59, 62,   2001 07 01 , 10.3154/jvs.21.1Supplement_59, http://ci.nii.ac.jp/naid/10006385749
  • Development of an Ultra-high-speed Video Camera, Etoh T.G, Takehara K, Takano Y, Okinaka T, Kondoh Y, Maruno M, Takubo K, Soya H, Transactions of Visualization Society of Japan, 21, 1, 59, 62,   2001 , 10.3154/jvs.21.1Supplement_59, http://ci.nii.ac.jp/naid/130003649500
    Summary:An high speed video camera of 1, 000, 000 fps is under development. A series of test image sensors for the camera have been designed, fabricated and tested. The sensor is an ISIS, In-situ Storage Image Sensor, which stores image signals generated on each pixel in a storage area nearby to the pixel during an image capturing phase, and release them out of the sensor during a readout phase after the image capturing. The ISIS-VU was only to test the charge transfer rate to realize the target frame rate, 1, 000, 000 fps, and some optical characteristics; the ISIS-V1 was fabricated to check the basic performance and to actually capture continuous images of 16 frames at the frame rate; the ISIS-V2 is a prototype sensor, which is mounted on a mock-up camera under development; the ISIS-V3 under basic design will be the final target sensor of the project with high performance. The development process and performances achieved so far are briefly described.
  • A Study on the Brittle Fracture of Steel Bridge Structures during the Great Hanshin-Awaji Earthquake, Okinaka Tomoo, Journal of the Faculty of Science and Technology, Kinki University, 36, 69, 74,   2000 09 , http://ci.nii.ac.jp/naid/110000174003
  • A Study on the Material of the Brittle Fractured Bridge Pier Chitoshi MIKI, Hiroko KYUBA and Tomoo OKINAKA, OKURA Ichiro, MIKI Chitoshi, KYUBA Hiroko, OKINAKA Tomoo, Proceedings of the Japan Society of Civil Engineers, 640, 237, 238,   2000 , http://ci.nii.ac.jp/naid/130003801540
  • A Study on the Material of the Brittle Fractured Bridge Pier., MIKI Chitoshi, KYUBA Hiroko, OKINAKA Tomoo, Proceedings of the Japan Society of Civil Engineers, 612, 45, 53,   1999 01 21 , 10.2208/jscej.1999.612_45, http://ci.nii.ac.jp/naid/10002526853
    Summary:During the Great Hanishin-Awaji Earthquake, many steel bridge structures experienced brittle fractures, following the large scale deformation of their members. Hence, in this work, various material tests are performed on specimens which are made out of damaged steel bridge structures. The plastic strain, induced during the earthquake, is estimated through the change in their material properties. And then, the embrittleness of the steel due to the induced plastic strain is discussed, in order to study the mechanism of the occurrence of the brittle fracture during the earthquake.