白井研究室の研究業績
2009年度(平成21年度)


白井研究室で行われた研究のうち，論文等の形で学術論文誌等に公表されたものを紹介します.
  1. 論文 等
    1. 2009. 9; Akio Kanezaki，Akimasa Hirata, Soichi Watanabe, H. Shirai； "Effects of dielectric permittivities on skin heating due to millimeter wave exposure," BioMedical Engineering Online http://www.biomedical-engineering-online.com/content/8/1/20
      [Abstract]: (Background) Because the possibility of millimeter wave (MMW) exposure has increased, public concern about the health issues due to electromagnetic radiation has also increased. While many studies have been conducted for MMW exposure, the effect of dielectric permittivities on skin heating in multilayer/heterogeneous human-body models have not been adequately investigated. This is partly due to the fact that a detailed investigation of skin heating in a multilayer model by computational methods is difficult since many parameters are involved. In the present study, therefore, theoretical analyses were conducted to investigate the relationship between dielectric permittivities and MMW-induced skin heating in a one-dimensional three-layer model (skin, fat, and muscle).
      (Methods) Approximate expressions were derived for the temperature elevation and temperature difference in the skin due to MMW exposure from analytical solutions for the temperature distribution. First, the power absorption distribution was approximated from the analytical solution for a one-layer model (skin only). Then, the analytical expression of the temperature in the three-layer model was simplified on the basis of the proposal in our previous study. By examining the approximate expressions, the dominant term influencing skin heating was clarified to identify the effects of the dielectric permittivities. Finally, the effects of dielectric permittivities were clarified by applying partial differentiation to the derived dominant term.
      (Results) Skin heating can be characterized by the parameters associated with the dielectric permittivities, independently of morphological and thermal parameters. With the derived expressions, it was first clarified that skin heating correlates with the total power absorbed in the skin rather than the specific absorption rate (SAR) at the skin surface or the incident power density. Using Debye-type expression we next investigated the effect of frequency dispersion on the complex relative permittivity of tissue. The parametric study on the total power absorbed in the skin showed that skin heating increases as the static permittivity and static conductivity decrease. In addition, the maximum temperature elevation on the body surface was approximately 1.6 times that of the minimum case. This difference is smaller than the difference caused by the thermal and morphological parameters reported in our previous study.
      (Conclusion) This paper analytically clarified the effects of dielectric permittivities on the thermally steady state temperature elevation and the temperature difference in the skin of a one-dimensional three-layer model due to MMW exposure.

  2. 国際会議発表 等
    1. 2009.5; R. Sato and H. Shirai, "Propagation Characteristics for a Simplified Indoor/Outdoor Interface Model," Proc. of 2009 Korea-Japan Joint Conference on AP/EMC/EMT, pp.263-266, Inchon, Korea.
    2. 2009.6; R. Sato and H. Shirai, "On Multiple Scattering Between Slits in an Infinite PEC Screen," Proc. of 2009 IEEE International Symposium on Antennas and Propagation and USNC/URSI National Radio Science Meeting, CDROM, Charleston, SC, USA.
    3. 2009.9; R. Sato and H. Shirai; "Efficient Ray-launching Analysis for Indoor Propagation Including Multiple Reflection Effect Inside Walls," Proc. of 2009 International Conference on Electromagnetics in Advanced Applications, CDROM, Turin, Italy.
    4. 2009. 10; M. Ishikawa and H. Shirai, "Non-contacting Estimation of Complex Permittivity Using RCS Measurement," Proc. of 2009 International Symposium on Antennas and Propagation (ISAP 2009), CDROM, Bangkok, Thailand.
  3. 学会, 研究会発表 等
    1. 2009. 11; 石川正行，白井宏, "後方散乱断面積を用いた誘電率の推定について，" 電気学会電磁界理論研究会，EMT-09-131, pp.45-50．
    2. 2009. 12; 萩原真央，北藪透, 石川博康, 白井宏, "非一様量子化器を用いたΔΣ変調器の量子化雑音低減に関する一検討，" 無線通信システム研究会, RCS-2009-197, pp.179-184.
    3. 2010. 3; 松田知紘，酒井泰三，渡辺聡一，和氣加奈子，白井宏, "ミリ波帯電波暴露実験時の温度上昇解析における１次元モデルの有効性，" 電子情報通信学会， 2010年総合大会，B-1-186，(CDROM)．
    4. 2010. 3; 萩原真央，北藪透, 石川博康，白井宏, "非一様量子化器を用いたΔΣ変調器の量子化雑音低減に関する検討，" 電子情報通信学会，2010年総合大会，B-5-76，(CDROM)．

  4. その他
    1. 2009.5； 白井 宏； 「米国でのPh.D.学位取得を通して学んだ国際コミュニケーション」， 電子情報通信学会 会誌 Vol.92, No.5, pp.386-389．