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博碩士論文 etd-0726102-002528 詳細資訊
Title page for etd-0726102-002528
論文名稱
Title
行動通訊電話在人體頭部內所造成的SAR分佈及溫度提升
SAR Distribution and Temperature Increase in the Human Head for Mobile Communication
系所名稱
Department
畢業學年期
Year, semester
語文別
Language
學位類別
Degree
頁數
Number of pages
53
研究生
Author
指導教授
Advisor
召集委員
Convenor
口試委員
Advisory Committee
口試日期
Date of Exam
2002-07-15
繳交日期
Date of Submission
2002-07-26
關鍵字
Keywords
時域有限差分、特定吸收率、熱傳導方程式
SAR, Bioheat Equation, FDTD
統計
Statistics
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The thesis/dissertation has been browsed 5685 times, has been downloaded 5850 times.
中文摘要
近年來無線通訊的發展迅速,無線通訊設備的普遍使用,造成人體暴露於無線通訊系統所發射的大量無線電波的環境中。生活在這種大量電磁輻射的影響下,人體健康可能遭受的危害也愈來愈受到重視。無線通訊所涵蓋的領域中,又以 GSM行動通訊系統是目前在國內最廣被使用的系統,行動通訊的使用者在使用手機時,由於使用者非常接近輻射天線,大部分的輻射功率會散佈經過人體,而被人體的局部區域吸收,為了確保手機的安全使用,必須對手機天線的輻射場在人體內的分布有詳細的了解。

目前已知的多種電磁波可能造成的生物效應中,以加熱效應最為顯著且其影響也最明確,目前多數的國家在手機公開販售前,都要求必須進行SAR值的量測。SAR值的量測必須使用貴重的儀器,而且雖然測量時所用的假人頭(phantom)是依照標準調製組織液,但是就學理上而言,假人頭的細部結構仍然是和真實的人體頭部有相當大的差別。因此從理論上去探究手機天線的輻射波在人體頭部範圍的SAR值分佈,就顯得有其必要性。人體全身的組織對電磁波的傳遞而言,是一種非均勻的有損耗性介質材料,這一類的電磁傳播問題最適合應用時域有限差分(FDTD)法分析處理。

本論文的目的即在於建立可應用於FDTD法的人體實際模型,模擬分析1/4波長單極天線手機輻射時在人體頭部所造成的SAR分佈,然後應用熱傳導方程式(bioheat equation),將SAR值轉換成溫度變化。

Abstract
Rapid development of wireless communications has led to the excessive use of wireless equipments. The purpose of communication is achieved through the transmission and reception of electromagnetic waves by the wireless equipments. Living in the environment of massive electromagnetic exposure coming from these wireless equipments, the health issue is a growing concern among the people who use the equipments and also the general public. The GSM communication system is the most widely used segment of wireless communications currently in Taiwan. The user of the mobile terminal (handset) is in close proximity to the radiating antenna. Most of the EM radiation emitting from the antenna will pass through the body of the user and be absorbed by the human tissue. It is therefore important to consider possible health hazards due to this type of EM exposure.

Among all the possible biological effects caused by EM exposure, the heating effect is the most significant and its influence on biological tissues is proven. Currently most countries require the handsets to be tested for SAR values before the handsets are ready for purchasing on the markets. SAR tests require the utilization of expensive measurement facilities. Moreover, even though the phantom used for SAR measurement is prepared according to standards, theoretically the phantom is still not identical to the anatomical constituents of the human head. Henceforth, it is necessary to investigate the field distribution inside the human head, using an anatomical model, due to the exposure of radiation coming from the handset antennas from the theoretical point of view. The whole human body is an inhomogeneous lossy dielectrics as far as EM wave propagation is concerned. This feature renders the problem easy to tackle using the FDTD numerical method.

This thesis presents a method to build up a numerical human head model suitable for the FDTD analysis using data set from the “visible human” project readily available from the internet. The thesis then investigates the field distribution inside the human head, under the exposure of the quarter-wavelength monopole antenna on a dielectric covered metal box. Temperature increases due to the absorption of EM energy by the human head will then be deducted from the bioheat equation.

目次 Table of Contents
謝辭…………………………………………………………………………………..Ⅰ
論文提要……………………………………………………………………………..Ⅱ
目錄…………………………………………………………………………………..Ⅴ
圖表目錄……………………………………………………………………………..Ⅶ
第一章 序論…………………………………………………………………………..1
1.1 研究背景及目的…………………………………………………………….1
1.2 論文大綱…………………………………………………………………….3
第二章 FDTD演算法………………………………………………………………...4
2.1 FDTD公式推導……………………………………………………………...4
2.2 Courant穩定準則…………………………………………………………….9
2.3 激發源……………………………………………………………………...10
第三章 吸收邊界條件………………………………………………………………11
3.1 Mur吸收邊界……………………………………………………………….12
3.2 Berenger的PML吸收邊界…………………………………………………12
3.2.1 定義PML介質……………………………………………………...14
3.2.2 PML介質內平面波的傳播…………………………………………15
3.2.3 最佳化參數…………………………………………………………16
第四章 導線近似公式………………………………………………………………19
第五章 人體頭部SAR分佈及溫度提升…………………………………………...24
5.1 人頭模型…………………………………………………………………...24
5.2 特定吸收率(SAR)…………………………………………………………26
5.2.1 SAR的計算………………………………………………………….26
5.2.2 線性定理……………………………………………………………27
5.3 熱傳導方程式(bioheat equation)…………………………………………..28
5.3.1人體組織內的溫度計算…………………………………………….28
5.3.2穩定準則…………………………………………………………….29
5.3.3邊界上的溫度計算………………………………………………….30
5.3.4人體組織初始溫度的計算………………………………………….32
5.4 模擬二維結構的肌肉組織………………………………………………...32
5.5 1/4λ單極天線的手機……………………………………………………...34
5.5.1 人頭模型內SAR分佈……………………………………………...38
5.5.2 人頭模型內溫度上升的變化………………………………………42
第六章 結論…………………………………………………………………………47
參考文獻……………………………………………………………………………..48
附錄A Berenger的完美匹配層非均勻網格差分方程式…………………………..51
參考文獻 References
參考文獻

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