觀察特定技術的發展歷程，可塑形其發展的技術軌跡，而觀察軌跡上的重要技術，更可瞭解技術發展與擴散的現象。近年來，各國為促進永續發展、落實節能減碳，積極地進行綠色能源的研究。本研究因而選定探討燃料電池中的膜電極組 (Membrane Electrode Assembly, MEA) 技術，透過膜電極組的專利引證網路、主路徑分析與迴歸分析，瞭解膜電極組技術的演進與擴散的情形。
　　本研究檢索美國專利資料庫 (USPTO) 1976年至2012年間燃料電池5層膜電極組 (5-layer MEA) 的專利資料共有1356筆專利，藉由引用關係建立出專利引證網路，並經由主路徑分析尋找出重要專利，繪出主要路徑發展圖，藉此可瞭解過去的研發歷程。此外，本研究亦蒐集專利引證網路中的資料，建立起研發單位間的引證網路，希望藉由專利資料瞭解知識流動與研發單位技術地位之間的關係。
　　透過主路徑分析燃料電池的專利引證網路，發現燃料電池的發展可分為三個階段：（一）配置膜電極組與質子交換膜的改良（二）催化電極的改良（三）
改善總反應表面積。對於研發單位而言，越早開始研究的研究機構，往往其技術地位也較高。與其他研發單位有越多連繫時，通常技術地位較好。最後，對於產業界的研發單位，技術的創新往往來自於產業內部的交流，而對其他性質的研發單位，則多需與產業界合作，此結果顯示膜電極組技術創新的原動力主要來自於產業界的研發。

Technological trajectory tends to explain the development process of technology. Based on the analysis of prominent technology on the trajectories, we can further explore the phenomena of technology evolution and knowledge diffusion. Nowadays, to reach the goal of sustainable development, many countries started to pay attentions on green energy, or advanced technology, for energy saving and emission reduction. Concerning the increasing trend toward a green world, this study focuses on discussing the technology of Membrane Electrode Assembly (MEA) used in fuel cell. By the investigation of patent citation network, path analysis and regression analysis, further explore how the knowledge of this technologies evolve and diffuse across different locations.
The dataset of this study focuses on the technologies (patents) in 5-layer MEA used in fuel cells from US Patent and Trademark Office (USPTO), in a total number of 1356 patents. A patent citation network is built based on citation relationships, and some prominent ones with higher citation are recognized with path analysis. The result is shown in development path diagram, by which the research paths of industry are discussed. Additionally, the study established the network between R & D units by the information of patent, hoping to understand the relationship between technological position and the flow of knowledge.
By the mainpath analysis of patent citation network of fuel cell, we found the development of fuel cell can be divided into three stages: (1) disposition of the membrane electrode and improvement of the proton exchange membrane, (2) improvement of thecatalyst electrode, (3) improvement in the total reaction surface area. Additionally, for R & D unit, the senior institutes or which linked with the others often have the stronger technological positions. Finally, for the industry's R & D units, technological innovation often comes from the exchange within the industry, and on other properties of R & D units, the more need to collaborate with industry, this result shows the driving force of membrane electrode assembly technological innovation comes from the industry.

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