Browsing by Author "Hsu, Shih-Feng"

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A Key Caching Mechanism for Reducing WiMAX Authentication Cost in Handoff
(2009-10-01)
Hsu, Shih-Feng
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Lin, Yi-Bing
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資訊工程學系
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Department of Computer Science
The IEEE 802.1X is utilized in mobile Worldwide Interoperability for Microwave Access (WiMAX) authentication. This procedure incurs a long delay in WiMAX handoff. To resolve this issue, this paper proposes a key caching mechanism to eliminate the nonnecessary IEEE 802.1X authentication cost in WiMAX handoff. This mechanism is investigated through analytic and simulation modeling. Our study indicates that the key caching scheme can effectively speed up the handoff process.
Apparatus And Method For Executing The Handoff Process In Wireless Networks
(2009-07-02)
Lin, Yi-Bing
;
Hsu, Shih-Feng
Disclosed is an apparatus and method for executing the handoff process in the wireless networks. The apparatus comprises a processor to execute an identity checking mechanism. When a wireless network station wants to move from a source AP to a destination AP, the wireless network station sends an authentication request message to the destination AP. The identity checking mechanism searches a R0KH table of the destination AP for the R0KH ID contained in the authentication request message, and determines a setting parameter for executing a handoff process. Thereby, the wireless network station may execute the handoff process. A R0KH table of an AP consists of all IDs of R0KHs that can be accessed by the AP.
Highly efficient yellowish-white phosphorescent organic light-emitting devices
(2006-09-01)
Hsu, Shih-Feng
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Laskar, Inamur R.
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Chen, Teng-Ming
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Ma, Jie-Wei
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Hwang, Shiao-Wen
We have developed highly efficient yellowish-white organic light-emitting devices (WOLEDs) with very broad emission based on a orange emitter, (2-2 '-(4-flurophenyl)benzothiozolato-N,C-2 ') platinum (acetylacetonate) [Pt(F-bt)acac]. A yellowish-white light device with one of the highest electroluminescent (EL) efficiencies of 19.68cd/A (10.94%) with Commission Internationale d'Eclairage (CIE) coordinates of (x,y) = (0.399,0.453) has been demonstrated.
Selecting transition process for WLAN security
(2008-09-01)
Hsu, Shih-Feng
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Lin, Yi-Bing
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資訊工程學系
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Department of Computer Science
In wireless local area network (WLAN), a station (STA) accesses the Internet through an access point (AP), When switching from one AP to another, the STA executes the transition process, which may incur long delay and result in force-termination for real-time applications. The IEEE 802.11r proposes the fast basic service set (BSS) transition to speed up the transition process for a STA moving within the same mobility domain (MD). This scheme require unique MD assignment so that the STA knows whether it should conduct fast BSS transition process (for intra-MD scenario) or the expensive initial MD association process (for inter-MD scenario). However, how to guarantee unique MD identifier (MDID) assignment is not mentioned in the specification. This paper proposes a mechanism for IEEE 802.11r fast transition without using MDID, and therefore eliminates the cost for MDID management. Copyright (C) 2007 John Wiley & Sons, Ltd.
Three-wavelength white electrophosphorescence with two emissive materials
(2005)
Hsu, Shih-Feng
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Laskar, Inamur R.
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Chen, Teng-Ming
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Hwang, Shiao-Wen
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Chen, Chin H.
A New phosphorescent material based on Pt complex, Pt(btOMe)acac was synthesized and its specific EL emission spectrum from green to red combined with blue phosphorescent material. Firpic, can easily achieve high-efficiency three-wavelength white light with two emitters.
White light top-emitting light-emitting devices
(2005)
Hsu, Shih-Feng
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Hwang, Shiao-Wen
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Chen, Chin H.
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應用化學系
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Department of Applied Chemistry
Laminated cathode with high transparency and low reflectivity was modified form Ca/Ag and applied in White light top-emitting light-emitting devices (WTOLEDs). With modified cathode, a broad emission from white emitter is obtained which means strong optical interference is alleviated in the top-emitting devices.
White p-i-n organic light-emitting devices with high power efficiency and stable color
(2007-09-10)
Ho, Meng-Huan
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Hsu, Shih-Feng
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Ma, Jia-Wei
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Hwang, Shiao-Wen
;
Yeh, Pu-Cheng
Highly efficient p-i-n two-component white organic light-emitting devices have been fabricated with a thin dual emission layer system comprised of one codeposited emitting layer with blue and yellow dyes and one blue emitting layer, which gives rise to a balance white emission. The p-i-n white device achieved an electroluminescence efficiency of 10 cd/A and a power efficiency of 9.3 lm/W at 1000 cd/m(2) and a low voltage of 3.4 V with a Commission Internationale de l'Eclairage coordinates of (0.32, 0.43). The electroluminescent color of this p-i-n white organic light-emitting diode device has been shown to be immune to drive current density variations.