Browsing by Author "Jeng, JH"

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An efficient architecture of ultrasonic scan conversion for implementing the cubic convolution interpolation
(1998)
Chang, DC
;
Wu, WR
;
Jeng, JH
;
電信工程研究所
;
Institute of Communications Engineering
The nearest neighbor and the bilinear interpolation methods are widely adopted to perform ultrasonic scan conversion in commercial ultrasound systems. The reason is that they are easy to implement and can satisfy real-time requirement. As the hardware technology advances in the recent decade, more complex yet more eligible interpolation methods can be realized. However, few articles in the literature concern details about the reconstruction of ultrasonic images. In this paper we propose an efficient architecture of ultrasonic scan conversion for implementing the cubic convolution interpolation. Some parameters needed to calculate in interpolation processes can be previously designed in ROMs (Read Only Memory) to improve computational efficiency. The system requirement analysis and computer simulations have shown the appealing feasibility in real-time practice and superior reconstruction quality to conventional interpolation methods.
An empirical approach toward realistic modeling of capital market volatility
(2005-01-01)
Wang, NJ
;
Wang, KL
;
Jeng, JH
;
交大名義發表
;
National Chiao Tung University
This paper examines the realized integrated variance of the daily return rate series of S&P 500, Nasdaq and FTSE 100 respectively. The realized integrated variance is defined to be the statistical variance of the market index return rates within a certain time window. In stead of regarding the realized integrated variance as an empirical approximate of the latent spot volatility as formally defined in a mathematical framework, such as GARCH, we treat it as a direct "observable" volatility measure and try to model its dynamics straightforward. First, we find the volatility series is a stochastic jump-decay process rather than being all-over-the-time stationary in each market. Also, under switching bull and bear market conditions, the volatility series exhibits significantly different dynamic characteristics. Secondly, some major market structures, related to volatility mechanism, might have changed due to the hefty usage of options for hedging volatility risk after 1997.
Application of A1/PI composite bumps to COG bonding process
(2001-06-01)
Jeng, JH
;
Hsieh, TE
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材料科學與工程學系
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Department of Materials Science and Engineering
This work demonstrates the probing, testability and applicability of Al/PI (aluminum/polyimide) composite bumps to the chip-on-glass (COG) bonding process for liquid crystal display (LCD) driver chip packaging. The experimental results showed that the thickness of Al overlayer on PI core of the bump, the location of pin contact, and the bump configuration affect bump probing testability. The bump with type IV configuration prepared in this work exhibited excellent probing testability when its Al overlayer thickness exceeded 0.8 mum. We further employed Taguchi method to identify the optimum COG bonding parameters for the Al/PI composite bump. The four bonding parameters, bonding temperature, bonding time, bonding pressure and thickness of Al overlayer are identified as 180 degreesC, 10 s, 800 kgf/cm(2) and 1.4 mum, respectively. The optimum bonding condition was applied to subsequent COG bonding experiments on glass substrates containing Al pads or indium tin oxide (ITO) pads. From the results of resistance measurement along with a series of reliability tests, Al pad is found to be good substrate bonding pad for Al/PI bump to COG process. Excellent contact quality was observed when the bumps had Al overlayer thickness over 1.1 mum. As to the COG specimens with substrate containing ITO pads, high joint resistance suggested that further contact quality refinement is necessary to realize their application to COG process.