Jao-Hwa Kuang

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High-power light-emitting diode (LED) modules encapsulated with different lens shapes after a thermal-aging test were studied experimentally and numerically. Samples from different manufacturers were aged at 80degC, 100degC, and 120degC under a constant driving voltage of 3.2 V. The results showed that the LED modules encapsulated with a(More)
Decay of radiation pattern and optical spectrum of high-power LED modules fabricated by different manufacturers after a thermal-aging test were investigated experimentally and numerically. Samples were aged at 65degC, 85degC, and 95degC under a constant current of 350 mA. The results showed that the radiation pattern of the LED modules at the two view(More)
A varying-frequency control Flyback rectifier for LED driving in Boundary-Conduction Mode (BCM) is presented. Comparing with Discontinuous-Conduction Mode, BCM has the advantages like smaller coupling inductor current, less current stress for circuit component, slight output current ripple, and higher power factor performance. For lower output application(More)
The thermally induced fiber alignment shifts of fiber-solder-ferrule (FSF) joints in laser module packaging have been studied experimentally and numerically. From direct measurements of the metallographic photos with and without temperature cycling, fiber displacement shifts of up to a 0.8 /spl mu/m were found after undergoing 500 temperature cycles.(More)
We explore the dependence of power losses on average plastic energy densities as rays propagate along deformed polymer optical fibers (POFs). The variation of power losses in deformed POFs with different bend radii and elongations are measured and analyzed. Three-dimensional elastic-plastic finite-element models are used to calculate average plastic energy(More)
In this study, a high sensitivity and easy fabricated plastic optical fiber (POF) displacement sensor is proposed. A POF specimen subjected to dual cyclic bending is used to improve the sensitivity of the POF displacement sensor. The effects of interval between rollers, relative displacement and number of rollers on the sensitivity of the displacement(More)
A novel measurement technique employing an ultra high precision laser displacement meter (LDM) with a 20 nm resolution for probing the post-weld-shift (PWS) induced fiber alignment shifts in laser-welded laser module packaging is presented. The results show that the direction and magnitude of the fiber alignment shifts induced by PWS in laser-welded laser(More)
The postweld-shift (PWS) compensation techniques employing a laser displacement meter (LDM) in the transistor outline (TO)-Can-type laser-welded laser module package and a high-magnification camera with image capturing system (HMCICS) in the butterfly-type laser-welded laser module packages are quantitatively investigated and compared. The results show that(More)
A quantitative postweld shift (PWS) correction employing a notch-saddle-compensation technique (NSCT) in a laser-welded butterfly-type laser module package is presented. A predetermined notch geometry is proposed to guide the welding compensation in the specific direction and magnitude precisely. The results show that 82% to 99% of the relative coupling(More)