Browsing by Author "Chang, J.-Y."

Color structure descriptor (CSD) provides satisfactory image indexing and retrieval results among all color-based descriptors in MPEG-7. The superiority comes from the consideration of space distribution of colors. Hardware accelerator is a must because its good performance is at the expense of high computational complexity. In this paper, a design approach of speci c hardware accelerators for descriptors is explored. The characteristics of CSD algorithm are also analyzed and an ef cient architecture is proposed. The proposed architecture can generate CSD description of 256 256 image at 30 frames per second (fps). The architecture provides about 4.5 giga instructions per second (GIPS) to achieve real-time applications like assisting rate control in video coding system and circumstance change detection in surveillance system. © 2004 IEEE.

This article discusses the design of a digital library that addresses both content and knowledge management. The design of the digital library features two major distinctions: (1) the system incorporates a two-tier repository system to facilitate content management, and (2) the system incorporates an object-oriented model to facilitate the management of temporal information and exploits information extraction and deductive inference to derive implied knowledge based on the content of the digital library. The two-tier repository system relieves the system manager from manually maintaining the hyperlinks among the Web pages, when the digital library content is updated. The task of maintaining hyperlinks among Web pages can become cumbersome to the system manager if there are a large number of Web pages and hyperlinks. With respect to knowledge management, this design aims at facilitating temporal information management and deriving implied relations among the objects in the digital library. The motivation behind developing these knowledge processing utilities is to create a system that complements the capabilities of human beings. Deriving a comprehensive list of implied relations is an exhausting task if the digital library contains a great amount of information and the number of implied relations is great. With such knowledge-processing utilities, specialists are released from performing tedious work and can, therefore, spend more time with more productive philosophical activities to derive advanced knowledge. Applying knowledge management utilities effectively can extend the applications of digital libraries to new dimensions.

Wide band gap (WBG) semiconductors such as SiC and GaN devices are expected to replace Si power devices in the next generation power modules for renewable energy and smart grid to enhance their energy conversion efficiency through a characteristic of high frequency switching. However, the temperature of the WBG power module may reach 250°C as operating, which is much higher than the melting temperatures of the conventional solder materials like Sn37Pb (187°C), Sn3.0Ag0.5Cu (217°C) and Sn0.7Cu (227°C). Therefore, a new die attaching method is an urgent research subject for the assembly of WBG power modules. Sandia National Laboratories won the R&D 100 award in 2009 by the world's first full SiC module, in which the die attaching of SiC devices was accomplished by a transition liquid phase (TLP) method, 2 intermetallic phases including Ag3Sn and Ni3Sn4 were formed to bond SiC devices on a direct bond aluminum (DBA) and mount the DBA on a metal matrix composite baseplate, respectively, and the power module was capable to operate under a condition in excess of 400°C. Subsequently, Infineon announced a power chip embedded technology named BLADE for renewable energy applications in 2011, a same process so-called diffusion soldering was used to attach Si MOSFET device on an organic carrier by producing an intermetallic layer like Cu 6Sn5 between them. However, some disadvantages have been found in the previous cases. First, the bonding time is too long to achieve a high throughput production when the process temperature is lower than 300°C, whatever, the power ICs are easily damaged when the process temperature is as high as 350°C. Second, the intermetallic joint might degrade due to the voids induced by a volume contraction as heated. Third, there are some defects such as Kirkendall voids are formed at the interface between different intermetallics, which significantly impacts the reliability performance of the joint. A dual-phase solid-liquid interdiffusion bonding process was developed to solve the above-mentioned issues in this study. By the elemental design of the electrode compositions on both chip and substrate, a dual-phase intermetallic joint was formed to attach the chip on the substrate, and the bonding temperature was decreased to just 260°C. Furthermore, almost no void was found within the joint because they were rapidly stuffed by the formation of secondary intermetallic. The shear strength of the intermetallic joint was measured being higher than 20 MPa, even though experienced a temperature cycling test (Condition B, JESD22-A104), meaning that the new bonding technology was reliable and capable of manufacturing WBG power modules. © 2012 IEEE.

In the next-generation visual surveillance systems, content analysis tools will be integrated. In this paper, to accelerate these tools, it is proposed to integrate a hardware content analysis engine into a smart camera system-on-a-chip (SoC). A smart camera SoC hardware architecture with the proposed visual content analysis engine is first presented. This engine consists of dedicated accelerators and a programmable morphology coprocessor. Stream processing design concept, framelevel pipelining, and subword level parallelism are employed together to efficiently utilize the bandwidth of the system bus and achieve high throughput. The implementation results show that, with 168 K logic gates and 40.63 Kb on-chip memory, a processing speed of 30 640 × 480 frames/s can be achieved, while the operations of video object segmentation, object description and tracking, and face detection and scoring are supported. © 2009 IEEE.

By controlling the output coupling ratio, we demonstrate a novel wavelength-tunable L-band Erbium-doped fiber laser (EDFL) with a maximum tuning range up to 58 nm (from 1567 to 1625 nm) by controlling its output coupling ratio between 1% and 99%. The L-band EDFL is configured by using a bi-directionally dual-wavelength pumped EDFA in close-loop with an output coupler of tunable coupling ratio and an air-gap inserted FC/PC connector pair. Such an EDFL exhibits a quantum efficiency of 42% and an ultra-high power conversion efficiency of 37% under optimized pumping scheme, providing the small-signal gain and output power of ˜34 dB and 91 mW, respectively. Low variation of <1.2 dB on channel power, power fluctuation of 0.04% and a narrow linewidth of 0.03 nm are obtained. © 2006 Optical Society of America.