Browsing by Author "Hsu, CY"

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An efficient IP-Level power model for complex digital circuits
(2003)
Hsu, CY
;
Liu, CNJ
;
Jou, JY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper, we propose an efficient IP-Level power model with a small lookup table for complex CMOS circuits. The table has only one dimension that maps the zero-delay charging and discharging capacitance into the real power consumption of pattern pairs but still has high accuracy. In order to improve the efficiency of the characterization process, the Monte Carlo approach is used during the estimation of the average power to skip the samples that will not increase the accuracy too much. The experimental result shows the table sizes are only up to 107 entries for ISCAS'85 benchmark circuits and the estimation error is only 2.99% on average using the lookup table.
An efficient power model for IP-level complex designs
(2003-08-01)
Hsu, CY
;
Liu, CNJ
;
Jou, JY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper, we propose an efficient IP-Level power model with a small lookup table for complex CMOS circuits. The table has only one dimension that maps the zero-delay charging and discharging capacitance (CDC) into the real power consumption of pattern pairs but still has high accuracy. In order to reduce the table size, we collect those pattern pairs with similar CDC values to be a group and only set an entry in the lookup table for each group. The proposed dynamic grouping process can automatically increase the entries of the lookup tables to cover the current CDC distribution of designs during the power characterization process. In order to improve the efficiency of characterization process, the Monte Carlo approach is used during the estimation for the average power of each group to skip the samples that will not increase the accuracy too much. After the power model of a circuit is built, the average power consumption for any test sequence can be estimated easily. The experimental result shows that the table sizes are only up to 107 entries for ISCAS'85 benchmark circuits and the estimation error is only 2.99% on average using this lookup table.
Caspase activation of mammalian Sterile 20-like kinase 3 (Mst3) - Nuclear translocation and induction of apoptosis
(2002-09-13)
Huang, CYF
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Wu, YM
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Hsu, CY
;
Lee, WS
;
Lai, MD
Mammalian Sterile 20-like kinase 3 (Mst3), the physiological functions of which are unknown, is a member of the germinal center kinase-III family. It contains a conserved kinase domain at its NH2 terminus, whereas there is a regulatory domain at its COOH terminus. In this study we demonstrate that endogenous Mst3 is specifically cleaved when Jurkat cells were treated with anti-Fas antibody or staurosporine and that this cleavage is inhibited by the caspase inhibitor, Ac-DEVD-CHO. Using apoptotic Jurkat cell extracts and recombinant caspases, we mapped the caspase cleavage site, AETD(313), which is at the junction of the NH2-terminal kinase domain and the COOH-terminal regulatory domain. Caspase-mediated cleavage of. Mst3 activates its intrinsic kinase activity, suggesting that the COOH-terminal domain of Mst3 negatively regulates the kinase domain. Furthermore, proteolytic removal of the Mst3 COOH-terminal domain by caspases promotes nuclear translocation. Ectopic expression of either wild-type or COOH-terminal truncated Mst3 in cells results in DNA fragmentation and morphological changes characteristic of apoptosis. By contrast, no such changes were exhibited for catalytically inactive Mst3, implicating the involvement of Mst3 kinase activity for mediation of these effects. Collectively, these results support the notion that caspase-mediated proteolytic activation of Mst3 contributes to apoptosis.
Decision feedback IBI mitigation in OFDM systems
(2005)
Wu, WR
;
Hsu, CY
;
電信工程研究所
;
Institute of Communications Engineering
When the channel response is longer than the guard interval in OFDM systems, inter-block interference (1131) will occur and the desired circular convolution property (the transmit symbol and the channel response) will not hold. These problems can seriously degrade the performance of OFDM systems. In this paper, we combine the decision feedback and cyclic reconstruction techniques with an iterated channel estimate method to remedy these problems. We consider pilot-tone based OFDM systems operating in fading channel environments. We derived a least-squares (LS) channel estimation and the optimal frequency domain equalizer (FEQ). Since the computational complexity of the optimal FEQ is high, we then use a simple suboptimal one. Incorporating with decision feedback and cyclic reconstruction, we obtain an iterated IBI mitigation method. Simulations based on a modified DVB-T specification demonstrate that the proposed method can effectively reduce the 1131 and enhance the overall system performance.
Effect of thermal annealing of Ni/Au ohmic contact on the leakage current of GaN based light emitting diodes
(2003-09-22)
Hsu, CY
;
Lan, WH
;
Wu, YS
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材料科學與工程學系
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Department of Materials Science and Engineering
The effect of thermal annealing on current-voltage properties of GaN light emitting diodes (LEDs) has been studied. At annealing temperatures above 700 degreesC, the p-n junction of the diodes became very leaky and Ga-contained metallic bubbles were observed on the surface of Ni/Au p-ohmic contact. Transmission electron microscopy and energy dispersive x-ray spectrometer studies revealed that these metallic bubbles resided directly on top of the threading dislocations in GaN and both Ni and Au were indiffused into the LED structure along the cores of the TDs. The conducting paths formed by the metal containing dislocation cores are believed to be the cause for the observed short circuit behavior of p-n junctions at high annealing temperatures. (C) 2003 American Institute of Physics.
Efficient vector compaction methods for power estimation with consecutive sampling techniques
(2004-11-01)
Hsu, CY
;
Liu, CNJ
;
Jou, JY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
For large circuits, vector compaction techniques could provide a faster solution for power estimation with reasonable accuracy. Because traditional sampling approach will incur useless transitions between every sampled pattern pairs after they are concatenated into a single sequence for simulation, we proposed a vector compaction method with grouping and single-sequence consecutive sampling technique to solve this problem. However, it is very possible that we cannot find a perfect consecutive sequence without any undesired transitions. In such cases, the compaction ratio of the sequence length may not be improved too much. In this paper, we propose an efficient approach to relax the limitation a little bit such that multiple consecutive sequences are allowed. We also propose an algorithm to reduce the number of sequences instead of setting the number as one to find better solutions for vector compaction problem. As demonstrated in the experimental results, the average compaction ratio and speedup can be significantly improved by using this new approach.
GaN-based light-emitting diodes with Ni/AuBe transparent conductive layer
(2003-10-01)
Chen, LC
;
Hsu, CY
;
Lan, WH
;
Teng, SY
;
材料科學與工程學系
Ni/AuBe as p-type ohmic contact to p-GaN in the heat treatment process are reported. By selection of an optimum condition, the best construction of Ni/AuBe bi-layers is 5 nm/5 nm thick. The light-transmission is about 75% for 470 nm blue light and the lowest specific contact resistance obtained is 2 x 10(-3) Omega cm(2) examined by transmission line model after heat treatment process at 500 degreesC alloying temperature during 10 min in nitrogen ambient. The Be atom may plays an important role in the formation of good ohmic contacts. On the other hand, Ni/AuBe bi-layers are also applied to GaN-based light-emitting diodes (LEDs) as p-type ohmic contact electrode. The typical I-V characteristics of the GaN-based LEDs with 5 nm/5 nm-thick Ni/AuBe TCL exhibit a forward-bias voltage of 3.41 V at injection Current of 20 mA. (C) 2003 Elsevier Ltd. All rights reserved.
Identification and characterization of the nuclear import and export signals of the mammalian Ste20-like protein kinase 3
(2004-08-13)
Lee, WS
;
Hsu, CY
;
Wang, PL
;
Huang, CYF
;
Chang, CH
Mst3, a human Ste20-like protein kinase, has been recently demonstrated to undergo a caspase-mediated cleavage during apoptosis. The proteolytic cleavage of the C-terminus of Mst3 caused nuclear translocation of its kinase domain. This work provides evidence that Mst3 may contain a bipartite-like nuclear localization sequence (NLS) at the C-terminus of its kinase domain (residues 278-292). The removal of NLS from the kinase domain of Mst3 led to the cytoplasmic accumulation of EGFP-Mst3 (Delta277). The presence of nuclear exporting signals in the Mst3 was also demonstrated by leptomycin B-treatment and serial deletion of the C-terminal regulatory domain of Mst3. A nuclear export signal was also postulated to be in the regions of amino acids 335-386. In conclusion, Mst3 contains both NLS and NES signals, which may cooperate to control the subcellular distribution of Mst3. (C) 2004 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
Improved vector compaction for power estimation with multi-sequence sampling technique
(2003)
Hsu, CY
;
Liu, CNJ
;
Jou, JY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A fast and accurate power estimation of circuits is definitely required when the low power issues become more and more important. For large circuits, vector compaction techniques could provide a fast solution for power estimation with reasonable accuracy. In previous work [11], we proposed an efficient vector compaction method with grouping and single-sequence consecutive sampling technique for CMOS circuits. The single-sequence approach improved the losses on compaction ratio and speedup by minimizing the useless transitions in traditional random or random-liked sampling approaches but it still involved some undesired transitions. In this paper, we propose a new consecutive sampling technique. multi-sequence approach. It can dramatically reduce the useless transitions without involving any undesired transitions. Compared to the random sampling and the single-sequence approaches, the experimental results demonstrate that the average compaction ratio and the average speedup can be significantly improved with our multi-sequence approach.
Infrared microscopy of hot spots induced by Joule heating in flip-chip SnAg solder joints under accelerated electromigration
(2006-01-09)
Chiu, SH
;
Shao, TL
;
Chen, C
;
Yao, DJ
;
Hsu, CY
Joule heating effect in solder joints was investigated using thermal infrared microscopy and modeling in this study. With the increase of applied current, the temperature increased rapidly due to Joule heating. Furthermore, modeling results indicated that a hot spot existed in the solder near the entrance point of the Al trace, and it became more pronounced as the applied current increased. The temperature difference between the hot spot and the solder was as large as 9.4 degrees C when the solder joint was powered by 0.8 A. This hot spot may play an important role in the initial void formation during electromigration.
ISI mitigation and channel tracking in MIMO-OFDM systems
(2005)
Wu, WR
;
Hsu, CY
;
Hsu, HT
;
電信工程研究所
;
Institute of Communications Engineering
When the channel response is longer than the guard interval in OFDM systems, inter-symbol interference (ISI) and intercarrier interference (ICI) will occur and this may seriously affect the receiver performance. In this paper, we consider the ISI and ICI mitigation in MIMO-OFDM systems. We propose to use a decision feedback technique for ISI cancelation and a cyclic reconstruction technique for ICT removal. Combining with the V-BLAST method, we obtain an iterative signal detection algorithm for MIMO-OFDM systems. Since the channel may be time-vaniant, we then further propose an adaptive time-domain channel tracking method. The algorithm can be implemented with IFFT so that its computational complexity is low. Simulations demonstrate that the proposed method can effectively enhance the overall MIMO-OFDM system performance.
Project-based knowledge maps: combining project mining and XML-enabled topic maps
(2004)
Liu, DR
;
Hsu, CY
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資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
Many enterprises implement various business projects on the Internet in the global knowledge economy. The task of managing distributed and heterogeneous project knowledge is very important in increasing the knowledge assets of enterprises. Accordingly, this work presents a project-based knowledge map system to properly organize project knowledge into topic maps, from which users can obtain in-depth concepts to facilitate further project development. A two-phase data mining approach involving the ISO/ISEC 13250 topic maps and Extensible Markup Language (XML) is used to establish the proposed system, which can determine knowledge patterns from previous projects and transform these patterns into a navigable knowledge map. The map can help users to locate required information and also offers subject-related information easily and rapidly over the Internet.
Temperature and current-density distributions in flip-chip solder joints with Cu traces
(2006-05-01)
Hsu, CY
;
Yao, DJ
;
Liang, SW
;
Chen, C
;
Yeh, ECC
Three-dimensional simulation was performed to investigate the temperature and current density distribution in flip-chip solder joints with Cu traces during current stressing. It was found that the Cu traces can reduce the Joule heating effect significantly at high stressing currents. When the solder joints were stressed by 0.6 A, the average temperature increase in solder bumps with the Al traces was 26.7 degrees C, and it was deceased to 18.7 degrees C for the solder joint with the Cu traces. Hot spots exist in the solder near the entrance points of the Al or Cu traces. The temperature increases in the hot spot were 29.3 degrees C and 20.6 degrees C, for solder joints with the Al traces and Cu traces, respectively. As for current density distribution, the maximum current density inside the solder decreased slightly from 1.66 X 10(5) A/cm(2) to 1.46 X 10(5) A/cm(2) when the Al traces were replaced by the Cu traces. The solder joints with the Cu traces exhibited lower Joule heating and current crowding effects than those with the Al traces, which was mainly attributed to the lower electrical conductivity of the Cu traces. Therefore, the solder joints with the Cu traces are expected to have better electromigration resistance.
The influences of contact interfaces between the indium tin oxide-based contact layer and GaN-based LEDs
(2006)
Hsu, CY
;
Lan, WH
;
Wu, YCS
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材料科學與工程學系
;
Department of Materials Science and Engineering
We have fabricated GaN-based light-emitting diodes (LEDs) using transparent indium tin oxide-based (ITO-based) p contacts. The current-voltage characteristics and life tests of GaN-based LEDs have been studied. LED life tests showed that a pure ITO contact layer had poor reliability at high current stress. We also found that the GaN-based LED could achieve good reliability with a NiO/ITO contact layer. Using transmission electron microscopy and energy-dispersive X-ray spectrometer analyses, we observed In-contained metallic interface between the p-GaN layer and the pure ITO contact layer after annealing at 600 degrees C. It revealed that ITO would react at interface or indiffuse near the interface at 600 C. The LED was degraded with unstable interfaces after life tests (stressed by a 50-mA current injection). To improve the reliability of GaN-based LEDs with the ITO contact layer, we suggest that the NiO layer be used to prevent the reaction and block the leakage pathway. (c) 2006 The Electrochemical Society.
The role of mammalian Ste20-like kinase MST3 in apoptosis
(2001-03-07)
Yuan, CJ
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Hsu, CY
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Huang, CYF
;
交大名義發表
;
National Chiao Tung University
Thermal annealing effect of indium tin oxide contact to GaN light-emitting diodes
(2005-10-01)
Hsu, CY
;
Lan, WH
;
Wu, YCS
;
材料科學與工程學系
;
Department of Materials Science and Engineering
We have fabricated GaN-based light-emitting diodes (LEDs) using transparent indium tin oxide (ITO) for p-type contacts. The current-voltage (I-V) characteristics of the devices have been studied. When annealed at 700 degrees C, the p-n junction of the diodes became very leaky, and even electrical short circuits have been observed. According to scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometer analyses (EDS), it was found that indium (In) diffused into the LED structure with defects such as threading dislocations (TDs) or V-pits. The defects provide leakage paths to cause short circuits in p-n junctions at high annealing temperatures.
Thermal gradient in solder joints under electrical-current stressing
(2004-11-01)
Shao, TL
;
Chiu, SH
;
Chen, C
;
Yao, DJ
;
Hsu, CY
The thermal gradient and temperature increase in SnAg3.5 solder joints under electrical-current stressing have been investigated by thermal infrared microscopy. Both positive and negative thermal gradients were observed under different stressing conditions. The magnitude of the thermal gradient increases with the applied current. The measured thermal gradients reached 365degreesC/cm as powered by 0.59 A, yet no obvious thermal gradient was observed when the joints were powered less than 0.25 A. The temperature increase caused by joule heating was as high as 54.5degreesC when powered by 0.59 A, yet only 3.7degreesC when stressed by 0.19 A. The location of heat generation and path of heat dissipation are believed to play crucial roles in the thermal gradient. When the major heat source is the Al trace, the thermal gradient in the solder bumps is positive; but it may become negative because the heat generated in the solder itself is more prominent.
Ultrafine platinum nanoparticles uniformly dispersed on arrayed CNx nanotubes with high electrochemical activity
(2005-07-12)
Sun, CL
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Chen, LC
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Su, MC
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Hong, LS
;
Chyan, O
The structure and electrochemical properties of arrayed nitrogen-containing carbon nanotube (CN, NT)-platinum nanoparticle (Pt NP) composites directly grown on Si substrates have been investigated. The CN., nanotube arrays were grown by microwave-plasma-enhanced chemical vapor deposition first and then acted as the template and support for Pt dispersion in the following sputtering process. Under the same sputtering conditions, it was found that well-separated Pt NPs would form with an average diameter of 2 nm on the arrayed NTs while a continuous Pt thin film was observed on the bare Si substrate. X-ray photoelectron spectroscopy (XPS), X-ray diffraction, and electron microscopy were employed to study bonding and structure changes with increasing deposition time. Implications of the C1s and N1s bonding changes in XPS and their possible relation to the NT-Pt composite structures with self-limited size distribution are discussed. Cyclic voltammograms show well-behaved curves in methanol oxidation, suggesting an efficient electronic conduction mechanism from the substrate via CN, NTs to reach individual Pt NPs is in operation. Such an integrated nanocomposite approach possesses a high potential for micro direct methanol fuel cell applications.
Vector compacation for power estimation with grouping and consecutive sampling techniques
(2002)
Hsu, CY
;
Shen, WZ
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We propose a high efficiency and high accuracy power estimation method for CMOS combinational circuits with grouping and consecutive sampling techniques. We separate input pattern pairs into several groups according to their power characteristics. The consecutive sampling skill is applied to find a shorter subsequence from the original input sequence. Our experimental results demonstrate that the compaction ratios are 1,250(min) and 154(min) with power estimation errors of 3.31%(avg) and 3.32%(avg) for two sampling strategies.