Browsing by Author "Liu, YC"

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A general approach to compute the probabilities of unresolved clones in random pooling designs
(2004)
Hwang, FK
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Liu, YC
;
應用數學系
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Department of Applied Mathematics
In this paper, we develop a general approach to compute the probabilities of unresolved clones in random pooling designs. This unified and systematic approach gives better insight for handling the dependency issue among the columns and among the rows. Consequently, we identify some faster computation formulas for four random pooling designs proposed in the literature, and we derive some probability distribution functions of the number of unresolved clones that were not available before.
A new insight into the degradation mechanisms of various mobility-enhanced CMOS devices with different substrate engineering
(2005)
Chung, SS
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Liu, YR
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Wu, SJ
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Lai, CS
;
Liu, YC
In this paper, the difference in degradation mechanism for different substrate engineered CMOS devices has been reported for the first time. These two different substrate engineering includes hybrid substrate engineering, with (100) and (110) orientations, and strained-Si devices. Different mechanisms are responsible for these two different mobility enhancement schemes. For strained-Si devices, it shows that the dominant mechanism for HC(Hot Carrier) and NBT (Negative Bias Temperature) degradations is attributed to the lateral electric field resulting from the mobility enhancement. While for (110)/(100) substrate engineered devices, the dominant mechanism is due to the dangling bond of the surface. In other words, for (I I 0)/(l 00) substrate, the device degradation is weakly dependent on the mobility enhancement while largely dependent on the bond strength. Finally, the difference in temperature dependence of HC and NBT has also been observed for both strained-Si and (110)/(100) substrate devices. Sophisticated measurement techniques, charge pumping (CP) and gated-diode (GD) measurement, have been employed to understand these device mechanisms. These results provide a guideline for the device design and the understanding of related reliabilities in the popular strained-Si and hybrid substrate technology CMOS devices.
Anisotropic O 2p-Mn 3d unoccupied states in La1-xMnO3: an X-ray absorption spectroscopy study
(2002-02-01)
Lin, JY
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Chen, CW
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Liu, YC
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Liu, SJ
;
Wu, KH
We have studied La1-xMnO3 thin films, which show the metal-insulator transition similar to La1-xCaxMnO3. The transport and magnetic properties are measured, X-ray absorption spectroscopy is employed to investigate the electronic structure. Surprisingly, the electronic structure of La1-xMnO3 shows large anisotropy. Our results suggest that La1-xMnO3 is unique among manganites. (C) 2002 Elsevier Science B.V. All rights reserved.
Cost benefit analysis of series systems with warm standby components and general repair time
(2005-06-01)
Wang, KH
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Liu, YC
;
Pearn, WL
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工業工程與管理學系
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Department of Industrial Engineering and Management
We study the availability analysis of three different series system configurations with warm standby components and general repair times. The time-to-failure for each of the primary and warm standby components is assumed to be exponentially distributed with respective parameter λ and α. This paper presents a recursive method, using the supplementary variable technique and treating the supplementary variable as the remaining repair time, to develop the steady-state probability distribution of the number of working components in the system. We develop the explicit expressions for the steady-state availability, Aν, for three configurations and perform comparisons. For all three configurations, comparisons are made for specific values of distribution parameters and of the cost of the components. The configurations are ranked based on Aν and cost/benefit, for three various repair time distributions: exponential, 3-stage Erlang, and deterministic, where benefit is Aν.
Design of a wide-band frequency synthesizer based on TDC and DVC techniques
(2002-10-01)
Hsu, T
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Hsu, TR
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Wang, CC
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Liu, YC
;
Lee, CY
A wide-band frequency synthesizer based on time-to-digital (TDC) and digital-to-voltage (DVC) conversion techniques is proposed here. The proposed frequency synthesizer has the capabilities of jitter reduction and large bandwidth, making it more robust for high-frequency applications. A test chip is designed and fabricated in 0.6-mum CMOS single-poly triple-metal process. Here, the novel DVC circuit is realized by tristate inverters, where the resolution can achieve 0.2 mV. Control stability of jitter can improve about 24 dB by exploiting the TDC-based controller. In order to achieve high output frequency and large output range, an analog voltage-controlled oscillator is designed to provide a locked range from 900 to 1900 MHz with < 22 kHz resolution at 3.3 V. Simulation and test results show that the proposal can work as expected. Moreover, the TDC-based controller can be treated as soft IP to speed up turnaround time.
Detection of foot and mouth disease and porcine reproductive and respiratory syndrome viral genes using microarray chip
(2006-02-01)
Liu, YC
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Huang, GS
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Wu, MC
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Hong, MY
;
Hsiung, KP
Two viral pathogens, namely, porcine reproductive and respiratory syndrome virus (PRRSV) and foot and mouth disease virus (FMDV), were selected as models for multiple pathogen detection in a cDNA microarray. Two signature regions selected from ORF2 (around 500 bp) and ORF5 (around 600 bp) of PRRVS (America serotype), and one signature region from structural genes VP1 (around 500 bp) of FMDV type O were designed and spotted on a nylon membrane. For PCR sensitivity study, the cloned FMDV-VP1 template could be diluted to near one copy and its PCR product was still detectable in gel electrophoresis. In the microarray detection, the labelling FMDV probes (3 mg/ml) could be diluted 320 times and still maintained a visible colour when hybridized with the chip. Using the mixing primers, the microarray chip demonstrated rapid and accurate detection of the specific genes. To our knowledge, this preliminary study is the first example reported applying the long signature sequences to the multiple pathogen detection in cDNA microarray.
Electromigration in eutectic SnPb solder bumps with Ni/Cu UBM
(2005)
Chiu, SH
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Liang, SW
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Chen, C
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Lin, SS
;
Chou, CM
This study investigates the electromigration behavior of eutectic SnPb solder bumps with Ni/Cu UBM, in which the thickness of the Ni and Cu layer is 3 pm and 5 pm, respectively. It was found that the SnPb solderjoints have better electromigration resistance than that of SnAg bumps with thin film UBM. The thermal characteristic of SnPb solder joints under current stressing was measured by infrared technique. The Joule heating effect was less serious due to the wide Al trace of 100 mu m. Besides, a three-dimensional simulation on current density distribution was performed to examine the current crowding behavior in the joint. The results show that the current crowding occurs at the entrance point of the Al trace, which caused higher formation rate of intermetallic compounds there, and thus open failure occurred.
Enhancement of imidization of poly(amic acid) through forming poly(amic acid)/organoclay nanocomposites
(1999-08-01)
Tyan, HL
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Liu, YC
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Wei, KH
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材料科學與工程學系
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Department of Materials Science and Engineering
The imidization kinetics of nanocomposites of poly(amic acid) and organoclay were analyzed with in situ Fourier Transform Infrared spectra at several temperatures. The poly(amic acid) studied consisted of pyromellitic dianhydride and 4,4'-oxydianiline. It was found that by dispersing a small amount of organoclay in nanometer scale in the poly(amic acid), both the imidization temperature and the imidization time of the poly(amic acid) can be reduced dramatically. In specific, when two parts of exfoliated silicate layers of organoclay was dispersed in the poly(amic acid), the imidization temperature was lowered by 50 degrees C (250 degrees C versus 300 degrees C) for achieving a complete imidization. Additionally, the imidization time of the poly(amic acid) at 250 degrees C can be reduced to 15 min when the amount of organoclay increased to seven parts. Using a first-order reaction to model the imidization kinetics of poly(amic acid)/organoclay, a 20% drop in the activation energy for imidization of PMDA-ODA/organoclay (7 phr) was obtained as compared to that for imidization of neat PMDA-ODA. (C) 1999 Elsevier Science Ltd. All rights reserved.
Error-tolerant pooling designs with inhibitors
(2003)
Hwang, FK
;
Liu, YC
;
應用數學系
;
Department of Applied Mathematics
Pooling designs are used in clone library screening to efficiently distinguish positive clones from negative clones. Mathematically, a pooling design is just a nonadaptive group testing scheme which has been extensively studied in the literature. In some applications, there is a third category of clones called "inhibitors" whose effect is to neutralize positives. Specifically, the presence of an inhibitor in a pool dictates a negative outcome even though positives are present. Sequential group testing schemes, which can be modified to three-stage schemes, have been proposed for the inhibitor model, but it is unknown whether a pooling design (a one-stage scheme) exists. Another open question raised in the literature is whether the inhibitor model can treat unreliable pool outcomes. In this paper, we answer both open problems by giving a pooling design, as well as a two-stage scheme, for the inhibitor model with unreliable outcomes. The number of pools required by our schemes are quite comparable to the three-stage scheme.
Fungichromin: A substance from Streptomyces padanus with inhibitory effects on Rhizoctonia solani
(2003-01-01)
Shih, HD
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Liu, YC
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Hsu, FL
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Mulabagal, V
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Dodda, R
Streptomyces padanus strain PMS-702 is an antagonist of Rhizoctonia solani AG-4, the causal agent of damping-off of cabbage. Treatment of cabbage seeds with the culture filtrate of S. padanus strain PMS-702 was effective in reducing the incidence of damping-off of cabbage. The major active ingredient from the culture filtrate of S. padanus strain PMS-702 was purified by silica gel column chromatography and identified as the polyene macrolide, fungichromin, by NMR and mass spectral data. Bioassay studies showed that fungichromin had a strong antifungal activity against R. solani AG-4, and its minimum inhibitory concentration (over 90% inhibition) was found to be 72 mug/mL. This is the first report of fungichromin from S. padanus as an active ingredient for the control of Rhizoctonia damping-off of cabbage.
Nanoimprinting-lithography-induced self-aligned liquid crystals for novel multifunctional optical films
(2006-02-13)
Chiu, CH
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Kuo, HL
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Chen, PC
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Wen, CH
;
Liu, YC
Polymerizable nematic liquid crystal (LC) was adopted as a resist for our newly developed nanoimprinting lithography process. Liquid crystal molecules were self-aligned during imprinting process without precoated alignment layer. The large patterned area was able to achieve 4x4 cm(2) at very low impriting pressure, 1.5 bar. The optical anisotropic was verified through polarized optical microscopy and the retardation was measured by polarized ultraviolet/visible spectrometer. The micrograted LC films prepared by this novel method offer the potential applications for a LC alignment layer within LC cells, as well as preparation of optical anisotropic films. (c) 2006 American Institute of Physics.
Optical birefringence and polarization dependent loss of square- and rectangular-lattice holey fibers with elliptical air holes: numerical analysis
(2005-01-10)
Liu, YC
;
Lai, Y
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光電工程學系
;
Department of Photonics
Polarization dependent leakage loss as well as optical birefringence for the fundamental mode in square- and rectangular-lattice holey fibers with elliptical air holes are studied numerically based on the full-vector finite element method for the first time. It is shown that high birefringence in the order of 10(-2) and large polarization dependent loss required for single-polarization single-mode transmission are both achievable by using the proposed structure. (C) 2005 Optical Society of America.
Random pooling designs under various structures
(2003-12-01)
Hwang, FK
;
Liu, YC
;
應用數學系
;
Department of Applied Mathematics
Balding et al. ( 1995) showed that randomizing over the k-set space yields much better pooling designs than the random pooling design without the k-restriction. A natural question arises as to whether a smaller subspace, i.e., a space with more structure, will yield even better results. We take the random subset containment design recently proposed by Macula, which randomizes over a subspace of the k-set space, as our guinea pig to compare with the k-set space. Unfortunately the performance of the subset containment design is hard to analyze and only approximations are given. For a set of parameters, we are able to produce either an exact analysis or very good approximations. The comparisons under these parameters seem to favor the k-set space.
Single polarization mode transmission of square-lattice holey fibers with elliptical air holes: Numerical analysis
(2005)
Lai, YC
;
Liu, YC
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光電工程學系
;
Department of Photonics
Square-lattice holey fiber structures with elliptical air-holes for single polarization mode transmission by maintaining a large polarization dependent loss coefficient ratio are identified numerically based on the full-vector finite-element method.
Sortability of vector partitions
(2003-02-28)
Hwang, FK
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Lee, JS
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Liu, YC
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Rothblum, UG
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應用數學系
Some combinatorial properties of partitioning points in R-1 have recently been well studied. We extend this study to points in R-d with the hope to benefit clustering and optimal partition problems in R-d. (C) 2002 Elsevier Science B.V. All rights reserved.
The expected numbers of unresolved positive clones for various random pool designs
(2001)
Hwang, FK
;
Liu, YC
;
應用數學系
;
Department of Applied Mathematics
A pool design is random if it varies according to a probability distribution. There are four types of random design proposed in the literature: random incidence design, random k-set design, random distinct k-set design, and random k-size design. Recently Hwang gave an approximation to estimate the number of unresolved positives for random distinct k-set design. In this article, we give exact formulas for all four types of random designs for estimating the number of unresolved positives. We also do some numerical comparisons of the four designs.
Thermally and mechanically enhanced clay/polyimide nanocomposite via reactive organoclay
(1999-07-01)
Tyan, HL
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Liu, YC
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Wei, KH
;
材料科學與工程學系
;
Department of Materials Science and Engineering
High modulus and thermally stable clay/polyimide (pyromellitic dianhydride-4,4'-oxydianiline, PMDA-ODA) nanocomposites were synthesized from reactive organoclay and poly(amic acid). The reactive organoclay was formed by using p-phenylenediamine as a swelling agent for silicate layers of montmorillonite. The swelling process was first carried out through ion exchange between the onium of one amine end group of p-phenylenediamine and the sodium ion in montmorillonite. The other amine end group of p-phenylenediamine reacted with the dianhydride end group of poly(amic acid), producing an irreversible swelling. This irreversible swelling resulted in a nanostructured material containing intercalated nanometer silicate layers dispersed in PMDA-ODA as confirmed by both X-ray and transmission electron microscopy. The glass transition temperature and the thermal decomposition temperatures of this type of clay/PMDA-ODA are higher than that of pure PMDA-ODA. A 2,5-fold increase in the modulus of clay/PMDA-ODA film was obtained as compared to that of pure PMDA-ODA film. Both the maximum and the elongation-for-break of these clay/PMDA-ODA nanocomposites increased with the amount of organoclay. The maximum reduction in out-of-plane coefficient of thermal expansion of this type clay/PMDA-ODA was 50% as compared to that of pure PMDA-ODA.
Valence-band tunneling enhanced hot carrier degradation in ultra-thin oxide nMOSFETs
(2000)
Tsai, CW
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Gu, SH
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Chiang, LP
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Wang, TH
;
Liu, YC
Enhanced hot carrier degradation with stress V-g in the valence-band tunneling regime is observed. This degradation is attributed to channel hole creation by valence-band electron tunneling. The created holes provide for Auger recombination with electrons in the channel and thus increase hot electron energy. The valence-band tunneling enhanced hot carrier degradation becomes more serious as gate oxide thickness is reduced. In ultra-thin gate oxide nMOSFETs, our result shows that the valence-band tunneling enhanced degradation, as opposed to max. Tb stress induced degradation, exhibits positive dependence on substrate bias. This phenomenon may cause a severe reliability issue in positively biased substrate or floating substrate devices.