Browsing by Author "Kuo, SY"

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A new probabilistic induction method
(1997-02-01)
Hou, RH
;
Hong, TP
;
Tseng, SS
;
Kuo, SY
;
資訊工程學系
Knowledge acquisition by interviewing a domain expert is one of the most problematic aspects of the development of expert systems. As an alternative, methods for inducing concept descriptions from examples have proven useful in eliminating this bottleneck. In this paper, we propose a probabilistic induction method (PIM), which is an improvement of the Chan and Wong method, for detecting relevant patterns implicit in a given data set. PIM uses the technique of residual analysis and several heuristics to effectively detect complex relevant patterns and to avoid the problem of combinatorial explosion. A reasonable trade-off between the induction time and the classification ratio is achieved. Moreover, PIM quickly classifies unknown objects using classification rules converted from the positively relevant patterns detected. Three experiments are conducted to confirm the validity of PIM.
A new probabilistic induction method
(1997-02-01)
Hou, RH
;
Hong, TP
;
Tseng, SS
;
Kuo, SY
;
資訊工程學系
Knowledge acquisition by interviewing a domain expert is one of the most problematic aspects of the development of expert systems. As an alternative, methods for inducing concept descriptions from examples have proven useful in eliminating this bottleneck. In this paper, we propose a probabilistic induction method (PIM), which is an improvement of the Chan and Wong method, for detecting relevant patterns implicit in a given data set. PIM uses the technique of residual analysis and several heuristics to effectively detect complex relevant patterns and to avoid the problem of combinatorial explosion. A reasonable trade-off between the induction time and the classification ratio is achieved. Moreover, PIM quickly classifies unknown objects using classification rules converted from the positively relevant patterns detected. Three experiments are conducted to confirm the validity of PIM.
A testing framework for Web application security assessment
(2005-08-05)
Huang, YW
;
Tsai, CH
;
Lin, TP
;
Huang, SK
;
Lee, DT
The rapid development phases and extremely short turnaround time of Web applications make it difficult to eliminate their vulnerabilities. Here we study how software testing techniques such as fault injection and runtime monitoring can be applied to Web applications. We implemented our proposed mechanisms in the Web Application Vulnerability and Error Scanner (WAVES)-a black-box testing framework for automated Web application security assessment. Real-world situations are used to test WAVES and to compare it with other tools. Our results show that WAVES is a feasible platform for assessing Web application security. (c) 2005 Elsevier B.V. All rights reserved.
Catalyst-free GaN nanorods grown by metalorganic molecular beam epitaxy
(2006-05-01)
Kuo, SY
;
Kei, CC
;
Hsiao, CN
;
Chao, CK
;
Lai, FI
High-density GaN nanorods with outstanding crystal quality were grown on c-sapphire substrates by radio-frequency plasma-assisted metalorganic molecular beam epitaxy under catalyst- and template-free growth condition. Morphological and structural characterization of the GaN nanorods was employed by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy (HRTEM). These results indicate that the rod number density can reach 1 x 10(10) cm(-2) and the nanorods are well-aligned with preferentially oriented in the c-axis direction. Meanwhile, no metallic (Ga) droplet was observed at the end of the rods, which is the intrinsic feature of vapor-liquid-solid method. Nanorods with no traces of any extended defects, as confirmed by TEM, were obtained as well. In addition, optical investigation was carried out by temperature- and power-dependent micro-photoluminescence (mu-PL). The PL peak energies are red-shifted with increasing excitation power, which is attributed to many-body effects of free carriers under high excitation intensity. The growth mechanism is discussed on the basis of the experimental results. Catalyst-free GaN nanorods presented here might have a high potential for applications in nanoscale photonic devices.
Converter-free multiple-voltage scaling techniques for low-power CMOS digital design
(2001-01-01)
Yeh, YJ
;
Kuo, SY
;
Jou, JY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Recent research has shown that voltage scaling is a very effective technique for low-power design. This paper describes a voltage scaling technique to minimize the power consumption of a combinational circuit. First, the converter-free multiple-voltage (CFMV) structures are proposed, including the p-type, the n-type, and the two-way CFMV structures. The CFMV structures make use of multiple supply voltages and do not require level converters. In contrast, previous works employing multiple supply voltages need level converters to prevent static currents, which may result in large power consumption. In addition, the CFMV structures group the gates with the same supply voltage in a cluster to reduce the complexity of placement and routing for the subsequent physical layout stage. Next, we formulated the problem and proposed an efficient heuristic algorithm to solve it. The heuristic algorithm has been implemented in C and experiments were performed on the ISCAS85 circuits to demonstrate the effectiveness of our approach.
Decreasing giant splitting of longitudinal and transverse optical phonons in PbxSr1-xTiO3 due to Pb covalency
(2002-10-14)
Kuo, SY
;
Li, CT
;
Hsieh, WF
;
光電工程學系
;
Department of Photonics
In contrast to the increase of giant splitting of longitudinal optical (LO) and transverse optical (TO) phonons in polycrystalline BaxSr1-xTiO3 [Phys. Rev. B. 64, 224103-1 (2001)], a decreasing splitting of the softest A(1)(1TO) and the hardest A(1)(3LO) was observed in PbxSr1-xTiO3. A similar structure but anomalous discrepancies in lattice dynamics of ABO(3) perovskite are related to the diverse electronic states of Pb2+ and Ba2+ ions. In this article, Pb-O interaction is proposed to be more hybridized than Ba-O, and thus the change of effective charge to the LO-TO splitting may be the dominant mechanism in PbxSr1-xTiO3, while unit-cell volume change is in the BaxSr1-xTiO3 systems. (C) 2002 American Institute of Physics.
Dependence of luminescence efficiency on dopant concentration and sintering temperature in the erbium-doped Ba0.7Sr0.3TiO3 thin films
(2002-08-15)
Kuo, SY
;
Chen, CS
;
Tseng, TY
;
Chang, SC
;
Hsieh, WF
We found the dependence of luminescence efficiency on Er3+ concentration and sintering temperature in the Er-doped Ba0.7Sr0.3TiO3 (BST) thin films is governed by crystallinity and ion-ion interaction. X-ray diffraction and Raman studies of the sol-gel prepared samples show that the BST polycrystalline phase occurred when the sintering temperature reaches 700 degreesC, whereas, it becomes worse for temperature above 700 degreesC resulting from phase separation and the Er3+ concentration exceeding 3 mol % due to charge compensation mechanism. The observed green emission reaches maximum at sintering temperature 700 degreesC and 3 mol % Er3+ ions concentration. We also showed the Er dopant does not affect the dielectric property of BST thin films in C-V measurement and the Ba0.7Sr0.3TiO3 films doped with Er3+ ions may have potential use for electroluminescence devices. (C) 2002 American Institute of Physics.
Direct evidence of open ray orbits in a square two-dimensional resonator of dye-doped polymers
(2004-07-15)
Chern, GD
;
Poon, AW
;
Chang, RK
;
Ben-Messaoud, T
;
Alloschery, O
Lasing has been observed in optically pumped 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyrl)-4H-pyran-doped poly(methyl methacrylate) square-shaped micropillars that allow four-bounce closed and open ray orbits with internal incident angle theta(inc) > theta(c) (the critical angle for total internal reflection) and with the associated surface waves that emit at the four corners. We also detect strongly TE-polarized and spatially varying omission from the square sidewalls that is due to leaky open ray orbits with theta(inc) near but less than theta(c) for two of the four bounces. By selectively pumping the square microcavity with a stripe-shaped beam, we excite different four-bounce ray orbits. (C) 2004 Optical Society of America.
Direct experimental evidence of hybridization of Pb states with O 2p states in ferroelectric perovskite oxides
(2005-07-04)
Jan, JC
;
Tsai, HM
;
Pao, CW
;
Chiou, JW
;
Asokan, CK
This work presents the O K- and Ti L-3,L-2-edge x-ray absorption near-edge structure (XANES) spectra of PbxSr1-xTiO3 (PxSTO) and BaxSr1-xTiO3 (BxSTO) compounds with various Pb and Ba concentrations. The result provides direct evidence that the Pb-O bonding strongly affects O 2p-Ti 3d hybridization in the TiO6 octahedron of PxSTO. In contrast, the Ba-O bonding does not substantially affect O 2p-Ti 3d hybridization in BxSTO. The Ti L-3-edge XANES spectra show the splitting of the e(g) band for PxSTO with x greater than or similar to 0.5, which provides an evidence of Pb-induced tetragonal distortion in the TiO6 octahedron. In contrast, e(g) band splitting is absent in BxSTO. (c) 2005 American Institute of Physics.
Effect of annealing on the structural and optical properties of AgGaS2 thin films prepared by pulsed laser deposition
(2002-11-01)
Hsu, HC
;
Chen, HH
;
Kuo, SY
;
Chang, CS
;
Hsieh, WF
The influence of annealing on the AgGaS2 films groom by pulsed laser deposition has been investigated. The X-ray diffraction results show the AgGaS2 films were found with preferential orientation (1 1 2) normal to the surface and silver droplets,were diminished after the post-annealing. Photoluminescence (PL) measurements reveled the exciton energy is slightly red shifted that is possibly due to the thermal strain effect. The binding energy of the shallow, donors is similar to28 meV determined from temperature dependent PL spectra, In addition, the A-exciton and the B/C-exciton could be observed in the transmittance spectra at room temperature. (C) 2002 Elsevier Science B.V. All rights reserved.
Effect of rapid thermal annealing on beryllium implanted p-type GaN
(2004-03-25)
Huang, HW
;
Kao, CC
;
Tsai, JY
;
Yu, CC
;
Chu, CF
We report the results of rapid thermal annealing (RTA) effect on beryllium implanted in situ activated p-type GaN samples and investigate the ramping and isothermal annealing effect of RTA process for these samples. It is found that the optimum RTA condition is at the temperature of 1100 degreesC for 15 s. Furthermore, with equal total isothermal time of 60 s, we compared the multiple step annealing (MSA) at 1100 degreesC for four periods with single step annealing (SSA) for one period at the same annealing temperature of 1100 degreesC, and observed that the ramping effect with MSA could repair Be-related complex defect, and one time, long period isothermal annealing effect with SSA seems to induce much more defect. It seems that the multiple step annealing is more effective and induce less defect than single step annealing for Be-implanted in situ activated p-type GaN samples. (C) 2004 Elsevier B.V. All rights reserved.
Effect of the Ca content on the electronic structure of Pb1-xCaxTiO3 perovskites
(2003-10-20)
Jan, JC
;
Kumar, KPK
;
Chiou, JW
;
Tsai, HM
;
Shih, HL
This study performs O K- and Ti L-3,L-2-edge x-ray absorption near-edge structure (XANES) measurements and first-principles pseudopotential calculations for the electronic structures of ABO(3)-type Pb1-xCaxTiO3 (x=0-1) perovskites. The features in the O K-edge XANES spectra are found to be contributed primarily by hybridization between O 2p and Ti 3d, Pb 6p, and Ca 3d orbitals. The O K-edge XANES spectra reveal that partial substitution of A cations, Pb, by Ca not only decreases O 2p-Pb 6p but also O 2p-Ti 3d hybridization. The Ti L-3,L-2-edge measurements find that the off-center displacement of Ti, and hence, ferroelectricity persist up to a Ca concentration between 0.3 and 0.4. (C) 2003 American Institute of Physics.
Effects of doping concentration and annealing temperature on properties of highly-oriented al-doped ZnO films
(2006-01-18)
Kuo, SY
;
Chen, WC
;
Lai, FI
;
Cheng, CP
;
Kuo, HC
Transparent and conductive high-preferential c-axis-oriented Al-doped zinc oxide (ZnO:Al, AZO) thin films have been prepared by the sol-gel route. Film deposition was performed by spin-coating technique on Si(1 0 0) and glass substrate. Structural, electrical and optical properties were performed by XRD, SEM, four-point probe, photoluminescence (PL) and UV-VIS spectrum measurements. The effects of annealing temperature and dopant concentration on the structural and optical properties are well discussed. It was found that both annealing temperature and doping concentration alter the microstructures of AZO films. Also, PL spectra show two main peaks centered at about 380 nm (UV) and 520 nm (green). The variation of UV-to-green band emission was greatly influenced by annealing temperatures and doping concentration. Reduction in intensity ratio of UV-to-green might possibly originate from the formation of Al-O bonds and localized Al-impurity states. The minimum sheet resistance of 10(4)ohm/rectangle was obtained for the film doped with 1.6mol% Al, annealed at 750 degrees C. Meanwhile, all AZO films deposited on glass are very transparent, between 80% and 95% transmittance, within the visible wavelength region. These results imply that the doping concentration did not have significant influence on transparent properties, but improve the electrical conductivity and diversify emission features. (c) 2005 Elsevier B.V. All rights reserved.
Enhanced light output in InGaN/GaN light emitting diodes with excimer laser etching surfaces
(2006-04-01)
Huang, HW
;
Chu, JT
;
Kao, CC
;
Hsueh, TH
;
Lu, TC
The InGaN/GaN light-emitting diode (LED) with a top p-GaN surface nanoroughened using Ni nanomasks and laser etching has been fabricated. The light output power of the InGaN/GaN LED with a nanoroughened top p-GaN surface is 1.55-fold that of a conventional LED. The series resistance of InGaN/GaN LED was reduced by 32% due to the increase in the contact area of the nanoroughened surface.
Fabrication of magnesium-doped gallium nitride nanorods and microphotoluminescence characteristics
(2006-05-01)
Lai, FI
;
Kuo, SY
;
Chang, YH
;
Huang, HW
;
Chang, CW
High density magnesium (Mg)-doped gallium nitride (GaN) nanorods were fabricated by inductively coupled plasma reactive ion etching technique from the epitaxial film. Under the fixed Cl-2/Ar flow rate of 10/25 SCCM (SCCM denotes cubic centimeter per minute at STP) and inductively coupled plasma/bias power of 200/200 W, the nanorods were fabricated with a density of 10(8)-10(10) cm(2) and dimension of 20-100 nm by varying the chamber pressure from 10 to 30 mTorr. A large blueshift was observed in the photoluminescence (PL) peak energy of Mg-doped GaN nanorods under HeCd laser (325 nm) excitation. The PL spectra of nanorods show a typical donor-acceptor-pair emission around 3.0 eV with a large blueshift compared to the Mg-doped GaN film. The blueshift energy increases from 8 to 67 meV as the excitation intensity varies from 12 to 56 kW/cm(2). Possible reasons causing the power dependence of spectral shift in the PL emission energy are discussed. 2006 American Vacuum Society.
Lattice dynamics of perovskite PbxCa1-xTiO3
(2004-05-01)
Kuo, SY
;
Li, CT
;
Hsieh, WF
;
光電工程研究所
;
Institute of EO Enginerring
Investigation of the structural and vibrational properties of the PbxCa1-xTiO3 (PCT) system exhibits two phase transitions in the range of x=0-1 by using x-ray powder diffraction and Raman spectroscopy. The first transition occurring at xsimilar to0.65 corresponds to the tetragonal-to-cubic phase and the second one occurs near x=0.35 is attributed to the orthorhombic-to-cubic phase. The absence of the intermediate tetragonal phase between orthorhombic and cubic phases (0
Proton pumping inorganic pyrophosphatase of endoplasmic reticulum-enriched vesicles from etiolated mung bean seedlings
(2005-02-01)
Kuo, SY
;
Chien, LF
;
Hsiao, YY
;
Van, RC
;
Yan, KH
Endoplasmic reticulurn (ER)-enriched vesicles from etiolated hypocotyts of mung bean seedlings (Vigna radiata) were successfully isolated using Ficoll gradient and two-phase (polyethylene glycol-dextran) partition. The ER-enriched vesicles contained inorganic pyrophosphate (PPi) hydrolysis and its associated proton translocating activities. Antiserum prepared against vacuolar H+-pyrophosphatase (V-PPase, EC 3.6.1.1) did not inhibit this novel pyrophosphatase-dependent proton translocation, excluding the possible contamination of tonoptast vesicles in the ER-enriched membrane preparation. The optimal ratios of Mg2+/PPi (inorganic pyrophosphate) for enzymatic activity and PPj-dependent proton translocation of ER-enriched vesicles were, higher than those - of vacuolar membranes. The PPj-dependent Proton translocation of ER-enriched vesicles absolutely required the presence of monovalent cations with preference for K but could be inhibited by a common PPase inhibitor, F-. Furthermore, ER H+-pyrophosphatase exhibited some similarities and differences to vacuolar H+-PPases in cofactor/substrate ratios, pH profile, and concentration dependence of F-, imidodiphosphate (a PPj anatogue), and various chemical modifiers.
Static power analysis for power-driven synthesis
(1998-03-01)
Yuan, SY
;
Chen, KH
;
Jou, JY
;
Kuo, SY
;
電子工程學系及電子研究所
A new static power analysis method for CMOS combinational circuits is presented. This approach integrates the simulation-based method and the plobabilistic method, and can establish the relationships between the primary inputs and the internal nodes in the circuit. Based on the relationships, our approach can also indicate which internal node or input sequence consumes the most power. It is thus suitable for performing power estimation in the synthesis environment for power optimisation. To the best of our knowledge, this is the first attempt to develop a systematic way to symbolically represent the relationships between the primary inputs and the power consumption at every internal node of a circuit. Furthermore, by using the existing piecewise linear delay model, as well as the proposed algorithm, this novel method is also very accurate and efficient. For a set of benchmark circuits, the experimental results show that the power estimated by our technique is within 5% error as compared with that by the exact SPICE simulation, while the execution speed is more than four orders of magnitude speed is faster.
Structural and optical properties of erbium-doped Ba0.7Sr0.3TiO3 thin films
(2005-07-01)
Kuo, SY
;
Hsieh, WF
;
光電工程學系
;
Department of Photonics
Er-doped Ba0.7Sr0.3TiO3 (BST:Er) thin films prepared by the sol-gel technique have been investigated by means of x-ray diffraction (XRD), Raman, spectroscopic ellipsometry, Capacitance-voltage, and photoluminescence (PL) measurements. XRD results indicate that the film possess the highest degree of crystallinity at the annealing temperature of 700 degrees C. The dependence of the refractive index on erbium concentration was also analyzed. In addition, the excitation-dependent PL studies indicate that the green emission peaks do not shift with the change in excitation power, while the integrated intensity increases monotonically with the increase in excitation power. The quenching mechanism of the green emission due to dopant concentrations and annealing temperatures was discussed in detail. All experimental results indicate that BST:Er thin films might be a potential candidate for optoelectronics devices. (c) 2005 American Vacuum Society.
Structural ordering transition and repulsion of the giant LO-TO splitting in polycrystalline BaSr1-xTiO3
(2001-12-01)
Kuo, SY
;
Liao, WY
;
Hsieh, WF
;
光電工程研究所
;
Institute of EO Enginerring
We report Raman and x-ray diffraction studies of polycrystalline BaxSr1-xTiO3 (BST) prepared by the sol-gel technique in the range of x = 0 to 1.0. Other than a tetragonal to cubic phase transition at composition x approximate to0.75 of the BST powders detected by x-ray diffraction and Raman spectroscopy, a new structural ordering transition around x approximate to0.4-0.5 is observed due to the atomic arrangement. By taking the anharmonic coupling between the three A(1) (TO) modes into account, the observed repulsion of the giant LO-TO splitting is a result of decreasing cell dimension and strengthening the electron-phonon coupling. The results help us to explain the weakening of the ferroelectricity in the BST tetragonal phase as x decreases. The anomalous inconsistency in our experimental results and theoretical prediction are attributed to the lack of detailed information of dynamical effective charges in the BaxSr1-xTiO3 compounds.