Browsing by Author "Chang, C. S."

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A tracking motion approach for a piezotube actuator in a disk drive subject to disk deformation and disturbance
(2007-10-01)
Chang, C. S.
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Liu, T. S.
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Tang, Y. C.
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機械工程學系
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Department of Mechanical Engineering
This study investigates the disk drive dynamics when a disk surface deforms and a disturbance force is exerted on a pickup head in near-field optical disk drives. Serving as an actuator, a piezotube is connected to the suspension of the pickup head. A model is constructed to investigate the pickup head dynamics. Equations of motion for focusing and track-following are derived in the presence of disk surface deformation and the disturbance force on the pickup head. A proportional and derivative control method is carried out in numerical examples. There exists a critical proportional gain that influences the number of resonances in the frequency spectra. Numerical results show that there is only one resonance or none in the frequency spectra when the proportional gain is larger than the critical proportional gain. Hence, the tracking error ratio becomes smaller than one within a wide frequency range, if few resonances appear in the frequency spectra.
ab initio calculated frequency-dependent nonlinear optical properties on CsGeBr3
(2006-01-01)
Tang, L. C.
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Chang, Y. C.
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Huang, J. Y.
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Chang, C. S.
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光電工程學系
A systematic first-principles calculation of the linear and second-order optical susceptibilities as functions of frequency for CsGeBr3 is presented. Specifically, we study the relation between the structural properties and the optical responses. Three structural deformation factors, Delta alpha, d(Ge), d(X) are used to express the degree of distortion from the ideal perovskite structure in bond angle, Ge position, and anion position, respectively. Based on our first-Principles studies, we find that Delta alpha and d(Ge) increase, while d(X) decreases as we substitute the halo-en ion from Cl to Br and then to I. The dielectric function and the second harmonic generation coefficient are also found to increase with increasing Delta alpha and d(Ge). Our calculation indicates that the direct bandgap, E-g, of CsGeX3 occurs at the R-point for all three compounds, and its magnitude decreases as Delta alpha and d(Ge) increase (i.e. E-g(CsGeI3) < E-g(CsGeBr3) < E-g(CsGeCl3)). Our partial density of states (PDOS) analysis reveals that the valence band maximun (VBM) and conduction band minimum (CBM) are mainly associated with the p-orbitals of Germanium. Interband and intraband analysed results for chi((2))(ijk) in CsGeBr3 can be separated into two main groups of peaks. One was contributed from the magnitude electronic bandgap; the other part was recognized to be attribution from the distortional structural factors. The magnitudes Of chi((2))(ijk) were in the same manner with some reported experiment near the band gap.
Accuracy analysis of the percentile method for estimating non normal manufacturing quality
(2007)
Wu, Chien-Wei
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Pearn, W. L.
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Chang, C. S.
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Chen, H. C.
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工業工程與管理學系
Vannman ( 1995) proposed a superstructure C-p(u, v) of capability indices for processes with normal distributions, which include C-p, C-pk, C-pm, and C-pmk as special cases. Pearn and Chen (1997) considered a generalization of C-p(u, v), called C-Np(u, v), to cover processes with non normal distributions. Pearn and Chen ( 1997) also proposed a sample percentile estimator for the generalization C-Np(u , v). In this article, we investigate the performance of the sample percentile estimator. We perform some simulation study, which covers the normal distribution and various non normal distributions including the uniform distribution, chi-square distribution, student's t distributions, F distribution, beta distribution, gamma distribution, Weibull distribution, lognormal distribution, triangular distribution, and Laplace distribution, with selected parameter values. Extensive simulation results, comparisons, and analysis are provided.
Development trends for insertion devices of future synchrotron light sources
(2011-04-28)
Hwang, C. S.
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Jan, J. C.
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Chang, C. S.
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Chen, S. D.
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Chang, C. H.
The in-vacuum undulator with a permanent magnet at room temperature is a mature technology and is widely used; with a short period length in a medium-energy facility, it can enhance photon brilliance in the hard x-ray region. A cryogenic permanent magnet has been investigated as an in-vacuum undulator; this undulator will become the best prospective device to satisfy the requirements of a photon source with great brilliance in the hard x-ray region. For the further hard x-ray region, a superconducting wiggler can provide great flux with a continuous spectrum, whereas a superconducting undulator will provide great brilliance with a discrete spectrum. High-temperature superconducting wires are highly promising for use in the development of superconducting undulators; unique algorithms for their development with an extremely short period in a small-magnet gap have been devised. Some out-of-vacuum planar undulators with special functions must also be fabricated to enable diverse applications in various light-source facilities. This article describes current and future developments for insertion devices in storage-ring and free-electron-laser facilities and discusses their feasibility for use therein.
Effect of Threading Dislocations on Local Contacts in Epitaxial ZnO Films
(2010)
Lin, C. Y.
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Liu, W. -R.
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Chang, C. S.
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Hsu, C. -H.
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Hsieh, W. F.
Local conductance of a ZnO epifilm with a columnar-grain structure was studied by conductive-mode atomic force microscopy. The probe-ZnO junction at the grain boundary with high density edge threading dislocations (TDs) behaves as a Schottky contact while the junction at the epitaxial core behaves as an ohmic contact, resulting in the nonuniformity of conductance throughout the film. The calculated Schottky barrier is 0.4 +/- 0.025 eV. The point defects of doubly charged Zn vacancies accumulated at the edge TDs induce local band bending of ZnO, thus contributing to the Schottky nature at the grain boundary.
Effects of electronic confinement and substrate on the low-temperature growth of Pb islands on Si(100)-2 x 1 surfaces
(2010-01-01)
Hsu, C. C.
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Lin, W. H.
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Ou, Y. S.
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Su, W. B.
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Chang, C. S.
The growth of Pb films on the Si(1 0 0)-2 x 1 surface has been investigated at low temperature using scanning tunneling microscopy Although the orientation of the substrate is (1 0 0), flat-top Pb islands with (1 1 1) surface can be observed The island thickness is confined within four to nine atomic layers at low coverage Among these islands. those with a thickness of six layers are most abundant Quantum-well states in Pb(1 1 1) islands of different thickness are acquired by scanning tunneling spectioscopy. They are found to be identical to those taken oil the Pb(1 1 1) islands grown oil the Si(1 1 1)7 x 7 surface. Besides Pb(1 1 1) islands. two additional types of Pb islands are formed. rectangular flat-top Pb(1 0 0) islands and rectangular three-dimensional (3D) Pb islands, and both their orientations rotate by 90 degrees from a terrace to the adjacent one This phenomenon implies that the structures of Pb(1 0 0) and 3D islands are influenced by the Si(1 0 0)-2 x 1 substrate (C) 2009 Elsevier B.V. All rights reserved
Investigation of Post-NBT Stress Current Instability Modes in HfSiON Gate Dielectric pMOSFETs by Measurement of Individual Trapped Charge Emissions
(2009)
Ma, H. C.
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Chiu, J. P.
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Tang, C. J.
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Wang, Tahui
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Chang, C. S.
Bipolar charge detrapping induced current instability in HfSiON gate dielectric pMOSFETs after negative bias and temperature stress is studied by using a fast transient measurement technique. Both single electron and single hole emissions are observed, leading to post-stress current degradation and recovery, respectively. The NBT stress voltage and temperature effect on post-stress current evolution is explored. Clear evidence of electron and hole trapping in NBT stress is demonstrated. A bipolar charge trapping/detrapping model and charge detrapping paths based on measured charge emission times are proposed.
Investigation of the electronic, linear and second-order nonlinear optical properties for the wide bandgap chalcopyrite ternary nitrides
(2008)
Tang, L. C.
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Chang, Y. C.
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Huang, J. Y.
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Chang, C. S.
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光電工程學系
We present the results of the ab initio calculated electronic properties, first and second harmonic generation for the A(II)B(IV) N(2), (A(II)=Be, B(IV)=C, Si, Ge) compounds with chalcopyrite structure performed using the Linear Augmented Slater-Type Orbitals (LASTO) method. The second-order optical susceptibilities as functions of frequency for A(II)B(IV)N(2) are also presented. Specifically, we study the relation between the structural properties and the optical responses. Our electronic band structure and density of states (PDOS) analysis reveal that the underestirnate bandgaps of these chalcopyrite A(II)B(IV)N(2) are wide enough (from 4eV to 6eV), direct transition and mainly located at F-point. Calcultion results show this new category wide-bandgap ternary nitrides has potential applications in optoelectronics.
LQG controller for active vibration absorber in optical disk drive
(2007-02-01)
Chang, C. S.
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Liu, T. S.
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機械工程學系
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Department of Mechanical Engineering
Unbalanced disks in rotation will lead to the main vibration of an optical disk drive. Passive vibration absorbers are usually used in current optical disk drives to suppress vibration. Generally, optical disk drives have to make a disk spin at multiple speeds by different read/write conditions. However, the passive vibration absorber only suppresses vibration at a specific rotating speed and may excite vibration at other speeds. This paper uses a linear quadratic Gaussian (LQG) controller for active vibration absorbers to reduce diskdrive vibration at multiple rotating speeds. The absorber with LQG control is validated based on simulation and experimental results.
Polar orientation induced by local photo-assisted poling in azo copolymer films
(2010-04-01)
Chien, F. S. -S.
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Lin, C. Y.
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Huang, C. R.
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Chang, C. S.
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Hsu, C. C.
Polar orientation created by local photo-assisted poling (PAP) in copolymer films containing disperse red 1 was investigated by scanning probe microscopy. PAP was performed by a proximal biased probe, and the polar orientation was semiquantitatively measured by electrostatic force microscopy. The polar orientation behaves as a biexponential function of the period of PAP, which is dominated by fast angular hole burning and slow angular redistribution (AR). The characteristic time of AR decreases linearly with the poling bias. An expression has been developed to interpret the evolution of the Lorentzian-like shape of the poled spots. A poled spot with 150 nm FWHM was demonstrated. (C) 2010 Optical Society of America
Polar orientation induced by local photo-assisted poling in azo copolymer films
(2010-04-01)
Chien, F. S. -S.
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Lin, C. Y.
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Huang, C. R.
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Chang, C. S.
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Hsu, C. C.
Polar orientation created by local photo-assisted poling (PAP) in copolymer films containing disperse red 1 was investigated by scanning probe microscopy. PAP was performed by a proximal biased probe, and the polar orientation was semiquantitatively measured by electrostatic force microscopy. The polar orientation behaves as a biexponential function of the period of PAP, which is dominated by fast angular hole burning and slow angular redistribution (AR). The characteristic time of AR decreases linearly with the poling bias. An expression has been developed to interpret the evolution of the Lorentzian-like shape of the poled spots. A poled spot with 150 nm FWHM was demonstrated. (C) 2010 Optical Society of America
Precision measures for processes with multiple manufacturing lines
(2006-10-01)
Pearn, W. L.
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Chang, C. S.
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工業工程與管理學系
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Department of Industrial Engineering and Management
Process capability indices C-p, and C-pk have been popularly used in the manufacturing industry for providing measures of process potential and performance. The precision index C-p is used to measure product quality consistency, while the yield index C-pk is used to provide measures of percentage of product conforming to manufacturing specifications. Properties of C-p for processes with a single manufacturing line have been investigated extensively. However, research on properties of C-p for processes with multiple manufacturing lines have been neglected. In this paper, we consider the precision index C-p for processes with three manufacturing lines. We develop a practical procedure for process precision testing to determine whether a process meets the precision requirement preset in the factory. An application example is given.
Single Domain m-Plane ZnO Grown on m-Plane Sapphire by Radio Frequency Magnetron Sputtering
(2012-10-01)
Lin, B. H.
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Liu, W. -R
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Lin, C. Y.
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Hsu, S. T.
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Yang, S.
High-quality m-plane orientated ZnO films have been successfully grown on m-plane sapphire by using radio frequency magnetron sputtering deposition. The introduction of a nanometer-thick, low-temperature-grown ZnO buffer layer effectively eliminates inclusions of other undesirable orientations. The structure characteristics of the ZnO epi-layers were thoroughly studied by synchrotron X-ray scattering and transmission electron microscopy (TEM). The in-plane epitaxial relationship between ZnO and sapphire follows (0002)(ZnO) parallel to (11 (2) over bar0)(sapphire) and (11 (2) over bar0)(ZnO) parallel to (0006)(sapphire) and the ZnO/sapphire interface structure can be described by the domain matching epitaxy along the [11 (2) over bar0](ZnO) direction. The vibrational properties of the films were investigated by polarization dependent micro-Raman spectroscopy. Both XRD and micro-Raman results reveal that the obtained m-ZnO layers are tinder an anisotropic biaxial strain but still retains a hexagonal lattice.
Standard 0.18um 1P6M CMOS IC foundry flow for accelerometer, analog readout circuit and wafer level capping package integration
(2011)
Huang, C. J.
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Chen, C. S.
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Wen, K. A.
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Cheng, Y. T.
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Chen, J. Y.
The first standard CMOS IC foundry flow is presented for the monolithic integration of MEMS sensor, analog readout circuit and wafer level capping on standard 0.18um 1P6M technology. The sensor and circuit parts are fabricated at first on the same 8 '' substrate using a standard 0.18um 1P6M CMOS process. The sensor part is then micromachined and released by a foundry-based post-CMOS DRIE process followed by wafer level capping. The test vehicle for the proposed integration flow contains a single-axial accelerometer, analog readout circuit with input common-mode feedback and QFN64 package. The measurement results show that the whole system can have 206mV/g of sensitivity and output noise is less than 250 mu g/root Hz. The proposed methodology has led a promising way for integrating MEMS, IC and package in a conventional IC foundry manufacturing flow.
Temperature-dependent yield effects on composite beams used in CMOS MEMS
(2013-03-01)
Kuo, F. Y.
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Chang, C. S.
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Liu, Y. S.
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Wen, K. A.
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Fan, L. S.
This paper presents an experimentally verified analytical model of temperature-dependent yield effects on the curvatures of composite beam structures used in complementary metal-oxide semiconductor microelectromechanical systems (CMOS MEMS). The temperature-dependent effects on composite beam curvatures of a thermal process can be predicted by extracting key parameters from the measured curvatures of a limited number of CMOS MEMS composite-layer combinations. The effects due to thermal history in MEMS packaging, which change the characteristics of beam curvatures due to material yield, are further analyzed. The models are verified with measured results from beam structures fabricated by an application-specific integrated circuit-compatible 0.18 mu m 1P6M CMOS MEMS process using a white light interferometer. These models can be applied in electronic design automation tools to provide good prediction of temperature-dependent properties related to CMOS MEMS beam curvature, such as sensing capacitance, for monolithic sensor system on chip design.
THE DESIGN AND IMPLEMENTATION OF A GARBAGE TRUCK FLEET MANAGEMENT SYSTEM
(2016-05)
Chen, C. H.
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Yang, Y. T.
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Chang, C. S.
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Hsieh, C. M.
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Kuan, T. S.
In recent years, the improvement of cloud computing and mobile computing techniques has led to the availability of a variety of mobile applications (\'apps\') in the app store. For instance, a garbage truck app that can provide the immediate location of a garbage truck, the location of collection points, and forecasted arrival times of garbage trucks would be useful for mobile users. Since the power consumption of apps on mobile devices if of concern to mobile users, an optimised power-saving mechanism for updating messages, which is based on location information, for a proposed garbage truck fleet management system (GTFMS) is proposed and implemented in this paper. The GTFMS is a three-component system that includes the on-board units on garbage trucks, a fleet management system, and a garbage truck app. In this study, an arrival time forecasting method is designed and implemented in the fleet management system, so that the garbage truck app can retrieve the forecasted arrival time via web services. A message updating event is then triggered that reports the location of garbage truck and the forecasted arrival time. In experiments conducted on case studies, the results showed that the mean accuracy of predicted arrival time by the proposed method is about 81.45 per cent. As for power consumption, the cost of traditional mobile apps is 2,880 times that of the mechanism proposed in this study. Consequently, the GTFMS can provide the precise forecasted arrival time of garbage trucks to mobile users, while consuming less power.