Browsing by Author "Chieng, Wei-Hua"

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All GaN-on-Si High Power Module Design and Performance Evaluation
(2013)
Cheng, Stone
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Wang, Chieh-An
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Chou, Po-Chien
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Chieng, Wei-Hua
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Chang, Edward Yi
This paper presents a 270-V, 56-A GaN power module with three AlN substrates are prepared for the module. Each substrate is composed of three parallel connected GaN chips which incorporates six 2-A AlGaN/GaN-on-Si high electron mobility transistors (HEMTs) cells. The substrate layout inside the module is designed to reduce package parasitic. The devices are wire-bonded in parallel connection to increase the power rating. The packaged GaN HEMTs exhibit the pulsed drain current of 0.435 A/mm. Both DC and pulsed current-voltage (ID-VDS) characteristics are measured for different connection and sizes of devices, at various of power densities, pulse lengths, and duty factors. The other static parameters like threshold voltage and leakage currents were extracted to show how these parameters would scale as the devices are paralleled. Performance of multiple chip GaN power module package is studied. Experimental results demonstrated the ability to parallel nine GaN HEMTs die together and to verify the current sharing during the dynamic switching to attain high-current capacities.
Analyzing the perception of Chinese melodic imagery and its application to automated composition
(2016-07)
Huang, Chih-Fang
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Lian, Yu-Shian
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Nien, Wei-Po
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Chieng, Wei-Hua
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機械工程學系
This study investigated the influence of two music elements, mode and rhythm, on melodic imagery. By modulating different parameters of mode and rhythm, this study produced various melody samples. Kansei engineering was adopted as a research method for designing the experimental process. A set of music assessment rules was established by regularizing the existing modes and rhythms and analyzing and comparing their differences. The results were applied to automated composition in order to develop a comprehensive automated composition system. Before the hearing experiment, 39 adjective pairs were selected for the survey of melodic imagery by reviewing literature and engaging in discussions with experts. A Markov chain was adopted for analyzing the current modal music to establish a Markov switching table for the Chinese pentatonic scale, and metrical complexity was used for generating rhythms. Finally, 30 music samples were produced using the automated composition system by applying the various combinations of modes and rhythms. The hearing experiment was conducted on 35 participants for examining their perception of melodic imagery. Item analysis and a reliability test were performed on the experimental data for eliminating invalid samples and items. Thus, 14 adjective pairs with a Cronbach\'s alpha of 0.887 were obtained, indicating favorable reliability. In addition, this study involved conducting factor analysis and extracting three imagery factors, namely passionate-apathetic, beautiful-ugly, and romantic-rigid. Subsequently, multivariate analysis of variance was conducted in this study for determining the relationship between modes and metrical complexity and the 14 adjective pairs, and the estimated means were calculated. Multidimensional scaling was adopted for producing a two-dimensional perceptual map for the construction of a database. The experimental results of this study showed that modes and rhythms in music can effectively help musicians or computer composition systems compose melodies that create various perceptual imageries.
Design and Analysis of Spatial Parallel Manipulator for Dual Axis Solar Tracking
(2014-06-01)
Jeng, Shyr-Long
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Lue, Bin-Han
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Chieng, Wei-Hua
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機械工程學系
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Department of Mechanical Engineering
This work develops a solar tracker that is configured in a parallel manipulator structure for maximum power generation. The conventional solar tracker with a serial gimbaled structure is simply supported by the central pivot in the module frame of the solar panel, and the structural deformation of the frame causes the PV cells on the side of the panel to be frequently out of focus. Accordingly, the power efficiency of the PV can fall rapidly for each degree of misalignment with respect to the sun. This work introduces a spatial parallel mechanism to increase the rigidity of the solar tracker structure and thereby improve its power efficiency. The prototype mechanism that is demonstrated in this work can feasibly track the sun completely from sunrise to sunset at latitude of 23.7 N degrees. Different tracking postures against the solar hour at the summer solstice, spring equinox, and winter solstice are animated.
Design and development of an IoT-based web application for an intelligent remote SCADA system
(2018-01-01)
Kao, Kuang-Chi
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Chieng, Wei-Hua
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Jeng, Shyr-Long
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機械工程學系
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Department of Mechanical Engineering
This paper presents a design of an intelligent remote electrical power supervisory control and data acquisition (SCADA) system based on the Internet of Things (IoT), with Internet Information Services (IIS) for setting up web servers, an ASP.NET model-view- controller (MVC) for establishing a remote electrical power monitoring and control system by using responsive web design (RWD), and a Microsoft SQL Server as the database. With the web browser connected to the Internet, the sensing data is sent to the client by using the TCP/IP protocol, which supports mobile devices with different screen sizes. The users can provide instructions immediately without being present to check the conditions, which considerably reduces labor and time costs. The developed system incorporates a remote measuring function by using a wireless sensor network and utilizes a visual interface to make the human-machine interface (HMI) more instinctive. Moreover, it contains an analog input/output and a basic digital input/output that can be applied to a motor driver and an inverter for integration with a remote SCADA system based on IoT, and thus achieve efficient power management.
Enhanced lateral heat dissipation packaging structure for GaN HEMTs on Si substrate
(2013-03-01)
Cheng, Stone
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Chou, Po-Chien
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Chieng, Wei-Hua
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Chang, E. Y.
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機械工程學系
This work presents a technology for packaging AlGaN/GaN high electron mobility transistors (HEMTs) on a Si substrate. The GaN HEMTs are attached to a V-groove copper base and mounted on a TO-3P leadframe. The various thermal paths from the GaN gate junction to the case are carried out for heat dissipation by spreading to protective coating; transferring through the bond wires; spreading in the lateral device structure through the adhesive layer, and vertical heat spreading of silicon chip bottom. Thermal characterization showed a thermal resistance of 13.72 degrees C/W from the device to the TO-3P package. Experimental tests of a 30 mm gate-periphery single chip packaged in a 5 x 3 mm V-groove Cu base with a 100 V drain bias showed power dissipation of 22 W. (c) 2012 Elsevier Ltd. All rights reserved.
Estimating Speed Using a Side-Looking Single-Radar Vehicle Detector
(2014-04-01)
Jeng, Shyr-Long
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Chieng, Wei-Hua
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Lu, Hsiang-Pin
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機械工程學系
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Department of Mechanical Engineering
This paper presents a side-looking single-beam microwave vehicle detector (VD) system for estimation of per-vehicle speed and length. The proposed VD system is equipped with a 2-D range Doppler frequency-modulated continuous-wave (FMCW) radar using a squint angle. The associated Fourier processor uses an inverse synthetic aperture radar (ISAR) algorithm to extract range and speed data for each vehicle using a single-beam FMCW radar. The simulation and experimental results show accurate estimations of vehicle speed and length. The measurement errors of speed and length were approximately +/- 4 km/h and +/- 1 m, respectively. The proposed method has excellent detection capability for small moving targets, such as bikes and pedestrians, at speeds down to 5 km/h. A commercial 10.6-GHz radar with signal processing modifications was used in the experiments.
Estimation of single-tone signal frequency with special reference to a frequency-modulated continuous wave system
(2012-03-01)
Huang, Chih-Fang
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Lu, Hsiang-Pin
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Chieng, Wei-Hua
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機械工程學系
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Department of Mechanical Engineering
Estimating the frequency of a single-tone signal is a common problem in radar applications, such as frequency-modulated continuous wave radar. This study presents a frequency estimation algorithm called the gradient search method using the derivative of discrete Fourier transform on the received signal samples. The analytical boundaries of the proposed method for different signal-to-noise ratios under the two conditions, with the rectangular window and with the Hann window, are derived. This study also compares the most appropriate algorithms available in the literature, including chirp-Z transform and other advanced methods. Simulation and experimental results show that the proposed algorithm provides superior performance to previous methods.
Five-Axis Slerp for Tool-Orientation Planning in a Five-Axis CNC Machine
(2018-12-01)
Yan, Chang Dau
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Chieng, Wei-Hua
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Jeng, Shyr-Long
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機械工程學系
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Department of Mechanical Engineering
The quaternion spherical linear interpolation method (slerp), which many researchers have adopted for numerical control, is inadequate for tool-axisorientation planning in general five-axis computer numerical control machines. This paper explains why the quaternion slerp method fails to achieve constant rotational speed. The machining quality is degraded when the quaternion slerp method is used in five-axis machining. To compensate for this failure, this paper proposes a solution for tool-axis-orientation planning, the five-axis slerp method, which generates steady angular velocity of the interpolation curve.
Gallium Nitride Electrical Characteristics Extraction and Uniformity Sorting
(2015-01-01)
Jeng, Shyr-Long
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Wu, Chih-Chiang
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Chieng, Wei-Hua
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機械工程學系
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Department of Mechanical Engineering
This study examined the output electrical characteristics-current-voltage (I-V) output, threshold voltage, and parasitic capacitance-of novel gallium nitride (GaN) power transistors. Experimental measurements revealed that both enhanced-and depletion-mode GaN field-effect transistors (FETs) containing different components of identical specifications yielded varied turn-off impedance; hence, the FET quality was inconsistent. Establishing standardized electrical measurements can provide necessary information for designers, and measuring transistor electrical characteristics establishes its equivalent-circuit model for circuit simulations. Moreover, high power output requires multiple parallel power transistors, and sorting the difference between similar electrical characteristics is critical in a power system. An isolated gate driver detection method is proposed for sorting the uniformity from the option of the turn-off characteristic. In addition, an equivalent-circuit model for GaN FETs is established on the basis of the measured electrical characteristics and verified experimentally.
In Celebration of Professor Wen-Hwa Chen's 70th Birthday
(2018-12-01)
Chen, Cha'o-Kuang
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Lin, Zone-Ching
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Chieng, Wei-Hua
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機械工程學系
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Department of Mechanical Engineering
Least Squares Approach to Odometry based on Multiple Optical Mouse Sensors
(2010)
Wu, Ping-Lin
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Jeng, Shyr-Long
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Chieng, Wei-Hua
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機械工程學系
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Department of Mechanical Engineering
This work describes an optical measuring device that comprises multiple laser mouse sensors to estimate 3-DOF planar motion. The linear least squares (LLS) method and nonlinear least squares (NLS) method are adopted to estimate the positions in this over-determined system. Two circular trajectories - non-orientated and self-orientated - are employed to evaluate the feasibility of the proposed device. The results are presented and validated by simulations and experimentally. For a circular trajectory with self-orientation, the estimated positions of device determined using the NLS method are associated with apparently smaller positional errors than those calculated using the LLS method. The noise at the sensor outputs has a large impact on the estimate of position. The analysis is essential to examining the error sources and increasing the accuracy of odometric measurement.
Measuring virtual experience in a three-dimensional virtual reality interactive simulator environment: a structural equation modeling approach
(2014-09-01)
Cheng, Li-Keng
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Chieng, Ming-Hua
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Chieng, Wei-Hua
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機械工程學系
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經營管理研究所
With the rapid development of the VR market, virtual experience has increasingly been the object of study in recent years. A growing number of studies have reported the positive effect that virtual experience can have on a user's mood and loyalty. However, few studies have investigated the influence of the mechanism of virtual experience on users' mood and loyalty. To compensate for this research gap, this study aims to evaluate consumers' virtual experience by examining the flow state in a virtual environment. A total of 368 valid questionnaires were collected, and a structural equation modeling approach was employed in the data analysis. The study reveals that forming flow involves many factors: the intrinsic characteristics of the mediated environment, the consumer's assumptions and perceptions prior to entering the flow state, the stage at which the customer enters the flow state, and the consequences of the flow experience.
Measuring virtual experience in a three-dimensional virtual reality interactive simulator environment: a structural equation modeling approach
(2014-09-01)
Cheng, Li-Keng
;
Chieng, Ming-Hua
;
Chieng, Wei-Hua
;
機械工程學系
;
經營管理研究所
With the rapid development of the VR market, virtual experience has increasingly been the object of study in recent years. A growing number of studies have reported the positive effect that virtual experience can have on a user\'s mood and loyalty. However, few studies have investigated the influence of the mechanism of virtual experience on users\' mood and loyalty. To compensate for this research gap, this study aims to evaluate consumers\' virtual experience by examining the flow state in a virtual environment. A total of 368 valid questionnaires were collected, and a structural equation modeling approach was employed in the data analysis. The study reveals that forming flow involves many factors: the intrinsic characteristics of the mediated environment, the consumer\'s assumptions and perceptions prior to entering the flow state, the stage at which the customer enters the flow state, and the consequences of the flow experience.
Motion behavior of triangular waveform excitation input in an operating impact drive mechanism
(2011-03-01)
Yang, Chia-Feng
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Jeng, Shyr-Long
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Chieng, Wei-Hua
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機械工程學系
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Department of Mechanical Engineering
Stable stepping motion from mechanical excitation of a piezoelectric device is generated using the impact drive mechanism (IDM) based on various triangular waveforms exerted by the counter mass speed. However, stick-slip behavior originating from the contact friction between the movable part and the guide surface poses an obstacle for precise modeling. Therefore, this work presents a concise impulse model for mechanism control of stepping motion behavior. The proposed impulse model incorporates the duty ratio and input frequency of the triangular waveform of counter mass relative displacement as the system input and outputs the estimated step size and the behavior of the stepping motion. An enhanced version of the dynamic model and our experimental results validate the efficacy of the proposed model. An adequate design and control of IDM motion is highly promising for use in nano-scale positioning. (C) 2010 Elsevier B.V. All rights reserved.
Multi-Level Balanced Isolated Floating Difference Amplifier
(2008-11-01)
Tung, Yung-Cheng
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Jeng, Shyr-Long
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Chieng, Wei-Hua
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機械工程學系
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Department of Mechanical Engineering
An innovative amplifier is proposed for applications involving high capacitive load and large voltage output swing, such as piezoelectric (PZT) actuator drivers. This amplifier is configured in a multi-level arrangement with floating amplifiers, yielding a high voltage gain as a sum of all individual gains from its operational amplifiers. The merits of such an amplifier also include a wide bandwidth and high potential power. Experiments using a six-level arrangement demonstrate a 100 kHz bandwidth with +/-200 V output swing for different capacitive loadings.
Optimal motion cueing for 5-DOF motion simulations via a 3-DOF motion simulator
(2009-01-01)
Chang, Yang-Hung
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Liao, Chung-Shu
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Chieng, Wei-Hua
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機械工程學系
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Department of Mechanical Engineering
This study presents a novel motion-cueing strategy, which is applied to a motion simulator with three rotational degrees of freedom (DOF) to perform the roll, pitch, yaw, surge, and sway motions by using an online optimization algorithm. The weighting functions are adaptively tuned in each step, and the optimal Euler angles are obtained analytically. This motion-cueing algorithm is efficient since it requires no recursive search on the optimal solution. Experiments demonstrating the validity of the 5-DOF motion simulation are also included. (C) 2008 Elsevier Ltd. All rights reserved.
OPTIMIZATION SETTING OF DYNAMICS PARAMETERS FOR AN ATV SIMULATOR
(2011)
Wu, Ping-Lin
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Liao, Chung-Shu
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Chieng, Wei-Hua
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機械工程學系
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Department of Mechanical Engineering
Driving all-terrain vehicles (ATVs) is a popular recreational activity. However, driving on an unpaved road poses risks even to an experienced ATV driver. In this work, a six-degree of-freedom ATV motion simulator is designed. A motion platform, which provides a safe and comfortable environment for drivers to develop their skill over an extended period, is used to simulate the dynamics of a passive ATV suspension. The proposed simulator provides a virtual ATV driving environment that includes rough terrains that drivers may feel uncomfortable with even in the simulated environment. Importantly, the simulator optimizes the dynamic parameters of the suspension system, enabling ATV drivers to experience the driving activity more comfortably yet realistically. A comparison between simulation results and experimental results indicates that the simulator has high adaptability.
Outrigger Force Measure for Mobile Crane Safety Based on Linear Programming Optimization#
(2010)
Jeng, Shyr-Long
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Yang, Chia-Feng
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Chieng, Wei-Hua
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機械工程學系
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Department of Mechanical Engineering
This work presents a linear programming simplex method for evaluating allowable reaction forces of multiple outriggers with stability constraints. Minimum/maximum pruning approach is adopted to increase the computational efficiency of assessing the outrigger forces when a mobile crane is kept level by the supports of four outriggers. Determining the outrigger forces is an effective means of preventing a mobile crane from tipping over or outrigger failures. Two indices, i.e., moment-index and force-index, which quantify the tendency of tip-over behavior of mobile cranes and examine the bearing capacity of outrigger, are introduced to improve the safety measures. The safety hoist criteria of two mobile crane types equipped with different outriggers are analyzed to demonstrate the feasibility of the proposed scheme. An intelligent anti-upset device that utilizes the outrigger-based stability measures and selectively suppresses critical steering commands in real time is implemented to ensure safe crane operations.
Simplified Methodology for Ride Comfort Assessment Based on Wheel/Rail Contact Geometry Synthesis
(2017-08-01)
Wu, Ye-Ee
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Chien, Ming-Hung
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Liao, Kuen-Laing
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Lin, Zone-Ching
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Chieng, Wei-Hua
This article proposes a simplified methodology for ride comfort assessment based on wheel/rail contact geometry synthesis without Complicated measurements or simulations. A mechanism drawing with particular reference to G(1) continuity is used to describe a reliable wheel/rail profile and to derive a profile equation to be applied in contact geometry synthesis. The proposed method is used to explore all possible positions of contact between a wheel and rail on each side of the track. Based on synthesis results, moving and fixed centrodes of carbody motion are proposed. The degree of smoothness of the moving and fixed centrodes is applied to define the range of the sweet spot in terms of the wheel/rail tread area. In this study, contact between the Shinkansen wheel and UIC60 and JIS60 rails is investigated as a case study. The results show that the Shinkansen wheel matches the UIC60 rail more effectively because it has a wider range of contact sweet spots than the JIS60 rail when rolling stock is running on a curved track. Finally, the Shinkansen wheel profile and each rail profile equation are applied in simulation software of a vehicle track system with different wheel/rail matchings to verify that contact geometry synthesis can be used to assess ride comfort. A dynamic simulation program, whose parameters are adjusted to fit experimental values, is used to compare the results. The results show that both the vertical and lateral vibration acceleration responses of a carbody with the Shinkansen wheel in contact with the UIC60 rail are stable and lower than those for the JIS60 rail. Furthermore, the UIC60 rail provides a better degree of ride comfort to passengers when matched with the Shinkansen wheel. Therefore, contact geometry synthesis of wheel/rail contact can be used to assess the movement behavior of rolling stock and derive a simplified index of ride comfort.
The controllable ball joint mechanism
(2006-12-01)
Tung, Yung Cheng
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Chieng, Wei-Hua
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Ho, ShrWai
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機械工程學系
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Department of Mechanical Engineering
A controllable ball joint mechanism with three rotational degrees of freedom is proposed in this paper. The mechanism is composed of three bevel gears, one of which rotates with respect to a fixed frame and the others rotate with respect to individual floating frames. The output is the resultant motion of the differential motions by the motors that rotates the bevel gears at the fixed frame and the floating frames. The mechanism is capable of a large rotation, and the structure is potentially compact. The necessary inverse and forward kinematic analyses as well as the derivation of kinematic singularity are provided according to the kinematical equivalent structure described in this paper.