Browsing by Author "Chang, Hsiu-Cheng"

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A facile dedoping approach for effectively tuning thermoelectricity and acidity of PEDOT:PSS films
(2014-03-01)
Tsai, Tsung-Che
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Chang, Hsiu-Cheng
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Chen, Chun-Hua
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Huang, Yi-Chia
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Whang, Wha-Tzong
A facile approach namely controlling the pH level of 5 wt% dimethyl sulfoxide (DMSO) doped poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) solution with sodium hydroxide (NaOH) was utilized for the first time in successfully optimizing the thermoelectric conversion efficiency of PEDOT:PSS films. The largely varied Seebeck coefficients and electrical conductivities of the pH controlled PEDOT:PSS films which could thus construct a beneficial curve for locating the optimized power factor are clearly shown from the significant changes of the carrier concentration via the dedoping of PEDOT. The correlation between pH value and carrier concentration as well as the power factor is experimentally found with numerical description covering a full pH range. The applied technique and the resulting optimized thermoelectric properties and possible bio-compatibility not only provide a fundamental understanding of the thermoelectric conducting polymers but widely disclose a variety of potential applications in the future. (C) 2014 Elsevier B. V. All rights reserved.
A Facile Surface Treatment Utilizing Binary Mixtures of Ammonium Salts and Polar Solvents for Multiply Enhancing Thermoelectric PEDOT: PSS Films
(2014-12-01)
Tsai, Tsung-Che
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Chen, Tsung-Han
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Chang, Hsiu-Cheng
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Chen, Chun-Hua
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Huang, Yi-Chia
A Two level Mode Decision Algorithm for H.264 High Profile Intra Encoding
(2012)
Chang, Cheng-Yen
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Chien, Cheng-An
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Chang, Hsiu-Cheng
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Chen, Jia-Wei
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Guo, Jiun-In
A two level mode decision algorithm considering edge information for H.264 high profile intra encoding is proposed to reduce the computational complexity. In level one mode decision, the edge information is used to decide the appropriate intra coding block size according to the observations that a smooth macroblock usually chooses the large intra coding block size, and that a complex macroblock usually chooses the small one. In level two mode decision, we use the correlation between adjacent blocks to decide the appropriate prediction modes. The propose method achieves 34%similar to 59% reduction of computational complexity when compared to JM14 and the PSNR only drops 0.09 db in averag.
A VIEW SCALABLE MULTI-VIEW VIDEO DECODER SYSTEM
(2013-01-01)
Lee, Jui-Sheng
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Miao, Yuan-Hsiang
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Chien, Cheng-An
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Chang, Hsiu-Cheng
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Guo, Jiun-In
This paper presents a view scalable multi-view video decoder system that integrates multiple decoder cores into the proposed system to decode multi-view video and achieve parallel decoding with high view scalability. We manage the firmware for video bit-stream partition and design an arbitration mechanism to balance the work load among decoder cores with a 4KB two-level cache architecture for inter-view/inter-frame prediction data reusing. With such a flexible architecture, the proposed system can reach 1.8 times performance improvement with two decoding cores and 3.5 times with four decoding cores. Based on the proposed system, users only need to adjust the number of decoder cores and set the firmware parameters for different system applications. This feature also benefits to adopting 3D IC packaging or implementation to exploit high bandwidth DRAM access. The proposed view scalable multi-view video decoder system is able to decode multiple-view HD video in real time.
A VIEW SCALABLE MULTI-VIEW VIDEO DECODER SYSTEM
(2013)
Lee, Jui-Sheng
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Miao, Yuan-Hsiang
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Chien, Cheng-An
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Chang, Hsiu-Cheng
;
Guo, Jiun-In
This paper presents a view scalable multi-view video decoder system that integrates multiple decoder cores into the proposed system to decode multi-view video and achieve parallel decoding with high view scalability. We manage the firmware for video bit-stream partition and design an arbitration mechanism to balance the work load among decoder cores with a 4KB two-level cache architecture for inter-view/inter-frame prediction data reusing. With such a flexible architecture, the proposed system can reach 1.8 times performance improvement with two decoding cores and 3.5 times with four decoding cores. Based on the proposed system, users only need to adjust the number of decoder cores and set the firmware parameters for different system applications. This feature also benefits to adopting 3D IC packaging or implementation to exploit high bandwidth DRAM access. The proposed view scalable multi-view video decoder system is able to decode multiple-view HD video in real time.
An Adaboost-based Two-level Moving Object Detection Architecture with Dynamic ROI Allocation
(2014-01-01)
Lee, Jui-Sheng
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Chang, Hsiu-Cheng
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Guo, Jiun-In
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交大名義發表
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National Chiao Tung University
This paper presents a hardware architecture to detect moving objects based on Adaboost algorithm [1] with Haar-like feature for driving safety. According to the complex appearances of pedestrians and motorcyclists at closer distance, the proposed design supports 12-level scaling for detection window size with dynamic ROI allocation. The stride mode results in highly complex 12-level window size scaling. So a two-level fast search method for decreasing hardware cost while preserving 93.6% detection rate is proposed. The proposed design comprises of 173K gates and 35.7Kbytes SRAM. The maximum working frequency is 200MHz that is able to process VGA@31fps and QVGA@107fps input video. With the detection window sizes scaled from 14x28 to 40x80, the proposed design supports detection at a distance as far as 40 meters.
An Inter-frame/Inter-view Cache Architecture Design for Multi-view Video Decoders
(2012)
Lee, Jui-Sheng
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Wang, Sheng-Han
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Chou, Chih-Tai
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Chien, Cheng-An
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Chang, Hsiu-Cheng
In this paper we propose a low-bandwidth two-level inter-frame/ inter-view cache architecture for a view scalable multi-view video decoder, which adopts two decoder cores to decode multi-view videos in parallel. The first level L1 cache is developed for the single video decoder core, which is able to reduce 60% bandwidth in doing inter-frame prediction in average. Moreover, we develop the second level L2 cache architecture to reuse the same reference data for doing interview prediction among different decoder cores, which can further reduce 35% bandwidth. By adopting the proposed two-level cache architecture for doing inter-frame/ inter-view prediction, we can reduce 80% bandwidth through a view scalable multi-view video decoder implementation, which achieves real-time HD1080 dual-view video decoding.
Enhanced thermoelectricity of three-dimensionally mesostructured BixSb2-xTe3 nanoassemblies: from micro-scaled open gaps to isolated sealed mesopores
(2017-03-07)
Chen, Tsung-Han
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Lin, Ping-Yu
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Chang, Hsiu-Cheng
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Chen, Chun-Hua
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材料科學與工程學系
We describe an innovative interfacial design concept and nanostructuring of novel BixSb2-xTe3 (BST) nanoassembled films comprising unique air-solid interfaces from micro-scaled open gaps to isolated sealed mesopores, and high-quality solid-solid ones including the coherent grain boundaries and specific twins, utilizing pulsed laser deposition (PLD), for potentially activating multiple thermoelectric enhancing mechanisms. The unusual mesopore embedded BST films exhibit the highest power factor of similar to 33 mu W cm(-1) K-2, which is comparable to or higher than the previously reported values for BST, and the corresponding relatively low thermal diffusivity in contrast to that for dense pore-less BST films evidently reveals the crucial role of the three-dimensionally and densely arranged air-solid interfaces in significantly arising the phonon scattering.
Great enhancements in the thermoelectric power factor of BiSbTe nanostructured films with well-ordered interfaces
(2013)
Chang, Hsiu-Cheng
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Chen, Chun-Hua
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Kuo, Yung-Kang
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材料科學與工程學系
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Department of Materials Science and Engineering
An innovative concept of twin-enhanced thermoelectricity was proposed to fundamentally resolve the high electrical resistance while not degrading the phonon scattering of the thermoelectric nanoassemblies. Under this frame, a variety of highly oriented and twinned bismuth antimony telluride (BixSb2-xTe3) nanocrystals were successfully fabricated by a large-area pulsed-laser deposition (PLD) technique on insulated silicon substrates at various deposition temperatures. The significant presence of the nonbasal- and basal-plane twins across the hexagonal BiSbTe nanocrystals, which were experimentally and systematically observed for the first time, evidently contributes to the unusually high electrical conductivity of similar to 2700 S cm(-1) and the power factor of similar to 25 mu W cm(-1) K-2 as well as the relatively low thermal conductivity of similar to 1.1 W m(-1) K-1 found in these nanostructured films.
High Efficiency Data Access System Architecture for Deblocking Filter Supporting Multiple Video Coding Standards
(2012-05-01)
Chien, Cheng-An
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Jian, Guo-An
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Chang, Hsiu-Cheng
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Chen, Kuan-Hung
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Guo, Jiun-In
"This paper presents an efficient VLSI architecture of in-loop deblocking filter (ILF) with high efficiency data access system for supporting multiple video coding standards including H. 264 BP/MP/HP, SVC, MVC, AVS, and VC-1. Advanced standards, such as H. 264 MP/HP, SVC, and MVC, adopt Macro Block Adaptive Frame Field (MBAFF) to enhance coding efficiency which results in the performance bottleneck of deblocking filter due to complex data access requirement. This design challenge has not been discussed in previous works according to our best knowledge. Therefore, we develop a Prediction Data Management (PDM) to manage the input prediction data order of deblocking filter for different coding types (like frame/field) and multiple standards. We also design an extended output frame buffer module to solve the system bus architecture restriction (like 1K boundary and burst length) and achieve high efficiency data access by using MB-based scan order. By using these techniques, we can solve the data accessing design challenge and reduce 67% bus latency. After being implemented by using 90 nm CMOS technology, the proposed work can achieve real-time performance requirement of QFHD (3840x2160@30fps) when operated at 156MHz at the cost of 50.6K gates and 2.4K bytes local memory. The maximum operating frequency of the proposed design, i.e. 370MHz, is higher than the required real-time operating frequency so that voltage scaling may be adopted to reduce power consumption."
Numerical and model predictions of the thermal conductivity of bismuth telluride nanoprism-assembled films
(2015-08-01)
Hou, Yi-Cheng
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Huang, Mei-Jiau
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Chuang, Pi-Yueh
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Chang, Hsiu-Cheng
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Chen, Chun-Hua
This research aims at understanding the heat transfer phenomenon in the Bi2Te3 nanoprism-assembled films. For obtaining the associated effective thermal conductivity, the effective-medium-approximation (EMA) models existing in literature were examined and properly modified for prediction and Monte-Carlo numerical experiments based on unstructured grids were performed for confirmation. Cross-plane and in-plane thermal conductivities were both explored. For model predictions, the characteristic grain size of the nanoprisms is defined as either the phonon mean free path purely due to the grain boundary scattering (i.e. excluding the intrinsic scattering) or the averaged hydraulic diameter. A combination of a non-dilute 2D EMA model with the triple bond percolation theory turns out to be the best model for predicting the in-plane thermal conductivity. On the other hand, the evaluation of the cross-plane thermal conductivity by treating the nanoprisms as thermal conductors connected in parallel is satisfactory. The investigation shows that in addition to porosity, the scattering at the grain boundaries plays a dominant role in reducing the heat transfer in the direction perpendicular to the boundaries: the in-plane thermal conductivity is therefore much smaller than the cross-plane one. (C) 2015 Elsevier Ltd. All rights reserved.
Self-assembled bismuth telluride films with well-aligned zero- to three-dimensional nanoblocks for thermoelectric applications
(2011)
Chang, Hsiu-Cheng
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Chen, Chun-Hua
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材料科學與工程學系
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Department of Materials Science and Engineering
The dimension and size of the building blocks as well as the preferential orientation, geometry and regularity of their assemblies are the most important key factors for fabricating thermoelectric materials with a high figure-of-merit (ZT) which is governed by the efficiencies in transporting electrical and thermal energies along the measurement direction. A one-step and large-area growth approach has been successfully developed employing pulsed laser deposition (PLD) for producing physically self-assembled and well-aligned Bi(2)Te(3) nanostructures on SiO(2)/Si substrates without pre-built templates or catalysts. The precisely parameter-controlled growth provides four highly reproducible and significant Bi(2)Te(3) assemblies, comprising 0-dimensional (0-D) nanoparticles, 1-D nanorods, 2-D nanoflakes, and 3-D nanocanyons, respectively exhibiting an overall (006), (015), (110), and (006) preferential orientation normal to the substrate surface. The nanoparticle assisted crystal growth is proposed, mainly involving the condensation of the plasma species in the gas phase at higher ambient pressures and the following diffusion and reorganization of the deposited nanoparticle atoms on the substrates. The well-aligned 0-D to 3-D Bi(2)Te(3) nanostructures show more excellent in-plane power factors than most of the randomly aligned Bi(2)Te(3) nanostructures at room temperature mainly due to significantly reducing inter resistance. The thermoelectric properties of these well-aligned Bi(2)Te(3) nanostructures are comparable to any other intrinsic Bi(2)Te(3) nanostructures that have ever been reported. The present data are valuable for further improving and designing advanced thermoelectric materials and confirm that precise control of nanostructural aggregation is an effective strategy for enhancing the thermoelectric performance.
Smart assembling of multi-scaled functional interfaces in thermoelectric Ga2Te3/Te hetero-nanocomposites
(2014-01-01)
Chang, Hsiu-Cheng
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Chiang, Ming-Hsiu
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Tsai, Tsung-Che
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Chen, Tsung-Han
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Whang, Wha-Tzong
We describe an innovative concept and facile approach in fabricating laterally assembled Ga2Te3/Te binary nanocomposite films, which comprise two-dimensional quasi-periodic Ga2Te3 nanoassemblies surrounded by interlocking highly-conductive Te single crystals for comprehensively establishing subnanoto micro-scaled multi-style versatile interfaces. The distinct Ga2Te3/Te nanocomposite film exhibits a power factor that is about 60 times higher than the reported conventional Ga2Te3 and Te materials, mainly due to the 2- to 3-order improved electrical conductivity and the comparable Seebeck coefficient.
Superassembling of Bi2Te3 hierarchical nanostructures for enhanced thermoelectric performance
(2015-01-01)
Chang, Hsiu-Cheng
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Chen, Tsung-Han
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Whang, Wha-Tzong
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Chen, Chun-Hua
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材料科學與工程學系
We describe a facile and one-step pulsed laser deposition (PLD) technique that was utilized for the first time to systematically fabricate a series of innovative Bi2Te3 superassembly-on-epitaxy bi-layer nanostructures, by uniquely coupling the upper self-assembled well-ordered Bi2Te3 hierarchical nanostructures with unusually high surface-and interface-to-volume ratios and a highly electrical conductive epitaxial bottom thin layer on insulated SiO2/Si substrates, as an emerging new class of the most advanced thermoelectric nanomaterials. The optimized power factor of the present superassembly-on-epitaxy films is one to three orders of magnitude higher than that of most Bi2Te3 nanoassemblies defined as the assemblies of nanocrystals, evidently proving the significance and potential of the present new concept and the resulting thermoelectric nanomaterials.
Widely variable Seebeck coefficient and enhanced thermoelectric power of PEDOT:PSS films by blending thermal decomposable ammonium formate
(2011-12-01)
Tsai, Tsung-Che
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Chang, Hsiu-Cheng
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Chen, Chun-Hua
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Whang, Wha-Tzong
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材料科學與工程學系
The doping effects of thermal decomposable ammonium formate (AF) from 5 to 50 wt.% on the electrical conductivity, Seebeck coefficient, and microstructures of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films have been investigated for the first time for modern thermoelectric applications. It has been found that the Seebeck coefficient can be effectively tuned in a very wide range by varying the AF doping concentration, where a maximum value of 436.3 mu V/K was obtained, i.e., similar to 40 times higher in magnitude than the pure PEDOT:PSS films prepared with same processes. The greatly enhanced Seebeck coefficient is considered to be the result of reducing the carrier concentration, as evidenced by the Hall measurement. In addition, AF also plays an important role in the formation of the closed or open pores and channels within the films for phonon scattering, as can be clearly observed in the SEM images. The present work provides a new procedure to effectively control the Seebeck coefficient as well as the microstructures of PEDOT:PSS polymer by a simple blending approach with suitable thermal steps, which has not previously been reported. (C) 2011 Elsevier B.V. All rights reserved.