Browsing by Author "Wang, Cheng-Hung"

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An emotion recognition mechanism based on the combination of mutual information and semantic clues
(2012-03-01)
Lin, Hao-Chiang Koong
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Hsieh, Min-Chai
;
Loh, Li-Chen
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Wang, Cheng-Hung
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應用藝術研究所
Recently, text-based emotion recognition has become more and more highly regarded. After exploring the related research, we have found that: (1) In the semantics-based solution, the newly emerging compound words cannot be handled. (2) In the statistics-based solution, the emotional values are computed only via the linear text clues; it lacks syntactic and semantic structural information. Therefore, in our effort to overcome the two concerns above, in the system presented here we construct an extensible lexicon and use semantic clues to analyze the sentences. In this work, we collected the sentences posted to the Plurk website as our corpus. The emoticons are classified into four types based on Thayer\'s 2-D Model which is composed of valence (positive/negative emotions) and arousal (the strength of emotions). The system will preprocess the sentence to eliminate the useless information, and then transform it to an emotion lexicon. Additionally, this research analyzes three kinds of semantic clues: negation, transition, and coordinating conjunctions. The final emotion is decided by SVM and the merging algorithm proposed in this work. Moreover, the recognition rate is promoted from 40.3 to 68.15% after the emotion lexicon is improved, and the semantic structural information is applied. The experimental results show that the work is promising.
Field effect of in-plane gates with different gap sizes on the Fermi level tuning of graphene channels
(2014-05-05)
Lin, Meng-Yu
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Chen, Yen-Hao
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Wang, Cheng-Hung
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Su, Chen-Fung
;
Chang, Shu-Wei
Tuning of the Fermi level is investigated in graphene channels using two in-plane gates with significantly different-sized isolating gaps. While the n-type tuning was achievable in both schemes, the wide-gap device had an enhanced minimum drain current and less prominent current modulation than the narrow-gap device. In addition, further p-type tuning was not observed in the wide-gap device at negative gate biases. These phenomena indicated that both devices had distinct field-strength dependences and Fermi level tuning effects, which may be critical for the practical design of devices. (C) 2014 AIP Publishing LLC.
Passivated graphene transistors fabricated on a millimeter-sized single-crystal graphene film prepared with chemical vapor deposition
(2015-07-29)
Lin, Meng-Yu
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Wang, Cheng-Hung
;
Chang, Shu-Wei
;
Lee, Si-Chen
;
Lin, Shih-Yen
In this work, we first investigate the effects of partial pressures and flow rates of precursors on the single-crystal graphene growth using chemical vapor depositions on copper foils. These factors are shown to be critical to the growth rate, seeding density and size of graphene single crystals. The prepared graphene films in millimeter sizes are then bubbling transferred to silicon-dioxide/silicon substrates for high-mobility graphene transistor fabrications. After high-temperature annealing and hexamethyldisilazane passivation, the water attachment is removed from the graphene channel. The elimination of uncontrolled doping and enhancement of carrier mobility accompanied by these procedures indicate that they are promising for fabrications of graphene transistors.
Toward epitaxially grown two-dimensional crystal hetero-structures: Single and double MoS2/graphene hetero-structures by chemical vapor depositions
(2014-08-18)
Lin, Meng-Yu
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Chang, Chung-En
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Wang, Cheng-Hung
;
Su, Chen-Fung
;
Chen, Chi
Uniform large-size MoS2/graphene hetero-structures fabricated directly on sapphire substrates are demonstrated with layer-number controllability by chemical vapor deposition (CVD). The cross-sectional high-resolution transmission electron microscopy (HRTEM) images provide the direct evidences of layer numbers of MoS2/graphene hetero-structures. Photo-excited electron induced Fermi level shift of the graphene channel are observed on the single MoS2/graphene hetero-structure transistors. Furthermore, double hetero-structures of graphene/MoS2/graphene are achieved by CVD fabrication of graphene layers on top of the MoS2, as confirmed by the cross-sectional HRTEM. These results have paved the possibility of epitaxially grown multi-hetero-structures for practical applications. (C) 2014 AIP Publishing LLC.
Transferring-free and large-area graphitic carbon film growth by using molecular beam epitaxy at low growth temperature
(2015-09-01)
Lin, Meng-Yu
;
Wang, Cheng-Hung
;
Pao, Chun-Wei
;
Lin, Shih-Yen
;
顯示科技研究所
Graphitic carbon films prepared by using molecular beam epitaxy (MBE) on metal templates with different thicknesses deposited on SiO2/Si substrates are investigated in this paper. With thick Cu templates, only graphitic carbon flakes are obtained near the Cu grain boundaries at low growth temperatures on metal/SiO2 interfaces. By replacing the Cu templates with thin Ni templates, complete graphitic carbon films with superior crystalline quality is obtained at 600 degrees C on SiO2/Si substrates after removing the Ni templates. The enhanced attachment of the graphitic carbon film to the SiO2/Si substrates with reduced Ni thickness makes the approach a promising approach for transferring-free graphene preparation at low temperature by using MBE. (C) 2015 Elsevier B.V. All rights reserved.