Browsing by Author "Wu, Yu-Chun"

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Angle-of-Arrival (AOA) Visible Light Positioning (VLP) System Using Solar Cells With Third-Order Regression and Ridge Regression Algorithms
(2020-06-01)
Hong, Chong-You
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Wu, Yu-Chun
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Liu, Yang
;
Chow, Chi-Wai
;
Yeh, Chien-Hung
We put forward and demonstrate a angle-of-arrival (AOA) based visible-light-positioning (VLP) system using quadrant-solar-cell (QSC) and third-order ridge regression machine learning (RRML) to improve the positioning accuracy.
CHIMNEY-ENHANCED DESIGN APPLIED ON THE THERMAL MANAGEMENT OF LED VEHICLE HEADLAMP
(2016)
Lin, Sheam-Chyun
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Chen, Yu-Cheng
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Wu, Yu-Chun
;
Yen, Hung-Cheng
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機械工程學系
LED vehicle headlamp consists of several high-power LEDs and thermal module inside an enclosed space, and locates near the high-temperature engine compartment. Certainly, these factors results in a challenging task on the thermal management of headlamp. Obviously, the temperature stratification inside this bounded region is an unfavorable phenomenon for the natural-convection thermal module. This study utilizes the chimney effect to achieve a more uniform temperature distribution and thus enhance the heat-dissipation ability. Firstly, an enclosed space is selected for executing the parametric study on the chimney geometry. Several effective alternatives are obtained and verified via both numerical and experimental means on the chimney design. Also, a significant 4.6 degrees C reduction on LED junction temperature is attained on the best chimney-enhanced module. Then, these guidelines are applied to a commercial LED headlamp. Consequently, a range of 3.8 similar to 4.6 degrees C decrease on LEDs is found for this innovative chimney thermal module.
CMOS camera based visible light communication (VLC) using grayscale value distribution and machine learning algorithm
(2020-01-20)
Hsu, Ke-Ling
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Wu, Yu-Chun
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Chuang, Yu-Cheng
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Chow, Chi-Wai
;
Liu, Yang
We demonstrate a visible light communication (VLC) system using light emitting diode (LED) backlight display panel and mobile-phone complementary-metal-oxide-semiconductor (CMOS) camera. The panel is primarily used for displaying advertisements. By modulating its backlight, dynamic contents (i.e. secondary information) can be transmitted wirelessly to users based on rolling shutter effect (RSE) of the CMOS camera. As different display content will be displayed on the panel, the VLC performance is significantly limited if the noise-ratio (NR) is too high. Here, we propose and demonstrate a CMOS RSE pattern demodulation scheme using grayscale value distribution (GVD) and machine learning algorithm (MLA) to significantly enhance the demodulation. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Complex Columnar Hexagonal Polymorphism in Supramolecular Assemblies of a Semifluorinated Electron-Accepting Naphthalene Bisimide
(2015-01-21)
Wu, Yu-Chun
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Leowanawat, Pawaret
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Sun, Hao-Jan
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Partridge, Benjamin E.
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Peterca, Mihai
Simple synthetic methods for a strongly electron-accepting naphthalene bisimide (NBI) derivative functionalized with a new environmentally friendly chiral racemic semifluorinated alkyl group and with AB(3) minidendrons containing the same semifluorinated group are reported. The semifluorinated dendron was attached to the imide groups of the NBI via one, two, and three (m = 1, 2, 3) methylenic units. The NBI-containing semifluorinated groups and the dendronized NBI with m = 1 and 2 self-organize into lamellar crystals. The dendronized NBI with m = 3 self-assembles into an unprecedentedly complex and ordered column that self-organizes in a columnar hexagonal periodic array. This array undergoes a continuous transition to a columnar hexagonal superlattice that does not display a first-order phase transition during analysis by differential scanning calorimetry at heating and cooling rates of 10 and 1 degrees C/min. These complex columnar hexagonal periodic arrays with intramolecular order could be elucidated only by a combination of powder and fiber X-ray diffraction studies and solid-state NMR experiments. The lamellar crystals self-organized from m = 1 and the two highly ordered columnar hexagonal periodic arrays of m = 3 are assembled via thermodynamically controlled processes. Since strongly electron-accepting derivatives are of great interest to replace fullerene acceptors in organic photovoltaics and for other supramolecular electronic materials, the multitechnique structural analysis methodology elaborated here must be taken into consideration in all related studies.
Crystal Structure and Molecular Packing Behavior of Poly(2,3-diphenyl-1,4-phenylenevinylene) Derivatives Containing Alkyl Side-Chains
(2013-01-08)
Ren, Xiang-Kui
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Wu, Yu-Chun
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Wang, Shao-Jie
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Jiang, Shi-Dong
;
Zheng, Jun-Feng
Phase behavior and crystal structure of a series of poly(2,3-diphenyl-5-alkyl-p-phenylenevinylene) (denoted as DPn-PPV, where n represents the carbon number of the alkyl side-chain, n = 6, 8, 10, 12) were studied using differential scanning calorimetry, one- and two-dimensional (1D and 2D) wide-angle X-ray diffraction (WAXD), and selected area electron diffraction (SAED). The experimental results reveal that DPn-PPV exhibits one crystalline phase at low temperatures. On the basis of 2D WAXD and SAED patterns obtained from the oriented samples, the crystal structures are determined to be orthorhombic for DP6-PPV and monoclinic for DP8-PPV, DP10-PPV, and DP12-PPV. To account for the unusually large unit cell dimensions, we propose that the unit cell of DPn-PPV contains 4 chains (8 chemical repeat units). The complex crystal structure can be attributed to the longitudinal and transverse offsets between the neighboring chains, which shall be mainly due to the requirement of minimizing the steric hindrance caused by the attached pendent groups and maximizing the pi-pi interaction between the chains. The molecular packing scheme was simulated by using Cerius(2) software, of which the result agrees with the experimental data. The polarized UV-vis absorption and polarized solid-state photoluminescence (PL) property of these polymers was also investigated. The PL spectra indicated that the light emitted from the oriented film was preferentially polarized parallel to the shear direction, implying that DPn-PPV may potentially be useful in linearly polarized luminescence devices.
Development of lattice-inserted 5-Fluorouracil-hydroxyapatite nanoparticles as a chemotherapeutic delivery system
(2015-10-01)
Tseng, Ching-Li
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Chen, Jung-Chih
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Wu, Yu-Chun
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Fang, Hsu-Wei
;
Lin, Feng-Huei
Developing an effective vehicle for cancer treatment, hydroxyapatite nanoparticles were fabricated for drug delivery. When 5-Fluorouracil, a major chemoagent, is combined with hydroxyapatite nanocarriers by interclay insertion, the modified hydroxyapatite nanoparticles have superior lysosomal degradation profiles, which could be leveraged as controlled drug release. The decomposition of the hydroxyapatite nanocarriers facilitates the release of 5-Fluorouracil into the cytoplasm causing cell death. Hydroxyapatite nanoparticles with/without 5-Fluorouracil were synthesized and analyzed in this study. Their crystallization properties and chemical composition were examined by X-ray diffraction and Fourier transforms infrared spectroscopy. The 5-Fluorouracil release rate was determined by UV spectroscopy. The biocompatibility of hydroxyapatite-5-Fluorouracil extraction solution was assessed using 3T3 cells via a WST-8 assay. The effect of hydroxyapatite-5-Fluorouracil particles which directly work on the human lung adenocarcinoma (A549) cells was evaluated by a lactate dehydrogenase assay via contact cultivation. A 5-Fluorouracil-absorbed hydroxyapatite particles were also tested. Overall, hydroxyapatite-5-Fluorouracils were prepared using a co-precipitation method wherein 5-Fluorouracil was intercalated in the hydroxyapatite lattice as determined by X-ray diffraction. Energy dispersive scanning examination showed the 5-Fluorouracil content was higher in hydroxyapatite-5-Fluorouracil than in a prepared absorption formulation. With 5-Fluorouracil insertion in the lattice, the widths of the a and c axial constants of the hydroxyapatite crystal increased. The extraction solution of hydroxyapatite-5-Fluorouracil was nontoxic to 3T3 cells, in which 5-Fluorouracil was not released in a neutral phosphate buffer solution. In contrast, at a lower pH value (2.5), 5-Fluorouracil was released by the acidic decomposition of hydroxyapatite. Finally, the results of the lactate dehydrogenase assay revealed that 5-Fluorouracil-hydroxyapatite was highly toxic to A549 cells through direct culture, this phenomenon may result from lysosomal decomposition of particles causing 5-Fluorouracil releasing. The pH-responsive hydroxyapatite-5-Fluorouracil nanoparticles have the potential to be part of a selective drug-delivery system in chemotherapy for cancer treatment.
miRTarBase update 2018: a resource for experimentally validated microRNA-target interactions
(2018-01-04)
Chou, Chih-Hung
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Shrestha, Sirjana
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Yang, Chi-Dung
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Chang, Nai-Wen
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Lin, Yu-Ling
MicroRNAs (miRNAs) are small non-coding RNAs of similar to 22 nucleotides that are involved in negative regulation of mRNA at the post-transcriptional level. Previously, we developed miRTarBase which provides information about experimentally validated miRNA-target interactions (MTIs). Here, we describe an updated database containing 422 517 curated MTIs from 4076 miRNAs and 23 054 target genes collected from over 8500 articles. The number of MTIs curated by strong evidence has increased similar to 1.4-fold since the last update in 2016. In this updated version, target sites validated by reporter assay that are available in the literature can be downloaded. The target site sequence can extract new features for analysis via a machine learning approach which can help to evaluate the performance of miRNA-target prediction tools. Furthermore, different ways of browsing enhance user browsing specific MTIs. With these improvements, miRTarBase serves as more comprehensively annotated, experimentally validated miRNA-target interactions databases in the field of miRNA related research. miRTarBase is available at http://miRTarBase.mbc.nctu.edu.tw/.
Porphyrin-diindenothieno[2,3-b]thiophene alternating copolymerua blue-light harvester in ternary-blend polymer solar cells
(2012-12-15)
Wu, Yu-Chun
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Chao, Yi-Hsiang
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Wang, Chien-Lung
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Wu, Chun-Ta
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Hsu, Chain-Shu
Porphyrin, despite chosen by Nature as light harvesting units, hasn't revealed its full potentials as a structural unit in porphyrin-incorporated polymers (PPors). A novel PPor was synthesized to investigate the origins of the low performances of PPor-based polymer solar cells (PSCs). The polymer features broad absorption in the blue-light region, because the diindenothieno[2,3-b]thiophene (DITT) unit extended the conjugation in the polymer backbone. PPor-DITT/PC71BM based PSCs have a high Voc (0.79 V). Their low Jsc and fill factor (FF) were attributed to the un-optimized morphology, as indicated by the photoluminescence quenching and atomic force microscopy (AFM) experiments. Using PPor-DITT as a blue-light harvesting dopant in an amorphous host leverage the strong 400550 nm absorption of PPor-DITT and circumvent the difficulties in reaching optimized morphology in the PPor/PCBM thin films. An addition of 2 wt % of PPor-DITT in ternary-blend PSCs resulted in a 10 % increase of external quantum efficiency (EQE) in the blue-light region. However, in a crystalline host, the dopant decreased the crystallinity of the host and led to large drops in FF and power conversion efficiencies (PCEs). The study provides an alternative route and expands the application of PPors in PSCs as a blue-light harvester in ternary-blend PSCs using amorphous polymers as host. (C) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Preservation of Photoluminescence Efficiency in the Ordered phases of Poly(2,3-diphenyl-1,4-phenylenevinylene) via Disturbing the Intermolecular pi-pi Interactions with Dendritic Aliphatic Side Chains
(2012-06-12)
Wu, Yu-Chun
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Ren, Xiang-Kui
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Chen, Er-Qiang
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Lee, Hsun-Mei
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Duvail, Jean-Luc
To understand the relation between the solid-state phase structures and the photophysical properties of poly(2,3-diphenyl-1,4-phenylenevinylene) (DP-PPV) derivatives, three DP-PPV derivatives, P1-P3, were designed, synthesized via Gilch polymerization and characterized. Among the polymers, PI is a reported highly emissive poly(2,3-diphenyl-5-hexyl-p-phenylenevinylene), and P2 and P3 are novel DP-PPV derivatives, which are purposely designed to bear hydrophobic and hydrophilic Percec-type dendrons as side chains. The bulkiness and hydrophobic hydrophilic natures of the side chains show strong effects on photophysical properties of the polymers. The solutions and as-casted films of P1-F3 all show remarkably high photoluminescence (PL) efficiency (Phi(PL)) (>80% in chloroform solution, and >63% for the as-casted films). However, Phi(PL) of P1 and P3 decrease significantly to 30% after cooled their polymer melts to room temperature. Through the phase behavior analysis by differential scanning calorimetry (DSC), and phase structure analysis by wide-angle X-ray diffraction (WAXD), the decrease of Phi(PL) can be elucidated and attributed to the ordering of the solid-state structures of PI and P3. To our surprise, Phi(PL) of P2 is preserved even in an ordered solid-state phase, and it is insensitive to the structural ordering. Structural analysis of P2 revealed that the aliphatic dendritic side chains of P2 effectively disturbing the intermolecular pi-pi interactions among the conjugated backbones, which allows the preservation of Phi(PL) in the environment with ordered packing of DP-PPV molecules. The results of time-resolved PL decay experiments also confirmed that P2 possesses long-lived decay time because of excitons confined more effectively for emissive relaxation.
Svnthesis and ODW-electrical prperties of dendron-containing poly(2,3-diphenyl-1,4-phenylenevinylene) derivatives
(2007-08-01)
Yang, Sheng-Hsiung
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Chen, Shiang-Ying
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Wu, Yu-Chun
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Hsu, Chain-Shu
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應用化學系
A new series of poly(2,3-diphenyl-1,4-phenylenevinylene) derivatives containing dendritic side groups were synthesized. Different generations of dendrons were integrated on the pendant phenyl ring to investigate their effect on optical and electrical properties of final polymers. Homopolymers can not be obtained via the Gilch polymerization because of sterically bulky dendrons. By controlling the feed ratio of different monomers during polymerization, dendron-containing copolymers with high molecular weights were obtained. The UV-vis absorption and photoluminescent spectra of the thin films are pretty close; however, quantum efficiency is significantly enhanced with increasing the generation of dendrons. The electrochemical analysis reveals that hole-injection is also improved by increasing dendritic generation. Double-layer light-emitting devices with the configuration of ITO/PEDOT:PSS/polymer/Ca/Al were fabricated. High generation dendrons bring benefit of improved device performance. (c) 2007 Wiley Periodicals, Inc.
Visible light positioning (VLP) system using low-cost organic photovoltaic cell (OPVC) for low illumination environments
(2020-08-31)
Hong, Chong-You
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Wu, Yu-Chun
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Lin, Yu-Hsiang
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Liu, Yang
;
Chow, Chi-Wai
We propose and demonstrate a received-signal-strength (RSS) based visible light positioning (VLP) system using a low-cost organic photovoltaic cell (OPVC) receiver (Rx). The OPVC is a passive device without the need of external power supply. It could detect VLC signal and harvest energy. Our developed OPVC has a high power conversion efficiency (PCE) of 9.8%. The VLP system can be operated at a low illumination of 130 lux. The regression machine learning (MIL) algorithm is used to enhance the positioning accuracy. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement