Browsing by Author "Chen, Cheng-Chang"

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A Study of T-S Model-Based SMC Scheme With Application to Robot Control
(2008-11-01)
Liang, Yew-Wen
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Xu, Sheng-Dong
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Liaw, Der-Cherng
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Chen, Cheng-Chang
;
電控工程研究所
In light of the remarkable benefits and numerous applications of the Takagi-Sugeno (T-S) fuzzy system modeling method and the sliding mode control (SMC) technique, this paper aims to study the design of robust controllers for a set of second-order systems using a combination of these two approaches. The combined scheme is shown to have the merits of both approaches. It alleviates not only the online computational burden by using the T-S fuzzy system model to approximate the original nonlinear one (since most of the system parameters of the T-S model can be computed offline) but also preserves the advantages of rapid response and robustness characteristic of the classic SMC schemes. Moreover, the combined scheme does not need to online compute any nonlinear term of the original dynamics, and the increase in the number of fuzzy rules does not create extra online computational burdens for the scheme. The proposed analytical results are also applied to the control of a two-link robot manipulator and compared with the results using classic SMC design. Simulation results demonstrate the benefits of the proposed scheme.
Dimmable sunlight-like organic light emitting diodes with ultra-high color rendering index
(2016-05)
Wu, Jin-Han
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Chi, Chien-An
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Chiang, Chang-Lin
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Chen, Guan-Yu
;
Lin, Yi-Ping
We propose novel dimmable sunlight-like white organic light-emitting diodes that were fabricated using three luminophores to form an emitting spectrum similar to black body radiation at 2250 K with ultra-high color rendering index (CRI) value of 91, which nearly remained the constant at various luminance values ranging from 100 to more than 2500 cd/m(2) at Commission Internationale de l\'Eclairage chromaticity coordinates of (0.51, 0.41). Introducing charge modification layers suppressed the energy transfer between the emitting material layers and increased the probability of carrier recombination. Moreover, we reveal that covering long-wavelength ranges played a vital role in achieving high CRI values; the CRI values of a spectrum artificially shifted toward a long-wavelength direction (from 610 to 620 nm) remained constant, whereas those of a spectrum shifted toward a short-wavelength direction (from 610 to 600 nm) dropped to 79. (C) 2016 Elsevier B.V. All rights reserved.
Enabling Lambertian-Like Warm White Organic Light-Emitting Diodes with a Yellow Phosphor Embedded Flexible Film
(2014-01-01)
Chen, Cheng-Chang
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Lin, Huang-Yu
;
Li, Cheng-Hung
;
Wu, Jin-Han
;
Tu, Zong-Yi
We demonstrate in this report a new constructive method of fabricating white organic light-emitting devices (OLEDs) with a flexible plastic film embedded with yellow phosphor. The flexible film is composed of polydimethylsiloxane (PDMS) and fabricated by using spin coating followed by peeling technology. From the results, the resultant electroluminescent spectrum shows the white OLED to have chromatic coordinates of 0.38 and 0.54 and correlated color temperature of 4200 K. The warm white OLED exhibits the yield of 10.3 cd/A and the luminous power efficiency of 5.4 lm/W at a luminance of 1000 cd/m(2). A desirable Lambertian-like far-field pattern is detected from the white OLEDs with the yellow phosphor containing PDMS film. This method is simple, reproducible, and cost-effective, proving to be a highly feasible approach to realize white OLED.
Enabling Lambertian-Like Warm White Organic Light-Emitting Diodes with a Yellow Phosphor Embedded Flexible Film
(2014-01-01)
Chen, Cheng-Chang
;
Lin, Huang-Yu
;
Li, Cheng-Hung
;
Wu, Jin-Han
;
Tu, Zong-Yi
We demonstrate in this report a new constructive method of fabricating white organic light-emitting devices (OLEDs) with a flexible plastic film embedded with yellow phosphor. The flexible film is composed of polydimethylsiloxane (PDMS) and fabricated by using spin coating followed by peeling technology. From the results, the resultant electroluminescent spectrum shows the white OLED to have chromatic coordinates of 0.38 and 0.54 and correlated color temperature of 4200 K. The warm white OLED exhibits the yield of 10.3 cd/A and the luminous power efficiency of 5.4 lm/W at a luminance of 1000 cd/m(2). A desirable Lambertian-like far-field pattern is detected from the white OLEDs with the yellow phosphor containing PDMS film. This method is simple, reproducible, and cost-effective, proving to be a highly feasible approach to realize white OLED.
Large Area of Ultraviolet GaN-Based Photonic Quasicrystal Laser
(2012-04-01)
Chen, Cheng-Chang
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Chiu, Ching-Hsueh
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Tu, Po-Min
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Kuo, Ming-Yen
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Shih, M. H.
In this study, large-area GaN-based photonic quasicrystal (PQC) nanopillars were fabricated on an n-GaN substrate using the nanoimprint lithography (NIL) technique. Under optical pumping condition, a high lasing action from the GaN photonic quasicrystals was observed. The lasing wavelength is at 366nm with a low threshold power density of 0.009 kW/cm(2). To confirm the band-edge lasing mode, the finite-element method (FEM) was used to perform the simulation for the 12-fold symmetry photonic quasicrystal lattices. (C) 2012 The Japan Society of Applied Physics
Large-area ultraviolet GaN-based photonic quasicrystal laser with high-efficiency green color emission of semipolar {10-11} In0.3Ga0.7N/GaN multiple quantum wells
(2013-01-07)
Chen, Cheng-Chang
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Chiu, Ching-Hsueh
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Chang, Shih-Pang
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Shih, M. H.
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Kuo, Ming-Yen
In this study, a multi-color emission was observed from the large-area GaN-based photonic quasicrystal (PQC) nanopillar laser. The GaN PQC nanostructure was fabricated on an n-GaN layer by using nanoimprint lithographic technology. The regrown InGaN/GaN multiple quantum wells (MQWs) formed a nanopyramid structure on top of the PQC nanopillars. A lasing action was observed at ultraviolet wavelengths with a low threshold power density of 24 mJ/cm(2), and a green color emission from InGaN/GaN MQWs was also achieved simultaneously. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4775373]
Lasing in metal-coated GaN nanostripe at room temperature
(2011-03-28)
Wang, Yow-Gwo
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Chen, Cheng-Chang
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Chiu, Ching-Hsueh
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Kuo, Ming-Yen
;
Shih, M. H.
This study demonstrated a metal-coated GaN nanostripe laser operable at room temperature. The ultraviolet lasing mode was observed at a wavelength of approximately 370 nm with a low threshold power density of 0.042 kW/cm(2). The lasing mode of the metal-coated nanostripe was characterized using finite-element method simulation. The results showed the significance of metal coatings in this nanocavity structure for lasing at room temperature. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3572023]
Light Emission Enhancement of GaN-Based Photonic Crystal With Ultraviolet AlN/AlGaN Distributed Bragg Reflector
(2010-11-15)
Chen, Cheng-Chang
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Chen, Jun-Rong
;
Yang, Yi-Chun
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Shih, M. -H.
;
Kuo, Hao-Chung
In this study, we demonstrated two-dimensional (2-D) photonic crystal band-edge coupling operation in the ultraviolet wavelength range. The light extraction enhancement was obtained from the photonic crystal structure with an ultraviolet AlN/AlGaN distributed Bragg reflector (UVDBR). The DBR provides a high reflectivity of 85% with 15-nm stopband width. A fivefold enhancement in photoluminescence emission was also achieved compared with the emission from the unpatterned area on the same sample at 374 nm wavelength. We also study the photonic crystal band-edge coupling with finite-difference time-domain and plane-wave expansion methods.
Light Enhancement of Silicon-Nanocrystal-Embedded SiO(x) Film on Silicon-on-Insulator Substrate
(2011-04-01)
Chen, Cheng-Chang
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Lin, Yung-Hsaing
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Shih, M. H.
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Lin, Gong-Ru
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Kuo, Hao-Chung
We reported the light enhancement from a silicon-nanocrystal-embedded SiO(x) film on a silicon-on-insulator (SOI) substrate in the visible light range. The light emission from the annealed SiO(x) film is one order stronger than the emission from a nonannealed SiO(x) film. Compared with the SiO(x) film on a Si substrate, two-fold enhancement in light emission from the SiO(x) film on a SOI substrate was also observed. The enhancement was attributed to better vertical confinement of optical field in the SiO(x) film on a SOI substrate. (C) 2011 The Japan Society of Applied Physics
Light Enhancement of Silicon-Nanocrystal-Embedded SiOx Film on Silicon-on-Insulator Substrate
(2011-04-01)
Chen, Cheng-Chang
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Lin, Yung-Hsaing
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Shih, M. H.
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Lin, Gong-Ru
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Kuo, Hao-Chung
We reported the light enhancement from a silicon-nanocrystal-embedded SiOx film on a silicon-on-insulator (SOI) substrate in the visible light range. The light emission from the annealed SiOx film is one order stronger than the emission from a nonannealed SiOx film. Compared with the SiOx film on a Si substrate, two-fold enhancement in light emission from the SiOx film on a SOI substrate was also observed. The enhancement was attributed to better vertical confinement of optical field in the SiOx film on a SOI substrate. (C) 2011 The Japan Society of Applied Physics
Room temperature lasing with high group index in metal-coated GaN nanoring
(2011-12-19)
Wang, Yow-Gwo
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Chang, Shu-Wei
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Chen, Cheng-Chang
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Chiu, Ching-Hsueh
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Kuo, Ming-Yen
The room temperature lasing action from a metal-coated GaN nanoring cavity was observed by optical pumping. The GaN nanoring is 7 mu m in diameter and 400 nm in width. The quality factor of the cavity is approximately 860 with a threshold power density of 37.5 mJ/cm(2). Such a device performance was attributed to the combination of metal-coated nanocavity with whispering-gallery modes. Moreover, the group index extracted from the experiment was 5.99 and was verified with calculations and analyses of the lasing modes as well as their characteristics. The study showed a promising way to further improve the performance of metal-coated nanolasers. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3671648]
Significant color space blue-shift of green OLED emitter with sustaining lifetime and substantial efficiency enhancement
(2017-08-28)
Li, Jung-Yu
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Chen, Shih-Pu
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Siao, Huei-Jhen
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Wu, Jin-Han
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Chen, Guan-Yu
In this study, we demonstrate that by embedding a plasmonic coupling metal layer beneath the active layer of an organic light-emitting diode, the resultant device is capable of inducing significant blue shifts in CIE color space coordinates of emitting light from the green emitting material without compromising the lifetime of the parent material. The implemented device consists of multilayers of organic emitting materials sandwiched by two thin metal layers to form a metal-dielectric-metal (MDM) cavity-like structure. The original green emission with CIE coordinates of (0.22, 0.56) was significantly color space blue-shifted to CIE coordinates of (0.10, 0.53). The MDM device exhibits an efficiency of 62 cd/A at a luminance of 1000 cd/m(2), which represents a two-fold enhancement of current efficiency. Moreover, the spectral peak intensity is 4.3 times higher than that in a conventional device, which is much higher than that expected for an optical microcavity model, suggesting that the Purcell effect resulting from the coupling of surface plasmon waves may contribute to the extra enhancement of emission intensity. Published by AIP Publishing.
Significant color space blue-shift of green OLED emitter with sustaining lifetime and substantial efficiency enhancement (vol 111, 093301, 2017)
(2017-09-11)
Li, Jung-Yu
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Chen, Shih-Pu
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Siao, Huei-Jhen
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Wu, Jin-Han
;
Chen, Guan-Yu
Tunable Light Emission from GaN-Based Photonic Crystal with Ultraviolet AlN/AlGaN Distributed Bragg Reflector
(2011-04-01)
Chen, Cheng-Chang
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Chiu, Ching-Hsueh
;
Yang, Yi-Chun
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Shih, M. H.
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Chen, Jun-Rong
In this paper, the characteristics of GaN-based two-dimensional (2D) photonic crystal bandedge coupling operation with an ultraviolet AlN/AlGaN distributed Bragg reflector (DBR) have been investigated and analyzed. The 25-pair AlN/Al(0.2)GaN(0.8) DBR shows a high reflectivity of 85% at 375nm with the stop-band width of 15nm. A strong light emission was observed from GaN photonic crystals within high reflectivity region of DBR. The emission wavelength can be also manipulated by varying the radius to lattice constant ratio. The photonic crystal bandedge mode was also characterized with three-dimensional plane-wave expansion (PWE) and finite-difference time-domain (FDTD) simulation. (C) 2011 The Japan Society of Applied Physics
Ultraviolet GaN-based microdisk laser with AlN/AlGaN distributed Bragg reflector
(2010-04-12)
Chen, Cheng-Chang
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Shih, M. H.
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Yang, Yi-Chun
;
Kuo, Hao-Chung
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光電工程學系
We demonstrated a 4.7 mu m GaN-based microdisk laser with 25-pair AlN/AlGaN distributed Bragg reflector in ultraviolet range without undercut or deeply-etching procedures. The distributed Bragg reflector provides a high reflectivity of 85%, and selects lasing mode around 375 nm wavelength. Under optical pumping conditions, the lasing action was observed with a low threshold power density of 0.03 kW/cm(2). We also characterized the whispering gallery mode profiles of the microdisk with finite-different time-domain simulation.