Browsing by Author "Chang, C. -H."

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A Method for the Non-invasive Assessment of Chest Wall Growth in Pectus Excavatum Patients
(2010-03-01)
Chang, P. -Y.
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Chang, C. -H.
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Lai, J. -Y.
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Chen, J. -C.
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Perng, D. -B.
Introduction: Various scales and measurement methods including X-rays and computed tomography (CT) have been used to quantify the degree of deformity in pectus excavatum. This study describes a non-invasive method for recording the deviation of the anterior chest wall (ACW) in pectus excavatum (PE) patients. Data obtained using this non-invasive method were compared with CT data. Materials and Methods: Twenty-one patients treated at our institutions between June 2008 and February 2009 were enrolled in this study. All patients underwent CT and thermal plastic strip measurement. A thermal plastic strip was positioned and taped to the supine patient's ACW at the skin level from the posterior axillary line, over the depressed sternum, to the contralateral posterior axillary line and used to create a casting of the ACW. Results: The funnel index (FI) was defined as the width of the ACW divided by its height; the concave index (CI) was defined as the breadth of the depressed area of the funnel chest divided by its depth. Pearson's correlation coefficient was used to compare the FI and CI obtained with the thermal plastic strip method and with CT; measurements obtained with both methods were found to correlate well (FI: r(2) = 0.965; CI: r(2) = 0.947). Conclusions: The thermal plastic strip measurement method provides a two-dimensional record of the shape of the anterior chest wall. The measurement can be repeated, does not involve the patient being exposed to radiation, and offers a good longitudinal assessment of chest wall growth in PE patients.
Applications of stochastic lumping analysis to fluctuations in systems and structure biology
(2017-07-01)
Deng, D. -M.
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Lu, Y. -T.
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Chang, C. -H.
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物理研究所
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Institute of Physics
Asynchronous Rational Harmonic Mode-Locked Er-Doped Fiber Soliton Laser
(2010)
Chang, C. -H.
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Jyu, S. -S.
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Hsiang, W. -W.
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Lai, Y.
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光電工程學系
An asynchronous rational harmonic mode-locked fiber laser (ARHML) is demonstrated experimentally. Through the asynchronous mode-locking mechanism, the output pulse train has a wider optical spectrum and very uniform amplitudes with the un-wanted harmonic frequency components highly suppressed. (C) 2009 Optical Society of America
Boosted Gain of the Differential Amplifier Using the Second Gate of the Dual-Gate a-IGZO TFTs
(2012-12-01)
Tai, Y. -H.
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Chiu, H. -L.
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Chou, L. -S.
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Chang, C. -H.
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光電工程學系
A dual-gate amorphous InGaZnO4 (a-IGZO) thin-film transistor (TFT) has two gate electrodes. The primary gate electrode is at the bottom, and the other is on the top. The drain current of the TFT can be controlled by both the bottom and top gates. This phenomenon provides great flexibility for the circuit design. In this letter, we propose the differential amplifier circuit using the top gate of the dual-gate a-IGZO TFT as an input for positive feedback to boost the gain. It is experimentally verified that the gain of the differential amplifier circuit is increased three times larger than those without the feedback loop.
Design of X-band complementary metal-oxide semiconductor-based frequency-modulation continuous-wave sensor
(2009-12-01)
Chang, C. -H.
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Wang, S.
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Wu, H. -S.
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Liang, E. -C.
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Liu, A. -S.
This study presents an X-band complementary metal-oxide semiconductor-based frequency-modulation continuous-wave (FMCW) sensor system for transportation management. The proposed sensor system has two antennas, one to transmit signals and the other to receive them. The complete radio frequency (RF) transceiver is based on standard 0.18 mm one-poly six-metal (1P6M) CMOS technology with a chip area of 1.68 mm x 1.6 mm. Two planar leaky-mode antenna arrays with a gain of 18 dB are also designed. Experimental results indicate that the isolation between two antenna arrays that are 5.0 mm apart exceeds 42.0 dB at 10.5 GHz. The prototype of the FMCW sensor system is used in the range measurement of multiple lanes for the transportation management system (TMS). The major contribution of this study is that it integrates a 0.18 mm CMOS transceiver and antenna arrays into an FMCW RF front end, and employs an IF amplifier and a digital signal processor to demonstrate that the beat frequencies are linear. Measurements made in field tests agree closely with the simulation results.
Fully integrated bio-chip with high sensitivity for electrochemical sensing application
(2019-04-18)
Chen, W. -H.
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Chang, C. -H.
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Shih, H. -Y.
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Chiu, T. -W.
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Kuo, C. -N.
This Letter presents a fully integrated bio-system with the property of high sensitivity for electrochemical detection, which can intrinsically measure electrochemical characteristics with cyclic voltammetry. In normal circumstances, ultra-low electrolytes exist in tissue solution, which is difficult to accurately detect the oxidation/reduction signals, limited by the innate circuit and liquid noise. Hence, the conventional topology of the potentiostat circuit is improved and proposed in this Letter to remove the required analogue-to-digital converter (ADC). The overall operational mechanism of the potentiostat behaves like a single-slope ADC, which achieves a compact, easily implemented, and low-noise design. Additionally, the effective capacitance of potentiostat and liquid resistance make an RC integration to further suppress out-of-band noise, thereby enabling the low-electrolyte detection and improving detecting sensitivity. To simulate the low-electrolyte environment, only 0.01 M (M = mol/l) phosphate buffered saline background solution is used and required to demonstrate its feasibility of the concept. The measured results show the sensor chip with high sensitivity to sense resistive variation of electrochemical action in low electrolytes.
Improved optical transmission and current matching of a triple-junction solar cell utilizing sub-wavelength structures
(2010-09-13)
Chiu, M. -Y.
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Chang, C. -H.
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Tsai, M. -A.
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Chang, F. -Y.
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Yu, Peichen
Sub-wavelength antireflective structures are fabricated on a silicon nitride passivation layer of a Ga(0.5)In(0.5)P/GaAs/Ge triple-junction solar cell using polystyrene nanosphere lithography followed by anisotropic etching. The fabricated structures enhance optical transmission in the ultraviolet wavelength range, compared to a conventional single-layer antireflective coating (ARC). The transmission improvement contributes to an enhanced photocurrent, which is also verified by the external quantum efficiency characterization of the fabricated solar cells. Under one-sun illumination, the short-circuit current of a cell with sub-wavelength structures is enhanced by 46.1% and 3.4% due to much improved optical transmission and current matching, compared to cells without an ARC and with a conventional SiN(x) ARC, respectively. Further optimizations of the sub-wavelength structures including the periodicity and etching depth are conducted by performing comprehensive calculations based on a rigorous couple-wave analysis method. (C) 2010 Optical Society of America
MULTIBAND FOLDED LOOP ANTENNA FOR SMART PHONES
(2010)
Chiu, C. -W.
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Chang, C. -H.
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Chi, Y. -J.
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
This paper presents a multiband folded loop antenna for smart phone applications. The proposed antenna with a symmetric loop pattern generates four resonance modes in the design bands. The current distributions of the excited resonance modes are analyzed to confirm the mode characteristic. Using a pair of tuning elements near the feed port, the impedance bandwidth is broadened to cover GSM850/GSM900/DCS/PCS/UMTS bands. This research performed simulation by a high frequency structure simulator (HFSS) to optimally design the antenna, and a practical structure was constructed to test. The current study measured the antenna parameters including reflection coefficient, radiation characteristics, peak gain, and radiation efficiency to validate the proposed antenna.
UWB Gilbert downconverter with lumped-distributed phase-inverter rat-race coupler based on Chebyshev band-broadening technique
(2011-07-21)
Wei, H. -J.
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Meng, C.
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Chang, C. -H.
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Huang, G. -W.
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電子工程學系及電子研究所
A broadband Gilbert downconverter with a miniature phase-inverter rat-race coupler is demonstrated using 0.35 mu m SiGe BiCMOS technology. By lumped-distributed and band-broadening techniques, a large shrinkage ratio with wide bandwidth of Chebyshev response can be simultaneously attained in the spiral-shape coplanar-stripline phase-inverter rat-race coupler. The area of the demonstrated lumped-distributed phase-inverter rat-race coupler is 0.65 x 0.65 mm(2) and the experimental bandwidth ranging from 2.5 to 12.5 GHz is large enough to cover the UWB bandwidth. As a result, a broadband Gilbert downconverter with the proposed coupler achieves a conversion gain of 11-12 dB, IP(1dB) of -11 dBm, IIP(3) of -1 dBm and noise figure of 16 dB from 3 to 11 GHz.