Browsing by Issue Date, starting with "2013-06-07"

Now showing 1 - 20 of 31425

Resonant cavity-enhanced quantum-dot infrared photodetectors with sub-wavelength grating mirror
(2013-06-07)
Wang, Chi-Cheng
;
Lin, Sheng-Di
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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
We propose and simulate a device structure of resonant cavity-enhanced quantum-dot infrared photodetector (RCE-QDIP). The RCE-QDIP consists of a conventional n-i-n QDIP sandwiched by a bottom GaAs/Al2O3 distributed Bragg reflector and a top mirror of Ge/SiO2 sub-wavelength grating. Aiming for detecting mid-infrared at 8 mu m, the total thickness of the device is only similar to 7.7 mu m. According to our simulation, the external quantum efficiencies of RCE-QDIP could be as high as 59%-78% with the enhancement factors of 7-30, compared with a conventional QDIP. The proposed RCE-QDIP is highly feasible as the various fabrication parameters are considered. (C) 2013 AIP Publishing LLC.
On parallel complexity of analytic functions
(2013-06-10)
Yu, Fuxiang
;
Ko, Ker-I
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資訊工程學系
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Department of Computer Science
In this paper, we study the parallel complexity of analytic functions. We investigate the complexity of computing the derivatives, integrals, and zeros of NC or logarithmic-space computable analytic functions, where NC denotes the complexity class of sets acceptable by polynomial-size, polylogarithmic-depth, uniform Boolean circuits. It is shown that the derivatives and integrals of NC (or logarithmic-space) computable analytic functions remain NC (or, respectively, logarithmic-space) computable. We also study the problem of finding all zeros of an NC computable analytic function inside an NC computable Jordan curve, and show that, under a uniformity condition on the function values on the Jordan curve, all zeros can be found in NC. (c) 2013 Elsevier B.V. All rights reserved.
神經纖維之電極刺激方法及其系統
(2013-06-11)
蔡德明
;
李宜軒
本發明為一種神經纖維之電極刺激方法及其系統，方法包含下列步驟。利用接收單元接收聲音訊號；利用處理單元將聲音訊號分成複數個頻帶；藉由處理單元於各頻帶中取出頻譜峰值，並依據各頻譜峰值大小決定各頻帶的刺激順序；根據刺激順序和判斷規則，處理單元於複數個週期內選擇性地驅動複數個電極群組，以產生對應各頻帶之刺激訊號；藉由各刺激訊號以呈現出聲音訊號。其中，判斷規則包含各電極群組間至少間隔一電極，或各電極群組於複數個週期之兩相鄰週期中不重複使用相同之電極。
立體顯示器
(2013-06-11)
黃乙白
;
陳致維
;
沈拓江
一種立體顯示器，包括一顯示面板以及一視域掃描層。顯示面板用以快速顯示多個顯示影像。視域掃描層配置於顯示面板上，並接收這些顯示影像。此視域掃描層具有多個光線折射調變區。每一光線折射調變區包括一視域掃描單元。視域掃描單元隨一外加電場變化改變光線的行進方向，以將每一顯示影像的部份分別投射至不同的視域方向，其中每一視域方向對應光線的行進方向。
Interface Engineering to Enhance the Efficiency of Conventional Polymer Solar Cells by Alcohol-/Water-Soluble C-60 Materials Doped with Alkali Carbonates
(2013-06-12)
Lai, Yu-Ying
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Shih, Ping-I
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Li, Yi-Peng
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Tsai, Che-En
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Wu, Jhong-Sian
Two new C-60-based n-type materials, EGMC-OH and EGMC-COOH, functionalized with hydrophilic triethylene glycol groups (TEGs), have been synthesized and employed in conventional polymer solar cells. With the assistance of the TEG-based surfactant, EGMC-OH and EGMC COOH can be dissolved in highly polar solvents to implement the polar/nonpolar orthogonal solvent strategy, forming an electron modification layer (EML) without eroding the basis of ITO/PEDOT:PSS/P3HT:PC61M/EML/Ca/Al configuration with the insertion of the EGMC OH and EGMC COOH EML between the active layer and the electrode have thus been successfully realized by cost-effective solution processing techniques. Moreover, the electron conductivity of the EML can be improved by incorporating alkali carbonates into the EGMC-COOH EML. Compared to the pristine device with a PCE of 3.61%, the devices modified by the Li2CO3-doped EGMC-COOH EML achieved a highest PCE of 4.29%. Furthermore, we demonstrated that the formation of the EGMC-COOH EML can be utilized as a general approach in the fabrication of highly efficient multilayer conventional devices. With the incorporation of the EGMC-COOH doped with 40 wt % Li2CO3, the PCDCTBT-C8:PC17BM-based device exhibited a superior PCE of 4.51%, which outperformed the corresponding nonmodified device with a PCE of 3.63%.
SEMICONDUCTOR OPTICAL DEVICE HAVING AN AIR MEDIA LAYER AND THE METHOD FOR FORMING THE AIR MEDIA LAYER THEREOF
(2013-06-13)
LU Tien-Chang
;
Huang Huei-Min
;
Kuo Hao-Chung
;
Wang Shing-Chung
A method for fabricating air media layer within the semiconductor optical device is provided. The step of method includes a substrate is provided, a GaN thin film is formed on the substrate, a sacrificial layer is formed on the GaN thin film, and a nitride-containing semiconductor layer is formed on the sacrificial layer. The semiconductor optical device is immersed with an acidic solution to remove the portion of sacrificial layer to form an air media layer around the residual sacrificial layer.
A theoretical study on the strong-field ionization of the lithium atom
(2013-06-14)
Jheng, Shih-Da
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Jiang, T. F.
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物理研究所
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Institute of Physics
We apply a recently developed momentum space method (Jiang et al 2012 Phys. Rev. E 86 066702) to investigate the experimental results of strong-field ionization of the lithium atom (Schuricke et al 2011 Phys. Rev. A 83 023413). By splitting the photoelectron into groups of even and odd angular momenta and by using the states' population history, we can analyse the ionization mechanism in further detail. The lower energy double-peak structure, shown experimentally, of the photoelectron is attributed to the three-level Lambda-coupling effect. The spectral difference of 10 and 30 fs pulses at a typical intensity is demonstrated. We explain why the strong-field ionization fluctuates at intensities of 6 and 10 fs, but not for a 30 fs pulse. The change of fan-like photoelectron angular distribution with intensity in direction parallel to polarization is explained. Use of the Keldysh parameter to classify the tunnelling and multiphoton ionization is not meaningful for the lithium atom, because the ground state is mostly depleted before reaching peak intensity.
VBM reveals brain volume differences between Parkinson's disease and essential tremor patients
(2013-06-14)
Lin, Ching-Hung
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Chen, Chun-Ming
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Lu, Ming-Kuei
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Tsai, Chon-Haw
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Chiou, Jin-Chern
Symptoms of essential tremor (ET) are similar to those of Parkinsons disease (PD) during their initial stages. Presently, there are few stable biomarkers available on a neuroanatomical level for distinguishing between these two diseases. However, few investigations have directly compared the changes in brain volume and assessed the compensatory effects of a change in the parts of the brain associated with PD and with ET. To determine the compensatory and/or degenerative anatomical changes in the brains of PD and ET patients, the present study tested, via two voxel-based morphometry (VBM) approaches (Basic vs. DARTEL VBM processing), the anatomical brain images of 10 PD and 10 ET patients, as well as of 13 age-matched normal controls, obtained through a 3T magnetic resonance scanner. These findings indicate that PD and ET caused specific patterns of brain volume alterations in the brains examined. In addition, our observations also revealed compensatory effects, or self-reorganization, occurring in the thalamus and the middle temporal gyrus in the PD and ET patients, due perhaps in part to the enhanced thalamocortical sensorimotor interaction and the head-eye position readjustment, respectively, in these PD and ET patients. Such a distinction may lend itself to use as a biomarker for differentiating between these two diseases.
Ferromagnetic resonance properties of Fe81-xNixGa19/Si(1 0 0) and Fe81-yNiyGa19/glass films
(2013-06-15)
Liu, Chi-Ching
;
Jen, Shien-Uang
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Juang, Jenh-Yih
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Lo, Chi-Kuen
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電子物理學系
Two series of Fe81 xNixGa19/Si(100) and Fe81 yNiyGa19/glass films, where x or y = 0-26, were made by the magnetron sputtering method. The film thickness (t(f)) was fixed at 100 nm. We have performed three kinds of experiments on these films: (i) the saturation magnetostriction (lambda(S)) measurement; (ii) the easy-axis and hard-axis magnetic hysteresis loop measurements; and (iii) the ferromagnetic resonance (FMR) experiment to find the resonance field (H-R) with an X-band cavity tuned at f(R) = 9.6 GHz. The natural resonance frequency, f(FMR), of the Kittel mode at zero external field (H = 0) is defined as f(FMR) (sic) nu[H(K)4-pi M-S](1/2), where gamma = 2 pi nu is the gyromagnetic ratio, H-K and 4 pi M-S are the uniaxial anisotropy field and saturation magnetization, and H-K << 4 pi M-S. The Gilbert damping constant, alpha, is calculated from the formula, alpha = [nu(Delta H)(S)]/(2f(R)), where (Delta H)(exp) = (Delta H)(S) + (Delta H)(A), (Delta H)(exp) is the half-width of the absorption peak around the resonance field H-R, (Delta H)(S) is the symmetric part of (Delta H)(exp), and (Delta H)(A) is the asymmetric part. The degree of asymmetry, (Delta H)(A)/(Delta H)(exp), is associated with the structural and/or magnetic inhomogeneities in the film. The main findings of this study are as follows: (A) f(FMR) tends to decrease, as x or y increases; (B) alpha decreases from 0.052 to 0.020 and then increases from 0.020 to 0.050, as x increases, and a decreases from 0.060 to 0.013 in general, as y increases; and (C) lambda(S) reaches a local maximum when x = 22. We conclude that the Fe59Ni22Ga19/glass film should be the most suitable for application in magneto-electric microwave devices. (C) 2013 Elsevier B.V. All rights reserved.
Computational Investigation of the Adsorption and Reactions of SiHx (x=0-4) on TiO2 Anatase (101) and Rutile (110) Surfaces
(2013-06-15)
Huang, Wen-Fei
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Chen, Hsin-Tsung
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Lin, M. C.
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應用化學系
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應用化學系分子科學碩博班
The adsorption and reactions of the SiHx (x = 0-4) on Titanium dioxide (TiO2) anatase (101) and rutile (110) surfaces have been studied by using periodic density functional theory in conjunction with the projected augmented wave approach. It is found that SiHx (x = 0-4) can form the monodentate, bidentate, or tridentate adsorbates, depending on the value of x. H coadsorption is found to reduce the stability of SiHx adsorption. Hydrogen migration on the TiO2 surfaces is also discussed for elucidation of the SiHx decomposition mechanism. Comparing adsorption energies, energy barriers, and potential energy profiles on the two TiO2 surfaces, the SiHx decomposition can occur more readily on the rutile (110) surface than on the anatase (101) surface. The results may be used for kinetic simulation of Si thin-film deposition and quantum dot preparation on titania by chemical vapor deposition (CVD), plasma enhanced CVD, or catalytically enhanced CVD. (C) 2013 Wiley Periodicals, Inc.
Switchable tunneling mode for cylindrical photonic quantum well consisting of photonic crystals containing liquid crystal
(2013-06-15)
Hu, C. A.
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Yang, S. L.
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Yang, T. J.
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電子物理學系
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Department of Electrophysics
We propose a cylindrical photonic quantum well made of photonic crystals containing liquid crystals, the properties of which are theoretically calculated and investigated by the transfer matrix method in the cylindrical symmetry system. Liquid crystals are introduced into the photonic quantum well structure as tunable defect layers. When the liquid crystals are pseudo-isotropic state and the azimuthal mode order of incident waves are m=0, there were two pass-bands around certain wavelength. When the liquid crystals are homeotropic state, the reflectance of pass-band at shorter wavelength decreases from 0.75 to 0.05 in the TM mode, but the reflectance does not change in the TE mode. When mode order m=1 and the liquid crystals are pseudo-isotropic state, the reflectance of defect mode stayed the same as m=0. However, the result is reversed while the phase of liquid crystals change from pseudo-isotropic to homeotropic state. The reflectance is the same as in the TM mode, but that in the TE mode decreases substantially from 0.75 to 0.05. The application of our structure to switching device is highly potential. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.
Performance of Long-Reach Passive Access Networks Using Injection-Locked Fabry-Perot Laser Diodes With Finite Front-Facet Reflectivities
(2013-06-15)
Yeh, Chien-Hung
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Chow, Chi-Wai
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Wu, Yu-Fu
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Huang, Sung-Ping
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Liu, Yen-Liang
In this study, we use the injection-locked Fabry-Perot laser diodes (FP-LDs) with front-facet reflectivities of 10% and 35% respectively, as colorless optical networking unit (ONU) in long-reach passive optical networks (LR-PONs). Here, the injection-locked FP-LD is directly modulated at 2.5 Gbit/s on-off keying (OOK) and 10 Gbit/s orthogonal-frequency-division-multiplexing (OFDM) modulations for upstream traffic transmission over 60 km of single-mode fiber (SMF). Different operating parameters for the injection-locked FP-LD to achieve higher data rate transmission are reported.
Wavelength Tuning by Bending a Flexible Photonic Crystal Laser
(2013-06-15)
Hsu, Kung-Shu
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Chiu, Tzu-Ting
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Lee, Po-Tsung
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Shih, Min-Hsiung
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光電工程學系
This study demonstrated mechanical wavelength fine-tuning of a flexible photonic crystal (PhC) laser. A triangular PhC structure was fabricated in an InGaAsP layer on top of a polydimethylsiloxane substrate. Experiments showed two lasing modes at symmetry points K and M in the first PhC band. The laser structure was bent along the Gamma - M direction and the lasing wavelength was fine-tuned by varying the bending radius. The lasing wavelength shift is attributed to PhC lattice distortion and its tuning behavior corresponds with the simulation results. This ultra-small, wavelength-tunable laser could function as a unique light source for integrated optoelectronic circuits.
Ab Initio Chemical Kinetics for Reactions of H Atoms with SiHx (x=1-3) Radicals and Related Unimolecular Decomposition Processes
(2013-06-15)
Raghunath, Putikam
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Lee, Yun-Min
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Wu, Shang-Ying
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Wu, Jong-Shinn
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Lin, Ming-Chang
Hydrogen atoms and SiHx (x = 1-3) radicals coexist during the chemical vapor deposition (CVD) of hydrogenated amorphous silicon (a-Si: H) thin films for Si-solar cell fabrication, a technology necessitated recently by the need for energy and material conservation. The kinetics and mechanisms for H-atom reactions with SiHx radicals and the thermal decomposition of their intermediates have been investigated by using a high high-level ab initio molecular-orbital CCSD (Coupled Cluster with Single and Double)(T)/CBS (complete basis set extrapolation) method. These reactions occurring primarily by association producing excited intermediates, (SiH2)-Si-1, (SiH2)-Si-3, SiH3, and SiH4, with no intrinsic barriers were computed to have 75.6, 55.0, 68.5, and 90.2 kcal/mol association energies for x = 1-3, respectively, based on the computed heats of formation of these radicals. The excited intermediates can further fragment by H-2 elimination with 62.5, 44.3, 47.5, and 56.7 kcal/mol barriers giving Si-1, Si-3, SiH, and (SiH2)-Si-1 from the above respective intermediates. The predicted heats of reaction and enthalpies of formation of the radicals at 0 K, including the latter evaluated by the isodesmic reactions, SiHx + CH4 SiH4 + CHx, are in good agreement with available experimental data within reported errors. Furthermore, the rate constants for the forward and unimolecular reactions have been predicted with tunneling corrections using transition state theory (for direct abstraction) and variational Rice-Ramsperger-Kassel-Marcus theory (for association/decomposition) by solving the master equation covering the P, T-conditions commonly employed used in industrial CVD processes. The predicted results compare well experimental and/or computational data available in the literature. (C) 2013 Wiley Periodicals, Inc.
Enhanced Luminous Efficiency of WLEDs Using a Dual-Layer Structure of the Remote Phosphor Package
(2013-06-15)
Chen, Kuo-Ju
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Chen, Hsin-Chu
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Shih, Min-Hsiung
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Wang, Chao-Hsun
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Tsai, Hsin-Han
This study demonstrates how the insertion of a thin silicone layer into a dual-layer remote phosphor structure enhances light extraction in white light-emitting diodes (WLEDs). In the experiment, a dual-layer phosphor structure yielded a higher intensity of blue and yellow components than a conventional structure. Moreover, the lumen flux was 5% higher than a conventional remote phosphor package at the same correlated color temperature (CCT). Using a TFCalc32 simulation, the electric field intensity was calculated for different thicknesses of the dual-layer remote phosphor structures, and the enhanced use of blue rays was verified. Additionally, the dual-layer structure reduces chromaticity deviations as the driving current increases.
PQ:DMNA/PMMA photopolymer having amazing volume holographic recording at wavelength of insignificant absorption
(2013-06-15)
Chen, Yu-Fang
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Lin, June-Hua
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Lin, Shiuan Huei
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Hsu, Ken Y.
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Whang, Wha-Tzong
N, N-dimethyl-4-nitroaniline doping enables red-light holographic recording that was originally insensitive in thick phenanthrenequinone/poly(methyl methacrylate)photopolymer to have reasonable sensitivity. A volume hologram was recorded by a 647 nm laser with maximum diffraction efficiency of about 43% in a 2-mm-thick sample. A Bragg selectivity curve and an image hologram reconstruction are also demonstrated. These experimental results support recording material for volume holographic applications in an extended red spectral range. (c) 2013 Optical Society of America
珍貴文化資產　百年鐵道
(2013-06-16)
林慰
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Department of Communication and Technology
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傳播與科技學系
鐵道與國人的生活關係相當密切，台灣累積長達1世紀的鐵道文化有著豐富的內涵，從近年流行的鐵道旅行，收集車站戳章、票卷，以及鐵道攝影等活動，可看出鐵道文化不僅令人喜愛，更是人們的共同記憶。
兒童健康飲食　自主管理
(2013-06-16)
白婞嫈
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Department of Communication and Technology
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傳播與科技學系
「哈啾！」許多人對於這個詞都不陌生，甚至到了夏秋季節交替的時候，更是每天都能聽到。是什麼讓孩子在免疫系統的反應上變得較為敏感，或是缺乏抵抗力而生病呢？小孩的飲食習慣又該怎麼改變？
Clustering documents with labeled and unlabeled documents using fuzzy semi-Kmeans
(2013-06-16)
Liu, Chien-Liang
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Chang, Tao-Hsing
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Li, Hsuan-Hsun
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資訊工程學系
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Department of Computer Science
While focusing on document clustering, this work presents a fuzzy semi-supervised clustering algorithm called fuzzy semi-Kmeans. The fuzzy semi-Kmeans is an extension of K-means clustering model, and it is inspired by an EM algorithm and a Gaussian mixture model. Additionally, the fuzzy semi-Kmeans provides the flexibility to employ different fuzzy membership functions to measure the distance between data. This work employs Gaussian weighting function to conduct experiments, but cosine similarity function can be used as well. This work conducts experiments on three data sets and compares fuzzy semi-Kmeans with several methods. The experimental results indicate that fuzzy semi-Kmeans can generally outperform the other methods. (C) 2013 Elsevier B.V. All rights reserved.
瑜珈　教你如何放輕鬆
(2013-06-16)
蘇品勻
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Department of Communication and Technology
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傳播與科技學系
現代人工作繁忙，身心長時間處於緊繃的狀態，即使入睡也無法徹底放鬆，經年累月下來，使身體產生倦怠、精神不佳的情況，適當的運動能夠有效改善這些問題的產生，除了跑步、有氧，瑜珈更是許多現代人極佳選擇。