Browsing by Author "Chang, Chia-Hao"

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A general analytical solution for groundwater fluctuations due to dual tide in long but narrow islands
(2012-05-04)
Huang, Ching-Sheng
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Yeh, Hund-Der
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Chang, Chia-Hao
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環境工程研究所
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Institute of Environmental Engineering
This paper develops a general mathematical model for describing head fluctuations in an aquifer of long but narrow islands subject to a dual tide effect. The upper boundary condition of the aquifer is represented by an equation combining the simplified free surface equation with a leakage term. Such an equation is considered as a general expression representing the upper boundary condition of a confined, unconfined, or leaky confined aquifer. The closed-form solution of the model represented by two series terms is developed by the direct Fourier method and finite Fourier sine transform. One of the series can reduce to a closed-form expression by means of contour integral and residue theorem. If the width of the island is very large, this solution gives the predicted head almost the same as that of the solution for an aquifer subject to a single tide effect. It is found that the presence of an upper aquitard produces significant vertical flow in the lower leaky confined aquifer even if the aquitard permeability is low. Neglecting such vertical flow may result in an overestimate of hydraulic head in the leaky confined aquifer. The attenuation factor and phase lag predicted from the present solution subject to the dual tide effect agree well with those estimated from 57 day head fluctuation data observed at Garden Island, Australia.
A molecular forensic method for identifying species composition of processed marine mammal meats
(2014-03-01)
Chang, Chia-Hao
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Yao, Chiou-Ju
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Yu, Hsin-Yi
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Liao, Yun-Chih
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Jang-Liaw, Nian-Hong
We used universal primers designed for the cytochrome oxidase I (CO I) sequence of the order Cetacea and the family Phocidae to prove that meat fritters sold in Taiwan contained meat from two seal, six cetacean, and one pig species. The sequence information for CO I obtained in this study was limited and population genetics data for the eight sampled marine mammalian species was insufficient to deduce where these marine mammals were hunted. Regardless of the geographic origins of the marine mammal flesh, sale and consumption of marine mammals in Taiwan violates the Wildlife Conservation Act. This study provides PCR primers that could enable government testing of suspect meats to curtail the illegal trade in marine mammal products. (C) 2014 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.
A study of bulk current mechanism in P3HT-based thin film transistors and approach for current suppression
(2012-11-01)
Chang, Chia-Hao
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Chien, Chao-Hsin
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this article, poly(3-hexylthiophene) (P3HT) based thin film transistors with Ti capped source and drain electrodes (S/D) was employed to have an insight into the mechanism of bulk current effect, which led to poor subthreshold swing and large off current. Our newly developed PTFTs do show greater characteristics in the aspects of on/off current ratio and subthreshold swing than those with the conventional Au/Ti S/D. In order to explain the results, we propose that the bulk current is composed of two components, i.e., side-wall and top-face injections. We ascribe the improvements to the reduction of top-face injection bulk current due to the larger injection barrier between the P3HT and Ti. As comparing the PTFTs with Ti capped laterally grown multi-wall carbon nanotube (MWCNT) S/D with the PTFTs with MWCNT S/D, we also observe similar tendency of bulk current reduction. From the viewpoint of device operation, better subthreshold swing and smaller off current result in faster device switching and lower power consumption. By this new approach of S/D structure, there are two and 20 times improvements on the subthreshold swing and off current, respectively, although the reduction of the bulk current also leads to a slight decrease of the on-current. (C) 2012 Elsevier B.V. All rights reserved.
An Investigation of Transient Effects in Poly(3-hexylthiophenes) Based Thin Film Transistors Caused by Oxygen and Water Molecules
(2011)
Chang, Chia-Hao
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Chen, Meng-Fei
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Chien, Chao-Hsin
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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
In this article, we investigate hysteresis behavior observed in the current-voltage transfer curve of regioregular poly(3-hexylthiophene)(P3HT) based thin film transistors (PTFTs) using bi-directional voltage sweeping. According to the results of our experiments, the hysteresis effects were closely related to oxygen (O(2)) and water (H(2)O) molecules residing in the P3HT active layer. As a result, we hypothesized that O(2) and H(2)O in the P3HT could form two kinds of dopants, i.e., stable and transient states. Stable state dopants, which are commonly thought to be of the acceptor-type dopants, could induce holes in the channel region contributing to better on-current. On the contrary, transient state dopants were found to be unable to induce holes, however could enable the formation of polarization agents and create hysteresis. These two types of dopants seem have a common origin, thus they could be converted into each other through the combination of specific processes and applied external bias. From the viewpoint of device operation stability, except on-current level and characteristics including threshold voltage, off-current magnitude and on/off ratio, the impact of hysteresis should garner the attention of those pursuing high performance PTFTs. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3604963] All rights reserved.
Analysis of three-dimensional unsaturated-saturated flow induced by localized recharge in unconfined aquifers
(2018-07-20)
Chang, Chia-Hao
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Huang, Ching-Sheng
;
Yeh, Hund-Der
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環境工程研究所
;
Institute of Environmental Engineering
In the process of groundwater recharge, surface water usually enters an aquifer by passing an overlying unsaturated zone. Little attention has been given to the development of analytical solutions to a coupled unsaturated-saturated flow model due to localized recharge up to now. This paper develops a mathematical model to depict three-dimensional transient unsaturated-saturated flow in an unconfined aquifer with localized recharge on the ground surface. The model contains Richards' equation for unsaturated flow, a flow equation for saturated formation, and the Gardner constitutive model describing the behavior of unsaturated soil properties. Both flow equations are coupled through the continuity conditions of the head and flux at the water table. The semi-analytical solution to the coupled flow model is derived by the methods of Laplace transform and Fourier cosine transform. A sensitivity analysis is performed to explore the head response to the change in each of the aquifer parameters. A quantitative tool is presented to assess the recharge efficiency signifying the percentage of the water from the recharge to the aquifer. We found that the effect of unsaturated flow on the saturated hydraulic head is negligible if two criteria associated with the unsaturated soil properties and initial aquifer thickness are satisfied. The head distributions predicted from the present solution match well with those from finite-difference simulations. The predictions of the present solution also agree well with the observed data from a field experiment at an artificial recharge pond in Fresno County, California.
Authenticating the use of dried seahorses in the traditional Chinese medicine market in Taiwan using molecular forensics
(2013-09-01)
Chang, Chia-Hao
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Jang-Liaw, Nian-Hong
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Lin, Yeong-Shin
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Fang, Yi-Chiao
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Shao, Kwang-Tsao
Seahorse, which has a unique appearance and exhibits male pregnancy, is a useful component of traditional Chinese medicine (TCM). With the growing demand for TCM, vast amounts of seahorses are harvested from the wild every year and traded internationally. This study investigated 58 dried seahorse samples collected from 23 Chinese herbal medicine stores across Taiwan using molecular forensics. Results showed that eight seahorse species were present in the Taiwan TCM market. Among them, Knysna seahorse (Hippocampus capensis) has an endangered status according to the International Union for Conservation of Nature (IUCN) Red List, while the West African seahorse (Hippocampus algiricus), tiger tail seahorse (Hippocampus comes), thorny seahorse (Hippocampus histrix), great seahorse (Hippocampus kelloggi), yellow seahorse (Hippocampus kuda), hedgehog seahorse (Hippocampus spinosissimus), and three-spot seahorse (Hippocampus trimaculatus) have vulnerable status. Copyright (C) 2013, Food and Drug Administration, Taiwan. Published by Elsevier Taiwan LLC. All rights reserved.
Characteristics of an Asynchronous Rational Harmonic Mode-Locked Er-Fiber Laser
(2010)
Chang, Chia-Hao
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Jyu, Siao-Shan
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Hsiang, Wei. -Wei.
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Lai, Yinchieh
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光電工程學系
High repetition rate ultra-short optical pulse trains from an asynchronous rational harmonic mode-locked (ARHML) Er-fiber laser are experimentally demonstrated and studied. This new laser exhibits obvious advantages of pulse amplitude equalization when compared to conventional rational harmonic mode-locked fiber lasers.
Complete mitochondrial genome of the Chinese rasbora Rasbora steineri (Teleostei, Cyprinidae)
(2013-06-01)
Chang, Chia-Hao
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Tsai, Chi-Li
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Jang-Liaw, Nian-Hong
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生物科技學系
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Department of Biological Science and Technology
We describe the complete mitochondrial genome sequence of the Chinese rasbora, Rasbora steineri, which is a small cyprinid distributed in southeastern Asia. The circle genome (16,530 bp) consists of 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and 1 control region. It has the typical vertebrate mitochondrial gene arrangement.
Complete mitochondrial genome of the longfin mako shark, Isurus paucus (Chondrichthyes, Lamnidae)
(2016-01-02)
Chang, Chia-Hao
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Chiang, Wei-Chuan
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Lin, Yeong-Shin
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Jang-Liaw, Nian-Hong
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Shao, Kwang-Tsao
Here we describe the complete mitochondrial genome sequence of the longfin mako, Isurus paucus, which is a pelagic shark found in temperate and tropical waters. The circle genome (16,704bp) consists of 13 protein coding, 22 tRNA, 2 rRNA genes and 1 control region. It has the typical vertebrate mitochondrial gene arrangement.
Complete mitochondrial genome of the megamouth shark Megachasma pelagios (Chondrichthyes, Megachasmidae)
(2014-06-01)
Chang, Chia-Hao
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Shao, Kwang-Tsao
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Lin, Yeong-Shin
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Chiang, Wei-Chuan
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Jang-Liaw, Nian-Hong
Here we describe the complete mitochondrial genome sequence of the megamouth shark, Megachasma pelagios, which is an extremely rare species of deepwater shark. The circle genome (16,694 bp) consists of 13 protein coding, 22 tRNA, 2 rRNA genes and 1 control region. It has the typical vertebrate mitochondrial gene arrangement.
Complete mitochondrial genome of the Moltrecht's minnow, Aphyocypris moltrechti (Teleostei, Cyprinidae), in comparison with A. kikuchii
(2013-04-01)
Jang-Liaw, Nian-Hong
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Tsai, Chi-Li
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Chang, Chia-Hao
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Watanabe, Katsutoshi
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生物科技學系
We sequenced the complete mitochondrial genome of the Moltrecht's minnow, Aphyocypris moltrechti, which is known as an endemic species to Taiwan. The complete mitochondrial genome is 16,617 bp in size, consisting of 37 genes coding for 13 proteins, 2 rRNAs, 22 tRNAs, and 1 control region. Its gene arrangement pattern was identical with most vertebrates. We compared the mitochondrial genome of A. moltrechti with that of the Kikuchi's minnow, Aphyocypris kikuchii, which had been considered closely related to A. moltrechti within a same genus. Nucleotide sequence divergence (K2P distance) between the two whole mitochondrial genomes was 11.62%. The detailed comparison between the mitochondrial genomes of two species was done.
Complete mitogenomes of two Puntius in Taiwan: P-semifasciolatus and P-snyderi (Cypriniformes: Cyprinidae)
(2013-06-01)
Jang-Liaw, Nian-Hong
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Chang, Chia-Hao
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Tsai, Chi-Li
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生物科技學系
;
Department of Biological Science and Technology
We sequenced the complete mitochondrial genome of two spotted barbs native to Taiwan: Puntius semifasciolatus and Puntius snyderi. The complete mitochondrial genomes are 16,594 and 16,578 bp in size, respectively. Both of them contain 37 genes coding for 13 proteins, 2 rRNAs, 22 tRNAs, and 1 control region. They share the same gene arrangement pattern that was identical with most vertebrates. Nucleotide sequence divergence (K2P distance) between the two whole mitochondrial genomes was 7.63%. These two spotted barbs show very close relationship based on the comparison of the characters of their mitochondrial genomes.
Differentiation of visual spectra and nuptial colorations of two Paratanakia himantegus subspecies (Cyprinoidea: Acheilognathidae) in response to the distinct photic conditions of their habitats
(2015-05-01)
Chang, Chia-Hao
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Shao, Yi Ta
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Fu, Wen-Chung
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Anraku, Kazuhiko
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Lin, Yeong-Shin
Background: Vision, an important sensory modality of many animals, exhibits plasticity in that it adapts to environmental conditions to maintain its sensory efficiency. Nuptial coloration is used to attract mates and hence should be tightly coupled to vision. In Taiwan, two closely related bitterlings (Paratanakia himantegus himantegus and Paratanakia himantegus chii) with different male nuptial colorations reside in different habitats. We compared the visual spectral sensitivities of these subspecies with the ambient light spectra of their habitats to determine whether their visual abilities correspond with photic parameters and correlate with nuptial colorations. Results: The electroretinogram ( ERG) results revealed that the relative spectral sensitivity of P. h. himantegus was higher at 670 nm, but lower at 370 nm, than the sensitivity of P. h. chii. Both bitterlings could perceive and reflect UV light, but the UV reflection patterns differed between genders. Furthermore, the relative irradiance intensity of the light spectra in the habitat of P. h. himantegus was higher at long wavelengths (480-700 nm), but lower at short wavelengths (350-450 nm), than the light spectra in the habitats of P. h. chii. Conclusions: Two phylogenetically closely related bitterlings, P. h. himantegus and P. h. chii, dwell in different waters and exhibit different nuptial colorations and spectral sensitivities, which may be the results of speciation by sensory drive. Sensory ability and signal diversity accommodating photic environment may promote diversity of bitterling fishes. UV light was demonstrated to be a possible component of bitterling visual communication. The UV cue may assist bitterlings in gender identification.
DNA barcode identification of fish products in Taiwan: Government-commissioned authentication cases
(2016-08)
Chang, Chia-Hao
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Lin, Han Yang
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Ren, Qiu
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Lin, Yeong-Shin
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Shao, Kwang-Tsao
Mislabeling of fish products not only impacts consumer finances, but can also be deleterious to public health. Fish products may be mislabeled for reasons including ambiguity of common fish names, challenging morphological identification, or willful intention to deceive. We reveal a high rate of mislabeling (70%) in 34 samples from 17 cases entrusted to us by three different Customs offices and one Coastal Patrol Office in Taiwan using DNA barcoding based on a partial segment of the mitochondrial cytochrome c oxidase subunit I gene (COI). In order to reduce the mislabeling of imported fish products, the authorities should take some actions into consideration, such as institutionalizating molecular authentication of fish products, standardizing the usage of common fish names, and legislating for penalties. (C) 2016 Elsevier Ltd. All rights reserved.
Enhanced Performance of Poly(3-hexylthiophenes) Based Thin Film Transistors Using Double-Coated Active Layer
(2012)
Chang, Chia-Hao
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Chien, Chao-Hsin
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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 study demonstrates that thin-film transistors with double-coated poly(3-hexylthiophene) (P3HT) channel layers (DPTFTs), which are formed by coating a second P3HT layer on top of the N-2-annealed first P3HT layer, show a higher on/off current ratio and better subthreshold swing, compared to single-layer P3HT transistors (PTFTs). Characteristics of DPTFTs were investigated by varying the thicknesses of the first P3HT layer and the second P3HT layer. Moreover, DPTFTs with an as-prepared first layer, i.e., without N-2 annealing, were also prepared for comparison. A thin gate oxide was incorporated into the DPTFTs, which resulted in an impressive subthreshold swing (smaller than 1 V/decade). Furthermore, the study proposes new DPTFTs with an N-2-annealed first layer and a functionalized single-wall carbon nanotube (F-SWNCT)-doped P3HT second layer. Significant improvements are observed not only in subthreshold swing and on/off current ratio but also in mobility induced by the innovative channel structure and doping of F-SWCNTs, respectively. (C) 2012 The Electrochemical Society. All rights reserved.
Functionalized Single-Walled Carbon-Nanotube-Blended P3HT-Based Thin-Film Transistors With Multiwalled Carbon-Nanotube Source and Drain Electrodes
(2011-10-01)
Chang, Chia-Hao
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Chien, Chao-Hsin
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We demonstrate the superior performance of thin-film transistors with a functionalized single-walled carbon-nanotube-blended poly(3-hexylthiophene) (F-SWCNT-P3HT) channel and multiwalled CNT source and drain electrodes (MWCNT S/Ds). Compared with transistors with a P3HT channel and gold electrodes, the mobility of transistors with an F-SWCNT-P3HT channel and MWCNT S/Ds is increased by more than one order of magnitude, i.e., from 0.0052 to 0.072 cm(2)/V . s. This improvement results not only from the well-known fast carrier transport assisted by the blend of F-SWCNTs but also, more importantly, from the reduced contact resistance between P3HT and MWCNT S/Ds.
GnRH mRNA levels in male three-spined sticklebacks, Gasterosteus aculeatus, under different reproductive conditions
(2015-02-01)
Shao, Yi Ta
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Tseng, Yung Che
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Chang, Chia-Hao
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Yan, Hong Young
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Hwang, Pung Pung
In vertebrates, reproduction is regulated by the brain-pituitary-gonad (BPG) axis, where the gonadotropin-releasing hormone (GnRH) is one of the key components. However, very little is known about the possible role of GnRH in the environmental and feedback control of fish reproduction. To investigate this, full-length gnrh2 (chicken GnRH II) and gnrh3 (salmon GnRH) sequences of male three-spined sticklebacks (Gasterosteus aculeatus), which are clustered with the taxa of the same GnRH type as other Euteleostei, were cloned and annotated. gnrh1 is absent in this species. The mRNA levels of gnrh2 and gnrh3 in the sticklebacks\' brain were measured under breeding and post-breeding conditions as well as in castrated and sham-operated breeding fish and castrated/sham-operated fish kept under long-day (LD 16:8) and short-day (LD 8:16) conditions. Fully breeding males had considerably higher mRNA levels of gnrh2 and gnrh3 in the thalamus (Th) and in the telencephalon and preoptic area (T + POA), respectively, than post-breeding males. Sham-operated breeding males have higher gnrh3 mRNA levels than the corresponding castrated males. Moreover, higher gnrh2 mRNA levels in the Th and higher gnrh3 mRNA levels in the T + POA and hypothalamus (HypTh) were also found in long-day sham-operated males than in sham-operated fish kept under an inhibitory short day photoperiod. Nevertheless, gnrh2 and gnrh3 mRNA levels were not up-regulated in castrated males kept under long-day photoperiod, which suggests that positive feedbacks on the brain-pituitary-gonad axis are necessary for this response. (C) 2014 Elsevier Inc. All rights reserved.
Low-threshold InGaAs/GaAsSb \'W\'-type quantum well laser on InP substrate
(2014)
Chang, Chia-Hao
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Li, Zong-Lin
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Lu, Hong-Ting
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Lee, Chien-Ping
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Lin, Sheng-Di
The mid-infrared electrically-driven laser using InGaAs/GaAsSb \'W\'-type QWs is demonstrated at room temperature. The InP-based laser lasing at 2.35 mu m with the lowest threshold current density of 1.42 kA/cm(2) is presented.
Low-Threshold Short-Wavelength Infrared InGaAs/GaAsSb \'W\'-Type QW Laser on InP Substrate
(2015-02-01)
Chang, Chia-Hao
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Li, Zong-Lin
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Lu, Hong-Ting
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Pan, Chien-Hung
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Lee, Chien-Ping
The electrically driven short-wavelength infrared semiconductor laser using InP-based InGaAs/GaAsSb W-type quantum wells (QWs) is investigated. Using Sb-free separate confined layer and engineered QWs, the laser lasing at 2.35 mu m exhibits a low-threshold current density at infinite cavity length of 83 A/cm(2) per QW under pulsed operation at room temperature. The internal loss alpha(i) and internal quantum efficiency eta(i) of the laser are 17.5 cm(-1) and 15%, respectively.
ON THE EFFECT OF DATA IMBALANCE FOR MULTI-LABEL PEDESTRIAN ATTRIBUTE RECOGNITION
(2018-01-01)
Wang, Tsaipei
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Shu, Kai-Chen
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Chang, Chia-Hao
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Chen, Yi-Fu
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資訊工程學系
Pedestrian attribute recognition has many applications in surveillance and attribute based query, tracking, and person re-identification. The recent trend in deep-learning based pedestrian attribute recognition is to use a shared CNN backbone for feature extraction and multiple subsequent branches for the individual branches. While this allows the end-to-end learning to simultaneously recognize multiple attributes, the data imbalance problem of most attributes becomes a challenge that has not been studied sufficiently for this application. This paper presents studies on how the cost adjustment method affects several common evaluation metrics. We also propose a two-stage training procedure, where an additional fine-tuning stage on the classifier layers only with class-balanced data is shown to improve recognition performances.