Browsing by Author "Huang, JH"

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Arsenic precipitate accumulation in alternately Si/Be delta-doped GaAs grown by low-temperature molecular beam epitaxy
(1998-03-15)
Hsieh, LZ
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Huang, JH
;
Su, ZA
;
Wu, MC
;
電子物理學系
The precipitation of arsenic in alternately [Si]=1.0 x 10(13) cm(-2) and [Be]=1.0 x 10(14) cm(-2) delta-doped GaAs grown at low temperature by molecular beam epitaxy has been studied using transmission electron microscopy. Following annealing at 600, 700 and 800 degrees C, As precipitates were found to form preferentially not only on planes of Si but also on planes of Be. The as-grown and annealed samples were also characterized using secondary ion mass spectroscopy, and the results revealed that the interdiffusion of Si and Be dopants due to annealing was discernible. This is the first observation of As precipitate accumulation on Be delta-doped planes in low-temperature grown GaAs.
Color-tunable multilayer light-emitting diodes based on conjugated polymers
(2004-02-16)
Huang, CC
;
Meng, HF
;
Ho, GK
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Chen, CH
;
Hsu, CS
Wide-range low-voltage continuous color tuning is achieved in multilayer light-emitting diodes based exclusively on the commonly used high-efficiency electroluminescent conjugated polymers. There are three layers for red, green, and blue emission, and one extra layer for electron blocking. The color of the emitted photon depends on the position of the electron-hole recombination. Due to the stronger field dependence of the electron mobility relative to the hole mobility, the recombination zone is pushed away from the cathode and concentrated in different emissive layers as the voltage increases. (C) 2004 American Institute of Physics.
Consumer attitude toward gray market goods
(2004)
Huang, JH
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Lee, BCY
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Ho, SH
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管理科學系
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Department of Management Science
Gray market activities have become global, occurring not only in less developed or volatile markets, but also in many well-developed markets. Although the gray market problem has been discussed in the literature, pertinent research from a demand perspective remains scarce. This study establishes a valid measure of consumer attitude toward gray market goods and investigates the relationships between consumer attitude toward gray market goods and their antecedents. Data analysis reveals that both Price-quality inference and risk averseness significantly and negatively affect consumer attitude toward gray market goods. Strategies for managers of international brands to address gray market problems are presented.
Coverage and capacity of a wireless mesh network
(2005)
Huang, JH
;
Wang, LC
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Chang, CJ
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電信工程研究所
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Institute of Communications Engineering
Wireless mesh networks (WMN) will play an important role in the next-generation Wireless communication systems because it can support broadband services with ubiquitous coverage by low transmission power. In this paper, we propose a multi-channel ring-based wireless mesh network and develop an analytical framework to evaluate the capacity and coverage of such a network. In the analytical framework, we first establish a physical (PHY)/medium access control (MAC) cross-layer throughput performance model by including the carrier sense multiple access (CSMA) MAC protocol and distance-based rate adaptation with multi-hop connections. Based on the derived throughput model, we apply the mixed-integer nonlinear programming (MINLP) optimization approach to maximize the capacity (throughput) and service coverage of a mesh cell, in which the number of rings in a mesh cell and the radius for each ring are determined.
Cultural values as manifested in US and Taiwan television advertising
(1995)
Huang, JH
;
交大名義發表
;
National Chiao Tung University
Deployment strategies of access points for outdoor wireless local area networks
(2005)
Huang, JH
;
Wang, LC
;
Chang, CJ
;
電信工程研究所
;
Institute of Communications Engineering
In this paper, we investigate the issues of deploying access points for wireless local area networks (WLANs) in an outdoor environment, where several adjacent access points (APs) will form a cluster and in each cluster access points are connected through wireless repeaters to ease deployment. Access points are usually placed aiming to maximize its cell coverage. Nevertheless, a larger coverage distance will lead to a lower throughput for the wireless repeater. We apply the mixed-integer nonlinear programming (MINLP) optimization approach to determine the number of access points in a cluster and the best separation distance between access points. The objective is to maximize the ratio of the total carried traffic load to the total cost for a cluster of APs connected by wireless repeaters. In this paper, the uniform-spacing and the increasing-spacing placement strategies for access points are proposed and compared. Our results show that the increasing-spacing placement strategy outperforms the uniform-spacing placement strategy in terms of an objective function considering total carried traffic load, the number of access points, and the cost connecting an AP to the backbone network.
Earthquake devastation and recovery in tourism: the Taiwan case
(2002-04-01)
Huang, JH
;
Min, JCH
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管理科學系
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經營管理研究所
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Department of Management Science
The most serious earthquake in Taiwan of the 20th century struck the central region of the island on September 21, 1999. The so-called September 21 Earthquake, measuring 7.3 on the Richter scale, dealt a sharp blow to the Taiwanese tourism industry, with the worst impact being suffered by the international tourism sector. To revitalize the dramatic decline in inbound tourist flows, the government of Taiwan implemented a series of swift countermeasures. The purpose of this study is to evaluate whether Taiwan tourism has rebounded completely from the crisis. This research establishes a model for Taiwan's inbound demand to predict the volume of visitor arrivals after the quake (September 1999 to July 2000). The forecasts are based on the seasonal autoregressive integrated moving average (SARIMA) model which are then compared with the actual volume of visitor arrivals to analyze the recovering status. Empirical results indicate that the island's inbound arrivals have not yet fully recovered from the earthquake's devastation after 11 months. (C) 2002 Elsevier Science Ltd. All rights reserved.
Effect of substrate orientation on arsenic precipitation in low-temperature-grown GaAs
(2005-09-01)
Lee, WN
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Chen, YF
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Huang, JH
;
Guo, XJ
;
Kuo, CT
Arsenic precipitation in "superlattice" structures of alternately undoped and [Si] = 3 x 10(18) cm(-3)-doped GaAs grown at 250 degrees C on (100), (311)A, and (311)B GaAs substrates has been studied using transmission electron microscopy. It is found that upon postgrowth annealing at 800 degrees C, As precipitates are nearly confined in the Si-doped regions, forming two-dimensional cluster arrays located approximately at the center of each Si-doped layer. The results also show that the As precipitates in the (311)B substrate are slightly denser and larger than those in the (311)A substrate and both are markedly denser and larger than those in the (100) substrate. This can be attributed to the varying excess arsenic incorporations in differently orientated substrates.
Effects of annealing on magnetic properties of new ferromagnetic semiconductor (In, Al, Mn) As
(2005-10-01)
Chen, YF
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Lee, WN
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Huang, JH
;
Chin, TS
;
Guo, XJ
The effects of low-temperature (210 degrees C-290 degrees C) annealing on the microstructure, lattice constant, and magnetic properties of (In0.52Al0.48)(0.91)Mn0.09As grown by low-temperature molecular-beam epitaxy were studied. The results show that low-temperature annealing has little influence on the crystalline structure and interface quality Of (In0.52Al0.48)(0.91)Mn0.09As epilayer. In contrast, both the lattice constant and Curie temperature of (In0.52Al0.48)(0.91)Mn0.09As are found to be strongly dependent on the annealing temperature. The lattice constant linearly decreases with increasing annealing temperature; while the Curie temperature increases with increasing annealing temperature up to 250 degrees C, and then abruptly decreases upon further annealed at 270 degrees C and 290 degrees C.
Effects of doping type and concentration on precipitation of nanometer arsenic clusters in low-temperature-grown GaAs
(2005-11-01)
Lee, WN
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Chen, YF
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Huang, JH
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Guo, XJ
;
Kuo, CT
In this study, the effects of doping type and concentration on arsenic precipitation in low-temperature-grown GaAs upon postgrowth annealing at 600, 700. and 800 degrees C were investigated. Three undoped/Si-doped/undoped (i-n-i) regions and three undoped/Be-doped/ undoped (i-p-i) regions were grown by low-temperature Molecular beam epitaxy, The results show that arsenic precipitation is dependent on doping type and doping concentration. Arsenic depletion was observed in all Be-doped layers for all annealing temperatures. However, a "dual" arsenic precipitation behavior was observed in Si-doped layers: As accumulates in [Si]=2 X 10(18) cm(-3) doped layers, while it depletes in [Si]=2 X 10(16) and 2 X 10(17) cm(-3) doped layers, We attribute this "dual" As precipitation phenomenon in Si-doped layers to the different depletion depths. (c) 2005 American Vacuum Society.
Electron-electron scattering times in low-diffusivity thick RuO2 and IrO2 films
(1999-01-01)
Lin, JJ
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Xu, W
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Zhong, YL
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Huang, JH
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Huang, YS
We have systematically measured the electron dephasing scattering times from a three-dimensional weak-localization study of low-diffusivity thick RuO2 and IrO2 films. We find that the inelastic electron scattering rate 1/tau(in) varies essentially Linearly with the temperature and there is essentially no dependence of 1/tau(in) on the electron elastic mean free path. This observation is understood in terms of the current theoretical concept for electron-electron scattering in strongly disordered bulk conductors. [S0163-1829(99)02601-6].
Enhancing the thermal and spectral stabilities of polyfluorene-based bluelight-emitting materials by incorporating pendent spiro-cycloalkyl groups
(2004-05-20)
Wu, FI
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Dodda, R
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Jakka, K
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Huang, JH
;
Hsu, CS
We have synthesized polyfluorene-based copolymers containing spiro-cycloalkyl groups functionalized on the C-9 position of alternate fluorene units using the Suzuki coupling reaction. The presence of the rigid spiro-cycloalkyl pendent groups not only hinders the close packing and intermolecular interactions between polymer chains, but also preserves the molecular rigidity of the polymer, leading to polyfluorenes with high glass transition temperatures and improved thermal and spectral stabilities. The results of photoluminescence measurements of the isothermally heated spiro-polyfluorene thin films (150degreesC for 20h) show that the commonly observed aggregate/excimer formation is suppressed effectively in these polymers. Blue electroluminescence was demonstrated in a double-layer LED device using the spiro-derivatized polyfluorene as the emitting layer. (C) 2004 Elsevier Ltd. All rights reserved.
Fast optical flow estimation and its application to real-time obstacle avoidance
(2001)
Song, KT
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Huang, JH
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電控工程研究所
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Institute of Electrical and Control Engineering
This paper presents a novel fast optical flow estimation algorithm and its application to real-time obstacle avoidance of a guide-dog robot. The function of the laboratory-developed robot is to help blind or visually impaired pedestrians to move safely among obstacles. The proposed algorithm features a combination of the conventional correlation-based principle and the differential-based method for optical flow estimation. Employing image intensity gradients as features for pattern matching, we set up a brightness constraint to configure the search area. The merit of this scheme is that the computation load can be greatly reduced and in the mean time the possibility of estimation error is decreased. The vision system has been established on board the robot to provide depth information of the immediate environment. The depth data are transformed to a safety distribution histogram and used for real-time obstacle avoidance. Experimental results demonstrate that the proposed method is effective for a guidance robot in a dynamic environment.
Fluorescent conjugated polymer films as TNT chemosensors
(2004-08-13)
Chang, CP
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Chao, CY
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Huang, JH
;
Li, AK
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Hsu, CS
Three prototypical light emitting conjugated polymers, two poly(p-phenylene vinylenes) (MEH-PPV and DP10-PPV) and a poly(diphenylacetylene), were examined for chemosensor applications to detect explosive compounds such as 2,4,6-trinitrotoluene (TNT) and 2,4- and 2,6-dinitrotoluene (DNTs). All polymer thin films showed high fluorescence quenching sensitivity towards TNT and DNTs, indicating that a wide range of emissive conjugated polymers are potentially useful chemosensor materials for detecting landmines. The relative sensitivity of fluorescence quenching of the polymers by the analytes has been rationalized in terms of the vapor pressure of the analytes, the solubility parameters of the polymers and the analytes, and the relative energy levels of the polymers. (C) 2004 Elsevier B.V. All rights reserved.
Formation of two-dimensional arsenic precipitation in superlattice structures of alternately undoped and heavily Be doped GaAs with varying periods grown by low-temperature molecular beam epitaxy
(1998-05-01)
Su, ZA
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Huang, JH
;
Lee, WI
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電子物理學系
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Department of Electrophysics
As precipitates in superlattice structures of alternately undoped and [Be] = 2.4 x 10(20) cm(-3) doped GaAs with varying periods grown by molecular beam epitaxy at low substrate temperatures were studied by transmission electron microscopy. Never arsenic precipitate microstructures were observed in annealed samples, including preferential accumulation of precipitates inside the Be-doped GaAs but near each interface of Be-doped GaAs and the following grown undoped GaAs. The confinement reaches the extreme for samples annealed at 800 degrees C, where the precipitates appear as dot arrays along such interfaces and leave other areas almost free of precipitates. The incorporation of substitutional Be accepters is believed to cause a smaller lattice constant in the heavily Be-doped regions than in the undoped regions. A strain-induced mechanism was proposed to account for the preferential segregation of As clusters, though the underlying mechanism is not fully clear. (C) 1998 Elsevier Science B.V. All rights reserved.
Herding in online product choice
(2006-05-01)
Huang, JH
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Chen, YF
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管理科學系
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Department of Management Science
Previous research has shown that people are influenced by others when making decisions. This work presents three studies examining herding in product choices on the Internet. The first two studies addressed how two cues frequently found on the Internet, that is, sales volume and customer reviews, influence consumer on-line product choices. The third study examined the relative effectiveness of two recommendation sources. The experimental results revealed that subjects used the choices and evaluations of others as cues for making their own choices. However, herding effects are offset significantly by negative comments from others. Additionally, the recommendations of other consumers influence the choices of subjects more effectively than recommendations from an expert. Finally, implications of this work are discussed. (c) 2006 Wiley Periodicals, Inc.
(In0.52Al0.48)(1-x)MnxAs muted magnetic semiconductor grown on InP substrates
(2006-01-11)
Lee, WN
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Chen, YF
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Huang, JH
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Guo, XJ
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Kuo, CT
A series of diluted magnetic semiconductors, (In0.52Al0.48)(1-x)MnxAs (0 < x <= 0. 11), was successfully grown on InP substrate by low-temperature molecular beam epitaxy. Our results indicate that (In0.52Al0.48)(1-x)MnxAs exhibits interesting magnetic behaviours at 5 K: it shows paramagnetic-like behaviour when x <= 0.05 and ferromagnetic behaviour when x >= 0.06.
MBE growth and structural and magnetic properties of (In1-gamma Al gamma)(1-x)MnxAs-diluted magnetic semiconductors
(2006-04-01)
Lee, WN
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Chen, YF
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Huang, JH
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Guo, XJ
;
Kuo, CT
A series of quaternary-diluted magnetic semiconductors, (In1-y,Al-y)(1-x)MnxAs, have been successfully grown on InP substrates by low-temperature molecular beam epitaxy. The (ln(0.52)Al(0.48))(1-x)MnxAs with x <= 0.11 were grown on a nearly lattice-matched In0.52Al0.48As buffer, while the (In1-y,Al-y)(1-x)MnxAs with a higher Mn content of 0.11 < x <= 0.18 were grown on a graded 3-layer In,-,,Al-y 'As buffer structure. The results of transmission electron microscopy and double-crystal X-ray diffraction reveal that all (In1-yAly)(1-x),Mn,As epilayers are single crystal with zincblende structure, and the lattice constant increases with increasing the Mn content. The magnetic measurements show that the (In1-y,Al-y)(1-x)MnxAs semiconductors exhibit a paramagnetic-like state for x <= 0.05 while a ferromagnetic state for x >= 0.05, and the Curie temperature of ferromagnetic (In1-yAly)(1-x) MnxAs increases with increasing Mn content. (c) 2006 Elsevier B.V. All rights reserved.
Measuring satisfaction with business-to-employee systems
(2004-01-01)
Huang, JH
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Yang, C
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Jin, BH
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Chiu, H
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管理科學系
Marketing the products of other companies within an individual company Intranet can benefit both employees and the company itself. Understanding what constitutes a satisfying experience on the part of the employees is crucial for developing successful business-to-employee systems. While end-user computing satisfaction has been studied extensively, new aspects such as purchasing convenience, product prices in the system and product delivery have to be included. This study develops an instrument for reliably and accurately measuring business-to-employee success. Test-retest reliability and construct validity are examined. The results of this study show that convenience, delivery, interface, accuracy, price and security influence employee assessments of satisfaction. Managers can use the instrument developed here to assess the success of their business-to-employee systems. (C) 2003 Elsevier Ltd. All rights reserved.
Perceived fairness of pricing on the Internet
(2005-06-01)
Huang, JH
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Chang, CT
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Chen, CYH
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管理科學系
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經營管理研究所
The perceived fairness of price changes has been a subject of much inquiry in economic and marketing literature. This paper examines consumers' perceptions of the fairness of pricing on the Internet. Fair prices on the Internet, pricing mechanisms, methods of price discrimination and yield management are investigated from a consumer's perspective. Results obtained from 276 questionnaires collected in Taiwan indicate that the Internet prices that equal those in the traditional channels are perceived to be unfair. Respondents considered various pricing mechanisms on the Internet to be fair while many practices of price discrimination and yield management were perceived to be unfair. © 2004 Elsevier B.V. All rights reserved.