Browsing by Author "Lai, Yu-Sheng"

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A Wireless Biomedical Sensor Network using IEEE802.15.4
(2009)
Tseng, Shao-Yen
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Tsai, Chung-Han
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Lai, Yu-Sheng
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Fang, Wai-Chi
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電子工程學系及電子研究所
The advancements of wireless body area networks (WBAN) and wireless personal area networks (WPAN) has led to a recent increase of viable applications in wireless medical and healthcare devices. Developing biomedical sensors such as electroencephalograph (EEG) and electrocardiogram (ECG) sensors often require numerous connecting wires which may introduce noise and increase patient discomfort In this paper we propose a system design and realization of a wireless EEG and ECG sensor network focusing on issues such as time synchronization, bandwidth, and power constraints constituent of WBANs. Our WSN comprises three transmitting nodes for a total of four EEG channels and an ECG channel. We solve problems such as data throughput requirements for EEG and ECG signal processing as well as time synchronization of received data at the base station. This paper keeps in consideration the possible implementation of our proposed system onto a system-on-chip (SOC) by putting focus on the chip size and low power consumption of the analog-front-end system.
Alignment of Stretchable Nanoparticle Chains with Tunable Optical Properties Formed from Molecular Machinery
(2013-01-01)
Lin, Ming-Yu
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Lu, Yen-Pei
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Yang, Yuh-Shyong
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Chen, Hsuen-Li
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Yang, Chih-Hui
Control orientation and interparticle spacing of self-assembled nanoparticles can provide versatile functional materials for optical and electronic applications. In this study, we have obtained a glass substratum with tunable optical properties using flowing control and bimolecular competition. The surface of glass was modified from immobilized stretchable gold nanoparticle chains. The long and periodic single-stranded DNA nanotemplates were prepared using Phi29 DNA polymerase molecular machinery according to precise molecular biology regulation. Gold nanoparticle (Au NP) docked at the default sites of the nanotemplates and optical anisotropic absorption were enhanced by approximately 55 % by using tunable, flexible, and oriented one-dimensional metallic nanostructures.
Efficiency Enhancement and Sensitive Broadband 1Hz similar to 1kHz of Power Generator by Recycling Vibration Energy on Automobile
(2012)
Wei, Mao-Qugn
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Ko, Fu-Hsiang
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Sun, Tai-Ping
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Chen, Hsuen-Li
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Lin, Yung-Bin
Based on novel design of moveable magnet between two mutually inimical magnetic forces without strict fabrication, for the first time, we demonstrate successfully a producible power generator with significant efficiency enhancement at broadband frequency range of 1 Hz similar to 1 kHz, 3D-colis stack-ability for output voltage improvement, and recycling vibration energy on automobile simultaneously. Even though the vibration frequency is as low as 1 Hz, two orders-of-magnitude improvements in normalized power (the ratio of power to product of external force and coil turns) provided from previous reports can be obtained. Further, comparing our device with maturely accelerometer chip (MMA7361) indicates that proposed strategies benefit harvesting vibration energy on driving automobile indeed. This vibrated power generator in-turn provides high potential for applications, such as human motion (1 Hz similar to 2 Hz), sporting (5 Hz similar to 10 Hz), and automotive (10 Hz similar to 1 kHz) etc..
High Optical Conversion Capability within the Interface between Graphene and Si under Zero Bias and Visible to Near Infrared Regime
(2016)
Hsiao, Chin-Chiang
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Wei, Mao-Qugn
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Ren, Ting-Ting
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Chen, Bo-Yi
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Li, Mei-Yi
In this study, we demonstrate the high performance few-layer graphene-Si sensor with high photoresponsivity of 95 mA/W, operation behaviors with external bias as low as 0 V, and broadband operating light wavelength from 400 nm to 1000 nm by combining high transparency of few-layer graphene and n-type silicon. Although external bias benefits the photoresponsivity, the larger dark current is the price to pay. Under zero bias, the different Si substrate, n-type or p-type, provides variant Schottky barrier height guiding different photoelectrical behavior also be investigated in this work. According to the experimental results, few-layer graphene over p-type silicon (FLG p-Si) has one order higher the dark current of the few-layer graphene over n-type silicon (FLG n-Si) to ensure that the detection region between few-layer graphene and n-type silicon profits high optical-to-electrical conversion. Further, the capability of photocurrent-to-photovoltage conversion directly in one device is also provided and verified to profit the integration proposed device with periphery circuit easily.
High Photothermal Properties in Silicon Nanostructures
(2016)
Ren, Ting-Ting
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Wei, Mao-Qugn
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Hsiao, Chin-Chiang
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Chen, Bo-Yi
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Li, Mei-Yi
This research describes the p-type nanostalactites (p-type NS) with high photothermal conversion capability has been demonstrated by rapid INC process without extra heat treatment. In optical property, p-type NS has ultralow reflectance below 5 % and high light absorption due to rough structures in the broadband wavelength (350 nm -1100 nm). It looks like a black body. Silicon, an indirect band material, can release thermal energy during the recombination process of photo-generated electron-hole pairs. P-type NS converts photon energy into heat rapidly and then photothermal effect occurs. Then, the temperature change of p-type NS is faster in 10 second than bulk p-type silicon. These nanostructures can not only enhance thermal conversion efficiency but be regarded as a great heat absorber.
Reconfigurable Multi-Resolution Performance Profiling in Android Applications
(2013-09-01)
Lin, Ying-Dar
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Chang, Kuei-Chung
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Lai, Yuan-Cheng
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Lai, Yu-Sheng
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資訊工程學系
The computing of applications in embedded devices suffers tight constraints on computation and energy resources. Thus, it is important that applications running on these resource-constrained devices are aware of the energy constraint and are able to execute efficiently. The existing execution time and energy profiling tools could help developers to identify the bottlenecks of applications. However, the profiling tools need large space to store detailed profiling data at runtime, which is a hard demand upon embedded devices. In this article, a reconfigurable multi-resolution profiling (RMP) approach is proposed to handle this issue on embedded devices. It first instruments all profiling points into source code of the target application and framework. Developers can narrow down the causes of bottleneck by adjusting the profiling scope using the configuration tool step by step without recompiling the profiled targets. RMP has been implemented as an open source tool on Android systems. Experiment results show that the required log space using RMP for a web browser application is 25 times smaller than that of Android debug class, and the profiling error rate of execution time is proven 24 times lower than that of debug class. Besides, the CPU and memory overheads of RMP are only 5% and 6.53% for the browsing scenario, respectively.
RF-Powered Li-Ion Battery Charger for Biomedical Applications
(2009)
Chuang, Chih-Wen
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Chua, Ericson Go
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Lai, Yu-Sheng
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Fang, Wai-Chi
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電子工程學系及電子研究所
An integrated RF-powered Li-ion battery charger solution has been developed for biomedical applications. RF energy received through an antenna is rectified, regulated, and passed on to a battery charger circuit that charges a Li-ion battery efficiently and accurately. The charger system has been implemented using UMC 90nm BiCMOS process library. Experimental results show that a battery model with internal resistance of 300m Omega and internal capacitance of 10mF can be charged to its full capacity at 3.5V in 0.2ms by a 2mW 10MHz RF power source referred from the antenna. The implemented charger circuit consumes only 240 uW.
THE INCREMENTAL VALUE OF A FUTURES HEDGE USING REALIZED VOLATILITY
(2010-09-01)
Lai, Yu-Sheng
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Sheu, Her-Jiun
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管理科學系
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Department of Management Science
A number of prior studies have developed a variety of multivariate volatility models to describe the joint distribution of spot and futures, and have applied the results to form the optimal futures hedge. In this study, the authors propose a new class of multivariate volatility models encompassing realized volatility (RV) estimates to estimate the risk-minimizing hedge ratio, and compare the hedging performance of the proposed models with those generated by return-based models. In an out-of-sample context with a daily rebalancing approach, based on an extensive set of statistical and economic performance measures, the empirical results show that improvement can be substantial when switching from daily to intraday. This essentially comes from the advantage that the intraday-based RV potentially can provide more accurate daily covariance matrix estimates than RV utilizing daily prices. Finally, this study also analyzes the effect of hedge horizon on hedge ratio and hedging effectiveness for both the in-sample and the out-of-sample data. (C) 2009 Wiley Periodicals, Inc. Jrl Fut Mark 30:874-896,2010