Browsing by Author "Peng, WC"

Now showing 1 - 10 of 10

Accuracy of the EasyTouch blood glucose self-monitoring system: a study of 516 cases
(2004-11-01)
Dai, KS
;
Tai, DY
;
Ho, P
;
Chen, CC
;
Peng, WC
Background: Self-monitoring blood glucose device is an important toot for diabetes patients to efficiently control their blood glucose concentrations. We evaluated the accuracy of EasyTouch glucose monitoring system. Methods: Capillary blood glucose concentrations measured using EasyTouch and the reference values obtained from Yellow Springs Instruments (YSI) 2300 STAT were performed in the Department of Laboratory Medicine, Wei-Gong Memorial Hospital. Results were evaluated using (1) linear regression analysis, (2) Clarke Error Grid analysis, (3) percentage of readings within a defined range of deviation from the reference value, (4) bias plots, and (5) coefficients of variation (CVs) calculated from 60 measurements in series. Results: The window of the 516 EasyTouch readings covered a range from 42 to 555 mg/dl. Linear regression analysis yielded a regression slope 0.9972, intercept 1.899 mg/dl, r(2) 0.9571, and Syx 14.89 mg/dl. A Clarke Error Grid analysis showed 100% of the EasyTouch readings in clinically acceptable zones A and B. Of the EasyTouch readings, 98.3%, 91.9%, 78.3% and 46.9% were found within +/-20%, +/-15%, +/-10%, and +/-5%, respectively, of the reference values. Further analysis showed that the percentage of EasyTouch readings within the defined intervals was similar in three glucose ranges (less than or equal to100, 101-200, and greater than or equal to201 mg/dl). The CVs for the four lots of strips (lot 1 to lot 4) ranged from 3.5 to 5.5%, 2.1 to 4.8%, 1.8 to 3.6%, and 3.0 to 5.7%, respectively. Conclusions: EasyTouch provides high accurate and precise glucose readings over a wide range of glucose concentrations. (C) 2004 Elsevier B.V. All rights reserved.
AlGaInP light-emitting diodes with metal substrate fabricated by wafer bonding
(2003)
Peng, WC
;
Wu, WCS
;
材料科學與工程學系
;
Department of Materials Science and Engineering
AlGaInP LED with copper Substrate has been successfully fabricated by the wafer bonding technique in this study. it was found that bonded AlGaInP LED devices could be operated in a higher injection forward current above 500mA. Such bonding enhanced the device performance significantly. The joule heating exhibiting in conventional LEDs was eliminated because the copper substrate provided a good heat sink. Thus, the thermal degradation of the conventional LEDs was improved.
An effective broadcast program generation algorithm for dependent data
(2005)
Huang, JL
;
Peng, WC
;
資訊工程學系
;
Department of Computer Science
We explore in this paper the problem of broadcasting dependent data in multiple broadcast channels, and explicitly investigate the effect of data replication. By analyzing the model of dependent data broadcasting, we derive several theoretical properties for the average access time in a multiple channel environment. In light of the theoretical results, we develop an efficient heuristic algorithm to generate broadcast programs, which are designed for the environments with replication. Our experimental results show that the proposed algorithm is able to obtain solution broadcast programs of very high quality.
An evaluation of clinical accuracy of the EasyTouch blood uric acid self-monitoring system
(2005-03-01)
Dai, KS
;
Tai, DY
;
Ho, P
;
Chen, CC
;
Peng, WC
Objectives: Self-monitoring blood uric acid device is an important tool for patients to efficiently monitor their blood uric acid concentrations. The objective of the present study was to evaluate the accuracy of EasyTouch uric acid monitoring system. Design and methods: Capillary blood uric acid concentrations measured using EasyTouch and the reference values obtained from COBAS MIRA were performed in the Department of Laboratory Medicine, Wei-Gong Memorial Hospital. Results were evaluated using (1) linear regression analysis, (2) percentage of readings within a defined range of deviation from the reference value, and (3) coefficients of variation (CVs) calculated from 60 measurements in series. Results: The window of the 177 EasyTouch readings covered a wide range from 0.1785 to 0.6367 mmol/L (3-10.7 mg/dL). Linear regression analysis yielded a regression slope of 0.975, an intercept of 0.0118 mmol/L and an R-2 of 0.8966. Of the EasyTouch readings, 64 (36.2%), 61 (34.5%), 34 (19.2%), 9 (5.08%), and 9 (5.08%) were within the intervals of <5%, 5-10%, 10-15%, 15-17%, and >17%, respectively, of the reference values. Further analysis for the performance of each lot of strips showed that both coefficients of correlation and the percentages of readings within the CLIA's criterion (+/-17%), respectively, were in a narrow range from 0.8777 to 0.9541 and from 92.1% to 100%. The CVs for the seven lots of strips (lot I to lot 7) ranged from 2.93% to 6.33%, 3.2% to 5.9%, 3.64% to 7.0%, 2.84% to 7.6%, 2.68% to 5.42%, 3.03% to 6.93%, and 3.18% to 5.17%, respectively. Conclusion: EasyTouch is an acceptable diagnostic device which provides accurate uric acid measurements. (C) 2004 The Canadian Society of Clinical Chemists. All rights reserved.
Design and performance studies of an adaptive cache retrieval scheme in a mobile computing environment
(2005-01-01)
Peng, WC
;
Chen, MS
;
資訊工程學系
;
Department of Computer Science
In a mobile computing system, as users move to a new service area, the new server is usually considered to take over the execution of running programs for mobile users from the previous server so as to reduce the communication overhead of a mobile system. This procedure is referred to as service handoff. Note that when service handoff occurs, the new server will lose its advantage for cache access. To remedy this, we explore in this paper several cache retrieval schemes to improve the efficiency of cache retrieval. In particular, we analyze the impact of using a coordinator buffer to improve the overall performance of cache retrieval. Moreover, in light of the properties of transactions (i.e., temporal locality of data access among transactions), we devise a Dynamic and Adaptive cache Retrieval scheme (DAR) that can utilize proper cache methods according to some specific criteria to deal with the service handoff situation in a mobile computing environment. Performance of these cache retrieval schemes is analyzed and a system simulator is developed to validate our results. We devise a systematic procedure for determining the optimal operating points of DAR. Our experimental results show that by adaptively adopting the advantages of different cache retrieval methods, DAR significantly outperforms other schemes and is particularly effective for a mobile computing environment.
Efficient in-network moving object tracking in wireless sensor networks
(2006-08-01)
Lin, CY
;
Peng, WC
;
Tseng, YC
;
資訊工程學系
;
Department of Computer Science
The rapid progress of wireless communication and embedded microsensing MEMS technologies has made wireless sensor networks possible. In light of storage in sensors, a sensor network can be considered as a distributed database, in which one can conduct in-network data processing. An important issue of wireless sensor networks is object tracking, which typically involves two basic operations: update and query. This issue has been intensively studied in other areas, such as cellular networks. However, the in-network processing characteristic of sensor networks has posed new challenges to this issue. In this paper, we develop several tree structures for in-network object tracking which take the physical topology of the sensor network into consideration. The optimization process has two stages. The first stage tries to reduce the location update cost based on a deviation-avoidance principle and a highest-weight-first principle. The second stage further adjusts the tree obtained in the first stage to reduce the query cost. The way we model this problem allows us to analytically formulate the cost of object tracking given the update and query rates of objects. Extensive simulations are conducted, which show a significant improvement over existing solutions.
Enhanced performance of an InGaN-GaN light-emitting diode by roughening the undoped-GaN surface and applying a mirror coating to the sapphire substrate
(2006-05-01)
Peng, WC
;
Wu, YS
;
材料科學與工程學系
;
Department of Materials Science and Engineering
An InGaN-GaN light-emitting diode (LED) with a roughened undoped-GaN surface and a silver mirror on the sapphire substrate was fabricated through a double transfer method. It was found that, at an injection current of 20 mA, its luminance intensity was 100% larger than conventional LEDs. Its output power was 49% larger than conventional LEDs. (c) 2006 American Institute of Physics.
Exploring regression for mining user moving patterns in a mobile computing system
(2005)
Hung, CC
;
Peng, WC
;
Huang, JL
;
資訊工程學系
;
Department of Computer Science
In this paper, by exploiting the log of call detail records, we present a solution procedure of mining user moving patterns in a mobile computing system. Specifically, we propose algorithm LS to accurately determine similar moving sequences from the log of call detail records so as to obtain moving behaviors of users. By exploring the feature of spatial-temporal locality, we develop algorithm TC to group call detail records into clusters. In light of the concept of regression, we devise algorithm MF to derive moving functions of moving behaviors. Performance of the proposed solution procedure is analyzed and sensitivity analysis on several design parameters is conducted. It is shown by our simulation results that user moving patterns obtained by our solution procedure are of very high quality and in fact very close to real user moving behaviors.
Performance of InGaN-GaN LEDs fabricated using glue bonding on 50-mm Si substrate
(2006-01-01)
Peng, WC
;
Wu, YS
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Vertical InGaN-GaN light-emitting diodes (LEDs) epitaxial films were successfully fabricated on a 50-mm Si substrate using glue bonding and laser liftoff technology. A high-temperature stable organic film, rather than a solder metal, was used as the bonding agent. It was found that the light output of the vertical InGaN LED chip exceeded that of the conventional sapphire-substrate LEDs by about 20% at an injection current of 20 mA. The vertical InGaN LEDs operated at a much higher injection forward current (280 mA) than sapphire-substrate LEDs (180 mA). The radiation pattern of the vertical InGaN LEDs is more symmetrical than that of the sapphire-substrate LEDs. Furthermore, the vertical InGaN LEDs remain highly reliable after 1000 h of testing.
Query processing in a mobile computing environment: Exploiting the features of asymmetry
(2005-07-01)
Peng, WC
;
Chen, MS
;
資訊工程學系
;
Department of Computer Science
With the cutting edge technology advance in wireless and mobile computers, the query processing in a mobile environment involves join processing among different sites which include static servers and mobile computers. Because of the need for energy saving and also the presence of asymmetric features in a mobile computing environment, the conventional query processing for a distributed database cannot be directly applied to a mobile computing system. In this paper, we first explore three asymmetric features of a mobile environment. Then, in light of these features, we devise query processing methods for both join and query processing. Intuitively, employing semijoin operations in a mobile computing environment is able to further reduce both the amount of data transmission and energy consumption. A semijoin which is initiated by a mobile computer ( respectively, the server) and is beneficial to reduce the cost of a join operation is termed a mobile- initiated or MI ( respectively, server- initiated or SI) profitable semijoin. According to those asymmetric features of a mobile computing system, we examine three different join methods and devise some specific criteria to identify MI/ SI profitable semijoins. For query processing, which refers to the processing of multijoin queries, we develop three query processing schemes. In particular, we formulate the query processing in a mobile computing system as a two- phase query processing procedure that can determine a join sequence and interleave that join sequence with SI profitable semijoins to reduce both the amount of data transmission and energy consumption. Performance of these join and query methods is comparatively analyzed and sensitivity analysis on several parameters is conducted. Furthermore, we develop a systematic procedure to derive the characteristic functions of MI and SI profitable semijoins. It is noted that, given some system parameters, those characteristic functions are very important in determining which join method is the most appropriate one to employ in that configuration. It is shown by our simulation results that, by exploiting the three asymmetric features, these characteristic functions are very powerful in reducing both the amounts of energy consumption and data transmission incurred and can lead to the design of an efficient and effective query processing procedure for a mobile computing environment.