Browsing by Author "Huang, Yu-Wen"

Now showing 1 - 15 of 15

A Bandwidth Efficient Pairing Strategy for the MIMO-OFDM Based WLANs
(2009)
Lee, Tsern-Huei
;
Hsieh, Jing-Rong
;
Huang, Ming-Chih
;
Huang, Yu-Wen
;
電信工程研究所
The advanced MIMO (multiple-input multiple-output) system can provide higher capacity gain or higher diversity gain in modern wireless networks. The capacity gain is achieved by interference cancelation technique to fully utilize the spatial degree of freedom. In a multiuser wireless system, the increased degrees of freedom provide the chance to select multiple wireless stations (STAs) to maximize the throughput. In this paper, we consider a scenario where the access point (AP) equipped with two antennas to simultaneously communicate with two STAs, each with single antenna. After obtaining the statuses of the size of buffered traffic and the achievable transmission rate, the AP should pair compatible STAs to minimize the loss of spatial degree of freedom. Therefore, three pairing algorithms are proposed and are evaluated through computer simulations. The algorithms have much less implementation complexity than the brute force pairing algorithm and achieve satisfactory performance of throughput.
A High-throughput Cell-based Screening for L858R/T790M Mutant Epidermal Growth Factor Receptor Inhibitors
(2012-01-01)
Lin, Wen-Hsing
;
Song, Jen-Shin
;
Lien, Tzu-Wen
;
Chang, Chun-Yu
;
Wu, Szu-Huei
A high-throughput 32D(L858R/T790M) cell-based assay to identify inhibitors of the L858R/T790M mutant epidermal growth factor receptor (EGFR) pathway was established. After screening, ten hits from among 60,000 compounds in our in-house compound library were initially identified. In the secondary assays, one hit, 1-[2-(decyloxy)-2-oxoethyl]-3-methyl-2-[(4-methylphenoxy) methyl]-1H-benzimidazol-3-ium, was confirmed to directly inhibit the kinase activity of recombinant L858R/T790M EGFR and the phosphorylation of EGFR-L858R/T790M in gefitinib-resistant H1975 cells. Thus, this high-throughput assay system may be useful for identifying novel inhibitors which suppress mutant EGFR-T790M signalling and for overcoming T790M-mediated acquired resistance for future anticancer drug discovery.
A Low Overhead Queue Status Report Scheme for QoS Support in WLANs
(2009)
Lee, Tsern-Huei
;
Huang, Yu-Wen
;
Yang, Chun-Chieh
;
電信工程研究所
;
Institute of Communications Engineering
HCF Controlled Channel Access (HCCA), defined in the IEEE 802.11e document, provides a sample scheduler to allocate transmission opportunity (TXOP) to QoS-aware stations (QSTAs). Since the calculation of TXOP duration is based on mean data rate, it is efficient for constant bit rate (CBR) traffic. For variable bit rate (VBR) traffic, however, delay bound of some admitted traffic flows may be violated. Several previous works suggested that, through reporting queue status to schedulers, each QSTA can be allocated sufficient transmission opportunity (TXOP) for its buffered packets to meet delay bound requirement. However, timely queue status reports may cause considerable overheads and lead to inefficient bandwidth utilization. In this paper, we propose a low overhead queue status report scheme based on multi-polling technique and earliest deadline first policy (EDF) to provide QoS support. Simulation results show that our proposed scheme can not only meet the QoS requirements but also manage the bandwidth more efficiently than previous works.
Amphiregulin promotes cisplatin chemoresistance by upregulating ABCB1 expression in human chondrosarcoma
(2020-05-31)
Huang, Yu-Wen
;
Lin, Chih-Yang
;
Tsai, Hsiao-Chi
;
Fong, Yi-Chin
;
Han, Chien-Kuo
Chondrosarcomas are well known for their resistance to chemotherapeutic agents, including cisplatin, which is commonly used in chondrosarcomas. Amphiregulin (AR), a ligand of epidermal growth factor receptor (EGFR), plays an important role in drug resistance. We therefore sought to determine the role of AR in cisplatin chemoresistance. We found that AR inhibits cisplatin-induced cell apoptosis and promotes ATP-binding cassette subfamily B member 1 (ABCB1) expression, while knockdown of ABCB1 by small interfering RNA (siRNA) reverses these effects. High phosphoinositide 3-kinase (PI3K), Akt and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kappa B) phosphorylation levels were observed in cisplatin-resistant cells. Pretreating chondrosarcoma cells with PI3K, Akt and NF-kappa B inhibitors or transfecting the cells with p85, Akt and p65 siRNAs potentiated cisplatin-induced cytotoxicity. In a mouse xenograft model, knockdown of AR expression in chondrosarcoma cells increased the cytotoxic effects of cisplatin and also decreased tumor volume and weight. These results indicate that AR upregulates ABCB1 expression through the PI3K/Akt/NF-kappa B signaling pathway and thus contributes to cisplatin resistance in chondrosarcoma.
Design and Evaluation of a High Throughput MAC with QoS Guarantee for Wireless LANs
(2009)
Kuo, Yaw-Wen
;
Lee, Tsern-Huei
;
Huang, Yu-Wen
;
Hsieh, Jing-Rong
;
電信工程研究所
The IEEE 802.11e and the IEEE 802.11n focus on quality of service (QoS) and enhancements for high throughput respectively. Modern wireless LAN (WLAN) products should integrate both features. This paper presents a design of a high throughput MAC with QoS guarantee which combines the Hybrid Coordination Function (HCF) of the 802.11e with the frame aggregation technique in the 802.11n. The basic idea of the design is to improve the throughput of best-effort traffic under the constraint that QoS is just met for real-time traffic. Simulation results show that the proposed MAC has high channel utilization and the delay of best-effort traffic is also reduced.
Gaussian approximation based admission control for variable bit rate traffic in IEEE 802.11e WLANs
(2007)
Huang, Yu-Wen
;
Lee, Tsern-Huei
;
Hsieh, Jing-Rong
;
電信工程研究所
;
Institute of Communications Engineering
For QoS requirements of real-time traffic, IEEE 802.11 working group introduces a QoS-aware channel access mechanism, called Hybrid Coordination Function (HCF), which consists of contention-based Enhanced Distributed Channel Access (EDCA) and contention-free HCF Controlled Channel Access (HCCA). The TXOP allocation and the admission control units of the HCCA reference scheduler are only appropriate for constant bit rate (CBR) flows. It may result in serious packet loss for variable bit rate (VBR) flows. In this paper, we propose a simple admission control algorithm which adopts Gaussian distribution to approximate VBR traffic. Numerical results obtained from computer simulations show that our proposed algorithm can effectively and efficiently allocate Transmission Opportunity (TXOP) durations to QoS-enhanced stations (QSTAs) to guarantee a predefined packet loss probability. Moreover, our proposed scheme can easily handle multiple VBR flows of the same QSTA to get the advantage of multiplexing gain.
On the relationship between the sequence conservation and the packing density profiles of the protein complexes
(2013-07-01)
Chang, Chih-Min
;
Huang, Yu-Wen
;
Shih, Chien-Hua
;
Hwang, Jenn-Kang
;
生物資訊及系統生物研究所
We have recently showed that the weighted contact number profiles (or the packing density profiles) of proteins are well correlated with those of the corresponding sequence conservation profiles. The results suggest that a protein structure may contain sufficient information about sequence conservation comparable to that derived from multiple homologous sequences. However, there are ambiguities concerning how to compute the packing density of the subunit of a protein complex. For the subunits of a complex, there are different ways to compute its packing density - one including the packing contributions of the other subunits and the other one excluding their contributions. Here we selected two sets of enzyme complexes. Set A contains complexes with the active sites comprising residues from multiple subunits, while set B contains those with the active sites residing on single subunits. In Set A, if the packing density profile of a subunit is computed considering the contributions of the other subunits of the complex, it will agree better with the sequence conservation profile. But in Set B the situations are reversed. The results may be due to the stronger functional and structural constraints on the evolution processes on the complexes of Set A than those of Set B to maintain the enzymatic functions of the complexes. The comparison of the packing density and the sequence conservation profiles may provide a simple yet potentially useful way to understanding the structural and evolutionary couplings between the subunits of protein complexes. Proteins 2013; 81:1192-1199. (c) 2013 Wiley Periodicals, Inc.
Optimal Resource Allocation for Increasing Strictly Concave Utility Functions in Wireless Networks
(2012-03-01)
Lee, Tsern-Huei
;
Huang, Yu-Wen
;
Chen, Chien-Nan
;
傳播研究所
;
Institute of Communication Studies
Utility functions are widely used to model user-perceived service quality. For elastic traffic, the utility function is often concave. An elastic allocation (EA) algorithm has recently been proposed to maximize the total utility obtained by users, assuming resource is infinitesimally divisible and queues are constantly backlogged. We found that the EA algorithm is not always optimal. In fact, the solution it obtains can be infeasible. In this paper, we present a modified EA algorithm that is guaranteed to find the optimal solution under the same assumptions. The result is generalized for a system where queues are generally backlogged. In a real system, there is normally a basic unit for resources. Therefore, we further extend the designs to such a system for both constantly backlogged and generally backlogged queues. To reduce computational complexity, we also propose suboptimal resource allocation algorithms. Simulations are conducted to evaluate the proposed algorithms in terms of utility sum and execution time. Results show that our proposed algorithms perform better than previous works. Moreover, the performances of the proposed suboptimal algorithms are close to those of the optimal algorithms.
Quality of service guarantee for real-time VBR traffic flows with different delay bound and loss probability requirements in WLANs
(2013)
Lee, Tsern-Huei
;
Huang, Yu-Wen
;
傳播研究所
;
Institute of Communication Studies
The medium access control of IEEE 802.11e defines a novel coordination function, namely hybrid coordination function (HCF), which allocates transmission opportunity (TXOP) to stations taking their quality of service (QoS) requirements into account. However, the reference TXOP allocation scheme of HCF controlled channel access, a contention-free channel access function of HCF, is only suitable for constant bit rate traffic. For variable bit rate (VBR) traffic, serious packet loss may occur. In this article, we generalize the reference design with an efficient TXOP allocation algorithm, a multiplexing mechanism, and an associated admission control unit to guarantee QoS for VBR flows with different delay bound and packet loss probability requirements. We define equivalent flows and aggregate packet loss probability to take advantage of both intra-flow and inter-flow multiplexing gains so that high bandwidth efficiency can be achieved. Moreover, the concept of weighted-loss fair service scheduling is adopted to allocate the aggregate TXOP to individual flows. From numerical results obtained by computer simulations, we found that our proposed scheme meets QoS requirements and results in much higher bandwidth efficiency than previous algorithms.
Real-Time and Label-Free Detection of the Prostate-Specific Antigen in Human Serum by a Polycrystalline Silicon Nanowire Field-Effect Transistor Biosensor
(2013-08-20)
Huang, Yu-Wen
;
Wu, Chung-Shu
;
Chuang, Cheng-Keng
;
Pang, See-Tong
;
Pan, Tung-Ming
In this research, we used a polycrystalline silicon nanowire field-effect transistor (poly-Si NWFET) as a biosensor that employs the sidewall spacer technique instead of an expensive electron beam lithography method. When compared with commercial semiconductor processes, the sidewall spacer technique has the advantages of simplicity and low cost. hi this study, we employed a novel poly-Si NWFET device for real-time, label-free, and ultrahigh-sensitivity detection of prostate-specific antigen (PSA) in human serum. Since serum proteome is very complex containing high levels of salts and other interfering compounds, we hereby developed a standard operating procedure for real-sample pretreatment to keep a proper pH value and ionic strength of the desalted serum and also utilized Tween 20 to serve as the passivation agent by surface modification on the NWFET to reduce nonspecific binding for medical diagnostic applications. We first modified 3-aminopropyltriethoxysilane on the surface of a poly-Si nanowire device followed by glutaraldehyde functionalization, and the PSA antibodies were immobilized on the aldehyde terminal. While PSA was prepared in the buffers to maintain an appropriate pH value and ionic strength, the results indicated that the sensor could detect trace PSA at less than 5 fg/mL in a microfluidic channel. The novel poly-Si NWFET is developed as a diagnostic platform for monitoring prostate cancer and predicting the risk of early biochemical relapse.
Regioselective and stereoselective benzylidene installation and one-pot protection of D-mannose
(2013)
Patil, Pratap S.
;
Lee, Chia-Chen
;
Huang, Yu-Wen
;
Zulueta, Medel Manuel L.
;
Hung, Shang-Cheng
Oligosaccharide syntheses are an important source of well-defined sugar constructs particularly needed for the evaluation of structure-activity relationships. The chemical assembly of oligosaccharides requires several building blocks, that is, glycosyl donors and acceptors, which are prepared in multistep processes and in a generally tedious and time-consuming manner. Having developed one-pot procedures meant to minimise the effort in sugar building block preparation, we tackled herein the one-pot preparation of fully protected and 2-, 3-, 4-, and 6-alcohol derivatives of D-mannose, a widely distributed monosaccharide. As a consequence of the hydroxyl group pattern of D-mannose, regioselective and stereoselective benzylide-nations were developed and later seamlessly utilised as the first transformation in the one-pot procedure.
Resource Allocation Achieving High System Throughput with QoS Support in OFDMA-Based System
(2012-03-01)
Lee, Tsern-Huei
;
Huang, Yu-Wen
;
傳播研究所
;
Institute of Communication Studies
In this paper, we present a resource allocation algorithm for OFDMA-based systems which handles both real-time and non-real-time traffic. For real-time traffic, the QoS requirements are specified with delay bound and loss probability. The resource allocation problem is formulated as one which maximizes system throughput subject to the constraint that the bandwidth allocated to a flow is no less than its minimum requested bandwidth, a value computed based on loss probability requirement and running loss probability. A user-level proportional-loss scheduler is adopted to determine the resource share for flows attached to the same subscriber station (SS). In case the available resource is not sufficient to provide every flow its minimum requested bandwidth, we maximize the amount of real-time traffic transmitted subject to the constraint that the bandwidth allocated to an SS is no greater than the sum of minimum requested bandwidths of all flows attached to it. Moreover, a pre-processor is added to maximize the number of real-time flows attached to each SS that meet their QoS requirements. We show that, in any frame, the proposed proportional-loss scheduler guarantees QoS if there is any scheduler which guarantees QoS. Simulation results reveal that our proposed algorithm performs better than previous works.
Sequence Conservation, Radial Distance and Packing Density in Spherical Viral Capsids
(2015-07-01)
Chang, Chih-Min
;
Huang, Yu-Wen
;
Lee, Chi-Wen
;
Huang, Tsun-Tsao
;
Shih, Chung-Shiuan
The conservation level of a residue is a useful measure about the importance of that residue in protein structure and function. Much information about sequence conservation comes from aligning homologous sequences. Profiles showing the variation of the conservation level along the sequence are usually interpreted in evolutionary terms and dictated by site similarities of a proper set of homologous sequences. Here, we report that, of the viral icosahedral capsids, the sequence conservation profile can be determined by variations in the distances between residues and the centroid of the capsid - with a direct inverse proportionality between the conservation level and the centroid distance - as well as by the spatial variations in local packing density. Examining both the centroid and the packing density models against a dataset of 51 crystal structures of nonhomologous icosahedral capsids, we found that many global patterns and minor features derived from the viral structures are consistent with those present in the sequence conservation profiles. The quantitative link between the level of conservation and structural features like centroid-distance or packing density allows us to look at residue conservation from a structural viewpoint as well as from an evolutionary viewpoint.
The conservation profile of a protein bears the imprint of the molecule that is evolutionarily coupled to the protein
(2015-08-01)
Huang, Yu-Wen
;
Chang, Chih-Min
;
Lee, Chi-Wen
;
Hwang, Jenn-Kang
;
生物資訊及系統生物研究所
The conservation profile of a protein is a curve of the conservation levels of amino acids along the sequence. Biologists are usually more interested in individual points on the curve (namely, the conserved amino acids) than the overall shape of the curve. Here, we show that the conservation curves of proteins bear the imprints of molecules that are evolutionarily coupled to the proteins. Our method is based on recent studies that a sequence conservation profile is quantitatively linked to its structural packing profile. We find that the conservation profiles of nucleic acid (NA) binding proteins are better correlated with the packing profiles of the protein-NA complexes than those of the proteins alone. This indicates that a nucleic acid binding protein evolves to accommodate the nucleic acid in such a way that the residues involved in binding have their conservation levels closely coupled with the specific nucleotides. Proteins 2015; 83:1407-1413. (c) 2015 Wiley Periodicals, Inc.
To Piggyback Or Not to Piggyback Acknowledgments?
(2010)
Lee, Tsern-Huei
;
Kuo, Yaw-Wen
;
Huang, Yu-Wen
;
Liu, Yung-Hsiang
;
電信工程研究所
Piggyback is an effective way to reduce the MAC protocol overhead of wireless networks. This paper considers the physical data rate and transmission bit error to derive the criterion of piggyback. Numerical results show that the improvement of piggyback can reach 40% for some cases. For given the bit error rate and the data rate, we also provide the criterion for every combination in a table.