Browsing by Author "Liu, YH"

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A distributed buffer management approach supporting IPv6 mobility
(2004)
Liu, YH
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Chen, YC
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資訊工程學系
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Department of Computer Science
In wireless local area networks (WLANs), mobility support is essential for providing seamless services. The current Mobile IP standard suffers several problems, especially for accommodating real-time media applications. Most of the existing studies focus on improving the performance between the Home Agent (HA) and Foreign Agent (FA). In this work, we propose a buffer management approach to enhance the performance between the Mobility Agent (HA or FA) and the Mobile Node (MN). The proposed scheme deals with the packet delivery between MAs and MNs in Layer 2. Through the simulation, we show that our scheme improves TCP throughput as well as reduces the UDP packet loss rate. Moreover, it is implementation feasible in both IPv4 and IPv6, and suitable for supporting Quality of Service (QoS).
A necessary and sufficient condition for minimizing a convex Frechet differentiable function on a certain hyperplane
(2001-01-01)
Li, HL
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Liu, YH
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Matache, V
;
Yu, PL
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資訊管理與財務金融系註：原資管所+財金所
A convex Frechet differentiable function is minimized subject to a certain hyperplane at a point if the function is minimized in all directions which are defined by a finite set of vectors. The proposed approach is different from the Lagrange multiplier approach. At the end of this paper, a linear program is formulated to solve the case when the above given convex function is quadratic. (C) 2001 Academic Press.
Almost automatic method for reconstruction 3D geometric model of the left ventricle from 3D+1D precordial echocardiogram
(2001-01-01)
Ching, YT
;
Liu, YH
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Chang, CL
;
Chen, JSJ
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資訊工程學系
Echocardiography is the most convenient means for both physicians and patients for heart disease diagnosis. The 3D+1D echocardiogram. provides important information for evaluation of the 3D heart function such as the ejection fraction or wall motion. The most basic task to evaluate such functions of a heart is to segment left ventricles and reconstruct the the 3D geometric model of left ventricle from a set of echocardiographic images. Since there are many images involved, the method should not need too many user assists. In this work, we design a method for reconstructing the left ventricles with very few user assists.
An alternative formulation for certain fuzzy set-covering problems
(2005-08-01)
Chiang, CI
;
Hwang, MJ
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Liu, YH
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資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
The fuzzy set-covering model using auxiliary 0-1 variables and a system of inequalities was developed by Hwang et al. [1]. By taking logarithm of the inequalities constraints and using the nature of the Boolean variables of this fuzzy set covering model, a simplified model is obtained. (c) 2005 Elsevier Ltd. All rights reserved.
Equivalent double-loop networks
(2000-12-01)
Huang, SH
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Hwang, FK
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Liu, YH
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應用數學系
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Department of Applied Mathematics
Hwang and Xu defined equivalent double-loop networks and gave one such result showing that the L-shapes of the two equivalent networks: are recombinations of three rectangles. Recently, Rodseth gave an elegant algebraic theorem for equivalent multi-loop networks. We show that its double-loop version yields equivalent networks of the 3-rectangle version. We also show that other seemingly different geometric recombinations also all turn out to be special cases of the 3-rectangle version.
Finding the mitral annular lines from 2-D+1-D precordial echocardiogram using graph-search technique
(2004-03-01)
Ching, YT
;
Chen, SJ
;
Chang, CL
;
Lin, CY
;
Liu, YH
The apical four-chamber view echocardiogram collected by a transthoracic transducer can be used to evaluate the left ventricle volume. In the diastole, the left ventricle and left atrium become one chamber. In this case, the left ventricle and left atrium need to be separated using a "mitral annular line" so the volume of the left ventricle can be estimated. In this paper, a nearly automatic method for identifying the mitral annular lines from two-dimensional (2-D) + one-dimensional (1-D) precordial four-chamber view echocardiogram is presented. This method employs the optical flow technique and graph-search approach. The mitral annular line sequence is found by finding the shortest path in a weighted directed graph. The vertices in the graph are candidates for the mitral annular lines. The weights on the directed edges are determined using the optical flow technique. The proposed method requires only a physician to provide, a point that is always in the left ventricular chamber. Experimental results show that the average error for the left ventricle volume obtained based on the computed mitral annular lines is 3%.
Implementation of ZVT soft switching technique in a single-phase PFC rectifier for server power supply
(2000)
Liu, HF
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Liu, YH
;
Tzou, YY
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電控工程研究所
;
Institute of Electrical and Control Engineering
This of paper presents the design and implementation of a zero-voltage-transition power factor correction (PFC) converter which can achieve high power factor, low harmonic distortion, and high efficiency. Zero-voltage-transition soft-switching technique has been applied to reduce the switching losses of the auxiliary switching circuit for a single-phase sc-de converter with unit power factor. Its kW, 200 kH5 soft-switching single-phase PFC converter has operation principle and design equations have been given. A 2 been constructed. An efficiency of 94% at rated output has been measured. Experimental results show the developed design procedure for the ZVT soft-switching PFC converter can achieve unit power factor, high efficiency, and low EMI.
Stable organic blue-light-emitting devices prepared from poly[spiro(fluorene-9,9'-xanthene)]
(2005-11-29)
Tseng, YH
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Shih, PI
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Chien, CH
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Dixit, AK
;
Shu, CF
A short, efficient synthetic route has been developed for the preparation of 2,7-dibromospiro-[fluorene-9,9'-(2',7'-di-n-octyloxyxanthene)], which was subsequently polymerized with the corresponding diborolane through Suzuki coupling to afford a fluorene-based homopolymer, PSFX, that contains a spiroxanthene group functionalized on the C-9 position of each fluorene repeat unit. Single-crystal X-ray diffraction analysis of the dibromo monomer revealed that the spiro-fused fluorene and xanthene moieties lie perpendicular to one another. As a consequence of the incorporation of the spiro pendant group, PSFX possesses a high glass transition temperature and good thermal stability while displaying its stable blue emission in the solid state. A light-emitting diode device prepared using PSFX as the emitting layer exhibits an efficient, stable blue emission; it has a turn-on voltage of 6 V and a maximum external quantum efficiency of 1.74% ph/el. Even when the brightness was increased up to 10(3) cd/m(2) (ca. 11 V), the CIE color coordinates of the resulting EL spectrum remained in the deep-blue region (0.15, 0.07) and the device's efficiency was 1.33% ph/el.