Browsing by Author "Chen, KL"

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A CORDIC processor with efficient table-lookup schemes for rotations & on-line scale factor compensations
(2005)
Chih, JC
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Chen, KL
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Chen, SG
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
In this paper, we improve our previous efficient CORDIC processor design. The improvements consist of two parts: (1) an improved table-lookup rotation scheme with a smaller table than before, and (2) a new efficient on-line table-lookup scheme for scale-factor computations and compensations which is better than the previous non-online design. Combining the improvements with the original efficient rotation angle recoding algorithm and leading-one (or zero) bit detection (for skipping redundant rotations), we obtain a lowiteration and low-complexity COREDC processor architecture. The design is more efficient than the current designs, especially in the iteration count. Simulation shows that for n-bit results, about only n/4 iterations are required. We also designed a 16-bit CORDIC processor based on 0.25 mu m UMC process. Its averaged iteration count is only 4.4 including rotation and scale factor compensations, with a total gate count of 5742 and a maximum operating frequency of 250MHz.
A practical implementation of the incapability index C-pp
(2002-12-01)
Pearn, WL
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Chen, KL
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Chen, KS
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工業工程與管理學系
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Department of Industrial Engineering and Management
Process capability index C-pp has been introduced to measure process performance. In practice, since sample data must be collected in order to calculate the index value, then a great degree of uncertainty may be introduced into capability assessments due to sampling errors. In current practice, the practitioners would simply look at the index value calculated from the sample data then make a conclusion on whether the given process meets the capability requirement. This approach is not reliable since the sampling errors are ignored. In this paper, we take into account the sampling errors and develop a simple procedure using the UMVUE (uniformly minimum variance unbiased estimator) of C-pp, for practitioners to use in determining whether a process meets the capability requirement. The decisions made based on the proposed procedure are, of course, more reliable.
Contract manufacturer selection by using the process incapability index C-pp
(2005-09-01)
Chen, KS
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Chen, KL
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Li, RK
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工業工程與管理學系
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Department of Industrial Engineering and Management
In the competitive global business environment, enterprises should effectively respond to and satisfy customer needs. Outsourcing manufacturing is an effective method of adjusting the flexibility of production capability. To ensure final product quality, evaluating and selecting a contract manufacturer is essential. Process capability indices are extensively adopted in manufacturing to determine whether a process meets capability requirements. This study attempts to determine the score index R-i and then apply it to assess the process performance of contract manufacturer by using the process incapability index C-pp. The formulae for C-pp and R-i are simple to understand and to apply. The procedure developed in this paper is also an easy and convenient tool for practitioners to assess contract manufacturer quality performance and make more reliable decisions regarding contract manufacturer.
Design of an efficient variable-length FFT processor
(2004)
Hung, CP
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Chen, SG
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Chen, KL
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
In this paper, we propose an efficient variable-length FFT processor architecture suitable for multi-mode and multi-standard OFDM communication systems. The FFT processor is based on radix-2(2) DIF FFT algorithm and also supports non-power-of-4 FFT computation. The design contains an efficient processing element (PE), which can execute radix-2(2) butterfly (BF) operations, as well as radix-2 BF operations. Moreover, in order to achieve high-performance variable-length FFT operations and data accesses, an efficient variable-length address generator and twiddle factor generator are designed. The design has the merits of low complexity and high speed performance. The designs consider seven different FFT lengths including 64, 256, 512, 1024, 2048, 4096, and 8192 points, which cover all the required FFT lengths by 802.1.1a, 802.16a, DAB, DVB-T, VDSL and ADSL.
Suppliers capability and price analysis chart
(2005-12-18)
Chen, KL
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Chen, KS
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Li, RK
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工業工程與管理學系
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Department of Industrial Engineering and Management
To remain competitive in customer-oriented economics, the major parties in the supply chain should be integrated and managed effectively to respond to customer needs. Thus, the efficiency of the entire supply chain is a main concern, and is determined by the members of that supply chain. Partner selection thus becomes one of the key steps in supply chain construction. Given buyer-supplier information asymmetry, obtaining complete information from suppliers is difficult, since some supplier attributes cannot be definitely and quantitatively measured. This study establishes a suppliers capability and price analysis chart (SCPAC) focused on the case where the specification limits are symmetric about the target for evaluating supplier performance which applies the process incapability index C-pp introduced by Greenwich and Jahr-Schaffrath (International Journal of Quality & Reliability Management 12 (1995) 58) to measure supplier quality performance and the price index I-p is proposed here to display the difference between budget and component price. Practitioners can instantly and visually obtain information based on the locations of suppliers and price indices on SCPAC. SCPAC also provides clear directions for quality improvement, such as process accuracy and precision. SCPAC thus is an effective and efficient method for evaluating suppliers, which can simplify supplier evaluation, facilitate their effective visual selection, and provide insights into the process situation of suppliers who can become technological innovation partners. (c) 2004 Published by Elsevier B.V.