• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.7 s.98
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• pp.697-708
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• 2005

The forward link of the 3G CDMA system may become limited under the increasing of the number of users. The conventional channelization code, Walsh code, has not enough sizes f3r much possible users, therefore, the quasi orthogonal function(QOF), which process optimal crosscorrelation with Walsh code, is considered. In this paper, we investigate quasi orthogonal function on Jacket matrices, which can lead lower correlations values and better performance in 3G CDMA system. Moreover, to simplify the detector and improve the BER performance, a novel detection for QOF CDMA system is proposed. Finally, the simple recursive generation of the bent sequences for QOF mask function is discussed.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.3
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• pp.9-18
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• 2001

In this paper, we present the joint symbol detection and channel estimation for an orthogonal frequency division multiplexing (OFDM) system in fading channels. The proposed methods are based on decision-directed channel estimation (DDCE) method and their symbol detection is achieved by using Viterbi algorithm. This Viterbi decision-directed channel estimation (VDDCE) method tracks time-varying channels and detects a maximum likelihood symbol sequence. Recursive Viterbi decision-directed channel estimation (RVDDCE) method based on VDDCE method is proposed to shorten the detecting depth. In this method, channel estimate and Viterbi processing are recursively performed every interval of training symbol. Also, average chann'el estimation (ACE) technique to reduce the effect of additive white Gaussian noise (AWGN) is applied VDDCE method and RVDDCE method. These proposed methods arc demonstrated by computer simulation.

• Bulletin of the Korean Mathematical Society
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• v.46 no.2
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• pp.331-346
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• 2009

Let ${\alpha}$ = (${\alpha}_1,\;{\alpha}_2$,...) and ${\beta}$ = (${\beta}_1,\;{\beta}_2$,...) be two sequences with ${\alpha}_1$ = ${\beta}_1$ and k and n be natural numbers. We denote by $A^{(k,{\pm})}_{{\alpha},{\beta}}(n)$ the matrix of order n with coefficients ${\alpha}_{i,j}$ by setting ${\alpha}_{1,i}$ = ${\alpha}_i,\;{\alpha}_{i,1}$ = ${\beta}_i$ for 1 ${\leq}$ i ${\leq}$ n and $${\alpha}_{i,j}=\{{\alpha}_{i-1,j-1}+{\alpha}_{i-1,j}\;if\;j{\equiv}$$2,3,4,..., k + 1 (mod 2k) $$\{{\alpha}_{i-1,j-1}-{\alpha}_{i-1,j}\;if\;j{\equiv}$$ k + 2,..., 2k + 1 (mod 2k) for 2 ${\leq}$ i, j ${\leq}$ n. The aim of this paper is to study the determinants of such matrices related to certain sequence ${\alpha}$ and ${\beta}$ and some natural numbers k.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.1
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• pp.5-11
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• 2002

Active vibration control of intelligent laminated composite plates is performed experimental1y Laminated composite place is modeled by the system identification method. For the system identification process, the laminated composite place is excited by two piezoelectric actuators with PRBS signals. At the same time, the displacement of the laminated composite plate is measured by a gap sensor. From these excited PRBS signals and the measured displacement sequence, system parameters of the laminated composite plate are estimated using a recursive prediction error method. Model of the laminated composite plate with two piezoeletric actuators is assumed to be the form of ARMAX. From the estimated ARHMAX model, a state space equation of the observable canonical form is obtained. With this state space equation, a controller and an observer for active vibration control is designed using the optimal control method. Controller and observer are implemented on a digital system. Experiments on the vibration control are Performed with changing the outer layer fiber orientation of intelligent composite plates.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6C
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• pp.624-633
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• 2003

We propose a novel method of selecting key VOPs from MPEG-4 compressed domain without fully decoding the compressed data. Approximated shapes of VOPs are obtained from the shape coding mode and then VOPs are clustered by shape similarity to generate key VOPs. The proposed method reduces the computation time of shape approximation, compared with Erol's method. Nevertheless, the resulting VOPs have a good summarizing capability of a video sequence. NMHD (normalized mean Hausdorff distance) values are 2-means clustered to generate key VOPs. In the video search, the MHD of a query VOP from key VOPs are computed and the VOP with the lowest distance is returned. Tests on standard MPEG-4 test sequences show that the computational complexity is very low. Recursive clustering proved to be very effective for generating suitable key VOPs.

• English Language & Literature Teaching
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• v.11 no.2
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• pp.67-89
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• 2005

Writing is a difficult skill for many people, both for children and adult alike and generally most people find it difficult to write down their thoughts effectively. Numerous studies have revealed that teachers find it frustrating to teach writing and many failed to help ESL students develop their writing ability. The theoretical emphasis on process oriented writing instruction has, in general brought about positive changes in the way writing is taught and has become widely accepted in the teaching of English as a second or foreign language (ESL/EFL). Although the interpretation and implementation of the process approach varies considerably from instructor to instructor, nevertheless, the emphasis on process writing has brought about significant and beneficial changes in teachers' orientations to writing. Despite the theoretical recognition of writing as a recursive process, many ESL/EFL classrooms continue to teach writing as a linear sequence of planning, pre-writing, writing, revising and editing and has not enhanced ESL/EFL students writing ability to the desired level. There appears to be a missing link in helping students to crystallize their thoughts before writing. Studies have shown that incorporating visual thinking tools into the process approach of ESL writing can enhance students' ability to write. This paper reports the findings of an exploratory study on the effects of using visual thinking tools in enhancing ESL students writing.

• The KIPS Transactions:PartD
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• v.15D no.2
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• pp.155-162
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• 2008

Biological sequences such as DNA sequences and amino acid sequences typically contain a large number of items. They have contiguous sequences that ordinarily consist of hundreds of frequent items. In biological sequences analysis(BSA), a frequent contiguous sequence search is one of the most important operations. Many studies have been done for mining sequential patterns efficiently. Most of the existing methods for mining sequential patterns are based on the Apriori algorithm. In particular, the prefixSpan algorithm is one of the most efficient sequential pattern mining schemes based on the Apriori algorithm. However, since the algorithm expands the sequential patterns from frequent patterns with length-1, it is not suitable for biological dataset with long frequent contiguous sequences. In recent years, the MacosVSpan algorithm was proposed based on the idea of the prefixSpan algorithm to significantly reduce its recursive process. However, the algorithm is still inefficient for mining frequent contiguous sequences from long biological data sequences. In this paper, we propose an efficient method to mine maximal frequent contiguous sequences in large biological data sequences by constructing the spanning tree with the fixed length. To verify the superiority of the proposed method, we perform experiments in various environments. As the result, the experiments show that the proposed method is much more efficient than MacosVSpan in terms of retrieval performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.7 s.98
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• pp.709-719
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• 2005

The forward link of the 3 G CDMA system may become limited under the increasing of the number of users. The conventional channelization code, Walsh code, has not enough sizes for much possible non, therefore, the quasi orthogonal function(QOF), which process optimal cross-correlation with Walsh code, is considered. In this paper, we investigate quasi orthogonal function on Jacket matrices, which can lead lower correlations values and better performance in 3 G CDMA system. Moreover, to simple the detector and improve the BER performance, a novel detection for QOF CDMA system is proposed. Finally, the simple recursive generation of the bent sequences for QOF mask function is discussed.

• KSBB Journal
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• v.22 no.4
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• pp.179-184
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• 2007

This study introduces the characteristics and some applications of repetitive polypeptides, especially to the biomaterial, tissue engineering scaffolds, drug delivery system, and DNA separation systems. Since some fibrous proteins, which consist of repeating peptide monomers, have been reported that their physical properties are changed dramatically by means of temperature alteration or pH shifting. For that reason, fibrous protein-mimetic polypeptides, which are produced by the recombinant technology, can be applied to the diverse biological fields. Repetitive polypeptides can also be used in the bioseparation area such as DNA sequencing, because they make DNA separation possible in free-solution electrophoresis by conjugating DNA fragments to them. Moreover, artificial synthesis of repetitive polypeptides helps to demonstrate the correlations between mechanical properties and structures of natural protein polymer, which have been proven that repetitive domains are affected by the sequence of the repeating domains and the number of repeating subunits. Repetitive polypeptides can be biologically synthesized using some special cloning methods, which are represented here. Recursive directional ligation (RDL) and controlled cloning method (CCM) have been proposed as excellent cloning methods in that we can control the number of repetition in the multimerization of polypeptides and the components of repetitive polypeptides by either method.

• The Transactions of the Korea Information Processing Society
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• v.2 no.5
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• pp.677-690
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• 1995

In this paper, we propose the high efficiency data compression capable of error control using block-sorting, move to front(MTF) and arithmetic code with variable length in to fixed out. First, the substring with is parsed into length N is shifted one by one symbol. The cyclic shifted rows are sorted in lexicographical order. Second, the MTF technique is applied to get the reference of locality in the sorted substring. Then the preprocessed sequence is coded using VF(variable to fixed) arithmetic code which can be limited the error propagation in one codeword. The key point is how to split the fixed length codeword in proportion to symbol probabilities in VF arithmetic code. We develop the new VF arithmetic coding that split completely the codeword set for arbitrary source alphabet. In addition to, an extended representation for symbol probability is designed by using recursive Gray conversion. The performance of proposed method is compared with other well-known source coding methods with respect to entropy, compression ratio and coding times.