• Journal of Communications and Networks
• /
• v.10 no.1
• /
• pp.44-54
• /
• 2008

In this paper, an iterative multiple symbol differential detection for turbo coded differential unitary space-time modulation using a posteriori probability (APP) demodulator is investigated. Two approaches of different complexity based on linear prediction are presented to utilize the temporal correlation of fading for the APP demodulator. The first approach intends to take account of all possible previous symbols for linear prediction, thus requiring an increase of the number of trellis states of the APP demodulator. In contrast, the second approach applies Viterbi algorithm to assist the APP demodulator in estimating the previous symbols, hence allowing much reduced decoding complexity. These two approaches are found to provide a trade-off between performance and complexity. It is shown through simulation that both approaches can offer significant BER performance improvement over the conventional differential detection under both correlated slow and fast Rayleigh flat-fading channels. In addition, when comparing the first approach to a modified bit-interleaved turbo coded differential space-time modulation counterpart of comparable decoding complexity, the proposed decoding structure can offer performance gain over 3 dB at BER of $10^{-5}$.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.4
• /
• pp.1951-1956
• /
• 2013

Distribution-matching type algorithms based on a set of symbols generated in random order provide a limited performance under biased impulsive noise since the performance criterion for the algorithms has no variables for biased signal. For the immunity against biased impulsive noise, we propose, in this paper, a modified performance criterion and derived related blind algorithms based on augmented filter structures and the distribution-matching method using a set of random symbols. From the simulation results, the proposed algorithm based on the proposed criterion yielded superior convergence performance undisturbed by the strong biased impulsive noise.

• Journal of the Korean Society for information Management
• /
• v.14 no.2
• /
• pp.213-234
• /
• 1997

A stemming algorithm for the Korean language free-text retrieval system has been designed and implemented. The algorithm contains three major parts and it operates iteratively ; firstly, stop-words are removed with a use of a stop-word list ; secondly, a basic removing procedure proceeds with a rule table 1, which contains the suffixes, the postpositional particles, and the optionally adopted symbols specifying an each stemming action ; thirdly, an extended stemming and rewriting procedures continue with a rule table 2, which are composed of th suffixes and the optionally combined symbols representing various actions depending upon the context-sensitive rules. A test was carried out to obtain an indication of how successful the algorithm was and to identify any minor changes in the algorithm for an enhanced one. As a result of it, 21.4 % compression is achieved and an error rate is 15.9%.

• Journal of the Korea Fashion and Costume Design Association
• /
• v.18 no.4
• /
• pp.117-124
• /
• 2016

This study considered about freaky design of men's wear in Edo period, and also compared and analyzed it to modern men's wear. The purpose for this study is to contribute to the development of modern men's wear by this analysis. Edo period was a male dominated period, so culture of showing off their powers appeared in their fashion as symbols of skulls, monsters or tattoos. Kabuki culture used this kind of social background and it incited the actors roles and clothes to become more famous. 2016-17 F/W, 2017 S/S modern men's wear expressed more various freaky design, so it was able to be classed as shapes, pattern, materials and total coordination. Edo period just expressed freaky design by symbols however, freaky design in modern men's wear is showing more various expressions. This study can conclude that freaky design usually shows weird, peculiar, scary and dampish images. Also freaky design showed in the persuit of various choices including parade of power in modern men's wear.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.4 no.6
• /
• pp.989-1005
• /
• 2010

Cooperative diversity is a technique with which a virtual multiple antenna array is established among the single antenna users of the wireless network to realize space diversity. Signal space diversity (SSD) is a bandwidth-efficient diversity technique, which uses constellation rotation and interleaving techniques to achieve diversity gain. A new cooperative diversity scheme with rotated constellations (RCCD) is proposed in this paper. In this scheme, data are modulated by using a rotated constellation, and the source and the relays transmit different components of the modulated symbols. Since any one of the components contains full information of the symbols, the destination can obtain multiple signals conveying the same information from different users. In this way, space diversity is achieved. The RCCD scheme inherits the advantage of SSD - being bandwidth-efficient but without the delay problem of SSD brought by interleaving. The symbol error rate of the RCCD scheme is analyzed and simulated. The analysis and simulation results show that the RCCD scheme can achieve full diversity order of two when the inter-user channel is good enough, and, with the same bandwidth efficiency, has a better performance than amplify-and-forward and detect-and-forward methods.

• Journal of Information Management
• /
• v.19 no.1
• /
• pp.95-122
• /
• 1988

From the lack of common rule for the description of the characters and terms in bibliographic databases, it was hard to share information with other organizations and to obtain relevant bits of information through online retrieval. In this paper, the authors suggest a rule for the transcription of symbols and letters, that are found in articles. but impossible to input through CRT terminals, into the symbols and letters which is capable of input and retrieval. And, in the 'Hangul orthography' and 'Description rule of the borrowed words' which are officially announced by the Ministry of Education, more than two ways are permited for the expression of terms. In that case, to improve retrieval efficiency and to prevent 'confusion in description, they are regulated.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.7C
• /
• pp.467-474
• /
• 2011

The performance of pilot-symbol-assisted channel estimation widely used for OFDM systems is degraded due to the small number of pilot symbols used for higher transmission efficiency. In this paper, we propose a pilot symbol based channel estimation using cross-correlation to improve the estimation performance of the OFDM system with small number of pilot symbols. The proposed technique detects a data symbol using the channel estimated by the pilot symbol and estimates the channel using the estimated data symbol and the pilot symbol. It is shown by computer simulations that the proposed technique outperforms the conventional pilot symbol assisted estimation technique.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.9A
• /
• pp.749-757
• /
• 2011

In this paper, we propose a robust And-Or tree-based Luby transform encoded symbol packetization algorithm to minimize the quality degradation of video streaming service caused by packet losses over wireless network. To achieve this goal, the relationship among Luby transform encoded symbols are analyzed by using And-Or tree, and the proposed packetization algorithm is designed to minimize packet loss effects by reducing the dependency among packets conveying Luby transform encoded symbols. Finally, experimental results are provided to show the performance of the proposed algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.10 no.6
• /
• pp.855-865
• /
• 1999

This paper presents the improvement of BER performance using fading compensation method for 16 QAM-TCM to reduce the effects of multi-path fading in mobile radio environments. We propose the multi-pilot symbol aided fading compensation technique using Gausian interpolation method for inter-symbol interference or fading distortion occured in frequency selective fading channel. The proposed system is combined coding and modulation scheme for improving the reliability of a digital transmission system without increasing the transmitted power or the required bandwidth. In the fading compensation, the pilot symbols from a known sequence is multiplexed into the data symbols at regular intervals to from a frames for transmission. And we use a modified bit reversal block interleaver to randomize burst errors. The results show that significant improvements in the bit-error rate performances can be achieved by the proposed techniques.

• The Research Journal of the Costume Culture
• /
• v.16 no.3
• /
• pp.409-424
• /
• 2008

This study intends to analyze T-shirt designs, particularly in connection with pop art. 444 pieces of T-shirts which conveyed the pop art spirits of well-known designers were selected for five years from 2001 to 2005, through fashion magazines(Collection: Dong-ah TV, Collezioni: Italy). The findings are as follows. As for formative characteristics of pop art in T-shirts, previous studies were analyzed to set classifications criteria such as popularization of images, eroticism, lettering and graffiti, assemblage. The design factor of the image popularization includes everyday images, cartoon, celebrities, and caricature. Everyday images ranked first followed by cartoon, caricature and celebrities. The design factor of eroticism ranges from the see-through look, partial exposure of human body, symbolization of underwear, and to printing of sexy images. The see-through look was ranked first, followed by partial exposure of human body, symbolization of underwear, and printing of sexy images. The design factor of lettering and graffiti encompasses letters, numbers, symbols and logos. Adoption of letters, numbers or symbols was ranked first, followed by brand logos and graffiti. The design factor of Assemblage is closely related to a three-dimensional effect. Varied expressions are possible: combination of two different textiles and fusion of textile and non-textile. Combination of two different textiles are higher than fusion of textile and non-textile.