• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.2
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• pp.22-28
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• 2007

High PAPR (peak-to-average power ratio) is a major drawback of OFDM (orthogonal frequency division multiplexing) signals. In this paper, a modified SLM (selective mapping) technique that uses erasure decoding of RS (Reed-Solomon) codes is presented. At the transmitter a set of phase sequences are multiplied such that some portions of check symbols in RS-coded OFDM data blocks are phase-rotated. At the receiver, RS decoding is performed with the phase-rotated check symbols being treated as erasures. Hence, there is no need to send side information about the phase sequence selected to transmit for the lowest PAPR. In addition, the estimation process for the selected phase sequence is no longer needed at the receiver, leading to improvement in terms of complexity and performance. To evaluate the performance of this technique, the CCDF (complementary cumulative distribution function) of PAPR, the BER (bit error rate) and the decoding failure probability are compared with those of the previous SLM techniques.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.4
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• pp.17-25
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• 2013

In this paper, a coding algorithm is proposed for multi-user multi-input multi-output (MU-MIMO) systems to improve the reception performance in fading conditions without reducing the bandwidth efficiency. The space division multiple access (SDMA) scheme that is one of the commonly used for MU-MIMO systems is vulnerable to the fading. The space time block code (STBC) scheme that is used to overcome the fading has a disadvantage of reduced throughput. The proposed MU-MIMO system first encodes transmitted symbols by linear dispersion code (LDC) which is less vulnerable to the fading and increases the throughput in proportional to the number of transmit antennas. Then, the LDC coded symbols are pre-coded by the result of singular value decomposition (SVD) of the estimated channel gain. We evaluate the performance of the proposed scheme compared with the conventional algorithms by computer simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1645-1652
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• 2016

FTN(Faster-Than-Nyquist) signaling is a method of transmitting symbols at rates faster than the Nyquist rate in the same bandwidth by overlapping transmission pulses. The transmission power of the FTN signal is greater than that of the Nyquist signal, because the number of symbols in the FTN signal is larger than that in the Nyquist signal for the same time interval. Hence, to evaluate the performance of an FTN-based transmission system properly, the performance evaluation criterion should be carefully set, and conversion formulas among the criteria which are used in Nyquist-based system should also be applied attentively. In this paper, the performance evaluation criteria of the FTN-based transmission system is analyzed and a valid way to set the criteria is proposed.

• Archives of design research
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• v.18 no.4 s.62
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• pp.5-14
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• 2005

Local self-governing bodies have created community identity to activate local communities. community identity is one of the very effective ways to establish a different image from other self-governing bodies and to raise locals' love of hometown and sense of belonging. In addition to community identity., there are several things to form identity such as symbols (like flowers, birds, and animals) of local self-governing bodies or characters visualizing figures, tradition, and specialties of the region. Recently local governments have introduced various programs such as brand planning like city brand, and local events. This study analyses the basic elements, like symbol mark, logotype, and color, among visual elements of the current local self-governing bodies community identity. and conducts a comparative analysis of the visual elements of symbols and characters. The results show that those community identities and other design elements lack differentiation and consistency among visual elements. To create differentiated image of local self-governing bodies, it needs to develop unique and various themes of the region and to generate synergy effect through consistency and interactions among various visual effects based on community identity.

• Journal of the Korean Society of Costume
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• v.61 no.1
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• pp.58-68
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• 2011

With Expo 2012 Yeosu to be held in 2012, this study intends to propose designs for fashion cultural products into which the characteristics of local cultures of Yeosu are fused. Using symbols of Expo 2012 Yeosu and cultural symbols of Yeosu City as motifs, this study will develop patterns and then, apply them to neckties, handkerchiefs, and T-shirts. Adobe Illustrator CS2 and Adobe Photoshop CS2 will be used. This study developed basic motifs so that cultural resources using camellia, Odong Island, and the Turtle Ship, which represent Yeosu City, could be well harmonized with the topic of Expo 2012 Yeosu. This paper set three basic motifs of new formative images, using graphic images that were made by omission of forms, simplification, overlap, repetition, and calligraphy of the name of Yeosu holding the event. Each set motif was expanded to three motifs again through change, conversion, and mixture of colors, and three types of repetitive applied patterns were developed through revolution, symmetry, repetition, and reversal of each motif. The modern and refined image for neckties, to which the developed motif was applied, was made by directly applying the repetitive pattern of each motif or by making $45^{\circ}$ revolution. For handkerchiefs, revolution, enlargement, reduction, and gradation were applied to the motif so the pattern could be highlighted to the maximum and finally, a colorful image was developed. For T-shirts, three designs-a half-sleeved box type, a sleeveless round neckline type, and a sleeveless V-neckline tight type-were developed, through which availability of the design was increased. Through enlargement, reduction, revolution, and repetition of each motif, this paper layout the pattern on the whole part of a T-shirt, pursuing a decorative and casual image.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.8
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• pp.1241-1252
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• 2009

This study is on the internal and external characteristics along with the phenomena of dress and ornaments expressed in them by analyzing Re-orienting Fashion (which is a system of signs and symbols) based on the theories of semiology in the search for the Korean identity by examining a Re-orienting Fashion that is being reinterpreted. Re-orienting Fashion performs the role of signs that act in the spread of Oriental culture through the globalization of traditional dress and ornaments in the Orient. It also has a meaning that converts the world of fashion to a new direction. When analyzing the system of signs and symbols in Re-orienting Fashion (based on the theories of semiology) the conclusions are that an eclectic symbol system has been formed by the combination of the pursuit of modernization in traditional dress and ornaments with post-modernism. A nature-friendly symbol system has been shaped as a natural silhouette in terms of the combination with Eastern philosophy that searches for a harmony with nature according to ecological trends. The ideal of a symbol system means the introduction of design elements in traditional dress and ornaments of the East as a rejection of Western civilization and as an alternative to the fixed pattern of the West.

• Journal of Korea Multimedia Society
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• v.10 no.10
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• pp.1284-1294
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• 2007

In this paper, a blind nonlinear channel equalization is implemented by using a Modified Fuzzy C-Means (MFCM) algorithm. The proposed MFCM searches the optimal channel output states of a nonlinear channel from the received symbols, based on the Bayesian likelihood fitness function instead of a conventional Euclidean distance measure. Next, the desired channel states of a nonlinear channel are constructed with the elements of estimated channel output states, and placed at the center of a Radial Basis Function (RBF) equalizer to reconstruct transmitted symbols. In the simulations, binary signals are generated at random with Gaussian noise. The performance of the proposed method is compared with that of a hybrid genetic algorithm (GA merged with simulated annealing (SA): GASA), and the relatively high accuracy and fast searching speed are achieved.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2007.05a
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• pp.382-388
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• 2007

In this paper, a modified Fuzzy C-Means (MFCM) algorithm is presented for nonlinear blind channel equalization. The proposed MFCM searches the optimal channel output states of a nonlinear channel from the received symbols, based on the Bayesian likelihood fitness function instead of a conventional Euclidean distance measure. Next, the desired channel states of a nonlinear channel are constructed with the elements of estimated channel output states, and placed at the center of a Radial Basis Function (RBF) equalizer to reconstruct transmitted symbols. In the simulations, binary signals are generated at random with Gaussian noise. The performance of the proposed method is compared with that of a hybrid genetic algorithm (GA merged with simulated annealing (SA): GASA), and the relatively high accuracy and fast searching speed are achieved.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.4
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• pp.823-832
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• 2011

In this paper, an efficient blind carrier frequency offset (CFO) estimation method in orthogonal frequency division multiplexing (OFDM) systems is proposed. In the proposed method, we obtain two time different received OFDM symbols by using both the cyclic prefix and oversampling technique, and a cost function is defined by using the two OFDM symbols. We show that the cost function can be approximately expressed as a cosine function. Using a property of the cosine function, a formular for estimating the CFO is derived. The estimator of the CFO requires three independent cost function values calculated at three different points of frequency offset. The proposed method is very efficient in computational complexity since no searching operation for the minimum cost value is required. The proposed method reduces 97% of the amount of FFT computation, compared with the ML method. Unlike the conventional methods such as the ML method and the MUSIC] method, the accuracy of the proposed method is independent of the searching resolution since the closed form solution exists. The computer simulation shows that the performance of the proposed method is superior to those of the MUSIC and the ML method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.9
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• pp.2009-2019
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• 2013

In this paper, we propose an automatic modulation recognition algorithm based on cyclic moment and new modified cumulant for analog and digital modulation signals. It is noteworthy that each modulated signal has different cycle frequency characteristics according to its order of cyclic moment. By means of this characteristics as classification features, various modulated signals can be efficiently classified. Also, to identify modulated signals having the same cycle frequency characteristics, we take advantage of the additional classification factors such as variations of envelope and phase as well as modified cumulant. The proposed algorithm was evaluated by considering the number of symbols, SNR, and frequency offset. In the simulation condition where the number of gathered symbols was about 819, and SNR and frequency offset were above 10dB and below 25%, respectively, the average accuracy of the proposed algorithm was more than 95%.