• 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.690-696
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• 2005

It is very important to reduce the PAPR(Peak to Average Power Ratio) in the OFDM(Orthogonal Frequency Division Multiplexing) communication system. The proposed method in this paper is an effective PAPR reduction method using the Golay complementary codes without my side information. There are some PAPR reduction methods with the complementary code pairs or sequences. They are usually a type of the forward ewer correction codes so that they produce more redundancies and lower down the code rate. Because of this, the information rate may be cut down or more bandwidth must be required. In this paper, we propose a PAPR reduction method that uses the multi-phase complementary code f3r converting the 4-QAM into 16-QAM constellation. It does not change the code rate and does not require the side information.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.10C
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• pp.605-613
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• 2011

In most digital communication systems over the noisy channel, some form of forward error correction scheme is employed for reliable communications. If one wants to recover the transmitted message without any knowledge of the error correcting codes employed, it is of utmost importance to figure out and reconstruct the error correcting codes. In this paper, we propose two algorithms of reconstructing linear cyclic codes from the corrupted received bit sequence, one for general linear binary cyclic codes and the other for Reed-Solomon codes. For two algorithms, we ran computer simulations and the performances are shown to be superior to those with the conventional LWM method.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10b
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• pp.907-910
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• 2000

만화 영상은 대체적으로 단순하면서도 일정한 기울기(Gradation)를 가지는 영역이 많이 존재한다. 본 논문에서는 이러한 만화 영상의 특징을 고려해서 상보 쿼드트리를 이용한 효율적인 압축방법을 제안하고자 한다. 제안한 방법에서 상위마디의 색상은 하위 마디 중에서 가장 많은 부분을 차지하는 색상이 되며 각각의 마디는 형태 부호와 색상 부호 또는 형태 부호와 기울기 값으로 나타내어진다. 기울기를 가지는 영역이 많이 존재하는 만화 영상에서 제안한 방법은 기존의 다른 압축 방법보다 비트수를 줄일 수 있고, 무손실 점진적 전송도 가능하다.

• Journal of Broadcast Engineering
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• v.19 no.4
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• pp.491-501
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• 2014

Recently, the need for disaster-preventing broadcast has increased gradually to cope with natural disaster like earthquake and tsunami causing enormous losses of both life and property. In disaster-preventing broadcast system, the wake-up signal is used to alert user terminal and switch the current state of channel to the emergency channel, which is for the fast and efficient delivery of emergency information. In this paper, we propose the detection method of wake-up signal for disaster-preventing broadcast systems. The wake-up signals for disaster-preventing broadcast should have a good auto-correlation property in low power and narrow-band conditions that does not affect the existing digital television (DTV) system. The suitability of the m-sequence and complementary code (CC) is analyzed for wake-up signals according to signal to noise ratio. A wake-up signal is proposed by combining the direct sequence spread spectrum (DSSS) technique and pseudo noise (PN) sequences such as Barker and Walsh-Hadamard codes. By using the proposed method, a higher detecting performance can be achieved by the spreading gain compared to the single long m-sequence and the Golay code.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.9C
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• pp.817-824
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• 2006

The crest factor properties of 16-QAM modulated one- and two-code assisted multi-carrier code-division multiple-access (MC-CDMA) signals employing complementary pair as spreading sequences are characterized. It is shown that a set of relationship between the two 16-QAM symbols entirely characterize the power envelope waveforms of the signals. There exists 60 different sets of relationship, which results in 16 different crest factors as a result of various equivalent transforms on the corresponding message symbols. It is also shown that the individual crest factor corresponding to each message combination is always bounded by 3dB.

• The Transactions of the Korea Information Processing Society
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• v.4 no.1
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• pp.209-214
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• 1997

In this paper, we propose a new preorder tree method for binary images, named the Compact Complementary Quadtree (CCQ). In the proposed method we use type codes for representing nodes in the quadtree instead of using the symbols G, B, and W. From the experimental results, we have confirmed that the CCQ has a higher compression ratio than of the DF-expression. CCQ can be effectively applied to progressive transmission of binary images such as line drawings, geographical maps, and halftones.