• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1A
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• pp.44-50
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• 2007

In typical MC-CDMA systems, different frequency-domain scrambling codes are randomly chosen from a given code set and then assigned to different subscriber stations using the same subcarrier set. When orthogonal codes are employed for the frequency-domain scrambling, the choice of the scrambling code does not affect the detection performance if the timing and frequency synchronizations are perfect and the channel characteristic is flat. However, in practical cases, inter-code interference often appears due to the broken code orthogonality. In this paper, the optimal order of allocating the orthogonal frequency-domain scrambling codes to new subscriber stations is derived under non-negligible timing offsets in MC-CDMA system.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.9
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• pp.1019-1026
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• 2015

This paper studied the source coding rule of the characters to minimize the HDB-3 scrambling for UTF-8 code. An existing source coding rule of the characters to minimize the HDB-3 scrambling in the line coder is for the source codes which are directly entered into the line coder without any transformation. Therefore the existing source coding rule can't apply the UTF-8 code which is directly came into an input of line coder. The reason is that the scrambling code in the source codes are not same as UTF-8 codes. So, if they want to analysis the scrambling occurrence situation in UTF-8 codes and make an unscrambling UTF-8 code, they should make a UTF-8 code table for the source codes, find out the scrambling occurrence codes and then encode the unscrambling source code. The source coding rule for UTF-8 code showing this paper can omit such a complicated procedure to encode an unscrambling source code.

• KIPS Transactions on Computer and Communication Systems
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• v.10 no.9
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• pp.235-242
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• 2021

Most data scrambling schemes generate pure random codes. Unlike these schemes, we propose a variable density scrambling scheme (VDSC) that differentiates densities of generated codes. First, we describe conditions and methods to translate plain codes to cipher codes with different densities. Then we apply the VDSC to flash memory such that preferred cell states occur more than others. To restrain error rate, specifically, the VDSC controls code densities so as to increase the ratio of center state among all possible cell states in flash memory. Scrambling experiments of data in Windows and Linux systems show that the VDSC increases the ratio of cells having near-center states in flash memory.

• Journal of Advanced Navigation Technology
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• v.16 no.5
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• pp.831-838
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• 2012

In the transmission system, the transmission efficiency can be increased by applying the proper character coding method. This paper is to show the character coding rule in computer and information equipment etc to improve the transmission efficiency in datacommunications. The character coding rule showing in this paper was suggested by considering the two view points. First one is FLAG bits in HDLC and PPP protocol on datalink layer in OSI 7 layer. Second one is one of the scrambling method, HDB-3, on physical layer in OSI 7 layer. The former is to prevent the sequence of over 5bits of "1" in the character codes. The latter is to prevent the sequence of over 4bits of "0" in the character codes.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.7
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• pp.831-836
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• 2015

This paper studied scrambling occurrence in the line coder for UTF-8 hangul syllable code based on unicode. The paper suggested that scrambling is occurred when consecutive four "0" bit is entered into the line coder from the source codes. Currently, ITU-T is applying HDB-3 scrambling method in AMI line coder, According to the study result, scrambling is occurred about 39% in UTF-8 code on Unicoe Hangul syllable.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.1
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• pp.162-177
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• 2012

In this paper we present a novel method of applying image scrambling technology which belongs to the information hiding field in the error control coding to introduce confidentiality in wireless machine to machine communication. The interleaver in serial concatenated convolutional codes, which is the key module in overcoming burst errors, is deliberately designed with the scrambling function to provide a low error rate for those authorized transceivers. By contrast, the unauthorized transceivers without keys would get so high an error rate that decoding bits could bring little value, thus realizing both the confidentiality and reliability in wireless machine to machine communication.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.8
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• pp.1649-1655
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• 2005

For systems with coexisting cellular and hot-spot cells in broadband orhogonal frequency and code division multiplexing (OFCDM) systems, a suitable cell search algorithm is proposed fur the common pilot channel (CPICH) in the forward link using separated I/Q channel cell specific codes(CSSC), in which the cellular cell specific scrambling code (CCSSC) is assigned to the in-phase (Q) pilot channel of all cellular cells, and the exclusive hot-spot cell specific scrambling code (HSCSSC) group is assigned to the quadrature (Q) pilot channel of all hot-spot cells. Therefore, the proposed algorithm enables a mobile station (MS) to search quickly for the most desirable hot-spot cell due to reducing the effect of CCSSC, when a MS wants to use a mobile internet. The computer simulation results show that the proposed cell search algorithm can achieve faster cell search time performance, compared to conventional cell search methods.

• Journal of Advanced Navigation Technology
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• v.19 no.2
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• pp.153-160
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• 2015

This paper has studied about the scrambling occurrence frequency in UTF-8 coding system for Unicode Hangul Jamo codes. The scrambling methode applied in the study is HDB-3 in AMI line coding that is international transmission standard. In the study, the source coding rule was applied to analysis the scrambling occurrence. The quantity of the scrambling occurrence was calculated by the number of times and frequency rate of the scrambling occurrence in Hangul Jamo and Compatibity Hangul Jamo. In the case of Hangul Jamo, the number of times and frequency rate in Unicode and UTF-8 were 24times, 52% and 148times, 228% respectively. In the case of Compatibility Hangul Jamo, that were 10times, 14% and 83times, 131% respectively. As a result, when Hangul Jamo and Compatibility Hangul Jamo in UNICODE were transformed to UTF-8, the scrambling frequency rates were increased 340% and 851% respectively.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.1
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• pp.39-46
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• 2015

The paper studied possibility of improvement of efficient of data processing in the line coder when Hangul syllables in Unicode system is used for the source code. The scrambling in the line coder is to solve the problem happened due to the source code. The study is based on the HDB-3 scrambling method in ITU-T standards that is applied to AMI line coder. The referred data of Hangul syllables and its use frequency which are required to analysis was used the data extracted from the source data of the National Korean Language Institute. According to the analysis, the average 24% scrambling was generated in source code of Hangul syllables in Unicode system. When the referred Hangul syllables was applied to Unicode system, the average 27% scrambling was producted. Total 8,924ea Hangul syllables in 11,172ea Hangul syllables in Unicode system were not scrambled. Therefore the referred Hangul syllables 1,540ea were accepted in the unscrambled code areas. As a result, the existing Unicode Hangul syllable codes can't prevent the scrambling, but it is possible to completely remove the 27% scrambling with new source coding system. And then, it can be improved the data processing efficient upto minimum 27% in line coder by software in presentation layer instead of physical layer.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.4
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• pp.499-504
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• 2011

This paper propose the rule of coding for the characters and symbol, etc which are used in computer, information devices, etc. When they use the rule of coding, they may improve the efficiency of transmission in data communications by reducing the number of scrambling during the line coding in the coder in the transmitter. The paper considered the codes of one byte of 3bits column ${\times}$ 4bits rows. ASCII code is one of the representative code for the codes of one byte of 3bits column ${\times}$ 4bits rows. Therefore, this paper applied ASCII code to study the coding rule of the characters and symbols, etc.