• The Journal of the Acoustical Society of Korea
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• v.16 no.1E
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• pp.35-40
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• 1997

The LZW algorithm has some redundancies for voice traffic. Thus, the V-LZW(Voice LZW) algorithm that decreases the redundancies of the LZW algorithm is suggested for efficent compression of voice. The V-LZW algorithm uses the differential method that reduces the codeword size as well as the length of repeated string. According to the simulation results, it could be seen teat the performance of V-LZW algorithm is better by 35% to 44% in voice compression ratio than that of the conventional modified LZW algorithm. Compared with conventional 32 kbps ADPCM coding with 26 dB SNR, V-LZW has 21 kbps transmission rate, no additional quantization error and simple hardware complexity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.8
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• pp.698-707
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• 1990

As proved in many studies, LZW algorithm, one of the widely used compression schemes, itself contains some types of redundancy, In this paper, VV-LZW coompression algorithm is presented which encodes variable length source string into variable size codewords and reduces such redundancies that the original LZW scheme has. Experiment shows that this scheme especially has good initial compression efficiency and produces more complex output strings than the original LZW. This scheme is very useful to the data compression with small size, and the applications such as crytography.

• The Journal of the Korea Contents Association
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• v.10 no.12
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• pp.70-76
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• 2010

This paper Extended ELZW(EBCDIC Lempel Ziv Welch) algorithm uses 2 byte prefix field for pointer of a table and 1 byte suffix field for repeat counter. where, a prefix field uses a pointer(index) of compression table and a suffix field uses a counter of overlapping or recursion text data in compression table. To increase compression ratio, after construction of compression table, table data are properly packed as different bit string in accordance with a alphabet, Hangeul, and pointer respectively. Therefore, proposed ELZW algorithm is superior to 1byte LZW algorithm as 5.22 percent and superior to 2byte LZW algorithm as 8.96 percent.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.688-690
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• 2002

LZW 알고리즘은 사전방식의 압축 알고리즘인 LZ78의 변형된 형태로써 높은 압축률을 제공하기 때문에 많은 압축 방법에서 사용되고 있다. LZW에서 사전을 이용하는 방식은 LZ78과는 달리 미리 문서에 나오는 문자들을(즉, ASCII 코드) 미리 저장해 놓고 압축을 한다. 본 논문은 Hyper-Text에서는 같은 단어가 자주 반복되는 것에 착안하여 그러한 한 단어를 코드형태로 미리 저장해 놓고 LZW알고리즘을 적용하였다. 본 논문에서 제시하는 방법의 성능을 테스트하기 위해 기존의 V.42bis에 이러한 확장된 초기사전을 적용한 후 기존의 V.42bis 및 UNIX의 compress에 비교하였다. 실험결과를 통해 기존의 V.42bis와 compress에 비해 각각 17.9%와 17.5%의 향상된 성능을 확인할 수 있다.

• The KIPS Transactions:PartA
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• v.9A no.3
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• pp.311-316
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• 2002

LZW is a popular variant of LZ78 to compress text documents. LZW yields a high compression rate and is widely used by many commercial programs. Its core idea is to assign most probably used character group an entry in a dictionary. If a group of character which is already positioned in a dictionary appears in the streaming data, then an index of a dictionary is replaced in the position of character group. In this paper, we propose a new efficient method to find least used entries in a dictionary using counter. We also achieve higher compression rate by preassigning widely used tags in hyper-text documents. Experimental results show that the proposed method is more effective than V.42bis and Unix compression method. It gives 3∼8％ better in the standard Calgary Corpus and 23∼24％ better in HTML documents.

• Annual Conference of KIPS
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• 2015.04a
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• pp.652-654
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• 2015

최근 ICT융합 기술의 비약적인 발전에 따라 소형 휴대가 가능한 다양한 종류의 생체신호 측정센서의 출현으로 유헬스케어 관련 기술이 비약적으로 발전하게 되면서, 실시간으로 발생하는 생체데이터에 대한 효율적인 처리가 중요하게 되었다. 따라서 본 논문에서는 M2M기반에서 발생되는 생체데이터의 효율적인 전송을 위해 LZW(Lempel-Ziv-Welch) 압축 알고리즘과, BitVector압축 알고리즘을 결합한 LZW-BitVector 압축 알고리즘을 제안한다.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.446-449
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• 2002

This paper represents a improved data compression algorithm of mixed text file by 2 byte completion Hangout and 1 byte alphabet from. Original LZW algorithm efficiently compress a alphabet text file but inefficiently compress a 2 byte completion Hangout text file. To solve this problem, data compression algorithm using 2 byte prefix field and 2 byte suffix field for compression table have developed. But it have a another problem that is compression ratio of alphabet text file decreased. In this paper, we proposes improved LZW algorithm, that is, compression table in the Extended LZW(ELZW) algorithm uses 2 byte prefix field for pointer of a table and 1 byte suffix field for repeat counter. where, a prefix field uses a pointer(index) of compression table and a suffix field uses a counter of overlapping or recursion text data in compression table. To increase compression ratio, after construction of compression table, table data are properly packed as different bit string in accordance with a alphabet, Hangout, and pointer respectively. Therefore, proposed ELZW algorithm is superior to 1 byte LZW algorithm as 7.0125 percent and superior to 2 byte LZW algorithm as 11.725 percent. This paper represents a improved data Compression algorithm of mixed text file by 2 byte completion Hangout and 1 byte alphabet form. This document is an example of what your camera-ready manuscript to ITC-CSCC 2002 should look like. Authors are asked to conform to the directions reported in this document.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.1
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• pp.10-23
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• 1994

To transmit information efficiently and securely in On-line transmission, data compression, secrecy and authentication are required. In this paper, we propose LZWH4 which creates two compression strings with applying Hnageul to LZW. design HDES1 by extending S-box (S1-S16) which satsfies SAC and correlation coefficient as a partial countermeasure of Differential Cryptanalysis and implement LZWHDES1 which concatenates efficiently these for digital signature in On-line transmission. Also HDES1 is more in U.D.(Unicity Distance) than DES and HDES. We show that the proposed LZWHDES1 reduces processing times than LZWHDES which LZW is directly concatnated to DES and LZWHDES which LZWH1 is directly concatenated to HDES. LZWHDES1 can be used to digital signature system as conventional key cryptosystem.

• Journal of Digital Convergence
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• v.12 no.4
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• pp.251-257
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• 2014

In u-Healthcare environment, large amounts of important vital information is processed through M2M(Machine to Machine). M2M is configured by wireless networks and has several problems for limited bandwidth and low reliability. Therefore, in this paper is proposed a method called uHLZW(u-Healthcare LZW) to improve channel efficiency to solve such problem. uHLZW algorithm has high compression ratio for vital data. The results showed that the average compression ratio of uHLZW got from 1.6 times to 4.0 times better than existing methods(Huffman and LZW compression).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.5A
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• pp.545-553
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• 2004

Expansion of network environment and multimedia demand universality of application service as HDTV, etc. During these processes, it is essential to process multimedia in real time in the wireless communication system based on mobile phone network and in the wire communication system due to fiber cable and xDSL. So, in this Paper the optimal memory allocation algorithm combines the merit of huffman encoding which is superior in simultaneous decoding ability and lempel-ziv that is distinguished in execution of compress is proposed to improve the channel transmission rate and processing speed in the compressing procedure and is verified in the entropy encoder of HDTV. Because the entropy encoder system using proposed optimal memory allocation algorithm has memory saturation prevention we confirms that the compressing ratio for moving pictures is superior than Huffman encoding and LZW.