• The Transactions of the Korea Information Processing Society
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• v.3 no.5
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• pp.1294-1306
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• 1996

To achieve high compression ratio for Hangul texts, in this paper two text compression algorithms which use the structural feature of Hangul, the frequency of postpositional words, are proposed. The performances of these proposed algorithms are also compared with previous text compression algorithms. The proposed compression algorithms named HLZ77 and HLZW come out from the modification of previous algorithms LZ77 and :ZW, respectively. The major distinction of the proposed ones is that the proposed algorithms use the fixed dictionary of selected postpositional words that appear most frequently in Hangul texts. The performances of HLZ77 and HLZW also are compared with those of LZ77 and LZW, respectively, with respect to the compression ratio. According to the result of performance study, the proposed algorithms are better than the previous algorithms for descriptive Hangul text snce the structural feature of Hangul is helpful to achievement of high compression ratio.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.4
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• pp.726-736
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• 1997

The textual image compression by pattern matching is a coding scheme that exploits the correlations between patterns. When we compress the Hangul (Korean character) text by patern matching, the collerations between patterns may decrease due to randoem contacts between phonemes. Therefore in this paper we separate connected phonemes to exploit effectively the corrlation between patterns by inducting the amtch. In the process of sequation, we decide whether the patterns have vowel component or not, and then vowels connected with consonant ae separated. When we compare the proposed algorithm with the existing algorith, the compression ratio is increased by 1.3%-3.0% than PMS[5] in lossy mode, by 3.4%-9.1% in lossless mode than that of SPM[7] which is submitted to standard committe for second generation binary compression algorithm.

• The Journal of the Acoustical Society of Korea
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• v.14 no.2E
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• pp.50-56
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• 1995

This paper describes an efficient coding method for Korean characters using a three-state transition graph. To our knowledge, this is the first achievement of its kind. This new method, called the Paralle Hangul Dynamic Coding Method(PHDCM), compresses about 3.5 bits per a Korean character, which is more than 1 bit shorter than the conventional codes introduced thus far to achieve extensive code compression. When we ran the method on a MasPar machine, which is on SIMD SM (EFEW-PRAM)., it achieved a 49.314-fold speedup with 64 processors having 10 million Korean characters.

• Journal of Broadcast Engineering
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• v.6 no.1
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• pp.98-107
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• 2001

In this paper we derive an optimal Huffman code set with escape coding that miximizes coding efficiency for the Hangul text data. The Hangul code can be represented in the standard Wansung or Unicode format, and we can generate a set of Huffamn codes for both. The current Korean DT standard has not defined a Hangul compression algorithm which may be confronted with a serious data rate for the digital data broadcasting system Generation of the optimal Huffman code set is to solve the data transmission problem. A relevant PSIP structure for the DTB standard is also proposed As a result characters which have the probability of less than 0.0043 are escape coded, showing the optimum compression efficiency of 46%.

• Journal of KIISE:Software and Applications
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• v.33 no.6
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• pp.580-587
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• 2006

As PDA, IMT-2000, and e-Book are developed and popular in these days, the number of users who use these products has been increasing. However, available memory size of these machines is still smaller than that of desktop PCs. In these products, TrueType fonts have been increased in demand because the number of users who want to use good quality fonts has increased, and TrueType fonts are of great use in Windows CE products. However, TrueType fonts take a large portion of available device memory, considering the small memory sizes of mobile devices. Therefore, it is required to reduce the size of TrueType fonts. In this paper, two-phase compression techniques are presented for the purpose of reducing the sire of hangul bitmap data embedded in TrueType fonts. In the first step, each character in bitmap is divided into initial consonant, medial vowel, and final consonant, respectively, then the character is recomposed into the composite bitmap. In the second phase, if any two consonants or vowels are determined to be the same, one of them is removed. The TrueType embedded bitmaps in Hangeul Wanseong (pre-composed) and Hangul Johab (pre-combined) are used in compression. By using our compression techniques, the compression rates of embedded bitmap data for TrueType fonts can be reduced around 35% in Wanseong font, and 7% in Johab font. Consequently, the compression rate of total TrueType Wanseong font is about 9.26%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.6B
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• pp.1050-1059
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• 2000

In this paper, we propose a method to improve JBIG2 compression ratio which can be applied to Hangul text. Hangul character is composed of a few symbols which is called JASO, which needs inevitable increase of position information to be transmitted. To reduce this disadvantage, we have proposed an algorithm that generate aggregated symbol in combination of JASO symbols. Proposed algorithm shows better performance in Huffman coding than in arithmetic coding. In lossless coding, proposed algorithm showed 4.5∼16.7(%) improvement for Huffman coding and 2.9∼10.4(%) improvement for arithmetic coding. In lossy coding, proposed algorithm showed 3.7∼17.0(%) improvement for Huffman coding and 2.1∼10.5(%) improvement for arithmetic coding.

• Annual Conference on Human and Language Technology
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• 1989.10a
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• pp.54-57
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• 1989

본 논문에서는 정보원의 집합이 여러개의 부집합으로 나누어지며 정보 발생 방법은 이들 부집합을 순서적으로 선택한 후 그 부집합에서 확률에 따라 원소를 발생시키는 성질을 갖는 정보원을 인코딩할 때 데이타를 압축시킬 수 있는 엔트로피 감소 모델을 제시하였다. 방법은 정보를 전송하는 과정에서 정보원이 갖고있는 성질에 관한 정보를 제외시킴으로서 평균 정보량 즉 엔트로피를 줄이는 것이다. 이와 같은 원리로 인코딩을 하면 데이타를 압축시킬수 있다.

• Annual Conference on Human and Language Technology
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• 1989.10a
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• pp.168-173
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• 1989

데이터의 압축은 화일의 저장공간과 전송시간을 줄이는 중요한 이점을 제공한다. 국내에는 많은 경우 데이터 화일에 2 바이트로 구성된 표준한글부호를 포함하고 있다. 본 논문에서는 2 바이트로 부호화 된 한글을 포함한 데이터 화일을 허프만 부호화 방식에 의해 압축 할때 한글을 한 바이트 단위로 인식하여 압축하는 경우와 두 바이트 단위로 인식하여 압축하는 경우의 여러가지 압축 특성을 비교하였다. 아울러 사전에 조사된 한글의 찾기 순서에 따라 고정된 압축 부호를 사용하는 경우와 앞에서 제시된 방법들을 비교하였다. 비교 결과 두 바이트 단위로 인식하여 압축하는 방법이 더 좋은 압축율을 보이었다.

• Annual Conference on Human and Language Technology
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• 1994.11a
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• pp.231-234
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• 1994

개인용 컴퓨터의 확산과 함께 사용자 인터페이스도 많은 발전을 하여 비데오 디스플레이의 경우 다양한 서체의 글자에 대한 지원이 필요하게 되었다. 한편 비데오 디스플레이의 경우 사용자의 입력에 대하여 빠른 응답으로써 표현되어야 하므로 복잡한 계산 과정을 갖지 않는 폰트를 이용하여야 한다. 여러 가지 종류의 폰트중에서 이에 적합한 폰트는 비트 맵 폰트이나, 비트 맵 폰트는 그 특성상 모든 종류의 서체에 대하여 각각의 데이타를 따로 가지고 있어야 하므로 저장 매체의 용량이 많이 필요하다. 그러므로 이에 대하여 비트 맵 폰트를 압축하여 저장한 다음 사용시에 하드웨어에 의하여 빠르게 복원함으로써 사용자의 입력에 대하여 빠른 응답으로 대처하는 방법에 대한 연구가 이루어지고 있다. 본 논문에서는 간단한 하드웨어를 이용하여 압축 이전에 폰트를 전처리함으로써 기존의 압축을 개선하기 위한 전처리 방법을 제안한다.

• Journal of applied mathematics & informatics
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• v.5 no.1
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• pp.191-200
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• 1998

There are two types of composition systems for the Korean alphabet: a combined system and a composite system. This paper decribes an efficient coding method for both of these two types. Using this coding method with the combined system yields about 10.5% code-length savings per a Korean character while it yields about 45% savings with the composite system. In other words the coding method produces a better result(i.e. 34.5% better) with the composite system than with the combined system. The simulation has been performed on a MasPar machine having 64 processors. The results show that the combined system achieved a 45.851-fold speedup while the composite system achieved a 47.274-fold speedup.