• 한국컴퓨터정보학회논문지
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• 제22권5호
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• pp.81-88
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• 2017

Solar-powered wireless sensor nodes can use extra energy to obtain additional data to increase the precision. However, if the amount of data sensed is increased indiscriminately, the overhead of relay nodes may increase, and their energy may be exhausted. In this paper, we introduce a sensing and compression rate selection scheme to increase the amount of data obtained while preventing energy exhaustion. In this scheme, the neighbor nodes of the sink node determine the limit of data to be transmitted according to the allocated energy and their descendant nodes, and the other nodes select a compression algorithm appropriate to the allocated energy and the limitation of data to be transmitted. A simulation result verifies that the proposed scheme gathers more data with a lower number of blackout nodes than other schemes. We also found that it adapts better to changes in node density and the amount of energy harvested.

• 음성과학
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• 제9권4호
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• pp.165-173
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• 2002

Strong compression effects in a stressed vowel due to the addition of syllables have been adopted as evidence for stress-timing. In relation to this, Yun (2002) investigated the compression effects of number of syllables on Korean vowel. The results generally revealed that Korean had neither significant nor consistent anticipatory or backwards compression effects, especially when it came to the sentence level. This led us to claim that Korean would not be a stress-timed language. But the language investigated in the study was only Korean, and further cross-linguistic research was needed to confirm the claim. In this study, Yun's (2002) sentence level data are compared with Fowler's (1981) English data. The comparison reveals that Korean seems to be similar to English in the backwards compression effect, whereas the two languages are markedly different in the anticipatory compression effect. Thus, if English is a stress-timed language and the strong anticipatory compression effect is evidence in favour of stress-timing as is claimed, the present cross-linguistic study confirms Yun's (2002) suggestion-Korean is unlikely to be stress-timed. On the other hand, compression effects are revisited: the differences in vowel compression between English and Korean are discussed from the syntactic and phonological points of view.

• 한국컴퓨터산업학회논문지
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• 제5권7호
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• pp.737-746
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• 2004

본 논문에서는 영상 데이터 압축을 위하여 2- 채널 멀티웨이브렛 변환을 적용하였다. 멀티웨이브렛 시스템은 음성 데이터 등의 비정상적인 신호의 압축에 스칼라 웨이브렛 시스템을 능가하는 우수한 성능을 나타내는 것으로 알려져 있으나 2차원 데이터인 영상 데이터의 경우에는 멀티웨이브렛 시스템 특유의 시각적 격자 오류가 발생하는 문제가 있다. 본문의 멀티웨이브렛 변환 및 압축 시스템에서는 멀티웨이브렛 효과에 의하여 발생하는 격자 오류를 제거하기 위하여 전후처리 필터링을 멀티웨이브렛 변환 및 압축 시스템에 접목하는 방법을 제시하였다. 또한, 제안한 시스템의 성능을 검증하기 위하여 컴퓨터 시뮬레이션을 수행하였으며 영상 데이터의 압축 기능 측면에서 스칼라 웨이브렛 시스템과 비교하였다. 이때, 비트 할당과 양자화를 위해서 전송율 결과는 제안한 멀티웨이브렛 변화 및 압축 시스템이 스칼라 웨이브렛 시스템 보다 영상 압축 성능 측면에서 1 ~ 2 dB 우수한 것으로 나타났다. 만약 SPIHT과 run-length 채널 부호화 기법 등의 우수한 압축 기술을 멀티웨이브렛 변환 시스템에 적용한다면 더욱 우수한 성능 개선 효과를 기대할 수 있을 것으로 사료된다.

• 항공우주산업기술동향
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• 제6권2호
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• pp.90-98
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• 2008

최근 고해상도위성의 개발 및 활용이 활발해지면서, 데이터 전송 및 처리를 위한 영상압축의 중요성이 대두되고 있다. 이에 발맞추어 CCSDS (Consultative Committee for Space Data Systems)에서는 고해상도위성의 영상압축권 고안인 CCSDS 122.0-B-1을 2005년 말에 발표했으며, 이는 향후 고해상도 위성의 영상압축에 널리 적용될 것으로 기대된다. 본 논문에서는 고해상도위성의 최근 동향을 알아보고, CCSDS 122.0-B-1 기반의 고해상도위성 영상압축 기술에 대해 설명하며, JPEG과 성능을 비교한 결과를 기술한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.228-230
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• 2002

We present a new low power scan testing and test data compression method for System-On-a-Chip (SOC). The don't cares in unspecified scan vectors are mapped to binary values for low power and encoded by adaptive encoding method for higher compression. Also, the scan-in direction of scan vectors is determined for low power. Experimental results for full-scanned versions of ISCAS 89 benchmark circuits show that the proposed method has both low power and higher compression.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.491-494
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• 1999

Introduction of digital communication network such as Integrated Services Digital Networks(ISDN) and digital storage media have rapidly developed. Due to a large amount of image data, compression is the key techniques in still image and video using digital signal processing for transmitting and storing. Digital image compression provides solutions for various image applications that represent digital image requiring a large amount of data. In this paper, the proposed DWT(Discrete Wavelet Transform) filter bank is consisted of simple architecture, but it is efficiently designed that a user obtain a wanted compression rate as only input parameter. If it is implemented by FPGA chip, the designed encoder operates in 12MHz.

• 한국산학기술학회논문지
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• 제10권1호
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• pp.110-116
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• 2009

DVR 시스템은 비디오 데이터를 저장/재생해야 하기 때문에 대용량의 비디오 데이터를 압축하는 것이 매우 중요하다. 압축 방법으로 기존의 MPEG-4 압축을 사용하는 고성능 DVR 제품군은 국내외 적으로 다수가 있으나, 성능은 대부분 입력 영상에 비해서, 열화된 영상 크기인 CIF(D1/4)크기를 압축하는 DVR이 대다수이다 본 논문에서는 DSP를 이용하여 M-JPEG과 H.264 코덱을 구현하였다 M-JPEG은 다채널 모니터링을 위한 네트워크 전송용으로 사용하였으며, H.264는 Baseline Profile을 지원하여 기존의 MPEG-4 압축에 비해 $2{\sim}4$배 압축률 상승시켰다. 그 결과 가로 720픽셀, 세로 480픽셀의 고해상도를 지원할 수 있게 되었다.

• 한국항해항만학회지
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• 제46권2호
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• pp.92-98
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• 2022

Maritime accidents result in enormous economic loss and loss of life; thus, such accidents must be prevented, and risks must be managed to prevent these occurrences Risk management must be based on statistical evidence such as variables. Because calculating when variables increase statistically can be difficult, compressing the designated variables is necessary to use the maritime accident data in Korea. Thus, in this study, variables of marine accident data are compressed using statistical methods. The date, ship type, and marine accident type included in all maritime accident data were extracted, the number of optimal variables was confirmed using the hierarchical clustering analysis method, and the data were compressed. For the compressed variables, the validity of the data use was statistically confirmed using analysis of variance, and the data of the variables identified using the variable compression method were designated. Consequently, among the monthly and yearly data, statistical significance was confirmed in yearly data, and compression was possible. The significance of the data was confirmed in six and eight types of ships and accidents, respectively, and these were compressed. These results can be directly used for prevention or prediction based on past maritime accident data. Additionally, the data range extracted from past maritime accidents and the number of applicable data will be studied in the future.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권12호
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• pp.4648-4663
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• 2020

This paper proposes the Lempel-Ziv 4(LZ4) compression accelerator optimized for scale-out servers in data centers. In order to reduce CPU loads caused by compression, we propose an accelerator solution and implement the accelerator on an Field Programmable Gate Array(FPGA) as heterogeneous computing. The LZ4 compression hardware accelerator is a fully pipelined architecture and applies 16 dictionaries to enhance the parallelism for high throughput compressor. Our hardware accelerator is based on the 20-stage pipeline and dictionary architecture, highly customized to LZ4 compression algorithm and parallel hardware implementation. Proposing dictionary architecture allows achieving high throughput by comparing input sequences in multiple dictionaries simultaneously compared to a single dictionary. The experimental results provide the high throughput with intensively optimized in the FPGA. Additionally, we compare our implementation to CPU implementation results of LZ4 to provide insights on FPGA-based data centers. The proposed accelerator achieves the compression throughput of 639MB/s with fine parallelism to be deployed into scale-out servers. This approach enables the low power Intel Atom processor to realize the Hadoop storage along with the compression accelerator.

• ETRI Journal
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• 제25권3호
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• pp.156-170
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• 2003

Gamut compression algorithms have traditionally been defined functionally and then tested with deductive methods, e.g., psychophysical experiments. Our study offers an alternative, an inductive method, in which observers judge image colors to represent the original images more accurately. We developed a computer-controlled interactive tool that modifies the color appearance of pictorial images displayed on a monitor. In experiments, observers used the tool to alter color pixels according to the region of color space to which they belonged. We created three different gamut compression algorithms based on the observer experimental data. Observer groups evaluated the performance of the newly-developed algorithms, existing gamut compression algorithms, and an image based on the average observers' results from experiments in this study. The study of gamut extension is unlike the study of gamut compression in that it mainly deals with the degree of image pleasantness as judged by observers. The results of the gamut extension experiments in this study not only make available worthwhile data but also suggest a methodology for using the observer experimental tool for future gamut extension research.