• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권11호
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• pp.4443-4462
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• 2020

This paper proposes a new framework of reversible data hiding scheme for absolute moment truncation coding (AMBTC) compressed images. AMBTC-based RDH can be applied to optical remote sensing (ORS) image transmission, which achieves target region preservation and image compression simultaneously. Existing methods can be concluded as two types. In type I schemes, stego codes mimic the original AMBTC format where no file bloat occurs, yet the carried secret data is limited. Type II schemes utilize predication errors to recode quantity levels of AMBTC codes which achieves significant increase in embedding capacity. However, such recoding causes bloat inside stego format, which is not appropriate in mentioned ORS transmission. The proposed method is a novel type I RDH method which prevents bloat inside AMBTC stego codes with significant improvement in embedding capacity. The AMBTC compressed trios are grouped into two categories according to a given threshold. In smooth trio, the modified low quantity level is constructed by concatenating Huffman codes and secret bits. The reversible contrast mapping (RCM) is performed to complex trios for data embedment. Experiments show that the proposed scheme provides highest payload compared with existing type I methods. Meanwhile, no expansion inside stego codes is caused.

• Journal of the Optical Society of Korea
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• 제20권4호
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• pp.464-469
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• 2016

All-optical non-return-to-zero (NRZ) -to- return-to-zero (RZ) data-format conversion has been successfully demonstrated using a semiconductor optical amplifier in a fiber-loop mirror (so-called SOA-loop mirror) with a continuous-wave (CW) holding beam. The converted RZ signal after pulse compression has been used to create a 40 Gb/s OTDM (Optical Time Division Multiplexing) signal. Here is proposed an NRZ-to-RZ conversion method without any additional optical clocks, unlike conventional methods based on optical AND logic. In addition, it has the merit of operating at various bit-rate speeds without any controlling device. Moreover, it has a simple structure, and it can be used for all-optical bit-rate-flexible clock recovery.

• ETRI Journal
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• 제29권5호
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• pp.655-666
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• 2007

There are nodes and edges in a topological map. Node data has been used as a main source of information for the localization of mobile robots. In contrast, edge data is regarded as a minor source of information, and it has been used in an intuitive and heuristic way. However, edge data also can be used as a good source of information and provide a way to use edge data efficiently. For that purpose, we define a data format which describes the shape of an edge. This format is called local generalized Voronoi graph's angle (LGA). However, the LGA is constituted of too many samples; therefore, real time localization cannot be performed. To reduce the number of samples, we propose a compression method which utilizes wavelet transformation. This method abstracts the LGA by key factors using far fewer samples than the LGA. Experiments show that the LGA accurately describes the shape of the edges and that the key factors preserve most information of the LGA while reducing the number of samples.

• 한국생활과학회지
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• 제24권1호
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• pp.97-109
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• 2015

Recently, because the market for compression wear now includes all consumers, not just professionals, various items for recovery after exercising or for enhanced effects from exercise have been introduced. In this research, a systematic and stepwise design process was proposed to develop compression garment that has both functional area and appropriate pressure to protect the knee when exercising. The U-V format functional area that wraps underneath the knee was selected by considering the shape and change in the skin length when bending the knee. After the selection of the functional area, a total of seven knee design areas, including the existing product, were designed to determine the appropriate pressure. After various movements, the compression garment was ranked in terms of support of the knee, level of pressure, discomfort of seam line, and comfort of popliteal; the preferred design was selected using the quad method. Four compression wear garments were produced using two selected preferred designs; the wear evaluation was performed using a seven-point Likert scale. As a result, the optimal reduction rate of the pattern was calculated based on Ziegert and Keil's method. The applied percentage of the fabric stretch at the upper part of the crotch was 66% for the width and 50% for the length; for the lower part of the crotch, only 66% for the width was applied. Moreover, it was determined that the design of the U-V knee protection part was preferred when a 7 mm square was placed at a 1 mm distance because this not only supports the knee but also allows the fabric to accommodate various skin deformations.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권5호
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• pp.605-614
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• 2016

We develop a novel SAD circuit for power-efficient H.264 encoding, namely a-SAD. Here, some highest-order MSB's are approximated to single MSB. Our theoretical estimations show that our proposed design simultaneously improves performance and power of SAD circuit, achieving good power efficiency. We decide that the optimal number of approximated MSB's is four under 8-bit YUV-420 format, the largest number not to affect video quality and compression-rate in our video experiments. In logic simulations, our a-SAD circuit shows at least 9.3% smaller critical-path delay compared to existing SAD circuits. We compare power dissipation under iso-throughput scenario, where our a-SAD circuit obtains at least 11.6% power saving compared to other designs. We perform same simulations under two- and three-stage pipelined architecture. Here, our a-SAD circuit delivers significant performance (by 13%) and power (by 17% and 15.8% for two and three stages respectively) improvements.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.98.2-98
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• 2001

It is necessary to have enough transmission capacity for advanced internet techniques and various digital home appliances networking. Home appliances interface IEEE1394 technique has much wealthy transmission skill. IEEE1394 is using home appliances through various information form image and voice change data real time print out. In this paper, AVC CTS technology and IEEE1394 technology are introduced. Digital Video Camera includes compression format using DV. System composition control is consisted of protocols like IEC-61883 and AV/C command set standard.

• 대한의용생체공학회:의공학회지
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• 제12권3호
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• pp.215-222
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• 1991

In this paper, we present a result of our study on how to construct a pilot MPACS (medical hic lure archiving and communication System) based on X -Window system. The proposed MPACS Is composed of image acquisition units, image archiving and processing units, display units, and all units are Interfaced with a LAN The image management is done according to the TIFF (Tagged Image File Format) , and the dis- play system is built upon generally accepted software packages, namely the X -Window system. Also, lossless and lossy digital image compression methods were implemented and tested with X -ray and CT images.

• 한국항행학회논문지
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• 제18권4호
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• pp.401-408
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• 2014

하둡(Hadoop)은 맵리듀스(MapReduce) 분산처리 프로그래밍 모델과 HDFS(Hadoop distributed file system) 분산 파일시스템으로 구성된다. 하둡은 빅데이터 처리에 적합한 프레임워크로서, 대량의 스몰파일 처리에 문제점이 있다. 하둡에서 대량의 스몰파일 처리는 하나의 파일마다 매퍼가 생성되며, 파일의 메타정보를 저장하기 위해 많은 메모리가 필요한 문제점이 있다. 본 논문은 하둡 플랫폼에서 다양한 방법으로 대량의 스몰파일 처리방법을 비교 검토하였다. 일반 압축은 데이터의 크기와 상관없이 하나의 매퍼로 처리해야 하기 때문에, 하둡 처리 포맷으로 적절하지 않다. 시퀀스 와 하둡 아카이브 파일의 처리는 스몰파일을 압축 및 병합을 통해 네임노드의 메모리 문제가 제거되었다. 하둡 아카이브 파일은 스몰파일의 병합시간이 시퀀스 파일보다 빠른 속도를 보였다. CombineFileInputFormat 클래스를 이용한 처리는 병합과정이 필요 없으며, 빅데이터 처리방법과 유사한 속도를 보였다.

• 정보보호학회논문지
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• 제27권5호
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• pp.1107-1115
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• 2017

압축파일 형식으로 가장 많이 쓰이는 PKZIP형식은 ZIP 파일뿐만 아니라 MS Office 파일과 안드로이드 스마트폰의 어플리케이션 파일 등에서 사용되는 파일형식이다. 이처럼 다양한 영역에서 널리 쓰이는 PKZIP 형식의 파일은 디지털 포렌식 관점에서 구조분석이 필수적이고 파일이 손상된 경우 복구를 할 수 있어야 한다. 하지만 기존 연구들의 경우 ZIP 파일에서 사용하는 Deflate 압축 알고리즘이 적용된 데이터를 복구하거나 의미 있는 데이터를 추출해 내는 것에만 초점이 맞춰져 있다. 비록 대부분의 데이터가 ZIP 파일의 압축된 데이터에 존재하지만 그 외의 영역에서도 포렌식적으로 의미 있는 데이터가 존재하기 때문에 정상적인 ZIP 파일 형태로 복구를 해야 한다. 따라서 본 논문에서는 손상된 ZIP 파일이 주어졌을 때 이를 정상적인 형태의 ZIP 파일로 복구하는 기법을 제시한다.

• 한국통신학회논문지
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• 제30권5C호
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• pp.406-414
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• 2005

디지털 컨텐츠, 특히 정보 집약성이 큰 특성으로 인해 가장 선호되는 영상/비디오 컨텐츠에 대한 저작권보호 기술의 필요성이 크게 대두되고 있다. 이러한 문제를 해결하기 위해 본 논문에서는 가장 비전 있는 기술로 인식되는 디지털 워터마킹 알고리즘을 제안하였다. 본 알고리즘은 MPEG 압축 시스템을 대상으로 하였고 워터마킹 과정은 압축 과정 중에 수행되며 워터마크는 I 프레임의 명암성분에 삽입된다. 실험 결과에서는 제안된 방법이 여러 공격에 대해서 비가시성과 강인성을 모두 만족하는 것을 보였고 워터마킹 과정을 수행한 압축된 이미지들과 수행하지 않은 압축된 이미지들(색차 포맷 Y:Cb:Cr=4:2:0을 사용하는 TM-5 기반 압축에 대해서 평균 압축률이 약 27:1 이었다)사이의 평균 PSNR의 차가 단지 1.8dB($4.2\%$)의 낮은 값이 측정되었다. 공격 후에 영상을 재사용할 수 있는 경우에 대해서는 추출된 워터마크와 원 워터마크의 정규화 상관도가 0.8 이상의 높은 값이 측정되었다.