• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
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• pp.1920-1923
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• 2003

This paper presents compression rate improvement for SPIHT algorithm though redundancy bit removing. Proposed SPIHT algorithm uses a method to select of optimized threshold from feature of wavelet transform coefficients and removes sign bit if coefficient of LL area. Experimental results show that the proposed algorithm achieves more improvement bit rate and more fast progressive transmission with low bit rate.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2001년도 춘계학술발표논문집 (하)
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• pp.903-906
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• 2001

점진적 전송 방식은 낮은 해상도의 영상에서부터 점진적으로 더 높은 해상도의 영상으로 전송이 진행되는 동안 수신측에서 전송된 저해상도의 영상으로 영상의 가치를 판단하여 나머지 부분의 전송을 진행하거나 취소 할 수 있어 제한된 전송 대역을 효과적으로 이용할 수 있다. 본 논문에서는 영상의 점진적 전송을 실현하기 위하여 영상을 비트플랜으로 분리한 후 각 플랜에 대하여 상보 쿼드트리 구조로 재구성한 후 적절한 순서에 따라 데이터를 전송하여 전송 초기단계에 영상의 내용을 대체적으로 파악할 수 있도록 하였다.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2003년도 하계학술대회 논문집
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• pp.130-133
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• 2003

본 논문에서는 웨이블렛 압축 기반인 SPIHT 알고리즘의 압축효율을 개선시킬 수 있는 방법을 제안한다. 특히 초기치에서 발생될 수 있는 비트소비를 줄임으로써, 낮은 비트율에서 더욱 빠른 점진적인 전송을 구현하였다. 트리구조에 따르는 최적화 된 임계값 설정과 웨이블렛 변환된 계수들의 계수값을 통해 비트율 향상을 얻을 수 있었다.

• 한국통신학회논문지
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• 제18권11호
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• pp.1618-1625
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• 1993

비손실 라플라시안 파라미드를 이용한 영상 전송에서 최종 재생 영상의 화질은 각 계층별 부호화율과는 상관없이 거의 일정하게 나타난다. 그러나 저 해상도를 갖는 상위 계층에서 재생 영상의 화질은 각 계층별 부호화율에 따라 큰 차이를 나타낸다. 본 논문에서는 상위 계층에서는 우수한 재생 영상을 얻으며, 최종 재생 영상에서는 왜곡을 최소화할 수 있는 계층별 최적 비트 배정 방식을 제안하였다. 제안된 방식에 의한 재생 영상은 기존의 방식에 비해 저 해상도를 갖는 계층에서의 높은 PSNR과 우수한 화질을 나타내므로 보다 효율적인 점진적 영상 전송이 가능하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.88-88
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• 2002

Satellite Image archiving system requires large storage and long transmission time. A simple and cheap way of overcoming these limitations is to increase the compression ratio. However this requires a feasibility study for accurate applications. Here, a new still image compression standard is being developed, the JPEG2000. It provides lossless and lossy compression, progressive transmission by pixel accuracy and by resolution, region-of-interest coding, user-defined tiling size, random codestream access and processing etc. In this study, we will briefly introduce the JPEG2000 compression standard which provides a new compression technique based on the wavelet technology and offers better compression ratios, and evaluate the compression ratios of JPEG2000 for satellite image by performing various image quality tests. Also, we will compare brief test result using the commercial remote sensing software.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제8권1호
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• pp.11-17
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• 2008

Typical wireless sensor networks used in structural monitoring are continuous types wherein data transmission is progressive at all time that may include irrelevant and insignificant data and information. Continuous types of wireless monitoring systems often pose problems of handling large-sized data that may deteriorate the performance of the system. The proposed method is to suggest an event-triggered monitoring system that captures and transmits relevant data only. An error signal generated by the Principal Components Analysis (PCA) is utilized as an index for event detection and selective data transmission. With this new monitoring scheme, the remote server is relieved of unwanted data by receiving only relevant information from the wireless sensor networks. The performance of the proposed scheme was verified with simulation studies.

• ETRI Journal
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• 제33권2호
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• pp.155-162
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• 2011

The scalable extension of the H.264/AVC video coding standard (SVC) demonstrates superb adaptability in video communications. Joint source and channel coding (JSCC) has been shown to be very effective for such scalable video consisting of parts of different significance. In this paper, a new JSCC scheme for SVC transmission over packet loss channels is proposed which performs two-dimensional optimization on the quality layers of each frame in a rate-distortion (R-D) sense as well as on the temporal hierarchical structure of frames under dependency constraints. To compute the end-to-end R-D points of a frame, a novel reduced trellis algorithm is developed with a significant reduction of complexity from the existing Viterbi-based algorithm. The R-D points of frames are sorted under the hierarchical dependency constraints and optimal JSCC solution is obtained in terms of the best R-D performance. Experimental results show that our scheme outperforms the existing scheme of [13] with average quality gains of 0.26 dB and 0.22 dB for progressive and non-progressive modes respectively.

• Journal of Communications and Networks
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• 제2권1호
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• pp.5-17
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• 2000

cdma2000 offers several enhancement as compared to TIA/EIA-95, although it remains fully compatible with TIA/EIA-95 systems and allows for a smooth migration from one to the other-Major new capability include:1)connectivity to GSM-MAP in addition to IP and IS-41 networks; 2) new layering with new LAC and MAC architectures for improved service multiplexing and QoS management and efficient use of radio resource ;3) new bands and band widths of operation in support of various operator need and constraints, as well as desire for a smooth and progressive migration to cdma 2000; and 4) flexible channel structure in support of multiple services with various QoS and variable transmission rates at up to 1 Mbps per channel and 2 Mbps per user. Given the phenomenal success of wireless services and desire for higher rate wireless services. improved spectrum efficiency was a major design goal in the elaboration of cdma2000. Major capacity enhancing features include; 1) turbo coding for data transmission: 2)fast forward link power control :3) forward link transmit diversity; 4) support of directive antenna transmission techniques; 5) coherent reverse link structure; and 6) enhanced access channel operation. As users increasingly rely on their cell phone at work and at home for voice and data exchange, the stand-by time and operation-time are essential parameters that can influence customer's satisfaction and service utilization. Another major goal of cdma2000 was therefore to enable manufacturers to further optimize power utilization in the terminal. Major battery life enhancing features include; 1) improved reverse link performance (i.e., reduced transmit power per information bit; 2) new common channel structure and operation ;3) quick paging channel operation; 4) reverse link gated transmission ; and 5) new MAC stated for efficient and ubiquitous idle time idle time operation. this article provides additional details on those enhancements. The intent is not to duplicate the detailed cdma2000 radio access network specification, but rather to provide some background on the new features of cdma2000 and on the qualitative improvements as compared to the TIA/EIA-95 based systems. The article is focused on the physical layer structure and associated procedures. It therefore does not cover the MAC, LAC, radio resource management [1], or any other signaling protocols in any detail. We assume some familiarity with the basic CDMA concepts used in TIA/EIA-95.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(4)
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• pp.179-182
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• 2001

This paper has been studied a wavelet based still image transmission over the wireless channel. EZW(Embedded Zerotree Wavelet) is an efficient and scalable wavelet based image coding technique, which provides progressive transfer of signal resulted in multi-resolution representation. It reduces therefore the reduce cost of storage media. Although EZW has many advantages, it is very sensitive on error. Because coding are performed in subband by subband, and it uses arithmetic coding which is a kind of variable length coding. Therefore only 1∼2bit error may degrade quality of the entire image. So study of error localization and recovery are required. This paper investigates the use of reversible variable length codes(RVLC) and data partitioning. RVLC are known to have a superior error recovery property due to their two-way decoding capability and data partitioning is essential to applying RVLC. In this work, we show that appropriate data partitioning length for each SNR(Signal-to-Noise Power Ratio) and error localization in wireless channel.

• 한국통신학회논문지
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• 제29권2C호
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• pp.324-332
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• 2004

최근 영상 전체를 전송ㆍ복원하기보다는 영상의 일부 특정 영역이나 사용자 위주의 관심영역(ROI)에 대한 우선적 처리 요구가 웹 브라우징, 이미지 데이터베이스, 원격진료 등과 같은 응용 분야에서 증가하고 있다. 본 논문에서는 기존의 JPEG2000 Part1에서 사용한 Maxshift 방식을 이용하여 둘 이상의 ROI를 가지는 multiple-ROI 코딩 기법을 제안한다. 제안한 기법은 기존의 방식에서처럼 하나의 ROI 뿐만 아니라, multiple ROI를 가지는 영상 전송이 가능함을 보여준다. 또한 웨이브렛 변환(Wavelet Transform)을 이용한 점진적 전송 방식을 사용하기 때문에 낮은 대역폭에서도 사용자가 원하는 ROI를 non-ROI 보다 좀 더 우수한 품질로 전송ㆍ복원 할 수 있고 효율적인 압축이 가능함을 시뮬레이션을 통하여 확인하였다.