• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.21 no.8
• /
• pp.2033-2042
• /
• 1996

In this papre, we describe a recently implemented echo canceller for digital cellular communication of Code Division Multiple Access(CDMA) that features time sharing of digital signal processor(DSP) over four channels in one DSP to reduce per channel costs. In the Public Land Mobile Network(PLMN), it is important to cancel the echo reflected from the Public Switched Telephone Network(PSTN) side. In case of digital mobile system, the round-trip delay of the echo is in excess of about 180 milliseconds due to frame-by-frame voice coding. It is necessary to cancel the echo in PLMN. We have developed a multi-channel echo canceller tht operates with Time Switch Module in a Mobile Switching Center(MSC). The general echo canceller needs PCM trunk interface circuits and the tone detection and disabling circuits, but the multi-channel echo canceller linked with Time Switch Module does not need them. Therefore we could develop the effective and economical echo canceller.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.49 no.9
• /
• pp.92-103
• /
• 2012

In this paper, we discuss and propose a new algorithm of coding technique for scalably servicing holographic video in various decoding environment. The proposed algorithm consists of the hologram-based resolution scalable coding (HRS) and the light source-based SNR scalable coding (LSS). They are classified by the method generating and capturing hologram. HRS is a scalable coding technique for the optically captured hologram and LSS is one for the light source before generating hologram. HRS can provide the scalable service of 8 steps with the compression ratio from 1:1 to 100:1 for a $1,024{\times}1,024$ hologram. LSS can also provide the various service depending on the number of the light source division using lossless compression. The proposed techniques showed the scalable holographic video service according to the display with the various resolutions, computational power of the receiving equipment, and the network bandwidth.

• 제어로봇시스템학회:학술대회논문집
• /
• 1991.10a
• /
• pp.337-341
• /
• 1991

Fieldbus is a low level serial digital network which will be used for factory automation. This paper describes lower layer implementation of a Fieldbus network interface. Physical layer provides hardware interface between IBM-PC and Fieldbus. Also, physical layer uses manchester coding, shielded twisted pair lines and RS-485 electrical standard. Data link layer includes Intel's iDCX96 real time executive for 8797 one chip microcontroller and Fieldbus data link protocol software.

• Journal of Korea Multimedia Society
• /
• v.19 no.8
• /
• pp.1487-1497
• /
• 2016

Explosively growing service of digital multimedia data increases the need for highly scalable low-cost storage. This paper proposes the new storage architecture based on torus network which does not need network switch and erasure coding for efficient storage usage for high scalability and efficient disk utilization. The proposed model has to compensate for the disadvantage of long network latency and network processing overhead of torus network. The proposed storage model was compared to two most popular distributed file system, GlusterFS and Ceph distributed file systems through a prototype implementation. The performance of prototype system shows outstanding results than erasure coding policy of two file systems and mostly even better results than replication policy of them.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.4 no.1
• /
• pp.56-62
• /
• 2004

This research attempts to suggest a detecting method for cutting position of an object using the neural network, which is one of intellectual methods, and the digital image processing method. The extraction method of object information using the image data obtained from the CCD camera as a replacement of traditional analog sensor thanks to the development of digital image processing. Accordingly, this research determines the threshold value in binary-coding of an input image with the help of image processing method and the neural network for the real-time gray-leveled input image in substitution for lighting; as a result, a specific position is detected from the processed binary-coded image and an actual system designed is suggested as an example.

• Journal of Broadcast Engineering
• /
• v.10 no.4 s.29
• /
• pp.515-527
• /
• 2005

A next-generation codec should be developed to be a scalable video codec(SVC) that not only maximizes the coding efficiency but also adaptively copes with the various communication devices and the variation of network environments. To meet these requirements, Joint Video Team (JVT) of ISO/IEC and ITU-T is standardizing H.264/AVC based SVC. In this paper, we introduce research directions and status on SVC standardization and also analyze techniques and algorithms adopted in the current SVC.

• Journal of Digital Contents Society
• /
• v.17 no.2
• /
• pp.89-96
• /
• 2016

SVC(Scalable Video Coding), which is one form among video encoding technologies, makes video streaming with the various frame rate, resolution, and video quality by combining three different scalability dimensions: temporal, spatial, and video quality scalability. As the above SVC-encoded video streaming consists of one base layer and several enhancement layers, and a wireless AP(Access Point) chooses and sends a suitable layer according to the received power from the receiving terminals in the changeable wireless network environment, the receiving terminals supporting SVC are able to receive video streaming with the appropriate resolution and quality according to their received powers. In this paper, after the performance analysis for the received power, packet loss rate, PSNR(Required Peak Signal to Noise Ratio), video quality level and amount of received video data based on the number of SVC layers was performed, an efficient method for selecting the number of SVC layer satisfying the RSNR and minimizing the amount of received video data is proposed.

• Journal of Broadcast Engineering
• /
• v.12 no.6
• /
• pp.542-554
• /
• 2007

Seamless streaming of multimedia content via heterogeneous networks to viewers using a variety of devices has been a desire for many multimedia services, for which the multimedia contents should be adapted to usage environments such as network characteristics, terminal capabilities, and user preferences. Scalability in video coding is one of attractive features to meet dynamically changing requirements of heterogeneous networks. Currently a new scalable video coding (SVC) is standardizing in the Joint Video Team (JVT) of the ISO/IEC Moving Picture Experts Group (MPEG) and the ITU-T Video Coding Experts Group (VCEG), which will be released as Extension 3 of H.264/MPEG-4 AVC. In this paper, we introduce new technologies of SVC and evaluate performance of it especially regarding on overhead bit-rate and coding efficiency to support spatial, temporal, and quality scalability.

• The Journal of the Korea Contents Association
• /
• v.12 no.4
• /
• pp.10-19
• /
• 2012

Seamless streaming of multimedia content that ensures Quality of Service over heterogeneous networks has been a desire for many multimedia services, for which the multimedia contents should be adapted to usage environments such as network characteristics, terminal capabilities, and user preferences. Scalability in video coding is a good feature to meet the requirement of heterogeneous networks. In this paper, we propose a dynamic adaptation scheme of H.264/AVC SVC bit-stream using the MPEG-21 Digital Item Adaptation (DIA) tool. MPEG-21 DIA framework provides systematic solutions in choosing an adaptation operation to given conditions and supports interoperable video adaptation. The experiment results show that the proposed adaptation scheme provides QoS-enabled delivery and consumption of SVC with time-varying constraints of network, terminal, and user preference, in a robust and efficient way. In particular, the proposed adaptation scheme is proved to work well with very low delay under the condition that the variation rate of the given network bandwidth is upto 62%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.2
• /
• pp.176-187
• /
• 2002

The digital Audio Broadcasting (DAB) system adopts Coded OFDM(COFDM) for channel coding. The COFDM is a combined technique of multicarrier transmission(OFDM) and punctured convolutional coding with viterbi error correction. Because the channel coding is an important topic for OFDM systems, this paper proposes a new turbo coded OFDM system that replaces the existing RCPC codec by a turbo codec without modifying the puncturing procedure and puncturing vectors defined in the standard DAB system for compatibility. The performance of a new system is compared to that of the conventional system under the frequency selective Rician fading channel and the frequency selective Rayleigh fading channel in conjunction with DAB transmission mode I suitable for the terrestrial single frequency network(SFN) broadcasting. The standard system's performance was improved with the aid of turbo codec.