• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6C
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• pp.602-608
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• 2003

In this paper, we propose an efficient DCT calculation method for fast video encoding. We show that the SAD obtained in the motion estimation and compensation process is decomposed into the positive and negative terms. Based on a theoretical analysis, it is shown that the DCT calculation is classified into 4 cases - DCT Skip, Reduced_DCT1 , Reduced_DCT2, and original DCT- according to the positive and negative terms. In the proposed algorithm, one of 4 cases is used for DCT in order to reduce the computational complexity. The simulation results show that the proposed algorithm achieves computational saving approximately 25.2% without image degradation and computational overhead.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.7
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• pp.107-118
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• 2015

Although most current video coding standards set a fixed motion vector resolution like quarter-pel accuracy, a scheme supporting multiple motion vector resolutions can improve the coding efficiency of video since it can allow to use just required motion vector accuracy depending on the video content and at the same time to generate more accurate motion predictor. However, the selected motion vector resolution for each motion vector is a signaling overhead. This paper proposes a contradiction testing-based signaling scheme of the motion vector resolution. The proposed method selects a best resolution for each motion vector among multiple candidates in such a way to produce the minimum amount of coded bits for the motion vector. The signaling overhead is reduced by contradiction testing that operates under a predefined criterion at both encoder and decoder with a purpose of pruning irrelevant candidate motion vector resolutions from signaling responsibility. Experimental results verified that the proposed scheme is effective in reducing coded motion information by achieving its $Bj{\o}ntegaard$ delta bit rate (BDBR) gain of about 4.01% on average (and up to 15.17%) compared to the conventional scheme with a fixed motion vector resolution.

• Journal of KIISE:Software and Applications
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• v.36 no.8
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• pp.616-622
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• 2009

Thanks to Dynamic Capacitance Control (DCC) technique, response time of an LCD display has greatly improved. However, DCC requires hi-speed memory for the real-time writing/reading of an image of a previous frame, which results in increases in hardware overhead and cost. In this paper, we propose Modified Exponential Golomb (MEG) coding, a low-complex high-speed image compression method, which can remarkably reduce memory requirement for DCC. We also propose a pixel-wise DCC switching technique to prevent a compression error from affecting the quality of a final image on LCD. In our experiment, the degradation in visual quality was not noticeable when we cut the DCC memory size of 1080i HD data by 1/3.

• Journal of Broadcast Engineering
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• v.6 no.2
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• pp.121-130
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• 2001

We propose an efficient DCT-domain video transcoding algorithm for flexible for bit-rate video communications. Video transcoding provides communication fiexibility by adaptively changing the bit-rate of compressed bit stream. During the transcoding process, adrift error is unavoidable because of the difference between reference images in the series of encoding and decoding. For solving the drift error problem, cascade pixel-domain transcoder (CPDT) has been proposed. CPDT, however, requires highly complex hardware and heavy computational overhead. In this paper we propose a DCT-domain transcoding technique, which enables efficient transcoding without any drift error. The proposed cascade DCT-domain transcoder (CDDT) is realized by new motion compensation and down-sampling methods in the DCT-domain.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3A
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• pp.237-246
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• 2007

Clock Synchronization is one of the most basic factors to be considered when we implement an indoor synchronization network for indoor positioning. In this paper, we present a new synchronization algorithm which does not employ time stamps in order to reduce the hardware complexity and data overhead. In addition to that, we describe an algorithm that is designed to compensate the frequency drift giving an serious impact on the synchronization performance. The performance evaluation of the proposed algorithm is achieved by investigating MTIE (Maximum Time Interval Error) values through simulations. In the simulations, the frequency drift values of the practical oscillators are used. From the simulation results, it is investigated that we can achieve the synchronization performance under 10 ns when we use 1 second synchronization interval with 1 ns resolution and TCXOs (Tmperature Compensated Cristal Oscillators) both in the master clock and the slave clock.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.1
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• pp.35-44
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• 2006

The area of ad hoc networking has been receiving increasing attention among researchers in recent years and a variety of routing protocols targeted specifically at the ad hoc networking environment have been proposed. Selfish nodes are those which do not perform certain operations that the protocol specifies that they should, through a wish to conserve power. We propose a scheme as a mean to mitigate the detrimental effect of selfish nodes. We also propose a new area that might affect nodes' behavior - the environment's influence. In order to let nodes fairly be able to communicate in the networks we proposed solution to this problem. And our scheme can be applied to other reputation methods. We also contain the simulation results in our paper, and through the result, we can conclude that we can solve the problem by adding a little overhead.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.3
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• pp.189-199
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• 2004

A bridge transported servo manipulator (BTSM) system for the advanced spent fuel conditioning process (ACP) has been developed to overcome the limitation of access, which is a drawback of mechanical master-slave manipulators (MSM) for the equipment maintenance. The servo manipulator is composed of a slave manipulator attached to the telescoping tubesets equipped with the overhead bridge installed at a hot cell and a master manipulator installed at an out-of-hot cell. Each manipulator has 7 degrees-of-freedom (DOF): a body rotation, an upper-arm tilt, a lower-arm tilt, a lower-arm rotation, a wrist pan & tilt, and a grasp motion. A wire-driven mechanism for a lower-arm rotation, a wrist pan and tilt, and a grasp motion of the manipulator has been adopted to increase the handling capacity compared to the manipulator weight and decrease the friction. The main disadvantage of the wire-driven mechanism is that if one link is in motion, other links can be affected. In this paper, the transmission characteristics among the wire-driven links have been formulated to overcome this drawback. The unexpected behaviors are confirmed by analyses of transmission characteristics as well as experiments. Also, the experimental results show that the unexpected behaviors are greatly decreased by the proposed compensation equations.