• Journal of information and communication convergence engineering
• /
• v.7 no.4
• /
• pp.501-506
• /
• 2009

In the H.264/ AVC video coding standard, the intra-prediction coding with various block sizes offers a considerably high improvement in coding efficiency compared to previous standards. In order to achieve this, H.264/AVC uses the Rate-distortion optimization (RDO) technique to select the best intraprediction mode for a macroblock, and it brings about the drastic increase of the computation complexity of H.264 encoder. To reduce the computation complexity and stabilize the coding performance on visual quality, this paper proposed a fast intra-prediction mode decision algorithm using non-parametric thresholds and simplified directional masks. The use of nonparametric thresholds makes the intra-coding performance not be dependent on types of video sequences and simplified directional masks reduces the compuation loads needed by the calculation of local edge information. Experiment results show that the proposed algorithm is able to reduce more than 55% of the whole encoding time with a negligible loss in PSNR and bitrates and provides the stable performance regardless types of video sequences.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.13 no.3
• /
• pp.461-471
• /
• 1989

For the mixed-mode crack problems the direction of crack growth, the crack path and the rational representation of fatigue crack growth rates should be studied to predict fatigue life and safety of structures. In this study, a round specimen which produce nearly identical effects in all loading directions is proposed to make an easy measurement of initial direction of crack growth. The mode I and mode II stress intensity factors of the specimen were calculated using finite element method, in which the square root singular stresses at the crack tip are modeled by means of four rectangular quarter-point eight-noded elements surrounding the crack tip. Experimental results for high strength aluminum alloy showed that the direction of mixed-mode crack growth agree well with maximum principal stress criterion as well as minimum strain energy density criterion, but not with maximum shear stress criterion. From data of fatigue crack growth rates using crack geometry projected on the line perpendicular to the loading direction it is easily established that mixed-mode fatigue crack growth in 5083-H115 aluminum alloy goes predominantly with mode I crack growth behaviors.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.24 no.1
• /
• pp.40-48
• /
• 2019

Hybrid electric propulsion systems (H-EPSs) are an intermediate step for integrated full electric propulsion warships. H-EPSs are a dynamic combination of mechanical and electrical propulsion systems to achieve the required mission performances. The system modes could adapt to meet the requirement of the various operation conditions of a warship. This paper presents a configuration and operating modes of H-EPSs considering the operation conditions of a destroyer class warship. The system has three propulsion modes, namely, motoring mode, generating mode [power take off (PTO) mode], and mechanical mode. The PTO mode requires a careful fuel efficiency analysis because the fuel consumption rate of propulsion engines may be low compared with the generator's engines depending on the loading power. Therefore, the calculation of fuel consumption according to the operating modes is performed in this study. Although the economics of the PTO mode depends on system cases, it has an advantage in that it ensures the reliability of electric power in case of blackout or minimum generator operation.

• Journal of Broadcast Engineering
• /
• v.15 no.4
• /
• pp.582-590
• /
• 2010

he rate-distortion optimization (RDO) method in the H.264/AVC encoder is a technology that improves the coding efficiency, but increases the computational complexity. In this paper, a fast Intra mode decision algorithm using DCT (Discrete Cosine Transform) coefficients distribution is proposed to reduce the H.264 encoder complexity. The proposed method reduces the encoder complexity on average 68.40%, while the coding efficiency is slightly decreased compared with the H.264/AVC encoder.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.2 no.6
• /
• pp.9-17
• /
• 1994

In this study, a shifting algorithm of CVT was suggested for the two(2) driving modes : (1) power mode and (2) economy mode. Shifting algorithm must be obtained to make the engine run on the optimum operating line for the desired performance of the vehicle. Optimum operating lines of the engine were obtained by connecting the shortest way of the iso-power lines for the power mode and by connecting the shortest way of the BSFC curves for the economy mode. Also dynamic model of CVT vehicle was derived considering the throttle and the brake operation. By using the shifting algorithm and the CVT vehicle model, numerical simulations were performed to estimate the performance of CVT. Simulation results showed that comparing the performance of the conventional 4-speed automatic transmission, acceleration performance of the CVT vehicle was almost same with the AT vehicle for the power mode and the fuel economy of CVT was 14% superior than that of AT for the economy mode.

• Proceedings of the KIEE Conference
• /
• 1999.11c
• /
• pp.612-614
• /
• 1999

In this paper a novel sliding mode control is proposed by using $H_2/H_{\infty}$ controller. this technique is constructed based on the augmented system with a virtual state and make it has the dynamics of the original system and then $H_2/H_{\infty}$ controller has robust characteristics of sliding mode control for existing parameter uncertainty. The reaching phase is excluded by setting initial virtual state value appropriately.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.3C
• /
• pp.250-257
• /
• 2006

In this paper, we propose an efficient algorithm for the RDO mode decision in H.264/AVC encoder. Based on the properties of DCT coefficients and the RDO mode decision processing, we derive a new condition for detecting an error block having all-zero DCT coefficient (AZCB). (I)DCT, (I)Q, and entropy coding are skipped for AZCBs in the proposed algorithm. It makes the reduction of the computational complexity for the RDO mode decision. Simulation results show that the proposed algorithm achieves computational saving over 40% compared to the conventional method.

• Proceedings of the KIEE Conference
• /
• 1998.07f
• /
• pp.1879-1881
• /
• 1998

The conducted differential mode (DM) EMI in a flyback converter are analyzed. Circuit modeling of passive components and PCB pattern for the EMI simulation are presented. Using the model, high frequency noise path is analyzed. The analyses are verified with simulations by identifying the peakings of the EMI pattern.

• Proceedings of the IEEK Conference
• /
• 2007.07a
• /
• pp.265-266
• /
• 2007

New coding tools require the increase of the encoder complexity in H.264. In this paper we propose a fast mode decision method to reduce the computational complexity of mode decision. The simulation results shows that the proposed methods could reduce the coding time of overall sequences by 30% on average without any noticeable degradation of the coding efficiency.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.44 no.3
• /
• pp.88-96
• /
• 2007

H.264 is a new international video coding standard that can achieve considerably higher coding efficiency than conventional standards. Its coding gain has been achieved by employing advanced video coding methods. Specially, the increased number of macroblock modes and the complex mode decision procedure using the Lagrangian optimization are the main factors for increasing coding efficiency. Although H.264 obtains improved coding efficiency, it is difficult to do an real-time encoding because it considers all coding parameters in the mode decision procedure. In this paper, we propose a fast mode decision algorithm which classifies the macroblock modes in order to determine the optimal mode having low complexity quickly. Simulation results show that the proposed algorithm can reduce the encoding time by 34.95% on average without significant PSNR degradation or bit-rate increment. In addition, in order to show the validity of simulation results, we set up a low boundary condition for coding efficiency and complexity and show that the proposed algorithm satisfies the low boundary condition.