• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.2 s.314
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• pp.1-11
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• 2007

H.264/AVC uses variable block sizes to achieve significant coding gain. It has 7 different coding modes having different motion compensation block sizes in Inter slice, and 2 different intra prediction modes in Intra slice. This fine-tuned new coding feature has achieved far more significant coding gain compared with previous video coding standards. However, extremely high computational complexity is required when rate-distortion optimization (RDO) algorithm is used. This computational complexity is a major problem in implementing real-time H.264/AVC encoder on computationally constrained devices. Therefore, there is a clear need for complexity reduction algorithm of H.264/AVC such as fast mode decision. In this paper, we propose a fast mode decision with early $P8\times8$ mode rejection based on block size activity using large block history map (LBHM). Simulation results show that without any meaningful degradation, the proposed method reduces whole encoding time on average by 53%. Also the hybrid usage of the proposed method and the early SKIP mode decision in H.264/AVC reference model reduces whole encoding time by 63% on average.

• Korean Journal of Optics and Photonics
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• v.7 no.3
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• pp.251-259
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• 1996

Two-Photon Fluorescence (TPF) experiment measures temporal width of an amplified short laser pulse which has passed through a four-pass Nd: glass amplifier, after selecting a single pulse from pulse train Q-switched and mode-locked(QSML) in Nd:YLF master oscillator. Determination of pulsewidth and pulseshape was also made with detection of autocorrelation trace of CW mode-locked pulse train by using noncollinear type I Second Harmonic Generation (SHG) method. The observed TPF track showed various patterns, depending on pulse-selecting position in QSML pulse train. That is, autocorrelation of a pulse extracted at front of the train displayed smooth pulse shape, while one from the trailing part of the train created many sharp spikes and substructure in the pulse. By TPF method, pulsewidth was measured to be 44.4 ps with contrast ratio of 2.86 which enabled us to find out energy fraction of a pulse to total energy, (sum of pulse and background); we obtain the value of 0.62. Pulsewidth of 46.6ps was also acquired in another SHG experiment with the help of only mode-locked pulse train. On the other hand, we confirmed that shape of the pulse is close to $sech^2$ one as a result of fitting the SHG autocorrelation signal with various functions. With simulation using this $sech^2$ type of pulse, pulsewidth reduction of the beam, having passed through four-pass amplifier, was also verified.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.7
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• pp.739-747
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• 2007

Dual-mode bandpass filter was designed by using periodic stepped impedance ring resonator with step perturbation. The periodic stepped impedance ring resonator has the effects of size reduction and $2^{nd}$ harmonic suppression by changing characteristic impedance ratio. The perturbation for dual-mode generation was also easily controlled by characteristic impedance ratio, and the variation of dual-mode resonant frequencies and attenuation pole frequencies were analyzed by the effect of step perturbation. Chip capacitors were used for input/output coupling, and the variation of center frequency by the coupling capacitance and step perturbation was also considered. From the results, two types of 2 GHz dual-mode bandpass filter were fabricated in size of $14{\times}14mm^2$, those have different attenuation poles and bandwidths. The measured results of proposed bandpass filters showed a good agreement with the calculated estimations, and those have insertion loss of 2.52, 0.52 dB and 3 dB bandwidth of 4.03, 15.02 %, respectively.

• Journal of Broadcast Engineering
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• v.12 no.4
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• pp.360-372
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• 2007

We propose a fast inter-layer mode decision method by utilizing coding information of base layer upward its enhancement layer inscalable video coding (SVC), also called MPEG-4 part 10 Advanced Video Coding Amendment 3 or H.264 Scalable Extension (SE) which is being standardized. In this paper, when the motion vectors from the base layer have zero motion (0, 0) in inter-layer motion prediction or the Integer Transform coefficients of the residual between current MB and the motion compensated MB by the predicted motion vectors from the base layer are all zero, the block mode of the corresponding block to be encoded at the enhancement layer is determined to be the $16{\times}16$ mode. In addition, if the predicted mode of the MB to be encoded at the enhancement layer is not equal to the $16{\times}16$ mode, then the rate-distortion optimization is only performed on the reduced candidated modes which are same or smaller partitioned modes. Our proposed method exhibits the complexity reduction in encoding time up to 72%. Nevertheless, it shows negligible PSNR degradation and bit rate increase up to 0.25dB and 1.73%, respectively.

• Journal of KIISE:Information Networking
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• v.31 no.5
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• pp.532-543
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• 2004

Mobile Ad hoc NETworks (MANET) consist of mobile nodes which are usually powered by battery Approaches for minimizing power consumption have been proposed for all network layers and devices. IEEE 802.11 DCF (Distributed Coordination Function), a well-known medium access control protocol for MANETS, also defines a power save mode operation. The nodes in power save mode periodically repeat the awake state and the doze state in synchronized fashion. When all nodes are in the awake state, the exchange the announcements for the subsequent message transmission with neighbors. The nodes that send or receive the announcements stay awake for data transmission, and others go into the dole state. The previous works for enhancing the power save mode operation have focused on shortening the duration of the awake state. We observed that the longer sleeping period results in seriously long delivery latency and the consequent unnecessary power consumption as well, because the packets can move forward only one hop for a fixed interval. In this paper, we propose an improved protocol for the power save mode of IEEE 802.11 DCF, which allows the flooding packets to be forwarded several hops in a transmission period. Our approach does not reduce the duration of compulsory awake period, but maximizes its utilization. Each node propagates the announcements for next flooding to nodes of several hops away, thus the packets can travel multiple hops during one interval. Simulation results of comparison between our scheme and the standard show a reduction in flooding delay maximum 80%, and the unicasting latency with accompanying flooding flows near 50%, with slight increase of energy consumption.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.1
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• pp.124-132
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• 2013

Damage location and extent could be detected by the inverse analysis on dynamic response of the damaged structure. In general, detection of damage location is possible by the observation of the mode shape difference between undamaged and damaged structure and assessment of stiffness reduction is possible by the observation of the natural frequency difference of them. The study on damage detection by the dynamic response in civil structures is reported enough and in practical use, but in building structures it is reported seldom due to several problems. The purpose of this study is to present the damage detection method on shear building structures by mode shape. The damage location index using 1st mode shape is observed theoretically to find out damage location. The damage detection method is applied to numerical analysis model such as MATLAB and MIDAS GENw for the verification. Finally the shaking table test on 3 story shear building is performed for the examination of the damage detection method. In shaking table results, as the story stiffness decrease by 25% the 1st mode frequency increase by 12%, and the damage location index represents minus at damaged story.

• Structural Engineering and Mechanics
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• v.78 no.1
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• pp.41-52
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• 2021

Inelastic static pushover analysis has been used in the academic-research widely for seismic analysis of structures. Nowadays, the variety pushover analysis methods have been developed, including Modal pushover, Adaptive pushover, and Cyclic pushover, in which some weaknesses of the conventional pushover method have been rectified. In the conventional pushover analysis method, the effects of cumulative growth of cracks are not considered on the reduction of strength and stiffness of RC members that occur during earthquake or cyclic loading. Therefore, the Cyclic Pushover Analysis Method (CPA) has been proposed. This method is a powerful technique for seismic evaluation of regular reinforced concrete buildings in which the first mode of them is dominant. Since the bridges have different structures than buildings, their results cannot necessarily be attributed to bridges, and more research is needed. In this study, a cyclic pushover analysis with four loading protocols (suggested by valid references) by the Opensees software was conducted for seismic evaluation of two regular reinforce concrete bridges. The modeling method was validated with the comparison of the analytical and experimental results under both cyclic and dynamic loading. The failure mode of the piers was considered in two-mode of flexural failure and also a flexural-shear failure. Along with the cyclic analysis, conventional analysis has been studied. Also, the nonlinear incremental dynamic analysis (IDA) method has been used to examine and compare the results of pushover analyses. The time history of 20 far-field earthquake records was used to conduct IDA. After analysis, the base shear vs. displacement in the middle of the deck was drawn. The obtained results show that the cyclic pushover analysis method is able to evaluate an accurate seismic behavior of the reinforced concrete piers of the bridges. Based on the results, the cyclic pushover has proper convergence with IDA. Its accuracy was much higher than the conventional pushover, in which the bridge piers failed in flexural-shear mode. But, in the flexural failure mode, the results of each two pushover methods were close approximately. Besides, the cyclic pushover method with ACI loading protocol, and ATC-24 loading protocol, can provided more accurate results for evaluating the seismic investigation of the bridges, specially if the bridge piers are failed in flexural-shear failure mode.

• Journal of Dental Rehabilitation and Applied Science
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• v.20 no.1
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• pp.19-29
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• 2004

The purpose of this study was to compare the fracture strength of the IPS Empress ceramic crown according to the incisal reduction(2.0mm, 2.5mm, 3.0mm) and axial inclination ($4^{\circ}$, $8^{\circ}$, $12^{\circ}$) of the lower canine. After 10 metal dies were made for each group, the IPS Empress ceramic crowns were fabricated and each crown was cemented on each metal die with resin cement. The cemented crowns mounted on the testing jig were inclined 30 degrees and a universal testing machine was used to measure the fracture strength. The results of this study were as follows : 1. The fracture strength of the ceramic crown with 3.0mm depth and $12^{\circ}$ inclination was the highest(1377N). Crowns of 2.0mm depth and $4^{\circ}$ inclination had the lowest strength (731 N). 2. There were no significant differences of the fracture strength by axial inclination in same incisal reduction group. 3. The fracture mode of the crowns was similar. Most of fracture lines began at the loading area and extended through proximal surface perpendicular to the margin irrespective of incisal reduction.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.1
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• pp.95-105
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• 2012

The selective catalytic reduction (SCR) system is a highly-effective aftertreatment device for NOx reduction of diesel engines. Generally, the ammonia ($NH_3$) was generated from reaction mechanism of SCR in the SCR system using the liquid urea as the reluctant. Therefore, the precise urea dosing control is a very important key for NOx and $NH_3$ slip reduction in the SCR system. This paper investigated NOx and $NH_3$ emission characteristics of urea-SCR dosing system based on model-based control algorithm in order to reduce NOx. In the map-based control algorithm, target amount of urea solution was determined by mass flow rate of exhaust gas obtained from engine rpm, torque and $O_2$ for feed-back control NOx concentration should be measured by NOx sensor. Moreover, this algorithm can not estimate $NH_3$ absorbed on the catalyst. Hence, the urea injection can be too rich or too lean. In this study, the model-based control algorithm was developed and evaluated on the numerical model describing physical and chemical phenomena in SCR system. One channel thermo-fluid model coupled with finely tuned chemical reaction model was applied to this control algorithm. The vehicle test was carried out by using map-based and model-based control algorithms in the NEDC mode in order to evaluate the performance of the model based control algorithm.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.9
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• pp.878-885
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• 2009

One of important factors in designing MEMS resonators for RF filters is obtaining a desired frequency response function (FRF) within a specific frequency range of interest. Because various array-type MEMS resonators have been recently introduced to improve the filter characteristics such as bandwidth, pass-band, and shape factor, the degrees of freedom (DOF) of finite elements for their FRF calculation dramatically increases and therefore raises computational difficulties. In this paper the Krylov subspace-based model order reduction using moment-matching with non-zero expansion points is represented as a numerical solution to perform the frequency response analyses of those array-type MEMS resonators in an efficient way. By matching moments at a frequency around the specific operation range of the array-type resonators, the required FRF can be efficiently calculated regardless of their operating frequency from significantly reduced systems. In addition, because of the characteristics of the moment-matching method, a minimal order of reduced system with a prearranged accuracy can be determined through an error indicator using successive reduced models, which is very useful to automate the order reduction process and FRF calculation for structural optimization iterations. We also found out that the presented method could obtain the FRF of a $6\times6$ array-type resonator within a seventieth of the computational time necessary for the direct method and in addition FRF calculation by the mode superposition method could not even be completed because of a data overflow with a half after calculation of 9,722 eigenmodes.