• Journal of the Earthquake Engineering Society of Korea
• /
• v.9 no.1 s.41
• /
• pp.25-32
• /
• 2005

Seismic load is distributed to modes of a structure through the modal participation factor(MPF). The modal participation factor is essential to analyze structural response under earthquake load. MPF of a real structure differs from that of analytical mathematical model due to the error induced from analytical assumptions and during the construction. In this study, an identification method is proposed to calculate the 1st MPF of real structure based on $H^{\infty}$ optimal model reduction. The MPF is obtained from the relationship between observability and controllability matrices realized from system identification and those of a prototype 2-degree state space model. The proposed method is verified thorough numerical examples.

• Journal of Broadcast Engineering
• /
• v.19 no.2
• /
• pp.158-165
• /
• 2014

High Efficiency Video Coding (HEVC), the latest video coding standard, has twice of the compression efficiency compared to AVC/H.264 under the same image quality condition. To obtain the improved efficiency, however, it was adopted for many methods which need complicated calculation, and the time complexity of HEVC was increased more than that of AVC/H.264. To solve this problem, the various fast algorithms have been researched. In this paper, we propose a fast intra prediction mode decision method which uses result of Rough Mode Decision (RMD) and Most Probable Mode (MPM). The proposed method selects a best predicted mode by comparing each predicted directions which are calculated through RMD and MPM. We applied the proposed method to HM 10.0 and conducted an comparing experiment in All-Intra environment. The experiment result showed that total encoding time is reduced by about 26% on average with about a 0.8% loss of BD-rate.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2021.06a
• /
• pp.359-360
• /
• 2021

본 논문에서는 차세대 비디오 부호화 기술인 VVC (Versatile Video Coding)의 색차 성분 화면 내 예측 기술인 DM (Derived Mode) 가 분할 구조가 이중 트리일 때 색차 블록에 대응하는 휘도 블록을 선택하는 기존 방식의 효율성을 분석하기 위해 색차 블록에 대응하는 휘도 영역 내 휘도 블록의 개수를 측정하였다. 실험 결과, 하나의 색차 블록에 대응하는 휘도 영역 내에 평균적으로 4.408 개의 휘도 블록이 존재함을 확인하였다. 따라서 DM 을 통한 부호화 시 대응하는 휘도 영역 내 복수개의 휘도 블록을 고려하여, 유도되는 최적의 예측 모드를 잘 선정하는 방법에 대한 연구가 필요하다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2016.10a
• /
• pp.145-148
• /
• 2016

In this paper, we propose a design of Intra Prediction angular mode decision for high-performance HEVC encoder. Intra Prediction works by performing all 35 modes for efficient encoding. However, in order to process all of the 35 modes, the computational complexity and operational time required are high. Therefore, this paper proposes comparing the difference in the value of the original image pixel, using an algorithm that determines Angular mode efficiently. This new algorithm reduces the Hardware size. The hardware which is proposed was designed using Verilog HDL and was implemented in 65nm technology. Its gate count is 14.9k and operating speed is 2GHz.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.37 no.3
• /
• pp.163-171
• /
• 2024

Structural health monitoring for ships and offshore structures is important in various aspects. Ships and offshore structures are continuously exposed to various environmental conditions, such as waves, wind, and currents. In the event of an accident, immense economic losses, environmental pollution, and safety problems can occur, so it is necessary to detect structural damage or defects early. In this study, structural response data of multi-linked floating offshore structures under various wave load conditions was calculated by performing fluid-structure coupled analysis. Furthermore, the order reduction method with distortion base mode was applied to the structures for predicting the structural response by using the results of numerical analysis. The distortion base mode order reduction method can predict the structural response of a desired area with high accuracy, but prediction performance is affected by sensor arrangement. Optimization based on a genetic algorithm was performed to search for optimal sensor arrangement and improve the prediction performance of the distortion base mode-based reduced-order model. Consequently, a sensor arrangement that predicted the structural response with an error of about 84.0% less than the initial sensor arrangement was derived based on the root mean squared error, which is a prediction performance evaluation index. The computational cost was reduced by about 8 times compared to evaluating the prediction performance of reduced-order models for a total of 43,758 sensor arrangement combinations. and the expected performance was overturned to approximately 84.0% based on sensor placement, including the largest square root error.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.12
• /
• pp.652-658
• /
• 2016

In this paper, the theoretical research and simulation using the Finite Element Method (FEM) to design and form a micro-pattern for an ultrasonic horn is described. The present method is based on an initial design estimate obtained by FEM analysis. The natural and resonant frequencies required for the ultrasonic tool horn used for forming the fine pattern were predicted by finite element analysis. FEM analysis using ANSYS S/W was used to predict the resonant frequency for the optimum technical design of the ultrasonic horn vibration mode shape. When electrical power is supplied to the ultrasonic transducer, it is converted into mechanical movement energy, leading to vibration. The RFID TAG becomes the pattern formed on the insulating sheet by using the longitudinal vibration energy of the ultrasonic tool horn. The FEM analysis result is then incorporated into the optimal design and manufacturing of the ultrasonic tool horn.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2009.11a
• /
• pp.255-258
• /
• 2009

제한된 채널을 통하여 영상을 전송하고자 할 때 한정된 비트량 에서 최적의 화질을 얻기 위한 비트 할당기법은 영상의 부호화 과정에서 중요한 역할을 하며 중요한 연구 과제이다. H.264/AVC 표준안의 비트율 제어 방식은 영상의 복잡도에 따라 최적의 비트를 할당하는 방식을 사용하지만 첫 번째 프레임인 인트라 프레임에 대한 QP 값을 정확히 예측하지 못하는 문제점을 보인다. 비트율 제어에 있어 인트라 프레임의 복잡도를 예측하여 인트라 프레임에 대하여 할당되는 비트량은 인트라 프레임 이후 영상들의 화질에 큰 영향을 미치게 되므로 인트라 프레임의 복잡도를 예측하여 적절한 QP를 결정 하는 것은 매우 중요하다. 본 논문에서는 실시간 H.264/AVC를 위하여 인트라 모드의 적응적 비트율 제어 기법에 대해 제안한다. 통계적 실험을 통한 인트라 프레임과 인터 프레임과의 선형적 특성을 이용하여 인트라 프레임과 인터 프레임 간의 관계식을 도출한다. 이 관계식을 통하여 인터 프레임 이후에 일어나는 인트라 프레임의 QP 값을 정확하게 예측하는 비트율 제어 알고리즘을 제안한다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.9
• /
• pp.1957-1964
• /
• 2010

In Video coding, the first frame is encoded in intra mode which generates a larger number of bits. In addition, the first frame is used for the inter mode encoding of the following frames. Thus the intial QP for the first frame of GOP affects the first frame as well as the following frames. Traditionally, the initial QP of a GOP is determined by the initial QP of the previous GOP and the average QP of the inter mode frames. In case of JM, the initial QP of a GOP is adjusted as the initial QP being less than the average QP of inter mode frames by two. However, this method is not suitable for the low bit rate video coding. In this paper, the linear relationship between the optimal QP and the ratio of the PSNR of the first frame and the average PSNR of the inter mode frames is first investigated and the linear model is proposed based on the results of the investigation. The proposed model calculate the optimal initial QP using the encoding results of the previous GOP. It is shown by experimental results that the new algorithm can predict the optimal initial QP more accurately and generate the PSNR performance better than that of the existing JM algorithm.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.3
• /
• pp.129-138
• /
• 2014

This paper proposes a fast intra prediction method to reduce encoding time for the HEVC(high-efficiency video coding) encoder. The proposed fast Intra prediction method uses quadtree structure and SATD(Sum of Absolute Transformed Differences). In HEVC, a $8{\times}8$ SATD value using $8{\times}8$ hadamard transform is used to calculate a SATD value for $8{\times}8$ or larger blocks. The proposed method calculates the best SATD value by using each $8{\times}8$ SATD result in $16{\times}16$ or larger blocks. After that, the proposed method removes a candidate mode for RDO(Rate-Distortion Optimization) based on comparing SATD of the candidate mode and the best SATD. By removing candidate modes, the proposed method reduces the operation of RDO and reduces total encoding time. In $8{\times}8$ block, the proposed method uses additional $4{\times}4$ SATD to calculat the best SATD. The experimental results show that the proposed method achieved 5.08% reduction in encoding time compared to the HEVC test model 12.1 encoder with almost no loss in compression performance.

• Journal of Broadcast Engineering
• /
• v.19 no.5
• /
• pp.627-630
• /
• 2014

The latest video coding standard, high efficiency video coding (HEVC) achieves high coding efficiency by employing a quadtree-based coding unit (CU) block partitioning structure which allows recursive splitting into four equally sized blocks. At each depth level, each CU is partitioned into variable sized blocks of prediction units (PUs). However, the determination of the best CU partition for each coding tree unit (CTU) and the best PU mode for each CU causes a dramatic increase in computational complexity. To reduce such computational complexity, we propose a fast PU decision algorithm that early terminates PU search. The proposed method skips the computation of R-D cost for certain PU modes in the current CU based on the best mode and the rate-distortion (RD) cost of the upper depth CU. Experimental results show that the proposed method reduces the computational complexity of HM12.0 to 18.1% with only 0.2% increases in BD-rate.