• Journal of Digital Contents Society
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• v.8 no.4
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• pp.441-449
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• 2007

In video coding, motion estimation is a process to estimate the pixel of the current frame from the reference frame, which affects directly the predictive quality and the encoding time. This paper is related to AHHS(Adaptive Hierarchical Hexagon Search) using spatio-temporal motion activity for fast motion estimation. The proposed method defines the spatio-temporal motion activity of the current macroblock using the motion vectors of its spatio-temporally adjacent macroblocks, and then conventional AHS(Adaptive Hexagon Search) is performed if the spatio-temporal motion activity is lower, otherwise, hierarchical hexagon search is performed on a multi-layered hierarchical space constructed by multiple sub-images with low frequency in wavelet transform. In the paper, based on computer simulation results for multiple video sequences with different motion characteristics, the performance of the proposed method was analysed and assessed in terms of the predictive quality and the computational time. Experimental results indicate that the proposed method is both suitable for (quasi-) stationary and large motion searches. The proposed method could keep the merit of the adaptive hexagon search capable of fast estimating motion vectors and also adaptively reduce the local minima occurred in the video sequences with higher spatio-temporal motion activity.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1932-1935
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• 2003

본 논문에서는 MPEG-2, MPEG-4, H.263 등에서 블록정합을 위해 사용되는 움직임 추정(Motion Estimation) 기법에서 적응적 탐색 범위를 기존의 알고리듬에 적용시킴으로써 계산량을 줄이고 화질도 개선하는 방법을 제안한다 제안된 알고리듬은 먼저 이웃한 움직임 벡터(Motion Vector)의 위치를 이용하여 예상된 움직임 벡터를 찾고 이 예상된 움직임 벡터의 X, Y 값의 크기를 작은 값, 중간 값, 큰 값, 세 가지로 분류해서 탐색범위를 적응적으로 변화시켜 움직임 벡터가 있을 확률이 큰 범위를 집중적으로 찾는다 그리고 각 분류에서 작은 값일 때는 전역 탐색을 적용하고 큰 값일 때는 기존의 알고리듬을 적용시키고 중간 값 일 때는 3단계탐색 기법을 적용시켜 더 적합한 움직임 벡터를 찾도록 하였다. 그리고 작은 값 일 때 구해진 움직임 벡터의 SAD(Sum of Absolute Difference) 값과 이웃한 움직임 벡터의 SAD값을 비교해 국소점에 빠졌다고 판단이 되면 다시 탐색 범위를 조정해서 움직임 벡터를 구함으로써 국소점에 빠지는 경우를 줄였다.

• Journal of the Korean Institute of Intelligent Systems
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• v.27 no.1
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• pp.79-87
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• 2017

The microphysical processes of the numerical weather prediction (NWP) model cover the following : fall speed, accretion, autoconversion, droplet size distribution, etc. However, the microphysical processes and parameters have a significant degree of uncertainty. Parameter estimation was generally used to reduce errors in NWP models associated with uncertainty. In this study, the micro- genetic algorithm and harmony search algorithm were used as an optimization algorithm for estimating parameters. And we estimate parameters of microphysics for the Unified model in the case of precipitation in Korea. The differences which occurred during the optimization process were due to different characteristics of the two algorithms. The micro-genetic algorithm converged to about 1.033 after 440 times. The harmony search algorithm converged to about 1.031 after 60 times. It shows that the harmony search algorithm estimated optimal parameters more quickly than the micro-genetic algorithm. Therefore, if you need to search for the optimal parameter within a faster time in the NWP model optimization problem with large calculation cost, the harmony search algorithm is more suitable.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1928-1931
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• 2003

본 논문은 가장 최근의 동영상 국제표준인 H.264 비디오 코덱을 사용하여 QCIF 영상을 초당 10 프레임 정도의 속도로 실시간 부호화하는 것을 목적으로, 부호화 시 필요한 연산의 약 80％-90％를 차지하는 움직임 추정을 고속으로 처리할 수 있는 알고리즘을 개발하는 것을 내용으로 하고 있다. 제안하는 고속 움직임 추정 알고리즘은 MPEG겨 등의 고속 움직임 추정에 사용되었던 기존의 알고리즘을 다중 프레임 레퍼런스 등 새로운 특징을 갖는 H.264 코덱에 적합한 형태로 개선하고, 움직임 추정의 정밀도가 1/4 화소 단위로 향상됨으로써 늘어난 부화소단위 움직임 추정의 상대적 부담을 함께 고려하면서, 모드 선택과정과 효과적으로 결합함으로써 보다 향상된 성능을 나타내고 있다. 모의실험 결과, 기존의 공식 JVT-AVC 레퍼런스 소프트웨어인 JM (Joint Model) 에 구현되어 있는 고속 움직임 추정 알고리즘에 비해서 최대 80％, 평균적으로 60％의 속도개선 효과가 있음이 입증되어, 최근 JM 의 새로운 고속 움직임 추정 알고리즘으로 채택된 JVT-F0l7 알고리즘에 본 논문에서 제안하는 레퍼런스 프레임 탐색 제한 알고리즘을 결합시킴으로써 추가적으로 약 45％의 속도 개선을 얻을 수 있음을 확인하였다.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.9
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• pp.85-91
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• 2013

This paper proposes the data reusable search scan methods for full search and fast search to implement low power Motion Estimation (ME). The proposed Optimized Sub-region Partitioning (OSP) method which divide search region into several sub-region can reduce the number of the required Reconfigurable Register Array (RRA) by half compared to the existing smart snake scan method for the same data reusability. In addition, the proposed Center Biased Search Scan method (CBSS) for various fast search algorithms can improve the data reusability. The performance comparisons show that the proposed search scan methods can reduce the average redundant data loading about 26.9% and 16.1% compared with the existing rater scan and snake scan methods, respectively. Due to the reduction of memory accesses, the proposed search scan methods are quite suitable for low power and high performance ME implementation.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.37 no.5
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• pp.54-63
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• 2000

We present a multi-resolution block matching algorithm (BMA) for fast motion estimation At the coarsest level, a motion vector (MV) having minimum matching error is chosen via a full search, and a MV with minimum matching error is concurrently found among the MVs of the spatially adjacent blocks Here, to examine the spatial MVs accurately, we propose an efficient method for searching full resolution MV s without MV quantization even at the coarsest level The chosen two MV s are used as the initial search centers at the middle level At the middle level, the local search is performed within much smaller search area around each search center If the method used at the coarsest level is adopted here, the local searches can be done at integer-pel accuracy A MV having minimum matching error is selected within the local search areas, and then the final level search is performed around this initial search center Since the local searches are performed at integer-pel accuracy at the middle level, the local search at the finest level does not take an effect on the overall performance So we can skip the final level search without performance degradation, thereby the search speed increases Simulation results show that in comparison with full search BMA, the proposed BMA without the final level search achieves a speed-up factor over 200 with minor PSNR degradation of 02dB at most, under a normal MPEG2 coding environment Furthermore, our scheme IS also suitable for hardware implementation due to regular data-flow.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.1
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• pp.64-70
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• 2011

In an H.264/AVC video encoder, the motion estimation at fractional pixel accuracy improves a coding efficiency and image quality. However, it requires additional computation overheads for fractional search and interpolation, and thus, reducing the computation complexity of fractional search becomes more important. This paper proposes a Pixel Re-composition Fractional Motion Estimation (PRFME) algorithm for an H.264/AVC video encoder. Fractional Motion Estimation performs interpolation for the overlapped pixels which increases the computational complexity. PRFME can reduce the computational complexity by eliminating the overlapped pixel interpolation. Compared with the fast full search, the proposed algorithm can reduce 18.1% of computational complexity, meanwhile, the maximum PSNR degradation is less than 0.067dB. Therefore, the proposed PRFME algorithm is quite suitable for mobile applications requiring low power and complexity.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.07a
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• pp.121-123
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• 2012

본 논문에서는 2D-to-3D 변환을 위한 기하구조 기반 깊이 추정에 적합한 소실점 검출 기법을 제안한다. 3D 공간에서 평행한 직선들은 2D 공간으로의 투시영상에서 시점에서 멀어질수록 간격이 좁아지고, 결국에는 한 점으로 수렴하게 된다. 수렴된 점을 소실점(vanishing point)이라 하고, 소실점을 거쳐 지나는 직선들을 소실선(vanishing lines)이라고 한다. 일반적으로, 인간은 소실선과 소실점을 추정한 2D 영상에서 소실점이 관찰자 시점으로부터 제일 먼 지점이라는 인식을 이용하여 깊이 정보를 인지할 수 있다. 전경영역과 배경영역 간의 경계에서는 수직성분을 가진 선들이 생성되어 올바른 소실점을 검출하는데 방해가 될 수 있다. 그렇기 때문에 본 논문에서는 수직성분을 가진 선들을 제거하여 소실점을 탐색하는 기법을 제안한다.

• Journal of the Korean Data and Information Science Society
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• v.20 no.3
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• pp.485-492
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• 2009

In this paper, we studied process capability analysis for brake-pad manufacturing system and considered Weibull, normal and logistic distributions for density estimation of wear life of brake pads for a passenger car with a real data. These three distributions are seem to work well. Estimated percentiles of brake pads can be used to evaluate the design criteria and customers' need for brake pads.

• Journal of Satellite, Information and Communications
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• v.10 no.4
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• pp.146-150
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• 2015

The COSPAS-SARSAT committee decides MEOSAR (Medium-Earth Orbit for search and rescue) service development for installing 406MHz SAR instruments on their respective MEO navigation satellite system of the United States, EU, and Russia, since 2000. The transmitted beacon signal is separately arrived by satellites with different FOA (Frequency of Arrival) and TOA (Time of Arrival). It is directly transferred to MEOLUT. In MEOLUT, a LUT track at least 3 or 4 satellites simultaneously and estimate location of beacon using time difference of arrival (TDOA) and frequency difference arrival (FDOA). But the transmitted distress signals may be overlapped each other because the distress beacons transmit signal on mean interval of 50 seconds in arbitrary time. It's difficult that simultaneously estimate location of beacon by current scheme for several overlapped distress signal. So we use cross ambiguity function (CAF) Map algorithm and present Multi-CAF MAP scheme in order to satisfy performance requirement of system. The performance is analyzed for COSAPS-SARSAT MEOSAR.