• Geophysics and Geophysical Exploration
• /
• v.15 no.2
• /
• pp.57-65
• /
• 2012

Various numerical methods in simulation of seismic wave propagation have been developed. Recently an innovative numerical method called as the Spectral Element Method (SEM) has been developed and used in wave propagation in 3-D elastic media. The SEM that easily implements the free surface of topography combines the flexibility of a finite element method with the accuracy of a spectral method. It is generally used a weak formulation of the equation of motion which are solved on a mesh of hexahedral elements based on the Gauss-Lobatto-Legendre integration rule. Variational formulations of velocity-stress motion are newly modified in order to implement ADE-PML (Auxiliary Differential Equation of Perfectly Matched Layer) in wave propagation in 3-D elastic media, because a general weak formulation has a difficulty in adapting CFS (Complex Frequency Shifted) PML (Perfectly Matched Layer). SEM of Velocity-Stress motion having ADE-PML that is very efficient in absorbing waves reflected from finite boundary is verified with simulation of 1-D and 3-D wave propagation.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.11
• /
• pp.188-194
• /
• 2013

In this paper, we proposed a new method for pulmonary vessels image segmentation and refinement from pulmonary image. Proposed method consist of following five steps. First, threshold estimation is performed by polynomial regression analysis of histogram variation rate of the pulmonary image. Second, segmentation of pulmonary vessels object is performed by density-based segmentation method based on estimated threshold in first step. Third, 2D connected component labeling method is applied to segmented pulmonary vessels. The seed point of both side diaphragms is determined by eccentricity and size of component. Fourth step is diaphragm extraction by 3D region growing method at the determined seed point. Finally, noise cancelation of pulmonary vessels image is performed by 3D connected component labeling method. The experimental result is showed accurately pulmonary vessels image segmentation, the diaphragm extraction and the noise cancelation of the pulmonary vessels image.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.6 no.2
• /
• pp.160-168
• /
• 1982

수평으로 놓여진 2개의 동심타원 사이의 환상공간에서의 자연대류현상이 수치계산 및 실험적으로 연구되었다. 수치적 연구는 정상 2차원 층류유동영역에서 수행되었으며 유선 및 등온선이 구하여 졌다. 또한 특수한 경우로서 수평동심원 사이의 환상공간에 관한 기존연구와 비교하여 좋은 일치 를 보았다. 실험적 연구에서는 3개의 실험모델을 제작하였으며 마하젠더 간섭계에 의한 간섭사진 으로부터 등온선 분포를 얻었으며 아울러 유동에 관한 정보도 얻을 수 있었다. 실험과 수치계산 결과는 상당히 좋은 일치를 보였으며 기존 동심원환상공간에 편심율이 추가된 이론전개 및 수치 계산방법의 적합성을 알 수 있었고 이로서 환상공간에서의 자연대류에 관한 연구를 확장시켰다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.18 no.12
• /
• pp.1970-1982
• /
• 1993

This paper describes an efficient array algorithm for parallel computation of vector-radix two-dimensional (2-D) fast discrete cosine transform (VR-FCT), and its VLSI implementation. By mapping the 2-D VR-FCT onto a 2-D array of processing elements (PEs), the butterfly structure of the VR-FCT can be efficiently importanted with high concurrency and local communication geometry. The proposed array algorithm features architectural modularity, regularity and locality, so that it is very suitable for VLSI realization. Also, no transposition memory is required, which is invitable in the conventional row-column decomposition approach. It has the time complexity of O(N+Nnzp-log2N) for (N*N) 2-D DCT, where Nnzd is the number of non-zero digits in canonic-signed digit(CSD) code, By adopting the CSD arithmetic in circuit desine, the number of addition is reduced by about 30%, as compared to the 2`s complement arithmetic. The computational accuracy analysis for finite wordlength processing is presented. From simulation result, it is estimated that (8*8) 2-D DCT (with Nnzp=4) can be computed in about 0.88 sec at 50 MHz clock frequency, resulting in the throughput rate of about 72 Mega pixels per second.

• Journal of Korea Society of Industrial Information Systems
• /
• v.6 no.2
• /
• pp.16-22
• /
• 2001

In this paper we mose a new scheme for recognition of deformed letters by extracting feature vectors based on Gibbs distributions which are well suited for representing the spatial continuity. The extracted feature vectors are comprised of 2-D conditional moments which are invariant under translation, rotation, and scale of an image. The Algorithm for pattern recognition of deformed letters contains two parts: the extraction of feature vector and the recognition process. (i) We extract feature vector which consists of an improved 2-D conditional moments on the basis of estimated conditional Gibbs distribution for an image. (ii) In the recognition phase, the minimization of the discrimination cost function for a deformed letters determines the corresponding template pattern. In order to evaluate the performance of the proposed scheme, recognition experiments with a generated document was conducted. on Workstation. Experiment results reveal that the proposed scheme has high recognition rate over 96%.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2020.11a
• /
• pp.160-161
• /
• 2020

본 논문에서는 비디오 코딩 잔차신호를 보다 효율적으로 변환하기 위하여 오프라인으로 잔차신호를 학습하여 RD(Rate Distortion) Cost를 기반으로 분류된 몇 가지 변환 기저들을 생성하고, 비디오 복호화 과정 중 잔차신호를 역변환을 수행할 때 주변의 복호화가 완료된 신호들을 이용하여 최적의 변환 기저를 선택하여 해당 변환 기저로 역변환을 수행하여 효율적으로 잔차신호를 압축하는 방법에 대해 제안한다. 변환 기저 생성에는 분류된 잔차신호들에 대하여 2 차원 혹은 1 차원 KLT를 계산함으로써 얻어내어진다. 제안하는 방법은 VTM(VVC Test Model) version 10에서 실험하였으며 약 0.5% 정도의 성능향상을 보인다.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.39 no.3
• /
• pp.73-84
• /
• 2002

Fast and accurate new capacitance determination methodology for non-uniform complicated multi-layer VLSI interconnects is presented. Since a capacitance determination of intricate multi-layer interconnects using 3-dimensional field-solver is not practical, quasi-3-dimensional methodology is presented. Interconnects with discontinuity (i.e., bend structure and different spacing between lines, etc.) are partitioned. Then, each partial capacitance of divided parts is extracted by using 2-dimensional extraction methodology. For a multi-layer interconnects with shielding layer, the system can be simplified by investigating a distribution of charge in it. Thereby, quasi-3-dimensional capacitance for multi-layer interconnects can be determined by combining solid-ground based 2-dimensional capacitance and shielding effect which is independently determined with layout dimensions. This methodology for complicated multi-layer interconnects is more accurate and cost-efficient than conventional 3-dimensional methodology It is shown that the quasi-3-dimensional capacitance methodology has excellent agreement with 3-dimensional field- solver-based results within 5% error.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2001.10a
• /
• pp.180-184
• /
• 2001

본 연구에서는 반잠수식 Rig의 형상에 따른 최적 형상을 검토하기 위하여 최근 건조되고 있는 4-Column과 2-Lowhull 을 가진 원통형 Column과 4각 Column형을 공시모형으로 택하여 규칙파중 두 구조물에 작용하는 유체력과 유체력에 의한 운동 응답을 계산, 형상에 따른 유체 역학적 특성과 동요 진폭의 관계를 검토하였다. 수치계산은 3차원 특이점 분포법을 이용하여 정상상태에 대하여 실행하였다. 구조물의 형상과 역학적인 간섭의 영향을 이용, 보다 성능이 우수한 형상을 얻을 수 있음을 확인하였다.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
• /
• 1995.10a
• /
• pp.85-90
• /
• 1995

수조에서 조파기로 규칙파와 불규픽파를 발생하는 실험은 오래전부터 수행되었고, 최근에는 이를 수치계산으로 검증하려는 노력이 이루어지고 있다. 본 논문에서는 2차원 수조에서 조파판의 작동을 적절히 조절하여 임의의 지점에 plunger 형 쇄파를 발생시키고, 수치계산으로 이를 확인한 내용을 담았다. 쇄파를 만드는 연구는 Chan(1988)이 조화함수를 합성시키는 기법으로 실험을 수행한 바가 있고, Dommermuth 등(1988)이 이를 수치적으로 검증하였다. (중략)

• Proceedings of the Korean Vacuum Society Conference
• /
• 1993.02a
• /
• pp.38-40
• /
• 1993

급속 열처리 시스템내에서의 비정상상태 온도분포, 가스유동형태, 웨이퍼내 열응력등을 여러 가지 작동조건하에서 2차원 유한 차분법으로 계산하였다. 계산결과는 실험에서 얻은 에피성장률 데이터와 비교 검증하였다. RTpp내 가스 유동이나 온도분포는 압력 및 주위 구성요소에 크게 의존하는 반면, 웨이퍼의 온도분포는 wafer edge loss가 큰 고온에서 온도 불균일도가 가장 크다. 저온에서는 대류에 의한 열 손실이 웨이퍼내의 온도 불균일도에 큰 영향을 미치고 있다. 웨이퍼상의 열응력을 가장 크게 받는 시점은 transient condition에서 나타났다.