• 한국CDE학회논문집
• /
• 제11권2호
• /
• pp.97-106
• /
• 2006

Voronoi diagrams have been known for numerous important applications in science and engineering including CAD/CAM. Especially, the Voronoi diagram for 3D spheres has been known as very useful tool to analyze spatial structural properties of molecules or materials modeled by a set of spherical atoms. In this paper, we present two algorithms, the edge-tracing algorithm and the region-expansion algorithm, for constructing the Voronoi diagram of 3D spheres and applications to protein structure analysis. The basic scheme of the edge-tracing algorithm is to follow Voronoi edges until the construction is completed in O(mn) time in the worst-case, where m and n are the numbers of edges and spheres, respectively. On the other hand, the region-expansion algorithm constructs the desired Voronoi diagram by expanding Voronoi regions for one sphere after another via a series of topology operations, starting from the ordinary Voronoi diagram for the centers of spheres. It turns out that the region-expansion algorithm also has the worst-case time complexity of O(mn). The Voronoi diagram for 3D spheres can play key roles in various analyses of protein structures such as the pocket recognition, molecular surface construction, and protein-protein interaction interface construction.

• 융합신호처리학회논문지
• /
• 제7권4호
• /
• pp.155-160
• /
• 2006

본 논문에서는 웨이브릿 변환 영역의 4개의 서브밴드와 임계값 처리를 이용하는 계층적 블록 매칭 알고리즘을 제안하였다. 제안한 알고리즘은 다분해능의 첫 번째 레벨에서 웨이브릿 변환 영역의 4개 서브밴드를 이용함으로써 복원된 영상의 PSNR 성능을 향상시켰고, 움직임 벡터에 대한 임계값 처리를 하여 계산량을 줄였다. Carphone 영상과 Mother and Daughter 영상에 대한 실험에서 기존의 계층적 움직임 추정 알고리즘과 비교하여 임계값을 0으로 하였을 경우에 계산량은 최대 16%까지 증가하였으나 복원된 영상의 PSNR 성능은 최대 0.16dB 정도 향상된 결과를 보였고, 임계값을 증가시킴에 따라서 계산량은 최대 8%정도 줄고 복원된 영상의 PSNR은 비슷한 성능을 보였다.

• 한국통신학회논문지
• /
• 제15권3호
• /
• pp.221-231
• /
• 1990

본 논문에서는 예측오차의 분포와 비트할당표를 이용하여 계산량을 줄이는 방법으로 직접 2차원 WHT를 계산한 다음 상수행렬을 곱함으로써 2차원 DCT 를 계산하는 방법을 제안하였다. 이 2차원 고속 DCT 알고리즘은 곱셈이 마지막 단계에 집중되어 있으며, 따라서 변환계수 중에서 양자화 과정에서 제외되는 변환계수의 수에 비례하여 계산량을 줄일 수 있는 특징이 있다. 계산량 비교를 위하여, 예측오차에 대한 비교할당표에 할당된 DCT계수만을 구하고자 할 때의 계산량을 산출한 결과, 제안한 방식은 변환부호화에 할당된 화소당 평균 비트율이 0.6비트 이하일 때, 기존의 알고리즘 중에서 가장 계산량이 적은 고속 DCT 알고리즘 보다 계산량이 적게 되어, 변환부호화의 계산량 감축에 기여할 수 있음을 확인하였다.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2004년도 봄 학술발표회 논문집
• /
• pp.1-8
• /
• 2004

For the linearized differential algebraic equation of the nonlinear constrained system, exact initial values of the acceleration are needed to solve itself. It may be very troublesome to perform the inverse operation for obtaining the incremental quantities since the mass matrix contains the zero element in the diagonal. This fact makes the mass matrix impossible to be positive definite. To overcome this singularity phenomenon the mass matrix needs to be modified to allow the feasible application of predictor and corrector in the iterative computation. In this paper the proposed numerical algorithm based on the modified mass matrix combines the conventional implicit algorithm, Newton-Raphson method and Newmark method. The numerical example presents reliabilities for the proposed algorithm via comparisons of the 4th order Runge-kutta method. The proposed algorithm seems to be satisfactory even though the acceleration, Lagrange multiplier, and energy show unstable behaviour. Correspondingly, it provides one important clue to another algorithm for the enhancement of the numerical results.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2000년도 봄 학술발표회논문집
• /
• pp.458-465
• /
• 2000

In the field of structural optimization simulated annealing (SA) algorithm has widely been adopted as an optimizer with the positive features of SA such as simplicity of the algorithm and possibility of finding global solution However, annealing process of SA algorithm based on random generator with the zeroth order structural information requires a large of number of iterations highly depending on cooling schedules and stopping criteria. In this paper, MSA algorithm is presented in the form of two phase annealing process with the effective cooling schedule and stopping criteria. With the application to optimal seismic design of steel structures, the performance of the proposed MSA algorithm has been demonstrated with respect to stability and global convergence of the algorithm

• 한국CDE학회논문집
• /
• 제18권2호
• /
• pp.129-137
• /
• 2013

This paper proposed the scheduling method for tire mixing processes using the genetic algorithm. The characteristics of tire mixing process have the manufacturing routing, operation machine and operation time by compound types. Therefore, the production scheduling has to consider characteristics of the tire mixing process. For the reflection of the characteristics, we reviewed tire mixing processes. Also, this paper introduces the genetic algorithm using the crossover and elitist preserving selection strategy. Fitness is measured by the makespan. The proposed genetic algorithm has been implemented and tested with two examples. Experimental results showed that the proposed algorithm is superior to conventional heuristic algorithm.

• The Journal of the Acoustical Society of Korea
• /
• 제24권1E호
• /
• pp.34-37
• /
• 2005

Ryu et al. proposed a multiple target angle-tracking algorithm without a data association problem using angular innovations. This algorithm, however, needs the computational loads in proportion to the square number of sensors regardless of the number of targets, because it uses a nonlinear equation between the signal subspace and angular innovation. In this Paper, we proposed an efficient algorithm for the multiple target angle-tracking using angular innovations. The proposed algorithm extracts the angular innovations from noise subspace. Also, it is demonstrated by computer simulations dealing with the tracking of crossing targets. The simulation results show that the computational loads of the proposed algorithm are $80\%$ and $60\%$ of those of Ryu's algorithm for 3 targets and 6 targets without degrading the performance of the target tracking.

• 한국CDE학회논문집
• /
• 제4권3호
• /
• pp.190-199
• /
• 1999

Presented in this paper is an algorithm for finding all intersections among polygonal chains with an O((n+k)·log m) worst-case time complexity, where n is the number of lien segments in the polygonal chains, k is the number of intersections, and m is the number of monotone chains. The proposed algorithm is based on the sweep line algorithm. Unlike the previous polygonal-chain intersection algorithms that are designed to handle special only cases, such as convex polygons or C-oriented polygons, the proposed algorithm can handle arbitrarily shaped polygonal chains having self-intersections and singularities (tangential contact, multiple intersections). The algorithms has been implemented and applied to 1) testing simplicity of a polygon, 2) finding intersections among polygons and 3) offsetting planar point-sequence curves.

• ETRI Journal
• /
• 제29권4호
• /
• pp.445-451
• /
• 2007

An adaptive modulation scheme is presented for multiuser orthogonal frequency-division multiplexing systems. The aim of the scheme is to minimize the total transmit power with a constraint on the transmission rate for users, assuming knowledge of the instantaneous channel gains for all users using a combined bit-loading and subcarrier allocation algorithm. The subcarrier allocation algorithm identifies the appropriate assignment of subcarriers to the users, while the bit-loading algorithm determines the number of bits given to each subcarrier. The proposed bit-loading algorithm is derived from the geometric progression of the additional transmission power required by the subcarriers and the arithmetic-geometric means inequality. This algorithm has a simple procedure and low computational complexity. A heuristic approach is also used for the subcarrier allocation algorithm, providing a trade-off between complexity and performance. Numerical results demonstrate that the proposed algorithms provide comparable performance with existing algorithms with low computational cost.

• Steel and Composite Structures
• /
• 제16권6호
• /
• pp.681-701
• /
• 2014

The main aim of this study is to propose an efficient meta-heuristic algorithm for topology optimization of geometrically nonlinear single layer domes by serially integration of computational advantages of firefly algorithm (FA) and particle swarm optimization (PSO). During the optimization process, the optimum number of rings, the optimum height of crown and tubular section of the member groups are determined considering geometric nonlinear behaviour of the domes. In the proposed algorithm, termed as FA-PSO, in the first stage an optimization process is accomplished using FA to explore the design space then, in the second stage, a local search is performed using PSO around the best solution found by FA. The optimum designs obtained by the proposed algorithm are compared with those reported in the literature and it is demonstrated that the FA-PSO converges to better solutions spending less computational cost emphasizing on the efficiency of the proposed algorithm.