• 한국광학회지
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• 제11권1호
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• pp.47-57
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• 2000

프란운호퍼 회절에 의하여 임의의 주어진 세기무늬를 발생시키는 연속적인 또는 양자화된 위상형 회절무늬소자를 설계하는데 hybrid input-output 알고리즘과 새로운 Pnoise 알고리즘을 결합.변형한 2단계 iterative Fourier transform 알고리즘을 이용하였다. 두 가지의 $128\times128$ 이진 세기 무늬와 두 가지의 grayscale 세기 무늬에 때하여 기존 알고리즘들과 비교하였는데, 2단계 iterative Fourier transform 알고리즘은 회절효율이 약간 낮지만 신호 대 잡음비와 특히 균일도에 있어서 우수한 결과를 보였다. 알고리즘에서 사용하는 매개변수들과 잡음영역의 크기에 따른 성능의 변화를 살펴보았고, 양자화된 위상소자의 경우 위상층수에 따른 변화도 살펴보았다. 양자화된 위상소자의 경우 세기 무늬보다는 잡음영역의 크기가 성능을 좌우하는 것으로 나타났다.

• 한국CDE학회논문집
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• 제14권2호
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• pp.129-136
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• 2009

Generally, curved surfaces of ship hull are deformed by flame bending (line heating), multi-press forming, and die-less forming method. The forming methods generate the required in-plane/bending strain or displacement on the flat plate to make the curved surface. Multi-press forming imposes the forced displacements on the flat plate by controlling the position of each pressing points based upon the shape difference between the unfolded flat plate and the curved object shape. The flat plate has been obtained from the unfolding system that is independent of the ship CAD. Apparently, the curved surface and the unfolded-flat surface are expressed by different coordinate systems. Therefore, one of the issues is to find a registration of the unfolded surface and the curved shape for the purpose of minimum amount of forming works by comparing the two surfaces. This paper presents an efficient algorithm to get an optimized registration of two different surfaces in the multi-press forming of ship hull plate forming. The algorithm is based upon the ICP (Iterative Closest Point) algorithm. The algorithm consists of two iterative procedures including a transformation matrix and the closest points to minimize the distance between the unfolded surface and curved surfaces. Thereby the algorithm allows the minimized forming works in ship-hull forming.

• 대한전자공학회논문지SD
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• 제40권5호
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• pp.298-311
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• 2003

Iterative Fourier transform algorithm (IFTA)은 회절광학소자 (DOE)의 위상 분포를 구하기 위한 반복적 수치 해석 알고리즘으로서 회절광학소자의 위상 분포는 반복 과정을 통하여 국소 최적해로 수렴하게 된다. Ink의 수렴은 위상 분포 초기치, 관측면에서의 자유도의 허용 범위 및 알고리즘에 내재된 매개 변수들의 설정 값에 영향을 받는다. 본 논문에서는 IFTA의 내부적 매개 변수인 완화 변수(relaxation parameter)가 IFTA의 수렴에 미치는 영향을 분석하고 이를 토대로 보다 정확한 최적화 해를 얻기 위한 유전 알고리즘과 IFTA의 하이브리드 알고리즘을 제안한다.

• Journal of Information Processing Systems
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• 제16권1호
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• pp.30-41
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• 2020

Lines and textures are natural properties of the surface of natural objects, and their images can be sparsely represented in suitable frames such as wavelets, curvelets and wave atoms. Based on characteristics that the curvelets framework is good at expressing the line feature and wavesat is good at representing texture features, we propose a model for the weighted sparsity constraints of the two frames. Furtherly, a multi-step iterative fast algorithm for solving the model is also proposed based on the split Bergman method. By introducing auxiliary variables and the Bergman distance, the original problem is transformed into an iterative solution of two simple sub-problems, which greatly reduces the computational complexity. Experiments using standard images show that the split-based Bergman iterative algorithm in hybrid domain defeats the traditional Wavelets framework or curvelets framework both in terms of timeliness and recovery accuracy, which demonstrates the validity of the model and algorithm in this paper.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집C
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• pp.408-413
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• 2001

The structural optimization is carried out in the continuous design space or discrete design space. Methods for discrete variables such as genetic algorithms are extremely expensive in computational cost. In this research, an iterative optimization algorithm using orthogonal arrays is developed for design in discrete space. An orthogonal array is selected on a discrete design space and levels are selected from candidate values. Matrix experiments with the orthogonal array are conducted. New results of matrix experiments are obtained with penalty functions for constraints. A new design is determined from analysis of means(ANOM). An orthogonal array is defined around the new values and matrix experiments are conducted. The final optimum design is found from iterative process. The suggested algorithm has been applied to various problems such as truss and frame type structures. The results are compared with those from a genetic algorithm and discussed.

• 한국통신학회논문지
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• 제27권6A호
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• pp.524-532
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• 2002

이 논문은, 램버트 W 함수가 라플라스 신호원에 대한 최적 (최소평균제곱오차) 양자기의 비반복적 설계에 이용될 수 있다는 사실을 보고한다. 구체적으로, 라플라스 신호원에 최적인 양자기의 비반복적 설계법을 고찰하며, 설계에 필수적인 비선형 방정식의 점화식의 풀이가 램버트 W 함수를 사용한 닫힌 식으로 표현된다는 것을 발견하였고, 또 이 논문에서는 이 설계법이 지수함수 형태나 라플라스 확률밀도함수 형태를 갖는 신호원에만 적용된다는 것을 증명하였다. 이 논문의 기여점은, 양자기의 설계가 비반복적이며, 원하는 만큼의 정확도로 설계되기 때문에 설계에 필요한 계산 회수가 감소되고, 양자점과 경계값을 구하는데 있어 높은 정확도를 갖는다는 점이다. 또한, 수치결과를 통하여 최적 양자 왜곡이 팬터-다잇 상수에 단조 증기적으로 수렴하는 과정을 관찰하였으며, 최적 양자기의 최외곽 경계값인 중요변수의 근사식을 유도하였다.

• 한국자동차공학회논문집
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• 제3권2호
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• pp.62-76
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• 1995

The safety analysis becomes very essential in the crash environment with the growth of automobile industry. Recently, an airbag system is required to protect the occupant. The effects of an airbag can be evaluated exactly from the barrier or sled test which is quite expensive. The airbag system in a passenger car is analyzed with the occupant analysis program. The modeling of the passenger car including an airbag is established and the results are verified by comparisons with real crash tests. However, the solution of an airbag design can not be obtained easily with the conventional method such as an optimization due to the nonlinearity and complexity of the problem. An iterative design algorithm using the orthogonal array is proposed to overcome the difficulties. The design trend of an airbag is recommended to minimize the injury of an occupant with the proposed design algorithm and the results are discussed.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.584-587
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• 2003

Iterative learning control is an approach to improve the transient response of systems that operate repetitively over a fixed time interval. It is useful for the system where the system output follows the different type input, in case of design or modeling uncertainty In this paper, we introduce the concept of iterative learning control and then apply the learning control algorithm for multi-motor system for performance Improvement.

• Journal of Communications and Networks
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• 제17권4호
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• pp.339-345
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• 2015

In this paper, we present an iterative reliability-based modified majority-logic decoding algorithm for two classes of structured low-density parity-check codes. Different from the conventional modified one-step majority-logic decoding algorithms, we design a turbo-like iterative strategy to recover the performance degradation caused by the simply flipping operation. The main computational loads of the presented algorithm include only binary logic and integer operations, resulting in low decoding complexity. Furthermore, by introducing the iterative set, a very small proportion (less than 6%) of variable nodes are involved in the reliability updating process, which can further reduce the computational complexity. Simulation results show that, combined with the factor correction technique and a well-designed non-uniform quantization scheme, the presented algorithm can achieve a significant performance improvement and a fast decoding speed, even with very small quantization levels (3-4 bits resolution). The presented algorithm provides a candidate for trade-offs between performance and complexity.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 통신소사이어티 추계학술대회논문집
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• pp.28-31
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• 2003

In this paper, it proposes the efficient iterative decoding stop criterion using the variance value of LLR. It is verifying that the proposal iterative de-coding stop criterion can be reduced the average iterative decoding number. The proposal algorithm md hardware synthesize to use the Synopsys Tool, performance validations perform through the ModelSim.