• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2006년도 추계 학술대회논문집
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• pp.7-8
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• 2006

The governing equations for high-speed lateral atomizing injector nozzle flow based on the LES-VOF model in conjunction with the CSF model are presented, and then an integrated parallel computation are performed to clarify the detailed atomization process of a high speed nozzle flow and to acquire data which is difficult to confirm by experiment such as atomization length, liquid core shapes, droplets size distributions, spray angle and droplets velocity profiles. According to the present analysis, it is found that the atomization rate and the droplets-gas two-phase flow characteristics are controlled by the turbulence perturbation upstream of the injector nozzle, hydrodynamic instabilities at the gas-liquid interface, shear stresses between liquid core and periphery of the jet. Furthermore, stable and a high-resolution computation can be attained in the high density ratio (pl/ pg = 554) conditions conditions by using our numerical method.

• 전자공학회논문지A
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• 제32A권4호
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• pp.75-84
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• 1995

Fault simulators are used for accurate evaluation of fault coverages of digital circuits. But fault simulation becomes time and memory consuming job because computation time is proportional to wquare of size of circuits. Recently, several approximate algorithms for testability analysis have been published to cope with the problems. COP is very fast but cannot be used for sequential circuits, while STAFAN can ve used for sequential circuits but requires large amount of computation because it utilizes logic simulation results. In this paper EXTASEC(An Extension of Testability Analysis for Sequential Circuits) is proposed. It is an extension of COP in the sense that it is the same as COP for combinational circuits, but it can handle sequential circuits, Xicontrollability and backward line analysis are key concept for EXTASEC. Performance of EXTASEC is proven by comparing EXTASEC with a falut simulator, STAFAN, and COP for ISCAS circuits, and the result is demonstated.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.474-478
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• 1999

Genetic algorithm is an efficient search method using principles of natural selection and population genetics. In conventional genetic algorithms, however, the size of gene pool should be increased to insure a convergency. Therefore, many memory spaces and much computation time were needed. Also, since child chromosomes were generated by chromosome crossover and gene mutation, the algorithms have a complex structure. Thus, in this paper, a compact stereo matching algorithm using a population-based incremental teaming based on probability vector is proposed to reduce these problems. The PBIL method is modified for matching environment. Since the Proposed algorithm uses a probability vector and eliminates gene pool, chromosome crossover, and gene mutation, the matching algorithm is simple and the computation load is considerably reduced. Even if the characteristics of images are changed, stable outputs are obtained without the modification of the matching algorithm.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권3호
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• pp.325-330
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• 2014

Eddy current induction is used in a wide range of electronic devices, for example in detection sensors. Due to the advances in computer hardware and software, the need for 3D computation and system comprehension is a requirement to develop and optimize such devices nowadays. Pure theoretical models are mostly limited to special cases. On the other hand, the classical use of commercial Finite Element (FE) electromagnetic 3D models is not computationally efficient and lacks modeling flexibility or robustness. The proposed approach focuses on: (1) implementing theoretical formulations in 3D (FE) model of a detection device as well as (2) an automatic Volumetric Estimation Method (VEM) developed to selectively model the target finite elements. Due to these two approaches, this model is suitable for parametric studies and optimization of the number, location, shape, and size of PCB receivers in order to get the desired target discrimination information preserving high accuracy with tenfold reduction in computation time compared to commercial FE software.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권6호
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• pp.771-780
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• 2016

Detecting a set of longest paths is one of the crucial steps in static timing analysis and optimization. Recently, the process variation during manufacturing affects performance of the circuit design due to nanometer feature size. Measuring the performance of a circuit prior to its fabrication requires a considerable amount of computation time because it requires multi-corner and multi-mode analysis with process variations. An efficient algorithm of detecting the K-most critical paths in multi-corner multi-mode static timing analysis (MCMM STA) is proposed in this paper. The ISCAS'85 benchmark suite using a 32 nm technology is applied to verify the proposed method. The proposed K-most critical paths detection method reduces about 25% of computation time on average.

• 대한산업공학회지
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• 제11권2호
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• pp.57-73
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• 1985

Group scheduling problem in a multi-stage manufacturing system is reviewed and two heuristic procedures for minimizing the makespan are developed by employing the methods of flow shop sequencing heuristics with a slight modification. The comparisons among the five heuristics, three previously reported heuristics and two heuristics suggested by this study, are made on different problem sizes. The computational results indicate that NEH-GS method gives better group schedules than the other heuristics tested, but its computation time increases rapidly as the problem size increases. On the other hand, CDS-GS method provides relatively good group schedules with less computation time compared with NEH-GS method.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1998년도 Proceedings of International Symposium on Remote Sensing
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• pp.180-185
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• 1998

Microwave polarimetric backscattering from a various types of grassland canopies has been analyzed by using the first-order radiative transfer theory in this paper. Leaves in the grassland are modeled by rectangular resistive sheets, which sizes (widths and lengths) and orientations (elevation and azimuth angles) are randomly distributed. Surface roughness and soil moisture of the ground plane under the grass canopy is considered in this computation. The backscattering coefficients of grasslands are computed for different radar parameters (angles, frequencies and Polarizations) as well as different canopy Parameters (size and orientation distributions of leaves, canopy depth, moisture contents of leaves and soil, rms height and correlation length of soil surface). A radar system for 15GHz has been fabricated and used for measurement of the scattering coefficient from a grass canopy. The computation result obtained by the scattering model for the grass canopy is compared with the measurements.

• 인터넷정보학회논문지
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• 제7권1호
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• pp.49-57
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• 2006

본 논문에서는 128-bit 블록암호인 SEED 알고리즘을 하드웨어로 구현하는데 있어서 면적을 줄이고 연산속도를 증가시키는 회로구조에 대하여 논하였고 설계결과를 기술하였다. 연산속도를 증가시키기 위해 pipelined systolic array 구조를 사용하였으며, 입출력회로에 어떤 버퍼도 사용하지 않는 간단한 구조이다. 이 회로는 10 MHz 클럭을 사용하여 최대 320 Mbps의 암호화속도를 달성할 수 있다. 회로설계는 VHDL 코딩방식으로 수행하였으며, 50,000 gates 급의 FPGA에 구현하였다.

• 대한전기학회논문지:전력기술부문A
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• 제49권2호
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• pp.70-77
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• 2000

This paper proposes a method of solving a unit commitment problem using tabu search (TS) which is heuristic algorithm. Ts is a local search method that starts from any initial solution and attempts to determine a better solution using memory structures. In this paper, to reduce the computation time for finding the optimal solution, changing tabu list size as intensification strategy and path relinking method as diversification strategy are proposed. To show the usefulness of the proposed method, we simulated for 10 units system and 110 units system. Numerical results show improvements in the generation costs and the computation time compared with priority list, genetic algorithm(GA), and hybrid GA.

• 대한전기학회논문지
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• 제41권5호
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• pp.468-473
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• 1992

A boundary element analysis using parallel algorithm on transputers is described for three-dimensional magnetostatic field computations. The parallel algorithm are applied to assembling the system matrix and solving the matrix equation. Through the numerical results, it is shown that the computation time is ideally inverse proportional to the number of transputers, and the computational efficiency increases as the size of the system matrix becomes large. The easiness and simplicity in configuring the system hardware and making programs and computation times are compared in three kinds of topologies.