• 제목/요약/키워드: Computations

검색결과 1,823건 처리시간 0.027초

병렬 유한요소 모형을 이용한 황해의 실시간 조석 및 태풍해일 산정 (Realtime Tide and Storm-Surge Computations for the Yellow Sea Using the Parallel Finite Element Model)

  • 변상신;최병호;김경옥
    • 한국군사과학기술학회지
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    • 제12권1호
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    • pp.29-36
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    • 2009
  • Realtime tide and storm-surge computations for the Yellow Sea were conducted using the Parallel Finite Element Model. For these computations a high resolution grid system was constructed with a minimum node interval of loom in Gyeonggi Bay. In the modeling, eight main tidal constituents were analyzed and their results agreed well with the observed data. The realtime tide computation with the eight main tidal constituents and the storm-surge simulation for Typhoon Sarah(1959) were also conducted using parallel computing system of MPI-based LINUX clusters. The result showed a good performance in simulating Typhoon Sarah and reducing the computation time.

Numerical study of wake structure behind a square cylinder at high Reynolds number

  • Lee, Sungsu
    • Wind and Structures
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    • 제1권2호
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    • pp.127-144
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    • 1998
  • In this paper, the wake structures behind a square cylinder at the Reynolds number of 22,000 are simulated using the large eddy simulation, and the main features of the wake structure associated with unsteady vortex-shedding are investigated. The Smagorinsky model is used for parametrization of the subgrid scales. The finite element method with isoparametric linear elements is employed in the computations. Unsteady computations are performed using the explicit method with streamline upwind scheme for the advection term. The time integration incorporates a subcycling strategy. No-slip condition is enforced on the wall surface. A comparative study between two-and three-dimensional computations puts a stress on the three-dimensional effects in turbulent flow simulations. Simulated three-dimensional wake structures are compared with numerical and experimental results reported by other researchers. The results include time-averaged, phase-averaged flow fields and numerically visualized vortex-shedding pattern using streaklines. The results show that dynamics of the vortex-shedding phenomenon are numerically well reproduced using the present method of finite element implementation of large eddy simulation.

Nonlinear Conte-Zbilut-Federici (CZF) Method of Computing LF/HF Ratio: A More Reliable Index of Changes in Heart Rate Variability

  • Vernon Bond, Jr;Curry, Bryan H;Kumar, Krishna;Pemminati, Sudhakar;Gorantla, Vasavi R;Kadur, Kishan;Millis, Richard M
    • 대한약침학회지
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    • 제19권3호
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    • pp.207-212
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    • 2016
  • Objectives: Acupuncture treatments are safe and effective for a wide variety of diseases involving autonomic dysregulation. Heart rate variability (HRV) is a noninvasive method for assessing sympathovagal balance. The low frequency/high frequency (LF/HF) spectral power ratio is an index of sympathovagal influence on heart rate and of cardiovascular health. This study tests the hypothesis that from rest to 30% to 50% of peak oxygen consumption, the nonlinear Conte-Zbilut-Federici (CZF) method of computing the LF/HF ratio is a more reliable index of changes in the HRV than linear methods are. Methods: The subjects of this study were 10 healthy young adults. Electrocardiogram RR intervals were measured during 6-minute periods of rest and aerobic exercise on a cycle ergometer at 30% and 50% of peak oxygen consumption ($VO_{2peak}$). Results: The frequency domain CZF computations of the LF/HF ratio and the time domain computations of the standard deviation of normal-to-normal intervals (SDNN) decreased sequentially from rest to 30% $VO_{2peak}$ (P < 0.001) to 50% $VO_{2peak}$ (P < 0.05). The SDNN and the CZF computations of the LF/HF ratio were positively correlated (Pearson's r = 0.75, P < 0.001). fast Fourier transform (FFT), autoregressive (AR) and Lomb periodogram computations of the LF/HF ratio increased only from rest to 50% $VO_{2peak}$. Conclusion: Computations of the LF/HF ratio by using the nonlinear CZF method appear to be more sensitive to changes in physical activity than computations of the LF/HF ratio by using linear methods. Future studies should determine whether the CZF computation of the LF/HF ratio improves evaluations of pharmacopuncture and other treatment modalities.

Bank 구조를 이용한 Novel STOP-&-GO (A Study of Novel Stop-&-Go Equalization Using Bank Structure)

  • 조경철;강영창김선형
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 1998년도 추계종합학술대회 논문집
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    • pp.1195-1198
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    • 1998
  • A Novel Stop-&-Go Algorithm which incorporate a Bank structure for blind equalization is investigated in this paper. 16-QAM and $\pi/4-DQPSK$ modulation used in this paper. A Proposed novel algorithm of characteristic is high speed transfer by implementation of the equalization algorithm with less computations capacity. The computer simulations result reveal that the proposed Novel Stop-&-Go shows the comparable performance to the conventional Stop-&-Go, while requiring much less computations.

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A programmable Soc for Var ious Image Applications Based on Mobile Devices

  • Lee, Bongkyu
    • 한국멀티미디어학회논문지
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    • 제17권3호
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    • pp.324-332
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    • 2014
  • This paper presents a programmable System-On-a-chip for various embedded applications that need Neural Network computations. The system is fully implemented into Field-Programmable Gate Array (FPGA) based prototyping platform. The SoC consists of an embedded processor core and a reconfigurable hardware accelerator for neural computations. The performance of the SoC is evaluated using real image processing applications, such as optical character recognition (OCR) system.

Computational Reduction in Keyword Spotting System Based on the Bucket Box Intersection (BBI) Algorithm

  • Lee, Kyo-Heok;Kim, Hyung-Soon
    • The Journal of the Acoustical Society of Korea
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    • 제19권2E호
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    • pp.27-31
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    • 2000
  • Evaluating log-likelihood of Gaussian mixture density is major computational burden for the keyword spotting system using continuous HMM. In this paper, we employ the bucket box intersection (BBI) algorithm to reduce the computational complexity of keyword spotting. We make some modification in implementing BBI algorithm in order to increase the discrimination ability among the keyword models. According to our keyword spotting experiments, the modified BBI algorithm reduces 50% of log-likelihood computations without performance degradation, while the original BBI algorithm under the same condition reduces only 30% of log-likelihood computations.

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유전자 알고리즘과 상용설계도구를 이용한 SRM의 최적화 설계 (Optimal Design of SRM using Evolutionary Computations and CAD program)

  • 김태형;안진우;황기현
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2004년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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    • pp.21-23
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    • 2004
  • In this paper, an optimal design method to have good performance is researched. The parameters which are sensitive to the performance are examined and selected by using evolutionary computations and commercial CAD program to have good performance. Design method Simulated are compared with conrrentional procedure.

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Development of AC Transmassion Line Audible Noise Prediction Formulas Using Evolutionary Computations

  • Yang, Kwang-Ho;Park, June-Ho;Hwang, Gi-Hyun;Kim, Jeong-Boo
    • Journal of Electrical Engineering and information Science
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    • 제2권6호
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    • pp.116-122
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    • 1997
  • The audible noise produced by corona discharge in high voltage transmission lines is the most important line design consideration. In this paper, more accurate and useful formulas for predicting the A-weighted audible noise during heavy and light rain in alternative current (AC) transmission lines are proposed through comparison with the existing formulas. The proposed formulas are developed by the applications of evolutionary computations (ECs) to audible noise data base from long-term measurement.

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NUMERICAL METHODS FOR COMPUTATIONS OF NONEQUILIBRIUM HYPERSONIC FLOW AROUND BODIES

  • Park, Tae-Hoon;Kim, Pok-Son
    • Journal of applied mathematics & informatics
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    • 제9권1호
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    • pp.1-13
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    • 2002
  • In this paper we present numerical methods fur computations of nonequilibrium hypersonic flow of air around bodies including chemical reaction effects and present numerical result of the flow over concave corners. We developed implicit finite difference method to overcome numerical difficulties with the lack of resolution behind the shock and near the body. Using our method we were able to find details of the flow properties near the shock and body and were able to continue the computation of the flow for a long distance from the corner of the body.

임베디드 디바이스에서 음성 인식 알고리듬 구현을 위한 부동 소수점 연산의 고정 소수점 연산 변환 기법 (Automatic Floating-Point to Fixed-Point Conversion for Speech Recognition in Embedded Device)

  • 윤성락;유창동
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2007년도 하계종합학술대회 논문집
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    • pp.305-306
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    • 2007
  • This paper proposes an automatic conversion method from floating-point value computations to fixed-point value computations for implementing automatic speech recognition (ASR) algorithms in embedded device.

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