• 제목/요약/키워드: Theoretical Computation

검색결과 198건 처리시간 0.027초

On the SNU uvby,$H_{\beta}$ Filter System

  • Kim, Hee-Soo;Lee, See-Woo
    • 천문학논총
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    • 제2권1호
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    • pp.1-12
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    • 1985
  • We examined the characteristics of the SNU uvby, $H_{\beta}$ filter system through the computation of theoretical photometric indices and the transformation of the observed instrumental system to the natural and standard systems.

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세라믹 열교환기의 이론해석 및 CFD 시뮬레이션 (A theoretical Analysis and CFD Simulation on the Ceramic Heat Exchanger)

  • 팽진기;윤영환
    • 설비공학논문집
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    • 제21권5호
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    • pp.282-290
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    • 2009
  • A ceramic monolith heat exchanger is studied to find the performance of heat transfer and pressure drop by numerical computation and $\xi$-NTU method. The numerical computation was performed throughout the domain including fluid region in exhaust gas-side rectangular ducts, ceramic core and fluid region in air-side rectangular duct with the air and exhaust in cross flow direction. In addition, the heat exchanger was also analyzed to estimate the performance by conventional $\xi$-NTU method with several Nusselt number correlations for flow in rectangular duct from literature. By comparisons of both performances by the numerical computation and the $\xi$-NTU method, the effectiveness by $\xi$-NTU method was closest to the result by numerical computation within a relative error of 2.14% when Stephan's Nusselt number correlation was adopted to the $\xi$-NTU method among the several correlations.

불균형(不均衡) 일원(一元) 변량모형(變量模型)에서 추정방법(推定方法)에 따른 분산성분(分散成分)의 추정량(推定量)이 음(陰)이 될 확률(確率)의 계산(計算) (On the Probability of the Estimate of Variance Components that is Negative in Unbalanced One-Way Random Model)

  • 송규문
    • Journal of the Korean Data and Information Science Society
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    • 제4권
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    • pp.121-130
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    • 1993
  • 불균형 일원 변량모형에서 AOV추정량과 사전값이 0, 1, ${\infty}$인 MINQUE에 국한하여 정규분포를 가정할 때 분산성분의 추정량이 음이 될 이론적 확률을 구하고, 비정규분포에 대해서는 모의실험을 통해 추정량이 음이 될 확률을 구하였다. 이 때 정차분포에서의 이론적 확률과 모의실험에 의해 계산된 확률간에 유의한 차이가 없고 표본수, 수준수 그리고 ${\rho}$가 커지면 각 추정량은 음이 될 확률이 작아지며, 고려된 추정량 중에서 AOV추정량이 대부분의 경우에 음이 될 확률이 가장 작게 나타났다.

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Multi-level approach for parametric roll analysis

  • Kim, Tae-Young;Kim, Yong-Hwan
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제3권1호
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    • pp.53-64
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    • 2011
  • The present study considers multi-level approach for the analysis of parametric roll phenomena. Three kinds of computation method, GM variation, impulse response function (IRF), and Rankine panel method, are applied for the multi-level approach. IRF and Rankine panel method are based on the weakly nonlinear formulation which includes nonlinear Froude-Krylov and restoring forces. In the computation result of parametric roll occurrence test in regular waves, IRF and Rankine panel method show similar tendency. Although the GM variation approach predicts the occurrence of parametric roll at twice roll natural frequency, its frequency criteria shows a little difference. Nonlinear roll motion in bichromatic wave is also considered in this study. To prove the unstable roll motion in bichromatic waves, theoretical and numerical approaches are applied. The occurrence of parametric roll is theoretically examined by introducing the quasi-periodic Mathieu equation. Instability criteria are well predicted from stability analysis in theoretical approach. From the Fourier analysis, it has been verified that difference-frequency effects create the unstable roll motion. The occurrence of unstable roll motion in bichromatic wave is also observed in the experiment.

A Joint Allocation Algorithm of Computing and Communication Resources Based on Reinforcement Learning in MEC System

  • Liu, Qinghua;Li, Qingping
    • Journal of Information Processing Systems
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    • 제17권4호
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    • pp.721-736
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    • 2021
  • For the mobile edge computing (MEC) system supporting dense network, a joint allocation algorithm of computing and communication resources based on reinforcement learning is proposed. The energy consumption of task execution is defined as the maximum energy consumption of each user's task execution in the system. Considering the constraints of task unloading, power allocation, transmission rate and calculation resource allocation, the problem of joint task unloading and resource allocation is modeled as a problem of maximum task execution energy consumption minimization. As a mixed integer nonlinear programming problem, it is difficult to be directly solve by traditional optimization methods. This paper uses reinforcement learning algorithm to solve this problem. Then, the Markov decision-making process and the theoretical basis of reinforcement learning are introduced to provide a theoretical basis for the algorithm simulation experiment. Based on the algorithm of reinforcement learning and joint allocation of communication resources, the joint optimization of data task unloading and power control strategy is carried out for each terminal device, and the local computing model and task unloading model are built. The simulation results show that the total task computation cost of the proposed algorithm is 5%-10% less than that of the two comparison algorithms under the same task input. At the same time, the total task computation cost of the proposed algorithm is more than 5% less than that of the two new comparison algorithms.

AVL 트리를 사용한 효율적인 스트림 큐브 계산 (Efficient Computation of Stream Cubes Using AVL Trees)

  • 김지현;김명
    • 정보처리학회논문지D
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    • 제14D권6호
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    • pp.597-604
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    • 2007
  • 스트림 데이터는 끊임없이 고속으로 생성되는 데이터로써 최근 이러한 데이터를 분석하여 부가가치를 얻고자 하는 노력이 활발히 진행 중 이다. 본 연구에서는 스트림 데이터의 다차원적 분석을 위해 큐브를 고속으로 계산하는 방법을 제안한다. 스트림 데이터는 비즈니스 데이터와는 달리 정렬되지 않은 채로 도착하며, 데이터의 끝에 도달하지 않은 상태에서는 집계 결과를 낼 수 없어서, 고속으로 집계하는 과정에서 저장 공간의 낭비를 심하게 초래한다. 또한 큐브에 속한 집계 테이블들을 모두 생성하는 것은 시간/공간 측면에서 비효율적이라는 점이 지적되고 있다. 이러한 문제를 해결하기 위해 본 연구에서는 기존 연구들과 마찬가지로 큐브에 포함시킬 집계 테이블들을 사용자가 미리 정하도록 하였고, 정렬되지 않은 스트림 데이터를 고속으로 집계하는 과정에서 배열과 AVL 트리들로 구성된 자료구조를 집계 테이블의 임시 저장소로 사용하였다. 제안한 알고리즘은 생성하려는 큐브가 메모리에 상주할 수 없을 정도로 큰 경우에도 집계 연산을 수행할 수 있다. 이론적 분석과 성능 평가를 통해 제안한 큐브 계산 알고리즘이 실용적임을 입증하였다.

An Account of LAD with ESL/SLI Data

  • Kim, Jeong-Seok;Han, Ho
    • 영어어문교육
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    • 제9권1호
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    • pp.49-66
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    • 2003
  • This paper explores the language acquisition mechanism within a recent theoretical nativist framework that assumes some computational principles. We will review previous accounts of the logical problem of language acquisition, arguing that language acquisition is part of general cognitive mechanism or at least associated with maturation of cognitive skills. For a theoretical framework, we will adopt the minimalist program and its principles. To support our theoretical argument, we will introduce empirical evidence from ESL (English as a Second Language) and SLI (Specific Language Impairment) data. The two types of data will illustrate that there might be some relationship between the development of language skills and that of the cognitive skills.

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Theoretical formulation for vehicle-bridge interaction analysis based on perturbation method

  • Tan, Yongchao;Cao, Liang;Li, Jiang
    • Structural Engineering and Mechanics
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    • 제82권2호
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    • pp.191-204
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    • 2022
  • A three-mass vehicle model including one rigid mass and two unsprung masses is adopted to predict the vehicle-bridge interaction (VBI) and to establish the nonlinear coupled governing equations. To overcome the numerical instability and large computation problems concerning the vehicle-bridge system, the perturbation method is used to convert the nonlinear coupled governing equations into a set of linear uncoupled equations. Formulas for bridge's natural frequencies considering both the VBI and the dynamic responses of bridge and vehicle are proposed. Compared with the numerical results obtained by the Newmark-β method, the theoretical solutions for natural frequencies and dynamic responses are validated. The effects of the important factors of unsprung mass, vehicle damping, surface irregularity on the natural frequencies and dynamic responses of bridge and vehicle are discussed, based on the theoretical solutions.

실시간 시스템에서 여러 부정확한 스케쥴링 기법하에서의 부정확한 확률에 관한 비교 분석 (Comparative Analysis on Imprecision Probability Under Several Imprecise Scheduling Schemes in Real Time Systems)

  • 안귀임;고건
    • 한국통신학회논문지
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    • 제19권7호
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    • pp.1304-1320
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    • 1994
  • 실시간 시스템에는 정확한 계산 기법과 부정확한 계산 기법이 있다. 부정확한 계산 기법은 실시간 시스템에서 스케쥴링의 유연성을 제공하는 수단이다. 지금까지 큐잉이론을 이용한 부정확한 스케쥴링에 관한 연구들은 태스크들의 평균 결과의 질과 평균 대기시간을 정충한 때의 비용과 장점들을 명확하게 수량화하는 것들이었다. 이논문은 두개의 부정확한 스케쥴링 방법을 사용할 때, 어떤 태스크가 부정확한 계산이 될 부정확한 확률들을 구하였으며 또한, 이런 두 방법의 부정확한 확률들의 여러 단조형 부정확한 시스템 매개변수들에 대한 의존성을 비교 분석하였다.

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밀봉제 도포용 마이크로 노즐 설계를 위한 유동해석 (NUMERICAL INVESTIGATION OF THE FLOW IN A MICRONOZZLE FOR SEAL DISPENSER)

  • 박규진;곽호상;손병철;김경진
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2007년도 추계 학술대회논문집
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    • pp.236-242
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    • 2007
  • A theoretical and numerical investigation is performed on the flow in a micronozzle for precision-controlled seal dispenser. The working fluid is a highly viscous epoxy used as sealant in producing LCD panels, which contains a number of tiny solid spacers. Flow analysis is conducted in order to achieve the optimal design oj internal geometry of a nozzle. A simplified design analysis methodology is proposed for predicting the flow in the nozzle based on the assumption that the Reynolds number is much less than O(1). The parallel numerical computations are performed by using a CFD package FLUENT. Comparison discloses that the theoretical model gives a good prediction on the distribution of pressure and wall shear stress in the nozzle. However, the theoretical model has a difficulty in predicting the maximum wall shear stress as found in a limited region near edge by numerical computation. The theoretical and numerical simulations provide the good guideline for designing a dispensing micronozzle.

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