• Title/Summary/Keyword: Latin

Search Result 907, Processing Time 0.043 seconds

Design Optimization of a Channel Roughened by Dimples Using Weighted Average Surrogate Model (가중평균 대리모델을 사용한 딤플 유로의 최적설계)

  • Lee, Ki-Don;Kim, Kwang-Yong
    • The KSFM Journal of Fluid Machinery
    • /
    • v.11 no.1
    • /
    • pp.52-60
    • /
    • 2008
  • Staggered dimples printed on opposite walls of an internal cooling channel are formulated numerically and optimized to enhance heat transfer performance. Nusselt number and friction factor based objectives are considered and a weighted average surrogate model is used to approximate the data generated by numerical simulation. The dimpled channel shape is defined by three geometric design variables, and the design point within design space are selected using Latin hypercube sampling. A weighted-sum method for multi-objective optimization is applied to integrate multiple objectives into a single objective. By the optimization, the objective function value is improved largely and heat transfer rate is increase much higher than pressure loss increase due to shape deformation. Channel with vertically non-symmetric optimum dimples is tested and found that the best appears if dimples on opposite wall are displaced by one quarter of dimple spacing.

격자기반(Lattice-based) 라틴 하이퍼큐브(Latin hypercube) 계획의 제안

  • 황현식;박정수
    • Proceedings of the Korean Statistical Society Conference
    • /
    • 2001.11a
    • /
    • pp.115-120
    • /
    • 2001
  • 라틴 하이퍼큐브 실험계획은 전산실험을 위하여 Mckay, Beckman과 Conover(1979)에 의해 고안된 방법으로 실험을 한번 시행하는데 많은 시간과 비용이 들거나 인자가 많은 실험에 효율적으로 사용할 수 있다. 하지만 이 실험계획 역시 실험영역 전체에서 골고루 배치되지 않을 가능성이 있으므로 이를 보완하려는 시도가 이루어져 왔으며, 여기서는 good lattice points(glp)와 계통추출을 응용하여 격자기반(lattice-based) Lhd의 두 가지 방법을 제안하였다. 모의실험 결과 glp 실험계획을 응용한 "방법 1"은 모형을 가정한 엔트로피에 기초한 최적 기준으로 검토한 경우 우수하였다. "방법 2"는 표본조사에 널리 쓰이는 계통추출을 응용하였으며 입력변수가 각기 다른 9개의 실험함수에 관하여 표본 평균의 추정치와 분산, MSE를 비교한 결과, 다른 실험계획들보다 우수하였다. 이 결과는 실험점이 실험영역 전체에서 골고루 퍼져서 나타난 것으로 보이며, 향후 전산실험계획에서의 응용을 기대할 수 있다.

  • PDF

On the Existence of Maximal Fan Design

  • Kim, Hyoungsoon;Park, Dongkwon;Kim, KyungHee
    • Communications for Statistical Applications and Methods
    • /
    • v.9 no.2
    • /
    • pp.347-354
    • /
    • 2002
  • An n-point design is maximal fan if all the models with n-terms satisfying the divisibility condition are estimable. Such designs tend to be space filling and look very similar to the ″Latin-hypercube″ designs used in computer experiments. Caboara, Pistone, Riccomago and Wynn (1997) conjectured that a maximal fan design on an integer grid exists for any n and m, where m is the number of factors. In this paper we examine the relationship between maximal fan design and latin-hypercube to give a partial solution for the conjecture.

반응표면법과 Monte Carlo 모사를 이용한 불확실한 변동의 강건설계를 위한 확률적 민감도의 제안

  • 백석흠;이경영;조석수;주원식
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2004.05a
    • /
    • pp.89-89
    • /
    • 2004
  • 결정적인 알고리즘과 입력정보의 사용은 평가된 해석과 실제 시스템 값과의 차이로 잘못된 결론을 이끌지도 모른다. 실제 시스템은 대부분 각각의 입력 매개변수들(input parameters)과 관계된 넓은 공차 영역(tolerance band)을 가지고 있어서 입력정보로 하나의 단일한 값을 할당하는 것이 어렵다. 단일 입력에 대한 한가지 해는 변동의 이해 없이 제한된 값이라는 것을 인식할 필요가 있는데 대개 결정론적 설계는 형상과 관련된 치수변동, 항복강도나 부재의 밀도, 탄성계수와 같은 재료 물성치의 불확실성(uncertainty)과 시스템에 작용하는 하중의 변동 등을 직접 고려하지 않고 설계를 수행하기 때문에 수용할 수 있는 오차의 범위 안에서 시스템의 응답을 정확히 평가하기가 쉽지 않았다.(중략)

  • PDF

Quantifying Uncertainty for the Water Balance Analysis (물수지 분석을 위한 불확실성 정량화 방안)

  • Lee, Seung Uk;Kim, Young-Oh;Lee, Dong Ryul
    • Proceedings of the Korea Water Resources Association Conference
    • /
    • 2004.05b
    • /
    • pp.277-281
    • /
    • 2004
  • 수자원장기종합계획에서는 물의 과부족 또는 가용한 물을 정량적으로 평가하기 위해 물수지 분석을 실시한다. 물수지 분석은 미래 예측되는 용수수요량과 공급가능량을 비교하는 단순한 과정이지만, 분석 과정에 포함되어 있는 자료와 모형의 불확실성으로 인하여 물수지 분석을 실시한 각종 보고서마다 서로 다른 결과를 보여주고 있어 국민의 신뢰를 얻지 못한 실정이다. 본 연구에서는 Monte Carlo simulation 기법 중 Latin Hypercube Sampling에 기반한 확률적 모사로 물수지의 불확실성을 표현하고, 이를 기존에서 제시한 단일 물부족량과 비교하여 불확실성의 범위와 특성을 분석하였다. 또한 민감도 분석을 수행함으로써 입력변수들 간의 상대적 중요도를 산정하여 수자원계획 수립시 투자 우선순위를 제시하였다.

  • PDF

Durability Assesment for Concrete Structures Exposed to Chloride Attack Using a Bayesian Approach (베이지안 기법을 이용한 염해 콘크리트 구조물의 내구성 평가)

  • Jung, Hyun-Jun;Zi, Goang-Seup
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • 2007.04a
    • /
    • pp.589-594
    • /
    • 2007
  • This paper is shown new method for durability assesment and design have been noticed to be very valuable has been successfully applied to predict concrete structures. This paper provides that a new approach for predicting the corrosion durability of reinforced concrete structures exposed to chloride attack. In this method, the prediction can be updated successive1y by the Bayesian theory when additional data are available. The stochastic properties of model parameters are explicitly taken into account into the model the probability of the durability limit is determined from the samples obtained from the Latin hypercube sampling technique. The new method may be very useful in designing important concrete structures and help to predict the remaining service life of existing concrete structures under chloride attack environments.

  • PDF

Collision-free Interleaver Composed of a Latin Square Matrix for Parallel-architecture Turbo Codes (병렬 처리 구조 터보 부호에서 라틴 방진 행렬로 구성된 충돌 방지 인터리버)

  • Kim, Dae-Son;Oh, Hyun-Young;Song, Hong-Yeop
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.33 no.2C
    • /
    • pp.161-166
    • /
    • 2008
  • In the parallel-architecture turbo codes, the constituent interleaver must avoid memory collision. This paper proposes a collision-free interleaver structure composed of a Latin square matrix and pre-designed interleavers. Our proposed interleavers can be easily optimized for various information block sizes and for various degrees of parallelism. Their performances were evaluated by computer simulation.

Comparison of Latin Hypercube Sampling and Simple Random Sampling Applied to Neural Network Modeling of HfO2 Thin Film Fabrication

  • Lee, Jung-Hwan;Ko, Young-Don;Yun, Il-Gu;Han, Kyong-Hee
    • Transactions on Electrical and Electronic Materials
    • /
    • v.7 no.4
    • /
    • pp.210-214
    • /
    • 2006
  • In this paper, two sampling methods which are Latin hypercube sampling (LHS) and simple random sampling were. compared to improve the modeling speed of neural network model. Sampling method was used to generate initial weights and bias set. Electrical characteristic data for $HfO_2$ thin film was used as modeling data. 10 initial parameter sets which are initial weights and bias sets were generated using LHS and simple random sampling, respectively. Modeling was performed with generated initial parameters and measured epoch number. The other network parameters were fixed. The iterative 20 minimum epoch numbers for LHS and simple random sampling were analyzed by nonparametric method because of their nonnormality.

A Robust and Computationally Efficient Optimal Design Algorithm of Electromagnetic Devices Using Adaptive Response Surface Method

  • Zhang, Yanli;Yoon, Hee-Sung;Shin, Pan-Seok;Koh, Chang-Seop
    • Journal of Electrical Engineering and Technology
    • /
    • v.3 no.2
    • /
    • pp.207-212
    • /
    • 2008
  • This paper presents a robust and computationally efficient optimal design algorithm for electromagnetic devices by combining an adaptive response surface approximation of the objective function and($1+{\lambda}$) evolution strategy. In the adaptive response surface approximation, the design space is successively reduced with the iteration, and Pareto-optimal sampling points are generated by using Latin hypercube design with the Max Distance and Min Distance criteria. The proposed algorithm is applied to an analytic example and TEAM problem 22, and its robustness and computational efficiency are investigated.

Shape Optimization of High Voltage Gas Circuit Breaker Using Kriging-Based Model And Genetic Algorithm (크리깅 메타모델과 유전자 알고리즘을 이용한 초고압 가스차단기의 형상 최적 설계)

  • Kwak, Chang-Seob;Kim, Hong-Kyu;Cha, Jeong-Won
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.62 no.2
    • /
    • pp.177-183
    • /
    • 2013
  • We describe a new method for selecting design variables for shape optimization of high-voltage gas circuit breaker using a Kriging meta-model and a genetic algorithm. Firstly we sample balance design variables using the Latin Hypercube Sampling. Secondly, we build meta-model using the Kriging. Thirdly, we search the optimal design variables using a genetic algorithm. To obtain the more exact design variable, we adopt the boundary shifting method. With the proposed optimization frame, we can get the improved interruption design and reduce the design time by 80%. We applied the proposed method to the optimization of multivariate optimization problems as well as shape optimization of a high - voltage gas circuit breaker.