• 한국가시화정보학회지
• /
• 제2권1호
• /
• pp.8-11
• /
• 2004

Conditional sampling measurement is required for conditional averages as well as unconditional Favre averages to resolve different flame structures of turbulent combustion. A Favre average can be obtained as an integral of conditional average and Favre PDF in terms of the mixture fraction, which is a preferred choice as a sampling variable in diffusion controlled turbulent combustion. MILD combustion data are presented as an example for a conditionally averaged data set and comparison with CMC calculation results.

• Structural Engineering and Mechanics
• /
• 제32권1호
• /
• pp.55-69
• /
• 2009

A quasi ideal importance sampling simulation method combined in the conditional expectation is proposed for the structural reliability estimation. The quasi ideal importance sampling joint probability density function (p.d.f.) is so composed on the basis of the ideal importance sampling concept as to be proportional to the conditional failure probability multiplied by the p.d.f. of the sampling variables. The respective marginal p.d.f.s of the ideal importance sampling joint p.d.f. are determined numerically by the simulations and partly by the piecewise integrations. The quasi ideal importance sampling simulations combined in the conditional expectation are executed to estimate the failure probabilities of structures with multiple failure surfaces and it is shown that the proposed method gives accurate estimations efficiently.

• 전자공학회논문지SC
• /
• 제38권3호
• /
• pp.31-39
• /
• 2001

본 논문에서는 CMOS 이미지 센서의 동작 범위(Dynamic Range; DR)를 높이기 위해서， multiple sampling 방법과 조건적 reset 기능을 갖는 새로운 픽셀 회로를 제안한다. 제안된 구조는 한 번의 integration 시간 내에서 픽셀의 출력이 일정한 간격으로 여러 번 sampling되고 sampling된 각 신호는 기준 전압과 비교되며 이 결과에 따라 해당 픽셀을 rest 할지의 여부가 결정된다. 제안된 방법을 사용하면 이미지 센서의 최대 DR은 축적 기간 동안의 총 sampling 회수인 N 배로 증가될 수 있다. 테스트 칩은 0.65-${\mu}m$ CMOS 공정(2-P, 2-M)으로 제작되었으며 이에 대한 측정결과로 본 논문의 알고리듬이 DR의 증가에 효과적임을 확인하였다.

• Journal of the Korean Data and Information Science Society
• /
• 제27권5호
• /
• pp.1155-1168
• /
• 2016

기상 자료의 경우 한 지역의 기후가 인접지역의 기후와 비슷한 양상을 띄고 각 지역의 확률 밀도 함수 (probability density function)가 잘 알려진 확률 모형을 따르지 않는다는 것이 알려져 있다. 본 논문에서는 이러한 특성을 고려하여 이상 기후 현상이 뚜렷히 나타나는 여름철 평균 극한 기온(extreme temperature)의 확률 밀도 함수를 추정하고자 한다. 이를 위하여 공간적 상관관계 (spatial correlation)를 고려하는 비모수 베이지안 (nonparametric Bayesian) 모형인 조건부 자기회귀 종추출 혼합모형 (mixtures of conditional autoregression species sampling model)을 이용하였다. 자료는 이스트앵글리아 대학교 (University of East Anglia)에서 제공하는 전 지구의 최대 기온과 최소 기온자료 중 우리나라에 해당하는 지역의 자료를 사용하였다.

• Communications for Statistical Applications and Methods
• /
• 제5권1호
• /
• pp.107-120
• /
• 1998

This research aims here to develop a certain extended double sampling plan, EDS, which is an extension of ordinary double sampling plan in the sense that the second-stage sampling effort and second-stage critical value are allowed to depend on the point at which the first-stage continuation region is traversed. For purpose of comparison, single sampling plan, optimal ordinary double sampling plan(ODS) and sequential probability ratio test are considered with the same overall error rates, respectively. It is observed that the EDS idea allows less sampling effort than the optimal ODS.

• Wind and Structures
• /
• 제18권6호
• /
• pp.651-668
• /
• 2014

Wind tunnel tests are conducted to investigate the wind loads on vertical fixed-roof cylindrical tanks with a very low aspect ratio of 0.275, which is a typical ratio for practical tanks with a volume of $100,000m^3$. Both the flat-roof tank and the dome-roof tank are investigated in present study. The first four moments of the measured wind pressure, including the mean and normalized deviation pressure, kurtosis and skewness of the pressure signal, are obtained to study the feature of the wind loads. It is shown that the wind loads are closely related to the behavior of flow around the structure. For either tank, the mean wind pressures on the cylinder are positive on the windward area and negative on the sides and the wake area, and the mean wind pressures on the whole roof are negative. The roof configurations have no considerable influence on the mean pressure distributions of cylindrical wall in general. Highly non-Gaussian feature is found in either tank. Conditional sampling technique, envelope method, and the proper orthogonal decomposition (POD) analysis are employed to investigate the characteristics of wind loads on the cylinder in more detail. It is shown that the patterns of wind pressure obtained from conditional sampling are similar to the mean pressure patterns.An instantaneous pressure coefficient can present a wide range from the maximum value to the minimum value. The quasi-steady assumption is not valid for structures considered in this paper according to the POD analysis.

• ETRI Journal
• /
• 제14권4호
• /
• pp.19-27
• /
• 1992

Since. as is well known, direct computation of the reliability for a large-scaled and complex net work generally requires exponential time, a variety of alternative methods to estimate the network reliability using simulation have been proposed. Monte Carlo sampling is the major approach to estimate the network reliability using simulation. In the paper, a dynamic Monte Carlo sampling method, called conditional minimal cut set (CMCS) algorithm, is suggested. The CMCS algorithm simulates a minimal cut set composed of arcs originated from the (conditional) source node until s-t connectedness is confirmed, then reduces the network on the basis of the states of simulated arcs. We develop the importance sampling estimator and the total hazard estimator and compare the performance of these simulation estimators. It is found that the CMCS algorithm is useful in reducing variance of network reliability estimator.

• 한국지반공학회논문집
• /
• 제23권3호
• /
• pp.51-59
• /
• 2007

다양한 불확실성을 체계적으로 반영하는 신뢰성 기반 해석기법을 사면안정 해석의 한 형식으로 제시한다. 통계오차, 공간 변동성, 그리고 공간 평균의 효과를 고려할 수 있는 지반특성 표현식이 사용되었다. 여러 가지 형식의 지반특성 표현식을 이용하여 사면안정 신뢰성 해석을 수행한 결과 통계오차, 공간적 상관성, 그리고 조건부 해석기법을 사용할 경우가 기존의 단순 확률변수 기법에 비해 상당히 작은 파괴확률을 제시한다는 사실이 밝혀졌다. 이 결과는 사면안정 해석에서 공간적 변동성과 통계오차가 합리적으로 고려되어야 한다는 점을 제시한다.

• 한국지진공학회논문집
• /
• 제25권4호
• /
• pp.179-189
• /
• 2021

Conditional spectra (CS) are applied to the seismic fragility assessment of a nuclear power plant (NPP) containment building for comparison with a relevant conventional uniform hazard response spectrum (UHRS). Three different control frequencies are considered in developing conditional spectra. The contribution of diverse magnitudes and epicentral distances is identified from deaggregation for the UHRS at a control frequency and incorporated into the conditional spectra. A total of 30 ground motion records are selected and scaled to simulate the probability distribution of each conditional spectra, respectively. A set of lumped mass stick models for the containment building are built considering nonlinear bending and shear deformation and uncertainty in modeling parameters using the Latin hypercube sampling technique. Incremental dynamic analysis is conducted for different seismic input models in order to estimate seismic fragility functions. The seismic fragility functions and high confidence of low probability of failure (HCLPF) are calculated for different seismic input models and analyzed comparatively.

• Communications for Statistical Applications and Methods
• /
• 제22권6호
• /
• pp.557-573
• /
• 2015

In this paper we develop a Bayesian inference for a multiplicative double seasonal autoregressive (DSAR) model by implementing a fast, easy and accurate Gibbs sampling algorithm. We apply the Gibbs sampling to approximate empirically the marginal posterior distributions after showing that the conditional posterior distribution of the model parameters and the variance are multivariate normal and inverse gamma, respectively. The proposed Bayesian methodology is illustrated using simulated examples and real-world time series data.