• The Korean Journal of Applied Statistics
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• v.13 no.1
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• pp.81-96
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• 2000

본 논문은 의학분야에서 주로 사용되는 메타분석 중 그룹화 임의효과 모형(grouped random effects model)을 프라빗 연결함수(probit link function)를 이용하여 베이즈적 관점에서 연구하였다. 이때 프라빗 함수를 강요하기 위해 잠재변수를 정의하였고, 사전 분포를 달리한 세가지 모형을 고려하였다. 주어진 세가지 모형들에게서 적합한 모형 선택을 위하여 베이즈 인자(Bayes factor, BF)와 유사베이즈 인자(pseudo-Bayes factor, PsBF)를 이용하였다. 깁스샘플러와 메트로폴리스 알고리즘을 이용하여 베이지안 계산상의 어려움을 해결하였다. 예로써, 새로운 간질약에 대한 효과를 조사하기 위하여 앞에서 제시된 방법으로 해석하였다.

• The Korean Journal of Applied Statistics
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• v.28 no.2
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• pp.137-149
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• 2015

Flood planning needs to recognize trends for extreme precipitation events. Especially, the r-year return level is a common measure for extreme events. In this paper, we present a nonstationary temporal model for precipitation return levels using a hierarchical Bayesian modeling. For intensity, we model annual maximum daily precipitation measured in Korea with a generalized extreme value (GEV). The temporal dependence among the return levels is incorporated to the model for GEV model parameters and a linear model with autoregressive error terms. We apply the proposed model to precipitation data collected from various stations in Korea from 1973 to 2011.

• Korean Journal of Optics and Photonics
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• v.15 no.5
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• pp.461-468
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• 2004

A finite model eye of visual acuity 24/20 in emmertropia was presented. We determined the image intensity profile on retina using optical transfer function of model eye, and compared with clinical data. The retinal contrast sensitivity function based on the Stiles-Crawford effect, photopic response, diffraction, aberration, retinal contrast sensitivity, and pupil size is calculated. Visual acuity for human eye could be predicted by examining the modulation transfer function of a bar target and retinal contrast sensitivity function. This visual acuity was evaluated for pupil diameters ranging from 1 to 8 mm.

• Communications for Statistical Applications and Methods
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• v.3 no.3
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• pp.1-9
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• 1996

본 논문에서는 일반화 회귀모형의 회귀모수${\beta}$에 대한 사전정보의 형태에 따른 각 추정량들에 대하여 연구하였다. 먼저 사전정보가 ${\beta}$에 대한 사전분포로 주어지는 경우에 해당하는 베이지안 회귀추정량을 제시하였고, 다른 하나는 ${\beta}$에 대한 사전정보모형으로 선형회귀모형식이 주어진 경우의 일반화 혼합회귀추정량에 대하여 연구하였다. 두가지 경우로부터 얻어진 각 추정량의 정도를 알아보기 위하여 각 추정량의 공분산행렬을 이 용하여 서로 비교하여 보았다. 각 추정량의 분산비들을 이용하여 일반적으로 일반화 혼합회귀추정량이 베이지안 회귀추정량들보다 비교적 작은 분산값을 가진다는 결론을 얻었다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1993.05a
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• pp.106-111
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• 1993

오늘날의 전력수급계획은 불확실성하에서의 다목적 의사결정과정으로 볼 수 있으며, 이러한 계획환경하에서는 하나의 최적해는 존재하지 않는다. 본 논문은 의사결정자가 여러 상충하는 목적들 사이의 최상의 계획안 또는 전략을 도출하기 위하여, 전략계획의 개념을 응용한 표준적인 전력수급계획체계를 제시하였으며, 분석모형으로서 다목적 전략평가모형 (MOST)을 개발하였다. 개발된 다목적 전략평가모형은 Trade-off 분석기법을 기초로 하고 있으며, 특히 C 언어로 프로그래밍 되어 있어서 Menu 방식에 의한 분석이 용이하다. 이 모형은 화면상에서의 속성간 Graphic 분석기능, Robust 계획안 및 옵션 도출기능, 위험도 및 계획안간 비교분석기능을 포함하고 있다.

• Communications for Statistical Applications and Methods
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• v.4 no.3
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• pp.753-763
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• 1997

컴퓨터의 발전에 따른 MCMC를 비동질적 포아송 과정에 이용하였다. 베이지안 추론에서 조건부 분포를 가지고 사후분포를 결정하는데 있어서의 계산 문제를 고려하였다. 특히 분포가 이중지수, 곰페르츠, 랄리, 감마, 그리고 검벨인 일반 순서통계량 모형에 대하여 깁스 샘플링과 메트로폴리스 알고리즘을 활용한 베이지안 계산과 모형선택을 제시하였다.

• Journal of Korea Water Resources Association
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• v.38 no.8 s.157
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• pp.631-643
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• 2005

The objective of this study is to perform hydraulic and numerical model experiments of the flows in circulation-water-pump(CWP) chambers of combined cycle power plants (CCPP) to be built and to suggest improvement plans if the flows might cause a serious problem on the operation of CWPs. Hydraulic model was constructed in a scale of 1 to 20 using acrylic sheets and a two dimensional numerical model used was RMA2. To evaluate results of Hydraulic and numerical model experiments, evaluation criteria of flow conditions in the intake canal and CWP chambers were determined. Vertical vorticities obtained from numerical simulations for the initial plan of CCPPs were qualitatively compared with results of hydraulic model experiments and the formation possibility of a large scale vortex, one of the flow evaluation criteria, was evaluated. The initial plan was found not to satisfy the flow evaluation. Nine improvement plans were devised and numerically simulated. Four alternative plans among nine improvement plans were selected and hydraulically experimented. On the ground of the results of hydraulic model experiments, a final improvement plan, one of four improvement plants, was suggested. When CWP chambers and intake canals were designed with spatial constraints, flow separating wall and guide walls were found to improve flow conditions in CWP chambers.

• The Korean Journal of Applied Statistics
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• v.15 no.2
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• pp.251-267
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• 2002

Self Organizing Maps(SOM) by Kohonen is very fast algorithm in neural networks. But it doesn't show sure rules of training results. In this paper, we introduce to Bayesian Learning for Self Organizing Maps(BLSOM) which combines self organizing maps with Bayesian learning. So it supports explanatory power of models and improves prediction. BLSOM has global optima anywhere but SOM has not. This is proved by experiment in this paper.

• The Korean Journal of Applied Statistics
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• v.27 no.6
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• pp.933-945
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• 2014

Bayesian spatiotemporal analysis is of considerable interest to epidemiological applications because health data is collected over space-time with complicated dependency structures. A basic concept in spatiotemporal modeling is introduced in this paper to analyze space-time disease data. The paper reviews a range of Bayesian spatiotemporal models and analyzes Hepatitis A data in Korea.

• The Korean Journal of Applied Statistics
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• v.26 no.5
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• pp.737-746
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• 2013

The Bayesian method can be applied successfully to the estimation of the censored regression model introduced by Tobin (1958). The Bayes estimates show improvements over the maximum likelihood estimate; however, the performance of the Bayesian interval estimation is questionable. In Bayesian paradigm, the prior distribution usually reflects personal beliefs about the parameters. Such subjective priors will typically yield interval estimators with poor frequentist properties; however, an objective noninformative often yields a Bayesian procedure with good frequentist properties. We examine the performance of frequentist properties of noninformative priors for the Tobit regression model.