• 응용통계연구
• /
• 제14권1호
• /
• pp.161-175
• /
• 2001

메타분석(Meta-analysis)은 서로 독립적으로 연구되어진 결과들을 전체적인 하나의 결과로 도출하기 위해 사용되어지는 통계적 방법이다. 이러한 통계적 방법을 설명할 모형으로는 선택모형(selection model)을 포함한 계층적 모형(hierarchical model)을 사용하며, 이러한 모형들은 베이지안 메타분석에 유용한 것으로 알려져 있다. 그러나, 메타분석의 자료들은 일반적으로 출판편의(publication bias)를 갖고 있으므로 이를 극복하고자 가중함수(weight function)를 이용하여 분포함수를 새롭게 정의하여 사용한다. 최근에 Silliman(1997)은 계층적 모형(hierarchical model)에 가중함수를 첨부한 계층적 선택모형(hierarchical selection model)을 정의하고 모수적 베이지안 방법을 제시하였다. 본 연구에서는 미관측된 연구효과에 디리슈레 과정 사전분포(Dirichlet process prior)를 적용한 준모수적 계층적 선택모형(semiparametric hierarchical selection models)을 소개한다. 여기서 제시된 준모수적 계층적 선택모형을 베이지안 방법으로 추정하기 위하여 마코프 연쇄 몬테칼로(Markov chain Monte Carlo)방법을 이용한다. 제시된 방법을 적용하기 위하여 실제 자료(Johnson, 1993)인 충치를 예방하기 위한 두 가지의 예방약의 효과에 대한 차이를 비교하기 위해 얻어진 12개의 연구를 이용하여 메타분석을 한다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.1343-1346
• /
• 2005

In the cold rolling mill, coil breakage that generated in rolling process makes the various types of troubles such as the degradation of productivity and the damage of equipment. Recent researches were done by the mechanical analysis such as the analysis of roll chattering or strip inclining and the prevention of breakage that detects the crack of coil. But they could cover some kind of breakages. The prediction of Coil breakage was very complicated and occurred rarely. We propose to build effective prediction modes for coil breakage in rolling process, based on data mining model. We proposed three prediction models for coil breakage: (1) decision tree based model, (2) regression based model and (3) neural network based model. To reduce model parameters, we selected important variables related to the occurrence of coil breakage from the attributes of coil setup by using the methods such as decision tree, variable selection and the choice of domain experts. We developed these prediction models and chose the best model among them using SEMMA process that proposed in SAS E-miner environment. We estimated model accuracy by scoring the prediction model with the posterior probability. We also have developed a software tool to analyze the data and generate the proposed prediction models either automatically and in a user-driven manner. It also has an effective visualization feature that is based on PCA (Principle Component Analysis).

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
• /
• pp.576-581
• /
• 1993

Grinding in the cement industry is a very energy-exacting process, therefore it is essential that these systems should operate with the highest possible efficiency. But, Cement grinding process is a complicated nonlinear system with large dead time, very noisy signal and many stochastic disturbances. So, it is difficult to develope mathematic process model. This paper presents correlation analysis of process variables and construction of experimental model for a ball mill grinding process.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2006년도 춘계학술대회 논문집
• /
• pp.329-332
• /
• 2006

$Conform^{TM}$, a continuous extrusion forming process can produce a variety of very long extruded products such as aluminum alloyed wires, strips and profiles, hollow sectioned tubes, coated wires used in the current forming industry. This process has some advantages like as superiority of pre-heating free, availability of high extrusion ratio and continuous forming without stroke limit. But it is still difficult to analyze the realistic model of the process. In this study the analysis using two-dimensional model of $Conform^{TM}$ process together with several parametric investigations on the heat transfer are carried out by FEA code DEFORM $^{TM}2D$. In spite of simple model the results of analysis shows a good guidance to design the real process.

• 상하수도학회지
• /
• 제27권5호
• /
• pp.555-560
• /
• 2013

A cost analysis method for pretreament processes of a large scale seawater desalination plant was considered using a cost estimation model, WaTER (Water Treatment Estimation Routine). This model is based on cost functions of U.S. EPA to conduct economic analysis of water treatment facilities. A virtual seawater desalination plant which has pretreatment production capacity of $100,000m^3$ per day was chosen as a model plant. Dual media filtration and microfiltration systems were compared as pretreatment process, and the following reverse osmosis process was modeled. As a result, microfiltration showed a price competitiveness in condition of operating with reverse osmosis process by reducing the loads of water treatment and membrane cleaning despite it's high annual cost.

• International Journal of Reliability and Applications
• /
• 제14권2호
• /
• pp.55-70
• /
• 2013

This paper deals with the Bayesian analysis of the failure data of a repairable mechanical system subject to minimal repairs and periodic overhauls. The effect of overhauls on the reliability of the system is modeled by a proportional age reduction model and the failure process between two successive overhauls is assumed to be 2-parameter Engelhardt-Bain process (2-EBP). Power Law Process (PLP) model has a disadvantage which 2-EBP can overcome. On the basis of the observed data and of a number of suitable prior densities, point and interval estimation of model parameters, as well as quantities of relevant interest are found. Also hypothesis tests on the effectiveness of performed overhauls have been developed using Bayes factor. Sensitivity analysis of improvement parameter is carried out. Finally, a numerical application is used to illustrate the proposed method.

• 한국경영과학회지
• /
• 제39권4호
• /
• pp.1-17
• /
• 2014

The functions of stocking and releasing in logistics center consist of three major procedure such as receiving, shipping and stock managements. Each process includes various sub-processes which are complicatedly connected with each other. Furthermore, lots of operators execute various tasks in the different sub-processes, simultaneously. It makes difficult to standardize, monitor, and analyze the processes. This paper proposed the quantitative methodology using process mining approach to discover and analyze receiving and shipping processes. For this purpose, the PDA operation log data is analyzed to build a realistic process model. The deduced model has been compared with official process model. In addition, task assignment and social networks analysises are carried out by utilizing process mining tools. Also, it has been proposed how to improve the processes with the analytical simulation model based on the results of process mining.

• 한국기계가공학회지
• /
• 제16권6호
• /
• pp.139-145
• /
• 2017

It is necessary to analyze the exact contact position and contact stress of the wheel-rail in order to predict damage to the wheel and rail. This study presents a wheel-rail contact analysis model that considers the deformation of the axle. When a wheel-rail contact analysis is performed using a full three-dimensional model of the wheelset and rail, the analytical model becomes very inefficient due to the increase in analysis time and cost. Therefore, modeling the element-coupling model of the wheel and rail as a three-dimensional element and the axle as a one-dimensional element is proposed. The wheel-rail contact characteristics in the proposed analysis model for straight and curved lines were analyzed and compared with the conventional three-dimensional analysis model. Considering the accuracy of the analysis results and time, the result shows that the proposed analytical model has almost the same accuracy as a full three-dimensional model, but the computational effort is significantly reduced.

• 소성∙가공
• /
• 제13권8호
• /
• pp.671-677
• /
• 2004

For the large reduction in tube cross section, the tube drawing process is usually performed by two successive passes, so called first drawing and second drawing. In multi-pass drawing process, the reduction balance is important to prevent drawing cracks. Therefore in this study, the model for uniform reduction distribution in two-pass drawing process has been developed on the basis of cross sectional variation of drawn tube. For the given product geometry the model provides optimal diameter and thickness that can evenly distribute drawing reductions. The capability of model is well confirmed by finite element analysis of tube drawing process. Criteria curves at various limit strains to determine whether the drawn tube would fail during drawing process are also proposed by using newly developed model.

• 정보처리학회논문지D
• /
• 제16D권5호
• /
• pp.791-800
• /
• 2009

최근 서비스 지향 아키텍처 (Service Oriented Architecture SOA) 기반의 애플리케이션 개발에 맞게 비즈니스 프로세스의 유연성을 확보하고 재사용을 증진시키기 위하여 비즈니스 프로세스 패밀리 모델 (Business Process Family Model: BPFM)이 제시되었다. BPFM은 소프트웨어 프로덕트 라인 방법의 가변성 분석 기법을 사용하여 비즈니스 프로세스 군 (family)에서 나타날 수 있는 가변성을 분석하여 이를 명시적으로 표현하고 있는 모델이다. BPFM으로부터 여러 개의 비즈니스 프로세스 모델 (Business Process Model: BPM)을 개발하기 위해서는 가변성 결정 및 가지치기(Decision and Pruning) 과정을 거쳐야 한다. 이 때 가변성 사이에는 서로 협력적 또는 배타적인 관계를 가질 수 있고 이는 가변성 결정과 가지치기에 영향을 미치게 되는데, 현재 제시된 BPFM에는 이러한 바인딩 정보에 대해서 고려하지 않고 있다. 본 논문에서는 비즈니스 프로세스 군에서 식별될 수 있는 가변성들 사이의 의존관계 유형을 분석하고 이러한 가변성 정보를 독립된 의존관계 분석모델로 표현하는 방법을 제시한다. 또한 추출된 모델을 기반으로 하나의 가변성 결정으로부터 영향을 받는 다른 가변성들을 추적하여 선결정 처리 할 수 있는 방법을 제공한다. 본 방법을 이용함으로써 가변성 결정회수를 줄일 수 있고, 또한 잘못된 가변성 결정으로 인한 BPM의 기능 불일치를 해소할 수 있음을 사례연구를 통해 보인다.