575 research outputs found
Data-Driven Fault Detection and Reasoning for Industrial Monitoring
This open access book assesses the potential of data-driven methods in industrial process monitoring engineering. The process modeling, fault detection, classification, isolation, and reasoning are studied in detail. These methods can be used to improve the safety and reliability of industrial processes. Fault diagnosis, including fault detection and reasoning, has attracted engineers and scientists from various fields such as control, machinery, mathematics, and automation engineering. Combining the diagnosis algorithms and application cases, this book establishes a basic framework for this topic and implements various statistical analysis methods for process monitoring. This book is intended for senior undergraduate and graduate students who are interested in fault diagnosis technology, researchers investigating automation and industrial security, professional practitioners and engineers working on engineering modeling and data processing applications. This is an open access book
Data-Driven Fault Detection and Reasoning for Industrial Monitoring
This open access book assesses the potential of data-driven methods in industrial process monitoring engineering. The process modeling, fault detection, classification, isolation, and reasoning are studied in detail. These methods can be used to improve the safety and reliability of industrial processes. Fault diagnosis, including fault detection and reasoning, has attracted engineers and scientists from various fields such as control, machinery, mathematics, and automation engineering. Combining the diagnosis algorithms and application cases, this book establishes a basic framework for this topic and implements various statistical analysis methods for process monitoring. This book is intended for senior undergraduate and graduate students who are interested in fault diagnosis technology, researchers investigating automation and industrial security, professional practitioners and engineers working on engineering modeling and data processing applications. This is an open access book
Unknown Health States Recognition With Collective Decision Based Deep Learning Networks In Predictive Maintenance Applications
At present, decision making solutions developed based on deep learning (DL)
models have received extensive attention in predictive maintenance (PM)
applications along with the rapid improvement of computing power. Relying on
the superior properties of shared weights and spatial pooling, Convolutional
Neural Network (CNN) can learn effective representations of health states from
industrial data. Many developed CNN-based schemes, such as advanced CNNs that
introduce residual learning and multi-scale learning, have shown good
performance in health state recognition tasks under the assumption that all the
classes are known. However, these schemes have no ability to deal with new
abnormal samples that belong to state classes not part of the training set. In
this paper, a collective decision framework for different CNNs is proposed. It
is based on a One-vs-Rest network (OVRN) to simultaneously achieve
classification of known and unknown health states. OVRN learn state-specific
discriminative features and enhance the ability to reject new abnormal samples
incorporated to different CNNs. According to the validation results on the
public dataset of Tennessee Eastman Process (TEP), the proposed CNN-based
decision schemes incorporating OVRN have outstanding recognition ability for
samples of unknown heath states, while maintaining satisfactory accuracy on
known states. The results show that the new DL framework outperforms
conventional CNNs, and the one based on residual and multi-scale learning has
the best overall performance
A Review of Kernel Methods for Feature Extraction in Nonlinear Process Monitoring
Kernel methods are a class of learning machines for the fast recognition of nonlinear patterns in any data set. In this paper, the applications of kernel methods for feature extraction in industrial process monitoring are systematically reviewed. First, we describe the reasons for using kernel methods and contextualize them among other machine learning tools. Second, by reviewing a total of 230 papers, this work has identified 12 major issues surrounding the use of kernel methods for nonlinear feature extraction. Each issue was discussed as to why they are important and how they were addressed through the years by many researchers. We also present a breakdown of the commonly used kernel functions, parameter selection routes, and case studies. Lastly, this review provides an outlook into the future of kernel-based process monitoring, which can hopefully instigate more advanced yet practical solutions in the process industries
๋งค๊ฐ๋ถํฌ๊ทผ์ฌ๋ฅผ ํตํ ๊ณต์ ์์คํ ๊ณตํ์์์ ํ๋ฅ ๊ธฐ๊ณํ์ต ์ ๊ทผ๋ฒ
ํ์๋
ผ๋ฌธ(๋ฐ์ฌ) -- ์์ธ๋ํ๊ต๋ํ์ : ๊ณต๊ณผ๋ํ ํํ์๋ฌผ๊ณตํ๋ถ, 2021.8. ์ด์ข
๋ฏผ.With the rapid development of measurement technology, higher quality and vast amounts of process data become available. Nevertheless, process data are โscarceโ in many cases as they are sampled only at certain operating conditions while the dimensionality of the system is large. Furthermore, the process data are inherently stochastic due to the internal characteristics of the system or the measurement noises. For this reason, uncertainty is inevitable in process systems, and estimating it becomes a crucial part of engineering tasks as the prediction errors can lead to misguided decisions and cause severe casualties or economic losses. A popular approach to this is applying probabilistic inference techniques that can model the uncertainty in terms of probability. However, most of the existing probabilistic inference techniques are based on recursive sampling, which makes it difficult to use them for industrial applications that require processing a high-dimensional and massive amount of data. To address such an issue, this thesis proposes probabilistic machine learning approaches based on parametric distribution approximation, which can model the uncertainty of the system and circumvent the computational complexity as well. The proposed approach is applied for three major process engineering tasks: process monitoring, system modeling, and process design.
First, a process monitoring framework is proposed that utilizes a probabilistic classifier for fault classification. To enhance the accuracy of the classifier and reduce the computational cost for its training, a feature extraction method called probabilistic manifold learning is developed and applied to the process data ahead of the fault classification. We demonstrate that this manifold approximation process not only reduces the dimensionality of the data but also casts the data into a clustered structure, making the classifier have a low dependency on the type and dimension of the data. By exploiting this property, non-metric information (e.g., fault labels) of the data is effectively incorporated and the diagnosis performance is drastically improved.
Second, a probabilistic modeling approach based on Bayesian neural networks is proposed. The parameters of deep neural networks are transformed into Gaussian distributions and trained using variational inference. The redundancy of the parameter is autonomously inferred during the model training, and insignificant parameters are eliminated a posteriori. Through a verification study, we demonstrate that the proposed approach can not only produce high-fidelity models that describe the stochastic behaviors of the system but also produce the optimal model structure.
Finally, a novel process design framework is proposed based on reinforcement learning. Unlike the conventional optimization methods that recursively evaluate the objective function to find an optimal value, the proposed method approximates the objective function surface by parametric probabilistic distributions. This allows learning the continuous action policy without introducing any cumbersome discretization process. Moreover, the probabilistic policy gives means for effective control of the exploration and exploitation rates according to the certainty information. We demonstrate that the proposed framework can learn process design heuristics during the solution process and use them to solve similar design problems.๊ณ์ธก๊ธฐ์ ์ ๋ฐ๋ฌ๋ก ์์ง์, ๊ทธ๋ฆฌ๊ณ ๋ฐฉ๋ํ ์์ ๊ณต์ ๋ฐ์ดํฐ์ ์ทจ๋์ด ๊ฐ๋ฅํด์ก๋ค. ๊ทธ๋ฌ๋ ๋ง์ ๊ฒฝ์ฐ ์์คํ
์ฐจ์์ ํฌ๊ธฐ์ ๋นํด์ ์ผ๋ถ ์ด์ ์กฐ๊ฑด์ ๊ณต์ ๋ฐ์ดํฐ๋ง์ด ์ทจ๋๋๊ธฐ ๋๋ฌธ์, ๊ณต์ ๋ฐ์ดํฐ๋ โํฌ์โํ๊ฒ ๋๋ค. ๋ฟ๋ง ์๋๋ผ, ๊ณต์ ๋ฐ์ดํฐ๋ ์์คํ
๊ฑฐ๋ ์์ฒด์ ๋๋ถ์ด ๊ณ์ธก์์ ๋ฐ์ํ๋ ๋
ธ์ด์ฆ๋ก ์ธํ ๋ณธ์ง์ ์ธ ํ๋ฅ ์ ๊ฑฐ๋์ ๋ณด์ธ๋ค. ๋ฐ๋ผ์ ์์คํ
์ ์์ธก๋ชจ๋ธ์ ์์ธก ๊ฐ์ ๋ํ ๋ถํ์ค์ฑ์ ์ ๋์ ์ผ๋ก ๊ธฐ์ ํ๋ ๊ฒ์ด ์๊ตฌ๋๋ฉฐ, ์ด๋ฅผ ํตํด ์ค์ง์ ์๋ฐฉํ๊ณ ์ ์ฌ์ ์ธ๋ช
ํผํด์ ๊ฒฝ์ ์ ์์ค์ ๋ฐฉ์งํ ์ ์๋ค. ์ด์ ๋ํ ๋ณดํธ์ ์ธ ์ ๊ทผ๋ฒ์ ํ๋ฅ ์ถ์ ๊ธฐ๋ฒ์ ์ฌ์ฉํ์ฌ ์ด๋ฌํ ๋ถํ์ค์ฑ์ ์ ๋ํ ํ๋ ๊ฒ์ด๋, ํ์กดํ๋ ์ถ์ ๊ธฐ๋ฒ๋ค์ ์ฌ๊ท์ ์ํ๋ง์ ์์กดํ๋ ํน์ฑ์ ๊ณ ์ฐจ์์ด๋ฉด์๋ ๋ค๋์ธ ๊ณต์ ๋ฐ์ดํฐ์ ์ ์ฉํ๊ธฐ ์ด๋ ต๋ค๋ ๊ทผ๋ณธ์ ์ธ ํ๊ณ๋ฅผ ๊ฐ์ง๋ค. ๋ณธ ํ์๋
ผ๋ฌธ์์๋ ๋งค๊ฐ๋ถํฌ๊ทผ์ฌ์ ๊ธฐ๋ฐํ ํ๋ฅ ๊ธฐ๊ณํ์ต์ ์ ์ฉํ์ฌ ์์คํ
์ ๋ด์ฌ๋ ๋ถํ์ค์ฑ์ ๋ชจ๋ธ๋งํ๋ฉด์๋ ๋์์ ๊ณ์ฐ ํจ์จ์ ์ธ ์ ๊ทผ ๋ฐฉ๋ฒ์ ์ ์ํ์๋ค.
๋จผ์ , ๊ณต์ ์ ๋ชจ๋ํฐ๋ง์ ์์ด ๊ฐ์ฐ์์ ํผํฉ ๋ชจ๋ธ (Gaussian mixture model)์ ๋ถ๋ฅ์๋ก ์ฌ์ฉํ๋ ํ๋ฅ ์ ๊ฒฐํจ ๋ถ๋ฅ ํ๋ ์์ํฌ๊ฐ ์ ์๋์๋ค. ์ด๋ ๋ถ๋ฅ์์ ํ์ต์์์ ๊ณ์ฐ ๋ณต์ก๋๋ฅผ ์ค์ด๊ธฐ ์ํ์ฌ ๋ฐ์ดํฐ๋ฅผ ์ ์ฐจ์์ผ๋ก ํฌ์์ํค๋๋ฐ, ์ด๋ฅผ ์ํ ํ๋ฅ ์ ๋ค์์ฒด ํ์ต (probabilistic manifold learn-ing) ๋ฐฉ๋ฒ์ด ์ ์๋์๋ค. ์ ์ํ๋ ๋ฐฉ๋ฒ์ ๋ฐ์ดํฐ์ ๋ค์์ฒด (manifold)๋ฅผ ๊ทผ์ฌํ์ฌ ๋ฐ์ดํฐ ํฌ์ธํธ ์ฌ์ด์ ์๋ณ ์ฐ๋ (pairwise likelihood)๋ฅผ ๋ณด์กดํ๋ ํฌ์๋ฒ์ด ์ฌ์ฉ๋๋ค. ์ด๋ฅผ ํตํ์ฌ ๋ฐ์ดํฐ์ ์ข
๋ฅ์ ์ฐจ์์ ์์กด๋๊ฐ ๋ฎ์ ์ง๋จ ๊ฒฐ๊ณผ๋ฅผ ์ป์๊ณผ ๋์์ ๋ฐ์ดํฐ ๋ ์ด๋ธ๊ณผ ๊ฐ์ ๋น๊ฑฐ๋ฆฌ์ (non-metric) ์ ๋ณด๋ฅผ ํจ์จ์ ์ผ๋ก ์ฌ์ฉํ์ฌ ๊ฒฐํจ ์ง๋จ ๋ฅ๋ ฅ์ ํฅ์์ํฌ ์ ์์์ ๋ณด์๋ค.
๋์งธ๋ก, ๋ฒ ์ด์ง์ ์ฌ์ธต ์ ๊ฒฝ๋ง(Bayesian deep neural networks)์ ์ฌ์ฉํ ๊ณต์ ์ ํ๋ฅ ์ ๋ชจ๋ธ๋ง ๋ฐฉ๋ฒ๋ก ์ด ์ ์๋์๋ค. ์ ๊ฒฝ๋ง์ ๊ฐ ๋งค๊ฐ๋ณ์๋ ๊ฐ์ฐ์ค ๋ถํฌ๋ก ์นํ๋๋ฉฐ, ๋ณ๋ถ์ถ๋ก (variational inference)์ ํตํ์ฌ ๊ณ์ฐ ํจ์จ์ ์ธ ํ๋ จ์ด ์งํ๋๋ค. ํ๋ จ์ด ๋๋ ํ ํ๋ผ๋ฏธํฐ์ ์ ํจ์ฑ์ ์ธก์ ํ์ฌ ๋ถํ์ํ ๋งค๊ฐ๋ณ์๋ฅผ ์๊ฑฐํ๋ ์ฌํ ๋ชจ๋ธ ์์ถ ๋ฐฉ๋ฒ์ด ์ฌ์ฉ๋์๋ค. ๋ฐ๋์ฒด ๊ณต์ ์ ๋ํ ์ฌ๋ก ์ฐ๊ตฌ๋ ์ ์ํ๋ ๋ฐฉ๋ฒ์ด ๊ณต์ ์ ๋ณต์กํ ๊ฑฐ๋์ ํจ๊ณผ์ ์ผ๋ก ๋ชจ๋ธ๋ง ํ ๋ฟ๋ง ์๋๋ผ ๋ชจ๋ธ์ ์ต์ ๊ตฌ์กฐ๋ฅผ ๋์ถํ ์ ์์์ ๋ณด์ฌ์ค๋ค.
๋ง์ง๋ง์ผ๋ก, ๋ถํฌํ ์ฌ์ธต ์ ๊ฒฝ๋ง์ ์ฌ์ฉํ ๊ฐํํ์ต์ ๊ธฐ๋ฐ์ผ๋ก ํ ํ๋ฅ ์ ๊ณต์ ์ค๊ณ ํ๋ ์์ํฌ๊ฐ ์ ์๋์๋ค. ์ต์ ์น๋ฅผ ์ฐพ๊ธฐ ์ํด ์ฌ๊ท์ ์ผ๋ก ๋ชฉ์ ํจ์ ๊ฐ์ ํ๊ฐํ๋ ๊ธฐ์กด์ ์ต์ ํ ๋ฐฉ๋ฒ๋ก ๊ณผ ๋ฌ๋ฆฌ, ๋ชฉ์ ํจ์ ๊ณก๋ฉด (objective function surface)์ ๋งค๊ฐํ ๋ ํ๋ฅ ๋ถํฌ๋ก ๊ทผ์ฌํ๋ ์ ๊ทผ๋ฒ์ด ์ ์๋์๋ค. ์ด๋ฅผ ๊ธฐ๋ฐ์ผ๋ก ์ด์ฐํ (discretization)๋ฅผ ์ฌ์ฉํ์ง ์๊ณ ์ฐ์์ ํ๋ ์ ์ฑ
์ ํ์ตํ๋ฉฐ, ํ์ค์ฑ (certainty)์ ๊ธฐ๋ฐํ ํ์ (exploration) ๋ฐ ํ์ฉ (exploi-tation) ๋น์จ์ ์ ์ด๊ฐ ํจ์จ์ ์ผ๋ก ์ด๋ฃจ์ด์ง๋ค. ์ฌ๋ก ์ฐ๊ตฌ ๊ฒฐ๊ณผ๋ ๊ณต์ ์ ์ค๊ณ์ ๋ํ ๊ฒฝํ์ง์ (heuristic)์ ํ์ตํ๊ณ ์ ์ฌํ ์ค๊ณ ๋ฌธ์ ์ ํด๋ฅผ ๊ตฌํ๋ ๋ฐ ์ด์ฉํ ์ ์์์ ๋ณด์ฌ์ค๋ค.Chapter 1 Introduction 1
1.1. Motivation 1
1.2. Outline of the thesis 5
Chapter 2 Backgrounds and preliminaries 9
2.1. Bayesian inference 9
2.2. Monte Carlo 10
2.3. Kullback-Leibler divergence 11
2.4. Variational inference 12
2.5. Riemannian manifold 13
2.6. Finite extended-pseudo-metric space 16
2.7. Reinforcement learning 16
2.8. Directed graph 19
Chapter 3 Process monitoring and fault classification with probabilistic manifold learning 20
3.1. Introduction 20
3.2. Methods 25
3.2.1. Uniform manifold approximation 27
3.2.2. Clusterization 28
3.2.3. Projection 31
3.2.4. Mapping of unknown data query 32
3.2.5. Inference 33
3.3. Verification study 38
3.3.1. Dataset description 38
3.3.2. Experimental setup 40
3.3.3. Process monitoring 43
3.3.4. Projection characteristics 47
3.3.5. Fault diagnosis 50
3.3.6. Computational Aspects 56
Chapter 4 Process system modeling with Bayesian neural networks 59
4.1. Introduction 59
4.2. Methods 63
4.2.1. Long Short-Term Memory (LSTM) 63
4.2.2. Bayesian LSTM (BLSTM) 66
4.3. Verification study 68
4.3.1. System description 68
4.3.2. Estimation of the plasma variables 71
4.3.3. Dataset description 72
4.3.4. Experimental setup 72
4.3.5. Weight regularization during training 78
4.3.6. Modeling complex behaviors of the system 80
4.3.7. Uncertainty quantification and model compression 85
Chapter 5 Process design based on reinforcement learning with distributional actor-critic networks 89
5.1. Introduction 89
5.2. Methods 93
5.2.1. Flowsheet hashing 93
5.2.2. Behavioral cloning 99
5.2.3. Neural Monte Carlo tree search (N-MCTS) 100
5.2.4. Distributional actor-critic networks (DACN) 105
5.2.5. Action masking 110
5.3. Verification study 110
5.3.1. System description 110
5.3.2. Experimental setup 111
5.3.3. Result and discussions 115
Chapter 6 Concluding remarks 120
6.1. Summary of the contributions 120
6.2. Future works 122
Appendix 125
A.1. Proof of Lemma 1 125
A.2. Performance indices for dimension reduction 127
A.3. Model equations for process units 130
Bibliography 132
์ด ๋ก 149๋ฐ
Recommended from our members
Fault Classification of Nonlinear Small Sample Data through Feature Sub-Space Neighbor Vote
The fault classification of a small sample of high dimension is challenging, especially for a nonlinear and non-Gaussian manufacturing process. In this paper, a similarity-based feature selection and sub-space neighbor vote method is proposed to solve this problem. To capture the dynamics, nonlinearity, and non-Gaussianity in the irregular time series data, high order spectral features, and fractal dimension features are extracted, selected, and stacked in a regular matrix. To address the problem of a small sample, all labeled fault data are used for similarity decisions for a specific fault type. The distances between the new data and all fault types are calculated in their feature subspaces. The new data are classified to the nearest fault type by majority probability voting of the distances. Meanwhile, the selected features, from respective measured variables, indicate the cause of the fault. The proposed method is evaluated on a publicly available benchmark of a real semiconductor etching dataset. It is demonstrated that by using the high order spectral features and fractal dimensionality features, the proposed method can achieve more than 84% fault recognition accuracy. The resulting feature subspace can be used to match any new fault data to the fingerprint feature subspace of each fault type, and hence can pinpoint the root cause of a fault in a manufacturing process
๋ง๋ฅด์ฝํ ๋๋ค ํ๋ ํ์ต ๋ฐ ์ถ๋ก ๊ณผ ๊ทธ๋ํ ๋ผ์๋ฅผ ํ์ฉํ ๊ณต์ ์ด์ ๊ฐ์ง ๋ฐ ์ง๋จ ๋ฐฉ๋ฒ๋ก
ํ์๋
ผ๋ฌธ (๋ฐ์ฌ)-- ์์ธ๋ํ๊ต ๋ํ์ : ๊ณต๊ณผ๋ํ ํํ์๋ฌผ๊ณตํ๋ถ, 2019. 2. ์ด์๋ณด.Fault detection and diagnosis (FDD) is an essential part of safe plant operation. Fault detection refers to the process of detecting the occurrence of a fault quickly and accurately, and representative methods include the use of principal component analysis (PCA), and autoencoders (AE). Fault diagnosis is the process of isolating the root cause node of the fault, then determining the fault propagation path to identify the characteristic of the fault. Among the various methods, data-driven methods are the most widely-used, due to their applicability and good performance compared to analytical and knowledge-based methods. Although many studies have been conducted regarding FDD, no methodology for conducting every step of FDD exists, where the fault is effectively detected and diagnosed. Moreover, existing methods have limited applicability and show limited performance. Previous fault detection methods show loss of variable characteristics in dimensionality reduction methods and have large computational loads, leading to poor performance for complex faults. Likewise, preceding fault diagnosis methods show inaccurate fault isolation results, and biased fault propagation path analysis as a consequence of implementing knowledge-based characteristics for construction of digraphs of process variable relationships. Thus a comprehensive methodology for FDD which shows good performance for complex faults and variable relationships, is required.
In this study, an efficient and effective comprehensive FDD methodology based on Markov random fields (MRF) modelling is proposed. MRFs provide an effective means for modelling complex variable relationships, and allows efficient computation of marginal probability of the process variables, leading to good performance regarding FDD.
First, a fault detection framework for process variables, integrating the MRF modelling and structure learning with iterative graphical lasso is proposed. Graphical lasso is an algorithm for learning the structure of MRFs, and is applicable to large variable sets since it approximates the MRF structure by assuming the relationships between variables to be Gaussian. By iteratively applying the graphical lasso to monitored variables, the variable set is subdivided into smaller groups, and consequently the computational cost of MRF inference is mitigated allowing efficient fault detection. After variable groups are obtained through iterative graphical lasso, they are subject to the MRF monitoring framework that is proposed in this work. The framework obtains the monitoring statistics by calculating the probability density of the variable groups through kernel density estimation, and the monitoring limits are obtained separately for each group by using a false alarm rate of 5%.
Second, a fault isolation and propagation path analysis methodology is proposed, where the conditional marginal probability of each variable is computed via inference, then is used to calculate the conditional contribution of individual variables during the occurrence of a fault. Using the kernel belief propagation (KBP) algorithm, which is an algorithm for learning and inferencing MRFs comprising continuous variables, the parameters of MRF are trained using normal process data, then the individual conditional contribution of each variable is calculated for every sample of the fault process data. By analyzing the magnitude and reaction speed of the conditional contribution of individual variables, the root fault node can be isolated and the fault propagation path can be determined effectively.
Finally, the proposed methodology is verified by applying it to the well-known Tennessee Eastman process (TEP) model. Since the TEP has been used as a benchmark process over the past years for verifying various FDD methods, it serves the purpose of performance comparison. Also, since it consists of multiple units and has complex variable relationships such as recycle loops, it is suitable for verifying the performance of the proposed methodology. Application results show that the proposed methodology performs better compared to state-of-the-art FDD algorithms, in terms of both fault detection and diagnosis. Fault detection results showed that all 28 faults designed inside the TEP model were detected with a fault detection accuracy of over 95%, which is higher than any other previously proposed fault detection method. Also, the method showed good fault isolation and propagation path analysis results, where the root-cause node for every fault was detected correctly, and the characteristics of the initiated faults were identified through fault propagation path analysis.๊ณต์ ์ด์์ ๊ฐ์ง ๋ฐ ์ง๋จ ์์คํ
์ ์์ ํ ๊ณต์ ์ด์์ ํ์์ ์ธ ๋ถ๋ถ์ด๋ค. ์ด์ ๊ฐ์ง๋ ์ด์์ด ๋ฐ์ํ์ ๊ฒฝ์ฐ ์ฆ๊ฐ์ ์ผ๋ก ์ด๋ฅผ ์ ํํ๊ฒ ๊ฐ์งํ๋ ํ๋ก์ธ์ค๋ฅผ ์๋ฏธํ๋ฉฐ, ๋ํ์ ์ธ ๋ฐฉ๋ฒ์ผ๋ก๋ ์ฃผ์ฑ๋ถ ๋ถ์ ๋ฐ ์คํ ์ธ์ฝ๋๋ฅผ ํ์ฉํ ๊ฐ์ง ๋ฐฉ๋ฒ๋ก ์ด ์๋ค. ์ด์ ์ง๋จ์ ๊ฒฐํจ์ ๊ทผ๋ณธ ์์ธ์ด ๋๋ ๋
ธ๋๋ฅผ ๊ฒฉ๋ฆฌํ๊ณ , ์ด์์ ์ ํ ๊ฒฝ๋ก๋ฅผ ํ์งํ์ฌ ์ด์์ ํน์ฑ์ ์๋ณํ๋ ํ๋ก์ธ์ค์ด๋ค. ๊ณต์ ์ด์์ ๊ฐ์ง ๋ฐ ์ง๋จ ๋ฐฉ๋ฒ๋ก ์๋ ๋ชจ๋ธ ๋ถ์ ๋ฐฉ๋ฒ๋ก , ์ง์ ๊ธฐ๋ฐ ๋ฐฉ๋ฒ๋ก ๋ฑ์ ๋ค์ํ ๋ฐฉ๋ฒ๋ก ์ด ์์ง๋ง, ๊ณต์ ์ ๋ํ ์ ์ฉ ๊ฐ๋ฅ์ฑ๊ณผ ์ฑ๋ฅ ์ธก๋ฉด์์ ๊ฐ์ฅ ์ ์ฉํ๋ค๊ณ ์๋ ค์ ธ ์๋ ๋ฐ์ดํฐ ๊ธฐ๋ฐ ๋ฐฉ๋ฒ๋ก ์ด ๋๋ฆฌ ํ์ฉ๋๊ณ ์๋ค. ๊ณต์ ์ด์์ ๊ฐ์ง ๋ฐ ์ง๋จ์ ๋ํ ๋ฐ์ดํฐ ๊ธฐ๋ฐ ๋ฐฉ๋ฒ๋ก ์ ๋ค๋ฐฉ๋ฉด์ผ๋ก ์ฐ๊ตฌ๋์ด ์์ง๋ง, ์ด์ ๊ฐ์ง ๋ฐ ์ง๋จ์ ๋ชจ๋ ํจ๊ณผ์ ์ผ๋ก ์ํํ ์ ์๋ ๋ฐฉ๋ฒ๋ก ์ ์์์ ๋ถ๊ณผํ๋ฉฐ, ์กด์ฌํ๊ณ ์๋ ๋ฐฉ๋ฒ๋ก ๋ค ์ญ์ ๋ ๋ถ์ผ ๋ชจ๋์์ ์ข์ ์ฑ๋ฅ์ ๋ณด์ฌ์ฃผ๊ณ ์๋ ๊ฒฝ์ฐ๋ ์๋ค. ์ด๋ ๊ธฐ์กด ๋ฐฉ๋ฒ๋ก ๋ค์ ์ ์ฉ ๊ฐ๋ฅ์ฑ์ด ์ ํ๋์ด ์์ผ๋ฉฐ ๊ณต์ ์ ์ ์ฉ์ ์ ํ๋ ์ฑ๋ฅ์ ๋ณด์ฌ์ฃผ๊ธฐ ๋๋ฌธ์ด๋ค. ์ด์ ๊ฐ์ง์ ๊ฒฝ์ฐ, ๋์ฉ๋์ ๋ฐ์ดํฐ๋ฅผ ์ฒ๋ฆฌํ ๋ ๋ฐ์ํ๋ ๊ณผ๋ถํ๋ก ์ธํ ๊ฐ์ง ๋ฅ๋ ฅ์ ์ ํ, ์ฐจ์ ์ถ์ ๋ฐฉ๋ฒ๋ก ๋ค์ ์ฌ์ฉํ ์ ์ด์ ๋ฐ๋ฅธ ๋ณ์ ํน์ฑ ๋ฐ์์ ๋ถ์ ํ์ฑ, ๊ทธ๋ฆฌ๊ณ ์ถ์๋ ์ฐจ์์์์ ๊ณ์ฐ์ผ๋ก ์ธํ์ฌ ๋ณตํฉ์ ์ธ ํํ์ ์ด์์ ๊ฐ์งํด ๋ด์ง ๋ชปํ๋ ๋ฌธ์ ๋ฑ์ด ์๋ค. ์ด์ ์ง๋จ์ ๊ฒฝ์ฐ ์ด์์ ์์ธ์ด ๋๋ ๋
ธ๋์ ๊ฒฉ๋ฆฌ ๋ฐ ์ด์ ์ ํ ๊ฒฝ๋ก์ ๋ํ ๋ถ์์ด ๋ถ์ ํํ ๊ฒฝ์ฐ๊ฐ ๋ง์๋ฐ, ์ด๋ ์ฐจ์ ์ถ์๋ก ์ธํ์ฌ ๊ณต์ ๋ณ์์ ํน์ฑ์ด ์์ค๋๋ ์ฑ์ง์ด ์๊ณ , ๋ฐฉํฅ์ฑ ๊ทธ๋ํ๋ฅผ ํ์ฉํ ์ ๊ณต์ ์ ๋ํ ์ ํ ์ง์์ ์ ์ฉํจ์ผ๋ก์จ ํธํฅ๋ ์ด์ ์ง๋จ ๊ฒฐ๊ณผ๊ฐ ๋ํ๋๋ ๊ฒฝ์ฐ๋ค์ด ๋ฐ์ํ๊ธฐ ๋๋ฌธ์ด๋ค. ๊ธฐ์กด ๋ฐฉ๋ฒ๋ก ๋ค์ ๋ํ ์ด๋ฌํ ํ๊ณ์ ๋ค์ ๊ณ ๋ คํด ๋ดค์๋, ๋ณ์ ๊ฐ๊ฐ์ ํน์ฑ์ด ์์ค๋์ง ์๋๋กํ์ฌ ํจ๊ณผ์ ์ผ๋ก ์ด์์ ๋ํ ๊ฐ์ง์ ์ง๋จ์ ๋ชจ๋ ์ํํด ๋ผ ์ ์์ผ๋ฉด์๋, ๊ณ์ฐ์์ ํจ์จ์ฑ์ ๊ฐ์ถ, ์ด์ ๊ฐ์ง ๋ฐ ์ง๋จ์ ๋ํ ํตํฉ๋ ๋ฐฉ๋ฒ๋ก ์ ๊ฐ๋ฐ์ด ์๊ธํ๋ค๊ณ ํ ์ ์๋ค.
๋ณธ ์ฐ๊ตฌ์์๋ ๋ง๋ฅด์ฝํ ๋๋ค ํ๋ ๋ชจ๋ธ๋ง๊ณผ ๊ทธ๋ํ ๋ผ์๋ฅผ ๊ธฐ๋ฐ์ผ๋กํ์ฌ, ์ด์์ ๋ํ ๊ฐ์ง ๋ฐ ์ง๋จ์ ๋ชจ๋ ์ํํด ๋ผ ์ ์๋ ํตํฉ์ ์ธ ๊ณต์ ๋ชจ๋ํฐ๋ง ๋ฐฉ๋ฒ๋ก ์ ์ ์ํ๋ค. ๋ง๋ฅด์ฝํ ๋๋ค ํ๋๋ ๋น์ ํ์ ์ด๊ณ ๋น์ ๊ท์ ์ธ ๋ณ์ ๊ด๊ณ๋ฅผ ํจ๊ณผ์ ์ผ๋ก ๋ชจ๋ธ๋งํ ์ ์๊ฒ ํด์ฃผ๊ณ , ์ด์ ๋ฐ์ ์ํฉ์์์ ๋ชจ๋ํฐ๋ง ํต๊ณ๊ฐ ๊ณ์ฐ์์ ๊ฐ ๋ณ์์ ํน์ฑ์ ๋ฐ์ํ์ฌ ํ๋ฅ ๊ณ์ฐ์ ํด ๋ผ ์ ์๊ธฐ ๋๋ฌธ์ ํจ๊ณผ์ ์ธ ์ด์ ๊ฐ์ง ๋ฐ ์ง๋จ ์๋จ์ด ๋๋ค. ๊ธฐ๋ณธ์ ์ผ๋ก ๋ง๋ฅด์ฝํ ๋๋ค ํ๋๋ ํ๋ฅ ๊ฐ ๊ณ์ฐ์์ ๋ถํ๊ฐ ํฌ์ง๋ง, ๋ณธ ์ฐ๊ตฌ์์๋ ๊ทธ๋ํ ๋ผ์ ๋ฐฉ๋ฒ๋ก ์ ์ถ๊ฐ์ ์ผ๋ก ํจ๊ป ํ์ฉํ์ฌ ๊ณ์ฐ ์์ ๋ถํ๋ฅผ ์ค์ด๊ณ ํจ์จ์ ์ผ๋ก ์ด์ ๊ฐ์ง ๋ฐ ์ง๋จ์ ํด๋ผ ์ ์๋๋ก ํ์๋ค. ๋ณธ ์ฐ๊ตฌ์์ ์ ์๋ ๋ด์ฉ๋ค์ ๋ค์๊ณผ ๊ฐ๋ค.
์ฒซ์งธ, ๊ณต์ ๋ณ์๋ฅผ ๋ง๋ฅด์ฝํ ๋๋ค ํ๋ ํํ๋ก ๋ชจ๋ธ๋งํ๊ณ , ๊ทธ๋ํ ๋ผ์๋ฅผ ํ์ฉํด ๋ง๋ฅด์ฝํ ๋๋ค ํ๋์ ๊ตฌ์กฐ๋ฅผ ์ป์ ์ ์๋ ๋ฐฉ๋ฒ๋ก ์ ์ ์ํ์๋ค. ๊ทธ๋ํ ๋ผ์๋ ๋ง๋ฅด์ฝํ ๋๋ค ํ๋์ ๊ตฌ์กฐ๋ฅผ ํ์
ํ๊ธฐ ์ํ ๋ฐฉ๋ฒ๋ก ์ธ๋ฐ, ๋ณ์ ๊ฐ์ ๊ด๊ณ๋ฅผ ๊ฐ์ฐ์ค ํจ์์ ํํ๋ก ๊ฐ์ ํ๊ธฐ ๋๋ฌธ์ ๋ค๋ณ์ ์์คํ
์์๋ ํจ์จ์ ์ผ๋ก ๊ทธ๋ํ ๊ตฌ์กฐ๋ฅผ ํ์
ํ ์ ์๋๋ก ํด์ค๋ค. ๋ณธ ์ฐ๊ตฌ์์๋ ๋ฐ๋ณต์ ๊ทธ๋ํ ๋ผ์๋ฅผ ์ ์ํ์ฌ ๋ชจ๋ ๊ณต์ ๋ณ์๋ค์ด ์๊ด๊ด๊ณ๊ฐ ๋์ ๋ณ์ ์ง๋จ์ผ๋ก ๋ฌถ์ผ ์ ์๋๋ก ํ์๋ค. ์ด๋ฅผ ํ์ฉํ๋ฉด ์ ์ฒด ๊ณต์ ๋ณ์ ์ง๋จ์ ๋ค์์ ์์ง๋จ์ผ๋ก ๋ถ๋ฅํ๊ณ ๊ฐ๊ฐ์ ๋ํ ๊ทธ๋ํ ๊ตฌ์กฐ๋ฅผ ํ์
ํ ์ ์๊ฒ ๋๋๋ฐ, ํฌ๊ฒ ๋ ๊ฐ์ง์ ํจ๊ณผ๋ฅผ ์ป์ ์ ์๋ค. ์ฐ์ ์ ์ผ๋ก ๋ง๋ฅด์ฝํ ๋๋ค ํ๋ ํ๋ฅ ๊ณ์ฐ์ ๋์์ด ๋๋ ๋ณ์์ ๊ฐ์๋ฅผ ์ค์ฌ์ค์ผ๋ก์จ ๊ณ์ฐ ๋ถํ๋ฅผ ์ค์ด๊ณ ํจ์จ์ ์ธ ์ด์ ๊ฐ์ง๊ฐ ์ด๋ฃจ์ด์ง ์ ์๋๋ก ํ๋ค. ๋ํ ์๊ด๊ด๊ณ๊ฐ ๋์ ์ง๋จ๋ผ๋ฆฌ ๋ฌถ์ฌ์ ๋ชจ๋ธ๋ง ๋ ๊ทธ๋ํ๋ฅผ ํ์ฉํ์ฌ ์ด์์ ์ง๋จ ๊ณผ์ ์์ ๊ณต์ ๋ณ์ ๊ฐ์ ๊ด๊ณ ํ์
๋ฐ ์ ํ ๊ฒฝ๋ก ๋ถ์์ ์ฉ์ดํ๋๋ก ํด์ค๋ค.
๋ ๋ฒ์งธ๋ก, ๋ง๋ฅด์ฝํ ๋๋ค ํ๋์ ํ๋ฅ ์ถ๋ก ์ ๊ธฐ๋ฐ์ผ๋ก ํ์ฌ ํจ๊ณผ์ ์ผ๋ก ์ด์ ๊ฐ์ง๊ฐ ์ด๋ฃจ์ด์ง ์ ์๋๋ก ํ๋ ๋ฐฉ๋ฒ๋ก ์ ์ ์ํ์๋ค. ๋ฐ๋ณต์ ๊ทธ๋ํ ๋ผ์๋ฅผ ํตํด ์ป์ด์ง ๋ค์์ ๋ณ์ ์์ง๋จ์ ๋ํ์ฌ ๊ฐ๊ฐ ํ๋ฅ ์ถ๋ก ์ ์ ์ฉํ์ฌ ์ด์ ๊ฐ์ง๋ฅผ ์งํํ๊ฒ ๋๋๋ฐ, ์ ์๋ ๋ฐฉ๋ฒ๋ก ์์๋ ์ปค๋ ๋ฐ๋ ์ถ์ ๋ฐฉ๋ฒ๋ก ์ ํ์ฉํ์๋ค. ์ ์ ๋ฐ์ดํฐ๋ฅผ ํ์ฉํ์ฌ ๊ฐ ๋ณ์๋ค์ ๋ํ ์ปค๋ ๋ฐ๋์ ๋์ญํญ์ ํ์ตํ๊ณ , ์ด์ ๋ฐ์ดํฐ๊ฐ ๋ฐ์ํ ์ ์ด๋ฅผ ํ์ฉํ ์ปค๋ ๋ฐ๋ ์ถ์ ๋ฒ์ ์ฌ์ฉํ์ฌ ์ด์๊ฐ์ ํต๊ณ์น๋ฅผ ๊ณ์ฐํ๊ฒ ๋๋ค. ์ด๋ ํ์ ์ง๋จ์จ์ 5%๋ก ๊ฐ์ ํ์ฌ ๊ฐ๊ฐ์ ์์ง๋จ์ ๋ํ ๊ณต์ ๊ฐ์ง ๊ธฐ์ค์ ์ ์ค์ ํ์๊ณ , ์ด์๊ฐ์ ํต๊ณ์น๊ฐ ๊ณต์ ๊ฐ์ ๊ธฐ์ค์ ๋ณด๋ค ๋ฎ๊ฒ ๋ ๊ฒฝ์ฐ ์ด์์ด ๊ฐ์ง๋๋ค.
์ธ ๋ฒ์งธ๋ก, ์ด์ ๋ฐ์ ์ ์์ธ์ด ๋๋ ๋ณ์์ ๊ฒฉ๋ฆฌ ๋ฐ ์ด์ ์ ํ ๊ฒฝ๋ก ๋ถ์์ ํจ๊ณผ์ ์ผ๋ก ์ํํ ์ ์๋ ๋ฐฉ๋ฒ๋ก ์ ์ ์ํ์๋ค. ์ ์๋ ๋ฐฉ๋ฒ๋ก ์์๋ ๋ง๋ฅด์ฝํ ๋๋ค ํ๋์ ํ๋ฅ ์ถ๋ก ๊ณผ์ ์ ํ์ฉํ์ฌ ์ด์ ๋ฐ์ ์ ๊ฐ ๋ณ์์ ์กฐ๊ฑด๋ถ ํ๊ณ ํ๋ฅ ์ ๊ณ์ฐํ๊ณ , ์ด๋ฅผ ํ์ฉํด ์๋กญ๊ฒ ์ ์๋ ์กฐ๊ฑด๋ถ ๊ธฐ์ฌ๋ ๊ฐ์ ๊ณ์ฐํ์ฌ, ์ด์์ ๋ํ ๊ฐ ๋ณ์์ ๊ธฐ์ฌ๋๋ฅผ ํ์
ํ ์ ์๋๋ก ํ๋ค. ์ด ๊ณผ์ ์์๋ ์ปค๋ ์ ๋ขฐ๋ ์ ํ ๋ฐฉ๋ฒ๋ก ์ด ์ฌ์ฉ๋๋๋ฐ, ์ด๋ ์ฐ์ ๋ณ์๋ฅผ ๊ฐ์ง๋ ๋ง๋ฅด์ฝํ ๋๋ค ํ๋์ ๋ํ์ฌ ํ๋ฅ ์ถ๋ก ์ ์ํํ ์ ์๋๋ก ํ๋ ๋ฐฉ๋ฒ๋ก ์ด๋ค. ์ปค๋ ์ ๋ขฐ๋ ์ ํ๋ฒ์ ์ฌ์ฉํ๋ฉด ์ ์ ์ํ์ ๊ณต์ ๋ฐ์ดํฐ๋ฅผ ํ์ฉํ์ฌ ๋ง๋ฅด์ฝํ ๋๋ค ํ๋๋ฅผ ๊ตฌ์ฑํ๋ ํ๋ผ๋ฏธํฐ ๊ฐ๋ค์ ํ์ตํ๊ณ , ์ด์ ๋ฐ์์ ์ด์ ๋ฐ์ดํฐ์ ๋ํ์ฌ ๊ฐ ๋ณ์์ ์กฐ๊ฑด๋ถ ๊ธฐ์ฌ๋ ๊ฐ์ ๊ณ์ฐํ ์ ์๊ฒ ๋๋ค. ์ด ๋ ๊ณ์ฐ๋ ์กฐ๊ฑด๋ถ ๊ธฐ์ฌ๋ ๊ฐ์ ํฌ๊ธฐ์, ์ด์ ๋ฐ์ ์ดํ ๊ฐ ๋ณ์์ ์กฐ๊ฑด๋ถ ๊ธฐ์ฌ๋ ๊ฐ์ ๋ณํ ๋ฐ์ ์๋๋ฅผ ์ข
ํฉ์ ์ผ๋ก ํ๋จํ์ฌ, ์ด์์ ์์ธ ๋ณ์์ ๋ํ ๊ฒฉ๋ฆฌ์ ์ด์ ์ ํ ๊ฒฝ๋ก ๋ถ์์ ํจ๊ณผ์ ์ผ๋ก ์ํํ ์ ์๊ฒ ๋๋ค.
๋ณธ ์ฐ๊ตฌ์์๋ ์ ์๋ ์ด์ ๊ฐ์ง ๋ฐ ์ง๋จ ๋ฐฉ๋ฒ๋ก ์ ์ฑ๋ฅ์ ๊ฒ์ฆํ๊ธฐ ์ํ์ฌ ํ
๋ค์ ์ด์คํธ๋ง ๊ณต์ ๋ชจ๋ธ์ ์ด๋ฅผ ์ ์ฉํ๊ณ ๊ฒฐ๊ณผ๋ฅผ ๋ถ์ํ์๋ค. ํ
๋ค์ ์ด์คํธ๋ง ๊ณต์ ์ ์๋
๊ฐ ๊ณต์ ๊ฐ์ ๋ฐฉ๋ฒ๋ก ์ ๊ฒ์ฆํ๊ธฐ ์ํ ๋ฒค์น๋งํฌ ๊ณต์ ์ผ๋ก ๋๋ฆฌ ์ฌ์ฉ๋์ด ์๊ธฐ ๋๋ฌธ์, ์ ์๋ ๋ฐฉ๋ฒ๋ก ์ ์ด์ ์ ์ฉํด ๋ด์ผ๋ก์จ ๋ค๋ฅธ ๊ณต์ ๊ฐ์ ๋ฐฉ๋ฒ๋ก ๋ค๊ณผ์ ์ฑ๋ฅ์ ๋น๊ตํด ๋ณผ ์ ์์๋ค. ๋ํ ๋ค์์ ๋จ์ ๊ณต์ ์ ํฌํจํ๊ณ ์๊ณ , ์ํ์ ์ธ ๋ณ์ ๊ด๊ณ ์ญ์ ํฌํจํ๊ณ ์๊ธฐ ๋๋ฌธ์ ์ ์๋ ๋ฐฉ๋ฒ๋ก ์ ์ฑ๋ฅ์ ์ํํด ๋ณด๊ธฐ์ ์ ํฉํ๋ค. ํ
๋ค์ ์ด์คํธ๋ง ๊ณต์ ๋ด๋ถ์๋ 28๊ฐ ์ข
๋ฅ์ ์ด์์ด ํ๋ก๊ทธ๋จ ์์ ๋ด์ฅ๋์ด ์๋๋ฐ, ์ ์๋ ๊ณต์ ๊ฐ์ง ๋ฐฉ๋ฒ๋ก ์ ์ ์ฉํ ๊ฒฐ๊ณผ ๋ชจ๋ ์ด์์ ๋ํ์ฌ 96% ์ด์์ ๋์ ์ด์ ๊ฐ์ง์จ์ ๋ํ๋ด์๋ค. ์ด๋ ๊ธฐ์กด์ ์ ์๋ ๊ณต์ ๊ฐ์ ๋ฐฉ๋ฒ๋ก ๋ค์ ๋นํ์ฌ ์๋ฑํ ๋์ ์์น์๋ค. ๋ํ ์ด์ ์ง๋จ ์ฑ๋ฅ์ ๋ถ์ํด ๋ณธ ๊ฒฐ๊ณผ, ๋ชจ๋ ์ด์์ ๋ํ์ฌ ์์ธ์ด ๋๋ ๋
ธ๋๋ฅผ ํจ๊ณผ์ ์ผ๋ก ํ์
ํ ์ ์์๊ณ , ์ด์ ์ ํ ๊ฒฝ๋ก ์ญ์ ์ ํํ๊ฒ ํ์งํ์ฌ ๊ธฐ์กด ๋ฐฉ๋ฒ๋ก ๋ค๊ณผ๋ ์ฐจ๋ณํ๋ ์ฑ๋ฅ์ ๋ํ๋ด์๋ค. ์ ์๋ ๋ฐฉ๋ฒ๋ก ์ ํ
๋ค์ ์ด์คํธ๋ง ๊ณต์ ์ ์ ์ฉํด ๋ด์ผ๋ก์จ, ๋ณธ ์ฐ๊ตฌ ๋ด์ฉ์ด ๊ณต์ ์ด์์ ๊ฐ์ง ๋ฐ ์ง๋จ์ ๋ํ ํตํฉ์ ์ธ ๋ฐฉ๋ฒ๋ก ์ค์์ ๊ฐ์ฅ ์ฐ์ํ ์ฑ๋ฅ์ ๋ํ๋ด๋ ๊ฒ์ ํ์ธํ ์ ์์๋ค.Contents
Abstract i
Contents iv
List of Tables vii
List of Figures ix
1 Introduction 1
1.1 Research Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Research Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3 Outline of the Thesis . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2 Markov Random Fields Modelling, Graphical Lasso, and Optimal Structure Learning 10
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2 Markov Random Fields . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3 Graphical Lasso . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.4 MRF Modelling & Structure Learning . . . . . . . . . . . . . . . . . 19
2.4.1 MRF modelling in process systems . . . . . . . . . . . . . . 19
2.4.2 Structure learning using iterative graphical lasso . . . . . . . 20
2.5 Application of Iterative Graphical Lasso on the TEP . . . . . . . . . . 24
3 Efficient Process Monitoring via the Integrated Use of Markov Random
Fields Learning and the Graphical Lasso 31
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.2 MRF Monitoring Integrated with Graphical Lasso . . . . . . . . . . . 35
3.2.1 Step 1: Iterative graphical lasso . . . . . . . . . . . . . . . . 36
3.2.2 Step 2: MRF monitoring . . . . . . . . . . . . . . . . . . . . 36
3.3 Implementation of Glasso-MRF monitoring to the Tennessee Eastman
process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
3.3.1 Tennessee Eastman process . . . . . . . . . . . . . . . . . . 41
3.3.2 Glasso-MRF monitoring on TEP . . . . . . . . . . . . . . . . 48
3.3.3 Fault detection accuracy comparison with other monitoring
techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
3.3.4 Fault detection speed & fault propagation . . . . . . . . . . . 95
4 Process Fault Diagnosis via Markov Random Fields Learning and Inference 101
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
4.2 Preliminaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
4.2.1 Probabilistic graphical models & Markov random fields . . . 106
4.2.2 Kernel belief propagation . . . . . . . . . . . . . . . . . . . . 107
4.3 Fault Diagnosis via MRF Modeling . . . . . . . . . . . . . . . . . . 113
4.3.1 MRF structure learning via graphical lasso . . . . . . . . . . 116
4.3.2 Kernel belief propagation - bandwidth selection . . . . . . . . 116
4.3.3 Conditional contribution evaluation . . . . . . . . . . . . . . 117
4.4 Application Results & Discussion . . . . . . . . . . . . . . . . . . . 118
4.4.1 Two tank process . . . . . . . . . . . . . . . . . . . . . . . . 119
4.4.2 Tennessee Eastman process . . . . . . . . . . . . . . . . . . 137
5 Concluding Remarks 152
Bibliography 157
Nomenclature 169
Abstract (In Korean) 170Docto
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