Cardiovascular Prevention and Pharmacotherapy

Special Articles

Perceptron: Basic Principles of Deep Neural Networks: Eung-Hee Kim, Hun-Sung Kim; Cardiovasc Prev Pharmacother. 2021;3(3):64-72. Published online July 31, 2021; DOI: https://doi.org/10.36011/cpp.2021.3.e9

Abstract PDF: Big data, artificial intelligence, machine learning, and deep learning have received considerable attention in the medical field. Attempts to use such machine learning in areas where medical decisions are difficult or necessary are continuously being made. To date, there have been many attempts to solve problems associated with the use of machine learning by using deep learning; hence, physicians should also have basic knowledge in this regard. Deep neural networks are one of the most actively studied methods in the field of machine learning. The perceptron is one of these artificial neural network models, and it can be considered as the starting point of artificial neural network models. Perceptrons receive various inputs and produce one output. In a perceptron, various weights (ω) are given to various inputs, and as ω becomes larger, it becomes an important factor. In other words, a perceptron is an algorithm with both input and output. When an input is provided, the output is produced according to a set rule. In this paper, the decision rules of the perceptron and its basic principles are examined. The intent is to provide a wide range of physicians with an understanding of the latest machine-learning methodologies based on deep neural networks.

From Traditional Statistical Methods to Machine and Deep Learning for Prediction Models: Jun Hyeok Lee, Dae Ryong Kang; Cardiovasc Prev Pharmacother. 2020;2(2):50-55. Published online April 30, 2020; DOI: https://doi.org/10.36011/cpp.2020.2.e6

Abstract PDF: Traditional statistical methods have low accuracy and predictability in the analysis of large amounts of data. In this method, non-linear models cannot be developed. Moreover, methods used to analyze data for a single time point exhibit lower performance than those used to analyze data for multiple time points, and the difference in performance increases as the amount of data increases. Using deep learning, it is possible to build a model that reflects all information on repeated measures. A recurrent neural network can be built to develop a predictive model using repeated measures. However, there are long-term dependencies and vanishing gradient problems. Meanwhile, long short-term memory method can be applied to solve problems with long-term dependency and vanishing gradient by assigning a fixed weight inside the cell state. Unlike traditional statistical methods, deep learning methods allow researchers to build non-linear models with high accuracy and predictability, using information from multiple time points. However, deep learning models cannot be interpreted; although, recently, many methods have been developed to do so by weighting time points and variables using attention algorithms, such as ReversE Time AttentIoN (RETAIN). In the future, deep learning methods, as well as traditional statistical methods, will become essential methods for big data analysis.

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