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Artificial neural network

lastmod 2026-10-11created 2014-10-3116 edits

An artificial neural network is an interconnected group of nodes, similar to the vast network of neurons in a brain. In the figure above, each circular node represents an artificial neuron, and an arrow represents a connection from the output of one neuron to the input of another.

An artificial neural network (neural network) is a mathematical model that aims to express some characteristics of brain function through computer simulation.

An artificial neural network refers broadly to any model in which artificial neurons (nodes), which form a network through synaptic connections, change the strength of those synaptic connections through training and thereby gain the ability to solve problems. In a narrow sense it is sometimes used to mean a multilayer perceptron trained with error backpropagation, but this is an incorrect usage; artificial neural networks are not limited to this.

Artificial neural networks include supervised learning, in which the network is optimized for a problem through the input of a teacher signal (correct answer), and unsupervised learning, which does not need a teacher signal. Supervised learning is used when there is a clear answer, and unsupervised learning is used for data clustering. As a result, in order to reduce dimensions, many of them can obtain good answers with relatively little computation for problems that are not linearly separable, on multidimensional data such as images or statistics. For that reason, they are applied in various fields such as pattern recognition and data mining.

Artificial neural networks can be built using specialized computers, but most are implemented by application software on ordinary computers.

Background

Research into the human central nervous system inspired the concept of neural networks. In artificial neural networks, artificial neurons are connected to each other to form a network that mimics biological neural networks.

There is no single formal definition of what an artificial neural network is. However, a set of statistical models is called neural (Neural) if it has the following characteristics.

  • It consists of a set of adjustable weights, that is, numerical parameters that can be adjusted by a learning algorithm.
  • It can infer non-linear functions of its inputs.

The adjustable weights represent the connection strengths between neurons, and they are activated during training or prediction.

Neural networks resemble biological neural networks in that functions are performed in parallel or collectively by the units, rather than as subtasks assigned to the various units. The word 'neural network' usually refers to models used in statistics, cognitive psychology, and artificial intelligence. Neural network models that emulate the central nervous system are part of theoretical neuroscience and computational neuroscience.

About this

An artificial neural network uses a Combination function, which combines the input variables, and an Activation function, which combines and transforms the input information. The Combination function turns the pieces of input information into a single piece of information, most commonly using a weighted average, and the Activation function is a function that passes the combined value of the input information to the output layer or hidden layer, converting the combined value of the input information into a value within a certain range.

Category

  • Perceptron
    • Adaline (Adaptive Linear Neuron)
    • Madaline (Many Adaline)
  • Multilayer Perceptron
    • Has an input layer, an output layer, and one or more hidden layers (Hidden layer).
    • The training method is as follows.
      1. Present the input data to each unit of the input layer.
      2. This signal is transformed at each unit and passed to the intermediate layer.
      3. Finally, the result comes out at the output layer.
      4. Compare the output value with the desired output value and adjust the connection strengths in the direction that reduces the difference.
    • Backpropagation
  • Hopfield Network
    • Associative Memory
  • Kohonen Network
    • Competitive Learning
      • Each neuron calculates how close its connection-strength vector is to the input vector. The neurons then compete with each other to be granted the privilege of learning, and the neuron with the shortest distance wins.
    • Self-organizing Feature Maps
  • ART Network (Adaptive Resonance Theory Network)
  • Simulated Annealing
  • Boltzmann Machine
  • Counterpropagation network
    • A combination of Kohonen's self-organizing map and Grossberg's outstar algorithm.
  • Cognitron
    • A pattern recognition multilayer neural network model based on the way the human visual system recognizes things
    • A pattern recognition model developed by Fukushima (K, Fukushima) in 1975; a multilayer neural network model that performs competitive learning.
  • Neocognitron
  • Fuzzy neural network model
    • SONN (Self-Organizing Neural Network)
      • When the connection strengths between neurons are adjusted, each connection strength is adjusted according to its fuzzy similarity with the input vector.

Table of Machine learning

Table of Machine learning

Learning Course

Theory

Probability theory → Bayesian probability

Machine learning

Hypothesis → Loss function → Gradient descent → Overfitting

Neural network

Artificial neuron → Perceptron → Multilayer perceptron → (Example) → Feedforward neural network → Activation function (Sigmoid function & Euler's number) → Softmax function (Loss function) → Backpropagation (Gradient descent) → (Example)

Deep learning

Convolutional neural network (CNN) & Region-based Convolutional Network (RCNN, R-CNN)

ETC

Tutorials

Theory

Basic

Terms

Probability theory

Bayesian probability, Decision Theory, Probability Density Function (PDF), Radial basis function (RBF), Hyperparameter

Neuroscienced

Neuron

Statistics

Covariance, Statistical classification, Confusion matrix, Cross-validation, Root-mean-square deviation (MESD), Mean squared error

Graph theory

Matrix

General matrix-matrix multiplication (gemm), Toeplitz matrix, im2col

Other

Computational learning theory, Empirical risk minimization, Occam learning, PAC learning, Statistical learning, VC theory, Bayesian network, Markov random field, Hidden Markov Model (HMM), Conditional Random Field, Normal Bayes Classifier, Energy Based Model, Occam's razor, Ground truth

Algorithm types

Supervised Learning

Support Vector Machine (SVM), Hidden Markov model, Regression analysis, Neural network, Naive Bayes classifier, K-Nearest Neighbor (K-NN), Decision trees, Ensembles (Bagging, Boosting, Random forest), Relevance vector machine (RVM)

Unsupervised learning

Clustering, Independent component analysis

Semi-supervised learning

Generative models, Low-density separation, Graph-based methods, Heuristic approaches

Other learning

Reinforcement learning, deep learning

By topic

Structured prediction

Graphical models (Bayes net, CRF, HMM)

Parameter estimation algorithms

Dynamic programming, EM algorithm

Approximate inference techniques

Monte Carlo method, AdaBoost

Approaches

Decision tree learning, association rule learning, genetic programming, inductive logic programming, clustering, Bayesian networks, reinforcement learning, representation learning, similarity metric learning

Modeling

Neural network, SVM K-NN, decision trees, Genetic Algorithm, genetic programming, Gaussian process regression, linear discriminant analysis, perceptron, radial basis function network

Recommender system (Korean: 추천 시스템)

Collaborative filtering (Korean: 협업 필터링), Content-based filtering (Korean: 컨텐츠 기반 필터링), Hybrid recommender systems

Data mining

Cross-validation (k-fold), Data set (Training set, Validation set, Test set)

Regression analysis

Linear regression, Logistic Regression, Logit function, Multinomial logistic regression (Softmax Regression)

Clustering

k-means clustering, BIRCH, Hierarchical, Expectation-maximization (EM), DBSCAN, OPTICS, Mean-shift

By type

3D Machine Learning

Artificial Neural Networks; ANN

Artificial neuron

Perceptron, Sigmoid neuron

Combination function & Activation function

Sigmoid function, Rectified linear units (ReLU), 1x1 Convolution

Loss function or Cost function

Softmax, Sum of squares (Euclidean), Hinge / Margin, Cross entropy, Infogain, Accuracy and Top-k

Algorithms

Multilayer perceptron (MLP), Feed-forward Neural Network (FNN), Long short-term memory (LSTM), Autoencoder, Self-organizing map (SOM), Network In Network (NIN), Adaptive neuro fuzzy inference system (ANFIS)

Deep learning

Deep neural network (DNN), Convolutional neural network (CNN) & Regions with Convolutional Neural Network (RCNN, R-CNN, SSD), Recurrent neural network (RNN), Gated Recurrent Unit (GRU), Restricted Boltzmann Machine (RBM), Deep Belief Network (DBN), Deep Q-Networks, Deep hyper network (DHN), Deconvolutional Network, Fully Convolutional Networks for Semantic Segmentation (FCN), Generative Adversarial Networks (GAN), Learning Deconvolution Network for Semantic Segmentation, Multi-Scale Context Aggregation by Dilated Convolutions (Dilated Convolutions), Dynamic Routing Between Capsules (Capsules Network), YOLO, Path Aggregation Network for Instance Segmentation (PANet), Image-to-Image Translation with Conditional Adversarial Networks (pix2pix), CycleGAN, BicycleGAN, SlowFast, Kinetics, AVA, MelGAN, EfficientDet, SinGAN, Panoptic Segmentation, U-Net, MONAI, CenterNet, DeepLab, HRNet, OCRNet, ResNeSt

Models

GoogLeNet, LeNet, AlexNet, ReNet, RCNN, SPPnet, Fast R-CNN, Faster R-CNN, VGG, SqueezeNet, PointNet, Mask R-CNN, MaskLab, OSMN (Video Segmentation), ColorNet, EfficientNet

Problems

Dimensionality reduction

Curse of dimensionality, Factor analysis, CCA, independent component analysis (ICA), LDA, non-negative matrix factorization (NMF), principal component analysis (PCA), t-SNE

Underfitting & Overfitting

Early stopping, Model selection, Normalization, Regularization (L1, L2, Dropout), Generalization

Initialization

Xavier Initialization

ETC

Bias-variance dilemma, Vanishing gradient problem, Local minimum problem, Batch Normalization, Standardization, AutoML

Optimization

Hyperparameter, Simulated annealing, Early stopping, Feature scaling, Normal Equation, Gradient descent, Stochastic gradient descent (SGD), Backpropagation, Convex optimization, Performance Tuning, im2col, Dense-Sparse-Dense Training for Deep Neural Networks (DSD), Deep Compression, Pruning Neural Networks, Shake-Shake regularization, Accurate Large Minibatch SGD

ETC

Libraries

OpenCV, Deeplearning4j (DL4J), Torch, PyTorch, Theano, Caffe, TensorFlow, MMDetection, ConvNetJS, cuDNN, Netscope, Microsoft Azure Machine Learning Studio, OpenPose, DensePose, Keras, tiny-dnn, Detectron, Stanford CoreNLP, Aifiddle, Kubeflow, OpenNMT, alibi-detect, Flashlight (facebook), MediaPipe, Weights and Biases

Dataset

MNIST (handwriting data), ImageNet, CIFAR-10, TinyImages, PASCAL VOC, COCO, AVSS, YouTube-VOS

Annotation tools

labelme, cvat, f-BRS, COCO Annotator

See also

Artificial intelligence, autonomous robots, bioinformatics, computational intelligence, computer vision, data mining, pattern recognition, big data

Unknown keyward

Classification, Anomaly detection, Association rules, Reinforcement learning, Structured prediction, Feature engineering, Feature learning, Online learning, Semi-supervised learning, Unsupervised learning, Learning to rank, Grammar induction, Local outlier factor, Minimum Description Length (MDL), Bayesian MAP, Structural Risk Minimization (SRM), Long Narrow Valley, Word2vec, Autoregressive integrated moving average (ARIMA)

Documentation

Bayesian probability

Bayesian Reasoning and Machine Learning
http://web4.cs.ucl.ac.uk/staff/D.Barber/pmwiki/pmwiki.php?n=Brml.Online
http://web4.cs.ucl.ac.uk/staff/D.Barber/textbook/020217.pdf
020217_-_Bayesian_Reasoning_and_Machine_Learning.pdf

Deep learning

ImageNet Classification with Deep Convolutional Neural Networks (AlexNet)
http://www.cs.toronto.edu/~fritz/absps/imagenet.pdf
http://papers.nips.cc/paper/4824-imagenet-classification-with-deep-convolutional-neural-networks.pdf
ImageNet_Classification_with_Deep_Convolutional_Neural_Networks.pdf
[Korean translation] ImageNet classification using deep convolutional neural networks
ImageNet_Classification_with_Deep_Convolutional_Neural_Networks_-_ko.pdf
Going deeper with convolutions (GoogleNet)
http://arxiv.org/pdf/1409.4842v1.pdf
Going_deeper_with_convolutions.pdf
Translation: GoogleNet
Special feature article: Deep Hypernetwork models (Seoul National University/Byoung-Tak Zhang)
Deep_Hypernetwork_models_201508.pdf
[Mocrosoft] Deep Residual Learning for Image Recognition (Winner ILSVRC2015)
Deep_Residual_Learning_for_Image_Recognition(Winner_ILSVRC2015)_Microsoft.pdf
[Microsoft] Fast R-CNN, Towards Real-Time Object Detection with Region Proposal Networks (Winner ILSVR2015)
Fast_R-CNN,Towards_Real-Time_Object_Detection_with_Region_Proposal_Networks(Winner_ILSVR2015)_Microsoft.pdf
Learning Deconvolution Network for Semantic Segmentation
http://cvlab.postech.ac.kr/research/deconvnet/
Deep EXpectation of apparent age from a single image
https://data.vision.ee.ethz.ch/cvl/rrothe/imdb-wiki/
Inside-Outside Net: Detecting Objects in Context with Skip Pooling and Recurrent Neural Networks.
Inside_outside_net_detecting_objects_in_context_with_skip_pooling_and_recurrent_neural_networks_2015.pdf
A paper on Small Object detection methods.
Cho Dae-hyup's blog - Understanding deep learning and TensorFlow for those who gave up on math
http://bcho.tistory.com/1208
Machine_learning_ebooks_-_Machine_learning_for_those_who_abandon_math.pdf
Densely Connected Convolutional Networks (DenseNets)
Deep learning CVPR2017 Best Paper Award
Deep Learning Interviews book: Hundreds of fully solved job interview questions from a wide range of key topics in AI.
Deep learning interview book
A collection of practical questions and solutions for master's/PhD students and job seekers learning machine learning
A printed copy can also be purchased, but the full PDF is freely available
[Recommended] "Key AI Glossary You Must Know in the AI Era, Examined Through 2025 AI Trends and Issues" published by NIA (National Information Society Agency)
Key glossary you must know in the AI era (168p PDF) | GeekNews
https://www.nia.or.kr/site/nia_kor/ex/bbs/View.do?cbIdx=82618&bcIdx=28928&parentSeq=28928
Nia.or.kr_-ai-_2025_terms.pdf
There Will Be a Scientific Theory of Deep Learning
There will be a scientific theory of deep learning. | GeekNews
There Will Be a Scientific Theory of Deep Learning
A paper arguing that a scientific theory characterizing key properties of deep learning, such as the training process, hidden representations, final weights, and performance, is taking shape
Presents five research threads (interpretable idealized settings, tractable limits, simple mathematical laws, hyperparameter theory, universal behaviors) as its core evidence

Tutorials

Getting Started with Deep Learning Properly (author Takayuki Okatani / translator Shim Hyo-seop)
Deep_Learning_-Takayuki_Okatani-2015-_sample.pdf
Introductory Guide to Machine Learning - IDG Deep Dive
http://www.itworld.co.kr/techlibrary/97428
IDG_DeepDive_Machine_learning-20160113.pdf
Understanding Deep Learning (unpublished; 2016-08-22 ver)
Understanding_deep_learning_0822.pdf
Fundamental of Reinforcement Learning
https://www.gitbook.com/book/dnddnjs/rl/details
Fundamental_of_Reinforcement_Learning.pdf
MODULABS - Fundamentals of reinforcement learning
Deep Learning Papers Reading Roadmap (deep learning paper roadmap)
https://github.com/songrotek/Deep-Learning-Papers-Reading-Roadmap/blob/master/README.md
Deep_Learning_Papers_Reading_Roadmap.md.zip
[Recommended] Machine Learning-based Web Exception Detection (reference site related to the Financial Security Institute project!)
https://cloudfocus.aliyun.com/Machine-Learning-based-Web-Exception-Detection-89782?spm=a2c1b.a2c1b4.a2c1b4.16.ZSQoEd
Machine_Learning-based_Web_Exception_Detection_-Insights_and_Trends-_Alibaba_Cloud_Focus.pdf
Machine learning basics parts 1–57 (Odds-and-ends exploration - Chamstudy ePaiai : Naver Blog)
http://sams.epaiai.com/220498694383
Microsoft releases ML for Beginners course
A 12-week, 24-lesson curriculum made by the MS Azure Clouds Advocates team
A classic machine learning course using Scikit-learn (deep learning will come as a separate AI course)
https://github.com/microsoft/ML-For-Beginners
CS146S: The Modern Software Developer (Korean) | GeekNews
[Original] CS146S Korean Edition | The Modern Software Developer
The official Korean version of Stanford's CS146S course

Compress model

Deep Compression and EIE - Deep Neural Network Model Compression and Efficient Inference Engine
Deep_compression_and_EIE_PPT.pdf
Learning bothWeights and Connections for Efficient Neural Networks
Learning_both_weights_and_connections_for_efficient_neural_networks_2015.pdf

Convolutional neural network

A CNN Presentation using Reveal.js.
Author - me
Reveal-ml.tar.gz
Gradient-Based Learning Applied to Document Recognition
http://yann.lecun.com/exdb/publis/pdf/lecun-01a.pdf
Gradient-Based_Learning_Applied_to_Document_Recognition.pdf
Visualizing and Understanding Convolutional Neural Networks
http://arxiv.org/abs/1311.2901
1311.2901v3.pdf
Compressing CNN for Mobile Device (Samsung) - the need for CNN model compression etc ...
[http://mlcenter.postech.ac.kr/files/attach/workshop_fall_2015/삼성전자_김용덕_박사.pdf](http://mlcenter.postech.ac.kr/files/attach/workshop_fall_2015/삼성전자_김용덕_박사.pdf)
Samsung_-_Compressing_CNN_for_Mobile_Device.pdf
Using Filter Banks in Convolutional Neural Networks for Texture Classification
https://arxiv.org/abs/1601.02919

Deep belief network

The Applications of Deep Learning on Traffic Identification
Us-15-Wang-The-Applications-Of-Deep-Learning-On-Traffic-Identification-wp.pdf
https://www.blackhat.com/docs/us-15/materials/us-15-Wang-The-Applications-Of-Deep-Learning-On-Traffic-Identification-wp.pdf

Deconvolution neural network

Learning Deconvolution Network for Semantic Segmentation
http://cvlab.postech.ac.kr/research/deconvnet/
https://arxiv.org/abs/1505.04366
1505.04366.pdf

Segmentation

Learning to Segment (Facebook Research)
https://research.fb.com/learning-to-segment/
DeepMask+SharpMask as well as MultiPathNet.
Recurrent Instance Segmentation
https://arxiv.org/abs/1511.08250
1511.08250.pdf
Slideshare - Single Shot MultiBox Detector and Recurrent Instance Segmentation
vid2vid
https://github.com/NVIDIA/vid2vid
Pytorch implementation for high-resolution (e.g., 2048x1024) photorealistic video-to-video translation.
It can be used for turning semantic label maps into photo-realistic videos, synthesizing people talking from edge maps, or generating human motions from poses.

Fire Detection

Organized under Fire Detection#Deep learning based.

Background subtraction

Organized under Background subtraction#Deep learning based.

LSTM

Organized under Long short-term memory.

Learning

Siamese Neural Networks for One-Shot Image Recognition
https://jayhey.github.io/deep%20learning/2018/02/06/saimese_network/
Training a network in deep learning requires a very large amount of training data. One-shot learning overcomes this drawback by training the network so that it can classify even with only one image per label.

NVIDIA AI Developer Newsletter

[Recommended] AI Can Transform Anyone Into a Professional Dancer
https://news.developer.nvidia.com/ai-can-transform-anyone-into-a-professional-dancer/
https://arxiv.org/abs/1808.07371
Transforming Standard Video Into Slow Motion with AI
https://news.developer.nvidia.com/transforming-standard-video-into-slow-motion-with-ai/
NVIDIA SPLATNet Research Paper Wins a Major CVPR 2018 Award
https://news.developer.nvidia.com/nvidia-splatnet-research-paper-wins-a-major-cvpr-2018-award/
AI Learns to Play Dota 2 with Human Precision
https://news.developer.nvidia.com/ai-learns-to-play-dota-2-with-human-precision/
[Recommended] This AI Can Automatically Remove the Background from a Photo
https://news.developer.nvidia.com/this-ai-can-automatically-remove-the-background-from-a-photo/
NVDLA Deep Learning Inference Compiler is Now Open Source
https://devblogs.nvidia.com/nvdla/

Nature

Deep learning of aftershock patterns following large earthquakes
https://www.reddit.com/r/MachineLearning/comments/9bo9i9/r_deep_learning_of_aftershock_patterns_following/
https://www.nature.com/articles/s41586-018-0438-y
https://drive.google.com/file/d/1DSqLgFZLuNJXNi2dyyP_ToIGHj94raWX/view

Cancer

Deep Neural Networks Improve Radiologists’ Performance in Breast Cancer Screening
https://medium.com/@jasonphang/deep-neural-networks-improve-radiologists-performance-in-breast-cancer-screening-565eb2bd3c9f

Text Generation

See Text Generation.

VizSeq - A Visual Analysis Toolkit for Text Generation Tasks
https://arxiv.org/abs/1909.05424

Favorite site

Machine learning

E-book

Data analysis

Artificial neural network

Convolutional neural network

Segmentation

Deep learning

Deep learning libraries

Andrew Ng

Machine Learning Exercises In Python

Guides

Tutorials

Data pool

Service

Sample images good for use in proposals

Online demo

References


  1. Sigmoid_Function_of_Artificial_Neural_Network.pdf ↩

  2. Machine_Learning_-_OpenCV_ML_algorithms.pdf ↩

  3. S1_nn.pdf ↩

  4. Sigmoid_Function_of_Artificial_Neural_Network.pdf ↩

  5. Aistudy.co.kr_-_theory_oh.pdf ↩

  6. VGG_Convolutional_Neural_Networks_Practical.pdf ↩

  7. ConvNets_24_April.pdf ↩

  8. Forward_and_Backward_Propagation_of_the_Convolutional_Layer.pdf ↩

  9. The_easiest_way_to_understand_CNN_backpropagation.pdf ↩

  10. A_Look_at_Image_Segmentation_using_CNNs_–_Mohit_Jain.pdf ↩

  11. Artificial_Intelligence_6-Deep_Learning.pdf ↩

  12. The_Devil_is_always_in_the_Details_-_Must_Know_Tips_and_Tricks_in_DNNs.pdf ↩

  13. Openresearch.ai-190921.zip ↩

  14. Stanford-machine_learning-andrew_ng-lectures.tar.gz ↩

  15. OLD URL: https://class.coursera.org/ml-005/lecture ↩

  16. Sanghyuk's Github pages blog using octropress ↩

  17. SanghyukChun.github.io-006e2ae.tar.gz ↩

  18. 1ambda.github.io-19962c5.tar.gz ↩

  19. Machine_Learning_Exercises_In_Python_-_Part_1.pdf ↩

  20. Machine_Learning_Exercises_In_Python_-_Part_2.pdf ↩

  21. Machine_Learning_Exercises_In_Python_-_Part_3.pdf ↩

  22. Machine_Learning_Exercises_In_Python_-_Part_4.pdf ↩

  23. Machine_Learning_Exercises_In_Python_-_Part_5.pdf ↩

  24. Machine_Learning_Exercises_In_Python_-_Part_6.pdf ↩

  25. Machine_Learning_Exercises_In_Python_-_Part_7.pdf ↩

  26. Machine_Learning_Exercises_In_Python_-_Part_8.pdf ↩

  27. Samsung_software_membership_-_Neural_network_01.pdf ↩

  28. Samsung_software_membership_-_Neural_network_02.pdf ↩

  29. GPU_-how_much_faster_than_CPU-_NeoBrain.pdf ↩

  30. 1ambda.github.io-master-5c58cab.zip ↩

  31. Gitbook_-leonardoaraujosantos-_artificial-inteligence.pdf ↩

  32. 170915_Tensorflow_Seminar_From_Deep_Learning_Theory_to_Practice_-_POSTECH.pdf ↩

  33. Fueling_the_Gold_Rush_-The_Greatest_Public_Datasets_for_AI-Startup_Grind-_Medium.pdf ↩